Inter-agent communication serves as an effective mechanism for enhancing performance in collaborative multi-agent reinforcement learning (MARL) systems. However, the inherent communication latency in practical systems induces both action decision delays and outdated information sharing, impeding MARL performance gains, particularly in time-critical applications like autonomous driving. In this work, we propose a Value-of-Information aware Low-latency Communication (VIL2C) scheme that proactively adjusts the latency distribution to mitigate its effects in MARL systems. Specifically, we define a Value of Information (VoI) metric to quantify the importance of delayed messages on the recipient agent's decision. We then design a VoI aware resource allocation method that dynamically prioritizes message transmission based on each delayed message's importance. Moreover, we propose a progressive message reception mechanism to adaptively adjust the reception duration based on received messages. We derive the optimized VoI aware resource allocation and theoretically prove the performance advantage of the proposed VIL2C scheme. Extensive experiments demonstrate that VIL2C outperforms existing approaches under various communication conditions. These gains are attributed to the low-latency transmission of high-VoI messages via resource allocation and the elimination of unnecessary waiting periods via adaptive reception duration.

Modern smart manufacturing pipelines have pervasively collaborated human workers, mobile robots, and industrial Internet of Things (IIoT) in shared workspaces for versatile production tasks. Despite the promising capacity of individual entities, the performance of these IIoT systems largely relies on pipeline coordination, i.e., task dispatching between humans and robots, which is particularly challenging under heterogeneous physical constraints and complex environmental uncertainties. Nonetheless, existing works either rely on traditional operation frameworks that lack scalability for large-scale complex production, or propose customized solutions for fixed agent models, overlooking the evolving nature of IIoT environments. To address these limitations, this paper proposes COACH, a human-robot collaborative manufacturing system that enables robust constraint-aware coordination across humans, robots, and IIoT. Specifically, COACH designs a scalable contextual encoder to represent the evolving relationships among human and robot agents in dynamic heterogeneous graphs. With that, a novel experience-driven task dispatcher is developed, enabling both high-performance and computation-efficient policy generation concerning the status of IIoT. To accommodate changing human fatigue and pipeline scales, COACH further develops a curriculum-enhanced reinforcement learning module for efficient dispatcher adaptation. Extensive evaluations using both synthetic testbeds and real-world manufacturing datasets demonstrate that COACH improves the feasible ratio of manufacturing pipelines by up to 27.4% and achieves up to 13.9% improvement in time efficiency compared to competing baselines across diverse job scales and environmental settings.

The proliferation of fake reviews, often produced by organized groups, undermines consumer trust and fair competition on online platforms. These groups employ sophisticated strategies that evade traditional detection methods, particularly in cold-start scenarios involving newly launched products with sparse data. To address this, we propose theDiversity- andSimilarity-awareDynamicGraphAttention-enhancedGraphConvolutionalNetwork (DS-DGA-GCN), a new graph learning model for detecting fake reviewer groups. DS-DGA-GCN achieves robust detection since it focuses on the joint relationships among products, reviews, and reviewers by modeling product-review-reviewer networks. DS-DGA-GCN also achieves adaptive detection by integrating a Network Feature Scoring (NFS) system and a new dynamic graph attention mechanism. The NFS system quantifies network attributes, including neighbor diversity, network self-similarity, as a unified feature score. The dynamic graph attention mechanism improves the adaptability and computational efficiency by captures features related to temporal information, node importance, and global network structure. Extensive experiments conducted on two real-world datasets derived from Amazon and Xiaohongshu demonstrate that DS-DGA-GCN significantly outperforms state-of-the-art baselines, achieving accuracies of up to89.8% and 88.3%, respectively.

Collaborative agents, consisting of at least one human and one mobile robot agent working toward a common objective, are increasingly prevalent and effective in both social and industrial spheres, such as manufacturing. The inherent heterogeneity of these agents requires efficient and scalable Task Scheduling and Allocation (TSA) schemes that match individuals to tasks based on their abilities and meet specific temporal constraints, maximizing performance in less time. Existing works face challenges as exact methods rely on assumptions and deterministic models, which struggle to scale and infer time-varying, stochastic human task performance. While offline reinforcement learning shows promise, it is time-consuming and heavily dependent on training data that is often scarce in practical factory settings. To address these challenges, we formulate the TSA problem in mobile multi-agent teams as a temporal-constrained contextual decision-making process and propose the Bayesian Optimization-augmented Team coordination among Heterogeneous agents (BOTH), a novel scalable and training-free scheduling approach. The core idea is to use Gaussian Processes (GP) to iteratively infer agent dynamics in real-time, enabling the automatic derivation of a robust TSA solution that requires no prior data and adapts to varying problem sizes. We start by employing a heterogeneous graph-based encoder to extract representative context from the individual differences among team agents and tasks, considering strict temporal constraints. Following this, we propose a GP-driven Bayesian optimizer to intelligently explore and exploit optimal task assignments for each context, without making assumptions about the system. Experiments on synthetic and real datasets demonstrate that BOTH boosts accuracy and time efficiency compared to competing baselines, even within a few iterations.

Continuous crowdsensing in Mobile CrowdSensing (MCS) involves ongoing monitoring to gather real-time data over extended periods. A key challenge is determining appropriate intervals between consecutive data samplings to capture temporal variations, especially in unknown dynamic environments. Traditional Age-of-Information (AoI) driven methods maintain data freshness but can be costly and result in data redundancy. To address this, we integrate the AoI metric with information entropy difference to create a novel indicator, Composite Data Value (CDV), balancing data freshness and redundancy. Based on it, we investigate the online adaptive sampling problem for continuous crowdsensing in unknown dynamic environments. This problem is challenging due to the vast space of sensing strategies, difficulty in estimating rewards with unknown distributions and varying rates of change, and the degradation of optimal strategies as the environment evolves. Using a multi-armed bandit framework, we propose AdaScs, an online adaptive sampling optimization approach to maximize long-term CDV performance. First, AdaScs develops compact sensing strategies through limited trials. Then, it adaptively performs online sampling based on evolving reward estimations, identifying optimal strategies, detecting environmental drifts, updating strategies, and adjusting cycle lengths. Our results show that AdaScs outperforms all baselines, with accuracy increasing by 22.6% and reaction time at last improving by 54.6%.

Vehicle edge computing can effectively ensure the quality of experience for user vehicles (UVs), but road side units (RSUs) with limited resources may not be able to handle intensive tasks under high traffic conditions. In this case, worker vehicles (WVs) with idle resources can share resources to alleviate the pressure on RSUs. However, selfish WVs may be reluctant to share idle computation resources without any rewards. In addition, the optimization problems in previous research are relatively simple and cannot be applied to complex scenarios. To address the above challenges, we propose an incentive-driven partial offloading framework aiming to maximize social welfare. In particular, the computing service provider (CSP) managing RSUs first determines resource prices and offloading rates with UVs, while also determining contract terms with WVs. Then, it generates the optimal task scheduling strategy and notifies the UVs to offload tasks to the corresponding WVs. Considering that maximizing social welfare is a mixed-integer nonlinear programming (MINLP) problem, we design the hybrid proximal policy optimization (HPPO)-based task offloading and resource allocation algorithm (HORA) with a hybrid action space to directly solve the original problem. Finally, extensive simulation results show that HORA outperforms other baseline methods across various scenarios, and the contract terms meet the constraints of individual rationality (IR) and incentive compatibility (IC).

While artificial intelligence (AI) technology has advanced in real-world applications, there is a strong motivation to develop hybrid systems where AI algorithms and humans collaborate, promoting more human-centered approaches in AI system design. This has led to the emergence of a novel human-machine computing (HMC) paradigm, which combines human cognitive abilities with machine computational power to create a collaborative computing framework that meets the demands of large-scale, complex tasks and enables human-machine symbiosis. Human processing units (HPUs) are crucial computing resources in HMC-oriented systems, and efficient HPU resource provisioning is key to boosting system performance. However, existing schemes often fail to assign tasks to the most suitable HPUs and optimize HPU utility, as they either cannot quantitatively measure skills or overlook utility concerns during task assignment and scheduling. To address these challenges, this article proposes a fine-grained HPU virtualization (FingHV) approach, which leverages virtualization techniques to improve flexibility, fairness, and utility in the provisioning process. The core idea is to use a tree-based skill model to precisely measure the levels and correlations of multiple skills within individual HPUs, and to apply a mixed time/event-based scheduling policy to maximize HPU utility. Specifically, we begin by proposing a hierarchical multiskill tree to model HPU skills and their correlations. Next, we formulate the HPU virtualization problem and present a fine-grained virtualization method, which includes a quality-driven HPU assignment process and a mixed time/event-based scheduling policy to improve resource-sharing efficiency. Finally, we evaluate FingHV on a synthetic dataset with varying task sizes and a real-world case. The results demonstrate that FingHV improves global matching quality by up to 39.7% and increases HPU utility by 11.2% compared to the baselines.

With the development of intelligent technology in coal mine industrial Internet of Things (IoT), the demand for salient object detection (SOD) in underground coal mine space has been increasing. The complex scenes and variable backgrounds in coal mine bring challenges for SOD, such as blurred edges, high computational complexity, and long processing times, making it difficult to meet the accuracy and real-time requirements of coal mine industrial IoT applications. To address these issues, we propose the dynamic weighting hybrid attention (DWHA)-partial convolution multiscale strip pooling (PCMSP) network for SOD in the coal mine industrial IoT. First, we introduce the DWHA module, which dynamically fuses self-attention for global context and SBAM for refining channel and spatial information, improving saliency detection accuracy. Second, we propose the PCMSP lightweight module, which the multiscale strip pooling introduces multiscale dilations, enhancing the ability to capture multiscale information and improve feature representation. By using partial convolution, which reduces the consumption of computing resources and running time while ensuring boundary quality. The experimental results indicate that, using self-built dataset for underground coal mine SOD, the DWHA-PCMSP network outperforms the four SOTA: BASNet, U2Net, SUCA, and EDN by achieving an increase of 2.82% in F1-score, a decrease of 23.70% in MAE, a reduction of 72.3G in FLOPs, and an improvement of 6.6 FPS in speed, compared to the worst-performing model.

Integrating Unmanned Aerial Vehicles (UAVs) and autonomous vehicles within the crowdsensing paradigm offers a promising approach to collecting environment-relevant data over large spatial areas, particularly in disaster-stricken or high-risk regions. However, deploying crowdsensing systems in emergency response scenarios presents substantial challenges. The lack of prior environmental knowledge complicates the selection of optimal sensing locations and strategy optimization, often relying on costly trial-and-error methods. Additionally, realtime decision-making is critical in such scenarios, requiring the rapid identification of optimal deployment strategies. Yet, the absence of prior knowledge further complicates the assessment of the optimality of these strategies. This gap remains inadequately addressed in existing research. To address this, we present the first framework that frames these challenges as a rapid online strategy optimization problem for mobile agent-based crowdsensing systems operating in unknown environments during emergency response scenarios. We propose DGap-UCB, a novel approach within the multi-armed bandit (MAB) framework, which efficiently identifies the optimal sensing strategy with highconfidence guarantees. Leveraging the Upper-Confidence Bound (UCB) technique, DGap-UCB iteratively refines strategy selection based on reward feedback. To accelerate learning, we introduce a gap-confidence pair (Δt, δt)-based Quick Stopping Criterion, enabling rapid and high-confidence identification of the optimal strategy. Extensive experiments on both synthetic and real-world datasets demonstrate the superiority of DGap-UCB over stateof-the-art techniques

Visual Simultaneous Localization and Mapping (vSLAM) is a prevailing technology for many emerging robotic applications. Achieving real-time SLAM on mobile robotic systems with limited computational resources is challenging because the complexity of SLAM algorithms increases over time. This restriction can be lifted by offloading computations to edge servers, forming the emerging paradigm ofedge-assisted SLAM. Nevertheless, the exogenous and stochastic input processes affect the dynamics of the edge-assisted SLAM system. Moreover, the requirements of clients on SLAM metrics change over time, exerting implicit and time-varying effects on the system. In this paper, we aim to push the limit beyond existing edge-assist SLAM by proposing a new architecture that can handle the input-driven processes and also satisfy clients’ implicit and time-varying requirements. The key innovations of our work involve a regional feature prediction method for importance-aware local data processing, a configuration adaptation policy that integrates data compression/decompression and task offloading, and an input-dependent learning framework for task scheduling with constraint satisfaction. Extensive experiments prove that our architecture improves pose estimation accuracy and saves up to 47% of communication costs compared with a popular edge-assisted SLAM system, as well as effectively satisfies the clients’ requirements.

Unmanned Aerial Vehicle (UAV)-assisted Mobile Edge Computing (MEC) has received extensive attention because it provides resilient computation services for multiple Mobile Users (MUs). However, due to the increasing scale of offloaded tasks, the uncertain mobility of MUs, and the limited energy budget of UAV and MUs, it is extremely challenging to achieve satisfactory Quality-of-Service (QoS). Non-Orthogonal Multiple Access (NOMA), a promising technology to serve multiple MUs with limited communication resources, has great potential to be integrated with MEC. To this end, this paper proposes a QoS-oriented NOMA-enhanced UAV-MEC system, which aims to capture the potential gains of uplink NOMA and enable more MUs to benefit from edge computing servers in resource-constrained UAV-assisted MEC environments. This synergy reduces MUs' uplink energy consumption but poses new challenges in resource allocation and UAV trajectory design. To address these challenges, we define a new metric called System Overhead Ratio (SOR) to reflect the system's QoS, and then consider a joint optimization problem of resource allocation, transmission power control, and UAV trajectory design, with the goal of minimizing the SOR. Given the NP-hard nature of the optimization problem, we propose a Lyapunov and convex optimization-based Low-complexity Online Resource allocation and Trajectory optimization method (LORT) to solve it, and further analyze the convergence and complexity of LORT. Finally, extensive simulations show that the proposed method surpasses other benchmarks, reducing the SOR by approximately$10\%$-$25\%$under various scenarios.

With the integration of IoT and 5G technologies, UAV crowd sensing has emerged as a promising solution to overcome the limitations of traditional Mobile Crowd Sensing (MCS) in terms of sensing coverage. As a result, UAV crowd sensing has been widely adopted across various domains. However, existing UAV crowd sensing methods often overlook the semantic information within sensing data, leading to low transmission efficiency. To address the challenges of semantic extraction and transmission optimization in UAV crowd sensing, this paper decomposes the problem into two sub-problems: semantic feature extraction and task-oriented sensing data transmission optimization. To tackle the semantic feature extraction problem, we propose a semantic communication module based on Multi-Scale Dilated Fusion Attention (MDFA), which aims to balance data compression, classification accuracy, and feature reconstruction under noisy channel conditions. For transmission optimization, we develop a reinforcement learning-based joint optimization strategy that effectively manages UAV mobility, bandwidth allocation, and semantic compression, thereby enhancing transmission efficiency and task performance. Extensive experiments conducted on real-world datasets and simulated environments demonstrate the effectiveness of the proposed method, showing significant improvements in communication efficiency and sensing performance under various conditions.

UAV-enabled multi-access edge computing (MEC) is expanding possibilities for integrated space-air-ground networks, especially in the 5G era and beyond. In this scenario, tasks from mobile users (MUs) are offloaded to nearby UAVs for execution, with results returned upon completion. However, the unpredictable mobility of MUs, coupled with dynamic network conditions and fluctuating resource availability, can degrade the reliability of communication links, leading to increased delivery latency, particularly for tasks involving large computational results. To meet stringent QoS requirements, adaptive task migration across UAVs is essential to minimize latency. To address this issue, in this paper, we first investigateComputationTaskMiGration (CTMiG) problem in UAV-enabled dynamic MEC networks, focusing on joint optimization of task-serving (offloading and migration) decisions to reduce latency for all MUs. We propose the ILCTS algorithm, an imitation learning-based joint optimization method that adaptively adjusts scheduling strategies in response to environmental changes. An improved PPO algorithm is first proposed to train a policy and generate expert data, followed by generative adversarial imitation learning to imitate the data and continuously explore new ones through online learning to enhance the policy. Experimental results demonstrate that our algorithm achieves superior performance in training accuracy and average latency compared to other representative methods.

Vehicle GPS devices provide abundant trajectory data that can be exploited to generate helpful pick-up service recommendations for taxi drivers. However, existing trajectory clustering approaches struggle to perform well on trajectory data with different distribution characteristics (e.g., dense in downtown and discrete in suburbs) simultaneously. Additionally, current prediction models mainly focus on subsection prediction but fail to produce accurate multisection predictions. To this end, we propose a recommendation framework, namely TaxiGuider, that can generate accurate pick-up cluster recommendations for taxi drivers. First, historical pick-up points are extracted from the entire vehicle trajectory data after preprocessing. Then, a graph Laplacian-based multiple spatial-temporal clustering approach is presented to generate clusters that can effectively match the distribution of trajectory data. Furthermore, a pick-up frequency prediction model that employs a multi-head attention mechanism is proposed to produce accurate multisection predictions that can help taxi drivers make comprehensive considerations for their next destination. Finally, top$N$clusters with the highest predicted pick-up frequency are recommended to the target taxis according to their request. Experimental results on real-world datasets suggest that TaxiGuider outperforms state-of-the-art approaches in terms of both subsection and multisection predictions. Moreover, it produces pick-up cluster recommendations with superior prediction and classification accuracy simultaneously.

Online disease diagnosis, gathering the patients’ symptoms and making diagnoses through online dialogue, grows rapidly worldwide. Manual-based approach, e.g., Haodaifu, employs real-world doctors, providing high-quality but high-cost medical services. In contrast, machine-based approach, e.g., 01bot, that utilizes machine learning models can make automatic diagnosis but lacks reliable accuracy. While some work has enabled human-AI collaboration in disease diagnosis, their collaboration pattern is simple and needs to be further improved. Therefore, we aim to introduce a doctor-enhanced and low-cost human-AI collaboration pattern. There are two key challenges. 1) How to utilize expert knowledge in doctor feedback to enhance AI’s capability? 2) How to design a collaboration workflow to achieve a low-cost doctor workload while ensuring accuracy? To address the above challenges, we propose the Human-AI collaboration framework for disease diagnosis via doctor-enhanced transformer, called HAIformer. Specifically, to enhance AI’s capability, we propose a machine module that leverages doctors’ medical knowledge through doctor-enhanced attention, using a graph attention-based matrix; to reduce doctor workload, we propose an activation module that uses two units in a cascading manner for human-AI allocation. Experiments on four real-world datasets show that HAIformer can achieve up to 91.2% accuracy with only 18.9% human effort and one-third of dialogue turns. Further real-world clinic study highlights its advantages in practical applications.

The rapid development of Low Earth Orbit (LEO) satellite networks has provided ubiquitous Internet access to users around the world, especially in areas where there are no terrestrial networks. However, a dish can only communicate with one of the available satellites when uploading data in the current framework, resulting in low communication efficiency. As the number of satellites continues to increase, the current framework cannot make full use of the user-satellite link resources. In this paper, we first conduct a measurement of Starlink’s network performance and report some unique features. Then, we propose an adaptive multi-link data allocation framework for LEO satellite networks where a dish can communicate with multiple satellites at the same time to improve data transmission efficiency. With this framework, data can be split into chunks and uploaded simultaneously over multiple links. Our goal is to determine the data allocation strategies to jointly optimize the transmission latency and data processing costs. To this end, we propose a deep reinforcement learning-based algorithm integrated with the traffic prediction module to determine the optimal data allocation strategies in a dynamic network environment. Through extensive simulations, we demonstrate the effectiveness of our approach compared with baselines.

As AI-enabled machines become increasingly prevalent, there is a strong impetus to harness the complementary strengths of humans and machines to enhance productivity and reduce costs in collaborative workspaces such as manufacturing and warehouses [1]. However, efficient team coordination remains challenging due to the heterogeneity of team agents and the dynamic nature of human agents. Existing exact methods often rely on assumptions and mathematical models, which struggle to scale and accurately predict time-varying human performance [2]. While offline Reinforcement Learning (RL) demonstrates potential, it is time-consuming and heavily reliant on training data, often limited in practical factory settings [3]. Therefore, a scalable and data-efficient team coordination method that considers the varying capabilities of heterogeneous agents in collaborative systems is urgently needed to facilitate effective human-machine partnerships.

With rapid advancements in artificial intelligence (AI) technologies, AI-powered machines are increasingly capable of collaborating with humans to enhance decision-making in various human–machine collaboration scenarios, e.g., medical diagnosis, criminal justice, and autonomous driving. As a result, human–machine computing (HMC) has emerged as a promising computing paradigm that integrates the expertise of humans with the reliable data processing capabilities of machines. Using HMC to facilitate the processing of domain-specific tasks has a lot of potential, but is limited in system-level scalability, i.e., there is no one common easy-to-use interface. In this article, we present human-machine operating system(hmOS), an open extensible platform for researchers to experiment with HMC for investigating system-centric human–machine collaboration problems.hmOSsupports flexible human–machine collaboration on the strength of the quality-aware task decomposition and allocation. To achieve that, the underlying system architecture and runtime environment are first developed to build a foundational abstraction for the kernel ofhmOS. Second,hmOSfacilitates flexible human–machine collaboration through a suitability-based task allocation mechanism, quality estimation guided by fuzzy rules, and iterative feedback on result tuning. We implement the newly proposedhmOSin a prototype featuring interactive interfaces. Finally, we conduct extensive and realistic experiments to validate the effectiveness of our platform across diverse tasks, showcasing the broad feasibility ofhmOS.

This paper considers optimal traffic signal control in smart cities, which has been taken as a complex networked system control problem. Given the interacting dynamics among traffic lights and road networks, attaining controller adaptivity and scalability stands out as a primary challenge. Capturing the spatial-temporal correlation among traffic lights under the framework of Multi-Agent Reinforcement Learning (MARL) is a promising solution. Nevertheless, existing MARL algorithms ignore effective information aggregation which is fundamental for improving the learning capacity of decentralized agents. In this paper, we design a new decentralized control architecture with improved environmental observability to capture the spatial-temporal correlation. Specifically, we first develop atopology-aware information aggregationstrategy to extract correlation-related information from unstructured data gathered in the road network. Particularly, we transfer the road network topology into a graph shift operator by forming a diffusion process on the topology, which subsequently facilitates the construction of graph signals. A diffusion convolution module is developed, forming a new MARL algorithm, which endows agents with the capabilities of graph learning. Extensive experiments based on both synthetic and real-world datasets verify that our proposal outperforms existing decentralized algorithms.

Long-tail service recommendation provides an unexpected but reasonable experience for potential developers when they construct mashups. However, the lack of available information makes it difficult to recommend highly relevant long-tail services for target mashups. Collaborative tagging systems employ extensive tag records to replenish the available information of long-tail services, whereas existing tag-aware approaches are unable to learn multi-aspect embeddings from graphs with different structures and relationships for long-tail services. To this end, we present a novel approach, namely collaborative tag-aware graph neural network, to recommend satisfactory long-tail services by extracting multi-aspect embeddings. Firstly, a tensor decomposition is executed to parameterize mashups, tags, and services as low-dimensional vector representations, respectively. Then, an interaction-aware heterogeneous neighbor aggregation is presented to aggregate both neighboring node features and interaction strength to enhance the embedding quality of long-tail services. Next, a diffusion-aware homogeneous neighbor aggregation is proposed to assign higher weights for long-tail neighboring nodes so as to reduce the influence of popular neighboring nodes during the aggregation process. Furthermore, a type-aware attention network is employed to update the final node embedding by aggregating multi-aspect embeddings. Experimental results on two real-world Web service datasets indicate that the proposed approach generates superior accuracy and diversity than state-of-the-art approaches in the aspect of long-tail service recommendation.

Code translation, i.e., translating one kind of code language to another, plays an important role in scenarios such as application modernization and multi-language versions of applications on different platforms. Even the most advanced machine-based code translation methods can not guarantee an error-free result. Therefore, the participance of software engineer is necessary. Considering both accuracy and efficiency, it is suggested to work in a human-machine collaborative way. However, in many realistic scenarios, human and machine collaborate ineffectively - model translates first and then human makes further editing, without any interaction. To solve this problem, we propose hmCodeTrans, a novel method that achieves code translation in aninteractive human-machine collaborative way. It can (1) save the human effort by introducing two novel human-machine collaboration patterns: prefix-based and segment-based ones, which feed the software engineer's sequential or scattered editing back to model and thus enabling the model to make a better retranslation; (2) reduce the response time based on two proposed modules: attention cache module that avoids duplicate prefix inference with cached attention information, and suffix splicing module that reduces invalid suffix inference by splicing a predefined suffix. The experiments are conducted on two real datasets. Results show that compared with the baselines, our approach can effectively save the human effort and reduce the response time. Last but not least, a user study involving five real software engineers is given, which validates that the proposed approach owns the lowest human effort and shows the users’ satisfaction towards the approach.

It is pivotal and challenging for crowdsensing systems to guarantee the reliable uploading of sensory data from source devices (workers) to a centralized platform, in order to process sensing tasks accurately and fast. On one hand, with limited communication resources, uploading a massive amount of sensory data is not cost-effective. On the other hand, the disruption of uploading is inevitable because of stochastic network environments and worker dropout, resulting in extra wasting of resources. To address that, we focus on a collaborative uploading scenario and propose to reduce the uploading latency of sensory data by adaptive data allocation while retaining data integrity at the destination. A key technical challenge is to identify proper collaborative paths such that corresponding data allocation and uploading are reliable enough. As such, we formulate a joint optimization problem with the minimization goal of uploading latency by considering both path selection and data allocation. To mine helpful information from unstructured topology-aware data, we propose a new diffusion graph convolution module by forming information aggregation based on the diffusion process that characterizes the stochastic correlation of devices. After transforming the original problem into a primal-dual problem, an algorithm is then developed by adapting Advantage Actor-Critic (A2C) framework embedded with the diffusion graph convolution module. With extensive experiments, it is validated that the newly developed algorithm improves collaborative uploading by reducing uploading latency and also stabilizing the queue state of intermediate devices, compared to existing heuristic and learning-based methods.

The ever-growing Internet of Things (IoT) provides a powerful means for complex and changeable environmental monitoring. Directional sensor networks (DSNs), as a typical architecture of IoT, can efficiently facilitate various digital and intelligent IoT applications. In the DSNs, due to the asymmetry in coverage focus and diversity in detection angle of the directional IoT sensors, how to enhance the coverage performance with the limited sensors becomes a new challenge. To this end, we develop a novel sensor redeployment scheme based on the minimum exposure path (MEP) to optimize the coverage performance of the DSNs. Specifically, we first propose a minimum exposure path searching algorithm based on the particle swarm optimization (MEP-PSO) algorithm with the target of obtaining the MEP in the DSNs. With this algorithm, the traditional MEP problem can be analyzed and simplified by conducting the grid discretization and building the weighted undirected graph. Then, an MEP-based coverage optimization (MEP-CO) algorithm is proposed to determine the optimal deployment locations and the dispatch sensors so that the IoT sensors can be dynamically redeployed to achieve the coverage optimization. After that, we derive the formula for the coverage upper bound (CUB) and develop a CUB algorithm to provide a benchmark for evaluating the effectiveness of different coverage optimization algorithms. Simulation results demonstrate that the proposed coverage optimization scheme can significantly promote the minimum exposure value (MEV) and coverage ratio of the monitoring area compared with the existing algorithms.

Currently, the complex traffic environment challenges the fast and accurate response of a connected autonomous vehicle (CAV). More importantly, it is difficult for different CAVs to collaborate and share knowledge. To remedy that, this paper proposes a selective federated reinforcement learning (SFRL) strategy to achieve online knowledge aggregation strategy to improve the accuracy and environmental adaptability of the autonomous driving model. First, we propose a federated reinforcement learning framework that allows participants to use the knowledge of other CAVs to make corresponding actions, thereby realizing online knowledge transfer and aggregation. Second, we use reinforcement learning to train local driving models of CAVs to cope with collision avoidance tasks. Third, considering the efficiency of federated learning (FL) and the additional communication overhead it brings, we propose a CAVs selection strategy before uploading local models. When selecting CAVs, we consider the reputation of CAVs, the quality of local models, and time overhead, so as to select as many high-quality users as possible while considering resources and time constraints. With above strategic processes, our framework can aggregate and reuse the knowledge learned by CAVs traveling in different environments to assist in driving decisions. Extensive simulation results validate that our proposal can improve model accuracy and learning efficiency while reducing communication overhead.

A fundamental issue of the vehicular digital twin (DT) is efficiently synchronizing the data between the DT and the vehicular user (VUE). In this paper, we consider the heterogeneous vehicular networks (HetVNets) in which a VUE can connect to the network through different networks. The HetVNets can improve the efficiency of communication by providing seamless connections. However, the uneven distribution of VUEs and the dynamics of HetVNets make the environment more complex. Therefore, we propose the network selection algorithm for data synchronization between VUEs and DTs in the HetVNets, where the behaviour between the VUEs is considered as a competition for wireless resources. A learning-based prediction model residing in the DT is developed where the DT can predict the waiting time of each relay and transmit the predicted results to the VUE for decision-making. We model the network selection problem as a potential game considering both the transmission time and the waiting time obtained from the prediction model and prove the existence of Nash equilibrium (NE). We analyze the performance of the proposed algorithm, and simulation results show that our approach can effectively find the optimal strategy while achieving a fast convergence speed and high-level performance compared to the baselines.

We witnessed great advancement in Artificial Intelligence (AI) powered technologies in recent years, and yet, when applied to certain high-stake contexts, such as medical diagnosis, automatic driving and criminal justice, they are not qualified. This matter can be greatly settled by Human-Machine Computing (HMC), which is an effective computing paradigm that couples the expertise and demonstration abilities of humans with the high-performance computing power of machines. This work studies an optimal task scheduling problem for HMC systems, where various tasks are decomposed and dispatched to humans and AI-enabled machines to provide significantly better benefits compared to either type of computing resources in isolation. However, designing such optimal task scheduling is challenging because of the stochastic hybrid features of machines, as well as various human professional abilities. Considering the Quality of Service (QoS) and the heterogeneity of human-machine computing resources, we propose CoupHM, a feasible task scheduler using gradient based optimization for HMC systems. In particular, we firstly present the underlying architecture of HMC system and details of the task-driven workload model. On that basis, we then formulate the objective optimization problem to be solved and describe the composition of the CoupHM scheduler. Finally, the performance of our solution is evaluated by the simulation experiments, and the results indicate that the proposed scheduler has preferable performance both in balancing resources and guaranteeing QoS, which can serve as guidelines for future research on HMC systems.

Driven by state-of-the-art AI technologies, human-AI collaboration has become an important area in computer supported teamwork research. Principles for Human-Machine Computing (HMC) have been discussed to accomplish complex goals by outsourcing some computational steps to humans and collaboratively achieving more accurate results. In HMC systems, however, the human participant brings great challenges to efficient provisioning of resources. Virtualization provides ideas for increasing the agility, flexibility and scalability of resources and has been applied in traditional computer systems, such as cloud computing. Unfortunately, existing hardware virtualization scheme is not ready to address utilization, and performance limitations associated with Human Processing Unit (HPU) resources. To tackle this problem, in this paper, we propose an efficient HPU resource virtualization framework for HMC systems. In particular, we firstly describe the modeling details of the HPU resource. And on this basis, we present the Time Division Multiplexing (TDM)-based virtualization scheme which aims to establish the mapping between each real HPU (rHPU) and its virtual HPUs (vHPUs). Secondly, we apply our minds to address the vHPU reconfiguration problem by managing the vHPU waiting queue, and propose DvR-PSO algorithm. Finally, the performance of our proposed HPU virtualization framework is evaluated through simulation experiments, and the results show that our solution can make remarkable effectiveness, which can serve as guidelines for future research on HMC systems.

By placing popular contents on the network edges, edge caching becomes a promising technique to improve the quality of experience (QoE) of the end users and reduce backhaul link congestion. In this paper, we examine an open market of crowdsourced video edge caching, where within each time slot, the newcome private edge devices strategically declare their own bids to the Video Content Provider (VCP) operator for contributions; and the operator optimally recruits caching devices among the newcome and existing served devices to maximize the expected QoE, under a budget constraint. From the perspective of newcome edge devices, we propose and study a novel pricing problem, namely Pri-CVEC, to determine the bid prices for profit maximization. The problem is challenging due to the importing of strategic interactions between the newcome devices and the VCP operator, and competition between the newcome and the existing served devices.We formulate it as a stackelberg knapsack problem. By leveraging the dynamic programming and linear programming-relaxation method, we propose Pri-DP and Pri-LPR algorithm, respectively. We extensively conduct simulation experiments to verify the advantages of our approaches.

Accurately discovering hazards and issuing appropriate warnings to drivers in advance or performing autonomous control is the core of the Collision Avoidance (CA) system used to solve traffic safety problems. More comprehensive environmental awareness, diversified communication technologies, and autonomous control can make the CA system more accurate and effective, thereby improving driving safety. In addition, the assistance of Artificial Intelligence (AI) technology can make the CA system adapt to the environment and facilitate fast and accurate decisions. Considering the current lack of a thorough survey of driving safety with sensing, vehicular communications, and AI-based collision avoidance, in this paper, we survey existing researches for state-of-the-art data-driven CA techniques. Firstly, we discuss the major steps of CA and key research issues. For each step, we review the existing enabling techniques and research methods for CA in detail, including sensing and vehicular communication for safe driving, as well as CA algorithm design. Particularly, we present a comparison between the most common AI algorithms for different functions in the CA system. Testbeds and projects for CA are summarized next. Finally, several open challenges and future research directions are also outlined.

The complex traffic and road environment pose considerable challenges to the accuracy, timeliness, and adaptive ability of connected and autonomous vehicles (CAVs) in making driving decisions. This paper uses vehicle collaboration and integrates the adaptive learning capabilities of machine learning and the interpretation capabilities of expert systems (ESs) in a unified architecture to form a hybrid autonomous driving guidance system, which not only solves the “bottleneck” of knowledge acquisition during the construction of expert systems but also solves the “black box” phenomenon of machine learning in the decision-making process. First, an autonomous driving strategy based on deep reinforcement learning (DRL) is proposed for CAVs to make decisions and extract corresponding rules. Next, we design an ES knowledge base expansion method including rule extraction, rule sharing, and rule test. Particularly, vehicular blockchain is adopted to ensure user privacy and data security during the rule-sharing process. Third, hybrid autonomous driving guidance combining ES and machine learning is proposed for CAVs to make accurate and efficient decisions in different driving environments. Once the strategy is well trained, it can effectively guide CAVs to cope with the complex traffic environment. Extensive simulations validate the performance of our proposal in terms of decision-making accuracy, effectiveness, and safety.

Recent advancements in edge computing and edge caching provide a feasible solution to support a plethora of new applications such as on-demand videos, AR/VR, road surveillance. However, to apply edge caching in vehicular scenarios is still difficult due to the unkonwn request pattern of vehicular users and intermittent service links between vehicles and edge servers (e.g., Road Side Units, RSUs). In this paper, we aim to investigate the vehicular edge caching problem in practical vehicular scenarios by considering higher hit ratio, while avoiding interruption of caching services. Specifically, to obtain a higher hit ratio, we firstly propose an on-demand adaptive cache algorithm. The algorithm can adjust the eviction time of cached contents by tracking the dynamics of requests and content popularity. We then develop an analysis framework to model the interruption performance of caching services from RSUs. Through diffraction approximation theory, the service process can be modeled as a joint process of the movement and stopping of vehicles to deduce the interruption ratio. To apply the on-demand adaptive cache algorithm in practical scenarios, the final caching decisions should be corrected by incorporating the interruption performance. Therefore, a$\alpha $-fair utility-oriented vehicular edge caching scheme is developed, which can achieve the tradeoff of hit ratio and interruption ratio. Performance evaluation shows the advantages of our proposed vehicular caching scheme in hit ratio, accuracy of analysis model, utility, respectively.

The rapid growth of connected and autonomous vehicles (CAVs) shows an urgent demand for driving and transportation-related data, which gives rise to vehicular crowdsensing systems (VCSs). Nevertheless, the existing centralized VCS framework mainly faces the system reliability problem while the decentralized one cannot satisfy the management flexibility. In addition, when the privacy preservation scheme that prevents information leakage encounters the user selection scheme that desires detailed information of participants, how to balance this seemingly irreconcilable contradiction is inevitable for VCS. To remedy that, we take the first research attempt and explore the balance point between the system management, privacy preservation, and quality of experience (QoE) of participants. By fully exploiting the characters of participating entities, a blockchain-enabled conditional decentralized VCS is proposed in this paper. Firstly, we propose a privacy-preserving scheme where the zk-SNARK proof combines with the mixed-task smart contract to guarantee the interaction process will not reveal any private information of participants. Secondly, we propose an efficient reputation management mechanism that renders certain the participants can get a satisfactory QoE even under the condition that the private information of users is secured. And also, the malicious operations in the system will be effectively supervised. Theoretical analysis and extensive simulations demonstrate the security and efficiency properties of privacy preservation and indicate the effectiveness of reputation management.

Point-of-interest (POI) recommendation has a wide range of application values in smart city services computing. However, extreme sparsity of user-POI matrix seriously affects the recommendation accuracy. Rich contextual information is often utilized to solve data sparsity, whereas how to efficiently integrate them becomes another challenge. To this end, we merge the contextual information into probabilistic diffusion process to propose a novel approach, namely context-enhanced probabilistic diffusion, to generate satisfying POI recommendations under sparse data environment. First, the check-in data is preprocessed to construct the relevant scores that can reflect the relevant degrees between users and POIs expressly. Then, we extract social explicit and implicit trusts from user relationships, and integrate them with time influence to present a time-enhanced social diffusion process to obtain time-social probabilistic score. Next, by merging time factor into geographical distance, a time-enhanced geographical diffusion process is executed to generate time-geographical probabilistic score. Furthermore, we present a context-aware probabilistic matrix factorization to predict the relevant score for a target user on each POI. Finally, unchecked-in POIs with highest predicted relevant scores are recommended for the target user. Experiments executed on real-world datasets suggest that, the proposed approach outperforms the state-of-the-art approaches in terms of the recommendation accuracy.

By driving vehicles in constant spacing, platooning is a promising way to enable a safer and faster mobility with higher lane capacity and energy efficiency. On one hand, recent advances in vehicular communication technologies improve the usefulness of platooning. On the other hand, the string instability in platooning is easily created by the unavoidable communication delays. In this paper, we focus on improving the performance of intraplatoon communications by considering the impact of non-line-of-sight (NLOS), which is typically isolated in most of present works. To do that, we first evaluate the impact of NLOS due to the vehicles as obstacles on signal attenuation among platoon members by developing an analytical mode based on the knife-edge model. To obtain the optimal communication performance, an power control problem is formulated by considering NLOS and multi-user interference. By resorting to the graph neural network (GNN), which can achieve an excellent performance in learning dynamic graph characteristics, an efficient power control policy is developed after modeling the inter-vehicle communication links in the platoon as a fully connected interference graph. Extensive simulations finally validate the performance of our method.

The travel delay caused by incidents severely reduces the efficiency of traffic. This symptom has been relieved with the development of advanced communication technologies. However, the emergency traffic information (ETI) is meaningless for vehicles which do not traverse the incident segment. Unlike most existing studies concentrating on the network performance during the dissemination of ETI to all vehicles, this paper proposes a joint traffic-communication optimization strategy (JTCS) to reduce the extra cost caused by unnecessary communication, which minimizes the total communication and traffic cost by transmitting the ETI to the worthy vehicles who need the ETI. Specifically, we capture the optimal targeted ETI transmission strategy with combination of radio resource allocation strategy (RRAS) and traffic-influencing transmission strategy (TTS), which can be converted into a bi-level optimization problem. The lower-level problem minimizes the total cost by Lagrangian method and obtains the optimal RRAS when the TTS is given. The upper-level problem develops the optimal TTS based on the optimal RRAS obtained in the lower-level problem. Simulation results using SUMO and MATLAB indicate that JTCS can achieve minimal total cost of ETI transmission and vehicle rerouting by comparing with existing approaches.

Recommender system (RS) suggests relevant objects to generate personalized service and minimize information overload issue. User-based collaborative filtering (UBCF) plays a dominant role in practical RSs. However, traditional UBCF suffers from a recommendation overfitting problem, i.e., recommendations generated by UBCF usually concentrate on popular items, resulting in lower diversity. In addition, UBCF cannot maintain a reasonable tradeoff between the accuracy and diversity of recommendations because raising the diversity is often accompanied by a decrease in accuracy. In this article, we propose a novel approach, namely link-based collaborative filtering, to enhance the recommendation accuracy and diversity simultaneously without employing additional complex information. First, a user–item bipartite network is constructed based on the user–item rating matrix of RSs. Then, a global–local weighted bipartite modularity is presented to conduct link partition so that links with the same community can not only be relatively denser but also own the same characteristic. Furthermore, redundant links are removed from each community by utilizing a link reduction algorithm so that neighborhood of a target user can be selected according to the more efficient nonredundant links. Finally, rating prediction is executed based on the rating information of neighborhood. Also, items owning the highest predicted rating scores will be recommended to the target user. Experimental results from three real datasets of RSs suggest that, without taking advantage of special additional data, our proposed approach outperforms the state-of-the-art studies and is able to generate personalized recommendations with satisfying accuracy and diversity simultaneously.

The positioning accuracy of the existing vehicular Global Positioning System (GPS) is far from sufficient to support autonomous driving and ITS applications. To remedy that, leading methods such as ranging and cooperation have improved the positioning accuracy to varying degrees, but they are still full of challenges in practical applications. Especially for cooperative positioning, in addition to the performance of methods, cooperators may provide false data due to attacks or selfishness, which can seriously affect the positioning accuracy. By fully exploiting the characteristics of blockchain and edge computing, this paper proposes a vehicular blockchain-based secure and efficient GPS positioning error evolution sharing framework, which improves vehicle positioning accuracy from ensuring security and credibility of cooperators and data. First, by analyzing the GPS error, a bridge can be established between the sensor-rich vehicles and the common vehicles to achieve cooperation by sharing the positioning error evolution at a specific time and location. Particularly, the positioning error evolution is obtained by a deep neural network (DNN)-based prediction algorithm running on the edge server. We further propose to use blockchain technology for storage and sharing the evolution of positioning errors, mainly to guarantee the security of cooperative vehicles and mobile edge computing nodes (MECNs). In addition, the corresponding smart contracts are designed to automate and efficiently perform storage and sharing tasks as well as solve inconsistencies in time scales. Extensive simulations based on actual data indicate the accuracy and security of our proposal in terms of positioning error correction and data sharing.

As a sub-class of internet of things (IoTs), wireless sensor networks (WSNs) are becoming ubiquitous in recent years, which makes the efficient coverage of sensors challenging. Traditionally, WSNs are composed of omni-directional sensors, which, however, are still limited to unadjustable sensing angle and superfluous energy consumption. Fortunately, these limitations can be overcome by deploying directional sensors in WSNs, thus forming directional sensor networks, namely DSNs. Therefore, it is necessary to propose efficient coverage optimization methods for DSNs to solve the minimum exposure path (MEP) problem that refers to a path along which the intruder can go through WSNs with lowest detection probability. In this paper, a novel MEP-PSO algorithm-based coverage optimization mechanism is proposed to improve the coverage quality in DSNs. With our coverage optimization mechanism, the traditional MEP problem is analyzed by means of discrete geometric theories while the path searching performance is improved based on the particle swarm optimization (PSO) algorithm. Specifically, the deployment scenario is firstly discretized into multiple square grids with uniform sizes. The weighted undirected graph is thus constructed in which the path segment exposure of MEP can be analyzed by discrete geometric theory. Based on the analysis, the feasibility of PSO is evaluated and enhanced in terms of MEP searching. Using our algorithm, the coverage performance of DSNs can be improved significantly by dynamically adjusting the positions of directional sensors. Finally, we conduct extensive experiments to validate the effectiveness of our work.

Transforming our roads into smart roads is an indispensable step towards future self-driving systems, and therefore has drawn increasing attention from both academia and industry. To this end, this paper develops a novel cost-effective IoT-based target detection system utilizing the multi-sensor data fusion technology with a particular focus on pedestrian detection, as an important component of smart road system. Particularly, the developed intelligent pedestrian detection module (${i}$PDM) consists of three major sensors, i.e., Doppler microwave radar sensor, passive infrared (PIR), and geomagnetic sensor. A multi-sensor data fusion algorithm is developed to fuse the sensor data and achieves reliable target detection. After that, ${i}$PDM sends the relevant warning signal wirelessly to nearby base station and vehicles. Experiments are conducted on real traffic environment to evaluate the performance of ${i}$PDM. The results validate the high reliability of ${i}$PDM with an average 91.7% detection accuracy. Moreover, to our best knowledge, ${i}$PDM is the first IoT-based implementation for pedestrian detection of smart roads. It is necessary to highlight that ${i}$PDM is a low-cost, low-power, wide-coverage pedestrian detection system where the cost of a single ${i}$PDM is only US $ 30, which makes it suitable to large-scale deployment.

Inappropriate lane following and changing behaviors of connected and autonomous vehicles (CAVs) can result in accidents, such as rear-end collision and side collision. To remedy that, the use of deep reinforcement learning (DRL) for autonomous driving decisions is currently a widely used promising solution. In this case, the accuracy and effectiveness of such a machine learning (ML) model is quite essential for this artificial intelligence (AI)-enabled CAVs. This article proposes a blockchain-based collective learning (BCL) framework for autonomous lane-changing systems. Four key issues, namely, learning efficiency, data security, users' privacy, as well as communication burden, are addressed by applying collective learning, vehicular blockchain, and knowledge transfer. First, we model the lane-changing problem as a DRL process and learn the autonomous lane-changing strategy through the deep deterministic policy gradient (DDPG) algorithm. Second, a single CAV involves a limited number of driving scenarios, and the independent learning method has the problem of inefficiency. Therefore, we propose a collective learning framework to utilize the “collective intelligence” shared by CAVs. Third, a vehicular blockchain is then applied to ensure the security and privacy of the user and data. In addition, the introduction of the blockchain can incentivize more users to participate in collective learning. Finally, in order to accelerate the learning process and achieve higher level performance while further reducing the communication burden, we use the corresponding knowledge extracted from the ML model such as human learning, as privileged information for sharing instead of directly sharing local ML models. Extensive simulation results validate the effectiveness and efficiency of our proposal in terms of learning efficiency, driving safety, as well as system security and robustness.

Realizing the ultra-low latency and high-accuracy solutions for rear-end collision is still challenging, especially under the condition in which many uncertainties exist. This paper proposes an artificial intelligence-based warning algorithm for rear-end collision avoidance. Three key issues are addressed by applying the neural network approach, including noises in positioning, inaccurate risk assessment, and enhanced comfort level of passengers. First, to filter the noises in positioning, wireless vehicular communications are leveraged; accurate relative lane positioning can be achieved to justify when two vehicles are in the same lane. Second, an online neural network model is developed to assess the risk of collisions in real time while driving. The algorithm can converge fast to a globally optimal solution and adapt to different traffic environments. Third, to maximize the comfort of passengers during the braking process, a graded warning strategy is developed at the prerequisite of guaranteed safety. With the above schemes sewed in to one framework, our proposal can achieve rear-end warning with reduced missing alarm rate, accurate risk assessment and enhanced comfort to passengers. The extensive simulations validate the effectiveness and accuracy of our proposal in terms of relative lane positioning, risk assessment, and collision avoidance.

The increasing per capita vehicle ownership has led to extremely serious traffic congestion, energy crisis and environment pollution. Electric vehicle, as a representative of energy structure transition and traffic component changes can effectively solve the mentioned issues. In this paper, we propose a novel energy consumption model for electric vehicles, Green wave band based Energy Consumption Model (GECM), which is built upon traffic signal control theory and combines with the distribution of energy consumption in a macroscopic view. This model designs green wave scenarios based on the traffic signal data in real traffic surroundings, and involves specific parameters like offset and green split for the analysis of energy consumption. Simulation results show that the energy saving and efficiency improvement are available and feasible for electric vehicles under the proposed model.

Wireless body area networks (WBANs) can be widely used in wireless medical, motion detection etc. However, the existence of interference results in the increase in energy consumption and delay. To mitigate interference, nodes are prevented from using the same or similar spectrum resources by adopting multi‐channel media access control (MAC) protocols. Here, the authors propose a multi‐channel MAC protocol towards energy efficiency and low interference (EIMAC). Firstly, the states of each channel are clarified by the channel mapping mechanism. A novel channel selection strategy, considering the unfairness between high or low priorities, then is carried out. After that, considering the characteristics of node including residual energy, user priority, and data volume, the authors propose a low energy consumption enabled transmission mechanism. Lastly, the authors utilise a novel collision avoidance mechanism to reduce the collision probability of packets. Numerical results show that EIMAC significantly enhance the performance of WBANs in terms of delay, throughput, and energy consumption.

Wireless Body Area Networks (WBANs) have attracted significant attentions because of their important role in medical applications with the development of requirements in health monitoring and diagnosis. IEEE 802.15.6, as the international standard for WBAN, supports network in operating on, in or around human body. Owing to the special propagation characteristics as affected by human body, WBAN needs reliable access mechanism to guarantee the stability of nodes access and information transmission. To achieve the high slot utilization rate and low average packet delay, we propose a gated scheduled access mechanism based on IEEE 802.15.6 and study the impact of allocation slot length on network performance. To examine the performance of our proposal, we conduct hardware experiment through a novel prototype system based on IEEE 802.15.6 standard. The experiment results show that the obtained optimal allocation slot length under the gated scheduled access mechanism can well satisfy the Quality of Service (QoS) requirements in different data rates, which is consistent with the results of theoretical analysis. The comparison results also show that our prototype system can be a practical reference in the future study of wireless body area network.