Subjects -> COMMUNICATIONS (Total: 518 journals)
    - COMMUNICATIONS (446 journals)
    - DIGITAL AND WIRELESS COMMUNICATION (31 journals)
    - HUMAN COMMUNICATION (19 journals)
    - MEETINGS AND CONGRESSES (7 journals)
    - RADIO, TELEVISION AND CABLE (15 journals)

DIGITAL AND WIRELESS COMMUNICATION (31 journals)

Showing 1 - 31 of 31 Journals sorted alphabetically
Ada : A Journal of Gender, New Media, and Technology     Open Access   (Followers: 22)
Advances in Image and Video Processing     Open Access   (Followers: 24)
Communications and Network     Open Access   (Followers: 13)
E-Health Telecommunication Systems and Networks     Open Access   (Followers: 3)
EURASIP Journal on Wireless Communications and Networking     Open Access   (Followers: 14)
Future Internet     Open Access   (Followers: 87)
Granular Computing     Hybrid Journal  
IEEE Transactions on Wireless Communications     Hybrid Journal   (Followers: 26)
IEEE Wireless Communications Letters     Hybrid Journal   (Followers: 42)
IET Wireless Sensor Systems     Open Access   (Followers: 18)
International Journal of Communications, Network and System Sciences     Open Access   (Followers: 9)
International Journal of Digital Earth     Hybrid Journal   (Followers: 15)
International Journal of Embedded and Real-Time Communication Systems     Full-text available via subscription   (Followers: 6)
International Journal of Interactive Communication Systems and Technologies     Full-text available via subscription   (Followers: 2)
International Journal of Machine Intelligence and Sensory Signal Processing     Hybrid Journal   (Followers: 3)
International Journal of Mobile Computing and Multimedia Communications     Full-text available via subscription   (Followers: 2)
International Journal of Satellite Communications and Networking     Hybrid Journal   (Followers: 39)
International Journal of Wireless and Mobile Computing     Hybrid Journal   (Followers: 8)
International Journal of Wireless Networks and Broadband Technologies     Full-text available via subscription   (Followers: 2)
International Journals Digital Communication and Analog Signals     Full-text available via subscription   (Followers: 2)
Journal of Digital Information     Open Access   (Followers: 181)
Journal of Interconnection Networks     Hybrid Journal   (Followers: 1)
Journal of the Southern Association for Information Systems     Open Access   (Followers: 2)
Mobile Media & Communication     Hybrid Journal   (Followers: 10)
Nano Communication Networks     Hybrid Journal   (Followers: 5)
Psychology of Popular Media Culture     Full-text available via subscription   (Followers: 1)
Signal, Image and Video Processing     Hybrid Journal   (Followers: 11)
Ukrainian Information Space     Open Access  
Vehicular Communications     Full-text available via subscription   (Followers: 4)
Vista     Open Access   (Followers: 4)
Wireless Personal Communications     Hybrid Journal   (Followers: 6)
Similar Journals
Journal Cover
IEEE Wireless Communications Letters
Journal Prestige (SJR): 0.678
Citation Impact (citeScore): 3
Number of Followers: 42  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Online) 2162-2337
Published by IEEE Homepage  [228 journals]
  • IEEE Wireless Communications Letters Publication Information

    • Free pre-print version: Loading...

      Pages: C2 - C2
      Abstract: null
      PubDate: THU, 08 FEB 2024 09:18:21 -04
      Issue No: Vol. 13, No. 2 (2024)
       
  • IEEE Communications Society Information

    • Free pre-print version: Loading...

      Pages: C3 - C3
      Abstract: null
      PubDate: THU, 08 FEB 2024 09:18:21 -04
      Issue No: Vol. 13, No. 2 (2024)
       
  • An Efficient Approximate EP-Based Iterative Detection and Decoding for
           Massive MIMO

    • Free pre-print version: Loading...

      Authors: Xiaosi Tan;Weiping Li;Zaichen Zhang;Xiaohu You;Chuan Zhang;
      Pages: 255 - 259
      Abstract: In this letter, an efficient approximate expectation propagation (EPA) based iterative detection and decoding (IDD) scheme named EPA-IDD is first proposed for LDPC-coded massive MIMO systems. EPA is applied in IDD to bypass the variance updates in the inner loops, which reduces matrix inversions, simplifies extrinsic messages, and effectively enhance the convergence performance of IDD. In addition, a partial resetting scheme is proposed to efficiently adopt the decoder output into the EPA detector. A Neumann series based approximation called wNSA-EPA-IDD is further developed to reduce complexity. Numerical results show that the proposed EPA-IDD schemes outperform the state-of-the-art (SOA) double EP (DEP) in various LDPC-coded MIMO scenarios. Complexity analysis is presented to validate the improved efficiency of the proposed algorithms.
      PubDate: WED, 30 AUG 2023 10:02:26 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A Partitioned-IRS Assisted Transmit GSSK Scheme for Wireless Communication
           System

    • Free pre-print version: Loading...

      Authors: Liping Xiong;Yuyang Peng;Juho Lee;
      Pages: 260 - 264
      Abstract: In this letter, we present a partitioned intelligent reflecting surface assisted transmit generalized space shift keying (PIRS-TGSSK) scheme, in which the IRS is divided into groups corresponding to the transmit antennas and the generalized space shift keying (GSSK) is used to improve spectral efficiency (SE). The theoretical average bit error rate (ABER) of the proposed scheme is derived, using the maximum likelihood (ML) detector. In order to achieve better ABER performance and SE, we further propose a partitioned intelligent reflecting surface assisted flexible generalized space shift keying (PIRS-FGSSK) scheme where the number of activated antennas is flexible in the data transmission. In addition, the computational complexity is also analyzed. Monte Carlo simulations show that the ABER performance has been significantly improved by partitioning the IRS. Moreover, the PIRS-FGSSK with the antenna selection method achieves better ABER and SE performance for the system.
      PubDate: FRI, 22 SEP 2023 09:18:03 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Extended Variable Active Antenna Generalized Spatial Modulation

    • Free pre-print version: Loading...

      Authors: Feifei Zhu;Han Hai;Yuyang Peng;Jia Hou;Xue-Qin Jiang;
      Pages: 265 - 269
      Abstract: In this letter, a novel scheme which is called extended variable active antenna generalized spatial modulation (EV-GSM) to achieve the transmission of more extra bits of information is proposed. Firstly, the transmission mode of variable active antennas is determined according to the transmitting antenna. Then, to eliminate detection ambiguity at the detector, after selecting a specific transmission scheme, the sum of the number of bits required for the variable active antenna combination and different modulation symbols is a positive integer. In addition, we analyze the theoretical upper bound of the average bit error probability (ABEP) and the computational complexity of the detection side. Finally, Monte Carlo simulation results show that the bit error rate (BER) performance of the EV-GSM scheme using the maximum likelihood (ML) detection algorithm is better than the traditional spatial modulation scheme, and computational complexity can be reduced under the same conditions.
      PubDate: TUE, 03 OCT 2023 09:18:13 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Priority Aggregation Network With Integrated Computation and Sensation for
           Ultra Dense Artificial Intelligence of Things

    • Free pre-print version: Loading...

      Authors: Chao Ren;Zongrui He;Yingqi Li;Difei Cao;Haijun Zhang;Arumugam Nallanathan;
      Pages: 270 - 273
      Abstract: In the realm of ultra dense Intelligence of Things, efficient utilization of computation and sensation (CAS) resources remains a challenge due to their uneven temporal and spatial distribution. Priority Aggregation Network (PAN) is introduced to employ priority as an intermediary to restore, combine, and exchange idle CAS resources’ permissions for cross-temporal and cross-modal resource leasing. PAN awards priority to devices that lease their sensing and computing resources to others, facilitating efficient resource allocation. Numerical results indicate PAN maintains high cross-temporal task completion rates while conserving equipment resources, with increased willingness to pay for resources.
      PubDate: WED, 11 OCT 2023 09:17:54 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • On the Physical Layer Security of UAV-Aided Backscatter Communications

    • Free pre-print version: Loading...

      Authors: Bin Rao;Jie Hu;Azzam Al-Nahari;Kun Yang;Riku Jäntti;
      Pages: 274 - 278
      Abstract: In this letter, we investigate the issue of physical layer security in unmanned aerial vehicle (UAV)-assisted backscatter communication. The scenario involves a single UAV, a single passive backscatter device (BD), in the presence of a single eavesdropper (ED) attempting to intercept the backscattered information from the BD. To counteract the ED’s efforts, we propose an artificial noise (AN) injection scheme to degrade the ED link. We aim to maximize the secrecy rate of the BD by optimizing three key factors: the UAV’s hovering position, the power allocation factor, and the reflection coefficient of the BD. For this system setting, we derive the secrecy rate and formulate an optimization problem to optimize these variables. Due to the non-convex nature of the problem, we design an iterative algorithm based on the alternating optimization (AO) algorithm for maximizing the secrecy rate. Additionally, we provide insights into the impact of various system parameters on the overall performance. Notably, we demonstrate that the power allocation factor and the hovering altitude of the UAV play important roles for achieving secure communication.
      PubDate: TUE, 17 OCT 2023 09:17:32 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Preamble Detection in Asynchronous Random Access Using Deep Learning

    • Free pre-print version: Loading...

      Authors: Muhammad Usman Khan;Enrico Testi;Enrico Paolini;Marco Chiani;
      Pages: 279 - 283
      Abstract: Grant-free random access protocols are among the enabling techniques for massive machine-type communications, where a large number of devices activate sporadically and transmit short packets, typically containing a preamble (or a pilot sequence), without any resource allocation from the base station (BS). One of the critical tasks to be accomplished by the BS is thus the preamble-based detection of the transmitted packets. This letter proposes a deep learning (DL)-based solution for detecting preambles in an asynchronous grant-free random access uplink scenario, assuming multiple antennas at the BS. The DL-based approach outperforms the classical correlator-based approach.
      PubDate: THU, 19 OCT 2023 09:16:52 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Enhancing Reliability in Multimodal UAV Communication Based on
           Opportunistic Task Space

    • Free pre-print version: Loading...

      Authors: Chao Ren;Chao Gong;Difei Cao;Yingqi Li;Haijun Zhang;Arumugam Nallanathan;
      Pages: 284 - 287
      Abstract: An opportunistic task space-based model is proposed to enhance reliability in the execution of unmanned aerial vehicle (UAV) tasks. The task information consists of predefined basic information units, and multimodal communication is realized by sharing and transferring modality information against the interference from task-irrelevant information. The multimodal task information alignment and task-oriented multimodal non-intersecting mapping are also used to align and enhance the reliability of task-specific information from different modalities. Numerical results are provided to demonstrate the effectiveness of task space searching and its impact on task reliability.
      PubDate: THU, 19 OCT 2023 09:16:52 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Joint Beamforming for RIS-Assisted Integrated Communication, Sensing and
           Power Transfer Systems

    • Free pre-print version: Loading...

      Authors: Yue Yang;Hui Gao;Xiaoyu Yang;Ruohan Cao;Yongjian Fan;
      Pages: 288 - 292
      Abstract: This letter studies a reconfigurable intelligent surface (RIS)-aided integrated communication, sensing and power transfer systems. We aim to maximize the received energy from the energy harvester by jointly optimizing the (active) transmit beamforming at the BS and (passive) reflect beamforming by the phase shift of the RIS, subject to the Cramér-Rao bound for the target, the received signal-to-noise ratio (SNR) at the information decoding receiver and the transmit power constraint at the BS. To solve this non-convex problem with coupled variables, we decouple it into two subproblems and introduce an alternating optimization framework. The transmit beamforming sub-problem is recast into a convex form using the Schur complement and semidefinite relaxation techniques. Subsequently, auxiliary variables are introduced to transform the phase shift sub-problem into a convex problem. Simulation results show that the proposed algorithm can significantly improve the received energy while ensuring communication and sensing performance.
      PubDate: WED, 25 OCT 2023 09:16:46 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Reflecting Elements Analysis for Secure and Energy-Efficient UAV-RIS
           System With Phase Errors

    • Free pre-print version: Loading...

      Authors: Danyu Diao;Buhong Wang;Kunrui Cao;Beixiong Zheng;Runze Dong;Tianhao Cheng;Jingyu Chen;
      Pages: 293 - 297
      Abstract: This letter investigates the minimum number of reflecting elements to achieve secure and energy-efficient unmanned aerial vehicle (UAV)-reconfigurable intelligent surface (RIS) systems. Specifically, we consider a UAV equipped with a RIS as a passive relay to assist communication from a source to users while avoiding terrestrial eavesdroppers. Taking account into phase estimation errors caused by imperfect conditions such as UAV jitter, the minimum number of reflecting elements under secrecy and energy efficiency constraints is derived in closed form. Our simulation results verify the correctness of theoretical derivation and demonstrate that the UAV-RIS systems outperform terrestrial RIS systems. Our research provides theoretical guidance for configuring reflecting elements in practical UAV-RIS systems.
      PubDate: WED, 25 OCT 2023 09:16:46 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Differential Phase Shift Keying-Aided Multi-Mode Chirp Spread Spectrum
           Modulation

    • Free pre-print version: Loading...

      Authors: Xiao Yu;Xiangming Cai;Weikai Xu;Haixin Sun;Lin Wang;
      Pages: 298 - 302
      Abstract: Long-range (LoRa) radio technology is one of the most prominent choices for the low-power wide area networks (LPWANs) applications. The LoRa technology enables long-range communications while effectively minimizing energy consumption and costs. However, the existing LoRa schemes suffer from low spectral efficiency and show a degraded bit-error-rate (BER) performance. To tackle this issue, in this letter, we propose a differential phase shift keying-aided multi-mode chirp spread spectrum (DPSK-MM-CSS) scheme. The proposed DPSK-MM-CSS scheme allows for information transmission not only by the frequency shifts of the multiple multiplexed chirp signals but also by the DPSK symbols, thereby significantly improving the spectral efficiency. Furthermore, we propose a low-complexity non-coherent detection algorithm for the DPSK-MM-CSS scheme. We also compare the spectral efficiency and BER performance of DPSK-MM-CSS with that of benchmark schemes. Comparison results indicate that the proposed DPSK-MM-CSS scheme, without requiring channel state information (CSI), can achieve a comparable BER performance and significantly higher spectral efficiency compared to the existing benchmark schemes.
      PubDate: WED, 25 OCT 2023 09:16:46 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Deep Learning-Based Hybrid Precoding for RIS-Aided Broadband Terahertz
           Communication Systems in the Face of Beam Squint

    • Free pre-print version: Loading...

      Authors: Qijiang Yuan;Lixia Xiao;Chunlin He;Pei Xiao;Tao Jiang;
      Pages: 303 - 307
      Abstract: In this letter, we design a wideband hybrid reconfigurable intelligent surface network (WHRIS-Net) based on deep learning for reconfigurable intelligent surface (RIS)-assisted terahertz massive multiple-input multiple-output systems with beam squint. Firstly, the mean channel covariance matrices (MCCMs) from the base station to the RIS and from the RIS to the user are used as the inputs of WHRIS-Net. Then, a Phase-Net is applied to calculate the frequency-independent analog precoder and the phases of RIS elements. Finally, a Digital-Net designs the frequency-dependent digital precoder utilizing the MCCMs and the outputs of Phase-Net. Numerical simulations validate the effectiveness of the WHRIS-Net in terms of the sum rate and demonstrate its promising performance gain despite reduced average running time and feedback overhead.
      PubDate: MON, 30 OCT 2023 09:18:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Energy Efficiency Optimization for Subterranean LoRaWAN Using a
           Reinforcement Learning Approach: A Direct-to-Satellite Scenario

    • Free pre-print version: Loading...

      Authors: Kaiqiang Lin;Muhammad Asad Ullah;Hirley Alves;Konstantin Mikhaylov;Tong Hao;
      Pages: 308 - 312
      Abstract: The integration of subterranean LoRaWAN and non-terrestrial networks (NTN) delivers substantial economic and societal benefits in remote agriculture and disaster rescue operations. The LoRa modulation leverages quasi-orthogonal spreading factors (SFs) to optimize data rates, airtime, coverage and energy consumption. However, it is still challenging to effectively assign SFs to end devices for minimizing co-SF interference in massive subterranean LoRaWAN NTN. To address this, we investigate a reinforcement learning (RL)-based SFs allocation scheme to optimize the system’s energy efficiency (EE). To efficiently capture the device-to-environment interactions in dense networks, we proposed an SFs allocation technique using the multi-agent dueling double deep Q-network (MAD3QN) and the multi-agent advantage actor-critic (MAA2C) algorithms based on an analytical reward mechanism. Our proposed RL-based SFs allocation approach evinces better performance compared to four benchmarks in the extreme underground direct-to-satellite scenario. Remarkably, MAD3QN shows promising potentials in surpassing MAA2C in terms of convergence rate and EE.
      PubDate: THU, 26 OCT 2023 09:19:31 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Online Learning-Induced Port Selection for Fluid Antenna in Dynamic
           Channel Environment

    • Free pre-print version: Loading...

      Authors: Jiaqi Zou;Songlin Sun;Chao Wang;
      Pages: 313 - 317
      Abstract: To expand the degrees of freedom and achieve additional gains beyond multiple-input multiple-output (MIMO), the fluid antenna system (FAS) has been regarded as a potential approach for exploiting spatial diversity by reconfigurable position-switchable antennas. In the operation of FAS, port selection is one of the key challenges, demanding substantial channel training overhead. In this letter, we propose a novel online learning framework to address the port selection issue without the instantaneous full channel state information (CSI) in time-varying channel conditions. Based on bandit learning, the proposed approach learns the optimal port selection by dynamically interacting with the varying channels. The proposed algorithm is proved to achieve guaranteed performance with a bounded deviation and simulation results confirm comparable performance by comparing with the ideal optimal selections.
      PubDate: MON, 30 OCT 2023 09:18:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Detecting Abrupt Change of Channel Covariance Matrix in IRS-Assisted
           Communication

    • Free pre-print version: Loading...

      Authors: Runnan Liu;Liang Liu;Yin Xu;Dazhi He;Wenjun Zhang;Chang Wen Chen;
      Pages: 318 - 322
      Abstract: The knowledge of channel covariance matrices is crucial to the design of intelligent reflecting surface (IRS) assisted communication. However, channel covariance matrices may change suddenly in practice. This letter focuses on the detection of the above change in IRS-assisted communication. Specifically, we consider the uplink communication system consisting of a single-antenna user (UE), an IRS, and a multi-antenna base station (BS). We first categorize two types of channel covariance matrix changes based on their impact on system design: Type I change, which denotes the change in the BS receive covariance matrix, and Type II change, which denotes the change in the IRS transmit/receive covariance matrix. Secondly, a powerful method is proposed to detect whether a Type I change occurs, a Type II change occurs, or no change occurs. The effectiveness of our proposed scheme is verified by numerical results.
      PubDate: MON, 30 OCT 2023 09:18:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Beam Selection and Power Allocation: Using Deep Learning for
           Sensing-Assisted Communication

    • Free pre-print version: Loading...

      Authors: Leyan Chen;Kai Liu;Zhibo Zhang;Baoqi Li;
      Pages: 323 - 327
      Abstract: Sensing-assisted communication is a feasible technology for the rapid development of 5G and 6G communication systems, which can achieve greater channel capacity with limited energy consumption. In this letter, we propose a deep learning-based beam selection and power allocation algorithm (DL-BSPA), which includes a beam selection network and a power allocation network. The beam selection network uses real millimeter wave radar data to learn how to accurately and efficiently select beams. An unsupervised power allocation network learns and optimizes the power allocation based on the results of the beam selection network. In addition, the DL-BSPA algorithm adopts the joint deployment optimization method to maximize the channel capacity between mobile users and base stations (BS). Simulation results show that the proposed scheme is robust and can achieve competitive performance.
      PubDate: MON, 30 OCT 2023 09:18:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • IRS Auxiliary UAV Communications: Channel Modeling and Performance
           Analysis

    • Free pre-print version: Loading...

      Authors: Wendi Zhang;Zhuxian Lian;Yajun Wang;Si Li;Bibo Zhang;Zhiqiang Gai;
      Pages: 328 - 332
      Abstract: In this letter, based on the theory of electromagnetic (EM) wave, an intelligent reflecting surface (IRS) assisted channel model for unmanned aerial vehicle (UAV) communications is proposed. The proposed model reveals the relationship between the received signal power of the IRS and the horizontal rotation angle, the size, and the reflection phases of IRS reflection units. The reflection phases are designed to ensure all signals reflected by IRS are phase aligned, and the theoretical result of the received signal power of IRS assisted link is in direct proportion to the square of the total geometric area of the IRS, which accords with the measurement results obtained in the real outdoor scene. In this letter, the smallest geometric area of the IRS, for which the path loss of the IRS-assisted link is equal to that of the direct link, is investigated. With the increase of the carrier frequency, the smallest geometric area gradually decreases. Finally, we investigate the ergodic sum capacity and obtain the closed-form tight upper bound, which is validated through Monte-Carlo simulation results.
      PubDate: TUE, 31 OCT 2023 09:16:54 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Tensor-Based Channel Estimation and Data-Aided Tracking in IRS-Assisted
           MIMO Systems

    • Free pre-print version: Loading...

      Authors: Kenneth B. A. Benício;André L. F. de Almeida;Bruno Sokal;Fazal-E-Asim;Behrooz Makki;Gábor Fodor;
      Pages: 333 - 337
      Abstract: This letter proposes a framework for parameter estimation and data detection in the uplink of IRS-assisted MIMO systems in the presence of channel aging. First, we model the received pilot signal as a tensor to estimate the channel parameters and to design the IRS phase shifts. Then, our proposed tensor approach tracks the aging process to jointly estimate the aged components and the transmitted data. Compared to state-of-the-art schemes, the numerical results show that our proposed solution improves the performance of IRS-assisted MIMO systems in terms of normalized mean squared error and bit error ratio.
      PubDate: TUE, 31 OCT 2023 09:16:54 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Performance Enhancement of Codebook-Based Beamforming Using Least Squares
           Approach

    • Free pre-print version: Loading...

      Authors: Seung Joon Lee;
      Pages: 338 - 342
      Abstract: A codebook-based approach for channel estimation and beamforming affords the advantage of low complexity; however, it suffers from limited resolution of estimated directional angles of a channel owing to its finite size. To resolve this problem in codebook-based systems, this letter proposes a novel approach that employs the least squares (LS) method to estimate a directional angle from the measured beam gains of a few codewords, enhancing channel estimation performance. A nonlinear LS problem is formulated and solved using a grid search method. The impacts of grid resolution and number of codewords used on the LS estimation performance are investigated. Computer simulations demonstrate that the proposed scheme outperforms conventional schemes in terms of channel estimation errors and achieved beam gains. Furthermore, the proposed scheme requires a training overload of fewer or an equal number of codewords to measure beam gains to estimate a directional angle, compared with conventional schemes that seek to address the same problem of limited resolution in channel estimation.
      PubDate: WED, 01 NOV 2023 09:17:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Transformer-Based Efficient CSI Feedback for THz Band FDD MIMO Systems

    • Free pre-print version: Loading...

      Authors: Dong Jin Ji;Byung Chang Chung;
      Pages: 343 - 346
      Abstract: Machine learning algorithms have been extensively explored for the feedback of multiple-input multiple-output (MIMO) channel state information (CSI) in orthogonal frequency division multiplexing (OFDM) systems. However, their viability in sixth-generation (6G) wireless communication systems, operating in the terahertz (THz) band, remains uncertain. To address this, we propose ChannelTransformer, a transformer-model-based CSI feedback scheme that incorporates multi-head self-attention and a CSI-feedback-aware transformer structure, and a lightweight user equipment (UE) model. Through simulations in the DeepMIMO O1 scenario at 140GHz, ChannelTransformer demonstrates superior performance in terms of normalized mean square error (NMSE) and cosine similarity across various feedback lengths compared to conventional schemes with a much smaller UE model size.
      PubDate: WED, 01 NOV 2023 09:17:59 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A Meta-Learning-Based Precoder Optimization Framework for Rate-Splitting
           Multiple Access

    • Free pre-print version: Loading...

      Authors: Rafael Cerna Loli;Bruno Clerckx;
      Pages: 347 - 351
      Abstract: In this letter, we propose the use of a meta-learning based precoder optimization framework to directly optimize the Rate-Splitting Multiple Access (RSMA) precoders with partial Channel State Information at the Transmitter (CSIT). By exploiting the overfitting of the compact neural network to maximize the explicit Average Sum-Rate (ASR) expression, we effectively bypass the need for any other training data while minimizing the total running time. Numerical results reveal that the meta-learning based solution achieves similar ASR performance to conventional precoder optimization in medium-scale scenarios, and significantly outperforms sub-optimal low complexity precoder algorithms in the large-scale regime.
      PubDate: WED, 01 NOV 2023 09:17:59 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Transmitter Side Beyond-Diagonal Reconfigurable Intelligent Surface for
           Massive MIMO Networks

    • Free pre-print version: Loading...

      Authors: Anup Mishra;Yijie Mao;Carmen D’Andrea;Stefano Buzzi;Bruno Clerckx;
      Pages: 352 - 356
      Abstract: This letter focuses on a transmitter or base station (BS) side beyond-diagonal reflecting intelligent surface (BD-RIS) deployment strategy to enhance the spectral efficiency (SE) of a time-division-duplex massive multiple-input multiple-output (MaMIMO) network. In this strategy, the active antenna array utilizes a BD-RIS at the BS to serve multiple users in the downlink. Based on the knowledge of statistical channel state information (CSI), the BD-RIS coefficients matrix is optimized by employing a novel manifold algorithm, and the power control coefficients are then optimized with the objective of maximizing the minimum SE. Through numerical results we illustrate the SE performance of the proposed transmission framework and compare it with that of a conventional MaMIMO transmission for different network settings.
      PubDate: FRI, 03 NOV 2023 09:16:56 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • JCNN-Based DD Hybrid Precoding Algorithm With TPSAS Structure for FD-MIMO
           Systems

    • Free pre-print version: Loading...

      Authors: Baozhu Shi;Fulai Liu;Ruiyan Du;
      Pages: 357 - 361
      Abstract: This letter presents a joint convolutional neural network (JCNN)-based double dimensional (DD) hybrid precoding algorithm for adaptive fully-connected subarray structure with two-layer shared phase shifters (TPSAS) full-dimensional multiple-input multiple-output (FD-MIMO) systems. Firstly, a TPSAS structure is developed to reduce hardware complexity. Then, a novel JCNN is designed to learn predicting the vectorized hybrid precoder with the vertical phase subnetwork (VpsCNN) and horizontal phase subnetwork (HpsCNN). Furthermore, the JCNN is trained by a label and a two-stage training strategy. In the first stage, minimizing residual between hybrid precoder and the label is adopted to train the JCNN. Specially, two distinct network layers are applied to meet constraints of VpsCNN and HpsCNN, respectively, including unit modulus and custom phase layers. In the second stage, estimated channel matrices are sent into the well-trained JCNN to simultaneously obtain the vertical precoder, horizontal precoder, and digital precoder. The theoretical analyses and simulation results verify that the proposed algorithm better trades off between spectral efficiency and hardware complexity than other algorithms while enhancing energy efficiency obviously.
      PubDate: WED, 01 NOV 2023 09:17:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Revealing the Impact of Beamforming in ISAC

    • Free pre-print version: Loading...

      Authors: Chongjun Ouyang;Yuanwei Liu;Xingqi Zhang;
      Pages: 362 - 366
      Abstract: This letter proposes advanced beamforming design and analyzes its influence on the sensing and communications (S&C) performance for a multiple-antenna integrated S&C (ISAC) system with a single communication user and a single target. Novel closed-form beamformers are derived for three typical scenarios, including the sensing-centric design, communications-centric design, and Pareto optimal design. Regarding each scenario, the outage probability, ergodic communication rate (CR), and sensing rate (SR) are analyzed to derive the diversity orders and high signal-to-noise ratio slopes. Numerical results are provided to demonstrate that i) beamforming design can affect the high-SNR power offset and diversity order but does not influence the high-SNR slope; ii) ISAC exhibits larger high-SNR slopes and a more extensive SR-CR region than conventional frequency-division S&C (FDSAC) techniques.
      PubDate: WED, 01 NOV 2023 09:17:59 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Asynchronous Grant-Free Massive Access With Doppler Frequency Offset in
           NTN

    • Free pre-print version: Loading...

      Authors: Yang Li;Shuyi Chen;Weixiao Meng;
      Pages: 367 - 371
      Abstract: Grant-free-based non-terrestrial networks (GF-NTN) enable wide-area coverage for low-cost and energy-limited devices in Internet-of-Things (IoT). However, the estimation of active devices and channels faces challenges due to the dual impact of propagation delay and Doppler frequency offset (DFO). To address this challenge, we propose an effective detection algorithm aiming to improve the estimation accuracy by exploiting the intrinsic properties in GF-NTN. A structured sparsity model is developed to capture the channel properties in delay-Doppler-time (DDT) domain. Simulation results confirm that the proposed algorithms outperform the state-of-the-art approaches confronted with large latency and severe Doppler effect.
      PubDate: WED, 01 NOV 2023 09:17:58 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Novel Expressions for the Outage Probability and Diversity Gains in Fluid
           Antenna System

    • Free pre-print version: Loading...

      Authors: José David Vega-Sánchez;Arianna Estefanía López-Ramírez;Luis Urquiza-Aguiar;Diana Pamela Moya Osorio;
      Pages: 372 - 376
      Abstract: The flexibility and reconfigurability at the radio frequency (RF) front-end offered by the fluid antenna system (FAS) make this technology promising for providing remarkable diversity gains in networks with small and constrained devices. Toward this direction, this letter compares the outage probability (OP) performance of non-diversity and diversity FAS receivers undergoing spatially correlated Nakagami- ${m}$ fading channels. Although the system properties of FAS incur in complex analysis, we derive a simple yet accurate closed-form approximation by relying on a novel asymptotic matching method for the OP of a maximum-gain combining-FAS (MGC-FAS). The approximation is performed in two stages, the approximation of the cumulative density function (CDF) of each MGC-FAS branch, and then the approximation of the end-to-end CDF of the MGC-FAS scheme. With these results, closed-form expressions for the OP and the asymptotic OP are derived. Finally, numerical results validate our approximation of the MGC-FAS scheme and demonstrate its accuracy under different diversity FAS scenarios.
      PubDate: FRI, 03 NOV 2023 09:16:56 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A Simple Method for the Performance Analysis of Fluid Antenna Systems
           Under Correlated Nakagami-m Fading

    • Free pre-print version: Loading...

      Authors: José David Vega-Sánchez;Luis Urquiza-Aguiar;Martha Cecilia Paredes Paredes;Diana Pamela Moya Osorio;
      Pages: 377 - 381
      Abstract: By recognizing the tremendous flexibility of the emerging fluid antenna system (FAS), which allows dynamic reconfigurability of the location of the antenna within a given space, this letter investigates the performance of a single-antenna FAS over spatially correlated Nakagami- ${m}$ fading channels. Specifically, simple and highly accurate closed-form approximations for the cumulative density function of the FAS channel and the outage probability of the proposed system are obtained by employing a novel asymptotic matching method, which is an improved version of the well-known moment matching. With this method, the outage probability can be computed simply without incurring complex multi-fold integrals, thus requiring negligible computational effort. Finally, the accuracy of the proposed approximations is validated, and it is shown that the FAS can meet or even exceed the performance attained by the conventional maximal ratio combining (MRC) technique.
      PubDate: FRI, 03 NOV 2023 09:16:56 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • New Exact Higher Order Moment Expressions for the PAPR of Complex Gaussian
           Variables

    • Free pre-print version: Loading...

      Authors: Ranjan K. Mallik;Ross Murch;
      Pages: 382 - 386
      Abstract: New analytical expressions for the moment of the peak to average power ratio (PAPR) of ${n}$ independent and identically distributed (i.i.d.) zero-mean complex circular Gaussian random variables (r.v.s) are derived. These expressions give the higher order moments. For an orthogonal frequency division multiplexing (OFDM) system with ${n}$ subcarriers, the ${n}$ samples in each OFDM symbol are taken as i.i.d. with each following a zero-mean complex circular Gaussian distribution. The PAPR statistics of these samples play an important role as performance metrics. An exact closed form expression for the $\ell $ th moment of the PAPR obtained in earlier work is used to derive a compact expression and a simple expression in terms of a function $H_{n}(-\ell)$ ; an alternative expression for $H_{n}(-\ell)$ is also presented. The variance obtained from the $\ell $ th moment is shown to be asymptotically equal to a previous result for a large number of r.v.s.
      PubDate: FRI, 03 NOV 2023 09:16:56 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Model-Driven IEP-GNN Framework for MIMO Detection With Bayesian
           Optimization

    • Free pre-print version: Loading...

      Authors: Zishen Liu;Dongxuan He;Nan Wu;Qinsiwei Yan;Yonghui Li;
      Pages: 387 - 391
      Abstract: In this letter, a model-driven detector called IEP-GNN is proposed for massive multiple-input and multiple-output (MIMO) systems. Graph neural network (GNN) and improved moment matching (IMM) are integrated into the expectation propagation (EP) algorithm to improve the accuracy of posterior distribution approximation and leverage the self-correction ability of EP algorithm. Moreover, to acquire the training experiences and optimize initial parameters, hotbooting and Bayesian parameter optimization (BPO) are employed respectively, which can further improve the performance of the proposed IEP-GNN. Simulation results show that our proposed IEP-GNN with BPO outperforms other state-of-the-art EP-based detectors while maintaining an acceptable convergence and computational complexity.
      PubDate: FRI, 03 NOV 2023 09:16:56 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Novel Channel Aware Power Control for a Multi-User Downlink NOMA Network

    • Free pre-print version: Loading...

      Authors: Anand Jee;Shankar Prakriya;
      Pages: 392 - 396
      Abstract: In this letter, we consider a downlink multi-user (MU) non-orthogonal multiple access (NOMA) network. We demonstrate that utilizing knowledge of the channel gains to determine the NOMA power allocation coefficients can dramatically improve throughput performance. Considering practical imperfect successive interference cancellation, expressions are derived for the optimum power allocation that ensures the minimum outage probability for the signalling scheme. The level of successive interference cancellation at each user and the decoding order are specified. It is shown that the proposed decoding order and the power allocations result in the maximum throughput. Expressions are derived for the throughput with these power allocations. Channel knowledge is exploited to determine the minimum power required for non-outage, and an expression is derived for the average value of this minimum power requirement. Computer simulations validate the derived expressions.
      PubDate: MON, 06 NOV 2023 09:18:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A Scalable Energy Consumption Optimization in Downlink Cell-Free Massive
           MIMO

    • Free pre-print version: Loading...

      Authors: Yijie Gao;Peng Cheng;Zhuo Chen;Khoa Tran Phan;Wei Xiang;Yi-Ping Phoebe Chen;
      Pages: 397 - 401
      Abstract: Cell-free multiple-input multiple-output (MIMO) eliminates inter-cell interference by cooperatively serving users through distributed access points (APs). Energy efficiency is critical as an individual backhaul link is required to connect each AP to a central processing unit (CPU), and hardware static power supplies and wireless signal transmissions consume huge amounts of energy. AP selection is promising to optimize energy efficiency, where some APs can be deactivated when a large portion of users experience notable propagation loss. However, AP selection alone cannot ensure the minimal rate requirement when the number of users is comparable to or exceeds that of APs. To address this, we propose a scalable energy consumption optimization method by jointly optimizing power allocation, AP selection, and user grouping. We formulate an optimization problem that involves both continuous power allocation variables and discrete AP selection/user grouping variables. We propose a low-complexity method that breaks down the optimization problem into two stages: 1) iteratively refined grouping based on the proposed minimal rate maximization criterion and 2) joint power allocation and AP selection. Numerical results show that the proposed method significantly outperforms several baselines.
      PubDate: MON, 06 NOV 2023 09:18:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Generalized Optimization Method of Placement and Beamforming Design for
           Multiuser MIMO UAV Communications

    • Free pre-print version: Loading...

      Authors: Cheng Zeng;Jun-Bo Wang;Ming Xiao;Yijin Pan;Yijian Chen;Hongkang Yu;Jiangzhou Wang;
      Pages: 402 - 406
      Abstract: In this letter, we investigate the integration of multiuser multiple-input multiple-output (MU-MIMO) technologies with unmanned aerial vehicle (UAV) communications. We jointly optimize the placement and the MU-MIMO beamforming matrix of the UAV for maximization of the sum rate of all users. Due to the complexity of MIMO rate expression and matrix inversion operation, we propose a generalized transformation method to decouple the variables and find an equivalent tractable function of the MIMO rate for the original problem based on weighted minimum mean square error (WMMSE) methods. To solve the problem, an alternating algorithm combined with the Lagrange dual method is proposed where the semi-closed-form solutions for UAV placement and beamforming scheme are obtained at each step. Simulation results verify the effectiveness of the proposed method and show that the MU-MIMO technique can significantly improve performance in UAV networks.
      PubDate: MON, 06 NOV 2023 09:18:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • 5G New Radio Compliant IQI Compensation

    • Free pre-print version: Loading...

      Authors: Enrique T. R. Pinto;Visa Tapio;Markku Juntti;
      Pages: 407 - 411
      Abstract: The 5G New Radio (NR) standard allows for the utilization of mmWave band to achieve multi-Gbps throughput and low latency. However, radio transceivers are much more sensitive to hardware imperfections such as phase noise and IQ imbalance (IQI) at higher frequencies. Particularly, IQI can severely deteriorate the thorughput of radio links by increasing symbol error rates. This letter proposes a receiver IQI compensation procedure using exclusively the 5G NR reference signals. It is shown that the new method has the capability of outperforming existing procedures while requiring no previous information about the IQI parameters or the channel.
      PubDate: MON, 06 NOV 2023 09:18:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • NOMA-Assisted Grant-Free Transmission: How to Design Pre-Configured SNR
           Levels'

    • Free pre-print version: Loading...

      Authors: Zhiguo Ding;Robert Schober;H. Vincent Poor;
      Pages: 412 - 416
      Abstract: The key idea of non-orthogonal multiple access (NOMA) assisted grant-free transmission is to create pre-configured receive signal-to-noise ratio (SNR) levels that can be used to serve users in a way similar to conventional bandwidth resources, such as time slots and subcarriers. In the literature, there exist two different SNR-level designs, and the aim of this letter is to investigate their impact on the performance of grant-free transmission, where age-of-information is adopted as the performance metric as it captures not only failures at the physical layer, such as outages and bit errors, but also errors caused by user collisions. The presented analytical and simulation results illustrate the performance gain achieved by NOMA over orthogonal multiple access, and also reveal the relative merits of the considered designs for pre-configured SNR levels.
      PubDate: TUE, 07 NOV 2023 09:17:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Exploiting Malicious RIS for Secret Key Acquisition in Physical-Layer Key
           Generation

    • Free pre-print version: Loading...

      Authors: Lei Hu;Guyue Li;Aiqun Hu;Derrick Wing Kwan Ng;
      Pages: 417 - 421
      Abstract: Due to the capability of controlling wireless environments, reconfigurable intelligent surface (RIS) can be exploited to assist radio channel-based physical-layer key generation (PKG). However, this may also pose great security threats to PKG when it is controlled by an attacker. To this end, this letter studies a RIS leakage (RISL) attack that assists the attacker to manipulate the generated keys between the legitimate ends in PKG systems. Specifically, in block fading environments, by alternatingly adapting the RIS reflection coefficients to all 0s and 1s in each block, the received signal strength (RSS) at the legitimate ends is likely to be boosted and attenuated regularly across time, causing predictable 0s and 1s in the quantized bits. To resist this attack, we propose a countermeasure based on dynamic private pilots (CDPP) and prove that the RISL success probability can be significantly reduced by CDPP. Simulation results verify the effectiveness of the proposed attack and countermeasure, highlighting the importance of introducing artificial randomness for secret key security in block fading channels.
      PubDate: TUE, 07 NOV 2023 09:17:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Hierarchically Structured Matrix Recovery-Based Channel Estimation for
           RIS-Aided Communications

    • Free pre-print version: Loading...

      Authors: Yabo Guo;Peng Sun;Zhengdao Yuan;Qinghua Guo;Zhongyong Wang;
      Pages: 422 - 426
      Abstract: Reconfigurable intelligent surface (RIS) has emerged as a promising technology for improving capacity and extending coverage of wireless networks. In this letter, we consider RIS-aided millimeter wave (mmWave) multiple-input and multiple-output (MIMO) communications, where acquiring accurate channel state information is challenging due to the high dimensionality of channels. To achieve efficient channel estimation, fully exploiting the structures of the channels is crucial. To this end, we formulate the channel estimation as a hierarchically structured matrix recovery problem, and design a low-complexity message passing algorithm to solve it, leveraging the unitary approximate message passing. Simulation results demonstrate the superiority of the proposed algorithm with performance close to the oracle bound.
      PubDate: WED, 08 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Optimal Passive Beamforming for Reconfigurable Intelligent
           Surface-Assisted Communications With Discrete Phase Shifts

    • Free pre-print version: Loading...

      Authors: Donglai Zhao;Gang Wang;Jinlong Wang;Chenxu Wang;
      Pages: 427 - 431
      Abstract: This letter presents an optimal phase shift configuration method for Reconfigurable Intelligent Surfaces (RISs) with discrete phase shifts to maximize the passive beamforming gain. Specifically, based on theoretical analysis, the multi-ary phase shift optimization problem is first transformed into an equivalent binary phase shift problem. Although it is still a non-convex optimization problem, the optimal solution can be found indirectly through the linear search (LS) for the optimal phase of the superimposed channel. Accordingly, the LS algorithm is designed, in which iterative operations are adopted to ensure the linear computational complexity. The simulation results verify that the proposed LS algorithm achieves the globally optimal passive beamforming, which outperforms existing excellent algorithms. Furthermore, it is also revealed that a 3-bit quantized phase shifter can obtain sufficiently good performance relative to the ideal continuous phase shifter.
      PubDate: WED, 08 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Cell-Free Terahertz Networks: A Spatial-Spectral Approach

    • Free pre-print version: Loading...

      Authors: Zesheng Zhu;Lifeng Wang;Xin Wang;Bo Tan;Shi Jin;
      Pages: 432 - 436
      Abstract: Cell-free network architecture plays a promising role in the terahertz (THz) networks since it provides better link reliability and uniformly good services for all the users compared to the co-located massive MIMO counterpart, and the spatial-spectral THz link has the advantages of lower initial access latency and fast beam operations. To this end, this letter studies cell-free spatial-spectral THz networks with leaky-wave antennas, to exploit the benefits of leveraging both cell-free and spatial-spectral THz technologies. By addressing the coupling effects between propagation angles and frequencies, we propose novel frequency-dependent THz transmit antenna selection schemes to maximize the transmission rate. Numerical results confirm that the proposed antenna selection schemes can achieve much larger transmission rate than the maximal ratio transmission of using all the transmit antennas with equal subchannel bandwidth allocation in higher THz frequencies.
      PubDate: WED, 08 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Rank Optimization for MIMO Channel With RIS: Simulation and Measurement

    • Free pre-print version: Loading...

      Authors: Shengguo Meng;Wankai Tang;Weicong Chen;Jifeng Lan;Qun Yan Zhou;Yu Han;Xiao Li;Shi Jin;
      Pages: 437 - 441
      Abstract: Reconfigurable intelligent surface (RIS) is a promising technology that can reshape the electromagnetic environment in wireless networks, offering various possibilities for enhancing wireless channels. Motivated by this, we investigate the channel optimization for multiple-input multiple-output (MIMO) systems assisted by RIS. In this letter, an efficient RIS optimization method is proposed to enhance the effective rank of the MIMO channel for achievable rate improvement. Numerical results are presented to verify the effectiveness of RIS in improving MIMO channels. Additionally, we construct a $2\times 2$ RIS-assisted MIMO prototype to perform experimental measurements and validate the performance of our proposed algorithm. The results reveal a significant increase in effective rank and achievable rate for the RIS-assisted MIMO channel compared to the MIMO channel without RIS.
      PubDate: THU, 09 NOV 2023 09:16:34 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Symbol-Level Design for Joint Radar Communication Based on Directional
           Modulation

    • Free pre-print version: Loading...

      Authors: Maolin Li;Bo Zhang;Baoju Zhang;Yuan Ding;Taekon Kim;Xiaonan Zhao;
      Pages: 442 - 445
      Abstract: Direction modulation (DM) is a physical layer security (PLS) technology that has attracted extensive research. In this letter, a symbol-level design for radar communication integration systems is proposed based on DM. In the radar direction, the performance of target estimation is ensured by minimizing the Cramér-Rao bound (CRB) of sensing, while maintaining the desired constellation patterns in the communication directions and meeting the mismatch threshold with the random signal in the undesired directions, disrupting the constellation patterns. The numerical results demonstrate that the proposed method has an extremely low CRB in the radar direction and low bit error rate (BER) levels in the communication directions.
      PubDate: FRI, 10 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Reconfigurable Intelligent Surfaces: How to Enhance Multiuser Channel
           Prediction'

    • Free pre-print version: Loading...

      Authors: M. Karam Shehzad;Mohamad Assaad;Luca Rose;
      Pages: 446 - 450
      Abstract: Reconfigurable intelligent surface (RIS) is envisioned as the key enabler of a smart wireless environment, offering a nearly energy-neutral solution to control the dynamic propagation of electromagnetic signals. On the other hand, channel prediction can bring promising benefits in various aspects of wireless systems, e.g., reducing channel state information feedback overhead. Prediction of a highly dynamic channel is cumbersome. This letter focuses on enhancing the performance of multiuser channel prediction by introducing time correlation in the composite channel while exploiting quasi-RIS. We show that the intelligently configured RIS improves channel prediction performance while saving sufficient RIS elements for other applications and simplifies machine learning architecture.
      PubDate: FRI, 10 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • NEAT-MUSIC: Auto-Calibration of DOA Estimation for Terahertz-Band Massive
           MIMO Systems

    • Free pre-print version: Loading...

      Authors: Ahmet M. Elbir;Abdulkadir Celik;Ahmed M. Eltawil;
      Pages: 451 - 455
      Abstract: Terahertz (THz) band is envisioned for the future sixth generation wireless systems thanks to its abundant bandwidth and very narrow beamwidth. These features are one of the key enabling factors for high resolution sensing with milli-degree level direction-of-arrival (DOA) estimation. Therefore, this letter investigates the DOA estimation problem in THz systems in the presence of two major error sources: 1) gain-phase mismatches, which occur due to the deviations in the radio-frequency circuitry; 2) beam-squint, which is caused because of the deviations in the generated beams at different subcarriers due to ultra-wide bandwidth. An auto-calibration approach, namely NoisE subspAce correcTion technique for MUltiple SIgnal Classification (NEAT-MUSIC), is proposed based on the correction of the noise subspace for accurate DOA estimation in the presence of gain-phase mismatches and beam-squint. To gauge the performance of the proposed approach, the Cramér-Rao bounds are also derived. Numerical results show the effectiveness of the proposed approach.
      PubDate: FRI, 10 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Resolution of Near-Field Beamforming and Its Impact on NOMA

    • Free pre-print version: Loading...

      Authors: Zhiguo Ding;
      Pages: 456 - 460
      Abstract: The resolution of near-field beamforming is an important metric to measure how effectively users with different locations can be distinguished. This letter identifies the condition under which the resolution of near-field beamforming is not perfect. This imperfect resolution means that a legacy user’s preconfigured near-field beam can be still useful to other users, which motivates the application of non-orthogonal multiple access (NOMA). Both the analytical and simulation results are presented to demonstrate that indeed those near-field beams preconfigured for legacy users can be used to serve additional NOMA users effectively, which improves the overall system throughput and connectivity.
      PubDate: FRI, 10 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Deep Learning-Based Hybrid Beamforming Design for IRS-Aided MIMO
           Communication

    • Free pre-print version: Loading...

      Authors: Kenneth Ikeagu;Muhammad R. A. Khandaker;Chaoyun Song;Yuan Ding;
      Pages: 461 - 465
      Abstract: In this letter, we study an intelligent reflecting surface (IRS)-aided multiple-input multiple-output (MIMO) communication system in which a transmitter equipped with hybrid precoding architecture communicates to a receiver with hybrid combining architecture via an IRS. We propose a deep learning (DL) based approach to jointly learn and predict the features of the IRS reflection matrix and the hybrid beamformers while maximizing the spectral efficiency. To accomplish this, we first propose the alternating direction method of multipliers (ADMM) algorithm to design the IRS matrix. This matrix is then used to form an effective channel that serves as input to a two-stage neural network. The neural networks are trained sequentially to estimate the IRS matrix, as well as the hybrid precoding and combining matrices. Simulation results verify that our proposed model achieves a performance that is close to the full-digital based scheme; achieves comparable performance to some state-of-the-art algorithms while with reduced computational complexity; and outperforms the scheme implemented without an IRS.
      PubDate: FRI, 10 NOV 2023 09:16:42 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A WMMSE-Based Contiguous Resource Scheduling Algorithm for 5G-NR Uplink

    • Free pre-print version: Loading...

      Authors: Luyuan Zhang;An Liu;Xihan Chen;
      Pages: 466 - 470
      Abstract: In 5G NR, contiguous resource allocation, in which each user must be allocated with a contiguous subset of resource blocks (RBs), is expected to be followed for practical uplink scheduler to reduce the signaling overhead for scheduling. Due to the spatial-domain coupling caused by the multi-user MIMO (MU-MIMO) transmission and frequency-domain coupling caused by the contiguous resource allocation constraint, finding the optimal contiguous resource allocation in 5G-NR uplink requires exhaustive search that has exponential complexity w.r.t. the number of users and RBs. This letter presents a weighted-minimum-mean-square-error (WMMSE)-based contiguous resource scheduling algorithm, which alternatively optimizes the receive matrix, mean squared error (MSE) weight matrix and resource allocation until convergence. The resource allocation subproblem can be further decomposed into independent resource allocation subproblems for each user, whose optimal solution can be found within polynomial complexity. A low complexity resource allocation method is proposed to further reduce the complexity to satisfy the real-time scheduling requirement in 5G-NR. Experimental results show that the proposed algorithms can achieve much better scheduling performance than existing baselines with comparable complexity.
      PubDate: TUE, 14 NOV 2023 09:16:51 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Information and Energy Beamforming Optimization for Symbiotic AmBC and
           SWIPT Networks

    • Free pre-print version: Loading...

      Authors: Fatemeh Rezaei;Diluka Galappaththige;Chintha Tellambura;Amine Maaref;
      Pages: 471 - 475
      Abstract: This letter develops a symbiotic network comprising an ambient backscatter communication network and a simultaneous wireless information and power transfer (SWIPT) network. Specifically, passive tags leverage the primary signal from the full-duplex (FD) base station (BS) for energy harvesting (EH) and data transmission to the FD BS, while delivering more power to the downlink SWIPT users. To enhance the symbiosis benefits and suppress the harms between the two networks, we design uplink zero-forcing reception filters and downlink optimal energy and information beamforming at the FD BS, and optimal power splitting factor at users to maximize the tag sum signal-to-interference-plus-noise ratio, subject to the minimum rate and power requirements of the users, tags’ EH requirement and the residual self-interference constraints. Compared to random, maximum ratio transmission, and zero-forcing beamforming, our approach yields significant improvements.
      PubDate: TUE, 14 NOV 2023 09:16:51 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Low-Power Full-Duplex Self-Backhauling

    • Free pre-print version: Loading...

      Authors: Hyungseop Son;Kwonhue Choi;
      Pages: 476 - 480
      Abstract: This letter proposes a power-efficient full-duplex (FD) self-backhauling scheme for small base station (SBS) downlink cellular networks. To this end, unlike the access link where the UEs’ downlink packets are forwarded through individual subbands (SBs), the multiple UEs’ packets in the backhaul link are formatted into a single packet having a wide bandwidth. As the access link transmit (TX) power levels differ, SB by SB, each SB in the backhaul link undergoes different power levels of self-interference from the access link. Hence, backhaul link TX powers for multiple SBs are jointly optimized group-wise so total power is minimized while maintaining the same capacity as a conventional UE-wise backhaul scheme. Nominal system parameter settings achieve backhaul link power savings of more than 3 dB, and the power-saving gain even increases as the target SINR decreases or the UE grouping size increases. If additional channel gain factors (such as shadow fading) are considered, the power saving gain is further enhanced.
      PubDate: WED, 15 NOV 2023 09:16:48 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Energy-Efficient Over-the-Air Computation for Relay-Assisted IoT Networks

    • Free pre-print version: Loading...

      Authors: Junjie Wan;Jing Wen;Kunlun Wang;Qingqing Wu;Wen Chen;
      Pages: 481 - 485
      Abstract: Over-the-air computation (AirComp) utilizes the superposition of wireless multiple access channels (MAC) to achieve efficient data aggregation, which is a very effective way to achieve large-scale data transmission and edge intelligence in the intelligent Internet of Things (IoT). In this letter, we propose an amplify and forward (AF) relay-assisted two-hop AirComp system, where the AF relay is used for forwarding signals from sensors. We present the problem of minimizing the sum power (SP) of the sensors under the constraints of available relay transmit power and data aggregating mean square error (MSE). The original problem includes optimizing transmitter (Tx) scaling factor for the sensors, optimizing Tx scaling factor for the relay, and optimizing receiver (Rx) scaling factor for the fusion center (FC). To address the non-convexity of the objective function and constraints of the optimization problem, we transform the original problem into two sub-problems and solve it by iterative optimization algorithm, and each subproblem can be solved with a closed-form optimal solution. In simulations, our proposed SP minimization scheme outperforms benchmark schemes with different parameter settings.
      PubDate: WED, 15 NOV 2023 09:16:47 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Analysis of the Optimal Feedback Rate for Limited Feedback-Based Block
           Diagonalization in Cellular MU-MIMO Systems

    • Free pre-print version: Loading...

      Authors: Sungmin Lee;Moonsik Min;
      Pages: 486 - 490
      Abstract: We examine a downlink cellular network utilizing multiple-antenna base stations (BSs) deployed via a homogeneous Poisson point process. Each BS serves multiple users concurrently using spatial division multiple access (SDMA), with each user equipped with multiple receive antennas. The downlink SDMA employs linear precoding, specifically block diagonalization (BD), with channel state information obtained through limited feedback to construct BD precoding matrices. We offer close approximations for the optimal feedback rate aimed at maximizing the net spectral efficiency, which quantifies the net data rate achieved through limited-feedback-based BD. To achieve this, we introduce a novel lower bound for the Laplace transform of multi-cell interference. This analytical result aids in deriving the optimal feedback rate and the corresponding maximum net spectral efficiency. In comparison to previous studies that assumed single-antenna users, limited-feedback-based BD, enhanced by optimized feedback rates, substantially improves net sum spectral efficiency in interference-limited cellular networks. This result is remarkable as it holds true even with a reduced feedback bit requirement per data stream.
      PubDate: WED, 15 NOV 2023 09:16:48 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Code-Aided Channel Estimation in LDPC-Coded MIMO Systems

    • Free pre-print version: Loading...

      Authors: Binghui Shi;Yongpeng Wu;Peihong Yuan;Derrick Wing Kwan Ng;Xiang-Gen Xia;Wenjun Zhang;
      Pages: 491 - 495
      Abstract: For a multiple-input multiple-output (MIMO) system with unknown channel state information (CSI), a novel low-density parity check (LDPC)-coded transmission (LCT) scheme with joint pilot and data channel estimation is proposed. To fine-tune the CSI, a method based on the constraints introduced by the coded data from an LDPC code is designed such that the MIMO detector exploits the fine-tuned CSI. For reducing the computational burden, a coordinate ascent algorithm is employed along with several approximation methods, effectively reducing the required times of MIMO detection and computational complexity to achieve a satisfying performance. Simulation results utilizing WiMAX standard LDPC codes and quadrature phase-shift keying (QPSK) modulation demonstrate gains of up to 1.3 dB at a frame error rate (FER) of 10−4 compared to pilot-assisted transmission (PAT) over Rayleigh block-fading channels.
      PubDate: THU, 16 NOV 2023 09:19:45 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Gridless Hybrid-Field Channel Estimation for Extra-Large Aperture Array
           Massive MIMO Systems

    • Free pre-print version: Loading...

      Authors: Yang Xi;Fuqiang Zhu;Binggui Zhou;Ting Liu;Shaodan Ma;
      Pages: 496 - 500
      Abstract: Channel estimation is significant for extra-large aperture array (ELAA) massive multiple-input multiple-output (MIMO) systems to fully fulfill their potential. However, hybrid-field propagation environment appears due to adopting ELAA, which thereby severely degrades the performance of existing channel estimation algorithms designed based on the channel sparsity property in traditional beam/angle domains. To tackle this problem, we propose a gridless hybrid-field channel estimation algorithm in this letter by excavating the hybrid-field channel sparsity in the fractional Fourier domain. The hybrid-field channel estimation problem is first formulated, and then the discrete fractional Fourier transform (DFrFT) is introduced to reveal the channel sparsity in the fractional Fourier domain. After that, the DFrFT-based Newtonized orthogonal matching pursuit algorithm is proposed without prior knowledge of the number of propagation paths. Numerical results show that the proposed algorithm greatly outperforms the existing algorithms.
      PubDate: THU, 16 NOV 2023 09:19:45 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A Copula-Based Approach to Performance Analysis of Fluid Antenna System
           With Multiple Fixed Transmit Antennas

    • Free pre-print version: Loading...

      Authors: Yanzhao Hou;Jinghan Mao;Shunhang Zhang;Qimei Cui;Xiaofeng Tao;Weichao Li;Yu Chen;
      Pages: 501 - 504
      Abstract: Fluid antenna system (FAS), enabled by dynamic, software-defined antenna architectures, introduces a new degree of freedom (DoF) to enhance wireless communications performance. In this letter, we consider a point-to-point system where a transmitter equipped with multiple fixed antennas communicates to a mobile receiver equipped with a FAS. We investigate the outage probability performance of this system. Our analysis is based on a copula approach, which can model the correlation between the channels at different ports of FAS and permits the evaluation of the outage probability via the copula. Both student- ${t}$ and Gaussian copulas are considered. Our numerical results demonstrate that the size of FAS has a greater impact on the achievable performance than its resolution.
      PubDate: THU, 16 NOV 2023 09:19:45 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Competitive IRS Assignment for IRS-Based NOMA System

    • Free pre-print version: Loading...

      Authors: Haitham Al-Obiedollah;Haythem Bany Salameh;Kanapathippillai Cumanan;Zhiguo Ding;Octavia A. Dobre;
      Pages: 505 - 509
      Abstract: This letter considers the downlink transmission of an intelligent reflecting surface (IRS)-aided multi-carrier (MC) non-orthogonal multiple access (NOMA) system, referred to as the IRS-aided MC-NOMA system. Due to the limitations on the availability of the IRS, a limited number of channels can be served with the support of the available IRS units. Therefore, a competitive approach is proposed to assign the available IRS units for the intended channels, and to group the users in each channel (i.e., clustering). To validate the effectiveness of the proposed competitive approaches, a power minimization problem is considered that aims to minimize the total transmit power while ensuring a set of quality-of-service requirements. Because of the non-convex nature of the joint power optimization problem, we develop a simple sequential convex approximation algorithm to solve it. Simulation results demonstrate that the IRS-aided MC-NOMA system with proposed IRS-assignment and grouping approaches outperforms the random IRS-assignment and grouping approaches regarding the transmit power consumption.
      PubDate: MON, 20 NOV 2023 09:17:54 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Covert Communication Using Time Modulated Retrodirective Array

    • Free pre-print version: Loading...

      Authors: Yue Ma;Ruiqian Ma;Weiwei Yang;Chen Miao;Yueming Cai;Wen Wu;
      Pages: 510 - 514
      Abstract: In this letter, a novel covert communication strategy that utilizes a time modulated retrodirective array (TMRDA) is proposed to enhance communication covertness. Typically, beamforming (BF) is designed via employing cuckoo search (CS), in which the sidelobes are significantly suppressed. Then, the closed-form expression of covertness constraint is derived by considering the beam characteristic of TMRDA. On this basis, the block length and transmit power are further optimized to maximize the covert throughput. Our numerical results reveal the superiority of the proposed scheme over the existing covert communication strategies.
      PubDate: MON, 20 NOV 2023 09:17:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Deep Unfolded Fractional Programming-Based Beamforming in RIS-Aided MISO
           Systems

    • Free pre-print version: Loading...

      Authors: Wenchao Xia;Yajing Jiang;Ben Zhao;Haitao Zhao;Hongbo Zhu;
      Pages: 515 - 519
      Abstract: Reconfigurable intelligent surface (RIS) is a promising solution to programmable wireless channels. However, most existing RIS phase optimization algorithms, relying on iterative processes, suffer from high latency and poor scalability. To address this issue, we propose a low-complexity scheme based on deep unfolding. Specifically, we consider a downlink MISO system aided by a RIS and aim to maximize users’ weighted sumrate (WSR). We employ Lagrangian dual transformation to decouple the original non-convex problem into two sub-problems: transmit beamforming optimization and phase shift design. Then, we introduce a block coordinate descent (BCD) method, which still relies on iterative updates and includes complex operations such as matrix inversion, leading to high computational complexity and latency. To achieve fast solutions, we further propose to unfold the BCD method’s iterative process into layers of an interpretable neural network (NN) with a few trainable parameters. The NN is trained offline and deployed online for realtime solutions. Finally, numerical results validate the performance of the proposed scheme in terms of comparable WSR and reduced computational complexity.
      PubDate: FRI, 17 NOV 2023 09:19:30 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Secure Beamforming Design for RIS-Assisted Integrated Sensing and
           Communication Systems

    • Free pre-print version: Loading...

      Authors: Chengjun Jiang;Chensi Zhang;Chongwen Huang;Jianhua Ge;Jiguang He;Chau Yuen;
      Pages: 520 - 524
      Abstract: The communication messages carried by the detected waveforms in integrated sensing and communication (ISAC) will be at risk of being eavesdropped by the detected targets, which leads to wireless security challenges. In this letter, the physical layer security (PLS) of reconfigurable intelligent surface (RIS)-assisted ISAC systems is investigated. Specifically, after introducing artificial noise, we formulate a joint active and passive beamforming optimization problem that maximizes the multi-user sum secrecy rate. Given that the nonconvex nature of the optimization problem exists, it becomes necessary to convert it into two convex sub-problems utilizing successive convex approximation and alternating optimization. This transformation incorporates the utilization of Taylor expansion and semidefinite relaxation. Numerical simulations verify the validity of the proposed algorithm for guaranteeing security.
      PubDate: MON, 20 NOV 2023 09:17:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Practical Denoising Autoencoder for CSI Feedback Without Clean Target in
           Massive MIMO Networks

    • Free pre-print version: Loading...

      Authors: Anseok Lee;Hanjun Park;Yongjin Kwon;Heesoo Lee;Song Chong;
      Pages: 525 - 529
      Abstract: In this letter, we present a novel approach for denoising channel state information (CSI) feedback in massive multiple-input multiple-output (MIMO) cellular networks. Our method utilizes Deep Learning (DL) techniques to compress and remove noise from measured CSI. Traditional DL-based denoising requires pairs of noisy input and corresponding clean targets, which are impractical to obtain in real-world wireless networks. To address this challenge, we propose a training method of denoising autoencoder using pairs of noisy CSIs and practical data acquisition strategies. Extensive evaluations demonstrate the superior reconstruction performance of our method compared to a vanilla autoencoder and legacy codebook-based CSI feedback.
      PubDate: TUE, 21 NOV 2023 09:17:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Average AoI-Minimal Trajectory Design for UAV-Assisted IoT Data Collection
           System: A Safe-TD3 Approach

    • Free pre-print version: Loading...

      Authors: Hongguang Sun;Yi Zhou;Jinchen Tang;Zhangsai Kang;Xijun Wang;Tony Q. S. Quek;
      Pages: 530 - 534
      Abstract: This letter investigates an unmanned aerial vehicle (UAV)-assisted data collection strategy where the UAV trajectory is optimally designed to collect status update from several Internet of Things (IoT) nodes, so as to minimize the average Age of Information (AoI). We consider a practical three-dimensional (3D) urban environment, and design the UAV’s trajectory by considering the data collection, flight, and energy constraints. Motivated by the critical safety requirements for the UAV, i.e., the energy constraint during the data collection, we exploit the twin delayed deep deterministic policy gradient (TD3) approach by enforcing the safety constraint throughout the training, and propose a Safe-TD3 based trajectory design for average AoI minimization. By evaluating the long-term safety constraint via the integrated cost network, we illustrate the superiority of the proposed Safe-TD3 based trajectory design algorithm over the benchmarks in reducing the safety constraint violations during the training process while achieving a lower average AoI.
      PubDate: TUE, 28 NOV 2023 09:21:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Physical Layer Secret Key Generation With the Aid of Spatially Correlated
           Active RIS

    • Free pre-print version: Loading...

      Authors: Vahid Shahiri;Hamid Behroozi;
      Pages: 535 - 539
      Abstract: Recently, there has been a growing interest in utilizing reconfigurable intelligent surfaces (RIS) for physical layer key generation (PLKG) due to their ability to intelligently configure the wireless medium. However, to the best of our knowledge, no study has explored the potential of active RIS (ARIS) in aiding PLKG. Motivated by this gap, this letter investigates the application of ARIS in PLKG. Furthermore, most existing RIS-aided PLKG techniques are based on the idealistic assumption of independent and identically distributed (i.i.d.) fading model at the RIS. Accordingly, we further consider the intrinsic correlated fading among the RIS elements. We derive the secret key rate (SKR) of the ARIS-aided PLKG and propose a sequential convex approximation (SCA) based optimization method to jointly optimize the phase and gain of the ARIS to reach maximum SKR. Additionally, we compare the performance of passive RIS (PRIS) aided PLKG with ARIS-aided PLKG. We show that with an equal total power budget, ARIS leads to significantly higher SKR, thereby offering promisingly high energy efficiency (EE) compared to PRIS.
      PubDate: TUE, 21 NOV 2023 09:17:23 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • On the Limits of Single Anchor Localization: Near-Field Versus Far-Field

    • Free pre-print version: Loading...

      Authors: Don-Roberts Emenonye;Harpreet S. Dhillon;R. Michael Buehrer;
      Pages: 540 - 544
      Abstract: It is well known that a single anchor can be used to determine the position and orientation of an agent communicating with it. However, it is not clear what information about the anchor or the agent is necessary to perform this localization, especially when the agent is in the near-field of the anchor. Hence, in this letter, to investigate the limits of localizing an agent with some uncertainty in the anchor location, we consider a wireless link consisting of source and destination nodes. More specifically, we present a Fisher information theoretical investigation of the possibility of estimating different combinations of the source and destination’s position and orientation from the signal received at the destination. To present a comprehensive study, we perform this Fisher information theoretic investigation under both the near and far field propagation models. One of the key insights is that while the source or destination’s 3D orientation can be jointly estimated with the source or destination’s 3D position in the near-field propagation regime, only the source or destination’s 2D orientation can be jointly estimated with the source or destination’s 2D position in the far-field propagation regime. Also, a simulation of the FIM indicates that in the near-field, we can estimate the source’s 3D orientation angles with no beamforming, but in the far-field, we can not estimate the source’s 2D orientation angles when no beamforming is employed.
      PubDate: WED, 22 NOV 2023 09:17:16 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • A Unified Method for Asymptotic Outage Analysis

    • Free pre-print version: Loading...

      Authors: Zheng Shi;Hong Wang;Yaru Fu;Hongjiang Lei;Mohamed-Slim Alouini;
      Pages: 545 - 549
      Abstract: This letter develops a unified method to perform the asymptotic analysis of the outage probability for a general wireless communication system. On the basis of the asymptotic results, the diversity order and the modulation and coding gain are derived in closed-form together with some special mathematical properties. Moreover, this letter reveals the scaling law of the modulation and coding gain with respect to the diversity order that provides more useful insights. The small deviation theory is then applied to obtain the asymptotic outage expression at low transmission rate, with which the tradeoff between the energy efficiency and the reliability can be examined. Finally, Monte Carlo simulations are used to corroborate our theoretical analysis.
      PubDate: WED, 22 NOV 2023 09:17:16 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Satellite Clustering for Non-Terrestrial Networks: Orbital
           Configuration-Dependent Outage Analysis

    • Free pre-print version: Loading...

      Authors: Dong-Hyun Jung;Joon-Gyu Ryu;Junil Choi;
      Pages: 550 - 554
      Abstract: This letter considers a downlink satellite communication system where a satellite cluster, i.e., a satellite swarm consisting of one leader and multiple follower satellites, serves a ground terminal. The satellites in the cluster form either a linear or circular formation moving in a group and cooperatively sending their signals by maximum ratio transmission precoding. We first conduct a coordinate transformation to effectively capture the relative positions of satellites in the cluster. Next, we derive an exact expression for the orbital configuration-dependent outage probability under the Nakagami fading by using the distribution of the sum of independent Gamma random variables. In addition, we obtain a simpler approximated expression for the outage probability with the help of second-order moment-matching. We also analyze asymptotic behavior in the high signal-to-noise ratio regime and the diversity order of the outage performance. Finally, we verify the analytical results through Monte Carlo simulations. Our analytical results provide the performance of satellite cluster-based communication systems based on specific orbital configurations, which can be used to design reliable satellite clusters in terms of cluster size, formation, and orbits.
      PubDate: THU, 23 NOV 2023 09:16:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • How to Extend 3-D GBSM to RIS Cascade Channel With Non-Ideal Phase
           Modulation'

    • Free pre-print version: Loading...

      Authors: Huiwen Gong;Jianhua Zhang;Yuxiang Zhang;Zhengfu Zhou;Guangyi Liu;
      Pages: 555 - 559
      Abstract: Reconfigurable intelligent surface (RIS) is envisioned as a promising technology for next-generation wireless communications. Its deployment introduces a RIS cascade link between the transmitter (Tx) and receiver (Rx), which makes its channel model significantly different from the Tx-Rx direct link. In this letter, a RIS cascade channel modeling method based on a 3D geometry-based stochastic model (GBSM) is proposed. The model follows a 3GPP standardized modeling framework and extends the traditional Tx-Rx channel to Tx-RIS-Rx cascade channel. In the modeling process, we consider the angle-dependent characteristics of RIS reflection coefficients caused by the boundary condition. This is referred to as non-ideal phase modulation in this letter. The differences between the proposed cascade channel model and the channel model with ideal phase modulation are investigated. The simulation results show that the proposed model can better reflect the dependence of RIS on angle and polarization.
      PubDate: TUE, 28 NOV 2023 09:21:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • On the Performance of IRS-Aided NOMA in Interference-Limited Networks

    • Free pre-print version: Loading...

      Authors: Salah Almaghthawi;Emad Alsusa;Arafat Al-Dweik;
      Pages: 560 - 564
      Abstract: This letter investigates the performance of intelligent reflecting surface (IRS) aided downlink power-domain non-orthogonal multiple access (NOMA) in Nakagami- ${m}$ fading channels with cochannel interference (CCI). Using the Gamma approximation, we derive closed-form expressions for the ergodic capacity and outage probability, while taking CCI into account. The analytical results, validated through Monte Carlo simulation, show that IRS-aided NOMA is superior to the IRS-OMA counterpart, and that the Gamma distribution closely approximates the cascaded Nakagami- ${m}$ distribution. The results are presented for various number of users and reflecting elements.
      PubDate: MON, 27 NOV 2023 09:18:35 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Low-Complexity Resource Allocation for Uplink RSMA in Future 6G Wireless
           Networks

    • Free pre-print version: Loading...

      Authors: Jiewen Hu;Gang Liu;Zheng Ma;Ming Xiao;Pingzhi Fan;
      Pages: 565 - 569
      Abstract: Uplink rate-splitting multiple access (RSMA) requires optimization of decoding order and power allocation, while decoding order is a discrete variable, and it is very complex to find the optimal decoding order if the number of users is large enough. This letter proposes a low-complexity user pairing-based resource allocation algorithm with the objective of minimizing the maximum latency. Closed-form expressions for power and bandwidth allocation for a given latency are first derived. Then a bisection method is used to determine the minimum latency and optimal resource allocation. Finally, the proposed algorithm is compared with unpaired RSMA using an exhaustive method to obtain the optimal decoding order, unpaired RSMA using a suboptimal decoding order, paired non-orthogonal multiple access (NOMA) and unpaired NOMA. The results show that our proposed algorithm outperforms NOMA and achieves similar performance to unpaired RSMA. In addition, the complexity of the proposed algorithm is significantly reduced.
      PubDate: TUE, 28 NOV 2023 09:21:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Statistical CSI-Based Beamforming for RIS-Aided Multiuser MISO Systems via
           Deep Reinforcement Learning

    • Free pre-print version: Loading...

      Authors: Mahdi Eskandari;Huiling Zhu;Arman Shojaeifard;Jiangzhou Wang;
      Pages: 570 - 574
      Abstract: This letter presents a novel joint beamforming algorithm for reconfigurable intelligent surfaces (RIS) in multiuser multiple-input single-output (MISO) wireless communications. At first, by utilizing statistical channel state information (CSI) instead of instantaneous CSI, we significantly reduce channel estimation overhead. Then, the optimization of beamforming weights is accomplished using the proximal policy optimization (PPO) algorithm, a well-established actor-critic-based reinforcement learning (RL) approach. The impact of system parameters on user sum rate is also analyzed through simulations. The results show the PPO algorithm outperforms the existing methods by combining beamforming techniques with statistical CSI.
      PubDate: TUE, 28 NOV 2023 09:21:22 -04
      Issue No: Vol. 13, No. 2 (2023)
       
  • Joint Parallel Tabu Search Algorithm-Based Look-Up Table Design and Deep
           Learning-Based Signal Detection for OFDM-AIM

    • Free pre-print version: Loading...

      Authors: Mahmut Yıldırım;
      Pages: 575 - 579
      Abstract: This letter first proposes a parallel Tabu Search (PTS) algorithm-based look-up table for orthogonal frequency division multiplexing with all index modulation (OFDM-AIM) called PTS-AIM. In the conventional OFDM-AIM (referred to as AIM in this letter), each subcarrier within a subblock is mapped to the same quadrature amplitude modulation (QAM) constellation points, while in the PTS-AIM, the PTS algorithm searches the optimum constellation point for each subcarrier to improve the bit error rate (BER) performance. Secondly, a deep learning (DL)-based signal detector termed as DeepAIM is proposed, which combines long short-term memory (LSTM) algorithm and deep neural network (DNN). Finally, a novel architecture, PTS-DeepAIM, is designed, where PTS-AIM and DeepAIM schemes are considered together. The simulation results show that the proposed PTS-DeepAIM outperforms AIM in BER performance and computation time, thanks to the benefit of the unified PTS-based look-up table design and DL-based signal detection architecture.
      PubDate: THU, 14 DEC 2023 09:17:55 -04
      Issue No: Vol. 13, No. 2 (2023)
       
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 44.220.62.183
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-
JournalTOCs
 
 
  Subjects -> COMMUNICATIONS (Total: 518 journals)
    - COMMUNICATIONS (446 journals)
    - DIGITAL AND WIRELESS COMMUNICATION (31 journals)
    - HUMAN COMMUNICATION (19 journals)
    - MEETINGS AND CONGRESSES (7 journals)
    - RADIO, TELEVISION AND CABLE (15 journals)

DIGITAL AND WIRELESS COMMUNICATION (31 journals)

Showing 1 - 31 of 31 Journals sorted alphabetically
Ada : A Journal of Gender, New Media, and Technology     Open Access   (Followers: 22)
Advances in Image and Video Processing     Open Access   (Followers: 24)
Communications and Network     Open Access   (Followers: 13)
E-Health Telecommunication Systems and Networks     Open Access   (Followers: 3)
EURASIP Journal on Wireless Communications and Networking     Open Access   (Followers: 14)
Future Internet     Open Access   (Followers: 87)
Granular Computing     Hybrid Journal  
IEEE Transactions on Wireless Communications     Hybrid Journal   (Followers: 26)
IEEE Wireless Communications Letters     Hybrid Journal   (Followers: 42)
IET Wireless Sensor Systems     Open Access   (Followers: 18)
International Journal of Communications, Network and System Sciences     Open Access   (Followers: 9)
International Journal of Digital Earth     Hybrid Journal   (Followers: 15)
International Journal of Embedded and Real-Time Communication Systems     Full-text available via subscription   (Followers: 6)
International Journal of Interactive Communication Systems and Technologies     Full-text available via subscription   (Followers: 2)
International Journal of Machine Intelligence and Sensory Signal Processing     Hybrid Journal   (Followers: 3)
International Journal of Mobile Computing and Multimedia Communications     Full-text available via subscription   (Followers: 2)
International Journal of Satellite Communications and Networking     Hybrid Journal   (Followers: 39)
International Journal of Wireless and Mobile Computing     Hybrid Journal   (Followers: 8)
International Journal of Wireless Networks and Broadband Technologies     Full-text available via subscription   (Followers: 2)
International Journals Digital Communication and Analog Signals     Full-text available via subscription   (Followers: 2)
Journal of Digital Information     Open Access   (Followers: 181)
Journal of Interconnection Networks     Hybrid Journal   (Followers: 1)
Journal of the Southern Association for Information Systems     Open Access   (Followers: 2)
Mobile Media & Communication     Hybrid Journal   (Followers: 10)
Nano Communication Networks     Hybrid Journal   (Followers: 5)
Psychology of Popular Media Culture     Full-text available via subscription   (Followers: 1)
Signal, Image and Video Processing     Hybrid Journal   (Followers: 11)
Ukrainian Information Space     Open Access  
Vehicular Communications     Full-text available via subscription   (Followers: 4)
Vista     Open Access   (Followers: 4)
Wireless Personal Communications     Hybrid Journal   (Followers: 6)
Similar Journals
Similar Journals
HOME > Browse the 73 Subjects covered by JournalTOCs  
SubjectTotal Journals
 
 
JournalTOCs
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


Your IP address: 44.220.62.183
 
Home (Search)
API
About JournalTOCs
News (blog, publications)
JournalTOCs on Twitter   JournalTOCs on Facebook

JournalTOCs © 2009-