The integration of dynamic, sparse structures like Mixture-of-Experts (MoE) with parameter-efficient adapters (e.g., LoRA) is a powerful technique for enhancing Large Language Models (LLMs). However, this architectural enhancement comes at a steep cost: despite minimal increases in computational load, the inference latency often skyrockets, leading to decoding speeds slowing by over 2.5 times. Through a fine-grained performance analysis, we pinpoint the primary bottleneck not in the computation itself, but in the severe overhead from fragmented, sequential CUDA kernel launches required for conventional dynamic routing. To address this challenge, we introduce AdaFuse, a framework built on a tight co-design between the algorithm and the underlying hardware system to enable efficient dynamic adapter execution. Departing from conventional layer-wise or block-wise routing, AdaFuse employs a token-level pre-gating strategy, which makes a single, global routing decision for all adapter layers before a token is processed. This ``decide-once, apply-everywhere'' approach effectively staticizes the execution path for each token, creating an opportunity for holistic optimization. We capitalize on this by developing a custom CUDA kernel that performs a fused switching operation, merging the parameters of all selected LoRA adapters into the backbone model in a single, efficient pass. Experimental results on popular open-source LLMs show that AdaFuse achieves accuracy on par with state-of-the-art dynamic adapters while drastically cutting decoding latency by a factor of over 2.4x, thereby bridging the gap between model capability and inference efficiency.

Large Language Models (LLMs) have shown strong capabilities in open-domain question answering (QA), but deploying them in real-world online systems introduces critical challenges. These include: (1) handling both simple and complex queries with appropriate levels of reasoning, (2) minimizing latency without compromising answer quality, and (3) maintaining answer consistency under evolving and noisy retrieval contexts. To address these challenges, we propose Retain-to-Refine (ℜ2ℜ), an adaptive agent-based QA framework designed for practical deployment. ℜ2ℜ integrates a Query Critic Agent (QCA) to assess query difficulty and route it accordingly: simple queries are answered directly using fast, prompt-based LLM calls, while complex queries are handled by a Memory Augmented Agent (MAA). MAA performs iterative reasoning guided by a unique long-short memory mechanism. Long-term memory retains and consolidates stable, core facts to ground the reasoning process, while short-term memory identifies transient information gaps to formulate highly focused subsequent queries. To ensure evidence quality, a Supervised Retrospection module validates and filters retrieved documents at each step. This agent-based design enables ℜ2ℜ to dynamically allocate computation based on question complexity, reducing unnecessary overhead while preserving high-quality answers when multi-step reasoning or external knowledge is required. Extensive evaluations across various settings and datasets demonstrate that the efficiency of R2R across diverse question types. In online settings, ℜ2ℜ delivers substantial gains in both response quality and efficiency, making it well-suited for large-scale industrial deployment in real-time QA services.

Result reproduction of computer networking research is challenging as the scarcity of open-source implementations and the complexity of heterogeneous system architectures. Even though Large Language Models have demonstrated potential in code generation, existing code generation frameworks often fail to address the long-context constraints and intricate logical dependencies, which are vital in reproducing network systems from academic papers. Thus, we introduce RepLLM, an end-to-end multi-agent framework designed to automate code reproduction from paper content. RepLLM features a collaborative architecture comprising four specialized agents—Content Parsing, Architecture Design, Code Generation, and Audit & Repair, which are coordinated through Shared Memory mechanism to ensure global context consistency. With the enhancement of Structured Chain-of-Thought LLM reasoning and a sandbox-isolated static-dynamic debugging methodology, our framework effectively resolves semantic discrepancies and runtime errors, thereby improving reliable reproductions. Extensive evaluations on representative papers in top conferences demonstrate that RepLLM outperforms state-of-the-art system-level LLM frameworks in generating compile-ready and logically correct systems. Our results show that, with the aid of RepLLM, we can reproduce 95% of the original benchmarks within approximately two hours while reducing token consumption by up to 10% compared with state-of-the-art baselines.

In today's cloud networks, host servers widely deploy Data Processing Units (DPUs) as network accelerators under the "Sep-Path" paradigm. However, as server capabilities scale with increasing CPU cores and network bandwidth, the software slow path (executed on a DPU's CPU) has become a critical bottleneck for workloads with high new-flow rates. Meanwhile, new-flow setup logic on host servers must continuously evolve to meet diverse and changing customer demands, making flexibility a key requirement alongside performance. To address this gap, we present XFir, the first hardware-accelerated new-flow setup system for cloud host servers that delivers high CPS throughput while preserving sufficient flexibility. XFir leverages a next-generation DPU equipped with a Cloud Network co-Processor (CNP) to execute the host server's new-flow setup logic. XFir redesigns the host-server flow-setup datapath and table layout, optimizes LPM lookups, and introduces CPU-CNP collaboration mechanisms to further improve performance and reliability. Our evaluation shows that XFir achieves over 776K new-flow CPS on a single host server with 11.7μs slow-path latency. Compared to prior work (Fornax), XFir achieves 4.8x CPS and reduces latency by 69.2%. Moreover, XFir is cost-effective to deploy, requiring only a single DPU per host. Overall, XFir improves new-flow throughput while maintaining development flexibility at low financial cost.

Low Earth Orbit (LEO) Synthetic Aperture Radar (SAR) satellites conventionally rely on dedicated communication links, which impose prohibitive hardware, spectrum, and power overhead as satellite constellations scale. This paper presents CommSAR, a novel system that reuses existing SAR imaging waveforms to enable bidirectional communication without modifying satellite hardware or compromising imaging performance. For the downlink, data are embedded by modulating the starting frequency offset of the imaging waveform, preserving the waveform structure and imaging quality. For the uplink, we propose a compact, low-cost programmable metasurface to replace conventional large, expensive antennas, significantly lowering the barrier for dense ground station deployment. To handle extreme satellite dynamics, we employ an opposite-slope waveform as a pilot to compensate for mobility-induced effects. We implement a ground station prototype of CommSAR and validate its performance using an in-orbit commercial SAR satellite and a UAV SAR platform. Experimental results show that CommSAR preserves imaging performance without degradation while achieving downlink and uplink data rates of up to 105 kbps and 112 kbps, respectively, significantly outperforming the state of the art and demonstrating utility-grade performance.

Many real-world systems can be modeled as graphs, where nodes store and consume entities, actively produce them, or have them emerge naturally, and edges transport them between nodes. This paper studies the networked control problem on such large-scale systems, aiming to decide production and transportation over time to maximize long-term profits, subject to node or edge capacity constraints. Existing SOTAs either fail to guarantee feasibility or cannot scale to large-scale systems. We propose a two-stage policy that integrates a constrained optimization layer after a neural network to explicitly enforce constraints and ensure feasibility. By leveraging the problem structure to obtain expert actions and designing a decision-focused and differentiable loss to enable imitation learning, our method significantly improves efficiency and scalability. In small-scale systems with action dimensions in the order of 10, our method achieves 60x sample efficiency over SOTAs on average. In large-scale systems with action dimensions ranging from 100 to 100000, where SOTAs fail to train, our method converges quickly and outperforms non-learning-based baselines significantly.

Remote Direct Memory Access (RDMA) offers high performance through OS kernel bypass and has become a key technology in modern data centers. By exploiting memorysemantic operations, RDMA-based data structures can achieve high scalability and significantly reduce CPU utilization compared with traditional Ethernet-based systems. However, classic sorted indexes such asSkiplistsuffer from low throughput under RDMA memory semantics due to frequent and costly remote accesses. To achieve both scalability and high throughput for a lock-based concurrent Skiplist, this paper introduces a hybrid paradigm that combines one-sided and two-sided RDMA operations. This proposal is built upon a re-evaluation of core design choices in RDMA, including transport modes, caching strategies, and memory management. Building on this paradigm, we designHybridSkipList+, a distributed Skiplist system that integrates a client-side coherent cache with pull-based synchronization to reduce expensive network round trips, and a semi-continuous memory allocator to enhance RDMA access locality. We implementHybridSkipList+ on an eight-machine RDMA cluster and conduct extensive evaluations. Results show that HybridSkipList+ outperforms two baseline systems by up to 4.41× and 3.45× under typical workload conditions.

Deploying large language models (LLMs) in mobile and edge computing environments is constrained by limited on-device resources, scarce wireless bandwidth, and frequent model evolution. Although edge-cloud collaborative inference with speculative decoding (SD) can reduce end-to-end latency by executing a lightweight draft model at the edge and verifying it with a cloud-side target model, existing frameworks fundamentally rely on tight coupling between the two models. Consequently, repeated model synchronization introduces excessive communication overhead, increasing end-to-end latency, and ultimately limiting the scalability of SD in edge environments. To address these limitations, we propose FlexSpec, a communication-efficient collaborative inference framework tailored for evolving edge-cloud systems. The core design of FlexSpec is a shared-backbone architecture that allows a single and static edge-side draft model to remain compatible with a large family of evolving cloud-side target models. By decoupling edge deployment from cloud-side model updates, FlexSpec eliminates the need for edge-side retraining or repeated model downloads, substantially reducing communication and maintenance costs. Furthermore, to accommodate time-varying wireless conditions and heterogeneous device constraints, we develop a channel-aware adaptive speculation mechanism that dynamically adjusts the speculative draft length based on real-time channel state information and device energy budgets. Extensive experiments demonstrate that FlexSpec achieves superior performance compared to conventional SD approaches in terms of inference efficiency.

Space Situational Awareness (SSA) relies on Low Earth Orbit (LEO) satellites to capture continuous, highresolution imagery critical for identifying space threats. The vast volume of SSA images overwhelms satellite network throughput, hindering timely transmission and processing. This paper presents a reinforcement learning (RL)-driven distributed sparse coding framework that integrates novel compression algorithms with orbital RL to address these challenges. First, we introduce an Aggregated Dictionary Learning (ADL) algorithm and a Context-aware Adaptive Binary Arithmetic Coding (CABAC) algorithm, achieving a 93.78% compression ratio by exploiting the high sparsity and spatiotemporal redundancy of SSA images. Second, the proposed compression workflow is deployed across LEO satellites in a distributed manner, where both overlapping and non-overlapping regions of images are dynamically partitioned and processed in parallel to optimize resource utilization and reduce latency. An Orbital Double Deep Q-Network (DQN) framework is proposed to optimize task offloading decisions by (1) integrating orbital dynamics into the state space, and (2) adaptively partitioning images based on visible LEO resources. Evaluations demonstrate that our framework achieves 100% task completion under visibility constraints and a 51.61% reduction on CPU and RAM occupation time compared to centralized processing.

Robotic swarm coordination holds transformative potential for applications such as warehouse automation, search & rescue, and entertainment. However, approaches relying on wearable devices or vision-based systems are often constrained by hardware-intensive, high computational requirements, reliance on line-of-sight, and privacy concerns. Wireless sensing, particularly using Channel State Information (CSI), offers a promising alternative by translating environmental perturbations into CSI variation data. Nevertheless, existing CSI-based systems face significant challenges in domain adaptation, resource limitation, and scalability issues. This paper introduces MaestroBot, a hierarchical motion coordination system that combines distributed CSI-based wireless sensing with domain-adaptive learning to address these limitations. For leader robots, the system features a lightweight hand gesture recognition model, built on a “Hybrid-Single” knowledge distillation framework, achieving up to 95.87% accuracy while maintaining adaptability across diverse domains. For follower robots, the hierarchical motion propagation model leverages localized CSI analysis and dual-layer error correction mechanisms to deliver 97.2% accuracy with a low latency of 0.085 seconds, even in multi-row formations. Additionally, its cost-effective hardware design ensures practical scalability and real-world deployability. These results position MaestroBot as an efficient, robust, and privacy-preserving solution for large-scale robotic swarm coordination in dynamic environments.

Neural Radiance Fields (NeRF) offers superior reconstruction accuracy over traditional methods like point clouds. This is particularly advantageous for applications in retail, VR, and navigation. However, when representing a complex scene with multiple semantically meaningful objects, especially those containing high-frequency details, the conventional single NeRF approach struggles to accurately capture these intricate details. Furthermore, the state-of-the-art multi-NeRF solutions, though effectively capturing details by representing each object as a separate NeRF, are too resource-intensive to be run on mobile devices. Existing NeRF rendering acceleration studies focus on single NeRF data representation and its framework improvements, without resorting to the visibility information for further optimization and considering the practical multi-NeRF rendering scenario. In this paper, we present Mosaic, a multi-NeRF cloud rendering system that facilitates high-fidelity, and low-latency cloud rendering for complex scenes. We first design a multi-resolution controller to dynamically determine the resolution for each pixel based on its contextual details and view direction. It then incorporates a visibility-aware region pruner to effectively eliminate unneeded pixels to avoid being rendered. The extensive experiments on various scenes show that Mosaic can achieve high-fidelity rendering with 43% lower transmission cost and up to 70% smaller computation consumption when compared with other state-of-the-art benchmarks.

Understanding the nature of user-device interactions (e.g., who is using the device and what he/she is doing with it) is critical for many applications including time management, user profiles, and privacy protection. However, in scenarios where mobile devices are shared among family members or multiple employees in a company, conventional account-based statistics are not meaningful. This poses an even bigger problem when dealing with sensitive data. Moreover, fingerprint readers and front-facing cameras were not designed to continuously identify users. In this study, we developedMagPrint++, a novel approach to fingerprint users based on unique patterns in the electromagnetic (EM) signals associated with the specific use patterns of users. Initial experiments showed that time-varying EM patterns are unique to individual users. They are also temporally and spatially consistent, which makes them suitable for fingerprinting.MagPrint++has a number of advantages over existing schemes: i) Non-intrusive fingerprinting, ii) implementation both on COTS mobile phones and a small and easy-to-deploy device, and iii) high accuracy thanks to the proposed classification algorithm. In experiments involving 30 users,MagPrint++achieves$94.3\%$accuracy in classifying users from these traces, which represents a$10.9\%$improvement over the state-of-the-art classification method.

This paper proposes the concept of a “loss-tolerant” RDMA network, instantiating as NüWa. It reveals the fundamental issues under a lossy fabric — packet losses and repetitive retransmission timeouts (RTOs) cause severe performance degradation and even service interruption. The loss-tolerant RDMA must avoid “important” packet losses that trigger RTOs. However, existing loss-protection mechanisms fail to identify these packets precisely. They either generate massive misprotection or ignore selective repeat loss recovery, resulting in buffer overflows and failures of RTO protection. To tackle these issues, NüWa thoroughly analyzes distinct loss-recovery schemes and RTO reasons for commodity NICs. It designsswitch modeandNIC modeto accurately identify and protect all important packets. The switch mode inherently supports the widely deployed non-programmable NICs, while the NIC mode offloads identification complexity to advanced programmable NICs. With effective RTO avoidance, it improves flow completion time (FCT) by 2 ∼ 10× compared to state-of-the-art (SOTA) solutions. In severe incast and large-scale networks, it reduces FCT by 100× compared with a lossless fabric. In storage applications, N¨uWa improves IOPS by ∼ 300% compared to vanilla lossy fabric. For typical AI Workloads, it accelerates AllReduce/AlltoAll communication by 5.5 ∼ 13.7× compared to SOTA lossy network solutions.

Diffusion models have achieved remarkable progress in text-to-image generation, enabling the rise of personalized models. A key challenge in personalized generation is to provide users with precise control while ensuring high fidelity to the content. To address this, we introduce VariGen: a framework that empowers users to achieve fine-grained, layout-controllable personalized image generation. VariGen employs the Variational Detail-Aware Feature Extractor to capture intricate details from reference subjects and the Dual Layout Control Mechanism to integrate layout specifications seamlessly into the generation process. We demonstrate that VariGen achieves superior performance through extensive experimentation, offering unparalleled creative freedom and fidelity. To our knowledge, this is the first work to enable users to “create anything, anywhere” with such precision and flexibility.

Large Language Models (LLMs) have greatly pushed forward advancements in natural language processing, yet their high memory and computational demands hinder practical deployment. Binarization, as an effective compression technique, can shrink model weights to just 1 bit, significantly reducing the high demands on computation and memory. However, current binarization methods struggle to narrow the distribution gap between binarized and full-precision weights, while also overlooking the column deviation in LLM weight distribution. To tackle these issues, we propose ARB-LLM, a novel 1-bit post-training quantization (PTQ) technique tailored for LLMs. To narrow the distribution shift between binarized and full-precision weights, we first design an alternating refined binarization (ARB) algorithm to progressively update the binarization parameters, which significantly reduces the quantization error. Moreover, considering the pivot role of calibration data and the column deviation in LLM weights, we further extend ARB to ARB-X and ARB-RC. In addition, we refine the weight partition strategy with column-group bitmap (CGB), which further enhance performance. Equipping ARB-X and ARB-RC with CGB, we obtain ARB-LLM$_{\text{X}}$ and ARB-LLM$ _{\text{RC}} $ respectively, which significantly outperform state-of-the-art (SOTA) binarization methods for LLMs. As a binary PTQ method, our ARB-LLM$ _{\text{RC}} $ is the first to surpass FP16 models of the same size. Code: https://github.com/ZHITENGLI/ARB-LLM.

While super-resolution (SR) methods based on diffusion models (DM) have demonstrated inspiring performance, their deployment is impeded due to the heavy request of memory and computation. Recent researchers apply two kinds of methods to compress or fasten the DM. One is to compress the DM into 1-bit, aka binarization, alleviating the storage and computation pressure. The other distills the multi-step DM into only one step, significantly speeding up inference process. Nonetheless, it remains impossible to deploy DM to resource-limited edge devices. To address this problem, we propose BiMaCoSR, which combines binarization and one-step distillation to obtain extreme compression and acceleration. To prevent the catastrophic collapse of the model caused by binarization, we proposed sparse matrix branch (SMB) and low rank matrix branch (LRM). Both auxiliary branches pass the full-precision (FP) information but in different ways. SMB absorbs the extreme values and its output is high rank, carrying abundant FP information. Whereas, the design of LRMB is inspired by LoRA and is initialized with the top r SVD components, outputting low rank representation. The computation and storage overhead of our proposed branches can be safely ignored. Comprehensive comparison experiments are conducted to exhibit BiMaCoSR outperforms current state-of-the-art binarization methods and gains competitive performance compared with FP one-step model. Moreover, we achieve excellent compression and acceleration. BiMaCoSR achieves a 23.8x compression ratio and a 27.4x speedup ratio compared to FP counterpart. Our code and model are available at https://github.com/Kai-Liu001/BiMaCoSR

Concealed object segmentation (COS) is a challenging problem that focuses on identifying objects that are visually blended into their background. Existing methods often employ reversible strategies to concentrate on uncertain regions but only focus on the mask level, overlooking the valuable of the RGB domain. To address this, we propose a Reversible Unfolding Network (RUN) in this paper. RUN formulates the COS task as a foreground-background separation process and incorporates an extra residual sparsity constraint to minimize segmentation uncertainties. The optimization solution of the proposed model is unfolded into a multistage network, allowing the original fixed parameters to become learnable. Each stage of RUN consists of two reversible modules: the Segmentation-Oriented Foreground Separation (SOFS) module and the Reconstruction-Oriented Background Extraction (ROBE) module. SOFS applies the reversible strategy at the mask level and introduces Reversible State Space to capture non-local information. ROBE extends this to the RGB domain, employing a reconstruction network to address conflicting foreground and background regions identified as distortion-prone areas, which arise from their separate estimation by independent modules. As the stages progress, RUN gradually facilitates reversible modeling of foreground and background in both the mask and RGB domains, reducing false-positive and false-negative regions. Extensive experiments demonstrate the superior performance of RUN and underscore the promise of unfolding-based frameworks for COS and other high-level vision tasks. Code is available at https://github.com/ChunmingHe/RUN.

Multi-player multi-armed bandits (MP-MAB) have been extensively studied due to their application in cognitive radio networks. In this setting, multiple players simultaneously select arms and instantly receive feedback. However, in realistic decentralized networks, feedback is often delayed due to sensing latency and signal processing. Without a central coordinator, explicit communication is impossible, and delayed feedback disrupts implicit coordination, since it depends on synchronous observations. As a result, collisions are frequent and system performance degrades significantly. In this paper, we propose an algorithm in MP-MAB with stochastic delay feedback. Each player in the algorithm independently maintains an estimate of the optimal arm set based on their own delayed rewards but only pulls arms from the set, which is, with high probability, identical to those of other players, thus avoiding collisions. The identical arm set also enables implicit communication, allowing players to utilize the exploration results of others. We establish a regret upper bound and derive a lower bound to prove the algorithm is near-optimal. Numerical experiments on both synthetic and real-world datasets validate the effectiveness of our algorithm.

Vectorized maps are indispensable for precise navigation and the safe operation of autonomous vehicles. Traditional methods for constructing these maps fall into two categories: offline techniques, which rely on expensive, labor-intensive LiDAR data collection and manual annotation, and online approaches that use onboard cameras to reduce costs but suffer from limited performance, especially at complex intersections. To bridge this gap, we introduce the Multiple Roadside Camera-based Vectorized Map approach, MRC-VMap, a cost-effective, vision-centric, end-to-end neural network designed to generate high-definition vectorized maps directly at intersections. Leveraging existing roadside surveillance cameras, MRC-VMap directly converts time-aligned, multi-directional images into vectorized map representations. This integrated solution lowers the need for additional intermediate modules-such as separate feature extraction and Bird’s-Eye View (BEV) conversion steps-thus reducing both computational overhead and error propagation. Moreover, the use of multiple camera views enhances mapping completeness, mitigates occlusions, and provides robust performance under practical deployment constraints. Extensive experiments conducted on 4, 000 intersections across 4 major metropolitan areas in China demonstrate that MRC-VMap not only outperforms state-of-the-art online methods but also achieves accuracy comparable to high-cost LiDAR-based approaches, thereby offering a scalable and efficient solution for modern autonomous navigation systems.

As modern learning-to-rank (LTR) systems rely on both textual and behavioral features, it is essential to extend pre-trained language models (PLMs) from text (queries and webpages) understanding to end-to-end ranking score prediction subject to multiple objectives, such as relevance, quality, authority, and recency. While textual inputs encompass a broader array of features than mere relevance and behavioral features are frequently skewed by user feedback with position bias, an integrated solution is required to jointly disentangle and fuse these heterogeneous features, ensuring robust and unbiased ranking predictions. In this work, we introduce RankExpert, a unified framework that holistically models heterogeneous ranking signals by integrating PLM-based semantic extraction with behavioral cues. RankExpert employs a lightweight PLM with hierarchical distillation for efficient query-document representation, a mixture-of-experts (MoE) architecture to disentangle and optimize objectives across relevance, quality, authority, and recency, and a click expert to mitigate position bias in user feedback within a dual-tower design. Then, RankExpert utilizes an adaptive weight fusion layer to dynamically integrate the outputs of these specialized experts dynamically, aligning ranking predictions with diverse user intents. Extensive offline evaluations on two large-scale real-world datasets reveal that RankExpert significantly outperforms strong competitor models and substantial gains in key performance indicators. Moreover, we deploy RankExpert at Baidu Search and conduct comprehensive online evaluations with real-world web traffic, demonstrating substantial improvements in user satisfaction metrics over the online legacy system and underscoring the practicality of the proposed approach.

While representation learning has been used to boost the performance of Learning-to-Rank (LTR) models through distilling key features for webpage ranking, the weak supervision signals extracted from users' sparse click-through data lead to inadequate representation of query-webpage pairs for ranking score prediction. Recent studies in generative LTR pre-training demonstrate the feasibility of incorporating reconstruction loss for enhanced ranking score prediction. However, LTR is afterall a regression task and it might be reasonable to find an alternate route that pre-trains LTR models with discriminative losses. Following the success of Electra in representation learning for natural language processing (NLP), this work proposes RankElectra that pre-trains the LTR model as a discriminator module inside a generative learning framework. Specifically, RankElectra first structures sparsely-annotated query-webpage pairs into a bipartite graph, with query and webpage feature vectors as node types and ranking scores as the connecting edges, and then leverages positive and negative extension strategies to densify the graph by link predictions. Later, this work proposes a novel Electra module that pre-trains the LTR model as a discriminator module for node reconstruction tasks, where node features of selected edges would be randomly masked and reconstructed by a generator, and the discriminator learns to classify whether the reconstructed features are the original or replaced as well as perform correct ranking. Finally, the pre-trained discriminator module, rather than the generator, would be fine-tuned on the labeled graph. We carried out extensive offline and online evaluations using the real-world web traffic of Baidu search engine. The results show that RankElectra could significantly boost the ranking performance of Baidu Search compared with numbers of competitor systems.

This paper presents Serafin, the first full-stack, sub-mW, and versatile Bluetooth-enabled RF sensor that brings transparent RF sensing to any mobile and IoT device: it independently conducts the whole RF sensing process from RF signal reception to sensing result computation in a wide variety of sensing tasks with only negligible power consumption. At the core of Serafin are our two designs that address the challenge posed by the stringent sub-mW power constraint to jointly achieving versatility and full stackness. Specifically, (i) we utilize the ambient Bluetooth advertising signal as the signal for sensing, and extract the phase difference of the sensing signals received by each antenna pair from the amplitude of their sum signal, which avoids power-hungry hardware components and intensive computation, and (ii) we employ low-power MCU as the computation hardware, and suppress its power consumption by activating it adaptively only when necessary and customizing a light-weight neural network model that still ensures satisfactory inference accuracy. Our extensive experiments on 6 representative sensing tasks show that Serafin achieves competitive sensing performance, but consumes only around 500–900μW power, which is 3–4 orders of magnitude lower than those of existing full-stack and versatile counterparts.

This paper demonstrates Serafin, the first full-stack, sub-mW, and versatile Bluetooth-enabled RF sensor that brings transparent RF sensing to mobile and IoT device: it independently conducts the whole RF sensing process from RF signal reception to sensing result computation in a wide variety of sensing tasks with only negligible power consumption. At the core of Serafin are our two designs that address the challenge posed by the stringent sub-mW power constraint to jointly achieving versatility and full stackness. Specifically, (i) we utilize the ambient Bluetooth advertising signal as the signal for sensing, and extract the phase difference of the sensing signals received by each antenna pair from the amplitude of their sum signal, which avoids power-hungry hardware components and intensive computation, and (ii) we employ low-power MCU as the computation hardware, and suppress its power consumption by activating it only when necessary and customizing a light-weight yet versatile neural network model.

With the rapid growth of Low Earth Orbit (LEO) satellite networks, satellite-IoT systems using the LoRa technique have been increasingly deployed to provide widespread Internet services to low-power and low-cost ground devices. However, the long transmission distance and adverse environments from IoT satellites to ground devices pose a huge challenge to link reliability, as evidenced by the measurement results based on our real-world setup. In this paper, we propose a blind coherent combining design named B2LoRa to boost LoRa transmission performance. The intuition behind B2LoRa is to leverage the repeated broadcasting mechanism inherent in satellite-IoT systems to achieve coherent combining under the low-power and low-cost constraints, where each re-transmission at different times is regarded as the same packet transmitted from different antenna elements within an antenna array. Then, the problem is translated into aligning these packets at a fine granularity despite the time, frequency, and phase offsets between packets in the case of frequent packet loss. To overcome this challenge, we present three designs — joint packet sniffing, frequency shift alignment, and phase drift mitigation to deal with ultra-low SNRs and Doppler shifts featured in satellite-IoT systems, respectively. Finally, experiment results based on our real-world deployments demonstrate the high efficiency of B2LoRa.

Large language models (LLMs) have shown that generative pretraining can distill vast world knowledge into compact token representations. While LLMs encapsulate extensive world knowledge, they remain limited in modeling the behavioral knowledge contained within user interaction histories. User behavior forms a distinct modality, where each action—defined by multi-dimensional attributes such as time, context, and transaction type—constitutes a behavioral token. Modeling these high-cardinality, sparse, and irregular sequences is challenging, and discriminative models often falter under limited supervision. To bridge this gap, we extend generative pretraining to user behavior, learning transferable representations from unlabeled behavioral data analogous to how LLMs learn from text. We present PANTHER, a hybrid generative–discriminative framework that unifies user behavior pretraining and downstream adaptation, enabling large-scale sequential user representation learning and real-time inference. PANTHER introduces: (1) Structured Tokenization to compress multi-dimensional transaction attributes into an interpretable vocabulary; (2) Sequence Pattern Recognition Module (SPRM) for modeling periodic transaction motifs; (3) a Unified User-Profile Embedding that fuses static demographics with dynamic transaction histories, enabling both personalized predictions and population-level knowledge transfer; and (4) Real-time scalability enabled by offline caching of pre-trained embeddings for millisecond-level inference.Fully deployed and operational online at WeChat Pay, PANTHER delivers a 25.6\% boost in next-transaction prediction HitRate@1 and a 38.6\% relative improvement in fraud detection recall over baselines. Cross-domain evaluations on public benchmarks (CCT, MBD, MovieLens-1M, Yelp) show strong generalization, achieving up to 21\% HitRate@1 gains over transformer baselines, establishing PANTHER as a scalable, high-performance framework for industrial user sequential behavior modeling.

Improving Multi-modal Large Language Models (MLLMs) in the post-training stage typically relies on supervised fine-tuning (SFT) or reinforcement learning (RL), which require expensive and manually annotated multi-modal data--an ultimately unsustainable resource. This limitation has motivated a growing interest in unsupervised paradigms as a third stage of post-training after SFT and RL. While recent efforts have explored this direction, their methods are complex and difficult to iterate. To address this, we propose MM-UPT, a simple yet effective framework for unsupervised post-training of MLLMs, enabling continual self-improvement without any external supervision. The training method of MM-UPT builds upon GRPO, replacing traditional reward signals with a self-rewarding mechanism based on majority voting over multiple sampled responses. Our experiments demonstrate that such training method effectively improves the reasoning ability of Qwen2.5-VL-7B (e.g., 66.3\%$\rightarrow$72.9\% on MathVista, 62.9\%$\rightarrow$68.7\% on We-Math), using standard dataset without ground truth labels. To further explore scalability, we extend our framework to a data self-generation setting, designing two strategies that prompt the MLLM to synthesize new training samples on its own. Additional experiments show that combining these synthetic data with the unsupervised training method can also boost performance, highlighting a promising approach for scalable self-improvement. Overall, MM-UPT offers a new paradigm for autonomous enhancement of MLLMs, serving as a critical third step after initial SFT and RL in the absence of external supervision. Our code is available at \url{https://github.com/waltonfuture/MM-UPT}.

Most existing range Searchable Symmetric Encryption (SSE) schemes are static, making them vulnerable to volume pattern leakage attacks. While Volume-Hiding Range SSE (VH-RSSE) was proposed to mitigate such leakage, it does not support dynamic data updates. Dynamic SSE (DSSE) addresses this limitation, but directly combining VH-RSSE with DSSE for range queries presents significant challenges, including: (i) lack of backward privacy support, (ii) inaccurate search results, and (iii) high storage and communication overhead. Moreover, current schemes typically require multiple client-server interactions to perform deletions. In this paper, we introduce a volume-hiding range DSSE scheme that is the first to support non-interactive deletion, while concealing the identifier volumes associated with keyword values during query execution. Specifically, we propose the Revocable Inverted Index (RII), which integrates an order-accumulated inverted index and bitmap structures to efficiently handle range queries. By combining RII with DSSE and symmetric revocable encryption, we enable the client to directly manage ciphertext deletions, thus achieving non-interactive deletion and eliminating the need for additional communication overhead. We provide a formal analysis of the leakage functions to demonstrate that our scheme offers the desired security guarantees. Extensive experimental results show that our approach significantly enhances efficiency when compared to existing solutions.

With the rapid developments of Internet of Thing (IoT) technologies, side-channel sound sensing has become a key research area. Unlike traditional sound-sensing methods that rely on direct acoustic signal recording, side-channel sound-sensing methods utilize various indirect emissions from electronic devices, such as mechanical vibrations, electromagnetic leakage, etc., to infer sound content, making it preferred in many application scenarios. Recently, many works related to side-channel sound sensing have been proposed and drawn much attention from not only academia but also industry. In this article, we present a comprehensive survey of various side-channel sound-sensing methods. Specifically, we first review the commonly sensed object-state characteristics in side-channel sound-sensing methods. Then, we introduce the widely exploited hardware infrastructure, and signal processing techniques, which are the basis of side-channel sound sensing. After that, we provide a categorization introduction of emerging side-channel sound-sensing methods, and review the common application scenarios. Finally, we provide a thoughtful analysis of the countermeasures, challenges, and future directions in this field. With this survey, we aim to summarize the latest research results in the field of side-channel sound sensing and provide insights and inspiration for future research works.

Blockchain-based vehicular edge computing (VEC) is regarded as a promising computing paradigm that can enhance the computing capabilities of mobile vehicles while ensuring security during task offloading. However, the blockchain consensus for secure task offloading inevitably increases the communication and computation resource consumption. More importantly, the frequent handover among roadside units during the fast movement of vehicles also raises the communication cost for blockchain consensus. To address these issues, this article proposes intelligent secure task offloading and caching (ISTOC) scheme for VEC networks. Specifically, we first establish a digital twin-assisted VEC network that migrates the blockchain consensus process from the physical space to the cyber space, supporting the dynamic handover of vehicles. Correspondingly, we propose a lightweight blockchain scheme named diffused delegated Byzantine fault tolerance (d2BFT). Then, aiming at simultaneously reducing the task processing latency and improving the blockchain transaction throughput, we formulate the joint blockchain, communication, computation, and caching (B3C) optimization problem subject to task division, communication bandwidth, computing frequency, cache storage, task deadline, and blockchain stability. Due to the nonconvexity of B3C, we transform it into a Markov decision process, and propose a multiagent double actor-critic (MADAC) algorithm in light of the distributed characteristic of blockchain. Through offline training and online execution, we jointly optimize the task division, communication bandwidth, computing frequency and cache storage allocation, block size, and block generation interval for ISTOC. Experimental results show that the proposed MADAC-based ISTOC scheme can stably converge with a much higher reward than the benchmark schemes based on MADDPG, soft actor-critic, deep deterministic policy gradient, and TD3. The improvement of MADAC-ISTOC over SAC-ISTOC is more than 25.93%.

Real-time industrial video analytics is widely applied across diverse domains within cyber-physical systems (CPS). CPS devices equipped with networked cameras are wirelessly connected to servers for complex vision-based analytics and intelligent operations. Adaptive video streaming is a pivotal technique in these applications to effectively deliver video content to servers under varying network conditions, enabling complex analytics afterward. Our thorough data analysis reveals that conventional offline video streaming control policies cannot effectively adapt to the high dynamics in networks and industrial video scenes. This results in suboptimal analytic performance and necessitates online adaptation for streaming control policy models. Yet, updating control policy models requires ground-truth analytics results which are unavailable directly on end devices due to their limited capacity. Furthermore, naively streaming original videos to the server for online adaptation is greatly challenged by scarce and dynamic networks, leading to decreased accuracy and increased transmission costs. In this paper, we present RIVA, a novel Online Learning-enabled adaptive streaming framework for Real-time Industrial Video Analytics. To facilitate communication-efficient online retraining, we design a hierarchical reinforcement learning approach in which the upper-level module intelligently determines the timing for online retraining, balancing Quality of Service (QoS) improvement and communication cost. Meanwhile, the lower-level module dynamically allocates bitrate to maximize QoS. Extensive experiments based on real-world industrial video and network datasets demonstrate that our proposed framework achieves a 22.6% mean accuracy increase, a 64.9% decrease in the mean failure rate of video uploading, and a 60.2% mean latency decrease compared to the state-of-the-art solutions.

Incompletely-Supervised Concealed Object Segmentation (ISCOS) involves segmenting objects that seamlessly blend into their surrounding environments, utilizing incompletely annotated data, such as weak and semi-annotations, for model training. This task remains highly challenging due to (1) the limited supervision provided by the incompletely annotated training data, and (2) the difficulty of distinguishing concealed objects from the background, which arises from the intrinsic similarities in concealed scenarios. In this paper, we introduce the first unified method for ISCOS to address these challenges. To tackle the issue of incomplete supervision, we propose a unified mean-teacher framework, SEE, that leverages the vision foundation model, "Segment Anything Model (SAM)", to generate pseudo-labels using coarse masks produced by the teacher model as prompts. To mitigate the effect of low-quality segmentation masks, we introduce a series of strategies for pseudo-label generation, storage, and supervision. These strategies aim to produce informative pseudo-labels, store the best pseudo-labels generated, and select the most reliable components to guide the student model, thereby ensuring robust network training. Additionally, to tackle the issue of intrinsic similarity, we design a hybrid-granularity feature grouping module that groups features at different granularities and aggregates these results. By clustering similar features, this module promotes segmentation coherence, facilitating more complete segmentation for both single-object and multiple-object images. We validate the effectiveness of our approach across multiple ISCOS tasks, and experimental results demonstrate that our method achieves state-of-the-art performance. Furthermore, SEE can serve as a plug-and-play solution, enhancing the performance of existing models.

3D Single Object Tracking (SOT) plays an important role in real-world visual applications such as autonomous driving and planning. How to realize effective 3D SOT is still a valuable challenge due to its carrier-sparse point clouds and its role-complex influencing factors. Inspired by the remote modeling of popular transformers, we further propose a Versatile Point Tracking Transformer (VPTT) method for 3D SOT, with object guidance from the template point cloud to the search area point cloud under the siamese-based tracking paradigm. Specifically, VPTT employs self- and cross- attention mechanisms and extends four matching operations, resulting in leveraging the contextual information of consecutive frames to improve the tracking results. By constructing a deep network VerFormer consisting of four successive transformer layers, which performs matching operations involving fusional transformation, separative discrimination, intersectional interaction, and unidirectional propagation from shallow to deep. Considering that the tracking task involves multiple processes, VPTT further learns how to forecast intermediate outputs including mask probability, trailing distance, and heading angle at each stage. Such a specialized design allows our VPTT to revisit the end-to-end training paradigm used for 3D tracking while developing a versatile transformer that is a perfect fit for the 3D SOT task. Experiments on three benchmarks, KITTI, nuScenes, and Waymo, show that VPTT achieves state-of-the-art tracking performance on siamese-based tracking running at $\sim$∼62 FPS.

TrueTime clocks (TTCs) that offer accurate and reliable time within limited uncertainty bounds have been increasingly implemented in many clouds. Multi-region data stores that seek decentralized synchronization for high performance represent an ideal application of TTC. However, the co-designs between the two often failed to realize their full potential. This paper proposes K2, a multi-region data store that explores the opportunity of using TTC for distributed transactions. Compared to its pioneer, Google Spanner, K2 augments TTC's semantics in three core design pillars. First, K2 carries a new timestamp-generating scheme that is capable of providing a small time uncertainty bound at scale. Second, K2 revitalizes existing multi-version timestamp-ordered concurrency control to realize multi-version properties for read-write transactions. Third, K2 introduces a new TTC-based visibility control protocol that provides efficient reads at replicas. Our evaluation shows that, K2 achieves an order of magnitude higher transaction throughput relative to other geo-distributed transaction protocols while ensuring a lower visibility delay at asynchronous replicas.

With the improvement of edge-based autonomous systems such as mobile Industrial IoT (IIoT) networks, edge devices can capture and upload videos with increasing bitrates. Massive edge-computing end nodes are eager for adequate multimedia data to satisfy the requirements of real-time video services. However, existing encoding standards for video services in Web 2.0 are specifically designed for something other than IoT video streaming. We have improved our Adaptive Compression-Reconstruction (ACORN) framework to obtain ACORN+, based on compressed sensing and recent advances in deep learning. At end nodes, we compress multiple sequential video frames into a single frame to reduce video volume. Given that multiple kinds of intelligent tasks are expected to be finished on the device side, we also designed a device-cloud collaboration scheme where deep learning-based algorithms can be executed on both the device and server sides. Experiments reveal that video analytics can be conducted on compressed frames. Taking action recognition as a device-cloud collaboration use case, we find ACORN \(+\) obtains more than 3 \(\times\) speedup on compressed frames. The reconstruction algorithm in ACORN \(+\) is with 1– 4 dB improvements. Moreover, the encoding time cost and the encoded video volume are reduced by more than 4 \(\times\) under the ACORN \(+\) framework. 1

Mixture of experts (MoE) is a popular technique in deep learning that improves model capacity with conditionally-activated parallel neural network modules (experts). However, serving MoE models in resource-constrained latency-critical edge scenarios is challenging due to the significantly increased model size and complexity. In this paper, we first analyze the behavior pattern of MoE models in continuous inference scenarios, which leads to three key observations about the expert activations, including temporal locality, exchangeability, and skippable computation. Based on these observations, we introduce PC-MoE, an inference framework for resource-constrained continuous MoE model serving. The core of PC-MoE is a new data structure,Parameter Committee, that intelligently maintains a subset of important experts in use to reduce resource consumption. To evaluate the effectiveness of PC-MoE, we conduct experiments using state-of-the-art MoE models on common computer vision and natural language processing tasks. The results demonstrate optimal trade-offs between resource consumption and model accuracy achieved by PC-MoE. For instance, on object detection tasks with the Swin-MoE model, our approach can reduce memory usage and latency by 42.34% and 18.63% with only 0.10% accuracy degradation.

Existing 3D mask learning methods encounter performance bottlenecks under limited data, and our objective is to overcome this limitation. In this paper, we introduce a triple point masking scheme, named TPM, which serves as a scalable plug-and-play framework for MAE pre-training to achieve multi-mask learning for 3D point clouds. Specifically, we augment the baseline methods with two additional mask choices (i.e., medium mask and low mask) as our core insight is that the recovery process of an object can manifest in diverse ways. Previous high-masking schemes focus on capturing the global representation information but lack fine-grained recovery capabilities, so that the generated pre-training weights tend to play a limited role in the fine-tuning process. With the support of the proposed TPM, current methods can exhibit more flexible and accurate completion capabilities, enabling the potential autoencoder in the pre-training stage to consider multiple representations of a single 3D point cloud object. In addition, during the fine-tuning stage, an SVM-guided weight selection module is proposed to fill the encoder parameters for downstream networks with the optimal weight, maximizing linear accuracy and facilitating the acquisition of intricate representations for new objects. Extensive experimental results and theoretical analysis show that five baselines equipped with the proposed TPM achieve comprehensive performance improvements on various downstream tasks. Our code and models are available athttps://github.com/liujia99/TPM.

3D Gaussian splatting (3DGS) suggests the use of explicit point-based 3D representations for high-fidelity novel view synthesis, with training and rendering speeds that are better than prior neural radiance fields. However, 3DGS relies heavily on synthetic point clouds generated by structure from motion (SfM) or multi view stereo (MVS) techniques, and lacks a well-defined method to initially condition them. In this work, we first propose a mesh-aligned method that attaches the 3D Gaussian to the extracted surface meshes for reliable initialization during training, and then directly manipulates the learnable 3DGS in the local coordinate using the triangular meshes. In addition, to constrain the stereo Gaussian on a planar mesh for better rendering, both normal and depth losses are designed to optimize the orientation and significance of the Gaussian. In practice, we further apply this method to multi-resolution scene rendering while resolving the aliasing effect. Unlike directly changing the size and number of Gaussians that may interfere the rendering quality at different resolutions, we argue that the properties of the modelled mesh are naturally resistant to aliasing effects. By utilising triangular meshes for Gaussian binding and adaptive learning, the proposed method can maintain high-fidelity rendering after splatting on multi-resolution concrete images. Extensive experiments demonstrate the effectiveness of our approach and its advantages over single full-resolution baseline.

The recently proposed Join Cross-Tags Protocol (JXT) addresses the long-standing issue of excessive query overhead in table joins within Searchable Symmetric Encryption (SSE). As a purely symmetric-key solution, JXT supports efficient conjunctive queries over equi-joins of encrypted tables without requiring any pre-computation during the setup phase. However, JXT has a potential limitation: it may inadvertently reveal the actual volumes of identifiers corresponding to attribute-value pairs, as well as the result values of the join queries. In this paper, we propose JXTMM (JXT multi-map), the first join query scheme designed to hide both volume patterns and result patterns. JXTMM is capable of concealing identifier volumes, preventing the server from learning the actual volumes of attribute-value pairs, and shifting the checkability of join results to the client side, thereby eliminating result pattern leakage. We provide a formal security proof for JXTMM, along with a comprehensive efficiency analysis. Experimental results demonstrate that JXTMM not only performs efficiently on table join queries but also effectively achieves volume-hiding in such queries.

The map matching of cellular data reconstructs real trajectories of users by exploiting the sequential connections between mobile devices and cell towers. The difficulty in obtaining paired cellular-GPS data and the cellular variation compromise the accuracy and reliability of existing map matching approaches. In this paper, we propose a novelunsupervisedconvolutional network for cellularmapmatching (UCMM) to address these challenges. UCMM employs a dual encoder-decoder network to capture a shared representation from both the cellular and GPS domains in an unsupervised manner. It leverages a dedicated convolutional architecture to tackle the varying lengths of output sequential data. An attention mechanism is specially introduced to deal with the cellular variation. The effectiveness of UCMM is demonstrated through comprehensive evaluations, which show that UCMM achieves a substantial improvement in matching accuracy and deduction of training time compared with the best-known prior works. These improvements make UCMM a significant advancement in the field of map matching.

As one of the most essential accessories, headsets have been widely used in common online conversations. The metal coil vibration patterns of headset speakers/microphones have been proven to be highly correlated with the speaker-produced/microphone-received sound. This paper presents an online conversation eavesdropping system,RFSpy, which uses only one RFID tag attached on a headset to alternately sense metal coil vibrations of headset speaker and microphone for eavesdropping on speaker-produced and microphone-received sound. In some accessible scenarios, assuming attackers secretly attach a small, battery-free RFID tag under one ear cushion of an eavesdropped user’s headset without being noticed. Meanwhile, RFID readers are camouflaged as decorations placed in/out of rooms to transmit and receive RF signals. When the eavesdropped user talks with other users online through the headset,RFSpyfirst activates the RFID tag to capture the metal coil vibration patterns of headset speaker and microphone upon RF signals. Then,RFSpyreconstructs sound spectrograms from the RF signal-based vibration patterns for not only trained words but also untrained (i.e., out-of-vocabulary) words utilizing designed SSR network. Finally,RFSpyconverts the sound spectrograms to conversation content through sound recognition API. Extensive experiments demonstrate thatRFSpycan eavesdrop on online conversations with out-of-vocabulary words effectively.

The technology of facial expression reconstruction has paved the way for various face-centric applications such as virtual reality (VR) modeling, human-computer interaction, and affective computing. Existing vision-based solutions present challenges in privacy leakage and poor lighting conditions. In this paper, we introduce a nonintrusive facial expression reconstruction system,mm3DFace, which uses a millimeter wave (mmWave) radar to reconstruct facial expressions in a privacy-preserving and passive manner.mm3DFacefirst captures and pre-processes mmWave signals reflected by a human face, and extracts intricate facial geometric features using a ConvNeXt model integrated with triple loss embedding. Subsequently,mm3DFacederives pose-invariant facial representations utilizing region-divided affine transformation, and further generates individual facial shapes with 68 facial landmarks. Then, dynamic facial expressions with 3D facial avatars are reconstructed to exhibit realistic facial expressions. Finally,mm3DFaceenables micro-expression recognition with mmWave signals, which ensures the capability of describing tiny facial changes. Through extensive real-world experiments involving 15 participants,mm3DFaceachieves a normalized mean error of 3.94%, a mean absolute error of 2.30 mm, and a 3D-mean absolute error of 4.10 mm in tracking 68 facial landmarks, which demonstrates the efficacy and practicality ofmm3DFacein real-world 3D facial reconstruction scenarios.

User authentication is evolving with expanded applications and innovative techniques. New authentication approaches utilize RF signals to sense specific human characteristics, offering a contactless and nonintrusive solution. However, these RF signal-based methods struggle with challenges in open-world scenarios, i.e., dynamic environments, daily behaviors with unrestricted postures, and identification of unauthorized users with security threats. In this paper, we present an open-world user authentication system, OpenAuth, which leverages a commercial off-the-shelf (COTS) mmWave radar to sense unrestricted human postures and behaviors for identifying individuals. First, OpenAuth utilizes a MUSIC-based neural network imaging model to eliminate environmental clutter and generate environment-independent human silhouette images. Then, the human silhouette images are normalized to consistent topological structures of human postures, ensuring robustness against unrestricted human postures. Next, fine-grained body features are extracted from these environment-independent and posture-independent human silhouette images using a metric learning model. To eliminate potential security threats that arise from unauthorized users, OpenAuth synthesizes data placeholders for enhancing unauthorized user identification. Finally, a k-NN-based authentication model is constructed to authenticate users' identities. Experiments in real environments show that the proposed OpenAuth achieves an average authentication accuracy of 93.4% and false acceptance rate (FAR) of 1.8% in open-world scenarios.

There has been a growing interest in applying machine learning to real-world tasks. However, due to the black-box nature of machine learning models, it is crucial to 1) verify important properties of a model and 2) understand the reasons behind a model’s prediction before deploying them in a production environment. Existing approaches typically handle them as two separate and sometimes orthogonal topics. In this paper, we show that the verification and interpretability of machine learning models are tightly related and can be unified by satisfiability modulo theories (SMT). Our key insight is: not only a wide range of properties of machine learning models can be formulated as SMT problems and verified accordingly, but many commonly studied interpretability questions can also be answered by iteratively checking the satisfiability and related properties of multiple SMT problems. Leveraging this insight, we design UINT, a general verification and interpretability framework for learning-based networking systems. UINT 1) allows operators to specify verification and interpretability problems as SMT formulas, 2) encodes the target machine learning models into SMT constraints, and 3) automatically simplifies and solves the corresponding verification and interpretability problems using commodity SMT solvers. We implement a prototype of UINT and evaluate it on real-world learning-based networking systems. Results demonstrate the efficiency and efficacy of UINT in verifying and interpreting key questions for these systems.

Inter-Satellite Links (ISLs) are pivotal for delivering global connectivity services and optimizing resource utilization in 6 G and beyond. However, delivering effective topology control services through ISL provisioning faces critical challenges insustainabilityandreliability. Reducing ISLs can conserve energy and extend satellite battery life for Low-Earth-Orbit (LEO) satellites where replacing batteries is impractical. Conversely, increasing ISLs can enhance service reliability but may lead to uneven traffic distribution, overloading nodes, and accelerating battery degradation, ultimately degrading the quality of 6 G services. To tackle this dilemma, we propose TASRI—a service-oriented framework forTraffic-Aware, Sustainable, and Reliable ISL provisioning. TASRI provides a dynamic topology control service by partitioning network topologies into logical zones, enabling flexible ISL activation and deactivation to adapt to varying service demands, ensuring efficient resource utilization and dynamic service orchestration. Using a sustainability-oriented weight model, we formulate the topology control service optimization problem and introduce a scalable on-demand topology evolving algorithm with a bounded approximation ratio. Extensive real-world deployment-based simulation results show that, compared to the state-of-the-art, our TASRI can substantially reduce battery life consumption, while achieving comparable reliability and excellent scalability with considerably fewer ISLs or ISL handovers.

Serverless computing has become increasingly popular due to its flexible and hassle-free service, relieving users from traditional resource management burdens. However, the shift in responsibility has led to unprecedented challenges for serverless providers in managing virtual machines (VMs) and serving heterogeneous function instances. Serverless providers need to purchase, provision and manage VM instances from IaaS providers, aiming to minimize VM provisioning costs while ensuring compliance with Service Level Objectives (SLOs). In this paper, we propose Trident, a provider-oriented resource management framework for serverless computing platforms. Trident optimizes three major serverless computing provisioning problems for serverless providers: workload prediction, VM provisioning, and function placement. Specifically, Trident introduces a novel dynamic model selection algorithm for more accurate workload prediction. With the prediction results, Trident then carefully designs a hierarchical reinforcement learning (HRL)-based approach for VM provisioning with a mix of types and configurations. To further improve resource utilization, Trident employs an effective collocation placement strategy for efficient function container scheduling. Evaluations on the Azure Function dataset demonstrate that Trident maintains the lowest probability of violating SLOs while simultaneously achieving substantial cost savings of up to 71.8% in provisioning expense compared to state-of-the-art methods from industry and academia.

Wireless train communication network (WLTCN) is an emerging technology for enabling intelligent rail vehicles. It is responsible for providing train control services (TCS), passenger information services (PIS), and train sensing services (TSS). These services within WLTCN have notably different quality of service (QoS) requirements from traditional telecommunication services. In this paper, to incorporate multiple services in a single WLTCN, we propose a radio access network (RAN) slicing architecture empowered WLTCN to satisfy the demands of services and save bandwidth resource. In particular, the service and slicing models of TCS, PIS, and TSS are investigated. By analyzing the heterogeneous characteristics and QoS requirements of the above services within WLTCN, we exploit the orthogonal multiple access scheme for TCS and PIS and the non-orthogonal multiple access scheme for TSS, respectively. The system bandwidth minimization problem is formulated with slicing resource allocation for TCS, PIS, and TSS and non-orthogonal access grouping for TSS terminals as a mixed-integer nonlinear programming (MINLP). To solve the intractable MINLP, the original problem is transformed and decoupled into the two subproblems. Then, we propose a joint bandwidth optimization and terminal clustering (JBOTC) algorithm to tackle the bandwidth allocation problem with optimal terminal grouping strategy for TSS effectively. The closed-form expressions of the optimal bandwidth allocation strategy for three services are derived. The simulation results illustrate the performance superiority for saving bandwidth of the JBOTC algorithm to the benchmark schemes. Our proposed slicing strategy enables WLTCN to support heterogeneous services co-existence with minimal bandwidth consumption.

Rui Kong, Yuanchun Li, Qingtian Feng, Weijun Wang, Xiaozhou Ye, Ye Ouyang, Linghe Kong, Yunxin Liu. Proceedings of the 62nd Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers). 2024.

DNS misconfiguration can result in severe social and financial consequences. Existing DNS configuration verification tools employ a centralized architecture, where all zone files are collected for verification. This architecture faces significant scalability issues (e.g., the verifier becoming the performance bottleneck and not supporting incremental verification). Inspired by the recent proposal of distributed data plane verification and the resemblance between the network data plane and DNS configuration, we propose to rearchitect DNS configuration verification with a distributed design. Our key insight is that by analyzing the query processing behavior of each DNS zone file in parallel and stitching the results in a symbolic way, we can substantially scale up the verification of DNS configuration. Evaluation shows that an up to 9.51× speed up on a dataset with over 410,000 resource records while having small overhead.

Hand pose estimation is a key support for a variety of interactive applications including user interface control, sign language understanding, virtual reality modeling, etc. Existing approaches mainly exploit wearable devices such as gloves or bracelets to estimate hand poses, which may introduce high deploying costs and intrusive user experience. Others rely on vision technologies whereas they could face complicated illuminations and privacy leakage. In this paper, we present a millimeter wave (mmWave) signal-based 3D hand pose estimation system, mmHand, which utilizes a mmWave radar to generate 3D hand skeletons and reconstruct 3D hand meshes. mmHand first leverages mmWave signals to sense a hand and pre-process the signals. Then, mmHand extracts spatial and temporal features using a designed attention-based hourglass network (mmSpaceNet) and Long Short-Term Memory (LSTM), respectively. Based on the extracted features, mmHand further regresses hand joints in 3D space to generate 3D hand skeletons. Finally, 3D hand meshes that continuously describe hand poses with detailed surfaces are reconstructed through a hand Model with Articulated and Non-rigid defOrmations (MANO). Extensive experiments demonstrate that mmHand can accurately generate 3D hand skeletons with 18.3mm mean per joint position error and 95.1 % of correct key points, which indicates the effectiveness of mmHand on hand pose estimation.

User authentication is evolving with expanded application scenarios and innovative techniques. New authentication approaches utilize RF signals to sense specific human behaviors and characteristics, such as faces, specific gestures, etc., offering a contactless and nonintrusive solution. However, these RF signal-based methods struggle with challenges in open-world scenarios, i.e., dynamic environments, daily behaviors with unrestricted postures, and identification of unauthorized users with security threats. In this paper, we present an open-world user authentication system, OpenAuth, which leverages a commercial off-the-shelf (COTS) mmWave radar to sense unrestricted human postures and behaviors for identifying individuals. First, OpenAuth utilizes a MUSIC-based neural network imaging model to eliminate environmental clutter and generates environment-independent human silhouette images. Then, the human silhouette images are normalized to consistent topological structures of human postures, ensuring robustness against unrestricted human postures. Based on the environment-independent and posture-independent human silhouette images, OpenAuth further extracts fine-grained body features through a metric learning model for user authentication. To eliminate potential security threats that arise from frequent accesses by unauthorized users, OpenAuth synthesizes data placeholders for enhancing the applicability of unauthorized user identification. Finally, a k-NN-based authentication model is constructed based on the extracted body features to authenticate users' identities. Experiments in real environments show that the proposed OpenAuth achieves an average authentication accuracy of 93.4 % and false acceptance rate (FAR) of 1.8% in open-world scenarios.

Transformer architectures have exhibited remarkable performance in image super-resolution (SR). Since the quadratic computational complexity of the self-attention (SA) in Transformer, existing methods tend to adopt SA in a local region to reduce overheads. However, the local design restricts the global context exploitation, which is crucial for accurate image reconstruction. In this work, we propose the Recursive Generalization Transformer (RGT) for image SR, which can capture global spatial information and is suitable for high-resolution images. Specifically, we propose the recursive-generalization self-attention (RG-SA). It recursively aggregates input features into representative feature maps, and then utilizes cross-attention to extract global information. Meanwhile, the channel dimensions of attention matrices ($query$, $key$, and $value$) are further scaled to mitigate the redundancy in the channel domain. Furthermore, we combine the RG-SA with local self-attention to enhance the exploitation of the global context, and propose the hybrid adaptive integration (HAI) for module integration. The HAI allows the direct and effective fusion between features at different levels (local or global). Extensive experiments demonstrate that our RGT outperforms recent state-of-the-art methods quantitatively and qualitatively. Code and pre-trained models are available at https://github.com/zhengchen1999/RGT.

In this paper, we present a hybrid X-shaped vision Transformer, named Xformer, which performs notably on image denoising tasks. We explore strengthening the global representation of tokens from different scopes. In detail, we adopt two types of Transformer blocks. The spatial-wise Transformer block performs fine-grained local patches interactions across tokens defined by spatial dimension. The channel-wise Transformer block performs direct global context interactions across tokens defined by channel dimension. Based on the concurrent network structure, we design two branches to conduct these two interaction fashions. Within each branch, we employ an encoder-decoder architecture to capture multi-scale features. Besides, we propose the Bidirectional Connection Unit (BCU) to couple the learned representations from these two branches while providing enhanced information fusion. The joint designs make our Xformer powerful to conduct global information modeling in both spatial and channel dimensions. Extensive experiments show that Xformer, under the comparable model complexity, achieves state-of-the-art performance on the synthetic and real-world image denoising tasks. We also provide code and models at https://github.com/gladzhang/Xformer.

Satisfiability Modulo Theories (SMT) based network configuration verification tools are powerful tools in preventing network configuration errors. However, their fundamental limitation is efficiency, because they rely on generic SMT solvers to solve SMT problems, which are in general NP-complete. In this paper, we show that by leveraging network domain knowledge, we can substantially accelerate SMT-based network configuration verification. Our key insights are: given a network configuration verification formula, network domain knowledge can (1) guide the search of solutions to the formula by avoiding unnecessary search spaces; and (2) help simplify the formula, reducing the problem scale. We leverage these insights to design a new SMT- based network configuration verification tool called NetSMT. Extensive evaluation using real-world topologies and synthetic network configurations shows that NetSMT achieves orders of magnitude improvements compared to state-of-the-art methods.

Inter-Satellite Links (ISLs) are key for worldwide communication and efficient use of space networks in the future 6G network. However, they face challenges in sustainability and reliability. Reducing ISLs saves energy and extends battery life, which is critical since satellite batteries are hard to replace. More ISLs, however, can make the system more reliable but at the cost of higher energy use, especially problematic when traffic is uneven, speeding up battery wear. To tackle this dilemma, we for the first time develop a Traffic-Aware, Sustainable and Reliable ISL provisioning (TASRI) framework for LEO satellite constellation networks. In TASRI, ISLs can be flexibly switched on and off to better accommodate various traffic conditions as well as reliability and sustainability. We formulate the ISL provisioning problem based on the sustainability-oriented weight model and then propose an on-demand topology evolving algorithm. Extensive real-world deployment-based simulation results show that, compared to the state-of-the-art, our TASRI can substantially reduce battery life consumption, while achieving comparable reliability with considerably fewer ISLs.

Enabling low-latency end-to-end interdomain communication is critical in edge networks. However, the current network architecture results in unnecessarily long communication paths, leading to high latency between devices. To address this issue, we propose a novel interdomain edge peering framework called Collie. In Collie, edge networks belonging to different network providers collaborate to forward traffic towards destinations, effectively reducing end-to-end communication latency. Importantly, Collie allows network providers to maintain their autonomy in link usage strategy. We also develop a distributed algorithm in Collie that enables edge nodes from different networks to collectively determine optimal routing and traffic assignment, ensuring low-latency delivery while respecting network policies without exposing them. We implement a prototype of Collie and extensively evaluate its performance using real-world topologies. Our results demonstrate that Collie achieves a tight approximation ratio and exhibits scalability in large interdomain edge networks.

Eavesdropping on human sound is one of the most common but harmful ways to threaten personal privacy. As one of the most essential accessories, headsets have been widely used in common online conversations, such as online calls, video meetings, etc. The metal coil vibration patterns of headset speakers/microphones have been proven to be highly correlated with the speaker-produced/microphone-received sound content. This paper presents an online conversation eavesdropping system, RFSpy, which uses only one RFID tag attached on a headset to alternately sense the metal coil vibrations of headset speaker and microphone for eavesdropping on speaker-produced and microphone-received sound. In some accessible scenarios, such as meeting rooms, offices, etc., assuming attackers secretly attach a small, battery-free RFID tag under one ear cushion of an eavesdropped user's headset without being noticed. Meanwhile, RFID readers are camouflaged as decorations placed in/out of rooms to transmit and receive RF signals. When the eavesdropped user talks with other users online by using the headset, RFSpy first activates the RFID tag attached on the headset to capture the metal coil vibration patterns of headset speaker and microphone upon RF signals. Then, RFSpy reconstructs sound spectrograms from the RF signal-based vibration patterns for not only trained words but also untrained (i.e., out-of-vocabulary) words by utilizing a designed Sound Spectrogram Reconstruction (SSR) network. Finally, RFSpy converts the sound spectrograms to conversation content through a sound recognition API. Extensive experiments in real environments demonstrate that RFSpy can eavesdrop on online conversations with out-of-vocabulary (OOV) words effectively.

The Internet of Things (IoT) has expanded its reach through applications like environmental monitoring and smart agriculture. Its growth is often limited by the need for extensive IoT gateways and base stations. Satellite-based IoT, using low Earth orbit (LEO) satellites, offers a solution by enabling global sensing without terrestrial infrastructure. This technology allows IoT devices to transmit data to satellite gateways, which is crucial for dynamic environments like the ocean where nodes drift with currents. In such applications, position information is valuable for data analysis and tracing. Traditional GPS modules, while affordable and low-energy, can be inefficient due to the large payload space required for precise positioning data. The payload used to report the position might be as long as the sensed data itself. This paper proposes a novel approach to terrestrial IoT device positioning using LoRa or FSK modulation, where positioning is performed on the satellite, saving GPS bytes and reducing packet size. By utilizing Doppler effects and satellite motion, the method calculates device positions, forming a positioning equation set without interfering with communication tasks. Challenges in Doppler effect measurement and positioning are addressed with a fine-grained frequency shift measurement method using ZoomFFT and zero-padding FFT, and a non-linear equation set is solved to determine the positions of terrestrial nodes, with constraints added to ensure practical solutions. The framework is validated through simulations, demonstrating a significant reduction in payload length and positioning accuracy comparable to GPS. In ideal cases, the framework can locate nodes with errors less than 60 meters without any GPS information from data packets.

Advanced diffusion models (DMs) perform impressively in image super-resolution (SR), but the high memory and computational costs hinder their deployment. Binarization, an ultra-compression algorithm, offers the potential for effectively accelerating DMs. Nonetheless, due to the model structure and the multi-step iterative attribute of DMs, existing binarization methods result in significant performance degradation. In this paper, we introduce a novel binarized diffusion model, BI-DiffSR, for image SR. First, for the model structure, we design a UNet architecture optimized for binarization. We propose the consistent-pixel-downsample (CP-Down) and consistent-pixel-upsample (CP-Up) to maintain dimension consistent and facilitate the full-precision information transfer. Meanwhile, we design the channel-shuffle-fusion (CS-Fusion) to enhance feature fusion in skip connection. Second, for the activation difference across timestep, we design the timestep-aware redistribution (TaR) and activation function (TaA). The TaR and TaA dynamically adjust the distribution of activations based on different timesteps, improving the flexibility and representation alability of the binarized module. Comprehensive experiments demonstrate that our BI-DiffSR outperforms existing binarization methods. Code is released at: https://github.com/zhengchen1999/BI-DiffSR.

\textit{Dataset condensation} is a newborn technique that generates a small dataset that can be used in training deep neural networks (DNNs) to lower storage and training costs. The objective of dataset condensation is to ensure that the model trained with the synthetic dataset can perform comparably to the model trained with full datasets. However, existing methods predominantly concentrate on classification tasks, posing challenges in their adaptation to time series forecasting (TS-forecasting). This challenge arises from disparities in the evaluation of synthetic data. In classification, the synthetic data is considered well-distilled if the model trained with the full dataset and the model trained with the synthetic dataset yield identical labels for the same input, regardless of variations in output logits distribution. Conversely, in TS-forecasting, the effectiveness of synthetic data distillation is determined by the distance between predictions of the two models. The synthetic data is deemed well-distilled only when all data points within the predictions are similar. Consequently, TS-forecasting has a more rigorous evaluation methodology compared to classification. To mitigate this gap, we theoretically analyze the optimization objective of dataset condensation for TS-forecasting and propose a new one-line plugin of dataset condensation for TS-forecasting designated as Dataset \textbf{Cond}ensation for \textbf{T}ime \textbf{S}eries \textbf{F}orecasting (CondTSF) based on our analysis. Plugging CondTSF into previous dataset condensation methods facilitates a reduction in the distance between the predictions of the model trained with the full dataset and the model trained with the synthetic dataset, thereby enhancing performance. We conduct extensive experiments on eight commonly used time series datasets. CondTSF consistently improves the performance of all previous dataset condensation methods across all datasets, particularly at low condensing ratios.

While Distributed Machine Learning (DML) has been widely used to achieve decent performance, it is still challenging to take full advantage of data and devices distributed at multiple vantage points to adapt and learn, especially it is non-trivial to address dynamic and divergence challenges based on the linear aggregation framework as follows: (1) heterogeneous learning data at different devices (i.e., non-IID data) resulting in model divergence and (2) in the case of time-varying communication links, the limited ability for devices to reconcile model divergence. In this paper, we contribute a non-linear class aggregation framework HyperPrism that leverages distributed mirror descent with averaging done in the mirror descent dual space and adapts the degree of Weighted Power Mean (WPM) used in each round. Moreover, HyperPrism could adaptively choose different mapping for different layers of the local model with a dedicated hypernetwork per device, achieving automatic optimization of DML in high divergence settings. We perform rigorous analysis and experimental evaluations to demonstrate the effectiveness of adaptive, mirror-mapping DML. In particular, we extend the generalizability of existing related works and position them as special cases within HyperPrism. Our experimental results show that HyperPrism can improve the convergence speed up to 98.63% and scale well to more devices compared with the state-of-the-art, all with little additional computation overhead compared to traditional linear aggregation.

Low-bit quantization has become widespread for compressing image super-resolution (SR) models for edge deployment, which allows advanced SR models to enjoy compact low-bit parameters and efficient integer/bitwise constructions for storage compression and inference acceleration, respectively. However, it is notorious that low-bit quantization degrades the accuracy of SR models compared to their full-precision (FP) counterparts. Despite several efforts to alleviate the degradation, the transformer-based SR model still suffers severe degradation due to its distinctive activation distribution. In this work, we present a dual-stage low-bit post-training quantization (PTQ) method for image super-resolution, namely 2DQuant, which achieves efficient and accurate SR under low-bit quantization. The proposed method first investigates the weight and activation and finds that the distribution is characterized by coexisting symmetry and asymmetry, long tails. Specifically, we propose Distribution-Oriented Bound Initialization (DOBI), using different searching strategies to search a coarse bound for quantizers. To obtain refined quantizer parameters, we further propose Distillation Quantization Calibration (DQC), which employs a distillation approach to make the quantized model learn from its FP counterpart. Through extensive experiments on different bits and scaling factors, the performance of DOBI can reach the state-of-the-art (SOTA) while after stage two, our method surpasses existing PTQ in both metrics and visual effects. 2DQuant gains an increase in PSNR as high as 4.52dB on Set5 (x2) compared with SOTA when quantized to 2-bit and enjoys a 3.60x compression ratio and 5.08x speedup ratio. The code and models are available at https://github.com/Kai-Liu001/2DQuant.

The rapid progression of urbanization has generated a diverse array of urban data, facilitating significant advancements in urban science and urban computing. Current studies often work on separate problems case by case using diverse data, e.g., air quality prediction, and built-up areas classification. This fragmented approach hinders the urban research field from advancing at the pace observed in Computer Vision and Natural Language Processing, due to two primary reasons. On the one hand, the diverse data processing steps lead to the lack of large-scale benchmarks and therefore decelerate iterative methodology improvement on a single problem. On the other hand, the disparity in multi-modal data formats hinders the combination of the related modal data to stimulate more research findings. To address these challenges, we propose UrbanDataLayer (UDL), a suite of standardized data structures and pipelines for city data engineering, providing a unified data format for researchers. This allows researchers to easily build up large-scale benchmarks and combine multi-modal data, thus expediting the development of multi-modal urban foundation models. To verify the effectiveness of our work, we present four distinct urban problem tasks utilizing the proposed data layer. UrbanDataLayer aims to enhance standardization and operational efficiency within the urban science research community. The examples and source code are available at https://github.com/SJTU-CILAB/udl.

Blockchain and smart contracts are one of the key technologies promoting Web 3.0. However, due to security considerations and consistency requirements, smart contracts currently only support simple and deterministic programs, which significantly hinders their deployment in intelligent Web 3.0 applications. To enhance smart contracts intelligence on the blockchain, we propose SMART, a plug-in smart contract framework that supports efficient AI model inference while being compatible with existing blockchains. To handle the high complexity of model inference, we propose an on-chain and off-chain joint execution model, which separates the SMART contract into two parts: the deterministic code still runs inside an on-chain virtual machine, while the complex model inference is offloaded to off-chain compute nodes. To solve the non-determinism brought by model inference, we leverage Trusted Execution Environments (TEEs) to endorse the integrity and correctness of the off-chain execution. We also design distributed attestation and secret key provisioning schemes to further enhance the system security and model privacy. We implement a SMART prototype and evaluate it on a popular Ethereum Virtual Machine (EVM)-based blockchain. Theoretical analysis and prototype evaluation show that SMART not only achieves the security goals of correctness, liveness, and model privacy, but also has approximately 5 orders of magnitude faster inference efficiency than existing on-chain solutions.

Wireless Sensor Networks (WSNs), which provide perception services for the Internet of Things (IoT) infrastructure, usually suffer from constrained energy resources. However, the fact that the data collected by WSNs often exhibit spatial-temporal correlation leads to the waste of energy. In addition, load imbalance among sensor nodes also makes energy efficiency low. To this end, a novel Energy-efficient approach based on Clustering using Grey Prediction (ECGP) is proposed in this paper. To be specific, a novel Dual-end Data Prediction Mechanism (DDPM) is presented based on the grey prediction model to cut down data redundancy. Furthermore, the prediction process of the grey model, namely a dynamic and fixed size prediction queue scheme, is optimized to enhance the prediction accuracy. A novel Energy-Distance Factor (EDF) and a novel Dual-Threshold-based Critical Condition (DTCC) are proposed with the aim of realizing load balance and alleviating the challenge resulted from random events occurrence. Finally, extensive experimental simulations have been carried out to demonstrate the energy efficiency of ECGP. It is compared with the classic and several latest clustering algorithms, namely, LEACH, R-LEACH, EAHA and ECPSO. The experimental results indicate that ECGP outperforms the others in terms of the network lifetime, the throughput, and the energy efficiency.

Task offloading (TO) is beneficial to reducing the delay and energy consumption for the prosperity of the applications in next generation (NG) wireless networks. However, existing TO approaches are inability to exhibit low complexity and stable performance. To this end, a novel federated hierarchical deep deterministic policy gradient (FHDDPG) algorithm for TO and resource allocation (RA) is proposed in this article. To be specific, three deep deterministic policy gradient (DDPG) modules are deployed in parallel to make offloading decision on the execution mode of tasks and the proportion allocation of the transmission rate. Subsequently, a federated learning method is proposed to collaboratively train the HDDPG model by means of sharing models’ weights. Meanwhile, the delay and the energy consumption are comprehensively considered as the average system consumption, which is defined as a reward metric of FHDDPG. Finally, extensive simulations are conducted to demonstrate the effectiveness of our proposal. The experimental results indicate that the average system consumption of FHDDPG is cut down by 11.4% and 18% compare with HDDPG and DDPG, respectively, which means FHDDPG can achieve a better performance effectively.

With the emergence of the sixth-generation (6G) communication technologies, the Internet of Vehicles (IoV) is rapidly developing with the coordination between intelligent networked vehicles, road infrastructures, and the cloud. However, the openness and dynamic nature of the IoV raise significant security and privacy concerns, highlighting the need for efficient authentication schemes. Conventional authentication schemes are no longer suitable for 6G-enabled IoV due to high latency, single point of failure, and heavy management costs. Additionally, existing literature on multi-domain authentication mainly investigates vehicle mobility, ignoring the challenges posed by vehicle heterogeneity. To fill this gap, we propose a multi-domain authentication scheme with conditional privacy preservation (MACPP) that considers administrative domains (AD) and geographic domains (GD) in the IoV. In MACPP, we design a novel identity-based signature scheme without requiring bilinear pairing for efficient authentication. Additionally, we propose a blockchain-assisted pseudonym management scheme (BAPM) to further improve system security by designing a dynamical sparse Merkle tree structure (DSMT). We demonstrate that the proposed MACPP satisfies the security requirements through an in-depth security analysis. Moreover, the experimental results demonstrate the effectiveness and efficiency of both MACPP and BAPM.

Gait-based user authentication schemes have been widely explored because of their ability of non-invasive sensing and avoid replay attacks. However, existing gait-based user authentication methods are environment-dependent. In this paper, we present an environment-independent gait-based user authentication system,RFPass, which can identify different individuals leveraging RFID signals. Specifically, we find that Doppler shift of RF signals can describe environment-independent gait features for different individuals. InRFPass, when a user walks through theRFPasssystem, RF signals are first collected by a deployed RFID tag array. Then,RFPassremoves environmental interference from the collected RF signals through a proposed Multipath Direction of arrival (DoA) Signal Select (MDSS) algorithm, and further constructs the environment-independent gait profile. Afterwards, environment-independent gait features are extracted from the constructed gait profile by a proposed CNN-RNN model. Based on the extracted gait features, a hierarchical classifier is trained for user authentication and spoofer detection. Extensive experiments in different real environments demonstrate thatRFPasscan achieve environment-independent gait-based user authentication.

Mobile crowdsensing (MCS) can promote data acquisition and sharing among mobile devices. Traditional MCS platforms are based on a triangular structure consisting of three roles: data requester, worker (i.e. , sensory data provider) and MCS platform. However, this centralized architecture suffers from poor reliability and difficulties in guaranteeing data quality and privacy, even provides unfair incentives for users. In this paper, we propose a blockchain-based MCS platform, namely BlockSense, to replace the traditional triangular architecture of MCS models by a decentralized paradigm. To achieve the goal of trustworthiness of BlockSense, we present a novel consensus protocol, namely Proof-of-Data (PoD), which leverages miners to conduct useful data quality validation work instead of “useless” hash calculation. Meanwhile, in order to preserve the privacy of the sensory data, we design a homomorphic data perturbation scheme, through which miners can verify data quality without knowing the contents of the data. We have implemented a prototype of BlockSense and conducted case studies on campus, collecting over 7,000 data from workers' mobile phones. Both simulations and real-world experiments show that BlockSense can not only improve system security, preserve data privacy and guarantee incentives fairness, but also achieve at least 5.6x faster than Ethereum smart contracts in verification efficiency.

Combination with the Simultaneous Wireless Information and Power Transfer (SWIPT) technology is expected as a promising solution to the issue of energy constraint in Wireless Sensor Networks (WSN). However, little attention is paid to the energy sustainability in SWIPT-enabled WSN with limited Mobile Energy Access Point (MEAP) configurations. To this end, a novel Energy-sustainable approach for SWIPT-enabled WSN with Constraint MEAP (ESWCM) configurations is proposed in this paper. To be specific, an Optimal Ring Width Determination (ORWD) algorithm is proposed, with the aim to ensure all the sensor nodes lie in the energy coverage of limited MEAPs from the perspective of the entire network. Subsequently, a GA-based Clustering algorithm constrained by cluster Head (GCH) connectivity is presented to promote the survivability of Cluster Heads (CHs) and the effectiveness of data transmission through reasonable cluster size. Additionally, the optimal parameters of each sensor node are determined through an Energy-efficient Parameter Optimization (EPO) algorithm to achieve energy sustainability of each individual sensor node. Experimental results indicate that ESWCM exhibits higher node survival rate by 124.7%, 2%, 29.9%, and 40.5% compared with LEACH, S-LEACH, R-LEACH, and DEEC after 1200 iterations respectively. Moreover, it also shows a survival rate of 100% after adjustments.

The emergence of the Simultaneous Wireless Information and Power Transfer (SWIPT) technology makes it possible to achieve energy sustainability in the Wireless Sensor Networks (WSNs). However, little attention was paid to the large-scale SWIPT-enabled WSNs. To this end, we synthesize the network Energy Efficiency (EE), energy sustainability conditions, and network throughput in the large-scale SWIPT-enabled WSNs, and propose a Topology-Scale-Adaptive and Energy Efficient Clustering Scheme (TSA-EECS). To be specific, the EE maximization problem is formulated as a fractional programming problem, which jointly optimizes the transmission power and the power splitting ratio of sensors. Subsequently, a Dinkelbach-based iterative algorithm is proposed to transform the problem and a Lagrangian function is presented to obtain a near-optimal solution through the gradient descent method. In addition, a BFOA-based Cluster Head (CH) selection algorithm is proposed to adapt to the large-scale network and reduce energy consumption for CH selection. Finally, extensive simulations are conducted to evaluate the effectiveness of TSA-EECS. Experimental results demonstrate that the proposed iterative algorithm converges after 15 iterations on average. In addition, compared with recent energy harvesting schemes, the network throughput of TSA-EECS is improved by 3–8%.

In the last decade, MIMO spatial multiplexing and distributed beamforming play a significant role in improving data throughput through cooperative transmission. It has been widely used in wireless communication, especially in 6G. However, the distributed uplink beamforming is still an open problem in highly dynamic environments. However, the proposed 6G technology represents the further integration of deep learning and wireless communication. In this article, we propose Argute Distributed Uplink Beamforming (ArguteDUB), which uses a feedback algorithm with an offline-trained deep learning model to implement highly dynamic distributed uplink beamforming for the Internet of Vehicles (IoV) in 6G. Specifically, each vehicle enables the base station (BS)/access point (AP) to separate different channel state information (CSI) by inserting orthogonal sequences into the sending data. The BS adopts deep learning to filter the noise and predict the beamforming weight to achieve phase synchronization. Unlike traditional distributed uplink beamforming, ArguteDUB can be adapted to the highly dynamic time-varying channels. The simple network structure ensures the fast response of ArguteDUB. In addition, we make ArguteDUB Orthogonal Frequency Division Multiplexing (OFDM) compatible so that it can be easily deployed in 6G networks. Our evaluation shows that ArguteDUB has an signal-to-noise ratio (SNR) gain of about 5 dB to 5.3 dB over the single vehicle transmission mode.

Snapshot compressive imaging (SCI) cameras compress high-speed videos or hyperspectral images into measurement frames. However, decoding the data frames from measurement frames is compute-intensive. Existing state-of-the-art decoding algorithms suffer from low decoding quality or heavy running time or both, which are not practical for real-time applications. In this article, we exploit the powerful learning ability of deep neural networks (DNN) and propose a novel tensor fast iterative shrinkage-thresholding algorithm net (Tensor FISTA-Net) as a real-time decoder for SCI cameras. Since SCI cameras have an accurate physical model, we can trade training time for the decoding time by generating abundant synthetic data and training a decoder on the cloud. Tensor FISTA-Net not only learns a sparse representation of the frames through convolution layers but also reduces the decoding time and memory consumption significantly through tensor operations, which makes Tensor FISTA-Net an appropriate approach for a real-time decoder. Our proposed Tensor FISTA-Net obtains an average PSNR improvement of 0.79-2.84 dB (video images) and 2.61-4.43 dB (hyperspectral images) over the state-of-the-art algorithms, along with more clear and detailed visual results on real SCI datasets, Hammer and Wheel, respectively. Our Tensor FISTA-Net reaches 45 frames per second in video datasets and 70 frames per second in hyperspectral datasets, meeting the real-time requirement. Besides, the trained model occupies only a 12 -MB memory footprint, making it applicable to real-time Internet of Things (IoT) applications.

Flow monitoring is widely applied in software-defined networks (SDNs) for monitoring network performance. Especially, detecting heavy hitters can prevent the Distributed Denial of Service (DDoS) attack. However, many existing approaches fall into one of two undesirable extremes: (i) inefficient collection where only accuracy is concerned in the method; (ii) sacrifice of accuracy due to fast detection. One practical problem with this is that it does not have the flexibility to adjust the monitoring strategy to the monitoring needs, making it difficult to meet different applications. To alleviate this problem, we propose our design of a novel flow monitoring framework that keeps the balance between accuracy and efficiency. It provides customized monitoring services for applications, where network resources can be saved, and the error rate can also be confined. In this paper, we present cReFeR, a three-step “compression Report-Feedback-Report” framework to monitor SDNs. The IP and the value compressor are specially designed to reduce the volume of flow statistics collection. This framework thus can achieve accuracy-ensured and resource-saving flow monitoring in SDNs. Theoretical analysis and simulated evaluation have proved the effectiveness of our solution. cReFeR keeps the error rate under 3% and reduces the amount of monitoring data more than 40%, which guarantees high efficiency compared with existing methods.

Consistent routing updates through Software-Defined Networking (SDN) can be difficult due to the asynchronous and distributed nature of the data plane. Recent studies have achieved consistent unicast routing updates. However, achieving consistent updates with drop-freeness and duplicate-freeness remains a challenge for multicast with fewer known results. This paper proposes a Novel Ordered Update Scheme called Nous, a novel approach that offers a comprehensive solution for consistently updating multicast routing based on SDN. To avoid duplicate entries, Nous configures the inport match field in the forwarding rules. Nous implements a dependency graph to schedule update operations dynamically. It also solves the Replace Operation Tree Migration Problem (ROTMP) using a greedy solution. To compare the greedy solution with the optimal solution, we employ the state-of-the-art mathematical programming solver Gurobi Optimizer 7.5 (for solving the optimization problem), Mininet 2.0, and Floodlight 1.2 (for simulation and comparison) to obtain a near-optimal solution. Simulation results show that using the greedy solution, Nous can usually achieve near-optimal solutions to the ROTMP with an average of fewer than 1.2 rounds and within 10 ms in different scenarios. This makes Nous the first ordered update scheme to guarantee two consistent states simultaneously.

Cloud services have shifted from monolithic designs to microservices running on cloud-native infrastructure with monitoring systems to ensure service level agreements (SLAs). However, traditional monitoring systems no longer meet the demands of cloud-native monitoring. In Alibaba’s “double eleven” shopping festival, it is observed that the monitor occupies resources of the monitored infrastructure and even disrupts services. In this paper, we propose a novel monitoring system named for cloud-native monitoring. achieves zero overhead in collecting raw metrics using one-sided remote direct memory access (RDMA) and remedies network congestion by adopting a receiver-driven flow control scheme. also features a priority queue mechanism to meet different quality of service requirements and an efficient batch processing design to relieve CPU occupation. has been deployed and evaluated in four different clusters with heterogeneous RDMA NIC devices and architectures in Alibaba Cloud. Results show that achieves no CPU occupation at the monitored host and supports$1\sim10k$hosts with$0.1\sim1s$sampling interval using a single thread for network I/O. significantly relieves the incast issue and maintains$80\sim95\%$of bandwidth utilization in several clusters when monitoring$1k$hosts. also ensures services with high priority accomplish collecting metrics earlier than low priority ones by at least$400 \mu s$when monitoring$1k$hosts.

Internet of Vehicles (IoV) has become an indispensable technology to bridge vehicles, persons, and infrastructures and is promising to make our cities smarter and more connected. It enables vehicles to exchange vehicular data (e.g., GPS, sensors, and brakes) with different entities nearby. However, sharing these vehicular data over the air raises concerns about identity privacy leakage. Besides, the centralized architecture adopted in existing IoV systems is fragile to single point-of-failure and malicious attacks. With the emergence of blockchain technology, there is the chance to solve these problems due to its features of being tamper-proof, traceability, and decentralization. In this article, we propose a privacy-preserving vehicular data sharing framework based on blockchain. In particular, we design an anonymous and auditable data sharing scheme using Zero-Knowledge Proof (ZKP) technology so as to protect the identity privacy of vehicles while preserving the vehicular data auditability for Trusted Authorities (TAs). In response to high mobility of vehicles, we design an efficient multi-sharding protocol to decrease blockchain communication costs without compromising the blockchain security. We implement a prototype of our framework and conduct extensive experiments and simulations on it. Evaluation and analysis results indicate that our framework can not only strengthen system security and data privacy but also reduce communication complexity by \(O(\frac{n\sqrt {m}}{m^2})\) times compared to existing sharding protocols.

In this paper, we show that by capturing the causal relationship among the computation of routers, one can transform the distributed program composed of routing processes into a sequential program, which allows the use of various sequential program analysis theories and tools for diagnosing and repairing routing configuration errors. This insight sheds light on future research on automatic network configuration diagnosis and repair. To demonstrate its feasibility and generality, we give the preliminary design of two methods for routing configuration error diagnosis: (1) data flow analysis using minimal unsatisfiable core and error invariants; and (2) control flow analysis using selective symbolic execution. Using real-world topologies and synthetic configurations, we show that both methods can effectively find errors in routing configurations while incurring reasonable overhead.

While learning to rank (LTR) is widely employed in web searches to prioritize pertinent webpages from the retrieved contents based on input queries, traditional LTR models stumble over two principal stumbling blocks leading to subpar performance: 1) the lack of well-annotated query-webpage pairs with ranking scores to cover search queries of various popularity, debilitating their coverage of search queries across the popularity spectrum, and 2) ill-trained models that are incapable of inducing generalized representations for LTR, culminating in overfitting. To tackle the above challenges, we proposed a Generative Semi-Supervised Pre-trained (GS2P) Learning to Rank model. Specifically, GS2P first generates pseudo-labels for the unlabeled samples using tree-based LTR models after a series of co-training procedures, then learns the representations of query-webpage pairs with self-attentive transformers via both discriminative (LTR) and generative (denoising autoencoding for reconstruction) losses. Finally, GS2P boosts the performance of LTR through incorporating Random Fourier Features to over-parameterize the models into “interpolating regime”, so as to enjoy the further descent of generalization errors with learned representations. We conduct extensive offline experiments on a publicly available dataset and a real-world dataset collected from a large-scale search engine. The results show that GS2P can achieve the best performance on both datasets, compared to baselines. We also deploy GS2P at a large-scale web search engine with realistic traffic, where we can still observe significant improvement in real-world applications. GS2P performs consistently in both online and offline experiments.

Wireless train communication network (WLTCN) is a promising technology for intelligent rail vehicles. It is responsible for bearer of train control services (TCS) and passenger information services (PIS), with the latter mainly referring to multimedia services. The two services have notably different quality of service (QoS) requirements from traditional telecommunication services. To realize multiple services co-existence bearer with different quality of service (QoS) requirements in a single network, we propose a radio access network (RAN) slicing framework to fully utilize the bandwidth resource within a WLTCN in this paper. Based on the characteristics of TCS and PIS, the communications models for the two services are proposed. Next, the slicing strategy problem is formulated as the system bandwidth minimization problem, and then it is transformed into an equivalent problem as the non-convexity. We proposed a dual-decomposition based bandwidth allocation (DBA) algorithm to derive the closed-form expressions for the optimal resource allocation. Simulation results show that the proposed slicing strategy enables WLTCN to meet the QoS requirements for TCS and PIS with minimal bandwidth consumption.

Satellite internet (Sat-Net) enables high-speed con-nectivity with low latency and extensive coverage. However, it faces challenges related to data security and reliable networking. Blockchain technology, with its decentralized and tamper-proof nature, offers a promising solution to these challenges. However, applying blockchain to the Sat-Net topology is difficult due to its highly dynamic structure, which results in restricted communication periods between satellites and ground stations. To address these issues and adapt to the Sat-Net topology, we propose a solution called RelSharding, which utilizes relayer satellites to relieve concurrent transmission pressure of ground stations by collecting and transmitting data transactions from client satellites. Through caching block headers and Merkle trees in relayer satellites, RelSharding can also reduce authentication latency between satellites utilizing simplified payment verification (SPV). Conducted on the modified SimBlock framework, our experiments indicate that RelSharding can enhance throughput up to 45x and decrease latency by 292x compared to existing blockchain solutions.

As one of the key technologies in the Internet of Things (IoT), Zigbee is widely used in industrial, agricultural, or medical scenarios due to its short distance, low delay, and high reliability of communications. However, the intensive deployment and concurrent transmissions of devices in ZigBee networks lead to severe collision and interference, reducing the throughput of the entire wireless network. Effective collision resolutions have been explored in the literature, but most of them use chip sequence as unit to decompose collision through waveform comparison and subtraction, which will cause issues such as error propagation, bit errors due to scarce samples, and high computational complexity. To make up for the above deficiencies, we propose a new physical layer design called OrthZig to achieve high-precision collision resolution in ZigBee networks without central controller. The key idea of OrthZig is to utilize the Direct Sequence Spread Spectrum adopted by ZigBee physical layer to achieve concurrent transmissions of multiple users based on the orthogonality of signal waveforms and distributed coordination. Additionally, we reduce the requirement for synchronization accuracy by partitioning the sync pair in the spread sequence, ensuring orthogonality for correct decoding. Extensive simulations are conducted from multiple dimensions to simulate the overall performance. Evaluation results demonstrate that OrthZig has lower average bit error rate and higher network throughput than the state-of-the-art.

Reproducing research results is important for the networking community. The current best practice typically resorts to: (1) looking for publicly available prototypes; (2) contacting the authors to get a private prototype; or (3) manually implementing a prototype following the description of the publication. However, most published network research does not have public prototypes and private ones are hard to get. As such, most reproducing efforts are spent on manual implementation based on the publications, which is both time and labor consuming and error-prone. In this paper, we boldly propose reproducing network research results using the emerging large language models (LLMs). We first prove its feasibility with a small-scale experiment, in which four students with essential networking knowledge each reproduces a different networking system published in prominent conferences and journals by prompt engineering ChatGPT. We report our observations and lessons and discuss future open research questions of this proposal.

Transformer has recently gained considerable popularity in low-level vision tasks, including image super-resolution (SR). These networks utilize self-attention along different dimensions, spatial or channel, and achieve impressive performance. This inspires us to combine the two dimensions in Transformer for a more powerful representation capability. Based on the above idea, we propose a novel Transformer model, Dual Aggregation Transformer (DAT), for image SR. Our DAT aggregates features across spatial and channel dimensions, in the inter-block and intra-block dual manner. Specifically, we alternately apply spatial and channel self-attention in consecutive Transformer blocks. The alternate strategy enables DAT to capture the global context and realize inter-block feature aggregation. Furthermore, we propose the adaptive interaction module (AIM) and the spatial-gate feed-forward network (SGFN) to achieve intra-block feature aggregation. AIM complements two self-attention mechanisms from corresponding dimensions. Meanwhile, SGFN introduces additional non-linear spatial information in the feed-forward network. Extensive experiments show that our DAT surpasses current methods. Code and models are obtainable at https://github.com/zhengchen1999/DAT.

Training images with data transformations, e.g., crops, shifts, rotations and color distortions, have been suggested as contrastive examples to evaluate the robustness of deep neural networks against data noises [1]. In this work, we propose a practical framework ContRE (which is the meaning of “against” in French) that uses Contrastive examples for DNN Robustness Estimation. Specifically, ContRE follows the assumption in [2], [3] that robust DNN models with good generalization performance are capable of extracting a consistent set of features and making consistent predictions from the same image under varying data transformations. Incorporating with a set of randomized strategies for well-designed data transformations over the training set, ContREadopts classification errors and Fisher ratios on the generated contrastive examples to assess and analyze the robustness of DNN models, which correlates to the models’ generalization performance. To show the effectiveness and efficiency of ContRE, extensive experiments have been done using various DNN models, e.g., ResNet, VGGNet, DenseNet, EfficientNet, etc., on three open source benchmark datasets, i.e., CIFAR-10, CIFAR-100, and ImageNet, with thorough ablation studies and applicability analyses. Our experiment results confirm that ❨1❩ behaviors of deep models on contrastive examples are strongly correlated to what on the testing set, and ❨2❩ the robustness that ContRE calculates is a robust measure of generalization performance complementing to the testing set in various settings. Codes is to be publicly available.

Both Transformer and Graph Neural Networks (GNNs) have been used in learning to rank (LTR), they however adhere to two distinct-yet-complementary problem formulations, i.e., ranking score regression based on query-webpage pairs and link prediction within query-webpage bipartite graphs, respectively. Though it is possible to pre-train GNNs or Transformers on source datasets and fine-tune them subject to sparsely annotated LTR datasets separately, the source-target distribution shifts across the pairs and bipartite graphs domains make it extremely difficult to integrate these diverse models into a single LTR framework at a web-scale. We introduce the novel MPGraf model, which utilizes a modular and capsule-based pre-training approach, aiming to incorporate regression capacities from Transformers and link prediction capabilities of GNNs cohesively. Specifically, rather than simply combining these two modules in stacking or parallelizing architectures, MPGraf proposes a three-step method to (1) construct query-webpage graphs from sparsely annotated query-webpage pairs, (2) pre-train the Transformer and GNN modules using source datasets from two domains, and (3) “surgically” fine-tune the integrated models with pretrained weights while handling the distribution shifts of two domains. Extensive experiments have been done to evaluate the performance of MPGraf using real-world datasets collected from large-scale search engines. The results show that MPGraf can outperform baseline algorithms on several major metrics. Further, we deploy and evaluate MPGraf atop a large-scale search engine with realistic web traffics via A/B tests, where we can still observe significant improvement. MPGraf performs consistently in both offline and online evaluations.

Root cause analysis for multi-dimensional time series from large scale micro-service scenarios aims at identifying the set of anomaly attributes by monitoring operational metrics. The online metrics provide a general indication to investigate these attributes' inter-dependencies and can guide the overall exploration process. However, the problem space for the root cause localization still remains largely challenging due to the combinatorial explosion of possible attribute combinations. This leads researchers and practitioners to (a) assume some prior distributions on the data set; (b) assume some data patterns on the attribute combinations; (c) perform pruning techniques to reduce the search space. Furthermore, state-of-the-art root cause analysis methods are often tied to one or more of these assumptions, which makes it difficult to be robust to general scenarios. In this paper, we conclude the heterogeneity in the data patterns by analyzing several open and industrial datasets. A uniform analytical framework, PatternRCA, is proposed such that it can be aware of the patterns in the metrics while avoiding explicit assumptions about them. We design an offline learning procedure that enables the framework to detect existing data patterns, which then can guide it to do fine-grain exploration in online metrics. Our extensive evaluation results show that PatternRCA outperforms state-of-the-art models with better benchmark results in public datasets. Meanwhile, it can scale to complex root cause analysis tasks on datasets with hybrid patterns in production environments.

All existing coflow scheduling algorithms compute dynamic-rate schedules that change the rates of flows during transmission. In this paper, we make a crucial finding: although dynamically adjusting the rates of flows could lead to a better coflow completion time (CCT) in theory, it would introduce additional pressures on the congestion control mechanism in the underlying network, which result in poor CCT in practice. This difference between theoretical CCT and practical CCT is further exacerbated in wide-area networks, where the topology does not provide any bisection guarantee as data center networks do. To this end, we designed a fixed-rate coflow scheduling policy called FSCO. Although in theory, the best fixed-rate schedule is usually suboptimal, it keeps the in-flight traffic relatively steady, reducing the risk of triggering congestion control. The core of FSCO is an efficient scheduling algorithm based on the classic network utilization maximization (NUM) framework. We implement a prototype of FSCO and evaluate its performance extensively using real-world topologies and coflow traces. Experimental results show that the total CCT reduces up to 30% compared to baselines while yielding up to 12× speedups compared to the solver.

Low-power wide-area networks (LPWAN) evolve rapidly with advanced communication primitives (e.g., coding, modulation) being continuously invented. This rapid iteration on LPWAN, however, forms a communication barrier between legacy wireless sensor nodes deployed years ago (e.g., ZigBee-based sensor node) with their latest competitor running a different communication protocol (e.g., LoRa-based IoT node): they work on the same frequency band but share different MAC- and PHY-layer regulations and thus cannot talk to each other directly. To break this barrier, we propose LigBee, a cross-technology communication (CTC) solution that enables symbol-level communication from the latest LPWAN LoRa node to legacy ZIGBEE node. We have implemented LigBee on both software-defined radios and commercial-off-the-shelf (COTS) LoRa and ZigBee nodes, and demonstrated that LigBee builds a reliable CTC link from LoRa node to ZigBee node on both platforms. Our experimental results show that i) LigBee achieves a bit error rate (BER) in the order of 10−3with 70 ∼ 80% frame reception ratio (FRR), ii) the range of LigBee link is over 300m, which is 6 ∼ 7.5× the typical range of legacy ZigBee and state-of-the-art solution, and iii) the throughput of LigBee link is maintained on the order of kbps, which is close to the LoRa’s throughput.

There has been a growing interest in applying machine learning to real-world tasks. However, due to the blackbox nature of machine learning models, it is crucial to (1) verify important properties of a model and (2) understand the reasons behind a model's prediction before deploying them in a production environment. Existing approaches typically handle them as two separate and sometimes orthogonal topics. In this paper, we show that the verification and interpretability of machine learning models are tightly related and can be unified by satisfiability modulo theories (SMT). Our key insight is: not only a wide range of properties of machine learning models can be formulated as SMT problems and verified accordingly, but many commonly studied interpretability questions can also be answered by iteratively checking the satisfiability and related properties of multiple SMT problems. Leveraging this insight, we design UINT, a general verification and interpretability framework for learning-based networking systems. UINT (1) allows operators to specify verification and interpretability problems as SMT formulas, (2) encodes the target machine learning models into SMT constraints, and (3) automatically solves the corresponding verification and interpretability problems using commodity SMT solvers. We implement a prototype of UINT and evaluate it on real-world learning-based networking systems. Results demonstrate the efficiency and efficacy of UINT in verifying and interpreting key questions for these systems.

While Learning to Rank (LTR) models on top of transformers have been widely adopted to achieve decent performance, it is still challenging to train the model with sufficient data as only an extremely small number of query-webpage pairs could be annotated versus trillions of webpages available online and billions of web search queries everyday. In the meanwhile, industry research communities have released a number of open-source LTR datasets with well annotations but incorporating different designs of LTR features/labels (i.e., heterogeneous domains). In this work, inspired by the recent progress in pre-training transformers for performance advantages, we study the problem of pre-training LTR models using both labeled and unlabeled samples, especially we focus on the use of well-annotated samples in heterogeneous open-source LTR datasets to boost the performance of pre-training. Hereby, we propose S2phere-Semi-Supervised Pre-training with Heterogeneous LTR data strategies for LTR models using both unlabeled and labeled query-webpage pairs across heterogeneous LTR datasets. S2phere consists of a three-step approach: (1) Semi-supervised Feature Extraction Pre-training via Perturbed Contrastive Loss, (2) Cross-domain Ranker Pre-training over Heterogeneous LTR Datasets and (3) End-to-end LTR Fine-tuning via Modular Network Composition. Specifically, given an LTR model composed of a backbone (the feature extractor), a neck (the module to reason the orders) and a head (the predictor of ranking scores), S2phere uses unlabeled/labeled data from the search engine to pre-train the backbone in Step (1) via semi-supervised learning; then Step (2) incorporates multiple open-source heterogeneous LTR datasets to improve pre-training of the neck module as shared parameters of cross-domain learning; and finally, S2phere in Step (3) composes the backbone and neck with a randomly-initialized head into a whole LTR model and fine-tunes the model using search engine data with various learning strategies. Extensive experiments have been done with both offline experiments and online A/B Test on top of Baidu search engine. The comparisons against numbers of baseline algorithms confirmed the advantages of S2phere in producing high-performance LTR models for web-scale search.

IoT uplink performance is crucial for a wide variety of IoT applications such as health sensing and industrial control, which demand reliable delivery of sensor data to the cloud. However, due to the limited transmission power budget imposed on many power-constrained IoT devices, IoT uplinks are highly susceptible to cross-technology interference (CTI) caused by coexisting networks. Previous approaches to mitigating CTI have relied on MAC/PHY designs. They suffer from poor performance and limited generality in the presence of wideband CTI sources such as Wi-Fi and RF jammer, which transmit aggressively on large spectrum chunks using diverse radio technologies.

Many activation values of Convolutional Neural Networks (CNNs) are zeros due to ReLU (Rectified Linear Unit), one of the most common activation functions used in modern neural networks. Since ReLU outputs are zero for all negative inputs, existing CNN acceleration approaches estimate zero outputs to skip redundant computation, which has to sacrifice accuracy for efficiency and leads to dilemma trade-offs and cockamamie configuration. In this paper, we introduce a lossless acceleration method ConvReLU++ for CNN inference on mobile devices, which accurately detects and skips zero-outputs for speedup without failures. The key to early negative detection is adopting reference-based upper-bounds calculation. This ensures that as soon as the intermediate results become negative, the final results are guaranteed to be negative. Upon detection, the remaining computation can be skipped and the following ReLU output can be simply set to zero. We rigorously prove the losslessness property of ConvReLU++, analyze the theoretical FLOPs reduction, and show the compatibility of our method with vector-level parallelism on mobile platforms. We implement ConvReLU++ in popular mobile inference frameworks and evaluate it on common deep vision tasks. The results demonstrate that ConvReLU++ can achieve 2.90% to 8.91% latency reduction over the original inference framework on edge devices without sacrificing accuracy. Our code can be found at https://github.com/monster119120/conv_relu_plus_plus.

Recent years have witnessed the emerging market of 3D facial reconstruction that supports numerous face-driven scenarios including modeling in virtual reality (VR), human-computer interaction, and affective computing applications. Current mainstream approaches rely on vision for 3D facial reconstruction, which may encounter privacy concerns and suffer from obstruction scenes and bad lighting conditions. In this paper, we present a nonintrusive 3D facial reconstruction system, mm3DFace, which leverages a millimeter wave (mmWave) radar to reconstruct 3D human faces that continuously express facial expressions in a privacy-preserving and passive manner. Based on the pre-processed mmWave signals, mm3DFace first extracts facial geometric features that capture subtle changes in facial expressions through a ConvNeXt model with triple loss embedding. Then, mm3DFace derives distance and orientation-robust facial shapes with 68 facial landmarks using region-divided affine transformation. mm3DFace next reconstructs facial expressions through a designed regional amplification method and finally generates 3D facial avatars that continuously express facial expressions. Extensive experiments involving 15 participants in real-world environments show that mm3DFace can accurately track 68 facial landmarks with 3.94% normalized mean error, 2.30mm mean absolute error, and 4.10mm 3D-mean absolute error, which is effective and practical in real-world 3D facial reconstruction.

IoT devices are enabled to capture and upload videos with increasing bitrates. Massive IIoT is eager for effective video processing techniques to satisfy the requirements of real-time video services. With the emergence of 5G-unlicensed (5G-U), ultra-low latency video applications become possible. However, existing encoding standards for video services in Web 2.0, such as H.265, are not naturally designed for IIoT video streaming, leading to bandwidth pressure where 5G-U coexists with various other wireless signals. To tackle this problem and to support low-latency video utilization by IIoT video sources, we propose an Adaptive Compression-Reconstruction framework named ACORN, which is based on compressed sensing and recent advances in deep learning. At end nodes, we compress multiple sequential video frames into a single frame to reduce video volume. We design a QoE-aware parameter selection mechanism to deal with volatile network environments during compression. With learnable gated convolution layers and channel-wise soft-thresholding operators, ACORN also builds a real-time reconstruction module. Experimental results reveal that video analytics can be conducted on compressed frames. The reconstruction algorithm in ACORN is with $1-4 \mathrm{~dB}$ improvements. Moreover, both the encoding time cost and the encoded video volume are reduced by more than $4 \times$ under the ACORN framework.

Diffusion models (DMs) have recently been introduced in image deblurring and exhibited promising performance, particularly in terms of details reconstruction. However, the diffusion model requires a large number of inference iterations to recover the clean image from pure Gaussian noise, which consumes massive computational resources. Moreover, the distribution synthesized by the diffusion model is often misaligned with the target results, leading to restrictions in distortion-based metrics. To address the above issues, we propose the Hierarchical Integration Diffusion Model (HI-Diff), for realistic image deblurring. Specifically, we perform the DM in a highly compacted latent space to generate the prior feature for the deblurring process. The deblurring process is implemented by a regression-based method to obtain better distortion accuracy. Meanwhile, the highly compact latent space ensures the efficiency of the DM. Furthermore, we design the hierarchical integration module to fuse the prior into the regression-based model from multiple scales, enabling better generalization in complex blurry scenarios. Comprehensive experiments on synthetic and real-world blur datasets demonstrate that our HI-Diff outperforms state-of-the-art methods. Code and trained models are available at https://github.com/zhengchen1999/HI-Diff.

This paper presents EmoRI, a novel single-chip mmWave radar-based egomotion estimation approach that works in challenging scenarios where moving objects exist in radar's Field of View (FoV). Essentially, estimating a mobile platform's egomotion using an on-board mmWave radar requires inferring the relative motion between radar and the points of the stationary objects (PSOs) in the radar point cloud. However, in practice, there could be no PSOs because of the blockage of moving objects. Even if PSOs exist, precisely identifying them is still challenging due to (i) the large quantity of points generated by the moving objects, and (ii) the huge angle estimation errors of the conventional point cloud generation algorithm. We empower EmoRI to overcome the above challenges incurred by moving objects with three core techniques, which include (i) a hybrid FFT-MUSIC algorithm that improves the angle estimation accuracy of single-chip mmWave radar, (ii) a multiple stationary target consensus algorithm that precisely selects the PSOs from the radar point cloud, and (iii) a simultaneous fusion and calibration mechanism that introduces an IMU as the auxiliary sensor, meticulously calibrates IMU accelerations with radar measurements, and complimentarily fuses these two modalities to obtain the 6-DoF egomotion. Our extensive experiments validate that EmoRI pushes the limit of single-chip mmWave radar-based egomotion estimation with moving objects in radar's FoV by reducing the per-meter destination error from decimeter to centimeter level.

Centralized data plane verification (DPV) faces significant scalability issues in large networks (i.e., the verifier being a performance bottleneck and single point of failure and requiring a reliable management network). We tackle this scalability challenge by introducing Tulkun, a distributed, on-device DPV framework. Our key insight is that DPV can be transformed into a counting problem on a directed acyclic graph, which can be naturally decomposed into lightweight tasks executed at network devices, enabling fast data plane checking in networks of various scales and types. With this insight, Tulkun consists of (1) a declarative invariant specification language, (2) a planner that employs a novel data structure DPVNet to systematically decompose global verification into on-device counting tasks, (3) a distributed verification messaging (DVM) protocol that specifies how on-device verifiers efficiently communicate task results to jointly verify the invariants, and (4) a mechanism to verify invariant fault-tolerance with minimal involvement of the planner. Extensive experiments with real-world datasets (WAN/LAN/DC) show that Tulkun verifies a real, large DC in 41 seconds while others tools need minutes or up to tens of hours, and shows an up to 2355× speed up on 80% quantile of incremental verification with small overhead on commodity network devices.

With the interdisciplinary advances of mobile communication and edge computing, massive heterogeneous tasks are accessing wireless networks and competing for the edge-end computing and communication resources. Digital twin (DT), which establishes the digital models of physical objects for simulation, analysis and optimization, provides a promising method for network scheduling and management. This paper proposes a DT-driven edge-end collaborative scheduling algorithm for heterogeneous tasks and heterogeneous computing/communication resources. Specifically, multiple end devices (EDs) cooperate with each other to accomplish a complex job, where each ED can offload individual task to multiple edge servers (ESs) for parallel computing. By fully considering deadline requirements of heterogeneous tasks, maximum computing capabilities of ESs and EDs, computing resource estimation deviations of DT, maximum transmit powers of EDs and tolerable peak interference powers to coexisting EDs, we formulate a job completion time minimization problem to jointly optimize the edge-end task division, transmit power control, computing resource type matching and allocation. To solve this non-convex problem, we first reformulate it by multi-agent Markov decision process, where a compound reward leveraging latency reward and deadline reward according to the task criticality is designed. Then, we propose a multi-agent deep reinforcement learning-based scheduling algorithm, where Actor-Critic framework with estimation and target networks is designed for policy and value iterations. Meanwhile, a step-by-step ϵ-greedy algorithm is proposed to balance exploration and exploitation, avoiding local optimal trap. Through offline centralized training by DT and online distributed execution by EDs, we realize edge-end collaborative computing for heterogeneous tasks. Experimental results demonstrate that, comparing with typical benchmark algorithms, the proposed algorithm converges with the highest reward and achieves the smallest job completion time, where the deadlines of heterogeneous tasks can be well satisfied respectively.

Since 2002, hundreds of thousands of vessels have equipped the Automatic Identification System (AIS), which continuously broadcasts its identity and location information for vessel collision avoidance. To utilize these scattered AIS data for further analysis, there are multiple AIS data platforms collecting AIS data from vessels around the world through their satellites and land-based stations. Thus, users can obtain AIS data of vessels from these platforms without dedicated devices. However, existing platforms work in silos, and AIS data is distributed across different platforms, resulting in reduced data availability. In addition, AIS is vulnerable to jamming and spoofing attacks, which can undermine the authenticity of AIS data. In this paper, we propose AISChain, a secure and fast blockchain-based AIS data platform. AISChain adopts consortium blockchain, which only permits those authorized parties (i.e., AIS data providers) to participate in the consensus protocol, and is compatible with current commodity AIS hardware. Since the whole system is co-maintained by multiple authorized parties, AISChain can integrate AIS data resources in a secure way. For avoiding repeated recording of AIS data on the chain, we design the Dynamic Bloom Filter Tree (DBFT) to realize efficient duplication detection in the transaction verification phase. We also propose the dual signature scheme to clarify the AIS data ownership. Moreover, we leverage the geographical location-based blockchain sharding approach to further improve the scalability of AISChain. We implement a prototype of AISChain, and conduct extensive experiments to evaluate the performance of AISChain. Evaluation results show that the search time of DBFT is negligible (4.3 ms) with an extreme low error ratio (0.4%). Meanwhile, AISChain can achieve more than 730 tx/s throughput even when nodes scale to 36. To the best of our knowledge, AISChain is the first work to apply the blockchain technology to secure the AIS data platform.

Recent advances in traffic signal control have witnessed the success of reinforcement learning. However, most of these approaches have focused on vehicle traffic and lack consideration for pedestrians. This can be attributed in part to the fact that the existing underlying technologies are not yet practical to deploy in real-world environments. Vision technologies, for example, can easily be obscured from view in reality. The direction of movement and position of pedestrians is difficult to estimate accurately. The emergence of 6G localization and tracking services offer new opportunities. With this base service, we intend to improve the efficiency, safety, and scalability of multi-intersection traffic signal control with mixed traffic flows. This problem is challenging for its coordination, scalability, and access of new traffic. To solve these challenges, we propose PV-TSC, a distributed reinforcement learning motivated traffic signal control with pedestrian access. We analyze different behaviors of pedestrian traffic, and integrate pedestrian traffic with the proven traffic signal control scheme for vehicle traffic. Finally, we conduct simulation experiments to illustrate the superiority of PV-TSC against classic methods, and further analyze the effectiveness of PV-TSC design by exploring its variants.

Whilelearning to rank(LTR) has been widely used in web search to prioritize most relevant webpages among the retrieved contents subject to the input queries, the traditional LTR models fail to deliver decent performance due to two main reasons: 1) the lack of well-annotated query-webpage pairs with ranking scores to cover search queries of various popularity, and 2) ill-trained models based on a limited number of training samples with poor generalization performance. To improve the performance of LTR models, tremendous efforts have been done from above two aspects, such as enlarging training sets with pseudo-labels of ranking scores by self-training, or refining the features used for LTR through feature extraction and dimension reduction. Though LTR performance has been marginally increased, we still believe these methods could be further improved in the newly-fashioned “interpolating regime”. Specifically, instead of lowering the number of features used for LTR models, our work proposes to transform original data with random Fourier feature, so as to over-parameterize the downstream LTR models (e.g., GBRank or LightGBM) with features in ultra-high dimensionality and achieve superb generalization performance. Furthermore, rather than self-training with pseudo-labels produced by the same LTR model in a “self-tuned” fashion, the proposed method incorporates the diversity of prediction results between the listwise and pointwise LTR models while co-training both models with a cyclic labeling-prediction pipeline in a “ping-pong” manner. We deploy the proposedCo-trained andOver-parameterizedLTRsystemCOLTRat Baidu search and evaluateCOLTRwith a large number of baseline methods. The results show thatCOLTRcould achieve$\Delta NDCG_{4}$= 3.64%$\sim$4.92%, compared to baselines, under various ratios of labeled samples. We also conduct a 7-day A/B Test using the realistic web traffics of Baidu Search, where we can still observe significant performance improvement around$\Delta NDCG_{4}$= 0.17%$\sim$0.92% in real-world applications.COLTRperforms consistently both in online and offline experiments.

Due to the urgent emergence of computation-intensive intelligent applications on end devices, edge computing has been put forward as an extension of cloud computing, to satisfy the low-latency requirements of these applications. To process heterogenous computation tasks on an edge node, the corresponding services should be placed in advance, including installing softwares and caching databases/libraries. Considering the limited storage space and computation resources on the edge node, services should be elaborately selected and deployed on the edge node and its computation resources should be carefully allocated to placed services, according to the arrivals of computation workloads. The joint service placement and computation resource allocation problem is particularly complicated, in terms of considering the stochastic arrivals of tasks, the additional latency incurred by service migration, and the waiting time of unprocessed tasks. Benefiting from deep reinforcement learning, we propose a novel approach based on parameterized deep Q networks to make the joint service placement and computation resource allocation decisions, with the objective of minimizing the total latency of tasks in a long term. Extensive simulations are conducted to evaluate the convergence and performance achieved by our proposed approach.

As a low-power and low-cost wireless protocol, the promising ZigBee has been widely used in sensor networks and cyber-physical systems. Since ZigBee based networks usually adopt tree or cluster topology, the convergecast scenarios are common in which multiple transmitters send packets to one receiver, leading to the severe collision problem. The conventional ZigBee adopts carrier sense multiple access with collisions avoidance to avoid collisions, which introduces additional time/energy overhead. The state-of-the-art methods resolve collisions instead of avoidance, in which mZig decomposes a collision by the collision itself and reZig decodes a collision by comparing with reference waveforms. However, mZig falls into high decoding errors only exploiting the signal amplitudes while reZig incurs high computational complexity for waveform comparison. In this paper, we propose CmZig to embrace channel estimation in multiple-packet reception (MPR) of ZigBee, which effectively improves MPR via lightweight computing used for channel estimation and collision decomposition. First, CmZig enables accurate collision decomposition with low computational complexity, which uses the estimated channel parameters modeling both signal amplitudes and phases. Second, CmZig adopts reference waveform comparison only for collisions without chip-level time offsets, instead of the complex machine learning based method. We implement CmZig on USRP-N210 and establish a six-node testbed. Results show that CmZig achieves a bit error rate in the order of$10^{-3}$and more than 80% packet reception rate, which outperforms state-of-the-art mZig.

The automotive industry is increasingly deploying software solutions to provide value-added features for vehicles, especially in the era of vehicle electrification and automation. However, the ever-increasing cyber components of vehicles (i.e., computation, communication, and control) incur new risks of anomalies, as evident by the millions of vehicle recalls by different automakers. To mitigate these risks, we design theB-Diag, a battery-based diagnostic system detects engine anomalies with a cyber-physical approach. The core idea ofB-Diagis to diagnose engines using the physically-induced correlations between battery voltage and engine variables, which is captured as a customized 3-layer correlation graph and a set of data-driven norm models describing the edges thereof. The design ofB-Diagis steered by a dataset collected with a prototype system when driving a 2018 Subaru Crosstrek in real-life for over three months. Our evaluation showsB-Diagto detect anomalies of 17 engine variables with a$>$$86\%$(up to$100\%$) accuracy.

Vehicle localization service is a fundamental component of intelligent transportation systems. The widely used satellite navigation systems perform poorly in urban areas because the lines of sight to satellites are blocked by complex terrain characteristics, e.g., buildings, elevated streets and interchanges. In this paper, we design RadioLoc, a novel system achieving accurate, efficient, all-terrain vehicle localization with two key design points. First, RadioLoc harvests the frequency modulation (FM) signal, which has higher availability than satellite signal in complex terrains, as the signal source for localization. Second, RadioLoc integrates modern machine learning techniques into the processing of FM signals to efficiently learn the accurate vehicle localization in all-terrain environments. We validate the feasibility of FM-based vehicle localization and corresponding challenges and practical issues via field tests (e.g., signal distortion, signal inconsistency and limited in- vehicle radio bandwidth), and develop a series of advanced techniques in RadioLoc to address them, including adaptive batching, frequency sweeping, a novel multipath delay spread filter, a reconstructive PCA denoiser and a tailored FM feature extractor. We then develop a generic, modular localization module in RadioLoc, and design different learning-based 3D position identification algorithms for this module. We implement a prototype of RadioLoc and perform extensive field experiments to evaluate its efficiency and efficacy. Results show that (1) RadioLoc achieves a real-time localization latency of less than 100 milliseconds; (2) RadioLoc achieves a worst-case localization accuracy of 99.6% even in an underground parking lot, and (3) the horizontal error of RadioLoc is only one sixth of a dedicated GPS device even when the vehicle is moving at a high-speed (i.e., 80 km/h) in a complex highway scenario.

The exponential growth of Massive Open Online Courses (MOOCs) surges the needs of advanced models for personalized Online Education Services (OES). Existing solutions successfully recommend MOOCs courses via deep learning models, they however generate weak “course embeddings” with original profiles, which contain noisy and few enrolled courses. On the other hand, existing algorithms provide recommendation orders according to the score of each course while ignoring personalized demands of users. To tackle the above challenges, we propose aMetaHierarchicalReinforcedRankingapproachMHRR, which consists of a meta hierarchical reinforcement learning pre-trained mechanism and an over-parameterized ranking regressor to enhance the representation learning of courses and learners while refining the ranking result of recommended courses. Specifically,MHRRcombines a user profile reviser and a meta embedding generator to provide course embedding representation enhancement for recommender services. Furthermore,MHRRtransforms learned representations generated from recommender services with Gaussian kernel approximation to over-parameterize the downstream learning to rank (LTR) models with representations in ultra-high dimensionality. We deployMHRRon a real-world MOOCs platform and evaluate it with a large number of baseline models. The results show thatMHRRoutperforms baseline algorithms on two major metrics, including Hit Ratio (HR) and Normalized Discounted Cumulative Gain (NDCG). Also, we conduct a 7-day online evaluation using the realistic traffic of a large-scale real-world MOOCs platform, where we can still observe significant improvement in real-world applications.MHRRperforms consistently both in the online and offline evaluation.

The Low-Earth-Orbit (LEO) mega-constellation networks, by providing low-latency and high-speed communications, are becoming indispensable infrastructures for the future six-generation (6G) architecture. Consequently, the topology, with thousands of satellites equipped with batteries of limited life, has to be adaptively controlled with high energy efficiency. However, existing work lacks the joint consideration of energy efficiency and load adaptation. In this paper, we first propose the line-of-sight condition to determine the candidate ISL set. Next, we model the energy consumption of the LEO mega-constellation networks. Along this direction, we formulate the Load-Adaptive and Energy-Efficient (LAEE) topology control problem in LEO mega-constellation networks and prove its NP-hardness. Finally, we propose the Amortized Energy based Topology Control (AETC) algorithm to solve the LAEE problem, with good adaptation to the fluctuating load and guarantees connectivities between any two satellites. Extensive simulation results demonstrate that the AETC algorithm outperforms related schemes in terms of energy consumption and results in good topology stability.

A urine bag is a common medical appliance widely used in clinical treatment for patients with urinary frequency, urgency, or incontinence problems. The real-time monitoring and alarming of the liquid volume in the bag are necessary to avoid the infection caused by urine reflux. Current monitoring relies on manual observations of doctors and medical attendants, but it has problems with timeliness, especially in surgery or at night. In this paper, we propose Wi-Uro, a real-time, low-cost, and accurate urine bag monitoring and alarming system with commodity Wi-Fi devices. To solve the random deformation of urine bags possibly due to human postures, it integrates Wi-Fi Channel State Information (CSI) with tension sensor readings to infer liquid volume in bags. Once the volume is exceeding the threshold, Wi-Uro system will prompt the alarm information immediately. Evaluations based on real urine bags show a satisfactory estimation accuracy (over 95%), which means that Wi-Uro can be applied in routine patient care.

With the proliferation of laser communication and space networks, the increasing communication requests, tasks, and traffic loads introduce new challenges to data routing to laser space networks (LSNs). Existing routing strategies perform in a distributed manner on single-layer networks. But they suffer from the delay of information update in highly dynamic LSNs, which encounter unstable laser links and uneven traffic distribution problems. In this paper, we first propose a multi-layer LSN architecture. It is composed of a routing layer with high-orbit satellites for routing planning and a forwarding layer with low-orbit satellites for data transmitting. A centralized multi-layer optical routing strategy is further designed, namely CMOR. It is expected to provide the data forwarding plan depending on the global view of the routing layer on real-time laser link status and traffic loads of the forwarding layer. Compared with single-layer distributed routing, CMOR is proven to have a lower packet loss rate and transmission latency with large-scale satellite simulations.

With the fast evolution in the cellular communication, the unlicensed spectrum is exploited to resolve the shortage of band resources. The sharing of the unlicensed spectrum extends the applications of LTE and 5G NR techniques, especially in the industrial Internet of Things (IIoT). However, the coexistence problem among various communication technologies in the unlicensed spectrum arises great concerns due to the different communication mechanisms. The existing solutions are either not compatible with the LTE/NR standards or not flexible enough for complex and dynamic IIoT environments. In this paper, we propose a policy learning based unlicensed communication (PLUC) framework to directly learn coexistence policies from the spectrogram of frequency channels. A recurrent neural network (RNN) is built to deal with the observations from time-variant spectrogram and extract deep learning features. We further verify this framework under the duty cycle mechanism and the listen before talk mechanism in 3GPP standards, respectively. The experiments reveal the effectiveness of the proposed framework in the dynamic environment.

In the last decade, MIMO spatial multiplexing and distributed beamforming play a significant role in improving data throughput through cooperative transmission. It has been widely used in wireless communication, especially in 6G. However, the distributed uplink beamforming is still an open problem in highly dynamic environments. However, the proposed 6G technology represents the further integration of deep learning and wireless communication. In this paper, we propose Argute Distributed Uplink Beamforming (ArguteDUB), which uses a feedback algorithm with an offline-trained deep learning model to implement highly dynamic distributed uplink beamforming for the Internet of Vehicles (IoV) in 6G. Specifically, each vehicle enables the base station (BS)/access point (AP) to separate different channel state information (CSI) by inserting orthogonal sequences into the sending data. The BS adopts deep learning to filter the noise and predict the beamforming weight to achieve phase synchronization. Unlike traditional distributed uplink beamforming, ArguteDUB can be adapted to the highly dynamic time-varying channels. The simple network structure ensures the fast response of ArguteDUB. In addition, we make ArguteDUB Orthogonal Frequency Division Multiplexing (OFDM) compatible so that it can be easily deployed in 6G networks. Our evaluation shows that ArguteDUB has an SNR gain of about 5dB to 5.3dB over the single vehicle transmission mode.

In the field of various downstream tasks of graph learning, graph neural networks (GNNs) have achieved the state-of-the-art (SOTA) performance benefits from its special propagation mechanism. The propagation mechanism aggregates attributes from neighbor nodes to obtain expressive node representations, which is pivotal for achieving SOTA performance in various downstream tasks. However, in most graph datasets, the neighborhood of each node may contain weakly correlated neighbors (WCNs), whose attributes may impair the expressiveness of central node representations. Though efforts have been devoted to solving such problem, they merely focus on aggregating fewer or even subtracting the attributes of WCNs. However, WCNs still share some correlated information with the central node, thus the correlated information provided by WCNs is underutilized. In this work, we devote to leveraging the correlated information provided by WCNs with our proposed method, namely GNN-detective. This detective can efficiently and automatically distinguish WCNs, as well as dig out their correlated information in the graph. It is realized by a semi-supervised learning framework, where the Differential Propagation (DP) module is designed specially for information triage and utilization. This module can fully leverage the correlated information provided by WCNs, and eliminate interference of uncorrelated information. We have conducted semi-supervised node classification tasks on 9 benchmark datasets. Our proposed method is proven to achieve the best performance in processing WCNs. The problems such as over-smoothing and overfitting are also mitigated as evaluated.

With the development of smart indoor environments, user authentication becomes an essential mechanism to support various secure accesses. Although recent studies have shown initial success on authenticating users with human activities or gestures using WiFi, they rely on predefined body gestures and perform poorly when meeting undefined body gestures. This work aims to enable WiFi-based user authentication with undefined body gestures rather than only predefined body gestures, i.e., realizing a gesture-independent user authentication. In this paper, we first explore physiological characteristics underlying body gestures, and find that statistical distributions under WiFi signals induced by body gestures can exhibit invariant individual uniqueness unrelated to specific body gestures. Inspired by this observation, we propose a user authentication system, which utilizes WiFi signals to identify individuals in a gesture-independent manner. Specifically, we design an adversarial learning-based model, which suppresses specific gesture characteristics, and extracts invariant individual uniqueness unrelated to specific body gestures, to authenticate users in a gesture-independent manner. Extensive experiments in indoor environments show that the proposed system is feasible and effective in gesture-independent user authentication.

Nowadays, the market of 3D human posture tracking has extended to a broad range of application scenarios. As current mainstream solutions, vision-based posture tracking systems suffer from privacy leakage concerns and depend on lighting conditions. Towards more privacy-preserving and robust tracking manner, recent works have exploited commodity radio frequency signals to realize 3D human posture tracking. However, these studies cannot handle the case where multiple users are in the same space. In this paper, we present a mmWave-based multi-user 3D posture tracking system, m3Track, which leverages a single commercial off-the-shelf (COTS) mmWave radar to track multiple users' postures simultaneously as they move, walk, or sit. Based on the sensing signals from a mmWave radar in multi-user scenarios, m3Track first separates all the users on mmWave signals. Then, m3Track extracts shape and motion features of each user, and reconstructs 3D human posture for each user through a designed deep learning model. Furthermore. m3Track maps the reconstructed 3D postures of all users into 3D space, and tracks users' positions through a coordinate-corrected tracking method, realizing practical multi-user 3D posture tracking with a COTS mmWave radar. Experiments conducted in real-world multi-user scenarios validate the accuracy and robustness of m3Track on multi-user 3D posture tracking.

Recently, Transformer architecture has been introduced into image restoration to replace convolution neural network (CNN) with surprising results. Considering the high computational complexity of Transformer with global attention, some methods use the local square window to limit the scope of self-attention. However, these methods lack direct interaction among different windows, which limits the establishment of long-range dependencies. To address the above issue, we propose a new image restoration model, Cross Aggregation Transformer (CAT). The core of our CAT is the Rectangle-Window Self-Attention (Rwin-SA), which utilizes horizontal and vertical rectangle window attention in different heads parallelly to expand the attention area and aggregate the features cross different windows. We also introduce the Axial-Shift operation for different window interactions. Furthermore, we propose the Locality Complementary Module to complement the self-attention mechanism, which incorporates the inductive bias of CNN (e.g., translation invariance and locality) into Transformer, enabling global-local coupling. Extensive experiments demonstrate that our CAT outperforms recent state-of-the-art methods on several image restoration applications. The code and models are available at https://github.com/zhengchen1999/CAT.

Gait-based user authentication schemes have been widely explored because of their ability of non-invasive sensing and avoid replay attacks. However, existing gait-based user au-thentication methods are environment-dependent. In this paper, we present an environment-independent gait-based user authen-tication system, RFPass, which can identify different individuals leveraging RFID signals. Specifically, we find that Doppler shift of RF signals can describe environment-independent gait features for different individuals. In RFPass, when a user walks through the RFPass system, RF signals are first collected by a deployed RFID tag array. Then, RFPass removes environmental interfer-ence from the collected RF signals through a proposed Multipath Direction of arrival (DoA) Signal Select (MDSS) algorithm. Next, we construct an environment-independent gait profile to describe the user's walking movements. Afterward, environment-independent gait features are extracted by a proposed CNN-RNN model. Based on the extracted gait features, a trained model is constructed for user authentication and spoofer detection. Extensive experiments in different real environments demonstrate that RFPass can achieve environment-independent gait-based user authentication.

The Narrow Band-Internet of Things (NB-IoT) is a wireless protocol with low-power, low-cost, and wide coverage, which has a broad application prospect in fields like smart city or manufacturing. In order to expand the network coverage, the repetition mechanism is designed in NB-IoT, where the same information is required to be transmitted repeatedly for the accurate decoding of received signals in low signal-to-noise ratio (SNR) environments. However, such repetition mechanism will cause a dramatic decrease in the spectrum utilization, which will be greatly reduced by up to 1/128. Literature has explored efficient coding methods, such as Non-Orthogonal Multiple Access (NOMA), but they can only achieve 55% maximum improvement on spectral efficiency.To further increase the spectrum utilization, this paper propose a novel uplink repetition mechanism design for NB-IoT, namely mNB-IoT. It can enable multiple user equipments (UEs) to transmit data to base stations in parallel using the same subcarriers. Based on the timing synchronization of NB-IoT, the original repetition mechanism is changed to the repetition based on orthogonal sequences to realize concurrent transmission among multiple UEs. The repetition intervals and times are then unified among UEs to maximize spectral efficiency. Experiments built upon 3 USRP devices and simulations on 128 UEs have proven the efficiency of mNB-IoT in realizing the repetition mechanism without spectral efficiency reduction.

Abstract Energy inequality caused by the process of cluster head election has a large influence on energy efficiency and the network lifetime of wireless sensor networks (WSNs). To this end, a novel concept of EI ec is proposed to evaluate the equality degree of energy consumption. Related theorems for establishing the candidate set of cluster heads are proposed, with the aim of promoting energy equality in each cluster. Subsequently, a novel energy‐efficiency‐adaptive cluster formation mechanism based on economic (ECFE) theory is proposed and detailed. Finally, extensive experiments are carried out to assess its energy efficiency and the network performance by comparisons with the existing classic and latest intelligent clustering algorithms. The results indicate that ECFE improves not only the energy efficiency but also the network performance effectively.

Practical and accurate localization systems are important to mobile targets that enable promising services such as navigation and augmented reality. With the proliferation of WiFi, existing WiFi-based localization systems have leveraged RSSI, fingerprints, landmarks, time of arrival, or angle of arrival to locate targets, while no related work pays attention to mobile targets themselves. For wheel-driven mobile targets, such as vehicles, bikes, and wheeled robots, we design and implement WheelLoc, a novel WiFi-based localization system leveraging the rotation of wheels. The specially designed WheelLoc hardware is cost-effective and self-powered with the composition of three commercial antennas and a solar cell, which is also easy to be installed on wheels. A hybrid WheelLoc algorithm is further proposed to realize accurate localization in diverse environments, whether the wheel of targets is static or mobile, indoor or outdoor, on flat or bumpy ground. The movements of individual antennas are exploited to emulate linear, cycloid, and circular antenna arrays using a new formulation of Synthetic Aperture Radar (SAR). Extensive experiments are conducted on bikes in the real world. Performance results demonstrate that WheelLoc does not require any user interaction, yet achieves comparable accuracy with the state-of-the-art localization systems using WiFi.

This special issue of the IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING (T-ASE) focuses on how the state-of-the-art achievements and applications in the general area of artificial intelligence in automation for autonomous unmanned systems applications. As Guest Editors, we are very pleased to present the selected 16 articles, whose topics are specifically related to artificial intelligence real-time object detection, recognition, localization, control optimization, motion planning, formation control, adaptive control, and autonomous decision-making.

Indoor vehicle localization is an underlying technology for realizing Autonomous Valet Parking (AVP), which demands high accuracy and reliability. However, existing localization technologies, such as GPS, WiFi, Bluetooth, suffer from either low availability or high cost, which are not practical in the real world. In order to put AVP into practice, We desperately need an efficient and reliable indoor vehicle localization technology. In this paper, we propose aDeep learning andFM fingerprint map based indoor vehicleLocalization method, namely DeFLoc, which leverages FM signals to achieve accurate and practical indoor localization. In order to reduce the workload of the FM fingerprints collecting process, DeFLoc uses partially uniform sampling to decrease sample data volume and reconstructs the FM fingerprint map from collected incomplete fingerprints precisely using a dedicated deep Convolutional Neural Network (CNN). To alleviate the influence of signal distortions in some FM frequencies, we further design smooth layers in the neural network for improving the accuracy of map reconstruction. Moreover, we devise a continuous vehicle localization algorithm by considering the preferences of vehicle movements to assist us to calibrate localization. We implemented a prototype of DeFLoc and conducted extensive experiments both in simulation and practice. Evaluation results show that our proposed reconstruction model improves accuracy by 40% over conventional matrix completion methods even under the 60% data missing rate. With the precisely reconstructed fingerprint map, DeFLoc achieves over 90% localization accuracy, which indicates DeFLoc can realize accurate and practical indoor vehicle localization.

To build a secure wireless networking system, it is essential that the cryptographic key is known only to the two (or more) communicating parties. Existing key extraction schemes put the devices into physical proximity and utilize the common inherent randomness between the devices to agree on a secret key, but they often rely on specialized hardware (e.g., the specific wireless NIC model) and have low bit rates. In this article, we seek a key extraction approach that only leverages off-the-shelf mobile devices, while achieving significantly higher key generation efficiency. The core idea of our approach is to exploit the fast varying inaudible acoustic channel as the common random source for key generation and wireless parallel communication for exchanging reconciliation information to improve the key generation rate. We have carefully studied and validated the feasibility of our approach through both theoretical analysis and a variety of measurements. We implement our approach on different mobile devices and conduct extensive experiments in different real scenarios. The experiment results show that our approach achieves high efficiency and satisfactory robustness. Compared with state-of-the-art methods, our approach improves the key generation rate by 38.46% and reduces the bit mismatch ratio by 42.34%.

Convergecast is a fundamental operation in wireless sensor networks (WSNs). To support long-term deployment of WSNs, sensor nodes normally operate at low-duty-cycles. However, the low-duty-cycle operation significantly reduces the communication chance between nodes. Consequently, the risk of data collisions significantly increases when multiple senders transmit packets to a receiver during its very short active period. This problem further causes not only wasted packet retransmissions, but also a large delivery latency. Under such conditions, collision-free medium access is more appealing than recovering after collision for low-duty-cycle WSNs. In this work, we propose anincast-collision-free convergecast protocol, named iCore, to address the many-to-one collision problem in low-duty-cycle WSNs. iCore employs the dynamic forwarding technique, establishes a non-conflicting schedule for efficient convergecast, and improves the channel utilization by allowing senders to opportunistically transmit packets once detecting unused slots. Specifically, we design efficient forwarder assignment and forwarding optimization algorithms that ensure low end-to-end latency under diverse data traffic types. Through comprehensive performance evaluations, we demonstrate that, compared with the baseline protocol, iCore effectively minimizes the end-to-end delay by 25% ~ 57% and maintains high delivery ratio and energy efficiency for different many-to-one convergecast scenarios.

Internet of Vehicles (IoV) has become an indispensable technology to bridge vehicles, persons and infrastructures, and is promising to make our cities smarter and more connected. It enables vehicles to exchange vehicular data (e.g., GPS, sensors, and brakes) with different entities nearby. However, sharing these vehicular data over the air raises concerns about identity privacy leakage. Besides, the centralized architecture adopted in existing IoV systems is fragile to single point of failure and malicious attacks. With the emergence of blockchain technology, it has the chance to solve these problems due to its features of tamper-proof, traceability and decentralization. In this paper, we propose a privacy-preserving vehicular data sharing framework based on blockchain. In particular, we design an anonymous and auditable data sharing scheme using Zero-Knowledge Proof (ZKP) technol-ogy so as to protect the identity privacy of vehicles while preserving the vehicular data auditability for Trusted Authorities (TAs). In response to high mobility of vehicles, we design an efficient multi-sharding protocol to decrease blockchain communication costs without compromising the blockchain security. We implement a prototype of our framework and conduct extensive experiments and simulations on it. Evaluation and analysis results indicate that our framework can not only strengthen system security and data privacy, but also increase the data authenticity verification efficiency by 5x comparing to existing privacy-preserving schemes.

The booming of mobile technologies and Internet of Things (IoTs) have facilitated the explosion of wireless devices and brought convenience to people's daily lives. Coming with the explosive growth of wireless devices, incompatibility of heterogeneous wireless technologies hindered the growing demands for everything connected. And spectrum sharing among heterogeneous wireless technologies has led to severe Cross-Technology Interference (CTI), which is a vital obstacle for network reliability and spectrum utilization. Researches in recent years have shown that Cross-Technology Communication (CTC) turns out to be a promising solution with broad perspective for the coexistence of heterogeneous wireless technologies. However, due to the physical layer incompatibility of WiFi and Bluetooth Low Energy (BLE), the researches about CTC between these two most wildly used wireless technologies are limited by now. In this paper, we propose WiBWi, a payload encoding-based bidirectional CTC scheme between BLE and WiFi, which can achieve near-optimal throughput and powerful robustness. For uplink, i.e., BLE to WiFi communication, WiBWi leverages a novel extended WiFi preamble detection rule and probabilistic inference based encode mapping to achieve fast and reliable communication. For downlink, i.e., WiFi to BLE communication, WiBWi introduces an encoding mapping scheme in the sight of BLE receiver with little modification to accomplish high throughput and robustness. Extensive evaluation shows that WiBWi can offer near-optimal throughput (near the maximum throughput of BLE) and extremely low bit error rate (less than 1%).

Abstract Human–computer interaction through touch screens plays an increasingly important role in our daily lives. Besides smartphones and tablets, laptops are the most prevalent mobile devices for both work and leisure. To satisfy the requirements of some applications, it is desirable to re-equip a typical laptop with both handwriting and drawing capability. In this paper, we design a virtual writing tablet system, VPad, for traditional laptops without touch screens. VPad leverages two speakers and one microphone, which are available in most commodity laptops, to accurately track hand movements and recognize writing characters in the air without additional hardware. Specifically, VPad emits inaudible acoustic signals from two speakers in a laptop and then analyzes energy features and Doppler shifts of acoustic signals received by the microphone to track the trajectory of hand movements. Furthermore, we propose a state machine-based trajectory optimization method to correct the unexpected trajectory and employ a stroke direction sequence model based on probability estimation to recognize characters users write in the air. Experimental results show that VPad achieves the average error of 1.55 cm for trajectory tracking and the accuracy over 90% of character recognition merely through built-in audio devices on a laptop.

Abstract The unstable link quality in wireless sensor networks (WSNs) directly affects the success rate of data transmission. The retransmission mechanism is one of the commonly used methods to solve this problem. However, too many retransmissions could lower the communication efficiency. Therefore, to reduce retransmissions while guaranteeing the communication reliability in WSNs, this study introduces the NarrowBand Internet of Things (NB‐IoT) technology, and builds a network including both sensor and NB‐IoT nodes. The NB‐IoT node is designed to support both the radio frequency and the NarrowBand communication modes; thus it can communicate with both sensor nodes and NB‐IoT base stations. Further, the communication reliability metrics considering both the link quality and the number of retransmissions in different communication modes are defined, based on which, an adaptive communication reliability algorithm is proposed to switch the communication modes of nodes. The simulation results verify that the proposed algorithm can achieve higher success rate with less end‐to‐end delay and flexibly control the cost on NB‐IoT communication.

This paper demonstrates the feasibility of a side-channel attack to infer keystrokes on touch screen leveraging an off-the-shelf smartphone. Although there exist some studies on keystroke eavesdropping attacks on touch screen, they are mainly direct eavesdropping attacks, i.e., require the device of victims compromised to provide side-channel information for the adversary, which are hardly launched in practical scenarios. In this work, we show the practicability of an indirect eavesdropping attack, KeyListener, which infers keystrokes on QWERTY keyboards of touch screen leveraging audio devices on a smartphone. We investigate the attenuation of acoustic signals, and find that a user's keystroke fingers can be localized through the attenuation of acoustic signals received by the microphones in the smartphone. We then utilize the attenuation of acoustic signals to localize each keystroke, and further analyze errors induced by ambient noises. To improve the accuracy of keystroke localization, KeyListener further tracks finger movements during inputs through phase change and Doppler effect to reduce errors of acoustic signal attenuation-based keystroke localization. In addition, a binary tree-based search approach is employed to infer keystrokes in a context-aware manner. The proposed keystroke eavesdropping attack is robust to various environments without the assistance of additional infrastructures. Extensive experiments demonstrate that the accuracy of keystroke inference in top-5 candidates can approach 90 percent with a top-5 error rate of around 6 percent, which is a strong indication of the possible user privacy leakage of inputs on QWERTY keyboard.

As the Internet of Things thrives, monitors and cameras produce tons of image data every day. To efficiently process these images, many compressed imaging frameworks are proposed. A compressed imaging framework comprises two parts, image signal measurement and reconstruction. Although a plethora of measurement devices have been designed, the development of the reconstruction is relatively lagging behind. Nowadays, most of existing reconstruction algorithms in compressed imaging are optimization problem solvers based on specific priors. The computation burdens of these optimization algorithms are enormous and the solutions are usually local optimums. Meanwhile, it is inconvenient to deploy these algorithms on cloud, which hinders the popularization of compressed imaging. In this article, we dive deep into the random projection to build reconstruction algorithms for compressed imaging. We first fully utilize the information in the measurement procedure and propose a combinatorial sparse random projection (SRP) reconstruction algorithm. Then, we generalize the SRP to a novel distributed algorithm called Cloud-SRP (CSRP), which enables efficient reconstruction on cloud. Moreover, we explore the combination of SRP with conventional optimization reconstruction algorithms and propose the Iterative-SRP (ISRP), which converges to a guaranteed fixed point. With minor modifications on the naive optimization algorithms, the ISRP yields better reconstructions. Experiments on real ghost imaging reconstruction reveal that our algorithms are effective. And simulation experiments show their advantages over the classical algorithms.

Network resource reservation systems are being developed and deployed, driven by the demand and substantial benefits of providing performance predictability for modern distributed applications. However, existing systems suffer limitations: They either are inefficient in finding the optimal resource reservation, or cause private information (e.g., from the network infrastructure) to be exposed (e.g., to the user). In this paper, we design BoxOpt, a novel system that leverages efficient oracle construction techniques in optimization and learning theory to automatically, and swiftly learn the optimal resource reservations without exchanging any private information between the network and the user. In BoxOpt, we first model the simple reservation interface adopted in most reservation systems as a resource membership oracle. Second, we develop an efficient algorithm that constructs a resource separation oracle by a linear number of calls on resource membership oracle. Third, we develop a generic framework to construct a resource optimization oracle by iteratively calling the resource separation oracle, and then develop three novel, efficient algorithms under this generic framework, the best of which computes the optimal resource reservation by a linear number of calls on resource separation oracle. As such, BoxOpt can discover the optimal resource reservation with O(n2) calls on the resource membership oracle. We implement a prototype of BoxOpt with and demonstrate its efficiency and efficacy via extensive experiments using real network topology and a 7-day trace from a large operational federation network. Results show that (1) BoxOpt has a 100% correctness ratio by comparing with a state-of-the-art optimization solver, and (2) for 90% of requests, BoxOpt learns the optimal resource reservation within 10 seconds.

Snapshot compressive imaging (SCI) cameras capture high-speed videos by compressing multiple video frames into a measurement frame. However, reconstructing video frames from the compressed measurement frame is challenging. The existing state-of-the-art reconstruction algorithms suffer from low reconstruction quality or heavy time consumption, making them not suitable for real-time applications. In this paper, exploiting the powerful learning ability of deep neural networks (DNN), we propose a novel Tensor Fast Iterative Shrinkage-Thresholding Algorithm Net (Tensor FISTA-Net) as a decoder for SCI video cameras. Tensor FISTA-Net not only learns the sparsest representation of the video frames through convolution layers, but also reduces the reconstruction time significantly through tensor calculations. Experimental results on synthetic datasets show that the proposed Tensor FISTA-Net achieves average PSNR improvement of 1.63∼3.89dB over the state-of-the-art algorithms. Moreover, Tensor FISTA-Net takes less than 2 seconds running time and 12MB memory footprint, making it practical for real-time IoT applications.

Long Range (LoRa) communication, thanks to its wide network coverage and low energy operation, has attracted extensive attentions from both academia and industry. However, existing LoRa-based Wide Area Network (LoRaWAN) suffers from severe inter-network interference, due to the following two reasons. First, the densely-deployed LoRa ends usually share the same network configurations, such as spreading factor (SF), bandwidth (BW) and carrier frequency (CF), causing interference when operating in the vicinity. Second, LoRa is tailored for low-power devices, which excludes LoRaWAN from using the listen-before-talk (LBT) mechanisms commonly used in wireless communication technologies, such as WiFi and ZigBee -LoRaWAN has to use the duty-cycled medium access policy and thus being incapable of channel sensing or collision avoidance. To mitigate the inter-network interference, we propose a novel solution achieving the online concurrent transmissions at LoRa gateway, called OCT, which recovers collided packets at the gateway and thus improves LoRaWAN's throughput. Moreover, OCT achieves the online concurrent transmission using only LoRa's (de)modulation information, thus can be easily deployed at LoRa gateway. We have implemented and evaluated OCT on USRP platform and commodity LoRa ends, showing OCT achieves: (i) >90% packet reception rate (PRR), (ii) 3 × 10-3bit error rate (BER), (iii) 2x and 3x throughput in the scenarios of two- and three- packet collisions respectively, and (iv) reducing 67% latency compared with state-of-the-art.

Understanding the nature of user-device interactions (e.g., who is using the device and what he/she is doing with it) is critical to many applications including time management, user profiles, and privacy protection. However, in scenarios where mobile devices are shared among family members or multiple employees in a company, conventional account-based statistics are not meaningful. This poses an even bigger problem when dealing with sensitive data. Moreover, fingerprint readers and front-facing cameras were not designed to continuously identify users. In this study, we developed MagPrint, a novel approach to fingerprint users based on unique patterns in the electromagnetic (EM) signals associated with the specific use patterns of users. Initial experiments showed that time-varying EM patterns are unique to individual users. They are also temporally and spatially consistent, which makes them suitable for fingerprinting. MagPrint has a number of advantages over existing schemes: i) Non-intrusive fingerprinting, ii) implementation using a small and easy-to-deploy device, and iii) high accuracy thanks to the proposed classification algorithm. In experiments involving 30 users, MagPrint achieves 94.3% accuracy in classifying users from these traces, which represents an 10.9% improvement over the state-of-the-art classification method.

As the most widely used outdoor navigation system, GPS can provide accurate localization on the horizontal plane. However, the vertical localization accuracy exhibits a poor performance. Vehicles on the elevated road usually receive wrong navigation instructions since GPS fails to detect vehicles' vertical location. In this paper, we present a vertical location system named VLD for vehicles in metropolises mainly leveraging smartphones' barometers, a low-power sensor found in an increasing number of smart devices. When initially on the ground, VLD combines the height and angle detection algorithms to confirm the vertical location with low complexity. Once vehicles have exited the ground and start to travel on the elevated road, a pressure-height model trained by a novel proposed sensor fusion algorithm is activated to measure vehicles' relative height. Then, it tracks the relative height in real time according to a pressure-temperature model which is calibrated by current weather. Comparing the relative height with the single-level elevated road's height, VLD can determine which level vehicles travel on in many highway interchanges and when they exit the elevated road. Experiments covering one month demonstrate that the detection accuracy of VLD exceeds 99% under different weather conditions, and it shows a more accurate relative height measurement compared to available literature, including Baidu Maps and one barometer based application-Altitude. Finally, VLD demonstrates a high efficiency with respect to both the detection delay and power consumption.

Group activities like group dance, military parade, or radio gymnastics have excellent ornamental value with its grand scale and uniform movements, while it also introduces difficulties in practice for coaches to monitor and correct the movements and locations of each participator. Wireless body area network (WBAN) is a promising direction for accurate motion tracking in large-scale group activities. Light-weight sensors can be deployed on participant bodies and transmit motion and channel sensing data through wireless spectrum for further analysis. To keep the high quality of service (QoS) of the WBAN on group activity monitoring and correction, three aspects should be achieved by careful designing: (i) less energy consumption; (ii) higher analysis accuracy; and (iii) lower feedback latency. Due to the low-rankness of motion and channel sensory data, we propose GroupCoach, a Compressed Sensing (CS) based group activity monitoring and correction system. The data is collected and reconstructed by CS, where the spatial and temporal stabilities of group activities are explored for a higher reconstruction accuracy. These reconstructed sensory data are further compared with their anchor values for faulty movement detection and correction. The channel attenuation caused by body shielding is reduced by a near-to-far diffusion model with the consideration of the body impact factor. The correction suggestions are finally fed back to sensors for guidance. Evaluations based on the prototype deployed on real group activity participators prove the high QoS of the GroupCoach. It achieves low sensor energy consumption, high data reconstruction accuracy, accurate faulty motion detection and correction, together with fast alert.

LoRa, which is considered as an appealing wireless technique for Low-Power Wide-Area Networks (LPWANs), has found wide applications in fields such as smart cities, intelligent agriculture. Despite its popularity, there exists a growing concern about secure communications mainly due to the free frequency band and minimalist design specified in LoRa communications. For example, an attacker can forge messages to launch spoofing attack. To mitigate the threat, an authentication mechanism is needed. In this paper, we propose a lightweight node authentication scheme named SLoRa for LoRa networks by leveraging two physical layer features-Carrier Frequency Offset (CFO) and spatial-temporal link signature. In particular, we propose a novel CFO compensation algorithm, and identify slight CFO variations by adopting linear fitting for received upchirps to mitigate the noise's randomness on fine-grained CFO estimation. Besides, we can obtain fine-grained link signatures without the conventional de-convolution operation based on the theoretical analysis. Then, we show how these two physical-layer features complement each other to conquer the drift challenge brought by weather and environment variations. Combining these two features, SLoRa can distinguish whether the received signal is conveyed from a legitimate LoRa node or not. Experiments covering indoor and outdoor scenarios are conducted to demonstrate a high accuracy for node authentication in SLoRa, which is around 97% indoors and 90% outdoors.

The Internet of Vehicles has attracted a lot of attention in the automotive industry and academia recently. We are witnessing rapid advances in vehicular technologies that comprise many components, such as onboard units (OBUs) and sensors. These sensors generate a large amount of data, which can be used to inform and facilitate decision making (e.g., navigating through traffic and obstacles). One particular focus is for automotive manufacturers to enhance the communication capability of vehicles to extend their sensing range. However, the existing short-range wireless access, such as dedicated short-range communication (DSRC), and cellular communication, such as 4G, is not capable of supporting the high volume data generated by different fully connected vehicular settings. Millimeter-wave (mmWave) technology can potentially provide terabit data transfer rates among vehicles. Therefore, we present an in-depth survey of the existing research, published in the last decade, and we describe the applications of mmWave communications in vehicular communications. In particular, we focus on MAC and physical layers and discuss related issues, such as sensing-aware MAC protocol, handover algorithms, link blockage, and beamwidth size adaptation. Finally, we highlight various aspects related to smart transportation applications, and we discuss future research directions and limitations.

Rail transit systems are important parts of modern cities such as the urban subways and intercity trains. During the travelling time, many passengers access the networks via cellular communications for working or entertainment. However, intermittent connection of LTE signals usually decreases the user experiences, especially due to the poor LTE link quality of underground subways. On the other hand, we observe that there are usually multiple cellular operators covering a city. For example, AT&T and T-Mobile in American cities, China Mobile and China Unicom in Chinese cities. Based on the different eNodeB distributions of different operators, we propose to study a new problem cross-operator switch. Unlike the handover between eNodeBs from one operator, cross-operator switch can switch to an eNodeB belonging to other operators. Although current mobile phones support dual SIM cards and Android supports the quick swap between two cards, it is still challenging to determine which eNodeB to switch because of no information exchange between different operators. To address this challenge, we propose a robust Crowdsensing based Switch (CrowdSwitch) solution dedicated for rail transit systems. CrowdSwitch utilizes mass mobile devices of passengers to sense and collect LTE signals along subway tracks, builds the signal heat map (S-Map) in the cloud servers, and finally recommends the optimal switch taking advantages of the known tracks. We implement CrowdSwitch in off-the-shelf mobile phones and conduct extensive experiments on Shanghai Metro. The results show that CrowdSwitch can depict the accurate LTE distribution and always recommend the optimal operator for users to connect.

Fuzzy rough-set-based feature selection is an important technique for big data analysis. However, the classic fuzzy rough set algorithm takes all the data correlations into account, which leads to the centralized computing mode, requiring high computing and memory space resources. With the increasing amount of data in the big data era, the centralized server cannot afford the computation of fuzzy rough set. To enable the fuzzy rough set for big data analysis, in this article, we propose the novel distributed fuzzy rough set (DFRS)-based feature selection, which separates and assigns the tasks to multiple nodes for parallel computing. The key challenge is to maintain the global information on each distributed node without conserving the entire fuzzy relation matrix. We tackle this challenge by a dynamic data decomposition algorithm and a data summarization process on each distributed node. Extensive experiments based on multiple real datasets demonstrate that DFRS significantly improves the runtime, and its feature selection accuracy is nearly the same as the traditional centralized computing.

The smart factory is a representative element reshaping conventional computer-aided industry to data-driven smart industry, while it is nontrivial to achieve cost effectiveness, reliability, mobility, and scalability of smart industrial systems. Data-driven industrial systems mainly rely on sensory data collected from statically deployed sensors. However, the spatial coverage of industrial sensor networks is constrained due to the high deployment and maintenance cost. Recently, mobile crowd sensing (MCS) has become a new sensing paradigm owing to its merits, such as cost effectiveness, mobility, and scalability. Nevertheless, traditional MCS systems are vulnerable to malicious attacks and single point of failure due to the centralized architecture. To this end, in this article we integrate MCS with industrial systems without introducing any additional dedicated devices. To overcome the drawbacks of traditional MCS systems, we propose a blockchain-based MCS system (BMCS). In particular, we exploit miners to verify the sensory data and design a dynamic reward ranking incentive mechanism to mitigate the imbalance of multiple sensing tasks. Meanwhile, we also develop a sensory data quality detection scheme to identify and mitigate the data anomaly. We implement a prototype of the BMCS on top of Ethereum and conduct extensive experiments on a realistic factory workroom. Both experimental results and security analysis demonstrate that the BMCS can secure industrial systems and improve the system reliability.

In a vertical industry alliance, Internet of Things (IoT) deployed in different smart factories are similar. For example, most automobile manufacturers have the similar assembly lines and IoT surveillance systems. It is common to observe the industrial knowledge using deep learning and data mining methods based on the IoT data. However, some knowledge is not easy to be mined from only one factory's data because the samples are still few. If multiple factories within an alliance can gather their data together, more knowledge could be mined. However, the key concern of these factories is the data security. Existing matrix-based methods can guarantee the data security inside a factory but do not allow the data sharing among factories, and thus their mining performance is poor due to lack of correlation. To address this concern, in this article we propose the novel federated tensor mining (FTM) framework to federate multisource data together for tensor-based mining while guaranteeing the security. The key contribution of FTM is that every factory only needs to share its ciphertext data for security issue, and these ciphertexts are adequate for tensor-based knowledge mining due to its homomorphic attribution. Real-data-driven simulations demonstrate that FTM not only mines the same knowledge compared with the plaintext mining, but also is enabled to defend the attacks from distributed eavesdroppers and centralized hackers. In our typical experiment, compared with the matrix-based privacy-preserving compressive sensing (PPCS), FTM increases up to 24% on mining accuracy.

Snapshot compressive imaging (SCI) is a promising approach to capture high-dimensional data with low dimensional sensors. With modest modifications to off-the-shelf cameras, SCI cameras encode multiple frames into a single measurement frame. These correlated frames can then be retrieved by reconstruction algorithms. Existing reconstruction algorithms suffer from low speed or low fidelity. In this paper, we propose a novel reconstruction algorithm, namely, Shearlet enhanced Snapshot Compressive Imaging (SeSCI), which exploits the sparsity of the image representation in both frequency domain and shearlet domain. Towards this end, we first derive our SeSCI algorithm under the alternating direction method of multipliers (ADMM) framework. We then propose an efficient solution of SeSCI algorithm. Moreover, we prove that the improved SeSCI algorithm converges to a fixed point. Experimental results on both synthetic data and real data captured by SCI cameras demonstrate the significant advantages of SeSCI, which outperforms the conventional algorithms by more than 2dB in PSNR. At the same time, the SeSCI achieves a speed-up more than 100× over the state-of-the-art algorithm.

Public vehicle service (PVS), as a paradigm to manage and share large-capacity vehicles for public passenger delivery, is promising to improve the quality of urban transportation. In the PVS system, a command center receives requests sent by passengers, periodically assigns them to public vehicles and schedules vehicle routes to serve the requests. However, in the PVS system, the passengers' waiting time is not well utilized. Moreover, it is observed that the driving distance on low-speed roads accounts for a rather high percentage. These two factors impact on system efficiency. In order to utilize the waiting time, we propose to let passengers walk a short distance instead of standing at their origins. At the same time, the driving distance on low-speed roads will be reduced. In this paper, the closest meeting point algorithm is proposed to address the challenge of determining the best pick-up and drop-off locations. The large-scale simulations show that the passenger walking and the proposed fast-route scheduling strategy can shorten the total vehicle travel distance by 34%.

The number of Internet of Things is growing exponentially, among which the ZigBee devices are being widely deployed, incurring severe collision problem in ZigBee networks. Instead of collision avoidance or packet retransmissions which introduce extra time/energy overhead, existing methods try to decompose multi-packet collision directly. For example, state-of-the-art mZig exploits collision-free chips to decompose the collided chips iteratively, however, suffers from the high bit error rate and low frame reception rate which limit the practical applications. Toward this end, we observe three major issues of existing solutions: 1) all existing solutions adopt the priori-chip-dependent decomposition pattern, leading to the error propagation; 2) the available samples for chip decoding can be scarce, resulting in severe scarce-sample errors; 3) existing solutions assume the consistent frequency offset for consecutive packets, leading to inaccurate frequency offset estimation. To solve these issues in collision decomposition, we propose FORWARD, a novel physical layer design to enable accurate collision decoding in ZigBee. The key idea is to generate all possible overlapping combinations as reference waveforms. The decomposition is determined by comparing the collided signal with the reference waveforms. Such a priori-chip-independent design has the advantages to eliminate the error propagation. To ensure sufficient samples for decoding, FORWARD always choose the longest segment as reference. Furthermore, the real-time channel estimation and frequency offset calibration ensure the accurate collision decoding. We implement FORWARD on USRP platform and evaluate its performance. Experimental results demonstrate that FORWARD reduces bit error rate by order of magnitude and increases frame reception rate by 10% ~ 50% compared with the state-of-the-art.

Despite many existing research on data forwarding in low-duty-cycle wireless sensor networks (WSNs), relatively little work has been done on energy-efficient data forwarding with probabilistic delay bounds. Probabilistic delay guarantees (i.e., delay bounded data delivery with reliability constraints) are of increasing importance for many delay-constrained applications, since deterministic delay bounds are prohibitively expensive to guarantee in WSNs. However, radio duty-cycling and unreliable wireless links pose challenges for achieving the probabilistic delay guarantee in WSNs. In this paper, we propose EEAF, a novel energy-efficient adaptive forwarding technique tailored for low-duty-cycle WSNs with unreliable wireless links. We show the existence of path diversity in low-duty-cycle WSNs, where delay-optimal routing and energy-optimal routing are likely following different paths. The key idea of EEAF is to exploit the intrinsic path diversity to provide probabilistic delay guarantees while minimizing transmission cost. In EEAF, an early arriving packet will be adaptively switched to the energy-optimal path for energy conservation. Delay quantiles are derived at each node in a distributed manner and are used as the guidelines in the adaptive forwarding decision making. Extensive testbed experiment and large-scale simulation show that EEAF effectively reduces the transmission cost by 12%~25% with probabilistic delay guarantees under various network settings. In addition, we extend the EEAF technique with data aggregation for event-based traffic scenarios. Evaluation using publicly available WSN event traffic traces yields very encouraging results with up to 40% energy saving in probabilistic delay bounded data delivery.

Datacenter is an irreplaceable and crucial infrastructure to power the ever-growing Internet services and applications. In response to today's application constraints (e.g., throughput, end-to-end delay, bandwidth), most datacenter networks are designed to maintain multiple parallel paths between any given pair of hosts. Consequently, multi-path routing has emerged as a technology of choice which can fully utilize the dormant path diversity. However, due to the growing heterogeneity of datacenter topologies and resource requirements, it demands intensive efforts to configure the right multi-path routing algorithms in real deployment according to the specific service targets. Such user burdens are caused by the lack of empirical knowledge about characteristics of various routing algorithms. To fill this gap, we develop a customized simulator DRE based on OMNET++ simulation environment and INET framework, and measure 5 state-of-the-art multi-path routing algorithms in datacenter covering various topologies and metrics. Apart from evaluating the standard macro metrics, we propose three new micro metrics to explore path-level characteristics, which have not been studied before. Our simulator provides a user-friendly interface for users who are interested in datacenter measurements, and the measurement results can promote future multi- path routing algorithm designs.

Surfing the Internet with mobile phones is a popular fashion to kill time in subways. However, users usually meet the intermittent connectivity caused by the high- speed movement, leading to poor user experience. We observe that almost every city is covered by multiple cellular operators. In addition, more and more mobile phones support multiple SIM cards. These motivate us to leverage multiple cellular operators together for a reliable connectivity, which is also a trend for next generation cellular network. It is challenging to build collaborations between operators, because there is no interaction between different operators and the traditional handover methods would consume much time on cross-operator cellular detection. To address these challenges, we propose a Crowdsensing based Switch (CrowdSwitch) system between multiple cellular operators in subways. CrowdSwitch uses a large number of mobile phones to measure and collect wireless signals from different locations along subway tracks, uploads them to cloud servers for analysis, and finally recommends the optimal switch strategy to users. We implement CrowdSwitch in off-the-shelf mobile phones and conduct extensive experiments on Shanghai Metro. The results show that CrowdSwitch can depict the accurate LTE distribution and recommend the optimal operator for users to connect.

Internet of Things (IoT) plays an indispensable role in our daily life, in many cases, IoT systems are implemented following the client-server paradigm, which are vulnerable to single point of failures and malicious attacks. Due to the resilience and security promise of blockchain, the idea of combining blockchain and IoT has gained considerable attention in recent years. However, blockchains are power-intensive and low-throughput, which may not suitable for power-constrained IoT devices. To tackle these challenges, we present B-IoT, a blockchain based IoT system with credit-based consensus mechanism. We propose a credit-based proof-of-work (PoW) mechanism for IoT devices, which enhances security and improves transaction efficiency simultaneously. In order to protect the confidentiality of sensitive IoT data, we design a data authority management method to regulate the access to sensor data. In addition, our system is built based on a directed acyclic graph (DAG)-structured blockchain, which is more efficient than the satoshi-style blockchain. We implement a prototype of B-IoT on Raspberry Pi, and conduct case studies of a smart factory. Extensive evaluation and analysis results demonstrate that the proposed credit-based PoW mechanism and data access control are practical for IoT.

As wireless communication is tailored for low-power devices while the number of Internet of Things is growing exponentially, the collision problem in ZigBee is worsen. The classical approaches of solving collision problems lie in collision avoidance and packet retransmission, which could incur considerable overhead. The new trend is to decompose multipacket collision directly, however, the high bit error rate limits its practical applications. Toward this end, we observe three major issues in the existing solutions: 1) all existing solutions adopt the priori-chip-dependent decomposition pattern, leading to the error propagation; 2) the available samples for chip decoding can be scarce, resulting in severe scarce-sample errors; 3) existing solutions assume the consistent frequency offset for consecutive packets, leading to inaccurate frequency offset estimation. To solve the issues of collision decomposition in ZigBee, we propose FORWARD, a novel physical layer design to enable highly accurate collision decomposition in ZigBee. The key idea is to generate all possible collided combinations as reference waveforms. The decomposition is determined by comparing the collided signal with the reference waveforms. Such a priori-chip-independent design has the advantages to eliminate the cumulative errors incurred from error propagation. When decoding, FORWARD always choose the longest segment to ensure sufficient samples for decoding. Furthermore, the recursive calibration design is approaching the real-time frequency offset and dynamically compensates the reference waveform. We implement FORWARD on USRP based testbed and evaluate its performance. Experimental results demonstrate that FORWARD reduces bit error rate by 4.96× and increases throughput 1.46~2.8× compared with the state-of-the-art mZig.

We present mLoRa in this paper, a novel protocol that can decode multiple collided packets simultaneously from different transmitters in LoRa networks. As a recently proposed wireless technology designed for low-power wide-area networks, LoRa has been proverbially employed in many fields, such as smart cities, intelligent agriculture, and environmental monitoring. In LoRa networks, a star-of-stars topology is conventionally implemented, in which thousands of nodes connect to a single gateway. Accordingly, the convergecast scenario becomes common. For example, in intelligent agriculture, multiple sensor nodes send information with respect to the soil temperature and humidity to a LoRa gateway. Regularly, simultaneous transmissions result in the severe collision problem. Meanwhile, the ALOHA protocol is widely applied in LoRa networks, which further aggravates the collision problem. To conquer this challenge, we propose a protocol named mLoRa for multi-packet reception in LoRa networks, leveraging unique features inherent in LoRa’s physical layer including chirp spread spectrum (CSS), M-FSK modulation, and demodulation. In addition, design enhancements are developed to mitigate the noise and frequency offset influence. We implement mLoRa on a six-node testbed with USRPs. Experiment results demonstrate that mLoRa enables up to three concurrent transmissions. Correspondingly, mLoRa based throughput is around 3 times more than the conventional LoRa.

Fuzzy rough set based feature selection is a widely adopted technique for big data analysis. However, the high accuracy of this technique depends on all the data correlations, so that it always works in the centralized computing mode. With the increasing data volume, the centralized server, especially its computation capability and memory space, cannot afford the computing of fuzzy rough set. To enable the fuzzy rough set for big data analysis, in this paper, we propose the novel Distributed Fuzzy Rough Set (DFRS) based feature selection in cloud computing, which separates and assigns the tasks to multiple nodes for parallel computing. The key challenge is to maintain the global information on each distributed node without conserving the entire fuzzy relation matrix. We tackle this challenge by a dynamic data decomposition algorithm and a data summarization process on each distributed node. Extensive experiments based on multiple real datasets demonstrate that DFRS significantly improves the runtime and its feature selection accuracy is nearly the same as the traditional centralized computing.

Increasing the vitality of facial expression for characters in videos can greatly improve the user experience on entertainments, like in films, animations, news broadcasting, or even a static painting. Recent advances have been made on facial expression migration, especially by GANs for better performance, while most of them cannot be automatically applied in consecutive frames. In this paper, we propose GANemotion, an automatic facial expression migration architecture for real-time videos. Three main modules are designed for this purpose: audio emotion classification module, facial expression classification module, and facial expression migration module on GANs. The outputs of the first two modules will be the inputs of the third module, where the emotion type acquired from text analysis will be the target generation label and image from facial classification is the object for processing. Expression attention algorithm and standard AU library are specially designed for avoiding distortion and processing on non-real world characters. Experiments have been applied to each module and the whole architecture respectively. They show the feasibility of GANemotion with higher classification accuracy, and vivid generation, breaking the limits of non-real world characters and low illumination conditions.

With the proliferation of IoTs, massive deployments of ZigBee devices intensify the collision, a fundamental problem in wireless communication. Conventional solutions exploit the protocol based on CSMA to avoid collision, which incurs considerable overhead. Recently, new solutions which focus on concurrent transmission via collision decomposition are proposed instead of collision avoidance. However, existing approaches to collision decomposition in ZigBee suffer the problems of error propagation and scarce-sample error. To make up the weakness of existing solutions, we propose a novel solution, reZig, which leverages the generated reference waveform in the receiver to infer each single waveform in the collision. By inferring the chip independently, reZig is error-propagation-free. As there are multiple segments provided to decode one chip, reZig can select the segment with most raw samples to ensure the decoding reliability. We implement reZig on the USRP N210 testbed. Experiments demonstrate that reZig achieves the 1.46~ 2.8× throughput compared to mZig, the state-of-the-art collision-decomposition approach to ZigBee.

In this paper, we develop a new library TenDeC++ for tensor decompositions in C++. TenDeC++ supports popular tensor decomposition functions including Canonical Polyadic, Tucker, tensor-train, and t-SVD, assisting C++ programmers to shorten the development cycle of deep learning applications. Compared with the resource-intensive Python and MATLAB, C++ has the nature advantages on fast running time and high compatibility. To further explore potentials of C++, we propose a novel underlying technology PointerDefomer leveraging the unique pointer. Since the transformation between tensor and size-specific matrix is indispensable in tensor decompositions, PointerDefomer can virtually achieve such a transformation by controlling the movement of pointer in memory address. As a result, the conventional transformation steps can be skipped to accelerate the decomposition process and there is no memory needed for saving the intermediate results of tensor transformation. In our experiment, TenDeC++ reduces decomposition time and support larger size of tensor compared with the classic Tensorly in Python and TensorLab in MATLAB, respectively.

Wireless surveillance systems are rapidly gaining popularity due to their easier deployability and improved performance. However, cameras inside are generating a large amount of data, which brings challenges to the transmission through resource-constrained wireless networks. Observing that most collected consecutive frames are redundant with few objects of interest (OoIs), the filtering of these frames can dramatically relieve the transmission pressure. Additionally, real-world environment may bring shielding or blind areas in videos, which notoriously affects the accuracy of frame analysis. The collaboration between cameras facing at different angles can compensate for such accuracy loss.

With the increase of data driven vehicular applications, existing networks cannot satisfy the communication requirements. Therefore, 5G millimeter wave (mmWave) communications, which can offer multi-gigabit data rate, hold potential to be utilized in vehicular networks. On one hand, due to the densely deployed 5G base stations, frequent handover will largely decrease the quality of service, where recent handover is at hundred-millisecond level. On the other hand, mmWave links are easily broken by obstacles because of short wavelength. Yet existing handover protocols do not consider the blockage problem, which frequently occurs in mmWave based networks. To address these problems, we propose a real-time handover protocol called mmHandover for 5G mmWave vehicular networks leveraging mmWave antennae. In mmHandover, multiple antennae in one array are divided into two parts: pre-connected antennae and data transmission antennae. In parallel, pre-connected antennae build the connection with multiple candidate base stations before activation based on a designed pre-connection strategy, while data transmission antennae are responsible for data delivery with the currently connected base station. When handover is triggered or blockage happens, one of the pre-connected links will convert into data transmission link, thus realizing almost seamless handover. Finally, real data-driven simulations demonstrate the efficiency and effectiveness of mmHandover. Compared with standard 4G/WiFi handover protocols, mmHandover greatly reduces the delay from more than 500μs to about 1000μs. Besides, the delay gap will get widened coupled with increase in the number of vehicles.

Vehicle localization service is a fundamental component of intelligent transportation systems. The widely used satellite navigation systems perform poorly in urban areas because the lines of sight to satellites are blocked by complex terrain characteristics, e.g., buildings, elevated streets and interchanges. In this paper, we design RadioLoc, a novel system achieving accurate, efficient, all-terrain vehicle localization with two key design points. First, RadioLoc harvests the frequency modulation (FM) signal, which has a higher availability than satellite signal in complex terrains, as the signal source for localization. Second, RadioLoc integrates modern machine learning techniques into the processing of FM signals to efficiently learn the accurate vehicle localization in all-terrain environments. We validate the feasibility of FM-based vehicle localization and corresponding challenges and practical issues via field tests (e.g., signal distortion, signal inconsistency and limited in-vehicle radio bandwidth), and develop a series of advanced techniques in RadioLoc to address them, including a new multipath delay spread filter, a reconstructive PCA denoiser, a tailored FM feature extractor, an adaptive batching technique and a frequency sweep technique. We implement a prototype of RadioLoc and perform extensive field experiments to evaluate its efficiency and efficacy. Results show that (1) RadioLoc achieves a real-time localization latency of less than 100 milliseconds; (2) RadioLoc achieves a worst-case localization accuracy of 99.6% even in an underground parking lot, and (3) the horizontal error of RadioLoc is only one sixth of a dedicated GPS device even when the vehicle is moving at a high-speed (i.e., 80 km/h) in a complex highway scenario.

The automotive industry is increasingly employing software- based solutions to provide value-added features on vehicles, especially with the coming era of electric vehicles and autonomous driving. The ever-increasing cyber components of vehicles (i.e., computation, communication, and control), however, incur new risks of anomalies, as demonstrated by the millions of vehicles recalled by different manufactures. To mitigate these risks, we design B-Diag, a battery-based diagnostics system that guards vehicles against anomalies with a cyber-physical approach, and implement B-Diag as an add-on module of commodity vehicles attached to automotive batteries, thus providing vehicles an additional layer of protection. B-Diag is inspired by the fact that the automotive battery operates in strong dependency with many physical components of the vehicle, which is observable as correlations between battery voltage and the vehicle's corresponding operational parameters, e.g., a faster revolutions-per-minute (RPM) of the engine, in general, leads to a higher battery voltage. B-Diag exploits such physically-induced correlations to diagnose vehicles by cross-validating the vehicle information with battery voltage, based on a set of data-driven norm models constructed online. Such a design of B-Diag is steered by a dataset collected with a prototype system when driving a 2018 Subaru Crosstrek in real-life over 3 months, covering a total mileage of about 1, 400 miles. Besides the Crosstrek, we have also evaluated B-Diag with driving traces of a 2008 Honda Fit, a 2018 Volvo XC60, and a 2017 Volkswagen Passat, showing B-Diag detects vehicle anomalies with >86% (up to 99%) averaged detection rate.

The development of smart homes has advanced the concept of user authentication to not only protecting user privacy but also facilitating personalized services to users. Along this direction, we propose to integrate user authentication with human-computer interactions between users and smart household appliances through widely-deployed WiFi infrastructures, which is non-intrusive and device-free. In this paper, we propose FingerPass which leverages channel state information (CSI) of surrounding WiFi signals to continuously authenticate users through finger gestures in smart homes. We investigate CSI of WiFi signals in depth and find CSI phase can be used to capture and distinguish the unique behavioral characteristics from different users. FingerPass separates the user authentication process into two stages, login and interaction, to achieve high authentication accuracy and low response latency simultaneously. In the login stage, we develop a deep learning-based approach to extract behavioral characteristics of finger gestures for highly accurate user identification. For the interaction stage, to provide continuous authentication in real time for satisfactory user experience, we design a verification mechanism with lightweight classifiers to continuously authenticate the user's identity during each interaction of finger gestures. Experiments in real environments show that FingerPass can achieve 91.4% authentication accuracy, and 186.6ms response time during interactions.

To build a secure wireless networking system, it is essential that the cryptographic key is known only to the two (or more) communicating parties. Existing key extraction schemes put the devices into the physical proximity, and utilize the common inherent randomness between the devices to agree on a secret key, but they often rely on custom devices and have low bit rate. In this paper, we seek a key extraction approach that only leverages off-the-shelf mobile devices, while achieving significantly higher key generation efficiency. The core idea of our approach is to exploit fast varying inaudible acoustic channel for generating enough randomness and wireless parallel communication for exchanging reconciliation information to improve the key generation rate. We have carefully studied and validated the feasibility of our approach through both theoretical analysis and a variety of measurements. We implement our approach on different mobile devices and conduct extensive experiments in different real scenarios. The experiment results show that our approach achieves high efficiency and satisfactory robustness. Compared with the state of art methods, our approach improves the key generation rate by 38.46% and reduces the bit mismatch ratio by 42.34%.

Given the increasing amount of time people spent on driving, the physical and mental health of drivers is essential to road safety. Breathing patterns are critical indicators of the well-being of drivers on the road. Existing studies on breathing monitoring require active user participation of wearing special sensors or relatively quiet environments during sleep, which are hardly applicable to noisy driving environments. In this work, we propose a fine-grained breathing monitoring system, BreathListener, which leverages audio devices on smartphones to estimate the fine-grained breathing waveform in driving environments. By investigating the data collected from real driving environments, we find that Energy Spectrum Density (ESD) of acoustic signals can be utilized to capture breathing procedures in driving environments. To extract breathing pattern in ESD signals, BreathListener eliminates interference from driving environments in ESD signals utilizing background subtraction and Ensemble Empirical Mode Decomposition (EEMD). After that, the extracted breathing pattern is transformed into Hilbert spectrum, and we further design a deep learning architecture based on Generative Adversarial Network (GAN) to generate fine-grained breathing waveform from the Hilbert spectrum of extracted breathing patterns in ESD signals. Experiments with 10 drivers in real driving environments show that BreathListener can accurately capture breathing patterns of drivers in driving environments.

Fine-grained and complete Channel State Information (CSI) is essential for emerging CSI-based activity recognition applications. However, many probe packets collected for CSI measurements may be lost due to co-channel interferences and other malfunctions in practice, such as link interruptions, and thus limit the further applications of these CSI-based activity recognitions. To overcome this limitation, we propose an IM proved cO mpressive Sensing bA sed mIssing packet reC overy method, named IMOSAIC, to locate the lost probe packets and to reconstruct the missing CSIs, and thus improve the accuracy and the robustness of CSI-based activity recognitions. The key idea is to trace the probe packet flow to locate the positions of lost packets, derive the CSI Matrix from CSI measurements, and use improved compressive sensing technique to reconstruct the missing CSIs. We mainly address challenges in locating the lost packets, transforming CSI measurements into CSI Matrix, and digging up CSI measurement correlations and inherent low-rank properties to reconstruct the lost packets. Furthermore, experiment results show that IMOSAIC outperforms existing interpolation methods on reconstructing the lost packets, and can achieve an average recovery accuracy of 80.21%, when 90% of packets are lost, and the reconstructed CSI datasets can improve the activity recognition accuracy obviously.

Software-defined Internet of Vehicles (SDIoV) has emerged as a promising field of study as it could overcome the shortcomings of traditional vehicular networks, such as offering efficient data transmission and traffic shaping in different vehicular scenarios to satisfy all the requirements of applications on the fly. Although routing solutions are lightly addressed for SDIoV, there are many limitations of routing protocols unaddressed in such environment. More precisely, shortest path routing algorithms are mostly focused in the state of the arts. This paper presents quality of service aware routing algorithm that forwards packets toward the most reliable and connected path to the destination. Particularly, candidate routes should satisfy metrics, such as signal to interference and noise ratio (SINR) constraint and have the highest probability of connectivity. To address these issues, we have formulated a discrete optimization problem to favor the best route among candidate paths and proposed the modified laying chicken algorithm (LCA) that results better results than the traditional approaches. We have mathematically analyzed the probability of connectivity along with the SINR metric. Moreover, a multiscore function based on traffic density and greediness factor is proposed to make intelligent decision at the intersections. Simulation results are used to validate the superiority of the proposed routing approach over the existing solutions.

Industrial Internet of Things (IIoT) plays an indispensable role for Industry 4.0, where people are committed to implement a general, scalable, and secure IIoT system to be adopted across various industries. However, existing IIoT systems are vulnerable to single point of failure and malicious attacks, which cannot provide stable services. Due to the resilience and security promise of blockchain, the idea of combining blockchain and Internet of Things (IoT) gains considerable interest. However, blockchains are power-intensive and low-throughput, which are not suitable for power-constrained IoT devices. To tackle these challenges, we present a blockchain system with credit-based consensus mechanism for IIoT. We propose a credit-based proof-of-work (PoW) mechanism for IoT devices, which can guarantee system security and transaction efficiency simultaneously. In order to protect sensitive data confidentiality, we design a data authority management method to regulate the access to sensor data. In addition, our system is built based on directed acyclic graph -structured blockchains, which is more efficient than the Satoshi-style blockchain in performance. We implement the system on Raspberry Pi, and conduct a case study for the smart factory. Extensive evaluation and analysis results demonstrate that credit-based PoW mechanism and data access control are secure and efficient in IIoT.

ZigBee is a widely used wireless technology in low-power and short-range scenarios such as the Internet of Things, sensor networks, and industrial wireless networks. However, the traditional ZigBee supports only one data rate, 250 Kbps, which thoroughly limits ZigBee's efficiency in dynamic wireless channels. In this paper, we propose Mrs. Z, a novel physical layer design to enable multi-rate selection in ZigBee with lightweight modification on the legacy ZigBee modules. The key idea is to change the single spectrum spreading length to multiple ones. Correspondingly, to support the rate adaptation to the channel variations, we propose a bit-error-based rate selection scheme, which predicts BER by leveraging the physical properties of ZigBee to calculate the confidence for each symbol in transmission. Then, the receiver selects the rate based on the negative impact on throughput incurred by bit errors and gives feedback to the transceiver. We implement Mrs. Z on USRPs and evaluate its performance in different scenarios. Experiment results demonstrate that Mrs. Z achieves about 1.15, 1.2, and 1.8 × average throughput compared to the classic smart pilot, softrate, and the traditional ZigBee.

To prevent users privacy from leakage, more and more mobile devices employ biometric-based authentication approaches, such as fingerprint, face recognition, voiceprint authentications, and so on, to enhance the privacy protection. However, these approaches are vulnerable to replay attacks. Although the state-of-art solutions utilize liveness verification to combat the attacks, existing approaches are sensitive to ambient environments, such as ambient lights and surrounding audible noises. Toward this end, we explore liveness verification of user authentication leveraging users mouth movements, which are robust to noisy environments. In this paper, we propose a lip reading-based user authentication system, LipPass, which extracts unique behavioral characteristics of users speaking mouths through acoustic sensing on smartphones for user authentication. We first investigate Doppler profiles of acoustic signals caused by users' speaking mouths and find that there are unique mouth movement patterns for different individuals. To characterize the mouth movements, we propose a deep learning-based method to extract efficient features from Doppler profiles and employ softmax function, support vector machine and support vector domain description to construct multi-class identifier, binary classifiers and spoofer detectors for mouth state identification, user identification and spoofer detection, respectively. Afterward, we develop a balanced binary tree-based authentication approach to accurately identify each individual leveraging these binary classifiers and spoofer detectors with respect to registered users. Through extensive experiments involving 48 volunteers in four real environments, LipPass can achieve 90.2% accuracy in user identification and 93.1% accuracy in spoofer detection.

Large-scale battery packs are commonly used in applications such as electric vehicles (EVs) and smart grids. Traditionally, to provide stable voltage to the loads, voltage regulators are used to convert battery packs’ output voltage to those of the loads’ required levels, causing power loss especially when the difference between the supplied and required voltages is large or when the load is light. In this article, we address this issue via a reconfiguration framework for the battery system. By abstracting the battery system as a cell graph, we develop an adaptive reconfiguration algorithm to identify the desired system configurations based on real-time load requirements. Our design is evaluated via both prototype-based experiments, EV driving trace-based emulations, and large-scale simulations. The results demonstrate an extended system operation time of up to 5×, especially when facing severe cell imbalance.

Flow monitoring is widely applied in softwaredefined networks for monitoring network performance. Especially, the detection on heavy hitters can prevent the Distributed Denial of Service attack. However, many existing approaches fall in one of two undesirable extremes: (i) inefficient collection where only accuracy is concerned in the method; (ii) low accuracy caused by the sacrifice with fast detection. As a result, we aim to find a balance between the accuracy and efficiency of flow monitoring, where the network resources can be saved and the error rate can also be confined simultaneously. In this paper, we present ReFeR, a novel “Report-FeedbackReport” scheme to improve the detection efficiency of heavy item detecting while ensuring low error rate of the measurement. ReFeR leverages the binary order of magnitude of item measurement to replace the long statistical information shared between switches and controller; after the items are analyzed with the magnitude, only fewer uncertain items are involved in further detection, where their information (i.e., significant digits) is provided for final judgment. Theoretical analysis and simulated evaluation have proved the effectiveness of our solution. ReFeR keeps the error rate under 1% and the saving rate larger than 20% in most cases as the selecting fraction α> 524, which guarantees both high efficiency and low error rate compared with existing methods.

ZigBee, a low-power wireless communication technology, has been used in various applications such as smart health/home/buildings. The proliferation of ZigBee-based applications (and thus devices), however, makes the concurrent transmissions - i.e., multiple transmitters send packets to the same receiver at the same time - common in practice, leading to inevitable collisions. To facilitate the concurrent transmissions of ZigBee, we design Pre/Post-amble based Multi-packet reception (PPM), a method that recovers the collided ZigBee messages by exploiting their collision-free chips and the overlapped chips in their pre/post-ambles. Such a collision recovery of PPM reduces the retransmissions caused due to collisions, facilitating the realization green ZigBee. We have prototyped and evaluated PPM with USRP, showing PPM recovers the collided messages with bit-error-rates in the order of 10-6, which is magnitudes lower than state-of-the-art methods.

Mobile Crowdsensing (MCS) is a promising paradigm that utilizes ubiquitous mobile devices to collect environmental data. Specially, location data is critical among all kinds of data because most MCS applications are location-based. Faulty data and missing values, however, may exist in the collected location data due to various reasons. This brings forth an important issue of detecting faulty location data in the presence of missing values. To address this issue, we propose I(TS, CS), a joint faulty data detection framework that combines TimeSeries and Compressive Sensing techniques. The framework adopts a DETECT-and-CORRECT approach to iteratively detect faulty data and reconstruct the dataset, which bypasses the tradeoff between false positive ratio (Type-I error) and false negative ratio (Type-II error), and thus detects more faulty data without increasing False Positive Rate. We have evaluated the proposed I(TS, CS) framework based on a real trace consisting of the trajectories of 2000 taxies, showing I(TS, CS) dramatically improve the performance of both faulty data detection and data reconstruction.

Consistent routing update based on Software-Defined Networks (SDN) is a complicated problem due to the asynchronous and distributed data plane. Existing ordered update approaches mostly focus on the consistent routing update problem for unicast other than multicast, which should guarantee two consistencies, drop-freeness and duplicate-freeness. In this paper, we propose Shifter, a novel dynamic ordered update scheme for consistent multicast routing update based on SDN to guarantee both consistencies. Shifter advocates configuring inport match field in the forwarding rules to avoid duplicate. In order to guarantee drop-freeness, Shifter employs a dependency graph to dynamically schedule update operations, and uses a greedy solution to solve a subproblem named Replace Operation Tree Migration Problem (ROTMP). We conduct simulations to evaluate Shifter and find that Shifter can give a near optimal solution of ROTMP with very few rounds and little runtime for multicast routing update scenarios. To the best of our knowledge, Shifter is the first ordered update scheme to guarantee the two consistencies simultaneously.

Smart devices (e.g., smartphones or tablets) have become an indispensable part of our daily lives for conducting mobile payment transactions, and storing both corporate and personal sensitive data. As a result, unauthorized access to smart devices can result in a catastrophic security breach. Lock screen provides the first line of defense against unauthorized access to smart devices, where users typically use the PIN, the pattern of drawing, or biometric to unlock their devices. Unfortunately, recent studies have revealed that individual unlocking methods are insufficient to prevent unauthorized access to smart devices. In this paper, we aim to increase the security barrier of smart device unlocking. We present the CP3, a combined unlocking framework to achieve highly secure and usable authentication for commodity smart devices. We address several challenges of combing unlocking methods from different modalities, such as the high reliability and low latency. We implement a prototype of our approach based on the Android platform, which selects the fingerPrint authentication, bluetooth transmission Power authentication and facial Pattern verification as our typical Combination for the secure unlocking. We have made the source code of our implementation public. Real-world experiments demonstrate the effectiveness of our solution. CP3achieves 88 % accuracy and 2.88s operation latency, which guarantees both good user experience and high security level compared with existing methods.

Modern bike sharing system, in which bikes can be parked freely, extends the flexibility of traditional bike sharing system and thus has greatly facilitated urban transportation. However, the balance of such system is often broken by the user behaviors. And how to manage a large number of bikes which parked randomly in a city is a difficult problem. To tackle this problem, we propose a two-step solution. First, we deal with the bike trajectory data and design the Spatial-Temporal Bike Flow Prediction (ST-BFP) model, which is a convolutional network based on residual framework with history external factors to predict the bike flows. Second, to make the system return to balance state as soon as possible, we propose an Improved Local Search Algorithm (ILSA) for path planning with multiple carriers based on forecast result, which schedules multiple carriers in real time to complete the rebalance task collaboratively. Finally, we validate our model and algorithm via real-data based experiment. Experimental results demonstrate that our method can balance the entire system efficiently.

Modern high-end scientific and technological robots have been utilized in various fields. With regard to distribution, reliability, flexibility, and economy, swarm robots can accomplish more arduous tasks in parallel and demonstrate a superior performance compared to single robot. However, information interaction, which causes extra time overhead, is essential to realize synchronization or coordination in multi robot system. This paper focuses on improving the edge coverage ability of base stations especially when swarm robots cover a wide range. It proposes a novel collaborative communication protocol named Co2-Robot for these robots in order to carry out distributed beamforming, thus enhancing the coverage range. In particular, efficient strategies are designed to cut down the time overhead among swarm robots. Subsequently, we develop a novel cluster head selection scheme to be responsible for the parallel operations. Then, distributed beamforming is performed to improve the uplink coverage when no signal from anyone of swarm robots can reach the base station. In addition, several practical user-cases are considered and analyzed in distributed beamforming, in order to enhance the robustness of this parallel system. Finally, extensive simulations show that Co2-Robot will just result in a small amount of time overhead, which is acceptable in most scenarios. Furthermore, it can substantially extend the coverage range up to nearly 1000m while single robot can just cover a coverage range of more than 100m.

Exploring and utilizing indoor white spaces (vacant VHF and UHF TV channels) have been recognized as an effective way to satisfy the rapid growth of the radio frequency (RF) demand. Although a few methods of exploring indoor white spaces have been proposed in recent years, they only focus on the exploration of the current indoor white spaces. However, due to the dynamic nature of the spectrum and the time delay in the process of exploration, users often cannot get accurate white space information in time, resulting in issues, such as spectrum utilization conflicts or inadequate white space utilization. To solve the problem, in this paper, we first perform an indoor TV spectrum measurement to study how the spectrum state changes over time and the spatio-temporal-spectral correlation of spectrum. Then, we propose a real-time aCcurate indoOR whiTe spacE predictioN mechanism, called CORTEN. CORTEN can predict the white space distribution for various time spans with high accuracy. Furthermore, we build a prototype of CORTEN and evaluate its performance based on the real-world measured data. The evaluation results show that CORTEN can predict accurately 38.7% more indoor white spaces with 51.3% less false alarms compared with the baseline approach when predicting the white spaces one hour ahead.

Mobile CrowdSensing has played an important role in our daily life. Data quality evaluation and user recruitment are both important problems in CrowdSensing. Recruiting users who will provide high-quality data guarantees the success of a task. In this paper, we will recruit users based on the data quality. First, by exploiting the historical data that users performed on tasks, we use Compressive Sensing(CS) to predict the data quality that a user will achieve on a task which he has never done before. By partitioning the matrix according to the similarity between users, we propose G(grouping) C(Compressive) S(Sensing). Compared with original CS, GCS is more efficient and has higher precision. Then, we use the predicted data quality to guide user recruitment. We consider a general scenario in the real world. For a task, we expect to use as short as possible time to achieve the expected quality. We both consider offline and online scenarios, and we design the greedy approximation algorithms Off-QBUR (Offline Quality-Based User Recruitment) with logarithmic approximation ratio and On-QBUR (Online Quality-Based User Recruitment) algorithm with linear approximation ratio respectively. We use a real-world dataset to evaluate the prediction of the data quality, and the experiment result shows that our method is efficient and can predict data quality with high precision.

Mobile crowd sensing (MCS) is the special case of crowdsourcing, which leverages the smartphones with various embedded sensors and user's mobility to sense diverse phenomenon in a city. Task allocation is a fundamental research issue in MCS, which is crucial for the efficiency and effectiveness of MCS applications. In this paper, we specifically focus on the task allocation in MCS systems. We first present the unique features of MCS allocation compared to generic crowdsourcing, and then provide a comprehensive review for diversifying problem formulation and allocation algorithms together with future research opportunities.

Recent physical-layer designs capable of decoding multi-packet collisions demonstrate great potential for improving the network performance. Current network protocols, however, tailor the traditional physical layer to avoid collisions and thus cannot fully exploit the benefits of concurrent transmission techniques. In this paper, we propose an innovative generic concurrent transmission aware routing design called mShare. The mShare design exploits the benefits of these techniques by scheduling concurrent senders to utilize co-owned receiver(s) in parallel. This design significantly increases the available number of routing choices and thus improves the network performance. To illustrate the versatility of our design, we test mShare in three settings: unicast, opportunistic routing, and data collection (convergecast). The performance of mShare is evaluated with physical testbed experiments running on USRP and simulations. The experimental results show that compared to conventional designs, mShare: 1) improves 277% of the throughput in unicast; 2) saves 78% of transmissions in opportunistic routing; and 3) reduces 70% of the delivery delay in data collection.

The collection of sensory data is crucial for cyber‐physical systems. Employing mobile agents (MAs) to collect data from sensors offers a new dimension to reduce and balance their energy consumption but leads to large data collection latency due to MAs’ limited velocity. Most existing research effort focuses on the offline mobile data collection (MDC), where the MAs collect data from sensors based on preoptimized tours. However, the efficiency of these offline MDC solutions degrades when the data generation of sensors varies. In this paper, we investigate the on‐demand MDC; that is, MAs collect data based on the real‐time data collection requests from sensors. Specifically, we construct queuing models to describe the First-Come-First-Serve‐based MDC with a single MA and multiple MAs, respectively, laying a theoretical foundation. We also use three examples to show how such analysis guides online MDC in practice.

The Industrial Internet of Things (IIoT) is the use of Internet of Things (IoT) technologies in manufacturing. The vehicular ad hoc networks (VANETs) are a typical application of IIoT. Benefiting from Dedicated Short‐Range Communication (DSRC) technology, vehicles can communicate with each other through wireless manner. Therefore, road safety is able to be greatly improved by the broadcast of safety messages, which contain vehicle’s real‐time speed, position, direction, etc. In existing DSRC, safety messages are broadcasted at a fixed frequency by default. However, traffic conditions are dynamic. In this way, there are too many transmission collisions when vehicles are too dense and the wireless channel is underused when vehicles are too sparse. In this paper, we address broadcast congestion issue in DSRC and propose lightweight adaptive broadcast (LAB) control for DSRC safety message. The objectives of LAB are to make full use of DSRC channel and avoid congestion. LAB meets two key challenges. First, it is hard to adopt a centralized method to control the communication parameters of distributed vehicles. Furthermore, the vehicle cannot easily acquire the channel conditions of other vehicles. To overcome these challenges, channel condition is attached with safety messages in LAB and broadcast frequency is adapted according to neighboring vehicles’ channel conditions. To evaluate the performance of LAB, we conduct extensive simulations on different roads and different vehicle densities. Performance results demonstrate that LAB effectively adjusts the broadcast frequency and controls the congestion.

In recent years we have witnessed the rapid development of smart bicycles. For example, Mobike1 is able to interact with smartphones. As we all known, accurate bicycle localization system is one of the most critical technologies for the development of smart bicycles. However, GPS's error is at meter-level and it performs poorly under skyscrapers and in tunnels.

ZigBee is a widely used wireless technology in low-power and short-range scenarios such as Internet of Things (IoT), sensor networks, and industrial wireless networks. However, the standard ZigBee supports only one data rate, 250Kbps, which thoroughly limits ZigBee's efficiency in dynamic wireless channels. In this paper, we propose Mrs.Z, a novel physical layer design to enable multi-rate selection in ZigBee. The key idea is to change the single spectrum spreading length to multiple ones. Correspondingly, to gracefully adapt to the channel variations, we propose a BER-based rate selection scheme, dividing bit errors into two categories: errors caused by the exceeding despreading threshold, which can be discovered in the physical layer, and caused by incorrect despreading, which is not visible until cyclic redundancy check (CRC) in the media access control (MAC) layer. Then, the receiver selects the rate based on the underlying negative impacts incurred by them and feedbacks to the transceiver. We implement Mrs.Z on USRPs and evaluate its performance in different scenarios. Results demonstrate that Mrs.Z achieves an improvement of 20% and 80% compared to the classic SoftRate and the standard ZigBee.

Wireless sensor networks (WSNs) have been widely used in industrial systems that demand a high degree of reliability and real-time performance in communications. However, because of limited network resources and delays caused by transmission conflicts and channel contention, many industrial applications cannot meet these demands. To resolve these issues, we introduce Narrow Band Internet of Things (NB-IoT) technology into industrial networks to reduce transmission delays. Two challenges are addressed in this work: (1) the primary goal is to guarantee the schedulability of the system, so the controller must determine when NB-IoT nodes transmit to base stations; and (2) because communication through the base station is a paid service, the controller must minimize the use of NB-IoT slots. We resolve these issues via a scheduling analysis and transmission mode selection. In addition, we propose a Path Selection Algorithm (PSA) to improve the schedulability of the industrial system. Experiments indicate the effectiveness and efficacy of our approach.

Secret key establishment is a fundamental requirement for private communication between two wireless entities. An intriguing solution is to extract secret keys from the inherent randomness shared between them. Although several works have been done to extract secret keys from different kinds of mediums (e.g., RSSI, CSI, CIR), the efficiency and security problems are not fully solved. In this paper, we consider the problem of secret key establishment for wireless devices, and propose MAGIK, a secure and efficient scheme based on dynamic geoMAGnetic field in Indoor environment for Key establishment. We carefully study the feasibility of utilizing indoor geomagnetic field for key extraction through extensive measurements. Our results demonstrate that geomagnetic field has several dynamic properties, including space-varying, time-varying, sensitive to measurement device, and correlative between two observed points in proximity. We also optimize the key extraction process and present two rotation-angle-based quantification methods, which can achieve faster key generation rates and lower bit mismatching ratios. Besides, we build a prototype on commodity mobile devices, and evaluate its performance by conducting real-word experiments in indoor scenarios. The experiment results confirm that our system is efficient, in terms of key extraction rate, and robust in secret key establishment without requiring additional overhead on mobile devices.

As the growing demand for the large-scale and diverse services, Device-to-Device (D2D) communications have been considered as one of the most promising methods in 5G to improve the capacity of the service network and the quality of experience (QoE) for mobile users, especially those located in specific areas, asking for the same kind of multimedia services. However, it is still tough for service providers to manage these devices in a short time because different users have different QoE requirements and the arrival and departure of each user are random, which severely affect the continuity of service for other neighbor users. In this paper, we propose a fast D2D Multimedia Transmission Scheme (named DMaster) based on local search to overcome these drawbacks and solve the D2D service initialization problem, which is NP-Complete. DMaster organizes D2D communications as a spanning tree transmitting SVC-based Adaptive Streaming (SVC-AS). Furthermore, we prove that the running time of DMaster utilizing disjoint-set is O(|L||D|α(|L|, |D|)), where L is the set of potential D2D links, D is the set of devices, and α is the inverse Ackerman function. Extensive simulations show that the proposed scheme guarantees QoE, fairness, and continuity of service and supports a large number of users. To the best of our knowledge, it is the first work focusing on the SVC-based fast service scheme in D2D communications.

Millimeter-wave (mmWave) communication is the rising technology for next-generation wireless transmission. Benefited by its abundant bandwidth and short wavelength, mmWave is advanced in multi-gigabit transmittability and beamforming. In contrast, the short wavelength also makes mmWave easily blocked by obstacles. In order to bypass these obstacles, relays are widely needed in mmWave communications. Unmanned autonomous vehicles (UAVs), such as drones and self-driving robots, enable the mobile relays in real applications. Nevertheless, it is challenging for a UAV to find its optimal relay location automatically. On the one hand, it is difficult to find the location accurately due to the complex and dynamic wireless environment; on the other hand, most applications require the relay to forward data immediately, so the autonomous process should be fast. To tackle this challenge, we propose a novel method AutoRelay specialized for mmWave communications. In AutoRelay, the UAV samples the link qualities of mmWave beams while moving. Based on the real-time sampling, the UAV gradually adjusts its path to approach the optimal location by leveraging compressive sensing theory to estimate the link qualities in candidate space, which increases the accuracy and save the time. Performance results demonstrate that AutoRelay outperforms existing methods in achieving an accurate and efficient relay strategy.

A smart factory generates vast amounts of data that require transmission via large-scale wireless networks. Thus, the reliability and real-time performance of large-scale wireless networks are essential for industrial production. A distributed data transmission scheme is suitable for large-scale networks, but is incapable of optimizing performance. By contrast, a centralized scheme relies on knowledge of global information and is hindered by scalability issues. To overcome these limitations, a hybrid scheme is needed. We propose a hierarchical data transmission framework that integrates the advantages of these schemes and makes a tradeoff among real-time performance, reliability, and scalability. The top level performs coarse-grained management to improve scalability and reliability by coordinating communication resources among subnetworks. The bottom level performs fine-grained management in each subnetwork, for which we propose an intrasubnetwork centralized scheduling algorithm to schedule periodic and aperiodic flows. We conduct both extensive simulations and realistic testbed experiments. The results indicate that our method has better schedulability and reduces packet loss by up to $22\%$ relative to existing methods.

Real-time abnormal driving behaviors monitoring is a corner stone to improving driving safety. Existing works on driving behaviors monitoring using smartphones only provide a coarse-grained result, i.e., distinguishing abnormal driving behaviors from normal ones. To improve drivers’ awareness of their driving habits so as to prevent potential car accidents, we need to consider a fine-grained monitoring approach, which not only detects abnormal driving behaviors but also identifies specific types of abnormal driving behaviors, i.e.,Weaving,Swerving,Sideslipping,Fast U-turn,Turning with a wide radius, andSudden braking. Through empirical studies of the 6-month driving traces collected from real driving environments, we find that all of the six types of driving behaviors have their unique patterns on acceleration and orientation. Recognizing this observation, we further propose a fine-grained abnormalDriving behaviorDetection and iDentification system,$D^{3}$, to perform real-time high-accurate abnormal driving behaviors monitoring using smartphone sensors. We extract effective features to capture the patterns of abnormal driving behaviors. After that, two machine learning methods,Support Vector Machine(SVM) andNeuron Networks(NN), are employed, respectively, to train the features and output a classifier model which conducts fine-grained abnormal driving behaviors detection and identification. From results of extensive experiments with 20 volunteers driving for another four months in real driving environments, we show that$D^{3}$achieves an average total accuracy of 95.36 percent with SVM classifier model, and 96.88 percent with NN classifier model.

In most existing cloud services, a centralized controller is used for resource management and coordination. However, such infrastructure is gradually not sufficient to meet the rapid growth of mega data centers. In recent literature, a new approach named devolved controller was proposed for scalability concern. This approach splits the whole network into several regions, each with one controller to monitor and reroute a portion of the flows. This technique alleviates the problem of an overloaded single controller, but brings other problems such as unbalanced work load among controllers and reconfiguration complexities. In this paper, we make an exploration on the usage of devolved controllers for mega data centers, and design some new schemes to overcome these shortcomings and improve the performance of the system. We first formulate Load Balancing problem for Devolved Controllers (LBDC) in data centers, and prove that it is NP-complete. We then design an f-approximation for LBDC, where f is the largest number of potential controllers for a switch in the network. Furthermore, we propose both centralized and distributed greedy approaches to solve the LBDC problem effectively. The numerical results validate the efficiency of our schemes, which can become a solution to monitoring, managing, and coordinating mega data centers with multiple controllers working together.

Wearable devices with various sensors are useful instruments to monitor human health. Due to the limited size, these wearable devices, however, always encounter critical energy problem, which further hinders their widely application. Considering that wireless communication dominates the total energy consumption, we make an in-depth study on the problem of communication energy consumption in body sensor networks. We first observe that the communication signals from wearable devices have strong correlation with human movements. Based on this correlation, we propose a Movement-based Adaptive Prediction Mechanism (MAPM). Specifically, we exploit Gaussian process regression to precisely fit and predict the transmission power combined with the characteristics of human movements. This prediction enables transmitters to automatically control their transmission power without feedback. Through simulation, we demonstrate that MAPM can save more than 40% energy compared to the sate-of-the-art methods.

A well-designed energy-efficient routing protocol is an indispensable part for prolonging the lifetime of wireless sensor networks (WSNs) because a sensor node usually has limited energy. Many research efforts are contributed on routing design in WSNs. With the development of green technology, the energy harvesting technique is being applied to real WSNs. Therefore, existing routing protocols are not suitable for such new WSNs with energy harvesting. In this paper, we concentrate on designing a novel routing protocol, named energy harvesting routing (EHR), which takes energy harvesting as one major factor into routing design to improve the energy efficiency. First, we introduce a hybrid routing metric combining the effect of residual energy and energy harvesting rate. Then we propose an updating mechanism allowing every node to maintain dynamic energy information of its neighbors. Based on the hybrid metric and the neighbor information, EHR is able to locally select the optimal next hop. Extensive simulations are conducted to evaluate the performance of EHR. Results demonstrate that EHR outperforms existing routing protocols in energy harvesting WSNs in term of the energy efficiency.

With the development of wireless communication and social network, wireless network service demands have increased rapidly in recent years. To amplify the wireless signals and expand the coverage of wireless networks, wireless relay nodes are introduced. This paper addresses the problem of finding an optimal deployment of access points and wireless relay nodes in an arbitrary environment to provide all the potential users with higher quality wireless network services. Our ambition is to maximize the coverage rate and to minimize the energy consumption of the relay nodes. Correspondingly, we design a scheme named OR-Play: an optimal relay placement scheme to provide high-quality wireless services, which consists of three phases. First, OR-Play provides an area coverage for an arbitrary area. We use the virtual force model to determine the positions of wireless devices, including access points and relay nodes, and thus extend the network lifetime. In the second phase, OR-Play selects access points by a 2-approximation algorithm for the metric k-center problem. In the third phase, we define a new problem: k-minimum energy broadcasting trees. We design a distributed greedy strategy to determine the broadcasting trees, based on which the power of relay nodes are precisely assigned. Finally, the simulation results validate the effectiveness and efficiency of OR-Play.

In the wireless communication, there are many cases where the transmission path is obstructed by unknown objects. With the rapid development of the drone technology in recent years, the drones are advocated to serve as mobile relays to forward data streams. However, the challenges are that data transmission may suffer severe signal attenuation due to the existence of the obstructions and it is challenging to find the best location for mobile relays due to the dynamic environment and unpredictable interference. To address the problem, this paper proposes an approach that a drone can automatically find the location with the optimal link quality. We design a novel algorithm, named Path-sampling Online Tensor Update (POTU), to estimate the link quality in the space and find the optimal location. Furthermore, the algorithm is practical to the real applications due to the simplicity of implementation. In the experiment, we construct a realistic scene and compare the performance of our algorithm with the classic and the state-of-the-art algorithms. As a result, POTU outperforms existing methods in achieving the trade-off between time cost and estimation accuracy.

The connected vehicles have been considered as a remedy for modern traffic issues, potentially saving hundreds of thousands of lives every year worldwide. The Dedicated Short-Range Communications (DSRC) technology is an essential building block of this promising vision. DSRC faces volatile vehicular environments, where not only wireless propagation channels but also network topologies vary rapidly. Moreover, traffic congestions during rush hours may lead to an unprecedentedly high density of broadcasting radios, resulting in compromised reliability, efficiency and fairness of DSRC. In order to optimize the performance of DSRC, we develop a novel Online Control Approach of power and Rates (OnCAR). Supported by systematic control theories, OnCAR performs stably even in the dynamic and unpredictable vehicular environments. To the best of our knowledge, OnCAR is the first solution to address the strong coupling between communication variables. It adopts a multi-variable control model to synchronously adjust transmission power and data rates, which are two major variables determining the performance of DSRC. In addition, OnCAR leverages receiver-side measurements of performance metrics to strike a balance between overall performance and fairness. Compared with the state of the art, OnCAR enhances the overall reliability and efficiency of DSRC by 23.7% and 30.1%, respectively. Meanwhile, these numbers are achieved with a 40.1% improvement in fairness.

Mobile crowdsensing has become a novel and promising paradigm in collecting environmental data. A critical problem in improving the QoS of crowdsensing is to decide which users to select to perform sensing tasks, in order to obtain the most informative data, while maintaining the total sensing costs below a given budget. The key challenges lie in (i) finding an effective measure of the informativeness of users' data, (ii) learning users' sensing costs which are unknown a priori, and (iii) designing efficient user selection algorithms that achieve low-regret guarantees. In this paper, we build Gaussian Processes (GPs) to model spatial locations, and provide a mutual information-based criteria to characterize users' informativeness. To tackle the second and third challenges, we model the problem as a budgeted multi-armed bandit (MAB) problem based on stochastic assumptions, and propose an algorithm with theoretically proven low-regret guarantee. Our theoretical analysis and evaluation results both demonstrate that our algorithm can efficiently select most informative users under stringent constraints.

The increasing market share of electric vehicles (EVs) makes charging facilities indispensable infrastructure for integrating EVs into the future intelligent transportation systems and smart grid. One promising facility called fast charging reservation(FCR) system was recently proposed. It allows people to reserve fast chargers ahead of time. In this system, fast chargers are the most scarce resource instead of electricity. Thus how to allocate these charging points requires careful designing. A good allocation policy should 1) ensure charging points to be allocated to EV users who really value them, and 2) prevent users' private information, e.g., identity, personal agenda, residing area and etc., from being inferred. A simple combination of classic multi-item auction and user identity anonymization cannot satisfy both criteria simultaneously. To find such an allocation, in this paper we investigate the design of privacy-preserving auctions in FCR systems. Traditional privacy-preserving strategies such as cryptography could incur high computation and communication overhead and hence jeopardize the efficiency of allocation. To this end, we propose Auc2Reserve, a differentially private randomized auction. Auc2Reserve applies an improved approximate sampler and the belief propagation (BP) technique to accelerate the resource allocation and pricing process. As a result, it is much more computationally efficient than generic exponential differentially private mechanisms and other theoretical approximate implementations. Through theoretical analysis, we show that Auc2Reserve is ?-incentive compatible, individual rational and ?-differentially private. And it provides a close-form approximation ratio in social welfare of FCR systems. In addition, we also demonstrate the efficacy of Auc2Reserve in terms of social welfare and privacy leakage via numerical simulation.

Large-scale charging stations become indispensable infrastructure to support the rapid proliferation of electric vehicles. Their operation modes have drawn great attention from both academia and industry. One promising mode called park-and-charge has been recently introduced. This new mode allows customers to park their electric vehicles at a parking lot, where the vehicles are charged during the parking time. Several small-scale experiments, such as the V-Charge project and General Motors' E-Motor plant, have demonstrated its potential. A key enabler for deploying this mode to large-scale stations is effective and efficient charging load scheduling methods. Most existing works confine to the time-driven scheduling policy due to their sole focus on the charging service. Applying their solutions to the park-and-charge mode would jeopardize the unitization of charging resource or cause frequent charging mode switching. This inapplicability motivates us to explore the feasibility and benefits of exploiting the event-driven scheduling policy in park-and-charge systems. Further, to better characterize charging load in this mode, we propose to adopt a metered model, by which a system gains value in proportion to the served charging demand. To be specific, the objective of this paper is to carry out both theoretical and experimental analysis for event-driven algorithms adapted to this metered model. We leverage both the competitive analysis and resource augmentation to demonstrate the non-constant and constant performance bounds for the earliest-deadline-first and highest-value-first algorithms respectively. Moreover, we provide a stronger theoretical result, i.e., the performance bound for the whole class of work-conserving scheduling algorithms. Through extensive simulations, we validate the proposed theoretical results and further provide interesting findings from the in-depth analysis of the simulation results.

In Intelligent Transport field, the Public Vehicle System is proposed to introduce a concept of a specialized vehicle for public transportation, which can integrate and substitute for vehicles such as taxis, buses and railways. Public Vehicle model has several advantages over earlier models, but the algorithm proposed in the model can't consider all potential solutions when building new paths, resulting in a decrease in performance. We expand the searching method to cover all cases of insertion and achieve a lower cost. Our simulations show that the Combinatorial Insertion Algorithm can have a 5%-11% promotion in total traveling distance.

Exploration of white spaces has been recognized as a promising way to improve the utilization of wireless spectrums. Especially, indoor white space exploration has been shown to be much more challenging than that in outdoor environment. Most of existing works on indoor white space exploration infer availabilities of TV channels based on the correlations among the channels and locations, which is learned from the training data measured beforehand. However, the process of training data collection normally requires considerable time and devices, as well as human power. In this paper, we perform a measurement of indoor white spaces and study their characteristics. Based on the in-depth understanding of the characteristics, we propose a Training-free Indoor white space exploration MEchanism (TIME). In TIME, we design an algorithm for channel state inference based on Bayesian compressive sensing, as well as an incremental method for deployment of spectrum detectors. Furthermore, we present an algorithm to determine a proper number of spectrum detectors in need. Extensive real-world experiments are conducted to evaluate TIME's performance. The evaluation results demonstrate that TIME achieves competitive performances against the state-of-the-art training-based mechanisms.

Substantial technology advances have been made in areas of autonomous and connected vehicles, which opens a wide landscape for future transportation systems. We propose a new type of transportation system, Public Vehicle (PV) system, to provide effective, comfortable, and convenient service. The PV system is to improve the efficiency of current transportation systems, \eg, taxi system. Meanwhile, the design of such a system targets on significant reduction in energy consumption, traffic congestion, and provides solutions with affordable cost. The key issue of implementing an effective PV system is to design efficient scheduling algorithms. We formulate it as the PV Path (PVP) problem, and prove it is NP-Complete. Then we introduce a real time approach, which is based on solutions of the Traveling Salesman Problem (TSP) and it can serve people efficiently with lower costs. Our results show that to achieve the same performance (e.g., the total time: waiting and travel time), the number of vehicles can be reduced by 47%-69%, compared with taxis. The number of vehicles on roads is reduced, thus traffic congestion is relieved.

Location based services have experienced an explosive growth and evolved from utilizing a single location to the whole trajectory. Due to the hardware and energy constraints, there are usually many missing data within a trajectory. In order to accurately recover the complete trajectory, crowdsensing provides a promising method. This method resorts to the correlation among multiple users' trajectories and the advanced compressive sensing technique, which significantly outperforms conventional interpolation methods on accuracy. However, as trajectories exposes users' daily activities, the privacy issue is a major concern in crowdsensing. While existing solutions independently tackle the accurate trajectory recovery and privacy issues, yet no single design is able to address these two challenges simultaneously. Therefore in this paper, we propose a novel Privacy Preserving Compressive Sensing (PPCS) scheme, which encrypts a trajectory with several other trajectories while maintaining the homomorphic obfuscation property for compressive sensing. Under PPCS, adversaries can only capture the encrypted data, so the user privacy is preserved. Furthermore, the homomorphic obfuscation property guarantees that the recovery accuracy of PPCS is comparable to the state-of-the-art compressive sensing design. Based on two publicly available traces with numerous users and long durations, we conduct extensive simulations to evaluate PPCS. The results demonstrate that PPCS achieves a high accuracy of9,000 m even when up to 50% original data are missing.

Vehicle-to-vehicle safety data dissemination plays an increasingly important role in ensuring the safety and efficiency of vehicle transportation. When collecting safety data, vehicles always prefer data generated at a closer location over data generated at a distant location, and prefer recent data over outdated data. However, these data preferences have been overlooked in most of existing safety data dissemination protocols, preventing vehicles getting more precise traffic information. In this paper, we explore the feasibility and benefits of incorporating the data preferences of vehicles in designing efficient safety data dissemination protocols. In particular, we propose the concept of packet-value to quantify these data preferences. We then design PVCast, a packet-value-based safety data dissemination protocol in VANET. PVCast makes the dissemination decision for each packet based on its packet-value and effective dissemination coverage in order to satisfy the data preferences of all the vehicles in the network. In addition, PVCast is lightweight and fully distributed. We evaluate the performance of PVCast on the ns-2 platform by comparing it with three representative data dissemination protocols. Simulation results in a typical highway scenario show that PVCast provides a significant improvement on per-vehicle throughput, per-packet dissemination coverage with small per-packet delay. Our findings demonstrate the importance and necessity of comprehensively considering the data preferences of vehicles when designing an efficient safety data dissemination protocol for VANET.

Participatory sensing enables to collect a vast amount of data from the crowd by allowing a wide variety of sources to contribute data. However, the openness of participatory sensing exposes the system to malicious and erroneous participations, inevitably resulting in poor data quality. This brings forth the important issues of false data detection and correction in participatory sensing. Furthermore, data collected by participants normally include considerable missing values, which poses challenges for accurate false data detection. In this work, we propose DECO, a general framework to detect false values for participatory sensing in the presence of missing data. By applying a tailored spatio-temporal compressive sensing technique, DECO is able to accurately detect the false data and estimate both false and missing values for data correction. We validate our design through an experimental case study.

This paper presents mZig, a novel physical layer design that enables a receiver to simultaneously decode multiple packets from different transmitters in ZigBee. As a low-power and low-cost wireless protocol, the promising ZigBee has been widely used in sensor networks, cyber-physical systems, and smart buildings. Since ZigBee based networks usually adopt tree or cluster topology, the convergecast scenarios are common in which multiple transmitters need to send packets to one receiver. For example, in a smart home, all appliances report data to one control plane via ZigBee. However, concurrent transmissions in convergecast lead to the severe collision problem. The conventional ZigBee avoids collisions using backoff time, which introduces additional time overhead. Advanced methods resolve collisions instead of avoidance, in which the state-of-the-art ZigZag resolves one m-packet collision requiring m retransmissions. We propose mZig to resolve one m-packet collision by this collision itself, so the theoretical throughput is improved m-fold. Leveraging the unique features in ZigBee's physical layer including its chip rate, half-sine pulse shaping and O-QPSK modulation, mZig subtly decomposes multiple packets from one collision in baseband signal processing. The practical factors of noise, multipath, and frequency offset are taken into account in mZig design. We implement mZig on USRPs and establish a seven-node testbed. Experiment results demonstrate that mZig can receive up to four concurrent packets in our testbed. The throughput of mZig is 4.5x of the conventional ZigBee and 3.2x of ZigZag in the convergecast with four or more transmitters.

In this paper, we present a novel Frequency-divided Instantaneous Neighbors Estimation (FINE) system specifically designed for density estimation in Dedicated Short Range Communication (DSRC) based vehicular networks. A large amount of vehicular applications such as navigation, traffic control, and data dissemination substantially rely on the density information. Recent works pay great attention to obtain the real-time density information and reduce the occupation time of DSRC channel. The state-of-the-art approach is the Framed Slotted ALOHA (FSA) framework, which benefits from its fine-grained time division design. However, FSA considers only time resource and is unaware of the frequency resource in DSRC. For further accelerating the density acquisition, we propose a frequency-divided approach. The core idea of FINE is to resort fine-grained channel division for parallel neighbors counting. Extensive simulations are conducted to evaluate FINE. The results demonstrate that FINE significantly outperforms existing methods. In a typical dense scenario, FINE reduces the time cost from 2 ms (FSA) to 50 μs, while maintains the accuracy at the same level as FSA.

Environment reconstruction is to rebuild the physical environment in the cyberspace using the sensory data collected by sensor networks, which is a fundamental method for human to understand the physical world in depth. A lot of basic scientific work such as nature discovery and organic evolution heavily relies on the environment reconstruction. However, gathering large amount of environmental data costs huge energy and storage space. The shortage of energy and storage resources has become a major problem in sensor networks for environment reconstruction applications. Motivated by exploiting the inherent feature of environmental data, in this paper, we design a novel data gathering protocol based on compressive sensing theory and time series analysis to further improve the resource efficiency. This protocol adapts the duty cycle and sensing probability of every sensor node according to the dynamic environment, which cannot only guarantee the reconstruction accuracy, but also save energy and storage resources. We implement the proposed protocol on a 51-node testbed and conduct the simulations based on three real datasets from Intel Indoor, GreenOrbs and Ocean Sense projects. Both the experiment and simulation performances demonstrate that our method significantly outperforms the conventional methods in terms of resource efficiency and reconstruction accuracy.

Recently, adopting mobile energy chargers to replenish the energy supply of sensor nodes in wireless sensor networks has gained increasing attention from the research community. Different from energy harvesting systems, the utilization of mobile energy chargers is able to provide more reliable energy supply than the dynamic energy harvested from the surrounding environment. While pioneering works on the mobile recharging problem mainly focus on the optimal offline path planning for the mobile chargers, in this work, we aim to lay the theoretical foundation for the on-demand mobile charging (DMC) problem, where individual sensor nodes request charging from the mobile charger when their energy runs low. Specifically, in this work, we analyze the on-demand mobile charging problem using a simple but efficient Nearest-Job-Next with Preemption (NJNP) discipline for the mobile charger, and provide analytical results on the system throughput and charging latency from the perspectives of the mobile charger and individual sensor nodes, respectively. To demonstrate how the actual system design can benefit from our analytical results, we present two examples on determining the essential system parameters such as the optimal remaining energy level for individual sensor nodes to send out their recharging requests and the minimal energy capacity required for the mobile charger. Through extensive simulation with real-world system settings, we verify that our analytical results match the simulation results well and the system designs based on our analysis are effective.

Data collection is a crucial operation in wireless sensor networks. The design of data collection schemes is challenging due to the limited energy supply and the hot spot problem. Leveraging empirical observations that sensory data possess strong spatiotemporal compressibility, this paper proposes a novel compressive data collection scheme for wireless sensor networks. We adopt a power-law decaying data model verified by real data sets and then propose a random projection-based estimation algorithm for this data model. Our scheme requires fewer compressed measurements, thus greatly reduces the energy consumption. It allows simple routing strategy without much computation and control overheads, which leads to strong robustness in practical applications. Analytically, we prove that it achieves the optimal estimation error bound. Evaluations on real data sets (from the GreenOrbs, IntelLab and NBDC-CTD projects) show that compared with existing approaches, this new scheme prolongs the network lifetime by 1.5X to 2X for estimation error 5-20 percent.

Nowadays, RFID systems have been widely deployed for applications such as supply chain management and inventory control. One of their most essential operations is to swiftly identify individual tags to distinguish their associated objects. Most existing solutions identify tags sequentially in the temporal dimension to avoid signal collisions, whose performance degrades significantly as the system scale increases. In this paper, we propose aParallel Identification Protocol(PIP) for RFID systems, which achieves the parallel identification paradigm and is compatible with current RFID devices. Uniquely, PIP encodes the tag ID into a specially designed pattern and thus greatly facilitates the reader to correctly and effectively recover them from collisions. Furthermore, we analytically investigate its performance and provide guidance on determining its optimal settings. Extensive simulations show that PIP reduces the identification delay by about 25%-50% when compared with the standard method in EPC C1G2 and the state-of-the-art solutions.

Smartphones and mobile devices have greatly penetrated the daily lives of many people. While participatory/pervasive sensing has gained wide adoptions by leveraging various onboard sensors on mobile devices, another powerful resource, the computational power on these mobile devices has been less frequently harnessed by researchers and practitioners. To fill this gap, we propose in this work the modeling, analysis, and implementation of participatory computing. Specifically, we propose REPC, a generic randomized task assignment framework for the participatory computing paradigm, which guarantees the overall system performance with close to minimal workload at individual participating devices. To achieve these design objectives, we model the intrinsic relationship between the workload of individual devices and the probability they complete their assigned tasks. Based on our modeling results, we analyze the maximal system capacity for any given participatory computing system and derive the minimal workload for individual participating devices to achieve the overall system performance requirement. We have fully implemented our design on the Android platform and demonstrated its performance through a representative participatory computing application. Extensive experiments and simulation results demonstrate that our design is able to achieve more than 90% task completion ratios with only 10% system overhead in practice.

The data gathering is a fundamental operation in wireless sensor networks. Among approaches of the data gathering, the compressive data gathering (CDG) is an effective solution, which exploits the spatiotemporal correlation of raw sensory data. However, in the multi-attribute scenario, the performance of CDG decreases in every attribute's capacity because more measurements are on demand. In this paper, under the general framework of CDG, we propose a multi-attribute compressive data gathering protocol, taking into account the observed interattribute correlation in the multi-attribute scenario. Firstly, we find that 1) the rapid growth of the demand on measurements may decline the network capacity, 2) according to the compressive sensing theory, correlations among attributes can be utilized to reduce the demand on measurements without the loss of accuracy, and 3) such correlations can be found on real data sets. Secondly, motivated by these observations, we propose our approach to decline measurements. Finally, the real-trace simulation shows that our approach outperforms the original CDG under multiattribute scenario. Compared to the CDG, our approach can save 16% demand on measurements.

Electric vehicle (EV) is a promising transportation with plenty of advantages, e.g., low carbon emission, high energy efficiency. However, it requires frequent and long time charging. In public charging stations, EVs spend long time on queuing especially during peak hours. Hence, it requires an efficient method to reduce the total charging time for EVs. We study the Electric Vehicle Charging-Scheduling (EVCS) problem in this paper. First we prove that EVCS is NP-Complete, which can be reduced from one Parallel Machine Scheduling (PMS) problem. Then two heuristic algorithms are proposed: the Earliest Start Time (EST) algorithm, and the Earliest Finish Time (EFT) algorithm. EST tries to advance the start charging time to get customers in service as early as possible, while EFT focuses on the possible finish charging time to get customers served as soon as possible. Finally simulations show that, the proposed algorithms outperform the classic greedy nearest scheduling algorithm: assign each EV to its nearest charging station, then choose the outlet where the fewest EVs are queuing. Typically, under our simulation settings, the average finish time and maximum finish time can be reduced by about one hour, and six hours respectively.

Reconstructing the environment by sensory data is a fundamental operation for understanding the physical world in depth. A lot of basic scientific work (e.g., nature discovery, organic evolution) heavily relies on the accuracy of environment reconstruction. However, data loss in wireless sensor networks is common and has its special patterns due to noise, collision, unreliable link, and unexpected damage, which greatly reduces the reconstruction accuracy. Existing interpolation methods do not consider these patterns and thus fail to provide a satisfactory accuracy when the missing data rate becomes large. To address this problem, this paper proposes a novel approach based on compressive sensing to reconstruct the massive missing data. Firstly, we analyze the real sensory data from Intel Indoor, GreenOrbs, and Ocean Sense projects. They all exhibit the features of low-rank structure, spatial similarity, temporal stability and multi-attribute correlation. Motivated by these observations, we then develop an environmental space time improved compressive sensing (ESTI-CS) algorithm with a multi-attribute assistant (MAA) component for data reconstruction. Finally, extensive simulation results on real sensory datasets show that the proposed approach significantly outperforms existing solutions in terms of reconstruction accuracy.

Coverage is a fundamental problem in wireless sensor networks (WSNs). Conventional studies on this topic focus on 2D ideal plane coverage and 3D full space coverage. The 3D surface of a field of interest (FoI) is complex in many real-world applications. However, existing coverage studies do not produce practical results. In this paper, we propose a new coverage model called surface coverage. In surface coverage, the field of interest is a complex surface in 3D space and sensors can be deployed only on the surface. We show that existing 2D plane coverage is merely a special case of surface coverage. Simulations point out that existing sensor deployment schemes for a 2D plane cannot be directly applied to surface coverage cases. Thus, we target two problems assuming cases of surface coverage to be true. One, under stochastic deployment, what is the expected coverage ratio when a number of sensors are adopted? Two, if sensor deployment can be planned, what is the optimal deployment strategy with guaranteed full coverage with the least number of sensors? We show that the latter problem is NP-complete and propose three approximation algorithms. We further prove that these algorithms have a provable approximation ratio. We also conduct extensive simulations to evaluate the performance of the proposed algorithms.

In wireless sensor networks (WSNs), since many basic scientific works heavily rely on the complete sensory data, data recovery is an indispensable operation against the data loss. Several works have studied the missing value problem. However, existing solutions cannot achieve satisfactory accuracy due to special loss patterns and high loss rates in WSNs. In this work, we propose a multiple attributes-based recovery algorithm which can provide high accuracy. Firstly, based on two real datasets, the Intel Indoor project and the GreenOrbs project, we reveal that such correlations are strong, e.g., the change of temperature and light illumination usually has strong correlation. Secondly, motivated by this observation, we develop a Multi-Attribute-assistant Compressive-Sensing-based (MACS) algorithm to optimize the recovery accuracy. Finally, real trace-driven simulation is performed. The results show that MACS outperforms the existing solutions. Typically, MACS can recover all data with less than 5% error when the loss rate is less than 60%. Even when losing 85% data, all missing data can be estimated by MACS with less than 10% error.

Recent advances in wireless communication and electronic manufacture have enabled a variety of sensors to be used for Wireless Body Area Networks (WBANs), which can provide real-time body monitoring and feedback for enabling patient diagnostics procedure, rehabilitation, sports training and interactive performance. However, existing single-hop wireless communication scheme faces several major challenges: rapid growth of channel conflicts as more sensors added, impermeability of human body to radio waves and highly dynamic network topology due to human movements. In this paper, a prototype of multi-hop WBAN has been built to quantify the channel conflict and to characterise the network connectivity during human motions. A probability based routing protocol fusing inertial sensor data and history link quality is then developed, which aims at capturing the high spatio-temporal change of network topology on the selection of a reliable relay node in WBAN routing. The performance of the protocol is experimentally evaluated on our prototype system. Compared with a number of existing routings, the proposed scheme is more splendid in terms of average delivery ratio, number of hops and end-to-end delay.

Reconstructing the environment in cyber space by sensory data is a fundamental operation for understanding the physical world in depth. A lot of basic scientific work (e.g., nature discovery, organic evolution) heavily relies on the accuracy of environment reconstruction. However, data loss in wireless sensor networks is common and has its special patterns due to noise, collision, unreliable link, and unexpected damage, which greatly reduces the accuracy of reconstruction. Existing interpolation methods do not consider these patterns and thus fail to provide a satisfactory accuracy when missing data become large. To address this problem, this paper proposes a novel approach based on compressive sensing to reconstruct the massive missing data. Firstly, we analyze the real sensory data from Intel Indoor, GreenOrbs, and Ocean Sense projects. They all exhibit the features of spatial correlation, temporal stability and low-rank structure. Motivated by these observations, we then develop an environmental space time improved compressive sensing (ESTICS) algorithm to optimize the missing data estimation. Finally, the extensive experiments with real-world sensory data shows that the proposed approach significantly outperforms existing solutions in terms of reconstruction accuracy. Typically, ESTICS can successfully reconstruct the environment with less than 20% error in face of 90% missing data.

Large-scale battery packs with hundreds/thousands of battery cells are commonly adopted in many emerging cyber-physical systems such as electric vehicles and smart micro-grids. For many applications, the load requirements on the battery systems are dynamic and could significantly change over time. How to resolve the discrepancies between the output power supplied by the battery system and the input power required by the loads is key to the development of large-scale battery systems. Traditionally, voltage regulators are often adopted to convert the voltage outputs to match loads' required input power. Unfortunately, the efficiency of utilizing such voltage regulators degrades significantly when the difference between supplied and required voltages becomes large or the load becomes light. In this paper, we propose to address this problem via an adaptive reconfiguration framework for the battery system. By abstracting the battery system into a graph representation, we develop two adaptive reconfiguration algorithms to identify the desired system configurations dynamically in accordance with real-time load requirements. We extensively evaluate our design with empirical experiments on a prototype battery system, electric vehicle driving trace-based emulation, and battery discharge trace-based simulations. The evaluation results demonstrate that, depending on the system states, our proposed adaptive reconfiguration algorithms are able to achieve 1× to 5× performance improvement with regard to the system operation time.

An urban vehicular network is a typical type of Delay Tolerant Network (DTN). Based on the routing analysis in a DTN, we first put forward a Minimum Delay and Hop Algorithm (MDHA), which requires both historical and future information on all the vehicles in the network. Since MDHA is not practical, we then design a Traffic Aware Routing Algorithm (TARA), which uses the historical and the real-time vehicle information to make routing decisions on the road structure level. A simulation using real GPS data in Shanghai shows that TARA significantly reduces the transmission delay and the hop count compared to the traditional GEO routing and GPSR.

Data loss is ubiquitous in wireless sensor networks (WSNs) mainly due to the unreliable wireless transmission, which results in incomplete sensory data sets. However, the completeness of a data set directly determines its availability and usefulness. Thus, sensory data recovery is an indispensable operation against the data loss problem. However, existing solutions cannot achieve satisfactory accuracy due to special loss patterns and high loss rates in WSNs. In this work, we propose a novel sensory data recovery algorithm which exploits the spatial and temporal joint-sparse feature. Firstly, by mining two real datasets, namely the Intel Indoor project and the GreenOrbs project, we find that: (1) for one attribute, sensory readings at nearby nodes exhibit inter-node correlation; (2) for two attributes, sensory readings at the same node exhibit inter-attribute correlation; (3) these inter-node and inter-attribute correlations can be modeled as the spatial and temporal joint-sparse features, respectively. Secondly, motivated by these observations, we propose two Joint-Sparse Sensory Data Recovery (JSSDR) algorithms to promote the recovery accuracy. Finally, real data-based simulations show that JSSDR outperforms existing solutions. Typically, when the loss rate is less than 65%, JSSDR can estimate missing values with less than 10% error. And when the loss rate reaches as high as 80%, the missing values can be estimated by JSSDR with less than 20% error.

With recent progress in vehicle autonomous driving and vehicular communication technologies, vehicle systems are developing towards fully connected and fully autonomous systems. This paper studies lane assignment strategies for connected autonomous vehicles in a highway scenario and their impact on the overall traffic efficiency and safety. We formulate a model of connected autonomous vehicles, which includes three features: traffic data available online, ultra-short reaction time, and cooperative driving. Based on this model, we propose a novel lane change maneuver Politely Change Lane (PCL), which achieves the tradeoff between traffic safety and efficiency. Its effectiveness is validated and evaluated by extensive simulations. The performance shows that PCL improves both safety and efficiency of the overall traffic, especially with heavy traffic.

In most delay tolerant network (DTN) applications, mobile nodes utilize WiFi radios to obtain local information and transmit data. One bottleneck on DTN delivery performance is the short communication range of the WiFi radio. Rather than designing efficient protocols on WiFi based DTN, we propose a novel dual-radio architecture by adding a long-range low-bitrate eagle eye (EE) radio on every node. This EE radio can “see” real-time movement information of nodes in a significantly large range, and so much early scheduling can be done with this radio when compared with WiFi which is still in charge of data transmissions. Benefiting from this cooperative dual radios architecture, we design distributed EE routing protocol for minimizing delivery delay in DTNs. Through our prototype implementation with 7 EE devices and simulations based on real trace data of 4000 taxis in Shanghai, we show that the proposed architecture is able to achieve as low as 40% of the average delay with traditional DTNs.

This paper studies mobile barrier coverage (MBC) surrounding dynamic objects. In the real world, several dynamic objects can benefit from MBC. For example, marching troop can detect any adversary intrusion without blind spot by MBC. However, conventional works only focused on barrier coverage for static objects, which fail when the objects start to move. Issues to address these dynamic-object scenarios, we propose the problem of mobile barrier coverage for dynamic objects. The most challenge is how to effectively maintain MBC when the motion of objects are unpredictable. We propose a fully distributed algorithm for mobile sensor nodes to cooperatively move and maintain the high-quality barrier coverage. The extensive simulations based on large-scale trace data demonstrate the efficiency and efficacy of the proposed algorithm.

In sensor networks many efforts have been made on barrier coverage. Most of them rely on the assumption that sensors are randomly or manually deployed around the region of interest. It is obvious that the random deployment wastes many redundant sensors without contribution on the barrier formation. Moreover, in most real scenarios, it is difficult to deploy sensors manually due to the region usually in large scale or in danger. Hence, this paper studies the problem that using mobile sensors to form barrier surrounding the region automatically. The fundamental objective is to take full advantage of the limited number of mobile sensors to form the barrier coverage with the highest detection capability. The challenge is that the sensors only have local information. A fully distributed algorithm based on virtual force and convex analysis is developed for the objective to relocate the sensors from the original positions to uniformly distribute on the convex hull of the region. Simulation results verify the validity of our proposed cooperative scheme.

Cyber-physical systems (CPS) bridge the virtual cyber world with the real physical world. For representing a physical environment in cyber, CPS devices / nodes are assigned to collect data in a region of interest. In practice, the nodes seldom fully cover the region due to the restriction of quantity and cost. Hence, the sampled data are usually inadequate to describe the holistic environment. Recent researches mainly focus on the interpolation methods to generate an approximating model from the raw data. However, in this paper, we propose to study the spatio-temporal distribution of CPS nodes in order to obtain the crucial data for optimal environment abstraction. There are two target problems. First, when the environment changes little over time, what is the optimal spatial distribution of stationary nodes based on historical data? Second, when the environment is time-varying, what is the adaptive spatio-temporal distribution of mobile nodes? We show the NP hardness of the former problem and propose an approximation algorithm. For the latter problem, we develop a cooperative movement algorithm on nodes for achieving a curvature-weighted distribution pattern. A trace driven simulation based on real data of GreenOrbs project evaluates the performance of the proposed approaches.

Capacity is one fundamental problem in wireless Ad hoc networks. Deploying directional antennas to wireless networks can reduce interference among concurrent transmissions and increase spatial reuse, while the technology of multi-channel can separate concurrent transmissions. Therefore, combining these two technologies into one wireless network is capable of great improvement on the network capacity. Recent studies proposed a multi-channel network architecture that equips each wireless node with multiple directional antennas, which is called MC-MDA network. The capacity in MC-MDA network is derived under arbitrary and random placements. However, they only used a simplified directional antenna model. For approaching the more accurate capacity in real scenario, in this paper, we consider a hybrid antenna model, which takes the effect of side lobe and back lobe into account. We derive the capacity upper-bounds of MC-MDA networks in arbitrary and random network with the hybrid model to find the effect of back lobe and side lobe. We show that the network capacity is closely related to s the ratio of the radiuses of side lobe to main lobe. The capacity decreases when s increases. Moreover, we compare the network capacity of MC-MDA using the simplified antenna model with our results. When considering the factor of interference constraint, the capacity gain using the hybrid antenna model is √(θ2/θ2+(4π2-θ2)s) over the one with the simplified model.

Initialization is an indispensable process for wireless sensor networks since newly deployed sensors lack a reliable infrastructure for communication. Many efforts have been made to address the problem on initialization. However, most of them fall into the category of energy efficiency. In mission-critical scenarios, it is vital to reduce the initialization time in order to gather information as early as possible. In this paper, we study a new problem of accelerating initialization. First, we provide a novel parallel initialization mechanism that selects cluster heads before deployment and organizes single-hop clusters simultaneously after random deployment. Then, we prior-estimate that the number of cluster head candidates from n sensors is ¿(log n). Finally, simulation results show that these cluster head candidates can achieve the parallel initialization bounded by 16 time slots even for a large n.

We consider a practical application of intelligent vehicles for intersection traffic control. Specially, we study the intersection traffic control problem using reservation-based intersection traffic control system, which utilizes the information exchange between intelligent vehicles and management agents around the intersections to direct traffic, instead of traffic lights. We focus on how to design an effective passing permission (PP) allocation strategy for this system. In this work, with an observation that will cause this system to be inefficient, we propose a novel look-ahead passing permission allocation strategy (LICP) for intersection traffic control. The large-scale testing results show that LICP can make nearly 25% performance improvement on average intersection delay than the previous first come, first serve method (FCFS).