Fine-tuning large language models (LLMs) in federated settings enables privacy-preserving adaptation but suffers from cross-client interference due to model aggregation. Existing federated LoRA fine-tuning methods, primarily based on FedAvg, struggle with data heterogeneity, leading to harmful cross-client interference and suboptimal personalization. In this work, we propose FedALT, a novel personalized federated LoRA fine-tuning algorithm that fundamentally departs from FedAvg. Instead of using an aggregated model to initialize local training, each client continues training its individual LoRA while incorporating shared knowledge through a separate Rest-of-World (RoW) LoRA component. To effectively balance local adaptation and global information, FedALT introduces an adaptive mixer that dynamically learns input-specific weightings between the individual and RoW LoRA components, drawing conceptual foundations from the Mixture-of-Experts (MoE) paradigm. Through extensive experiments on NLP benchmarks, we demonstrate that FedALT significantly outperforms state-of-the-art personalized federated LoRA fine-tuning methods, achieving superior local adaptation without sacrificing computational efficiency.

Vertical Federated Learning (VFL) enables multiple clients with feature-partitioned data to collaboratively train models while preserving privacy by transmitting embeddings instead of raw data. However, such embeddings can still expose sensitive attributes (e.g., gender or race) unrelated to the target task, making them vulnerable to attribute inference attacks. Most existing privacy strategies may provide extra protection, but at the cost of reduced accuracy and excessive privacy budget. In this paper, we propose a novel equilibrium-driven VFL framework with selective privacy protection for sensitive attributes that are difficult to isolate from embeddings, thereby enhancing local privacy with minor accuracy compromise. We introduce two key innovations: (1) a NashCoder, which incorporates a surrogate head to jointly optimize accuracy and privacy; (2) an adaptive decomposition strategy based on Shapley values, which dynamically decomposes the global objective for distributed optimization from an equilibrium perspective. We theoretically analyze our framework and empirically evaluate it on three public datasets against five baselines, demonstrating significant improvements in the accuracy-privacy trade-off under various privacy settings. Extensive experimental results support our theoretical analysis.

Recent advances in Deep Neural Networks (DNNs) have enabled a wide range of intelligent mobile applications, but their computational demands pose challenges for resource-constrained devices. Collaborative edge inference addresses this by partitioning a DNN inference task into several subtasks across multiple network nodes. However, most existing methods assume known network parameters or fixed processing paths. In this paper, we consider a more complex setting where network parameters are unknown and multiple paths are available. The goal is to learn both the optimal path and the DNN layer assignment along it, while accounting for security threats and path-switching costs. We first derive structural insights under full information to reduce the decision space. We then formulate the learning problem as an adversarial group linear bandit with switching costs, where rewards follow a hybrid stochastic-adversarial process. To solve this, we propose B-EXPUCB, a new algorithm that combines ideas from blocked EXP3 and LinUCB, and show that it achieves sublinear regret. Extensive simulations demonstrate that B-EXPUCB outperforms existing methods in collaborative edge inference.

Foundation models (FMs) achieve strong performance across diverse tasks with task-specific fine-tuning, yet full parameter fine-tuning is often computationally prohibitive for large models. Parameter-efficient fine-tuning (PEFT) methods like Low-Rank Adaptation (LoRA) reduce this cost by introducing low-rank matrices for tuning fewer parameters. While LoRA allows for efficient fine-tuning, it requires significant data for adaptation, making Federated Learning (FL) an appealing solution due to its privacy-preserving collaborative framework. However, combining LoRA with FL introduces two key challenges: the \textbf{Server-Side Aggregation Bias}, where server-side averaging of LoRA matrices diverges from the ideal global update, and the \textbf{Client-Side Initialization Lag}, emphasizing the need for consistent initialization across rounds. Existing approaches address these challenges individually, limiting their effectiveness. We propose LoRA-FAIR, a novel method that tackles both issues by introducing a correction term on the server, enhancing aggregation efficiency and accuracy. LoRA-FAIR maintains computational and communication efficiency, yielding superior performance over state-of-the-art methods. Experimental results on ViT and MLP-Mixer models across large-scale datasets demonstrate that LoRA-FAIR consistently achieves performance improvements in FL settings.

Large Language Models (LLMs) have demonstrated impressive capabilities across various tasks, but fine-tuning them for domain-specific applications often requires substantial domain-specific data that may be distributed across multiple organizations. Federated Learning (FL) offers a privacy-preserving solution, but faces challenges with computational constraints when applied to LLMs. Low-Rank Adaptation (LoRA) has emerged as a parameter-efficient fine-tuning approach, though a single LoRA module often struggles with heterogeneous data across diverse domains. This paper addresses two critical challenges in federated LoRA fine-tuning: 1. determining the optimal number and allocation of LoRA experts across heterogeneous clients, and 2. enabling clients to selectively utilize these experts based on their specific data characteristics. We propose FedLEASE (Federated adaptive LoRA Expert Allocation and SElection), a novel framework that adaptively clusters clients based on representation similarity to allocate and train domain-specific LoRA experts. It also introduces an adaptive top-$M$ Mixture-of-Experts mechanism that allows each client to select the optimal number of utilized experts. Our extensive experiments on diverse benchmark datasets demonstrate that FedLEASE significantly outperforms existing federated fine-tuning approaches in heterogeneous client settings while maintaining communication efficiency.

Federated learning (FL) enables distributed devices to collaboratively train machine learning (ML) models while maintaining data privacy. However, the heterogeneous hardware capabilities of participating devices often result in significant training delays, as straggler clients with limited resources prolong the aggregation process. Existing solutions such as client selection, asynchronous FL, and partial training partially address these challenges but encounter issues such as reduced accuracy, stale updates, and compromised model performance due to inconsistent training contributions. To overcome these limitations, we propose FedEL, a federated elastic learning framework that enhances training efficiency while maintaining model accuracy. FedEL introduces a novel window-based training process, sliding the window to locate the training part of the model and dynamically selecting important tensors for training within a coordinated runtime budget. This approach ensures progressive and balanced training across all clients, including stragglers. Additionally, FedEL employs a tensor importance adjustment module, harmonizing local and global tensor importance to mitigate biases caused by data heterogeneity. The experiment results shows that FedEL achieves up to 3.87× improvement in time-to-accuracy compared to baselines while maintaining or exceeding final test accuracy.

Federated Learning (FL) is a distributed machine learning framework that efficiently reduces communication and preserves privacy. Existing FL algorithms typically rely on the assumption of direct communication between the server and clients for model data exchange. However, this assumption does not apply in many real-world scenarios where appropriate communication infrastructure is lacking, such as in remote smart sensing. To overcome this challenge, we propose a new framework, FedEx (Federated Learning via Model Express Delivery). FedEx employs mobile transporters, such as Unmanned Aerial Vehicles (UAVs), to establish indirect communication channels between the server and clients. We have developed two algorithms under this framework: FedEx-Sync and FedEx-Async, which differ based on whether the transporters operate on a synchronized or asynchronized schedule. Although indirect communication introduces variable delays in global model dissemination and local model collection, we demonstrate the convergence of both FedEx versions. Additionally, we explore the energy consumption of transporters, integrating it with the convergence bounds and proposing a bi-level optimization algorithm for efficient client assignment and route planning. Our experiments, conducted on two public datasets in a simulated environment, further demonstrate the efficacy of FedEx.

Quantum Data Networks (QDNs) have emerged as a promising framework in the field of information processing and transmission, harnessing the principles of quantum mechanics. QDNs utilize a quantum teleportation technique through long-distance entanglement connections, encoding data information in quantum bits (qubits). Despite being a cornerstone in various quantum applications, quantum entanglement encounters challenges in establishing connections over extended distances due to probabilistic processes influenced by factors like optical fiber losses. The creation of long-distance entanglement connections between quantum computers involves multiple entanglement links and entanglement swapping techniques through successive quantum nodes, including quantum computers and quantum repeaters, necessitating optimal path selection and qubit allocation. Current research predominantly assumes known success rates of entanglement links between neighboring quantum nodes and overlooks potential network attackers. This paper addresses the online challenge of optimal path selection and qubit allocation, aiming to learn the best strategy for achieving the highest success rate of entanglement connections between two chosen quantum computers without prior knowledge of the success rate and in the presence of a QDN attacker. The proposed approach is based on multi-armed bandits, specifically adversarial group neural bandits, which treat each path as a group and view qubit allocation as arm selection. Our contributions encompass formulating an online adversarial optimization problem, introducing the EXPNeuralUCB bandits algorithm with theoretical performance guarantees, and conducting comprehensive simulations to showcase its superiority over established advanced algorithms.

The fusion of complementary multimodal information is crucial in computational pathology for accurate diagnostics. However, existing multimodal learning approaches necessitate access to users’ raw data, posing substantial privacy risks. While Federated Learning (FL) serves as a privacy-preserving alternative, it falls short in addressing the challenges posed by heterogeneous (yet possibly overlapped) modalities data across various hospitals. To bridge this gap, we propose a Federated Multi-Modal (FedMM) learning framework that federatedly trains multiple single-modal feature extractors to enhance subsequent classification performance instead of existing FL that aims to train a unified multimodal fusion model. Any participating hospital, even with small-scale datasets or limited devices, can leverage these federated trained extractors to perform local downstream tasks (e.g., classification) while ensuring data privacy. Through comprehensive evaluations of two publicly available datasets, we demonstrate that FedMM notably outperforms two baselines in accuracy and AUC metrics.

Federated learning (FL) is a new distributed machine learning frame-work known for its benefits on data privacy and communication efficiency. Since full client participation in many cases is infeasible due to constrained resources, partial participation FL algorithms have been investigated that proactively select/sample a subset of clients, aiming to achieve learning performance close to the full participation case. This paper studies a passive partial client participation scenario that is much less well understood, where partial participation is a result of external events, namely client dropout, rather than a decision of the FL algorithm. We cast FL with client dropout as a special case of a larger class of FL problems where clients can submit substitute (possibly inaccurate) local model updates. Based on our convergence analysis, we develop a new algorithm FL-FDMS that discovers friends of clients (i.e., clients whose data distributions are similar) on-the-fly and uses friends’ local updates as substitutes for the dropout clients, thereby reducing the substitution error. Experiments on MNIST and CIFAR-10 confirmed the superior performance of FL-FDMS in handling client dropout in FL.

Federated learning (FL) with noisy labels poses a significant challenge. Existing methods designed for handling noisy labels in centralized learning tend to lose their effectiveness in the FL setting, mainly due to the small dataset size and the heterogeneity of client data. While some attempts have been made to tackle FL with noisy labels, they primarily focused on scenarios involving class-conditional noise. In this paper, we study the more challenging and practical issue of instance-dependent noise (IDN) in FL. We introduce a novel algorithm called FedBeat (Federated Learning with Bayesian Ensemble-Assisted Transition Matrix Estimation). FedBeat aims to build a global statistically consistent classifier using the IDN transition matrix (IDNTM), which encompasses three synergistic steps: (1) A federated data extraction step that constructs a weak global model and extracts high-confidence data using a Bayesian model ensemble method. (2) A federated transition matrix estimation step in which clients collaboratively train an IDNTM estimation network based on the extracted data. (3) A federated classifier correction step that enhances the global model’s performance by training it using a loss function tailored for noisy labels, leveraging the IDNTM. Experiments conducted on CIFAR-10 and SVHN verify that the proposed method significantly outperforms state-of-the-art methods.

Distributed quantum computing (DQC) holds immense promise in harnessing the potential of quantum computing by interconnecting multiple small quantum computers (QCs) through a quantum data network (QDN). Establishing long-distance quantum entanglement between two QCs for quantum teleportation within the QDN is a critical aspect, and it involves entanglement routing - finding a route between QCs and efficiently allocating qubits along that route. Existing approaches have mainly focused on optimizing entanglement performance for current entanglement connection (EC) requests. However, they often overlook the user's perspective, wherein the user making EC requests operates under a budget constraint over an extended period. Furthermore, both QDN resources (quantum channels and qubits) and the EC requests, reflecting the DQC workload, vary over time. In this paper, we present a novel user-centric entanglement routing problem that spans an extended period to maximize the entanglement success rate while adhering to the user's budget constraint. To address this challenge, we leverage the Lyapunov drift-plus-penalty framework to decompose the long-term optimization problem into per-slot problems, allowing us to find solutions using only the current system information. Subsequently, we develop efficient algorithms based on continuous-relaxation and Gibbs-sampling techniques to solve the per-slot entanglement routing problem. Theoretical performance guarantees are provided for both the per-slot and long-term problems. Extensive simulations demonstrate that our algorithm significantly outperforms baseline approaches in terms of entanglement success rate and budget adherence.

The multi-armed bandits (MAB) framework is widely used for sequential decision-making under uncertainty, finding applications in various domains, including computer and communication networks. To address the increasing complexity of real-world systems and their operational requirements, researchers have proposed and studied various extensions to the basic MAB framework. In this paper, we focus on an adversarial MAB problem inspired by real-world systems with combinatorial semi-bandit arms, switching costs, and anytime cumulative arm selection constraints. To tackle this challenging problem, we introduce the Block-structured Follow-the-Regularized-Leader (B-FTRL) algorithm. Our approach employs a hybrid Tsallis-Shannon entropy regularizer in arm selection and incorporates a block structure that divides time into blocks to minimize arm switching costs. The theoretical analysis shows that B-FTRL achieves a reward regret bound of $O\left( {{T^{\frac{{2a - b + 1}}{{1 + a}}}} + {T^{\frac{b}{{1 + a}}}}} \right)$ and a switching regret bound of $O\left( {{T^{\frac{1}{{1 + a}}}}} \right)$, where a and b are tunable algorithm parameters. By carefully selecting the values of a and b, we are able to limit the total regret to O(T2/3) while satisfying the arm selection constraints in expectation. This outperforms the state-of-the-art regret bound of O(T3/4) and expected constraint violation bound o(1), which are derived in less challenging stochastic reward environments. Additionally, we provide a high-probability constraint violation bound of $O(\sqrt T )$. To validate the effectiveness of the proposed BFTRL algorithm, numerical results are presented to demonstrate its superiority in comparison to other existing methods.

Machine learning has been adopted for efficient cooperative spectrum sensing. However, it incurs an additional security risk due to attacks leveraging adversarial machine learning to create malicious spectrum sensing values to deceive the fusion center, called adversarial spectrum attacks. In this paper, we propose an efficient framework for detecting adversarial spectrum attacks. Our design leverages the concept of the distance to the decision boundary (DDB) observed at the fusion center and compares the training and testing DDB distributions to identify adversarial spectrum attacks. We create a computationally efficient way to compute the DDB for machine learning based spectrum sensing systems. Experimental results based on realistic spectrum data show that our method, under typical settings, achieves a high detection rate of up to 99% and maintains a low false alarm rate of less than 1%. In addition, our method to compute the DDB based on spectrum data achieves 54%–64% improvements in computational efficiency over existing distance calculation methods. The proposed DDB-based detection framework offers a practical and efficient solution for identifying malicious sensing values created by adversarial spectrum attacks.

Multimodal Federated Learning (FL) integrates two crucial research areas in IoT scenarios: utilizing complementary multimodal data to enhance downstream inference performance and conducting decentralized training to safeguard privacy. However, existing studies primarily focus on applying FL methods after multimodal feature fusion, without fundamentally addressing multimodal FL across both feature and sample spaces. A notable tradeoff persists between the computational demands of multimodal information and the limited computing resources in IoT systems. To tackle this challenge, we propose a Joint Horizontal and Vertical (JHV) FL algorithm tailored for multimodal IoT systems. JHV employs vertical FL to distribute computing tasks across multimodal IoT devices (feature space) and horizontal FL to allocate tasks across multiple silos (sample space). Experimental results on two public multimodal datasets show that JHV outperforms three baseline methods, demonstrating its effectiveness for multimodal IoT systems, especially in rapid and accurate downstream tasks like classification and prediction.

Federated learning (FL) allows collaborative machine learning training without sharing private data. While most FL methods assume identical data domains across clients, real-world scenarios often involve heterogeneous data domains. Federated Prototype Learning (FedPL) addresses this issue, using mean feature vectors as prototypes to enhance model generalization. However, existing FedPL methods create the same number of prototypes for each client, leading to cross-domain performance gaps and disparities for clients with varied data distributions. To mitigate cross-domain feature representation variance, we introduce FedPLVM, which establishes variance-aware dual-level prototypes clustering and employs a novel $\alpha$-sparsity prototype loss. The dual-level prototypes clustering strategy creates local clustered prototypes based on private data features, then performs global prototypes clustering to reduce communication complexity and preserve local data privacy. The $\alpha$-sparsity prototype loss aligns samples from underrepresented domains, enhancing intra-class similarity and reducing inter-class similarity. Evaluations on Digit-5, Office-10, and DomainNet datasets demonstrate our method's superiority over existing approaches.

Multimodal federated learning (FL) targets the intersection of two promising research directions in Internet of Things (IoT) scenarios: 1) leveraging complementary multimodal information to enhance downstream inference performance and 2) conducting distributed training with privacy protection. However, the majority of existing works primarily focus on applying different FL methods in a straightforward manner after the multimodal feature fusion stage without fundamentally disentangling the multimodal FL across both the feature space and the sample space. There still exists an important tradeoff between the computationally demanding nature of multimodal information and the limited computing resources in IoT systems. To tackle this challenge, we propose a hybrid FL algorithm tailored for multimodal IoT systems (HFM). HFM utilizes vertical FL (VFL) to distribute computing resources across the feature space and horizontal FL (HFL) to distribute computing resources across the sample space. This innovative algorithm necessitates consideration of both stale information from the VFL component and perturbed gradients from the HFL component, which is not fully understood from a theoretical point. In this article, we theoretically prove that the convergence of HFM depends on the frequency of VFL communication and HFL communication, as well as the number of vertical partitions and horizontal partitions. Furthermore, we empirically demonstrate that HFM outperforms three types of baselines based on two public multimodal data sets, thereby making it practical for multimodal IoT systems that require rapid and accurate downstream inference tasks, such as classification, prediction, etc.

In this study, we address the emerging field of streaming federated learning (SFL) and propose local cache update rules to manage dynamic data distributions and limited cache capacity. Traditional federated learning (FL) relies on fixed data sets, whereas in SFL, data is streamed, and its distribution changes over time, leading to discrepancies between the local training data set and long-term distribution. To mitigate this problem, we propose three local cache update rules—first-in–first-out (FIFO), static ratio selective replacement (SRSR), and dynamic ratio selective replacement (DRSR)—that update the local cache of each client while considering the limited cache capacity. Furthermore, we derive a convergence bound for our proposed SFL algorithm as a function of the distribution discrepancy between the long-term data distribution and the client’s local training data set. We then evaluate our proposed algorithm on two data sets: 1) a network traffic classification data set and 2) an image classification data set. Our experimental results demonstrate that our proposed local cache update rules significantly reduce the distribution discrepancy and outperform the baseline methods. Our study advances the field of SFL and provides practical cache management solutions in FL.

Microservice (MS) structures a service application as a collection of independently deployable service modules, making it particularly suitable for delivering complex applications in distributed computing systems. This paper investigates MS architecture over Mobile Edge Computing (MEC) networks (hereafter referred to as EdgeMS) and studies an EdgeMS placement problem that aims to deploy MS modules over the MEC network in a manner that maximizes the reward of MS application providers. A novel algorithm called Dual-GNN Deep Deterministic Policy Gradient (DG-DDPG) is proposed to establish an intelligent EdgeMS placement policy for optimizing the location of MS modules and performing fractional computing resource allocation. DG-DDPG leverages the graph neural network (GNN) to comprehend the graph-structured information encapsulated in the MS application structure and MEC network. A dual-GNN core is constructed in DG-DDPG, one GNN for MS applications to distill knowledge from intricate connections between MS modules, and the other GNN for MEC networks to capture complicated interactions between edge sites when providing EdgeMS. DG-DDPG embeds the dual-GNN core in a DDPG-based reinforcement learning framework, which not only handles temporal dependencies between EdgeMS placement decisions for maximizing long-term reward but also supports continuous action space for enabling fractional resource allocation. In particular, the learning process of DG-DDPG is tailored to address hard constraints (i.e., computing capacity and MS application completeness) in the EdgeMS placement problem. We design constraint-based regularization terms and add them to the objective of DG-DDPG, which facilitates the identification of feasible placement decisions during learning. We carry out systematic experiments to evaluate the performance of DG-DDPG, and the results show that DG-DDPG outperforms state-of-the-art benchmarks in terms of reward, service delay and deployment cost.

Federated learning (FL) trains a global learning model by using a central server to collaborate with multiple decentralized clients. In a wireless network, the data transmission latency between a client and the FL server is substantially affected by signal quality dynamics and bandwidth allocation. FL clients require synchronized communication at each round to update their models simultaneously, which makes bandwidth allocation methods for conventional wireless tasks infeasible to use. Existing bandwidth allocation studies for FL mainly focused on allocating bandwidth of one bandwidth provider without cost. In this paper, we consider a more practical and challenging problem: how to assign the bandwidth to clients under multiple wireless providers to minimize the FL round length (i.e., the latency that FL finishes one round of model training and updating) with bandwidth capability and cost constraints? We propose a model that maps the problem into a new variant of the knapsack problem, called multi-dimensional max-min multiple knapsacks (MDM$^{\,3}$KP). Based on MDM$^{\,3}$KP, we create an iterative solution to find the client assignment and bandwidth allocation that minimizes the FL round length. Comprehensive simulation results show that the solution reduces the FL round length by up to 70.8% compared with other benchmarks.

Smart cameras with on-device deep learning inference capabilities are enabling distributed video analytics at the data source without sending raw video data over the often unreliable and congested wireless network. However, how to unleash the full potential of the computing power of the camera network requires careful coordination among the distributed cameras, catering to the uneven workload distribution and the heterogeneous computing capabilities. This paper presents CrossVision, a distributed framework for real-time video analytics, that retains all video data on cameras while achieving low inference delay and high inference accuracy. The key idea behind CrossVision is that there is a significant information redundancy in the video content captured by cameras with overlapped Field-of-Views (FoVs), which can be exploited to reduce inference workload as well as improve inference accuracy between correlated cameras. CrossVision consists of three main components to realize its function: a Region-of-Interest (RoI) Matcher that discovers video content correlation based on a segmented FoV transformation scheme; a Workload Balancer that implements a randomized workload balancing strategy based on a bulk-queuing analysis, taking into account the cameras’ predicted future workload arrivals; an Accuracy Guard that ensures that the inference accuracy is not sacrificed as redundant information is discarded. We evaluate CrossVision in a hardware-augmented simulator and on real-world cross-camera datasets, and the results show that CrossVision is able to significantly reduce inference delay while improving the inference accuracy compared to a variety of baseline approaches.

With increasingly strict data privacy regulations, federated learning (FL) has become one of the most often heard machine learning techniques due to its privacy-preserving trait. To efficiently implement the FL intelligence, researchers recently resort to a newly emerged computing paradigm, mobile-edge computing (MEC), and bring about a burst of works. However, most existing works neglect practical issues in MEC systems, e.g., device heterogeneity, unstable channel conditions, and unknown user mobility. Any of them, if not handled properly, can cause fatal failures to FL. This article proposed a novel FL framework, called multicore FL (MC-FL), to help FL intelligence land successfully on realistic MEC systems. A distinct feature of MC-FL is maintaining and training multiple global models (GMs) that exhibit different tradeoffs between learning performances and computational complexity. While this modification seems simple, it can effectively handle the device heterogeneity and device status variations, and improve the compatibility and robustness of FL. Furthermore, MC-FL employs a partial client participation scheme that allows participating clients to vary across time. This enables MC-FL to function under uncertain mobile environments. We rigorously prove the convergence of the designed MC-FL framework. In particular, we propose an online client scheduling scheme for MC-FL to judiciously schedule clients for training multiple GMs in a manner that minimizes the completion time of MC-FL. We also provide a service provisioning scenario with MC-FL to show how service subscribers could benefit from multiple GMs and improve their Quality of Experience (QoE). We evaluate our method on real-world data sets, and the results show that MC-FL outperforms state-of-the-art benchmarks.

The rapid uptake of intelligent applications is pushing deep learning (DL) capabilities to mobile devices. However, the heterogeneities in device capacity, DNN performances, and user preferences make it challenging to provide satisfactory Quality of Experience (QoE) to mobile users. This paper studies automated customization for DL inference on mobile devices (termed as on-device inference), and our goal is to enhance user QoE by configuring the on-device inference with an appropriate DNN for users under different usage scenarios. The core of our method is a DNN selection module that learns user QoE patterns on-the-fly and identifies the best-fit DNN for on-device inference with the learned knowledge. It leverages an online learning algorithm,NeuralUCB, that has excellent generalization ability for handling various user QoE patterns. We also embed the knowledge transfer technique in NeuralUCB to expedite the learning process. However, NeuralUCB frequently solicits QoE ratings from users, which incurs non-negligible inconvenience. To address this problem, we design feedback solicitation schemes to reduce the number of QoE solicitations while maintaining the learning efficiency of NeuralUCB. A pragmatic problem,aggregated QoE, is further investigated to improve the practicality of our framework. We conduct experiments on both synthetic and real-world data. The results indicate that our method efficiently learns the user QoE pattern with few solicitations and provides drastic QoE enhancement for mobile devices.

Multi-server Federated learning (FL) has been considered as a promising solution to address the limited communication resource problem of single-server FL. We consider a typical multi-server FL architecture, where the coverage areas of regional servers may overlap. The key point of this architecture is that the clients located in the overlapping areas update their local models based on the average model of all accessible regional models, which enables indirect model sharing among different regional servers. Due to the complicated network topology, the convergence analysis is much more challenging than in single-server FL. In this paper, we firstly propose a novel MS-FedAvg algorithm for this multi-server FL architecture and analyze its convergence on non-iid datasets for general non-convex settings. Since the number of clients located in each regional server is much less than single-server FL, the bandwidth of each client should be large enough to successfully communicate training models with the server, which indicates that full client participation can work in multi-server FL. Also, we provide the convergence analysis of the partial client participation scheme and develop a new biased partial participation strategy to further accelerate convergence. Our results indicate that the convergence results highly depend on the ratio of the number of clients in each area type to the total number of clients in all three strategies. The extensive experiments show remarkable performance and support our theoretical results.

Catering to the proliferation of Internet of Things devices and distributed machine learning at the edge, we propose an energy harvesting federated learning (EHFL) framework in this paper. The introduction of EH implies that a client’s availability to participate in any FL round cannot be guaranteed, which complicates the theoretical analysis. We derive novel convergence bounds that capture the impact of time-varying device availabilities due to the random EH characteristics of the participating clients, for both parallel and local stochastic gradient descent (SGD) with non-convex loss functions. The results suggest that having a uniform client scheduling that maximizes the minimum number of clients throughout the FL process is desirable, which is further corroborated by the numerical experiments using a real-world FL task and a state-of-the-art EH scheduler.

Advances in deep learning (DL) have triggered an explosion of mobile intelligence, posing a soaring demand for computing resources that cannot be satisfied by mobile devices. In this article, we employedge computingto deliver better DL inference services to end users. The key is to leverage deep neural network (DNN) ensemble techniques that provide state-of-the-art performance for many machine learning applications in terms of inference accuracy and robustness. Compared to end devices, the edge computing platform is endowed with more powerful computing resources, making it feasible to implement DNN ensembles for DL inferences. However, due to the constrained computing capacity of edge servers and the possible service response deadline, an edge server can only use a limited number of DNNs to construct DNN ensembles. This poses a unique problem, namely, DNN ensemble selection, for identifying the best-fit DNN ensembles. We propose a novel algorithm called automated DNN ensemble selection (AES) algorithm to solve this problem. Because DNNs exhibit performance variations over different distributions of input data, AES adaptively determines a DNN ensemble according to the features of admitted inference tasks. AES is an online learning algorithm that learns DNNs’ in-use performance over time. An ensemble selection rule is further designed as a subroutine of AES to recruit members into the DNN ensemble based on the accuracy and diversity of DNNs. In particular, we theoretically prove that AES can achieve asymptotic optimality. We carry out experiments on real-world data sets. The results show that using the DNN ensemble technique on edge computing platforms dramatically improves the DL inference quality, and AES outperforms other benchmark schemes.

Edge devices, including, in particular, mobile devices, have been emerging as an increasingly more important platform for deep neural network (DNN) inference. Typically, multiple lightweight DNN models generated using different architectures and/or compression schemes can fit into a device, thus selecting an optimal one is crucial in order to maximize the users’ Quality of Experience (QoE) for edge inference. The existing approaches to device-aware DNN optimization are usually time consuming and not scalable in view of extremely diverse edge devices. More importantly, they focus on optimizing standard performance metrics (e.g., accuracy and latency), which may not translate into improvement of the users’ actual subjective QoE. In this article, we propose a novel automated and user-centric DNN selection engine, called$\mathsf {Aquaman}$, which keeps users into a closed loop and leverages their QoE feedback to guide DNN selection decisions. The core of$\mathsf {Aquaman}$is a neural network-based QoE predictor, which is continuously updated online. Additionally, we use neural bandit learning to balance exploitation and exploration, with a provably efficient QoE performance. Finally, we evaluate$\mathsf {Aquaman}$on a 15-user experimental study as well as synthetic simulations, demonstrating the effectiveness of$\mathsf {Aquaman}$.

With the growth of intelligent Internet of Things (IoT) applications and services, deep neural network (DNN) has become the core method to power and enable increased functionality in many smart IoT devices. However, DNN training is difficult to carry out on end devices because it requires a great deal of computational power. The conventional approach to DNN training is generally implemented on a powerful computation server; nevertheless, this approach violates privacy because it exposes the training data to curious service providers. In this article, we consider a collaborative DNN training system between a resource-constrained end device and a powerful edge server, aiming at partitioning a DNN into a front-end part running on the end device and a back-end part running on the edge server to accelerate the training process while preserving the privacy of the training data. With the key challenge being how to locate the optimal partition point to minimize the end-to-end training delay, we propose an online learning module, called learn-to-split (L2S), to adaptively learn the optimal partition point on the fly. This approach is unlike existing efforts on DNN partitioning that relies heavily on a dedicated offline profiling stage. In particular, we design a new contextual bandit learning algorithm called LinUCB-E as the basis of L2S, which has provable theoretical learning performance and is ultralightweight for easy real-world implementation. We implement a prototype system consisting of an end device and an edge server, and experimental results demonstrate that L2S can significantly outperform state-of-the-art benchmarks in terms of reducing the end-to-end training delay and preserving privacy.

Defense strategies have been well studied to combat Byzantine attacks that aim to disrupt cooperative spectrum sensing by sending falsified versions of spectrum sensing data to a fusion center. However, existing studies usually assume network or attackers as passive entities, e.g., assuming the prior knowledge of attacks is known or fixed. In practice, attackers can actively adopt arbitrary behaviors and avoid pre-assumed patterns or assumptions used by defense strategies. In this paper, we revisit this security vulnerability as an adversarial machine learning problem and propose a novel learning-empowered attack framework named Learning-Evaluation-Beating (LEB) to mislead the fusion center. Based on the black-box nature of the fusion center in cooperative spectrum sensing, our new perspective is to make the adversarial use of machine learning to construct a surrogate model of the fusion center's decision model. We propose a generic algorithm to create malicious sensing data using this surrogate model. Our real-world experiments show that the LEB attack is effective to beat a wide range of existing defense strategies with an up to 82 percent of success ratio. Given the gap between the proposed LEB attack and existing defenses, we introduce a non-invasive method named as influence-limiting defense, which can coexist with existing defenses to defend against LEB attack or other similar attacks. We show that this defense is highly effective and reduces the overall disruption ratio of LEB attack by up to 80 percent.

Federated Learning (FL) has been considered as an appealing framework to tackle data privacy issues of mobile devices compared to conventional Machine Learning (ML). Using Edge Servers (ESs) as intermediaries to perform model aggregation in proximity can reduce the transmission overhead, and it enables great potential in low-latency FL, where the hierarchical architecture of FL (HFL) has been attracted more attention. Designing a proper client selection policy can significantly improve training performance, and it has been widely investigated in conventional FL studies. However, to the best of our knowledge, systematic client selection policies have not yet been fully studied for HFL. In addition, client selection for HFL faces more challenges than conventional FL (e.g., the time-varying connection of client-ES pairs and the limited budget of the Network Operator (NO)). In this article, we investigate a client selection problem for HFL, where the NO learns the number of successful participating clients to improve training performance (i.e., select as many clients in each round) as well as under the limited budget on each ES. An online policy, called Context-aware Online Client Selection (COCS), is developed based on Contextual Combinatorial Multi-Armed Bandit (CC-MAB). COCS observes the side-information (context) of local computing and transmission of client-ES pairs and makes client selection decisions to maximize NO's utility given a limited budget. Theoretically, COCS achieves a sublinear regret compared to an Oracle policy on both strongly convex and non-convex HFL. Simulation results also support the efficiency of the proposed COCS policy on real-world datasets.

This paper studies a federated learning (FL) system, wheremultipleFL services co-exist in a wireless network and share common wireless resources. It fills the void of wireless resource allocation for multiple simultaneous FL services in the existing literature. Our method designs a two-level resource allocation framework comprisingintra-serviceresource allocation andinter-serviceresource allocation. The intra-service resource allocation problem aims to minimize the length of FL rounds by optimizing the bandwidth allocation among the clients of each FL service. Based on this, an inter-service resource allocation problem is further considered, which distributes bandwidth resources among multiple simultaneous FL services. We consider both cooperative and selfish providers of the FL services. For cooperative FL service providers, we design a distributed bandwidth allocation algorithm to optimize the overall performance of multiple FL services, meanwhile catering it to the fairness among FL services and the privacy of clients. For selfish FL service providers, a new auction scheme is designed with the FL service providers as the bidders and the network operator as the auctioneer. The designed auction scheme strikes a balance between the overall FL performance and fairness. Our simulation results show that the proposed algorithms outperform other benchmarks under various network conditions.

The momentous enabling of deep learning (DL)-powered mobile application is posing a soaring demand for computing resources that can hardly be satisfied by mobile devices. In this paper, we employ Edge Computing to deliver DL inference services to mobile users, where Deep Neural Networks (DNNs) are configured on edge servers, processing inference tasks received from mobile devices. A novel method called Adaptive DNN Ensemble (ADE) is proposed to enhance the performance of DL inference services. The core of ADE is the DNN ensemble technique which improves the stability and accuracy of DL inference. Due to the limited computing resources and service response deadline, ADE needs to judiciously determine DNNs to be included in the DNN ensemble, which poses a unique DNN ensemble selection problem. In addition, because DNNs exhibit performance variations for tasks with different features, DNN ensemble selection also aims to reconFigure DNN ensembles according to the feature of admitted tasks. We design an online learning algorithm, Contextual Combinatorial Multi-Armed Bandit (CC-MAB), to learn the DNN performance for tasks with different features. We rigorously prove that the proposed online learning algorithm is able to achieve asymptotic optimality. Experiments are carried out on an edge computing testbed to evaluate our method. Various implementation concerns, including memory usage, time complexity, and DNN switching cost, are considered. The results show that ADE outperforms other benchmarks in terms of inference accuracy and can provide real-time responses.

Recent breakthroughs in deep learning (DL) have led to the emergence of many intelligent mobile applications and services, but in the meanwhile also pose unprecedented computing challenges on resource-constrained mobile devices. This paper builds a collaborative deep inference system between a resource-constrained mobile device and a powerful edge server, aiming at joining the power of both on-device processing and computation offloading. The basic idea of this system is to partition a deep neural network (DNN) into a front-end part running on the mobile device and a back-end part running on the edge server, with the key challenge being how to locate the optimal partition point to minimize the end-to-end inference delay. Unlike existing efforts on DNN partitioning that rely heavily on a dedicated offline profiling stage to search for the optimal partition point, our system has a built-in online learning module, called Autodidactic Neurosurgeon (ANS), to automatically learn the optimal partition point on-the-fly. Therefore, ANS is able to closely follow the changes of the system environment by generating new knowledge for adaptive decision making. The core of ANS is a novel contextual bandit learning algorithm, called μLinUCB, which not only has provable theoretical learning performance guarantee but also is ultra-lightweight for easy real-world implementation. We implement our system on a video stream object detection testbed to validate the design of ANS and evaluate its performance. The experiments show that ANS significantly outperforms state-of-the-art benchmarks in terms of tracking system changes and reducing the end-to-end inference delay.

Edge computing (EC) platforms, which enable Application Service Providers (ASPs) to deploy applications in close proximity to users, are providing ultra-low latency and location-awareness to a rich portfolio of services. As monetary costs are incurred for renting computing resources on edge servers to enable service provisioning, ASP has to cautiously decide where to deploy the application and how much resources would be needed to deliver satisfactory performance. However, the service provisioning problem exhibits complex correlations with multifarious factors in EC systems, ranging from user behavior to computation offloading, which are difficult to be fully captured by mathematical modeling and also put off traditional machine learning techniques due to the induction of high-dimension state space. The recent success of deep learning (DL) underpins new tools for addressing our problem. While previous works provide valuable insights on applying DL techniques, e.g., distributed DL, deep reinforcement learning (DRL), and multi-agent DL, in EC systems, these techniques cannot solely handle the distributed and heterogeneous nature of EC systems. To address these limitations, we propose a novel framework based on multi-agent DRL, distributed neural network orchestration (N2O), and knowledge distilling. The multi-agent DRL enables edge servers to learn deep neural networks that shelve distinct features learned from local edge sites and hence caters to the heterogeneity of EC systems. N2O coordinates edge servers in a fully distributed manner toward a common goal of maximizing ASP’s reward. It requires only local communications during execution and provides provable performance guarantees. The knowledge distilling is further utilized to distill the N2O policy for reducing the communication overhead and stabilizing the decision-making. We also carry out systematic experiments to show the advantages of our method over state-of-the-art alternatives.

We revisit the traditional framework of wireless secret key generation, where two parties leverage the wireless channel randomness to establish a secret key. The essence in the framework is to quantify channel randomness into bit sequences for key generation. Conducting randomness tests on such bit sequences has been a common practice to provide the confidence to validate whether they are random. Interestingly, despite different settings in the tests, existing studies interpret the results the same: passing tests means that the bit sequences are indeed random. In this paper, we investigate how to properly test the wireless channel randomness to ensure enough security strength and key generation efficiency. In particular, we define an adversary model that leverages the imperfect randomness of the wireless channel to search the generated key, and create a guideline to set up randomness testing and privacy amplification to eliminate security loss and achieve efficient key generation rate. We use theoretical analysis and comprehensive experiments to reveal that common practice misuses randomness testing and privacy amplification: (i) no security insurance of key strength, (ii) low efficiency of key generation rate. After revision by our guideline, security loss can be eliminated and key generation rate can be increased significantly.

Mobile Edge Computing (MEC) pushes computing functionalities away from the centralized cloud to the proximity of data sources, thereby reducing service provision latency and saving backhaul network bandwidth. Although computation offloading for MEC systems has been extensively studied in the literature, service placement is an equally, if not more, important design topic of MEC, yet receives much less attention. Service placement refers to configuring the service platform and storing the related libraries/databases at the edge server, e.g., MEC-enabled Base Station (BS), which enables corresponding computation tasks to be executed. Due to the limited computing resource, the edge server can host only a small number of services and hence which services to host has to be judiciously decided to maximize the system performance. In this paper, we investigate collaborative service placement in MEC-enabled dense small cell networks. An efficient decentralized algorithm, called CSP (Collaborative Service Placement), is proposed where a network of small cell BSs optimize service placement decisions collaboratively to address a number of challenges in MEC systems, including service heterogeneity, spatial demand coupling, and decentralized coordination. CSP is developed based on parallel Gibbs sampling by exploiting the graph coloring on the small cell network. The algorithm significantly improves the time efficiency compared to conventional Gibbs sampling, yet guarantees provable convergence and optimality. CSP is further extended to work with selfish BSs, where BSs are allowed to choose “to cooperate” or “not to cooperate.” We employ coalitional game to investigate the strategic behaviors of selfish BSs and design a coalition formation scheme to form stable BS coalitions using merge-and-split rules. Simulations results show that CSP can effectively reduce edge system operational cost for both cooperative and selfish BSs.

This paper studies federated learning (FL) in a classic wireless network, where learning clients share a common wireless link to a coordinating server to perform federated model training using their local data. In such wireless federated learning networks (WFLNs), optimizing the learning performance depends crucially on how clients are selected and how bandwidth is allocated among the selected clients in every learning round, as both radio and client energy resources are limited. While existing works have made some attempts to allocate the limited wireless resources to optimize FL, they focus on the problem in individual learning rounds, overlooking an inherent yet critical feature of federated learning. This paper brings a new long-term perspective to resource allocation in WFLNs, realizing that learning rounds are not only temporally interdependent but also have varying significance towards the final learning outcome. To this end, we first design data-driven experiments to show that different temporal client selection patterns lead to considerably different learning performance. With the obtained insights, we formulate a stochastic optimization problem for joint client selection and bandwidth allocation under long-term client energy constraints, and develop a new algorithm that utilizes only currently available wireless channel information but can achieve long-term performance guarantee. Experiments show that our algorithm results in the desired temporal client selection pattern, is adaptive to changing network environments and far outperforms benchmarks that ignore the long-term effect of FL.

There is a growing interest in developing deep learning methods to solve many resource management problems in wireless edge computing systems where model-based designs are infeasible. While deep learning is known to be vulnerable to adversarial example attacks, the security risk of learningbased designs in the context of edge computing is not well understood. In this paper, we propose and study a new adversarial example attack, called stealthy interference attack (SIA), in deep reinforcement learning (DRL)-based edge computation offloading systems. In SIA, the attacker exerts a carefully determined level of interference signal to change the input states of the DRL-based policy, thereby fooling the mobile device in selecting a target and compromised edge server for computation offloading while evading detection. Simulation results demonstrate the effectiveness of SIA, and show that our algorithm outperforms existing adversarial machine learning algorithms in terms of a higher attack success probability and a lower power consumption.

To cope with the exploding mobile traffic in the fifth generation cellular network, the dense deployment of small cells and cognitive radios are two key technologies that significantly increase the network capacity and improve the spectrum utilization efficiency. Despite the desirable features, small cell cognitive radio networks (SCRNs) also face a higher risk of unauthorized spectrum access, which should not be overlooked. In this paper, we consider a passive monitoring system for SCRNs, which deploys sniffers for wireless traffic capture and network forensics, and study the optimal sniffer channel assignment (SCA) problem to maximize the monitoring performance. Unlike most existing SCA approaches that concentrate on user activity, we highlight the inherent error in wireless data capture (i.e. imperfect monitoring) due to the unreliable nature of wireless propagation, and propose an online-learning based algorithm called OSA (Online Sniffer-channel Assignment). OSA is a type of contextual combinatorial multi-armed bandit learning algorithm, which addresses key challenges in SCRN monitoring including the time- varying spectrum resource, imperfect monitoring, and uncertain network conditions. We theoretically prove that OSA has a sublinear learning regret bound and illustrate via simulations that OSA significantly outperforms benchmark solutions.

With the rapid development of the Internet-of-Things (IoT) networks, millions of IoT services provided through wireless networks are waiting for people’s exploration. Such a large number of heterogeneous IoT services produce huge amounts of data in almost real time, known asbig data, many of which cannot be measured or quantified. Hence, a recommended system that aims to deal with the unquantifiable big data is urgently needed. To solve the problem, we propose a novel quantile contextual tree-based multiarmed bandits algorithm to support the large-scale recommendation with both quantifiable and unquantifiable data. Furthermore, the high failure rate of communication has a serious influence on the recommendation accuracy of our system with the widely used D2D technology in today’s IoT network. To improve recommendation accuracy under the D2D communication, we take into account the feedback of historical service receivers and the historical successful delivery rate (SDP) of data transmission at the same time for the service recommendation system. We give theoretical analysis to prove a sublinear bound of the regret. Numerical experiments with tremendously large data sets show that we can balance the regret with the system time cost and guarantee a high SDP.

Content caching at the Internet edge using a network of wireless edge caching stations (ECSs) is recently considered as a key solution to alleviating the backhaul traffic burden and improving the quality of experience in 5G networks. This paper studies wireless edge caching systems with the following features: first, content files can be partitioned into many coded packets, which then can be cached in multiple ECSs for collaborative content delivery; second, the service provider (SP) deploys time-to-live cache at ECSs and each cached content file has an occupancy time that needs to be guaranteed; third, the content-to-be-cached arrives at the caching system following a stochastic process as users request new content over time. Unlike existing works that determine which content to cache, this paper focuses on how to distribute the coded packets of content-to-be-cached among the network of ECSs in order to reduce the content downloading time. A novel content placement strategy, called stochastic collaborative content placement is proposed based on Lyapunov techniques. The proposed algorithm makes content placement decisions using only currently available information without foreseeing future content arrivals, takes advantage of the spatial content popularity variation with coded caching, and achieves the provable close-to-optimal long-term caching performance. Simulations are carried out on a real-world YouTube video request trace and the results demonstrate a tremendous caching performance improvement against a variety of benchmark schemes.

Mobile Edge Computing (MEC) is delivering a rich portfolio of computation services to enable ultra-low latency and location-awareness for emerging mobile applications. However, the vulnerability of this new paradigm to potential security and privacy issues prevents mobile users from fully embracing its advantage. While various defensive strategies have been proposed to secure the connection between the end devices and edge servers, an equally important issue, the server-side risk is still under-investigated for most edge computing systems. To handle these server-side risks, a Risk-aware Computation Offloading (RCO) policy is proposed to distribute computation tasks safely among geographically distributed edge sites under server-side attacks. RCO takes into account the strategic behaviors of the potential attackers in the edge system and finds an appropriate balance between risk management and service delay reduction. The Bayesian Stackelberg game is employed to formulate the RCO problem, which describes an appropriate relation between the edge system (as a defender) and the attacker. In particular, the Bayesian Stackelberg game captures the uncertainty of attacker’s behavior and enables RCO to work even when the edge system does not know precisely the attacker that it is playing against. To facilitate the derivation of Stackelberg equilibria, two pruning rules, Heuristic Pruning (HP) and Branch-and-Bound (BaB), are proposed. HP prunes by analyzing the user demand distribution and attacker types, and BaB prunes by obtaining the tight upper/lower bound of edge system utility with the assist of disjunctive programming and Bender’s cut.

Recent years have witnessed deep neural networks (DNNs) become the de facto tool in many applications such as image classification and speech recognition. But significant unmet needs remain in performing DNN inference tasks on mobile devices. Although edge computing enables complex DNN inference tasks to be performed in close proximity to the mobile device, performance optimization requires a carefully designed synergy between the edge and the mobile device. Moreover, the confidentiality of uploaded data to the possibly untrusted edge server is of great concern. In this paper, we investigate the impact of DNN partitioning on the inference latency performance and the privacy risks in edge computing. Based on the obtained insights, we design an offloading strategy that adaptively partitions the DNN in varying network environments to make the optimal tradeoff between performance and privacy for battery-powered mobile devices. This strategy is designed under the learning-aided Lyapunov optimization framework and has a provable performance guarantee. Finally, we build a small- scale testbed to demonstrate the efficacy of the proposed offloading scheme.

Collaborative computing among peer mobile devices via device-to-device (D2D) links, a.k.a. D2D offloading, is a promising technology to enhance mobile computing performance and reduce core wireless network traffic. However, D2D offloading also creates new security risks as malware can relatively easily compromise mobile devices participating in D2D offloading and propagate across the entire network. In this paper, we build a new epidemic model to understand the malware propagation process in the D2D offloading-enabled network where mobile devices are strategically deciding their participation level. The system operator only indirectly controls their participation level via offering participation rewards. Based on this model, we further model the strategic interaction between the defender (i.e. the system operator) and the attacker (i.e. malware) as a zero-sum differential game. The existence of a saddle-point equilibrium is proved, and the optimal dynamic defender and attacker strategies are derived based on the Pontryagin's maximum principle. Numerical results validate the proposed model and show that the dynamic optimal strategies significantly improve the system utility compared with baseline strategies.

Vehicular Cloud Computing (VCC) is a new technological shift which exploits the computation and storage resources on vehicles for computational service provisioning. Spare onboard resources are pooled by a VCC operator, e.g. a roadside unit, to serve computational tasks using the vehicle-as-a-resource framework. This paper investigates timely service provisioning for deadline-constrained tasks in VCC systems by leveraging the task replication technique (i.e., allowing one task to be executed by vehicles). A learning-based algorithm, called DATEV (Deadline-Aware Task rEplication for Vehicular Cloud), is proposed to address the special issues in VCC systems including uncertainty of vehicle movements, volatile vehicle members, and large vehicle population. The proposed algorithm is developed based on a novel contextual-combinatorial multi-armed bandit learning framework. DATE-V is “ contextual ” because it utilizes side information (context) of vehicles and tasks to infer the completion probability of a task replication under random vehicle movements. DATE-V is “combinatorial” because it replicates the received task and sends task replications to multiple vehicles to guarantee the service timeliness. When learning with multi-armed bandit, DATE-V also addresses the practical concern of delayed feedbacks caused by the task transmission/computational delay in using VCC. We rigorously prove that our learning algorithm achieves a sublinear regret bound compared to an oracle algorithm that knows the exact completion probability of any task replications. Simulations are carried out based on real-world vehicle movement traces and the results show that DATE-V significantly outperforms benchmark solutions.

With the rapidly growing number of connected smart devices deployed and diverse services provided in the Internet of Things (IoT), service selection system, which discovers appropriate services for users, is becoming more and more important. However, challenges exist as a result of the highly heterogeneous environments, characteristics of various kinds of users and the expanding number of services offered by many service providers, which have promising applications in IoT. In the meantime, users' contexts (e.g., location, time, and surroundings), wildly utilized in the IoT scenario to better satisfy individuals' demands, raises privacy issues. To address these problems, we propose a privacy-preserving mobile edge computing (MEC) enabled context-aware service selection system over software defined networks (SDN) in IoT to provide suitable services for end users, where the edge nodes (ENs) cache and process information, acting as cooperative learners. Utilizing the users' feedback and the historical records monitored by the SDN-based network, our contextual online learning algorithm achieves high prediction accuracy. Besides, instead of considering them as individual items, we utilize a top-down cover tree structure to handle service data, which supports ever-increasing large-scale datasets and complex situations. We theoretically prove that the accumulative regret of our algorithm has a sublinear bound and our numerical results confirm that our algorithm can handle big data problems while achieving a balance between privacy-preserving level and service selection accuracy.

Shared edge computing platforms, which enable Application Service Providers (ASPs) to deploy applications in close proximity to mobile users are providing ultra-low latency and location-awareness to a rich portfolio of services. Though ubiquitous edge service provisioning, i.e., deploying the application at all possible edge sites, is always preferable, it is impractical due to often limited operational budget of ASPs. In this case, an ASP has to cautiously decide where to deploy the edge service and how much budget it is willing to use. A central issue here is that the service demand received by each edge site, which is the key factor of deploying benefit, is unknown to ASPs a priori. What's more complicated is that this demand pattern varies temporally and spatially across geographically distributed edge sites. In this paper, we investigate an edge resource rental problem where the ASP learns service demand patterns for individual edge sites while renting computation resource at these sites to host its applications for edge service provisioning. An online algorithm, called Context-aware Online Edge Resource Rental (COERR), is proposed based on the framework of Contextual Combinatorial Multi-armed Bandit (CC-MAB). COERR observes side-information (context) to learn the demand patterns of edge sites and decides rental decisions (including where to rent the computation resource and how much to rent) to maximize ASP's utility given a limited budget. COERR provides a provable performance achieving sublinear regret compared to an Oracle algorithm that knows exactly the expected service demand of edge sites. Experiments are carried out on a real-world dataset and the results show that COERR significantly outperforms other benchmarks.

Online video sharing (e.g., via YouTube or YouKu) has emerged as one of the most important services in the current Internet, where billions of videos on the cloud are awaiting exploration. Hence, a personalized video retrieval system is needed to help users find interesting videos from big data content. Two of the main challenges are to process the increasing amount of video big data and resolve the accompanying “cold start” issue efficiently. Another challenge is to satisfy the users’ need for personalized retrieval results, of which the accuracy is unknown. In this paper, we formulate the personalized video big data retrieval problem as an interaction between the user and the system via a stochastic process, not just a similarity matching, accuracy (feedback) model of the retrieval; introduce users’ real-time context into the retrieval system; and propose a general framework for this problem. By using a novelcontextualmultiarmed bandit-based algorithm to balance the accuracy and efficiency, we propose a context-based online big-data-oriented personalized video retrieval system. This system can support datasets that are dynamically increasing in size and has the property of cross-modal retrieval. Our approach provides accurate retrieval results withsublinearregret andlinearstorage complexity and significantly improves the learning speed. Furthermore, by learning for a cluster of similar contexts simultaneously, we can realize sublinear storage complexity with the same regret but slightly poorer performance on the “cold start” issue compared to the previous approach. We validate our theoretical results experimentally on a tremendously large dataset; the results demonstrate that the proposed algorithms outperform existing bandit-based online learning methods in terms of accuracy and efficiency and the adaptation from the bandit framework offers additional benefits.

The explosive growth of multimedia contents (MCs) in today's mobile social networks has pushed edge computing to face severe security and online big data-processing problems. On the one hand, the edge nodes (ENs) should help mobile users find, cache, and share MCs in the presence of an ever-increasing scale of multimedia big data. On the other hand, how to provide secure MC retrieval schemes to excludedishonest-and-maliciousuntrusted ENs and to prevent privacy breaches fromhonest-but-curiousENs and users is a challenging issue. To tackle these problems, we study the privacy-preserving and trustworthy MCs retrieval system to make personalized MC recommendations from ENs to users with big data support. In our framework, each EN is modeled as a distributed context-aware online learner. ENs collaborate to learn users’ preferences based on their contexts and previous behaviors and social intimacy. To support big data analytics, we establish an MC-cluster tree from top to the bottom to handle the dynamically varying cached MC datasets. A differentially private algorithm is proposed to preserve the data privacy among honest-but-curious ENs and users. To guarantee trustworthy edge computing, a trust evaluation mechanism is designed to evaluate the reliability of ENs. We further consider the structure of edge networks to improve the performance of our algorithm. Experimental results validate that our new framework can support increasing multimedia big datasets while striking a balance among privacy-preserving level, Trustworthy level, and caching MC prediction accuracy.

We consider the online shortest path routing (SPR) of a network with stochastically time varying link states under potential adversarial attacks. Due to the denial of service (DoS) attacks, the distributions of link states could be stochastic (benign) or adversarial at different temporal and spatial locations. Without any a priori, designing an adaptive and optimal DoS-proof SPR protocol to thwart all possible adversarial attacks is a very challenging issue. In this paper, we present the first such integral solution based on the multi-armed bandit (MAB) theory, where jamming is the adversarial strategy. By introducing a novel control parameter into the exploration phase for each link, a martingale inequality is applied in our formulated combinatorial adversarial MAB framework. The proposed algorithm could automatically detect the specific jammed and un-jammed links within a unified framework. As a result, the adaptive online SPR strategies with near-optimal learning performance in all possible regimes are obtained. Moreover, we propose the accelerated algorithms by multi-path route probing and cooperative learning among multiple sources, and study their implementation issues. Comparing to existing works, our algorithm has the respective 30.3% and 87.1% improvements of network delay for oblivious jamming and adaptive jamming given a typical learning period and a 81.5% improvement of learning duration under a specified network delay on average, while it enjoys almost the same performance without jamming. Lastly, the accelerated algorithms can achieve a maximal of 150.2% improvement in network delay and a 431.3% improvement in learning duration.

As one of most fascinating machine learning techniques, deep neural network (DNN) has demonstrated excellent performance in various intelligent tasks such as image classification. DNN achieves such performance, to a large extent, by performing expensive training over huge volumes of training data. To reduce the data storage and transfer overhead in smart resource-limited Internet-of-Thing (IoT) systems, effective data compression is a "must-have" feature before transferring real-time produced dataset for training or classification. While there have been many well-known image compression approaches (such as JPEG), we for the first time find that a human-visual based image compression approach such as JPEG compression is not an optimized solution for DNN systems, especially with high compression ratios. To this end, we develop an image compression framework tailored for DNN applications, named "DeepN-JPEG", to embrace the nature of deep cascaded information process mechanism of DNN architecture. Extensive experiments, based on "ImageNet" dataset with various state-of-the-art DNNs, show that "DeepN-JPEG" can achieve ∼ 3.5× higher compression rate over the popular JPEG solution while maintaining the same accuracy level for image recognition, demonstrating its great potential of storage and power efficiency in DNN-based smart IoT system design.

We study downlink transmission in a multi-band heterogeneous network comprising unmanned aerial vehicle (UAV) small base stations and ground-based dual mode mmWave small cells within the coverage area of a microwave (μW) macro base station. We formulate a two-layer optimization framework to simultaneously find efficient coverage radius for the UAVs and energy efficient radio resource management for the network, subject to minimum quality-of-service (QoS) and maximum transmission power constraints. The outer layer derives an optimal coverage radius/height for each UAV as a function of the maximum allowed path loss. The inner layer formulates an optimization problem to maximize the system energy efficiency (EE), defined as the ratio between the aggregate user data rate delivered by the system and its aggregate energy consumption (downlink transmission and circuit power). We demonstrate that at certain values of the target SINR τ introducing the UAV base stations doubles the EE. We also show that an increase in τ beyond an optimal EE point decreases the EE.

Mobile Edge Computing (MEC) (a.k.a. fog computing) has recently emerged to enable low-latency and location-aware data processing at the edge of mobile networks. Providing grid power supply in support of MEC, however, is costly and even infeasible, thus mandating on-site renewable energy as a major or even sole power supply in many scenarios. Nonetheless, the high intermittency and unpredictability of energy harvesting creates many new challenges of performing effective MEC. In this paper, we develop an algorithm called GLOBE that performs joint geographical load balancing (GLB) (for computation workload) and admission control (for communication data traffic), for optimizing the system performance of a network of MEC-enabled base stations. By leveraging the Lyapunov optimization with perturbation technique, GLOBE operates online without requiring future system information and addresses significant challenges caused by battery state dynamics and energy causality constraints. We prove that GLOBE achieves a close-to-optimal system performance compared to the offline algorithm that knows full future information, and present a critical tradeoff between battery capacity and system performance. Simulation results validate our analysis and demonstrate the superior performance of GLOBE compared to benchmark algorithms.

Mobile Edge Computing (MEC) pushes computing functionalities away from the centralized cloud to the network edge, thereby meeting the latency requirements of many emerging mobile applications and saving backhaul network bandwidth. Although many existing works have studied computation of-floading policies, service caching is an equally, if not more important, design topic of MEC, yet receives much less attention. Service caching refers to caching application services and their related databases/libraries in the edge server (e.g. MEC-enabled BS), thereby enabling corresponding computation tasks to be executed. Because only a small number of application services can be cached in resource-limited edge server at the same time, which services to cache has to be judiciously decided to maximize the edge computing performance. In this paper, we investigate the extremely compelling but much less studied problem of dynamic service caching in MEC-enabled dense cellular networks. We propose an efficient online algorithm, called OREO, which jointly optimizes dynamic service caching and task offloading to address a number of key challenges in MEC systems, including service heterogeneity, unknown system dynamics, spatial demand coupling and decentralized coordination. Our algorithm is developed based on Lyapunov optimization and Gibbs sampling, works online without requiring future information, and achieves provable close-to-optimal performance. Simulation results show that our algorithm can effectively reduce computation latency for end users while keeping energy consumption low.

Caching at the network edge devices such as wireless caching stations (WCS) is a key technology in the 5G network. The spatial-temporal diversity of content popularity requires different content to be cached in different WCSs and periodically updated to adapt to temporal changes. In this paper, we study how the popularity drifting speed affects the number of required broadcast transmissions by the MBS and then design coded transmission schemes by leveraging the broadcast advantage under the index coding framework. The key idea is that files already cached in WCSs, which although may be currently unpopular, can serve as side information to facilitate coded broadcast transmission for cache updating. Our algorithm extends existing index coding-based schemes from a single-request scenario to a multiple-request scenario via a “dynamic coloring” approach. Simulation results indicate that a significant bandwidth saving can be achieved by adopting our scheme.

In this paper, we study the stochastic contextual combinatorial multi-armed bandit (CC-MAB) framework that is tailored for volatile arms and submodular reward functions. CC-MAB inherits properties from both contextual bandit and combinatorial bandit: it aims to select a set of arms in each round based on the side information (a.k.a. context) associated with the arms. By ``volatile arms'', we mean that the available arms to select from in each round may change; and by ``submodular rewards'', we mean that the total reward achieved by selected arms is not a simple sum of individual rewards but demonstrates a feature of diminishing returns determined by the relations between selected arms (e.g. relevance and redundancy). Volatile arms and submodular rewards are often seen in many real-world applications, e.g. recommender systems and crowdsourcing, in which multi-armed bandit (MAB) based strategies are extensively applied. Although there exist works that investigate these issues separately based on standard MAB, jointly considering all these issues in a single MAB problem requires very different algorithm design and regret analysis. Our algorithm CC-MAB provides an online decision-making policy in a contextual and combinatorial bandit setting and effectively addresses the issues raised by volatile arms and submodular reward functions. The proposed algorithm is proved to achieve $O(cT^{\frac{2\alpha+D}{3\alpha + D}}\log(T))$ regret after a span of $T$ rounds. The performance of CC-MAB is evaluated by experiments conducted on a real-world crowdsourcing dataset, and the result shows that our algorithm outperforms the prior art.

Industrial fog computing deploys various industrial services, such as automatic monitoring/control and imminent failure detection, at the fog nodes (FNs) to improve the performance of industrial systems. Much effort has been made in the literature on the design of fog network architecture and computation offloading. This paper studies an equally important but much less investigated problem of service hosting where FNs are adaptively configured to host services for sensor nodes (SNs), thereby enabling corresponding tasks to be executed by the FNs. The problem of service hosting emerges because of the limited computational and storage resources at FNs, which limit the number of different types of services that can be hosted by an FN at the same time. Considering the variability of service demand in both temporal and spatial dimensions, when, where, and which services to host have to be judiciously decided to maximize the utility of the fog computing network. Our proposed fog configuration strategies are tailored to battery-powered FNs. The limited battery capacity of FNs creates a long-term energy budget constraint that significantly complicates the fog configuration problem as it introduces temporal coupling of decision making across the timeline. To address all these challenges, we propose an online distributed algorithm, called adaptive fog configuration (AFC), based on Lyapunov optimization and parallel Gibbs sampling. AFC jointly optimizes service hosting and task admission decisions, requiring only currently available system information while guaranteeing close-to-optimal performance compared to an oracle algorithm with full future information.

Computation offloading via device-to-device (D2D) communication, or D2D offloading, can enhance mobile computing performance by exploiting spare computing resources of nearby user devices. The success of D2D offloading relies on user participation in collaborative service provisioning, which incurs extra costs to users providing the service, thus mandating an incentive mechanism that can compensate for these costs. Although incentive mechanism design has been intensively studied in the literature, this paper considers a much more challenging yet less investigated problem in which selfish users are also facing interdependent security risks, such as infectious proximity-based attacks. Security cost is significantly different in nature from conventional service provisioning costs such as energy consumption because security risks often depend on the collective behavior of all users. To this end, we build a novel mathematical framework by leveraging the combined power of game theory and epidemic theory to investigate the interplay between user incentives and interdependent security risks in D2D offloading, thereby enabling the design of security-aware incentive mechanisms. Our analysis discovers an interesting “less is more” phenomenon: although giving users more incentives promotes more participation, it may harm the network operator’s utility. This is because too much participation may foster persistent security risks, and as a result, the effective participation level does not improve.

Shared edge computing platforms deployed at the radio access network are expected to significantly improve the quality-of-service delivered by application service providers (ASPs) in a flexible and economic way. However, placing edge service in every possible edge site by an ASP is practically infeasible due to the ASP’s prohibitive budget requirement. In this paper, we investigate the edge service placement problem of an ASP under a limited budget, where the ASP dynamically rents computing/storage resources in edge sites to host its applications in close proximity to end users. Since the benefit of placing edge service in a specific site is usually unknown to the ASPa priori, optimal placement decisions must be made while learning this benefit. We pose this problem as a novel combinatorial contextual bandit learning problem. It is “combinatorial” because only a limited number of edge sites can be rented to provide the edge service given the ASP’s budget. It is “contextual” because we utilize user context information to enable finer-grained learning and decision-making. To solve this problem and optimize the edge computing performance, we propose SEEN, a Spatial-temporal Edge sErvice placemeNt algorithm. Furthermore, SEEN is extended to scenarios with overlapping service coverage by incorporating a disjunctively constrained knapsack problem. In both cases, we prove that our algorithm achieves a sublinear regret bound when it is compared with an Oracle algorithm that knows the exact benefit information. Simulations are carried out on a real-world dataset, whose results show that SEEN significantly outperforms benchmark solutions.

Accurately predicting students' future performance based on their tracked academic records in college programs is crucial for effectively carrying out necessary pedagogical interventions to ensure students' on-time graduation. Although there is a rich literature on predicting student performance in solving problems and studying courses using data-driven approaches, predicting student performance in completing college programs is much less studied and faces new challenges, mainly due to the diversity of courses selected by students and the requirement of continuous tracking and incorporation of students' evolving progresses. In this paper, we develop a novel algorithm that enables progressive prediction of students' performance by adapting ensemble learning techniques and utilizing education-specific domain knowledge. We prove its prediction performance guarantee and show its performance improvement against benchmark algorithms on a real-world student dataset from UCLA.

The dense deployment of small-cell base stations (SBSs) endowed with cloud-like computing capabilities paves the way for pervasive mobile edge computing (MEC), enabling ultra-low latency and location-awareness for emerging mobile applications. To handle spatially imbalanced computation workloads in the network, cooperation among SBSs via peer offloading is essential to avoid large latency at overloaded SBSs and provide high quality of service to end users. However, performing effective peer offloading faces many challenges due to uncertainties of the system dynamics, limited energy budget committed by SBS owners and co- provisioning of radio access and computing services. This paper develops a novel online SBS peer offloading framework, called OPEN, by leveraging the Lyapunov technique, in order to maximize the long-term system performance while keeping the energy consumption of SBSs below individual long-term energy budget. OPEN works online without requiring future information of system dynamics, yet provides provably near-optimal performance compared to the oracle solution with complete future information. Extensive simulations are carried out and show that proposed algorithm dramatically improves the performance of edge computing system.

Merging Mobile Edge Computing (MEC), which is an emerging paradigm to meet the increasing computation demands from mobile devices, with the dense deployment of Base Stations (BSs), is foreseen as a key step towards the next generation mobile networks. However, new challenges arise for designing energy efficient networks since radio access resources and computing resources of BSs have to be jointly managed, and yet they are complexly coupled with traffic in both spatial and temporal domains. In this paper, we address the challenge of incorporating MEC into dense cellular networks, and propose an efficient online algorithm, called ENGINE (ENerGy constrained offloadINg and slEeping) which makes joint computation offloading and BS sleeping decisions in order to maximize the quality of service while keeping the energy consumption low. Our algorithm leverages Lyapunov optimization technique, works online and achieves a close-to-optimal performance without using future information. Our simulation results show that our algorithm can effectively reduce energy consumption while guaranteeing quality of service for users.

Merging mobile edge computing with the dense deployment of small cell base stations promises enormous benefits such as a real proximity, ultra-low latency access to cloud functionalities. However, the envisioned integration creates many new challenges and one of the most significant is mobility management, which is becoming a key bottleneck to the overall system performance. Simply applying existing solutions leads to poor performance due to the highly overlapped coverage areas of multiple base stations in the proximity of the user and the co-provisioning of radio access and computing services. In this paper, we develop a novel user-centric mobility management scheme, leveraging Lyapunov optimization and multi-armed bandits theories, in order to maximize the edge computation performance for the user while keeping the user's communication energy consumption below a constraint. The proposed scheme effectively handles the uncertainties present at multiple levels in the system and provides both short-term and long-term performance guarantee. Simulation results show that our proposed scheme can significantly improve the computation performance (compared to state of the art) while satisfying the communication energy constraint.

Merging mobile edge computing (MEC) functionality with the dense deployment of base stations (BSs) provides enormous benefits such as a real proximity, low latency access to computing resources. However, the envisioned integration creates many new challenges, among which mobility management (MM) is a critical one. Simply applying existing radio access-oriented MM schemes leads to poor performance mainly due to the co-provisioning of radio access and computing services of the MEC-enabled BSs. In this paper, we develop a novel user-centric energy-aware mobility management (EMM) scheme, in order to optimize the delay due to both radio access and computation, under the long-term energy consumption constraint of the user. Based on Lyapunov optimization and multi-armed bandit theories, EMM works in an online fashion without future system state information, and effectively handles the imperfect system state information. Theoretical analysis explicitly takes radio handover and computation migration cost into consideration and proves a bounded deviation on both the delay performance and energy consumption compared with the oracle solution with exact and complete future system information. The proposed algorithm also effectively handles the scenario in which candidate BSs randomly switch ON/OFF during the offloading process of a task. Simulations show that the proposed algorithms can achieve close-to-optimal delay performance while satisfying the user energy consumption constraint.

Many emerging Big Data applications involve real- time classification in which data instances arriving sequentially over time need to be classified based on their feature vectors. A common and implicit assumption in existing works is that the features become available instantly with the instance and simultaneously with each other, which, however, rarely holds in practice. Instead, features of an instance may experience various random delays to be available. In such scenarios, an important trade-off emerges between accurate classification and timely classification. In this paper, we provide a first formulation of this important problem and propose efficient online algorithms, namely DAlay-aware Real-time Classification (DARC) algorithms, that maximize the classification accuracy given an average classification delay constraint. The algorithms are developed based on the Lyapunov stochastic optimization technique which provides strong performance guarantee. Numerical results on an intrusion detection dataset are provided to show the effectiveness of the proposed algorithm.

Mobile edge computing (a.k.a. fog computing) has recently emerged to enable in-situ processing of delay-sensitive applications at the edge of mobile networks. Providing grid power supply in support of mobile edge computing, however, is costly and even infeasible (in certain rugged or under-developed areas), thus mandating on-site renewable energy as a major or even sole power supply in increasingly many scenarios. Nonetheless, the high intermittency and unpredictability of renewable energy make it very challenging to deliver a high quality of service to users in renewable-powered mobile edge computing systems. In this paper, we address the challenge of incorporating renewables into mobile edge computing and propose an efficient reinforcement learning-based resource management algorithm, which learns on-the-fly the optimal policy of dynamic workload offloading (to centralized cloud) and edge server provisioning to minimize the long-term system cost (including both service delay and operational cost). Our online learning algorithm uses a decomposition of the (offline) value iteration and (online) reinforcement learning, thus achieving a significant improvement of learning rate and run- time performance when compared to standard reinforcement learning algorithms such as Q- learning.

This paper presents a novel cache replacement method — Popularity-Driven Content Caching (PopCaching). PopCaching learns the popularity of content and uses it to determine which content it should store and which it should evict from the cache. Popularity is learned in an online fashion, requires no training phase and hence, it is more responsive to continuously changing trends of content popularity. We prove that the learning regret of PopCaching (i.e., the gap between the hit rate achieved by PopCaching and that by the optimal caching policy with hindsight) is sublinear in the number of content requests. Therefore, PopCaching converges fast and asymptotically achieves the optimal cache hit rate. We further demonstrate the effectiveness of PopCaching by applying it to a movie.douban.com dataset that contains over 38 million requests. Our results show significant cache hit rate lift compared to existing algorithms, and the improvements can exceed 40% when the cache capacity is limited. In addition, PopCaching has low complexity.

Clinicians need to routinely make management decisions about patients who are at risk for a disease such as breast cancer. This paper presents a novel clinical decision support tool that is capable of helping physicians make diagnostic decisions. We apply this support system to improve the specificity of breast cancer screening and diagnosis. The system utilizes clinical context (e.g., demographics, medical history) to minimize the false positive rates while avoiding false negatives. An online contextual learning algorithm is used to update the diagnostic strategy presented to the physicians over time. We analytically evaluate the diagnostic performance loss of the proposed algorithm, in which the true patient distribution is not known and needs to be learned, as compared with the optimal strategy where all information is assumed known, and prove that the false positive rate of the proposed learning algorithm asymptotically converges to the optimum. In addition, our algorithm also has the important merit that it can provide individualized confidence estimates about the accuracy of the diagnosis recommendation. Moreover, the relevancy of contextual features is assessed, enabling the approach to identify specific contextual features that provide the most value of information in reducing diagnostic errors. Experiments were conducted using patient data collected at a large academic medical center. Our proposed approach outperforms the current clinical practice by 36% in terms of false positive rate given a 2% false negative rate.

We consider a cellular network where mobile transceiver devices that are owned by self-interested users are incentivized to cooperate with each other using tokens, which they exchange electronically to “buy” and “sell” downlink relay services, thereby increasing the network's capacity compared to a network that only supports base station-to-device (B2D) communications. We investigate how an individual device in the network can learn its optimal cooperation policyonline, which it uses to decide whether or not to provide downlink relay services for other devices in exchange for tokens. We propose a supervised learning algorithm that devices can deploy to learn their optimal cooperation strategies online given their experienced network environment. We then systematically evaluate the learning algorithm in various deployment scenarios. Our simulation results suggest that devices have the greatest incentive to cooperate when the network contains (i) many devices with high energy budgets for relaying, (ii) many highly mobile users (e.g., users in motor vehicles), and (iii) neither too few nor too many tokens. Additionally, within the token system, self-interested devices can effectively learn to cooperate online, and achieve up to 20 percent throughput gains on average compared to B2D communications alone, all while selfishly maximizing their own utilities.

This paper presents Trend-Caching, a novel cache replacement method that optimizes cache performance according to the trends of video content. Trend-Caching explicitly learns the popularity trend of video content and uses it to determine which video it should store and which it should evict from the cache. Popularity is learned in an online fashion and requires no training phase, hence it is more responsive to continuously changing trends of videos. We prove that the learning regret of Trend-Caching (i.e., the gap between the hit rate achieved by Trend-Caching and that by the optimal caching policy with hindsight) is sublinear in the number of video requests, thereby guaranteeing both fast convergence and asymptotically optimal cache hit rate. We further validate the effectiveness of Trend-Caching by applying it to a movie.douban.com dataset that contains over 38 million requests. Our results show significant cache hit rate lift compared to existing algorithms, and the improvements can exceed 40% when the cache capacity is limited. Furthermore, Trend-Caching has low complexity.

To increase efficacy in traditional classroom courses as well as in Massive Open Online Courses (MOOCs), automated systems supporting the instructor are needed. One important problem is to automatically detect students that are going to do poorly in a course early enough to be able to take remedial actions. This paper proposes an algorithm that predicts the final grade of each student in a class. It issues a prediction for each student individually, when the expected accuracy of the prediction is sufficient. The algorithm learns online what is the optimal prediction and time to issue a prediction based on past history of students' performance in a course. We derive demonstrate the performance of our algorithm on a dataset obtained based on the performance of approximately 700 undergraduate students who have taken an introductory digital signal processing over the past 7 years. Using data obtained from a pilot course, our methodology suggests that it is effective to perform early in-class assessments such as quizzes, which result in timely performance prediction for each student, thereby enabling timely interventions by the instructor (at the student or class level) when necessary.

This paper presents Pop-Forecast, a systematic method for accurately forecasting the popularity of videos promoted through social networks. Pop-Forecast aims to optimize the forecasting accuracy and the timeliness with which forecasts are issued, by explicitly taking into account the dynamic propagation of videos in social networks. The forecasting is performed online and requires no training phase or a priori knowledge. We analytically bound the performance loss of Pop-Forecast as compared to that obtained by an omniscient oracle and prove that the bound is sublinear in the number of video arrivals, thereby guaranteeing its fast rate of convergence as well as its asymptotic convergence to the optimal performance. We validate the performance of Pop-Forecast through extensive experiments using real-world data traces collected from the videos shared in RenRen, one of the largest online social networks in China. These experiments show that our proposed method outperforms existing approaches for popularity prediction (which do not take into account the propagation in social network) by more than 30% in terms of prediction rewards.

Electronic tokens have been successfully used as incentive mechanisms to stimulate self-interested network nodes to relay other nodes' traffic. In other words, tokens are paid tobuy transmission(relaying) services. In this work, we propose a novel distributed token exchange framework, which can be usedin heterogeneous small cell networks to successfully mitigate interference among the self-interested users. Contrary to the traditional role of buying transmission, tokens are exchanged between users tobuy silence. Heterogeneity poses unique challenges for interference mitigation, which are difficult to handle with previous solutions but can be effectively tackled with the proposed token design. This paper focuses on the rigorous design of the optimal token scheme that minimizes the system outage probability. We first analyze the optimal strategies of individual users, which only consider their own utility maximization and do not care about the system-wise performance. We prove that under some mild conditions the optimal strategy has a simple threshold structure. We then analytically derive the optimal token supply that minimizes the network outage probability. Analysis shows that even if each user adopts the optimal strategy that only maximizes its own utility, a careful token system design can lead to a significant overall network performance improvement. Simulation results show that not only does the proposed token system design greatly improve the network outage probability, it also improves the overall network QoS, particularly when the deployment density is high.

In many systems, agents interact repeatedly with each other over an exogenously determined network and need to cooperate with each other by producing and sharing valuable knowledge or information with the agents with which they are connected. However, producing and sharing information can be costly for the agents themselves, while providing no direct immediate benefit to them. Hence, there are incentives for individual agents to shirk rather than to work—to free ride on the information production and sharing of other agents rather than to produce information themselves. In this paper, we develop a systematic framework for designing rating systems aimed at promoting efficient production and sharing in these networks, thereby significantly improving the social welfare (i.e., sum utility of agents) of such networks. The schemes proposed operated effectively even in settings where monitoring of agent behavior is subject to significant errors. In many scenarios our schemes achieve maximum social welfare; in others, we prove that optimal schemes necessarily fall short of maximum social welfare due to imperfect monitoring. The distinction between these scenarios arises from the tension between the social value of producing for others and the strategic value of withholding production. In some scenarios, the optimal scheme allows that less-productive agents shirk (not produce); this creates the largest incentives for more-productive agents to work at the socially-desired level. We establish conditions under which recommending “work” to all agents is the optimal strategy and develop low-complexity algorithms to determine the optimal strategy in general settings for arbitrary information sharing networks.

Electronic tokens have been proved as an effective incentive scheme in stimulating self-interested network nodes to transmit other nodes' traffic. In other words, tokens are paid to buy transmission. In this work, we propose a novel token framework in a distributed small cell network and design the token system for improved interference mitigation. Contrary to the traditional role of tokens for buying transmission, they are exchanged between users to buy "silence". We focus on designing the optimal token system that minimizes the system outage probability. We first analyze the optimal strategies of individual users, which only consider their own utility maximization and do not care about the system-wise performance. We show that under some mild conditions the optimal strategy has a simple threshold structure. We then analytically derive the optimal token supply that minimizes the network outage probability. Simulation results show that not only does the proposed token system design greatly improve the network outage probability (by up to 75%), it also improves the overall small cell network QoS, particularly when the deployment density is high.

Enabling accurate and low-cost classification of a range of motion activities is of significant importance for wireless health through body worn inertial sensors and smartphones, due to the need by healthcare and fitness professonals to monitor exercises for quality and compliance. This paper proposes a novel contextual multi-armed bandits approach for large-scale activity classification. The proposed method is able to address the unique challenges arising from scaling, lack of training data and adaptation by melding context augmentation and continuous online learning into traditional activity classification. We rigorously characterize the performance of the proposed learning algorithm and prove that the learning regret (i.e. reward loss) is sublinear in time, thereby ensuring fast convergence to the optimal reward as well as providing short-term performance guarantees. Our experiments show that the proposed algorithm outperforms existing algorithms in terms of both providing higher classification accuracy as well as lower energy consumption.

For many networks (e.g. opinion consensus, cooperative estimation, distributed learning and adaptation etc.) to proliferate and efficiently operate, the participating agents need to collaborate with each other by repeatedly sharing information which is often costly while brings no direct immediate benefit for the agents. In this paper, we develop a systematic framework for designing distributed rating protocols aimed at incentivizing the strategic agents to collaborate with each other by sharing information. The proposed incentive protocols exploit the ongoing nature of the agents' interactions to assign ratings and through them, determine future rewards and punishments through social reciprocation. Unlike existing rating protocols, the proposed protocol operates in a distributed manner, and takes into consideration the underlying interconnectivity of agents as well as their heterogeneity. We prove that in many deployment scenarios adopting the proposed rating protocols achieves full efficiency (i.e. price of anarchy is one) even with strategic agents.

Due to the high bandwidth requirements and stringent delay constraints of multi-user wireless video transmission applications, ensuring that all video senders have sufficient transmission opportunities to use before their delay deadlines expire is a longstanding research problem. We propose a novel solution that addresses this problem without assuming detailed packet-level knowledge, which is unavailable at resource allocation time (i.e. prior to the actual compression and transmission). Instead, we translate the transmission delay deadlines of each sender's video packets into a monotonically-decreasing weight distribution within the considered time horizon. Higher weights are assigned to the slots that have higher probability for deadline-abiding delivery. Given the sets of weights of the senders' video streams, we propose the low-complexity Delay-Aware Resource Allocation (DARA) approach to compute the optimal slot allocation policy that maximizes the deadline-abiding delivery of all senders. A unique characteristic of the DARA approach is that it yields a non-stationary slot allocation policy that depends on the allocation of previous slots. This is in contrast with all existing slot allocation policies such as round-robin or rate-adaptive round-robin policies, which are stationary because the allocation of the current slot does not depend on the allocation of previous slots. We prove that the DARA approach is optimal for weight distributions that are exponentially decreasing in time. We further implement our framework for real-time video streaming in wireless personal area networks that are gaining significant traction within the new Internet-of-Things (IoT) paradigm. For multiple surveillance videos encoded with H.264/AVC and streamed via the 6tisch framework that simulates the IoT-oriented IEEE 802.15.4e TSCH medium access control, our solution is shown to be the only one that ensures all video bitstreams are delivered with acceptable quality in a deadline-abiding manner.

The radio spectrum is a scarce resource. Cognitive radio stretches this resource by enabling secondary stations to operate in portions of the spectrum that are reserved for primary stations but not currently used by the primary stations. As it is whenever stations share resources, coordination is a central issue in cognitive radio networks: absent coordination, there may be collision, congestion or interference, with concomitant loss of performance. Cognitive radio networks require coordination of secondary stations with primary stations (so that secondary stations should not interfere with primary stations) and of secondary stations with each other. Coordination in this setting is especially challenging because of the various types of sensing errors. This paper proposes novel protocols that enable secondary stations to learn and teach with the goal of coordinating to achieve a round-robin Time Division Multiple Access (TDMA) schedule. These protocols are completely distributed (requiring neither central control nor the exchange of any control messages), fast (with speeds exceeding those of existing protocols), efficient (in terms of throughput and delay) and scalable. The protocols proposed rely on cooperative learning, exploiting the ability of stations to learn from and condition on their own histories while simultaneously teaching other stations about these histories. Analytic results and simulations illustrate the power of these protocols.

Coordination is a central problem whenever stations (or nodes or users) share resources across a network. In the absence of coordination, there will be collision, congestion or interference, with concomitant loss of performance. This paper proposes new protocols, which we call perfect coordination (PC) protocols, that solve the coordination problem. PC protocols are completely distributed (requiring neither central control nor the exchange of any control messages), fast (with speeds comparable to those of any existing protocols), fully efficient (achieving perfect coordination, with no collisions and no gaps) and require minimal feedback. PC protocols rely heavily on learning, exploiting the possibility to use both actions and silence as messages and the ability of stations to learn from their own histories while simultaneously enabling the learning of other stations. PC protocols can be formulated as finite automata and implemented using currently existing technology (e.g., wireless cards). Simulations show that, in a variety of deployment scenarios, PC protocols outperform existing state-of-the-art protocols - despite requiring much less feedback.

Networked agents often share security risks but lack the incentive to make (sufficient) security investments if the cost exceeds their own benefit even though doing that would be socially beneficial. In this paper, we develop a systematic and rigorous framework based on rating systems for analyzing and significantly improving the mutual security of a network of agents that interact frequently over a long period of time. When designing the optimal rating systems, we explicitly consider that monitoring the agents' investment actions is imperfect and the heterogeneity of agents in terms of both generated traffic and underlying connectivity. Our analysis shows how the optimal rating system design should adapt to different monitoring and connectivity conditions. Even though this paper considers a simplified model of the networked agents' security, our analysis provides important and useful insights for designing rating systems that can significantly improve the mutual security of real networks in a variety of practical scenarios.

This paper proposes a novel framework for incentivizing self-interested transceivers operating in autonomic wireless networks to provide relaying services to other transceivers in exchange for tokens. Tokens represent a simple internal currency which can be used by the transceivers in a network to exchange services. Our emphasis in this paper is on developing optimal designs for the token system, which maximize the system efficiency, i.e. the probability that the relay transmission will be executed by transceivers whenever they are requested to provide such services. Particularly, we prove that the efficiency of the relay network heavily depends on issuing the proper amount of tokens rather than an arbitrary amount. First, we study the transceivers' optimal strategies (i.e. the strategies that maximize the transceivers' own utilities) using the formalism of repeated games. We prove that these strategies exhibit a simple threshold structure. We also prove that the threshold is unique given transmission costs. Second, we determine the optimal token amount which needs to be introduced in the relay system to maximize the overall relay network efficiency. This amount needs to be neither too small (since a too small amount leads to a small relaying service request probability) nor too large (since a too large amount leads to a small relaying service provision probability) and depends on the threshold strategy that the self-interested transceivers adopt. We subsequently develop an efficient algorithm which is able to determine, depending on the network characteristics, the threshold to be implemented by the optimal strategies and the optimal token amount. Finally, simulation results show the effectiveness of our token system design in providing incentives for cooperation among self-interested relays in autonomic wireless relay networks.

Information exchange systems, such as BitTorrent, Yahoo Answers, Yelp, Amazon Mechanical Turk, differ in many ways, but all share a common vulnerability to selfish behavior and free-riding. In this paper, we build incentives schemes based on social norms. Social norms prescribe a social strategy for the agents in the system to follow and deploy reputation schemes to reward or penalize agents depending on whether they follow or deviate from the prescribed strategy when selecting actions. Because agents in these systems often have only limited capability to observe the global system information, e.g. the reputation distribution of the agents participating in the system, their beliefs about the reputation distribution are heterogeneous and biased. Such belief heterogeneity causes a positive fraction of agents to not follow the social strategy. In such practical scenarios, the standard equilibrium analysis deployed in the economics literature is no longer directly applicable and hence, the system design needs to consider these differences. To investigate how the system designs need to change, we focus on a simple social norm with binary reputation labels but allow adjusting the punishment severity through randomization. First, we model the belief heterogeneity using a suitable Bayesian belief function. Next, we formalize the agents' optimal decision problems and derive in which scenarios they follow the prescribed social strategy. Then we study how the system state is determined by the agents' strategic behavior. We are particularly interested in the robust equilibrium where the system state becomes invariant when all agents strategically optimize their decisions. By rigorously studying two specific cases where agents' belief distribution is constant or is linearly influenced by the true reputation distribution, we prove that the optimal reputation update rule is to choose the mildest possible punishment. This result is further confirmed for more sophisticated belief influences in simulations. In conclusion, our proposed design framework enables the development of optimal social norms for various deployment scenarios with limited observations.

We consider subcarrier assignment and power allocation in OFDMA wireless mesh networks. Traditional full spatial reuse increases bandwidth efficiency but ignores multiuser diversity in the multi-hop network. Our method enables fractional spatial reuse with which multiuser diversity can also be exploited. The original optimization problem is decomposed into three tractable subproblems. First, subcarrier numbers on each link are decided according to end-to-end requirement and node power constraint. Then a novel link grouping method is proposed to utilize fractional spatial reuse in the network. Finally, a tabu-based subcarrier assignment algorithms is designed to assign subcarriers to groups to exploit multiuser diversity. Performance is evaluated under various network sizes to investigate the impact of spatial reuse and simulation results show our proposed scheme achieves multiuser diversity in spatial reuse scenarios.