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    SPECIAL FOCUS
  • SPECIAL FOCUS
    Lihui Wang, Dongya Shen, Qiuhua Lin, Zhiyong Luo, Wenjian Wang, Jianpei Chen, Zhao Gao, Wei Zhang
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    In this paper, an integrated substrate gap waveguide (ISGW) filtering antenna is proposed at millimeter wave band, whose surface wave and spurious modes are simultaneously suppressed. A second-order filtering response is obtained through a coupling feeding scheme using one uniform impedance resonator (UIR) and two stepped-impedance resonators (SIRs). To increase the stopband width of the antenna, the spurious modes are suppressed by selecting the appropriate sizes of the ISGW unit cell. Furthermore, the ISGW is implemented to improve the radiation performance of the antenna by alleviating the propagation of surface wave. And an equivalent circuit is investigated to reveal the working principle of ISGW. To demonstrate this methodology, an ISGW filtering antenna operating at a center frequency of 25 GHz is designed, fabricated, and measured. The results show that the antenna achieves a stopband width of 1.6$f_0$ (center frequency), an out-of-band suppression level of 21 dB, and a peak realized gain of 8.5 dBi.

  • COVER PAPER
  • COVER PAPER
    Xiang Cheng, Ziwei Huang, Lu Bai, Haotian Zhang, Mingran Sun, Boxun Liu, Sijiang Li, Jianan Zhang, Minson Lee
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    The sixth generation (6G) of mobile communication system is witnessing a new paradigm shift, i.e., integrated sensing-communication system. A comprehensive dataset is a prerequisite for 6G integrated sensing-communication research. This paper develops a novel simulation dataset, named M3SC, for mixed multi-modal (MMM) sensing-communication integration, and the generation framework of the M3SC dataset is further given. To obtain multi-modal sensory data in physical space and communication data in electromagnetic space, we utilize AirSim and WaveFarer to collect multi-modal sensory data and exploit Wireless InSite to collect communication data. Furthermore, the in-depth integration and precise alignment of AirSim, WaveFarer, and Wireless InSite are achieved. The M3SC dataset covers various weather conditions, multiplex frequency bands, and different times of the day. Currently, the M3SC dataset contains 1500 snapshots, including 80 RGB images, 160 depth maps, 80 LiDAR point clouds, 256 sets of mmWave waveforms with 8 radar point clouds, and 72 channel impulse response (CIR) matrices per snapshot, thus totaling 120,000 RGB images, 240,000 depth maps, 120,000 LiDAR point clouds, 384,000 sets of mmWave waveforms with 12,000 radar point clouds, and 108,000 CIR matrices. The data processing result presents the multi-modal sensory information and communication channel statistical properties. Finally, the MMM sensing-communication application, which can be supported by the M3SC dataset, is discussed.

  • REVIEW PAPER
  • REVIEW PAPER
    Yanli Xu, Jian Shang, Hao Tang
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    With the vigorous development of automobile industry, in-vehicle network is also constantly upgraded to meet data transmission requirements of emerging applications. The main transmission requirements are low latency and certainty especially for autonomous driving. Time sensitive networking (TSN) based on Ethernet gives a possible solution to these requirements. Previous surveys usually investigated TSN from a general perspective, which referred to TSN of various application fields. In this paper, we focus on the application of TSN to the in-vehicle networks. For in-vehicle networks, we discuss all related TSN standards specified by IEEE 802.1 work group up to now. We further overview and analyze recent literature on various aspects of TSN for automotive applications, including synchronization, resource reservation, scheduling, certainty, software and hardware. Application scenarios of TSN for in-vehicle networks are analyzed one by one. Since TSN of in-vehicle network is still at a very initial stage, this paper also gives insights on open issues, future research directions and possible solutions.

  • COMMUNICATIONS THEORIES & SYSTEMS
  • COMMUNICATIONS THEORIES & SYSTEMS
    Weimin Wang, Hongmin Zhao, Yongle Wu, Xiaopan Chen
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    In this paper, a 5G wideband power amplifier (PA) with bandpass filtering response is synthesized using a bandwidth-extended bandpass filter as the matching network (MN). In this structure, the bandwidth ($\theta_{\mathrm{C}}$) is defined as a variable in the closed-form equations provided by the microstrip bandpass filter. It can be extended over a wide range only by changing the characteristic impedances of the structure. Different from the other wideband MNs, the extension of bandwidth does not increase the complexity of the structure (order n is fixed). In addition, based on the bandwidth-extended structure, the wideband design of bandpass filtering PA is not limited to the fixed bandwidth of the specific filter structure. The theoretical analysis of the MN and the design flow of the PA are provided in this design. The fabricated bandpass filtering PA can support almost one-octave bandwidth (2-3.8 GHz), covering the two 5G bands (n41 and n78). The drain efficiency of 47%-60% and output power higher than 40 dBm are measured. Good frequency selectivity in S-parameter measurements can be observed.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Shuchao Mi, Jianyong Zhang, Fengju Fan, Baorui Yan, Muguang Wang
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    This paper proposes the alternating direction method of multipliers-based infinity-norm (ADMIN) with threshold (ADMIN-T) and with percentage (ADMIN-P) detection algorithms, which make full use of the distribution of the signal to interference plus noise ratio (SINR) for an uplink massive MIMO system. The ADMIN-T and ADMIN-P detection algorithms are improved visions of the ADMIN detection algorithm, in which an appropriate SINR threshold in the ADMIN-T detection algorithm and a certain percentage in the ADMIN-P detection algorithm are designed to reduce the overall computational complexity. The detected symbols are divided into two parts by the SINR threshold which is based on the cumulative probability density function (CDF) of SINR and a percentage, respectively. The symbols in higher SINR part are detected by MMSE. The interference of these symbols is then cancelled by successive interference cancellation (SIC). Afterwards the remaining symbols with low SINR are iteratively detected by ADMIN. The simulation results show that the ADMIIN-T and the ADMIN-P detection algorithms provide a significant performance gain compared with some recently proposed detection algorithms. In addition, the computational complexity of ADMIN-T and ADMIN-P are significantly reduced. Furthermore, in the case of same number of transceiver antennas, the proposed algorithms have a higher performance compared with the case of asymmetric transceiver antennas.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Jianhong Chu, Zhi Zhang, Yu Guo
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    Generally, due to the limitation of the dimension of the array aperture, linear arrays cannot achieve two-dimensional (2D) direction of arrival (DOA) estimation. But the emergence of array motion provides a chance for that. In this paper, a generalized motion scheme and a novel method of 2D DOA estimation are proposed by exploring the linear array motion. To be specific, the linear arrays are controlled to move along an arbitrary direction at a constant velocity and snap per fixed time delay. All the received signals are processed to synthesize the comprehensive observation vector for an extended 2D virtual aperture. Subsequently, since most of 2D DOA estimation methods are not universal to our proposed motion scheme and the reduced-dimensional (RD) method fails to handle the case of the coupled parameters, a decoupled reduced-complexity multiple signals classification (DRC MUSIC) algorithm is designed specifically. Simulation results demonstrate that: a) our proposed scheme can achieve underdetermined 2D DOA estimation just by the linear arrays; b) our designed DRC MUSIC algorithm has the good properties of high accuracy and low complexity; c) our proposed motion scheme with the DRC method has better universality in the motion direction.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Qingyan Ren, Yanjing Sun, Song Li, Bin Wang, Zhengda Yu
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    Underwater magnetic induction (MI)-assisted acoustic cooperative multiple-input-multiple-output (MIMO) has been recently proposed as a promising technique for underwater wireless sensor networks (UWSNs). For the more, the energy utilization of energy-constrained sensor nodes is one of the key issues in UWSNs, and it relates to the network lifetime. In this paper, we present an energy-efficient data collection for underwater MI-assisted acoustic cooperative MIMO wireless sensor networks (WSNs), including the formation of cooperative MIMO and relay link establishment. Firstly, the cooperative MIMO is formed by considering its expected transmission range and the energy balance of nodes with it. Particularly, from the perspective of the node's energy consumption, the expected cooperative MIMO size and the selection of master node (MN) are proposed. Sequentially, to improve the coverage of the networks and prolong the network lifetime, relay links are established by relay selection algorithm that using matching theory. Finally, the simulation results show that the proposed data collection improves its efficiency, reduces the energy consumption of the master node, improves the networks' coverage, and extends the network lifetime.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Maozhe Xu, Guanjun Xu, Youran Dong, Weizhi Wang, Qinyu Zhang, Zhaohui Song
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    Free space optical (FSO) communication has recently aroused great interest in academia due to its unique features, such as large transmission band, high data rates, and strong anti-electromagnetic interference. With the aim of evaluating the performance of an FSO communication system and extending the line-of-sight transmission distance, we propose an unmanned aerial vehicle (UAV)-assisted dual-hop FSO communication system equipped with amplify-and-forward protocol at the relay node. Specifically, we consider impairments of atmospheric absorption, pointing errors, atmospheric turbulence, and link interruptions due to angle-of-arrival fluctuations in the relay system. The Gamma-Gamma and Málaga distributions are used to model the influence of atmospheric turbulence on the source-to-UAV and UAV-to-destination links, respectively. We derive closed-form expressions of the probability density function (PDF) and cumulative distribution function (CDF) for the proposed communication system, in terms of the Meijer-G function. Based on the precise PDF and CDF, analytical expressions for the outage probability, average bit error rate, and ergodic capacity are proposed with the aid of the extended generalized bivariate Fox’s H function. Finally, we show that there is a match between the analytical results and numerical results, and we analyze the influence of the system and channel parameters on the performance.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Ran Liu, Daniel N. Aloi
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    Vehicle-to-Everything (V2X) communications will be an essential part of the technology in future autonomous drive decision systems. A fundamental procedure is to establish a robust communication channel between end-to-end devices. Due to the antenna placed at different positions on vehicles, the existing cellular electro-magnetic (EM) wave propagation modelling does not fit properly for V2X direct communication application. In order to figure out a feasible understanding of this problem, this paper focuses on the propagation channel analysis in a rural Vehicle-to-Vehicle (V2V) scenario for vehicular communication with antenna position experiments at different heights. By adopting the ray-tracing algorithm, a rural scenario simulation model is built up via the use of a commercial-off-the-shelf (COTS) EM modelling software package, that computes the path loss received power and delay spread for a given propagation channel. Next, a real-world vehicle measurement campaign was performed to verify the simulation results. The simulated and measured receiver power was in good agreement with each other, and the results of this study considered two antenna types located at three different relative heights between the two vehicles. This research provides constructive guidance for the V2V antenna characteristics, antenna placement and vehicle communication channel analysis.
  • NETWORKS & COMPUTING
  • NETWORKS & COMPUTING
    Chundong Xu, Cheng Zhu, Xianpeng Ling, Dongwen Ying
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    In the field of speech bandwidth extension, it is difficult to achieve high speech quality based on the shallow statistical model method. Although the application of deep learning has greatly improved the extended speech quality, the high model complexity makes it infeasible to run on the client. In order to tackle these issues, this paper proposes an end-to-end speech bandwidth extension method based on a temporal convolutional neural network, which greatly reduces the complexity of the model. In addition, a new time-frequency loss function is designed to enable narrowband speech to acquire a more accurate wideband mapping in the time domain and the frequency domain. The experimental results show that the reconstructed wideband speech generated by the proposed method is superior to the traditional heuristic rule based approaches and the conventional neural network methods for both subjective and objective evaluation.
  • NETWORKS & COMPUTING
    Yongan Guo, Yuao Wang, Qijie Qian
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    The demand for the Internet of Everything has slowed down network routing efficiency. Traditional routing policies rely on manual configuration, which has limitations and adversely affects network performance. In this paper, we propose an Internet of Things (IoT) Intelligent Edge Network Routing (ENIR) architecture. ENIR uses deep reinforcement learning (DRL) to simulate human learning of empirical knowledge and an intelligent routing closed-loop control mechanism for real-time interaction with the network environment. According to the network demand and environmental conditions, the method can dynamically adjust network resources and perform intelligent routing optimization. It uses blockchain technology to share network knowledge and global optimization of network routing. The intelligent routing method uses the deep deterministic policy gradient (DDPG) algorithm. Our simulation results show that ENIR provides significantly better link utilization and transmission delay performance than various routing methods (e.g., open shortest path first, routing based on Q-learning and DRL-based control framework for traffic engineering).
  • NETWORKS & COMPUTING
    Ying Chen, Wei Gu, Jiajie Xu, Yongchao Zhang, Geyong Min
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    Limited by battery and computing resources, the computing-intensive tasks generated by Internet of Things (IoT) devices cannot be processed all by themselves. Mobile edge computing (MEC) is a suitable solution for this problem, and the generated tasks can be offloaded from IoT devices to MEC. In this paper, we study the problem of dynamic task offloading for digital twin-empowered MEC. Digital twin techniques are applied to provide information of environment and share the training data of agent deployed on IoT devices. We formulate the task offloading problem with the goal of maximizing the energy efficiency and the workload balance among the ESs. Then, we reformulate the problem as an MDP problem and design DRL-based energy efficient task offloading (DEETO) algorithm to solve it. Comparative experiments are carried out which show the superiority of our DEETO algorithm in improving energy efficiency and balancing the workload.
  • NETWORKS & COMPUTING
    Yongkai Fan, Wanyu Zhang, Jianrong Bai, Xia Lei1, Kuanching Li
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    In the analysis of big data, deep learning is a crucial technique. Big data analysis tasks are typically carried out on the cloud since it offers strong computer capabilities and storage areas. Nevertheless, there is a contradiction between the open nature of the cloud and the demand that data owners maintain their privacy. To use cloud resources for privacy-preserving data training, a viable method must be found. A privacy-preserving deep learning model (PPDLM) is suggested in this research to address this preserving issue. To preserve data privacy, we first encrypted the data using homomorphic encryption (HE) approach. Moreover, the deep learning algorithm's activation function—the sigmoid function—uses the least-squares method to process non-addition and non-multiplication operations that are not allowed by homomorphic. Finally, experimental results show that PPDLM has a significant effect on the protection of data privacy information. Compared with Non-Privacy Preserving Deep Learning Model (NPPDLM), PPDLM has higher computational efficiency.
  • NETWORKS & COMPUTING
    Yuchen Zhou, Jian Chen, Lu Lyu, Bingtao He
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    To promote the application of edge computing in wireless blockchain networks, this paper presents a business ecosystem, where edge computing is introduced to assist blockchain users in implementing the mining process. This paper exploits resource trading and miner competition to enable secure and efficient transactions in the presented business ecosystem. The resource trading problem is formulated as a Stackelberg game between miner candidates and edge computing servers, where computing, caching, and communication resources are jointly optimized to maximize the potential profit. Partial offloading is introduced to further enhance the system performance when compared with the existing work. We analyze the existence and uniqueness of the Nash equilibrium and Stackelberg equilibrium. Based on the optimization result, winners are selected from the set of miner candidates by bidding and constitute the mining network. Simulation results demonstrate that the proposal is able to improve the social welfare of blockchain miners, thus stimulating more blockchain users to join the mining network.
  • SECURITY
  • SECURITY
    Xiuzhang Yang, Guojun Peng, Dongni Zhang, Yuhang Gao, Chenguang Li
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    PowerShell has been widely deployed in fileless malware and advanced persistent threat (APT) attacks due to its high stealthiness and live-off-the-land technique. However, existing works mainly focus on deobfuscation and malicious detection, lacking the malicious PowerShell families classification and behavior analysis. Moreover, the state-of-the-art methods fail to capture fine-grained features and semantic relationships, resulting in low robustness and accuracy. To this end, we propose PowerDetector, a novel malicious PowerShell script detector based on multi-modal semantic fusion and deep learning. Specifically, we design four feature extraction methods to extract key features from character, token, abstract syntax tree (AST), and semantic knowledge graph. Then, we intelligently design four embeddings (i.e., Char2Vec, Token2Vec, AST2Vec, and Rela2Vec) and construct a multi-modal fusion algorithm to concatenate feature vectors from different views. Finally, we propose a combined model based on transformer and CNN-BiLSTM to implement PowerShell family detection. Our experiments with five types of PowerShell attacks show that PowerDetector can accurately detect various obfuscated and stealth PowerShell scripts, with a 0.9402 precision, a 0.9358 recall, and a 0.9374 $F_1$-score. Furthermore, through single-modal and multi-modal comparison experiments, we demonstrate that PowerDetector's multi-modal embedding and deep learning model can achieve better accuracy and even identify more unknown attacks.
  • SECURITY
    Xiao Liu, Mingyuan Li, Haipeng Peng, Shoushan Luo
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    With the rapid development of the Internet of Things (IoT), there is an increasing need for interaction between different networks. In order to improve the level of interconnection, especially the interoperability of users/devices between different nodes is very important. In the IoT heterogeneous blockchain scenario, how to ensure the legitimacy of the chain and how to confirm the identity of cross-chain information users/devices become the key issues to be solved for blockchain interoperability. In this paper, we propose a secure and trusted interoperability mechanism for IoT based on heterogeneous chains to improve the security of blockchain interoperability. In this mechanism, a primary sidechain architecture supporting authentication at both ends of the heterogeneous chain is designed. In addition, a distributed gateway architecture is proposed for cross-chain authentication and protocol conversion. The security and performance analysis shows that our scheme is feasible and effective in improving the security of cross-chain operations in IoT.