Search

In multiuser communication systems, user scheduling and beamforming (US-BF) design are two fundamental problems that are usually studied separately in the existing literature. In this work, we focus on the joint US-BF design with the goal of maximizing the set cardinality of scheduled users, which is computationally challenging due to the non-convex objective function and the coupled constraints with discrete-continuous variables. To tackle these difficulties, a successive convex approximation based US-BF (SCA-USBF) optimization algorithm is firstly proposed. Then, inspired by wireless intelligent communication, a graph neural network based joint US-BF (J-USBF) learning algorithm is developed by combining the joint US and power allocation network model with the BF analytical solution. The effectiveness of SCA-USBF and J-USBF is verified by various numerical results, the latter achieves close performance and higher computational efficiency. Furthermore, the proposed J-USBF also enjoys the generalizability in dynamic wireless network scenarios., Comment: 31 pages, 9 figures, submit to IEEE Transactions on Wireless Communications

With the proliferation of versatile mobile applications, offloading compute-intensive tasks to the MEC/Cloud becomes a dramatic technique due to the limited resources and high user experience requirements at mobile devices. However, most existing works design their task offloading schemes without considering the dependence of tasks and the orchestration of the MEC and Cloud, and thus may limit the system performance. In this paper, we propose a dependent task offloading framework for multiple mobile applications, named COFE, where mobile devices can offload their compute-intensive tasks with dependent constraints to the MEC-Cloud system. It can assign the offloaded tasks to the MEC and Cloud adaptively to improve the user experience. Based on COFE, we formulate the task offloading problem as an average makespan minimization problem, which is proved to be NP-hard. Then, we propose a heuristic ranking-based algorithm to assign the offloaded tasks according to their bottom levels. Theoretical analysis proves the stability of the system under the proposed algorithm and extensive simulations validate that the proposed algorithm can significantly reduce the average makespan and deadline violation probabilities of offloaded applications.

User scheduling and beamforming design are two crucial yet coupled topics for wireless communication systems. They are usually optimized separately with conventional optimization methods. In this paper, a novel cross-layer optimization problem is considered, namely, the user scheduling and beamforming are jointly discussed subjecting to the requirement of per-user quality of service (QoS) and the maximum allowable transmit power for multicell multiuser joint transmission networks. To achieve the goal, a mixed discrete-continue variables combinational optimization problem is investigated with aiming at maximizing the sum rate of the communication system. To circumvent the original non-convex problem with dynamic solution space, we first transform it into a 0-1 integer and continue variables optimization problem, and then obtain a tractable form with continuous variables by exploiting the characteristics of 0-1 constraint. Finally, the scheduled users and the optimized beamforming vectors are simultaneously calculated by an alternating optimization algorithm. We also theoretically prove that the base stations allocate zero power to the unscheduled users. Furthermore, two heuristic optimization algorithms are proposed respectively based on brute-force search and greedy search. Numerical results validate the effectiveness of our proposed methods, and the optimization approach gets relatively balanced results compared with the other two approaches., Comment: 28 pages, 6 figures, submitted to IEEE Transactions on Communications, 2022

Differential privacy (DP) has gained popularity in truth discovery recently due to its strong privacy guarantee. However, existing DP mechanisms for streaming data publication are not suitable for truth discovery as they fail to consider the different reliabilities of individuals, while the DP-based approaches for truth discovery are not suitable for streaming data because they ignore the correlations between truths over time. To solve this problem, we propose an edge computing based privacy-preserving truth discovery mechanism, PrivSTD, for streaming crowdsourced data to realize high accuracy of discovered truth while protecting the privacy of workers. Specifically, edge servers are introduced between the untrusted cloud server and workers to securely calculate the local truths and workers reliabilities. A truth-dependent budget recycle mechanism is designed for each edge server to adaptively determine the perturbed timestamp and allocate the privacy budget according to the changing pattern of local truths. Besides, a reliability-based perturbation mechanism is proposed to reduce the perturbation magnitude based on worker's reliability. We theoretical analyze the data utility and computation cost of PrivSTD, and prove that PrivSTD can satisfy w-event (,)-differential privacy. Extensive experimental results on synthetic and real-world datasets demonstrate that PrivSTD achieves better utility than the state-of-the-art approaches.

Network storage services have benefited countless users worldwide due to the notable features of convenience, economy and high availability. Since a single service provider is not always reliable enough, more complex multi-cloud storage systems are developed for mitigating the data corruption risk. While a data auditing scheme is still needed in multi-cloud storage to help users confirm the integrity of their outsourced data. Unfortunately, most of the corresponding schemes rely on trusted institutions such as the centralized third-party auditor (TPA) and the cloud service organizer, and it is difficult to identify malicious service providers after service disputes. Therefore, we present a blockchain-based multi-cloud storage data auditing scheme to protect data integrity and accurately arbitrate service disputes. We not only introduce the blockchain to record the interactions among users, service providers, and organizers in data auditing process as evidence, but also employ the smart contract to detect service dispute, so as to enforce the untrusted organizer to honestly identify malicious service providers. We also use the blockchain network and homomorphic verifiable tags to achieve the low-cost batch verification without TPA. Theoretical analyses and experiments reveal that the scheme is effective in multi-cloud environments and the cost is acceptable.

In the autonomous driving era, high-definition (HD) maps is an essential building block to enable fine-grained environmental perception, precise localization, and path planning. However, with rich multi-dimensional information, the size of HD map data is huge and cannot be stored on-board, where the dynamic map data needs to be distributed in real-time via vehicular networks and how to design the distribution mechanism (i.e., determining the data source for requests) becomes crucial. For the end-to-end communication protocols (i.e., TCP/IP), the main limitation is the vehicle mobility and high dynamic of the network topology, which can degrade the transmission performance dramatically. Therefore, in this paper, we propose a Reinforcement Learning-based data Source Selection scheme, named RLSS, for efficient HD map distribution in vehicular named data networking (NDN) scenarios, which aims at seeking the best data source (roadside infrastructures or nearby vehicles) in accordance with the map data requests. Specifically, in RLSS, we adopt a deep reinforcement learning-based architecture to learn a neural network as an agent to make the decision of data source selection, which can work online after offline training based on historical selection action performance. In addition, to solve the “cold start” problem for a new vehicle, we propose a model aggregation algorithm and weight update approach to learn the model parameters from its nearby vehicles, which can guarantee the performance while saving the communication cost. Finally, we implement RLSS in NS-3 by adopting the tools of the ndnSIM, SUMO, and Gym. Extensive simulations demonstrate that RLSS can significantly improve the transmission performance in terms of delay, throughput, and packet loss when compared with state-of-the-art data source selection schemes.

In this paper, we study Space-Air-Ground integrated Vehicular Network (SAGVN), and propose an online control framework to dynamically slice the SAG spectrum resource for isolated vehicular services provisioning. In particular, at a given time slot, the system makes online decisions on the request admission and scheduling, UAV dispatching, and resource slicing for different services. To characterize the impact of those parameters, we construct a time-averaged queue stability criteria by taking queue backlogs of all services into consideration, and formulate a system revenue function which incorporates the time-averaged system throughput and UAV dispatching cost. The objective is to maximize the system revenue while stabilizing the time-averaged queue, which falls into the scope of Lyapunov optimization theory. By bounding the drift-plus-penalty, the original problem can be decoupled into four independent subproblems, each of which is readily solved. The merits of our control framework are three-fold: 1) the system is able to admit and process as many requests as possible (i.e., maximizing the time-averaged throughput); 2) the time-averaged UAV dispatching cost is minimized; and 3) service queues are stabilized in the long-term. Extensive simulations are carried out, and the results demonstrate that the control framework can effectively achieve the system revenue maximization and queueing stabilization. Moreover, it can balance the trade-off among system throughput, UAV dispatching cost, and queueing states via parameter tuning. Compared with the fixed slicing, our dynamic slicing can react to the vehicular environment rapidly and achieve an average 26% of throughput improvement.

Device-to-device (D2D) content sharing holds great promise to alleviate the growing strain on cellular networks, as it offloads popular content data onto direct peer-to-peer links. However, it is still unexplored how content sharing could benefit from utilizing multihop rather than the conventional single-hop D2D communications. As a step towards this end, this paper proposes a game theoretic approach to enable D2D content sharing with multihop communication capabilities. Given a subset of participants, a Nash bargaining game is modeled to provide the routing and pricing graphs, where a novel incentive mechanism is adopted to stimulate cooperation. By iteratively evaluating the solution of the Nash bargaining subgame, participants that include content sources and transmission relays are determined, which ensures that all participants make contributions to the content sharing process. An additional procedure termed pricing plan is introduced to make sure that the final pricing graph is practical and feasible in terms of D2D communication. Experimental results are presented to demonstrate that the proposed game theoretic approach could not only jointly deal with the participants selection, routing, and pricing problems in multihop D2D content sharing, but also effectively restrict utilities and transmission resources to only contributive participants.

Edge computing combing with artificial intelligence (AI) has enabled the timely processing and analysis of streaming data produced by IoT intelligent applications. However, it causes privacy risk due to the data exchanges between local devices and untrusted edge servers. The powerful analytical capability of AI further exacerbates the risks because it can even infer private information from insensitive data. In this paper, we propose a privacy-preserving IoT streaming data analytical framework based on edge computing, called PrivStream, to prevent the untrusted edge server from making sensitive inferences from the IoT streaming data. It utilizes a well-designed deep learning model to filter the sensitive information and combines with differential privacy to protect against the untrusted edge server. The noise is also injected into the framework in the training phase to increase the robustness of PrivStream to differential privacy noise. Taking into account the dynamic and real-time characteristics of streaming data, we realize PrivStream with two types of models to process data segment with fixed length and variable length, respectively, and implement it on a distributed streaming platform to achieve real-time streaming data transmission. We theoretically prove that Privstream satisfies e -differential privacy and experimentally demonstrate that PrivStream has better performance than the state-of-the-art and has acceptable computation and storage overheads.

Both voice communication and automatic speech verification (ASV) over smart devices are vulnerable to voice impersonation (VI) attack, which is often launched via imitating a target’s voice characteristics to deceive human auditory sense or fool the ASV system. Researchers have designed a number of defense schemes yet without consideration of universality due to the lack of comprehensive datasets. In this paper, we propose a universal defense scheme based on the VI dataset collected from a famous TV show named “The Sound”. First, we deliver a thorough study on the VI attacks in both auditory and ASV systems to verify the collected simulated voice could spoof the auditory and the ASV system with a notable probability. Second, we propose a quasi-gaussian distribution (QGD) based defense scheme with the discovery about specific voice characteristics are distinct between attackers and targets. Finally, we conduct extensive experimental results on our collected VI dataset as well as the auxiliary ASVspoof2017 dataset, to indicate the proposed QGD scheme outperforms the state-of-the-art schemes: Back-Propagation Neural Network, Support Vector Machine and Gaussian Mixture Model, in terms of accuracy.

While tremendous growing mobile apps offer users rich services and functionalities, they also bring significant performance and energy issues. Code sharing is promising to address these issues, but existing application-level code sharing is rather restrictive. This paper develops the a transparent machine code sharing for mobile devices, and presents its design, implementation, and deployment. SnapCode enables machine code sharing across a wide variety of commercial off-the-shelf Android devices. By sharing and running machine code, SnapCode can offer significant speed-ups: an average speed-up of 9.9X for one-time trial apps, and up to 120X in apps, regular uses. In addition, it can save more than 80% energy consumption.

The accurate segmentation of medical images is crucial to medical care and research; however, many efficient supervised image segmentation methods require sufficient pixel level labels. Such requirement is difficult to meet in practice and even impossible in some cases, e.g., rare Pathoma images. Inspired by traditional unsupervised methods, we propose a novel Chan-Vese model based on the Markov chain for unsupervised medical image segmentation. It combines local information brought by superpixels with the global difference between the target tissue and the background. Based on the Chan-Vese model, we utilize weight maps generated by the Markov chain to model and solve the segmentation problem iteratively using the min-cut algorithm at the superpixel level. Our method exploits abundant boundary and local region information in segmentation and thus can handle images with intensity inhomogeneity and object sparsity. In our method, users gain the power of fine-tuning parameters to achieve satisfactory results for each segmentation. By contrast, the result from deep learning based methods is rigid. The performance of our method is assessed by using four Computerized Tomography (CT) datasets. Experimental results show that the proposed method outperforms traditional unsupervised segmentation techniques.

Millimeter-wave (mmWave) frequency bands, which offer abundant underutilized spectral resources, have been explored and exploited in the past several years to meet the requirements of emerging wireless services highlighted by high data rates, ultrareliability, and ultralow delivery latency. Yet, the unique characteristics of mmWave, e.g., continuous wide bandwidth, large path, and penetration losses, along with hardware constraints, call for innovative technologies for mmWave communication. Recently, an extensive amount of work on mmWave communication has been carried out by researchers and practitioners from both academia and industry, and various technologies have been developed for mmWave communication systems to fulfill the full potential of mmWave frequency bands. In this article, we present a comprehensive survey of the standardization of mmWave communication, the latest progress and outcomes of the research on mmWave communication technologies, and the emerging applications of mmWave communication. In particular, we provide a timely and in-depth summary of the state-of-the-art technology specifications of mmWave communication with an emphasis on the physical (PHY) layer. Then, we elaborate on a number of well-established or promising antenna architectures in mmWave communication systems and investigate the enabling PHY layer transmission technologies. Finally, we show some existing and emerging applications of mmWave communication and discuss the potential open research issues.

Radio frequency (RF) sensors such as radar are instrumental for continuous, contactless sensing of vital signs, especially heart rate (HR) and respiration rate (RR). However, decades of related research mainly focused on static subjects, because the motion artifacts from other body parts may easily overwhelm the weak reflections from vital signs. This paper marks a first step in enabling RF vital sign sensing under ambulant daily living conditions. Our solution is inspired by existing physiological research that revealed the correlation between vital signs and body movement. Specifically, we propose to combine direct RF sensing for static instances and indirect vital sign prediction based on movement power estimation. We design customized machine learning models to capture the sophisticated correlation between RF signal pattern, movement power, and vital signs. We further design an instant calibration and adaptive training scheme to enable cross-subjects generalization, without any explicit data labeling from unknown subjects. We prototype and evaluate the framework using a commodity radar sensor. Under a variety of moving conditions, our solution demonstrates an average estimation error of 5.57 bpm for HR and 3.32 bpm for RR across multiple subjects, which largely outperforms state-of-the-art systems.

Widespread and large-scale WiFi systems have been deployed in many corporate locations, while the backhual capacity becomes the bottleneck in providing high-rate data services to a tremendous number of WiFi users. Mobile edge caching is a promising solution to relieve backhaul pressure and deliver quality services by proactively pushing contents to access points (APs). However, how to deploy cache in large-scale WiFi system is not well studied yet quite challenging since numerous APs can have heterogeneous traffic characteristics, and future traffic conditions are unknown ahead. In this paper, given the cache storage budget, we explore the cache deployment in a large-scale WiFi system, which contains 8,000 APs and serves more than 40,000 active users, to maximize the long-term caching gain. Specifically, we first collect two-month user association records and conduct intensive spatio-temporal analytics on WiFi traffic consumption, gaining two major observations. First, per AP traffic consumption varies in a rather wide range and the proportion of AP distributes evenly within the range, indicating that the cache size should be heterogeneously allocated in accordance to the underlying traffic demands. Second, compared to a single AP, the traffic consumption of a group of APs (clustered by physical locations) is more stable, which means that the short-term traffic statistics can be used to infer the future long-term traffic conditions. We then propose our cache deployment strategy, named LeaD (i.e., L arge-scale WiFi E dge c A che D eployment), in which we first cluster large-scale APs into well-sized edge nodes, then conduct the stationary testing on edge level traffic consumption and sample sufficient traffic statistics in order to precisely characterize long-term traffic conditions, and finally devise the TEG ( T raffic-w E ighted G reedy) algorithm to solve the long-term caching gain maximization problem. Extensive trace-driven experiments are carried out, and the results demonstrate that LeaD is able to achieve the near-optimal caching performance and can outperform other benchmark strategies significantly.

With the proliferation of smartphones, recent years have witnessed the rapid development of smartphone-based indoor navigation systems. However, existing solutions either bear high deployment cost or cannot support large-scale navigation. A scalable and plug-and-play indoor navigation system is still highly desirable. In this paper, we propose DeepNav, a new indoor navigation system that fully uses visual CNN to realize large-scale navigation. DeepNav adopts a single-pilot deployment scheme to realize fast deployment. It divides the indoor area into dense sub-areas to simplify image-based location matching while ensuring reasonable resolution. Practical realization of DeepNav entails a set of key challenges, e.g., invalid image recognition, classification of thousands of labels and under-fitting. In order to solve these challenges, we propose invalid image filter, subgroup sigmoid layer and movable object filter, respectively, for DeepNav. Finally, we implement a prototype of DeepNav on commercial smartphones. Experimental results demonstrate that DeepNav can be quickly deployed (e.g., within an hour in a 4-storey building) with an average localization error of 2.3 meters.

IMU based inertial tracking plays an indispensable role in many mobility centric tasks, such as robotic control, indoor navigation and virtual reality gaming. Despite its mature application in rigid machine mobility (e.g., robot and aircraft), tracking human users via mobile devices remains a fundamental challenge due to the intractable gait/posture patterns. Recent data-driven models have tackled sensor drifting, one key issue that plagues inertial tracking. However, these systems still assume the devices are held or attached to the user body with a relatively fixed posture. In practice, natural body activities may rotate/translate the device which may be mistaken as whole body movement. Such motion artifacts remain as the dominating factor that fails existing inertial tracing systems in practical uncontrolled settings. Inspired by the observation that human heads induces far less intensive movement relative to the body during walking, compared to other parts, we propose a novel multi-stage sensor fusion pipeline called DeepIT, which realizes inertial tracking by synthesizing the IMU measurements from a smartphone and an associated earbud. DeepIT introduces a data-driven reliability aware attention model, which assesses the reliability of each IMU and opportunistically synthesizes their data to mitigate the impacts of motion noise. Furthermore, DeepIT uses a reliability aware magnetometer compensation scheme to combat the angular drifting problem caused by unrestricted motion artifacts. We validate DeepIT on the first large-scale inertial navigation dataset involving both smartphone and earbud IMUs. The evaluation results show that DeepIT achieves multiple folds of accuracy improvement on the challenging uncontrolled natural walking scenarios, compared with state-of-the-art closed-form and data-driven models.

Industrial data plays a key role in the industrial internet, and its secure collection problem has been highly valued by researchers. As Industrial Internet of Things (IIoT) devices are geographically dispersed and difficult to link, blockchain technology is usually introduced to solve the security management problem of industrial data. Unfortunately, the IIoT device is not stable, and it may leave incorrect messages in the blockchain, which will be permanently stored with potentially catastrophic consequences. As an effective solution, the redactable blockchain technology can allow people to modify the data on the blockchain. However, the existing redactable blockchain cannot guarantee industrial data security in the industrial internet due to requirements of trusted third parties, large overheads or lack of accountability mechanism. In this paper, we propose a trustworthy industrial data management scheme based on redactable blockchain in the industrial internet. To avoid additional burdens on industrial blockchain systems, a double-blockchain architecture is established to separate trapdoor management transactions. Distributed chameleon hash parameter generation and trapdoor recovery methods can avoid the security problems faced by the centralized organization. The fault-tolerant trapdoor recovery mechanism based on verifiable secret sharing technology as an alternative enhances the security of the system. The blockchain will record various information in the trapdoor management process and use it as evidence for accountability when disputes arise. The theoretical analysis and experiments show that the approach can effectively deal with malicious behaviors and has acceptable overhead.

The articles in this special section focus on vehicular networks in the era of 6G mobile communication. With the growth of the vehicle population, vehicular networks play a key role in building safe, efficient, and intelligent transport systems and has been attracting a lot of attention from both academic and industrial communities around the world. The rise of autonomous driving technology and the prosperity of mobile applications, e.g., real-time video analytic, image-aided navigation, natural language processing, and etc, have brought tremendous pressure on current vehicular networks, e.g., high bandwidth, ultra-low latency, high reliability, high security, powerful computation capability, and massive connections. It is necessary to continue to develop vehicular networks by combining the latest research intends in other fields to meet quickly rising communication and computation demands. The upcoming 6G technology, which provides Holographic and Artificial Intelligence (AI) enabled communications, together with the increasing implementation of artificial intelligence in mobile devices, will lead to a new research trend to end-edge-cloud orchestrated computing with intelligence. It means that, not only the intelligent communication protocols, but also the intelligent computing resource management and machine learning algorithms among the mobile vehicles, the edge and the cloud, should be redesigned to support the development of vehicular networks.

The emergence of 5 G technology contributes to create more open and efficient eco-systems for various vertical industries. Especially, it significantly improves the capabilities of the vertical industries focusing on content-sharing services like mobile telemedicine, etc. However, cyber threats such as information leakage or piracy are more likely to occur in an open 5 G networks. So tracking information leakage in 5 G environments has become a daunting task. The existing tracing and accountability schemes have nonnegligible limitations in practice due to the dependence on a Trusted Third Party (TTP) or being encumbered with the significant overhead. Fortunately, the blockchain helps to mitigate these problems. In this paper, we propose a blockchain-enabled accountability mechanism against information leakage in the content-sharing services of the vertical industry services. For any information converted to vector form, we use the blockchain technology to ensure that service providers and clients can securely and fairly generate and share watermarked content. Besides, the homomorphic encryption is introduced to avoid the disclosure of the watermarking content, which guarantees the subsequent TTP-free arbitration. Finally, we theoretically analyze the security of the scheme and verify its performance.