January 2024 Vol. 21 No. 1  
  
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    6G NEW MULTIPLE ACCESS TECHNOLOGY
  • 6G NEW MULTIPLE ACCESS TECHNOLOGY
    Chunlin Yan, Siying Lyu, Sen Wang, Yuhong Huang, Xiaodong Xu
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    In this paper, ambient IoT is used as a typical use case of massive connections for the sixth generation (6G) mobile communications where we derive the performance requirements to facilitate the evaluation of technical solutions. A rather complete design of unsourced multiple access is proposed in which two key parts: a compressed sensing module for active user detection, and a sparse interleaver-division multiple access (SIDMA) module are simulated side by side on a same platform at balanced signal to noise ratio (SNR) operating points. With a proper combination of compressed sensing matrix, a convolutional encoder, receiver algorithms, the simulated performance results appear superior to the state-of-the-art benchmark, yet with relatively less complicated processing.

  • 6G NEW MULTIPLE ACCESS TECHNOLOGY
    Jiaqi Fang, Gangle Sun, Wenjin Wang, Li You, Rui Ding
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    This paper investigates the low earth orbit (LEO) satellite-enabled coded compressed sensing (CCS) unsourced random access (URA) in orthogonal frequency division multiple access (OFDMA) framework, where a massive uniform planar array (UPA) is equipped on the satellite. In LEO satellite communications, unavoidable timing and frequency offsets cause phase shifts in the transmitted signals, substantially diminishing the decoding performance of current terrestrial CCS URA receiver. To cope with this issue, we expand the inner codebook with predefined timing and frequency offsets and formulate the inner decoding as a tractable compressed sensing (CS) problem. Additionally, we leverage the inherent sparsity of the UPA-equipped LEO satellite angular domain channels, thereby enabling the outer decoder to support more active devices. Furthermore, the outputs of the outer decoder are used to reduce the search space of the inner decoder, which cuts down the computational complexity and accelerates the convergence of the inner decoding. Simulation results verify the effectiveness of the proposed scheme.

  • 6G NEW MULTIPLE ACCESS TECHNOLOGY
    Shiyu Liang, Wei Chen, Zhongwen Sun, Ao Chen, Bo Ai
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    Massive machine type communication aims to support the connection of massive devices, which is still an important scenario in 6G. In this paper, a novel cluster-based massive access method is proposed for massive multiple input multiple output systems. By exploiting the angular domain characteristics, devices are separated into multiple clusters with a learned cluster-specific dictionary, which enhances the identification of active devices. For detected active devices whose data recovery fails, power domain nonorthogonal multiple access with successive interference cancellation is employed to recover their data via re-transmission. Simulation results show that the proposed scheme and algorithm achieve improved performance on active user detection and data recovery.

  • 6G NEW MULTIPLE ACCESS TECHNOLOGY
    Wei Zhang, Xiaofeng Zhong, Shidong Zhou
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    This paper considers the frame-asynchronous grant-free rateless multiple access (FA-GF-RMA) scenario, where users can initiate access at any symbol time, using shared channel resources to transmit data to the base station. Rateless coding is introduced to enhance the reliability of the system. Previous literature has shown that FA-GF-RMA can achieve lower access delay than frame-synchronous grant-free rateless multiple access (FS-GF-RMA), with extreme reliability enabled by rateless coding. To support FA-GF-RMA in more practical scenarios, a joint activity and data detection (JADD) scheme is proposed. Exploiting the feature of sporadic traf?c, approximate message passing (AMP) is exploited for transmission signal matrix estimation. Then, to determine the packet start points, a maximum posterior probability (MAP) estimation problem is solved based on the recovered transmitted signals, leveraging the intrinsic power pattern in the codeword. An iterative power-pattern-aided AMP algorithm is devised to enhance the estimation performance of AMP. Simulation results verify that the proposed solution achieves a delay performance that is comparable to the performance limit of FA-GF-RMA.

  • 6G NEW MULTIPLE ACCESS TECHNOLOGY
    Ge Song, Xiaojie Fang, Xuejun Sha
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    The hybrid carrier (HC) system rooted in the carrier fusion concept is gradually garnering attention. In this paper, we study the extended hybrid carrier (EHC) multiple access scheme to ensure reliable wireless communication. By employing the EHC modulation, a power layered multiplexing framework is realized, which exhibits enhanced interference suppression capability owing to the more uniform energy distribution design. The implementation method and advantage mechanism are explicated respectively for the uplink and downlink, and the performance analysis under varying channel conditions is provided. In addition, considering the connectivity demand, we explore the non-orthogonal multiple access (NOMA) method of the EHC system and develop the EHC sparse code multiple access scheme. The proposed scheme melds the energy spread superiority of EHC with the access capacity of NOMA, facilitating superior support for massive connectivity in high mobility environments. Simulation results have verified the feasibility and advantages of the proposed scheme. Compared with existing HC multiple access schemes, the proposed scheme exhibits robust bit error rate performance and can better guarantee multiple access performance in complex scenarios of next-generation communications.

  • 6G NEW MULTIPLE ACCESS TECHNOLOGY
    Chaowu Wu, Yue Xiao, Shu Fang, Gang Wu
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    In this paper, we present a novel and robust nonlinear precoding (NLP) design and detection structure specifically tailored for multiple-input multiple-output space division multiple access (MIMO-SDMA) systems toward 6G wireless. Our approach aims to effectively mitigate the impact of imperfect channel estimation by leveraging the channel fluctuation mean square error (MSE) for reconstructing a highly accurate precoding matrix at the transmitter. Furthermore, we introduce a simplified receiver structure that eliminates the need for equalization, resulting in reduced interference and notable enhancements in overall system performance. We conduct both computer simulations and experimental tests to validate the efficacy of our proposed approach. The results reveals that the proposed NLP scheme offers significant performance improvements, making it particularly well-suited for the forthcoming 6G wireless.

  • COVER PAPER
  • COVER PAPER
    Shanzhi Chen, Xinxin He, Rui Zhao, Jinling Hu, Xin Zhang
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    Since the evolving standardization of cellular V2X (C-V2X) technologies is continuously developed by 3GPP, research on new radio (NR-V2X) has been on schedule by academic and industries. Though millimeter wave (mmWave) frequency band is supposed to provide large transmission bandwidth, yet the development of mmWave band in NR-V2X is still in preliminary stage. In this article, a comprehensive discussion of mmWave NR-V2X is given covering trends, standardization landscape, and enabling technologies, aiming at tackling the challenge of channel modeling, directional channel access, beamforming and blockage management. The vision of mmWave NR-V2X is to fully support the development of automated driving, holographic control display and improved in-car infotainment for the future.

  • REVIEW PAPER
  • REVIEW PAPER
    Yilin Zhou, Guojun Peng, Zichuan Li, Side Liu
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    According to the boot process of modern computer systems, whoever boots first will gain control first. Taking advantage of this feature, a malicious code called bootkit can hijack the control before the OS bootloader and bypass security mechanisms in boot process. That makes bootkits difficult to detect or clean up thoroughly. With the improvement of security mechanisms and the emergence of UEFI, the attack and defense techniques for bootkits have constantly been evolving. We first introduce two boot modes of modern computer systems and present an attack model of bootkits by some sophistical samples. Then we discuss some classic attack techniques used by bootkits from their initial appearance to the present on two axes, including boot mode axis and attack phase axis. Next, we evaluate the race to the bottom of the system and the evolution process between bootkits and security mechanisms. At last, we present the possible future direction for bootkits in the context of continuous improvement of OS and firmware security mechanisms.

  • COMMUNICATIONS THEORIES & SYSTEMS
  • COMMUNICATIONS THEORIES & SYSTEMS
    Shuo Liu, Pan Tang, Jianhua Zhang, Yue Yin, Yu Tong, Baobao Liu, Guangyi Liu, Liang Xia
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    Visible light communication (VLC) has attracted much attention in the research of sixth-generation (6G) systems. Furthermore, channel modeling is the foundation for designing efficient and robust VLC systems. In this paper, we present extensive VLC channel measurement campaigns in indoor environments, i.e., an office and a corridor. Based on the measured data, the large-scale fading characteristics and multipath-related characteristics, including omnidirectional optical path loss (OPL), K-factor, power angular spectrum (PAS), angle spread (AS), and clustering characteristics, are analyzed and modeled through a statistical method. Based on the extracted statistics of the above-mentioned channel characteristics, we propose a statistical spatial channel model (SSCM) capable of modeling multipath in the spatial domain. Furthermore, the simulated statistics of the proposed model are compared with the measured statistics. For instance, in the office, the simulated path loss exponent (PLE) and the measured PLE are 1.96 and 1.97, respectively. And, the simulated medians of AS and measured medians of AS are $25.94^\circ$ and $24.84^\circ$, respectively. Generally, the fact that the simulated results fit well with measured results has demonstrated the accuracy of our SSCM.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Yizhe Zhao, Yanliang Wu, Jie Hu, Kun Yang
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    Integrated data and energy transfer (IDET) enables the electromagnetic waves to transmit wireless energy at the same time of data delivery for low-power devices. In this paper, an energy harvesting modulation (EHM) assisted multi-user IDET system is studied, where all the received signals at the users are exploited for energy harvesting without the degradation of wireless data transfer (WDT) performance. The joint IDET performance is then analysed theoretically by conceiving a practical time-dependent wireless channel. With the aid of the AO based algorithm, the average effective data rate among users are maximized by ensuring the BER and the wireless energy transfer (WET) performance. Simulation results validate and evaluate the IDET performance of the EHM assisted system, which also demonstrates that the optimal number of user clusters and IDET time slots should be allocated, in order to improve the WET and WDT performance.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Mingyao Cui, Hao Jiang, Yuhao Chen, Yang Du, Linglong Dai
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    Channel prediction is critical to address the channel aging issue in mobile scenarios. Existing channel prediction techniques are mainly designed for discrete channel prediction, which can only predict the future channel in a fixed time slot per frame, while the other intra-frame channels are usually recovered by interpolation. However, these approaches suffer from a serious interpolation loss, especially for mobile millimeter-wave communications. To solve this challenging problem, we propose a tensor neural ordinary differential equation (TN-ODE) based continuous-time channel prediction scheme to realize the direct prediction of intra-frame channels. Specifically, inspired by the recently developed continuous mapping model named neural ODE in the field of machine learning, we first utilize the neural ODE model to predict future continuous-time channels. To improve the channel prediction accuracy and reduce computational complexity, we then propose the TN-ODE scheme to learn the structural characteristics of the high-dimensional channel by low-dimensional learnable transform. Simulation results show that the proposed scheme is able to achieve higher intra-frame channel prediction accuracy than existing schemes.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Yang Liu, Gang Li, Chengxiang Wang
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    In this paper, the channel impulse response matrix (CIRM) can be expressed as a sum of couplings between the steering vectors at the base station (BS) and the eigenbases at the mobile station (MS). Nakagami distribution was used to describe the fading of the coupling between the steering vectors and the eigenbases. Extensive measurements were carried out to evaluate the performance of this proposed model. Furthermore, the physical implications of this model were illustrated and the capacities are analyzed. In addition, the azimuthal power spectrum(APS) of several models was analyzed. Finally, the channel hardening effect was simulated and discussed. Results showed that the proposed model provides a better fit to the measured results than the other CBSM, i.e., Weichselberger model. Moreover, the proposed model can provide better tradeoff between accuracy and complexity in channel synthesis. This CIRM model can be used for massive MIMO design in the future communication system design.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Qiuhua Lin, Dongya Shen, Lihui Wang, Zhiyong Luo
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    A novel dual-band ISGW cavity filter with enhanced frequency selectivity is proposed in this paper by utilizing a multi-mode coupling topology. Its cavity is designed to control the number of modes, and then the ports are determined by analyzing the coupling relationship between these selected modes. By synthesizing the coupling matrix of the filter, a non-resonating node (NRN) structure is introduced to flexibly tune the frequency of modes, which gets a dual-band and quad-band filtering response from a tri-band filter no the NRN. Furthermore, a frequency selective surface (FSS) has been newly designed as the upper surface of the cavity, which significantly improves the bad out-of-band suppression and frequency selectivity that often exists in most traditional cavity filter designs and measurements. The results show that its two center frequencies are ${f_{01}}$ = 27.50 GHz and ${f_{02}}$ = 32.92 GHz, respectively. Compared with the dual-band filter that there is no the FSS metasurface, the out-of-band suppression level is improved from measured 5 dB to 18 dB, and its finite transmission zero (FTZ) numbers is increased from measured 1 to 4 between the two designed bands. Compared with the tri-band and quad-band filter, its passband bandwidth is expanded from measured 1.17 %, 1.14 %, and 1.13 % or 1.31 %, 1.50 %, 0.56 %, and 0.57 % to 1.71 % and 1.87 %. In addition, the filter has compact, small, and lightweight characteristics.
  • COMMUNICATIONS THEORIES & SYSTEMS
    Ke Wang, Baorui Feng, Jingui Zhao, Wenliang Lin, Zhongliang Deng, Dongdong Wang, Yi Cen2, Genan Wu
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    Low Earth Orbit (LEO) multibeam satellites will be widely used in the next generation of satellite communication systems, whose inter-beam interference will inevitably limit the performance of the whole system. Nonlinear precoding such as Tomlinson-Harashima precoding (THP) algorithm has been proved to be a promising technology to solve this problem, which has smaller noise amplification effect compared with linear precoding. However, the similarity of different user channels (defined as channel correlation) will degrade the performance of THP algorithm. In this paper, we qualitatively analyze the inter-beam interference in the whole process of LEO satellite over a specific coverage area, and the impact of channel correlation on Signal-to-Noise Ratio (SNR) of receivers when THP is applied. One user grouping algorithm is proposed based on the analysis of channel correlation, which could decrease the number of users with high channel correlation in each precoding group, thus improve the performance of THP. Furthermore, our algorithm is designed under the premise of co-frequency deployment and orthogonal frequency division multiplexing (OFDM), which leads to more users under severe inter-beam interference compared to the existing research on geostationary orbit satellites broadcasting systems. Simulation results show that the proposed user grouping algorithm possesses higher channel capacity and better bit error rate(BER) performance in high SNR conditions relative to existing works.
  • SIGNAL PROCESSING
  • SIGNAL PROCESSING
    Shengli Zhou, Cheng Xu, Rui Xu, Weijie Ding, Chao Chen, Xiaoyang Xu
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    The fraudulent website image is a vital information carrier for telecom fraud. The efficient and precise recognition of fraudulent website images is critical to combating and dealing with fraudulent websites. Current research on image recognition of fraudulent websites is mainly carried out at the level of image feature extraction and similarity study, which have such disadvantages as difficulty in obtaining image data, insufficient image analysis, and single identification types. This study develops a model based on the entropy method for image leader decision and Inception-v3 transfer learning to address these disadvantages. The data processing part of the model uses a breadth search crawler to capture the image data. Then, the information in the images is evaluated with the entropy method, image weights are assigned, and the image leader is selected. In model training and prediction, the transfer learning of the Inception-v3 model is introduced into image recognition of fraudulent websites. Using selected image leaders to train the model, multiple types of fraudulent websites are identified with high accuracy. The experiment proves that this model has a superior accuracy in recognizing images on fraudulent websites compared to other current models.
  • SIGNAL PROCESSING
    Jin Liu, Zan Li, Qiguang Miao, Li Yang
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    Weak signal reception is a very important and challenging problem for communication systems especially in the presence of non-Gaussian noise, and in which case the performance of optimal linear correlated receiver degrades dramatically. Aiming at this, a novel uncorrelated reception scheme based on adaptive bistable stochastic resonance (ABSR) for a weak signal in additive Laplacian noise is investigated. By analyzing the key issue that the quantitative cooperative resonance matching relationship between the characteristics of the noisy signal and the nonlinear bistable system, an analytical expression of the bistable system parameters is derived. On this basis, by means of bistable system parameters self-adaptive adjustment, the counterintuitive stochastic resonance (SR) phenomenon can be easily generated at which the random noise is changed into a benefit to assist signal transmission. Finally, it is demonstrated that approximately 8dB bit error ratio (BER) performance improvement for the ABSR-based uncorrelated receiver when compared with the traditional uncorrelated receiver at low signal to noise ratio (SNR) conditions varying from -30dB to -5dB.
  • NETWORKS & SECURITY
  • NETWORKS & SECURITY
    Hao Jiang, Hongming Zhang, Ting Liu
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    In this paper, a statistical cluster-based simulation channel model with a finite number of sinusoids is proposed for depicting the multiple-input multiple-output (MIMO) communications in vehicle-to-everything (V2X) environments. In the proposed sum-of-sinusoids (SoS) channel model, the waves that emerge from the transmitter undergo line-of-sight (LoS) and non-line-of-sight (NLoS) propagation to the receiver, which makes the model suitable for describing numerous V2X wireless communication scenarios for sixth-generation (6G). We derive expressions for the real and imaginary parts of the complex channel impulse response (CIR), which characterize the physical propagation characteristics of V2X wireless channels. The statistical properties of the real and imaginary parts of the complex CIRs, i.e., auto-correlation functions (ACFs), Doppler power spectral densities (PSDs), cross-correlation functions (CCFs), and variances of ACFs and CCFs, are derived and discussed. Simulation results are generated and match those predicted by the underlying theory, demonstrating the accuracy of our derivation and analysis. The proposed framework and underlying theory arise as an efficient tool to investigate the statistical properties of 6G MIMO V2X communication systems.
  • NETWORKS & SECURITY
    Yangang Wang, Xianglin Wei, Hai Wang, Yongyang Hu, Kuang Zhao, Jianhua Fan
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    Many efforts have been devoted to efficient task scheduling in Multi-Unmanned Aerial Vehicle (UAV) edge computing. However, the heterogeneity of UAV computation resource, and the task re-allocating between UAVs have not been fully considered yet. Moreover, most existing works neglect the fact that a task can only be executed on the UAV equipped with its desired service function (SF). In this backdrop, this paper formulates the task scheduling problem as a multi-objective task scheduling problem, which aims at maximizing the task execution success ratio while minimizing the average weighted sum of all tasks' completion time and energy consumption. Optimizing three coupled goals in a real-time manner with the dynamic arrival of tasks hinders us from adopting existing methods, like machine learning-based solutions that require a long training time and tremendous pre-knowledge about the task arrival process, or heuristic-based ones that usually incur a long decision-making time. To tackle this problem in a distributed manner, we establish a matching theory framework, in which three conflicting goals are treated as the preferences of tasks, SFs and UAVs. Then, a Distributed Matching Theory-based Re-allocating (DiMaToRe) algorithm is put forward. We formally proved that a stable matching can be achieved by our proposal. Extensive simulation results show that DiMaToRe algorithm outperforms benchmark algorithms under diverse parameter settings and has good robustness.
  • NETWORKS & SECURITY
    Junhui Zhao, Ziyang Zhang, Zhenghao Yi, Xiaoting Ma, Qingmiao Zhang
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    Edge computing paradigm for 5G architecture has been considered as one of the most effective ways to realize low latency and highly reliable communication, which brings computing tasks and network resources to the edge of network. The deployment of edge computing nodes is a key factor affecting the service performance of edge computing systems. In this paper, we propose a method for deploying edge computing nodes based on user location. Through the combination of Simulation of Urban Mobility (SUMO) and Network Simulator-3 (NS-3), a simulation platform is built to generate data of hotspot areas in IoT scenario. By effectively using the data generated by the communication between users in IoT scenario, the location area of the user terminal can be obtained. On this basis, the deployment problem is expressed as a mixed integer linear problem, which can be solved by Simulated Annealing (SA) method. The analysis of the results shows that, compared with the traditional method, the proposed method has faster convergence speed and better performance.
  • NETWORKS & SECURITY
    Elavarasi Gunasekaran, Vanitha Muthuraman
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    Cryptography is deemed to be the optimum strategy to secure the data privacy in which the data is encoded ahead of time before sharing it. Visual Secret Sharing (VSS) is an encryption method in which the secret message is split into at least two trivial images called ‘shares’ to cover it. However, such message are always targeted by hackers or dishonest members who attempt to decrypt the message. This can be avoided by not uncovering the secret message without the universal share when it is presented and is typically taken care of, by the trusted party. Hence, in this paper, an optimal and secure double-layered secret image sharing scheme is proposed. The proposed share creation process contains two layers such as threshold-based secret sharing in the first layer and universal share based secret sharing in the second layer. In first layer, Genetic Algorithm (GA)is applied to find the optimal threshold value based on the randomness of the created shares. Then, in the second layer, a novel design of universal share-based secret share creation method is proposed. Finally, Opposition Whale Optimization Algorithm (OWOA)-based optimal key was generated for rectange block cipher to secure each share. This helped in producing high quality reconstruction images. The researcher achieved average experimental outcomes in terms of PSNR and MSE values equal to 55.154225 and 0.79365625 respectively. The average PSNRwas less (49.134475) and average MSE was high (1) in case of existing methods.
  • NETWORKS & SECURITY
    Zhiwei Wang, Nianhua Yang, Qingqing Chen, Wei Shen, Zhiying Zhang
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    For the goals of security and privacy preservation, we propose a blind batch encryption- and public ledger-based data sharing protocol that allows the integrity of sensitive data to be audited by a public ledger and allows privacy information to be preserved. Data owners can tightly manage their data with efficient revocation and only grant one-time adaptive access for the fulfillment of the requester. We prove that our protocol is semanticallly secure, blind, and secure against oblivious requesters and malicious file keepers. We also provide security analysis in the context of four typical attacks.