{"title":"A Lightweight RL-Driven Deep Unfolding Network for Robust WMMSE Precoding","authors":"Kexuan Wang;An Liu","doi":"10.1109/LCOMM.2025.3600648","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3600648","url":null,"abstract":"Weighted Minimum Mean Square Error (WMMSE) precoding can achieve near-optimal weighted sum rate (WSR) in MU-MIMO-OFDM systems, but it suffers from high computational complexity and severe dependence on accurate channel state information (CSI). This letter proposes a lightweight reinforcement learning (RL)-driven deep unfolding (DU) network (RLDDU-Net) to overcome these limitations. Specifically, its DU module maps a wideband stochastic WMMSE algorithm, which maximizes the ergodic WSR under imperfect CSI, into a deep-learning framework. Approximation techniques exploiting beam-domain sparsity and subcarrier correlation are also adopted to significantly reduce complexity and accelerate convergence. The RL module dynamically generates compensation matrices to mitigate approximation errors and adjusts DU network depth online, thereby enhancing both flexibility and performance. Simulation results demonstrate that RLDDU-Net outperforms existing baselines in terms of ergodic WSR, computational efficiency, and convergence speed under imperfect CSI.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 10","pages":"2471-2475"},"PeriodicalIF":4.4,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255879","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hang Zhu;Xuguang Xu;Lixun Han;Wei Song;Ming Tan;Xiaojun Zou
{"title":"A Symbol Timing Estimation Method With FRI Sampling for RRC Shaped Communication Signals","authors":"Hang Zhu;Xuguang Xu;Lixun Han;Wei Song;Ming Tan;Xiaojun Zou","doi":"10.1109/LCOMM.2025.3599503","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3599503","url":null,"abstract":"This letter proposes a symbol timing estimator for root-raised cosine shaped digital communication signals under finite-rate-of-innovation sampling. By incorporating symbol period prior information into the traditional model, the number of unknown parameters is further reduced. The proposed method processes the signal via spectral truncation with the width of half the number of symbols and eliminating the effect of unknown symbols through statistical analysis. Timing estimation is finally achieved by detecting inter-symbol interference-free points. Simulations demonstrate accurate performance at both oversampling rates above and below 1.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 10","pages":"2451-2455"},"PeriodicalIF":4.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Decoding-Aided Channel Estimation Based on the GC-LDPC Codes in Time-Varying MIMO Systems","authors":"Hongmei Kang;Lin Zhao;Ming Jiang;Chunming Zhao","doi":"10.1109/LCOMM.2025.3600544","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3600544","url":null,"abstract":"Massive multiple-input multiple-output (MIMO) has been widely adopted in next-generation wireless systems to enhance spectral efficiency and reliability. However, channel aging poses a significant challenge, leading to the outdated channel state information and degraded system performance. To address this issue, we propose a decoding-aided Kalman filter channel tracking algorithm based on the globally-coupled low-density parity-check (GC-LDPC) codes. The proposed approach leverages locally decoded symbols to optimize channel estimation and employs global decoding to further reduce the error floor. Additionally, protograph-based extrinsic information transfer analysis and the error minimization progressive edge-growth algorithm are utilized to optimize the compatible GC-LDPC codes. Simulation results demonstrate that the proposed algorithm significantly improves channel tracking performance in time-varying MIMO systems.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 10","pages":"2466-2470"},"PeriodicalIF":4.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"SKR Analysis of One- and Two-Way CV-QKD MIMO FSO Communication System","authors":"Sushil Kumar;Soumya P. Dash","doi":"10.1109/LCOMM.2025.3600331","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3600331","url":null,"abstract":"We present novel one-way and two-way continuous-variable quantum key distribution frameworks integrating multiple-input multiple-output (MIMO) and free-space optical systems to enhance secret key rates (SKRs) and extend transmission distance between the legitimate transceiver pair. Our models are subjected to an eavesdropper employing Gaussian collective attacks, and the receiver using homodyne detection for secret key reception. Novel expressions for the SKRs for both frameworks are computed, and asymptotic results demonstrate that both the SKR gains from employing MIMO and the two-way protocol are proportional to squared-root of the MIMO channels.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 10","pages":"2456-2460"},"PeriodicalIF":4.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Capacity Lower Bound for Double-Sided Correlated Extremely Large-Scale Array Systems","authors":"Wendi Zhang;Zhuxian Lian;Yajun Wang;Zhangfeng Ma;Yinjie Su;Bibo Zhang;Zhibin Xie","doi":"10.1109/LCOMM.2025.3600538","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3600538","url":null,"abstract":"To explore the impact of spatial non-stationarity on the performance of extra-large scale multiple-input multiple-output (XL-MIMO) communication systems, this letter proposes a new double-sided correlated channel model based on the visibility region (VR). Based on the proposed model, the corresponding downlink ergodic capacity is investigated. We find that when the VR size remains constant, the ergodic capacity decreases as the number of transmit antennas increases. Due to the closed-form expressions for ergodic capacity being related to Laguerre polynomials, which requires numerical integration for evaluation, the closed-form lower bounds on ergodic capacity are investigated. In XL-MIMO systems, the number of transmit antennas is significantly greater than the rank of the XL-MIMO channel, and we use the theorem of principal minor determinant expansion and Binet-Cauchy theorem to obtain the closed-form lower bound on the ergodic capacity. Compared to the Monte-Carlo simulation results, the proposed lower bound is tight and suitable for application in XL-MIMO communication systems.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 10","pages":"2461-2465"},"PeriodicalIF":4.4,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Detection of Unknown RF Signals Using Rydberg-Atom Quantum MIMO Receivers","authors":"Saman Atapattu;Nathan Ross;Harini Hapuarachchi","doi":"10.1109/LCOMM.2025.3599481","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3599481","url":null,"abstract":"Rydberg-atom quantum receivers (RAQRs) enable ultra-sensitive radio frequency (RF) detection by transducing incident fields into the optical domain with minimal quantum noise. This letter addresses the unexplored problem of detecting unknown RF signal presence under noise by formulating it as a binary hypothesis test for MIMO RAQRs with nonlinear magnitude-only measurements. We derive likelihood ratio tests (LRTs) under varying channel and signal knowledge, and propose a non-coherent constant false alarm rate (CFAR) energy detector for fully unknown scenarios. We analyze the role of reference signals, showing that excessive reference power can impair detection. Simulations demonstrate superior performance of the proposed RAQR over RF receiver.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 10","pages":"2446-2450"},"PeriodicalIF":4.4,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145255923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"RIS-Based Optimized Dual Attack: Jamming and Eavesdropping With Partial CSI","authors":"Yinuo Hao;Jiale Bai;Honghao Zheng;Liang Jin;Shuaifang Xiao","doi":"10.1109/LCOMM.2025.3591004","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3591004","url":null,"abstract":"This letter proposes a novel Reconfigurable Intelligent Surface (RIS)-based optimized dual attack (RIS-ODA) strategy for eavesdropping and jamming in wireless communication systems. The RIS-ODA leverages partial Channel State Information (CSI) to simultaneously enhance eavesdropping rate and degrade the legitimate receiver’s communication rate. The attack strategy is formulated as a dual-objective optimization problem, which is solved using triangle inequality and Bernstein-Type Inequality (BTI) to handle probability measure constraints. Simulation results demonstrate that the proposed method effectively enhances eavesdropping rate and suppresses Bob’s communication rate without requiring perfect CSI or additional power, achieving a superior balance between attack performance and practical implementation feasibility.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 9","pages":"2198-2202"},"PeriodicalIF":4.4,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhancing 5G Downlink Positioning Security: Embedding a Novel Authentication Scheme Into Empty PRS Resource Elements","authors":"Thodoris Spanos;Nikolaos Papageorgiou;Vassilis Paliouras","doi":"10.1109/LCOMM.2025.3590481","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3590481","url":null,"abstract":"As wireless communication expands, there is a growing need for precise and secure location-based services. This work presents a novel authentication scheme designed to enhance security in 5G downlink positioning using the positioning reference signal (PRS). The proposed method embeds a hash-based message authentication code (HMAC) of the PRS into the empty resource elements (REs) of its comb-based structure, along with the original PRS sequence. Furthermore, a novel authentication similarity threshold is introduced, enabling the HMAC authentication process to operate under lower SNR conditions. In addition, the proposed method in the presence of channel estimation, synchronization and carrier frequency offset errors is quantified, reporting the percentage of erroneous bits in each extracted HMAC sequence. The robustness of the proposed threshold mechanism is highlighted, demonstrating its ability to tolerate bit errors caused by impairments of the physical layer. Simulations reveal that occupation of these REs does not affect position estimation.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 9","pages":"2188-2192"},"PeriodicalIF":4.4,"publicationDate":"2025-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11084864","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145073303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}