{"title":"Pilot-Based Codebook Artificial Noise for Enhanced Physical Layer Security in MA-Enabled MIMO Systems","authors":"Yebo Gu;Tao Zhao;Hongrou Su;Tao Shen;Jian Song","doi":"10.1109/LCOMM.2025.3580959","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3580959","url":null,"abstract":"This letter introduces pilot-based codebook artificial noise (PCAN) into movable antenna (MA)-enabled MIMO communication systems. It investigates the problem of optimizing secrecy capacity (SC) through the joint optimization of transmit covariance matrices and antenna positions. The sequential convex programming (SCP) method is employed to linearize the non-convex parts of the optimization problem, and an alternating optimization (AO) algorithm is utilized to iteratively solve for both the transmit covariance matrices and antenna positions. Simulation results demonstrate a significant improvement in SC. The proposed approach provides a robust solution for enhancing physical layer security in wireless communication systems, offering practical insights for future secure communications.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1938-1942"},"PeriodicalIF":4.4,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831837","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}
Tingyu Xie;Guoshun Nan;Qimei Cui;Gang Deng;Haitao Du;Xiaofeng Tao
{"title":"Joint Optimization of Active and Passive Beamforming for RIS-Assisted Secure Communication Under Multiple Eavesdroppers","authors":"Tingyu Xie;Guoshun Nan;Qimei Cui;Gang Deng;Haitao Du;Xiaofeng Tao","doi":"10.1109/LCOMM.2025.3581052","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3581052","url":null,"abstract":"Reconfigurable Intelligent Surface (RIS) facilitates physical-layer secure communications (PSC) by smartly controlling signal features such as phase and amplitude. Previous work shows that an illegal eavesdropper can sharply reduce the capacity for RIS-assisted PSC, while multiple eavesdroppers in the communication system, a more practical and challenging setting in the real world, is still largely underexplored. To this end, we present MuEaRIS, a novel approach that aims to maximize legitimate secure communication rates while minimizing the rate of each illegal eavesdropper for RIS-assisted PSC. Specifically, we jointly optimize Alice’s active beamforming and RIS’s passive beamforming using a novel method that explores alternating optimization and quadratic transformation. Numerical analysis shows that the proposed MuEaRIS is effective for RIS-assisted PSC in multi eavesdropper scenarios, while also outperforming existing methods in single eavesdropper settings, demonstrating broader applicability.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1943-1947"},"PeriodicalIF":4.4,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831841","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":"Deep Learning-Based Sparse Recovery and Dictionary Matching for Multipath Time Delay Estimation","authors":"Yipeng Li;Keke Hu;Manyu Xue;Yuan Shen","doi":"10.1109/LCOMM.2025.3580559","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3580559","url":null,"abstract":"Wireless channel responses contain rich multipath information, but accurately extracting this information remains challenging in complex indoor environments. In this letter, we propose a deep learning-based sparse recovery method for super-resolution multipath time delay estimation and dictionary mismatch mitigation in sparse modeling. The proposed DenoisingCNN framework recovers the sparse delay spectrum from the channel response with highly overlapping multipath components with three specialized modules to address dictionary mismatch. Numerical results demonstrate that the proposed method outperforms state-of-the-art approaches in the estimation of both the number and delays of the multipath components, offering robustness and strong generalization capabilities.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1933-1937"},"PeriodicalIF":4.4,"publicationDate":"2025-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831839","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}
Xiaoqi Zhang;Xu Ma;Haijun Zhang;Yuzheng Ren;Difei Cao;Victor C. M. Leung
{"title":"Physical Layer Security Enhancement for Beyond Diagonal RIS-Aided MIMO Communications","authors":"Xiaoqi Zhang;Xu Ma;Haijun Zhang;Yuzheng Ren;Difei Cao;Victor C. M. Leung","doi":"10.1109/LCOMM.2025.3579860","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3579860","url":null,"abstract":"Beyond diagonal reconfigurable intelligent surface (BD-RIS) has demonstrated remarkable performance over conventional RIS through its unique flexible signal manipulation capability. This letter investigates physical layer security enhancement in a multiple-input multiple-output (MIMO) system aided by BD-RIS under eavesdropping channel. To achieve the maximal secrecy rate, we co-optimize the transmit covariance matrix and the BD-RIS unitary matrix. First, the projected gradient method refines the transmit beamforming to adhere to power constraints. Second, we propose an adaptive Riemannian conjugate gradient algorithm that incorporates low-order Taylor series expansions for geodesic approximation and hybrid conjugate parameters for co-optimization, ensuring the unitary constraint of the BD-RIS matrix. Numerical results indicate that the proposed algorithm significantly outperforms conventional RIS scheme and the benchmark schemes.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1919-1923"},"PeriodicalIF":4.4,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831877","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}
Rong Zeng;Zengxian Lin;Zaichen Zhang;Na Ying;Afeng Yang
{"title":"Spectrum Efficiency and Link Reliability Enhancement Algorithm in IRS-Assisted OTFS Systems for Vehicular Networks","authors":"Rong Zeng;Zengxian Lin;Zaichen Zhang;Na Ying;Afeng Yang","doi":"10.1109/LCOMM.2025.3579935","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3579935","url":null,"abstract":"Orthogonal Time Frequency Space (OTFS) modulation offers a promising solution for Vehicle To Everything (V2X) scenarios. In this letter, we present an algorithm that reduces pilot overhead and improves link reliability, which enhances spectral efficiency in IRS (Intelligent Reflecting Surface)-assisted OTFS systems. The method projects received signals onto orthogonal subspaces and performs channel matching within each subspace to minimize pilot overhead. And we utilize the Grey Wolf Optimization (GWO) Algorithm to calculate the channel matching parameters. Additionally, an adaptive pilot overhead reduction(APOR) scheme is presented to further enhance spectral efficiency. Simulation results verify that the proposed methods significantly improve system reliability and throughput rate.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1924-1927"},"PeriodicalIF":4.4,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831878","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":"Semantics-Aware Updates From Remote Energy Harvesting Devices to Interconnected LEO Satellites","authors":"Erfan Delfani;Nikolaos Pappas","doi":"10.1109/LCOMM.2025.3580155","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3580155","url":null,"abstract":"Providing timely and informative data in integrated terrestrial and non-terrestrial networks is critical as data volume grows while the resources available on devices remain limited. To address this, we adopt a semantics-aware approach to optimize the Version Age of Information (VAoI) in a status update system in which a remote Energy Harvesting (EH) Internet of Things (IoT) device samples data and transmits it to a network of interconnected Low Earth Orbit (LEO) satellites for dissemination and utilization. The optimal update policy is derived through stochastic modeling and optimization of the VAoI across the network. The results indicate that this policy reduces the frequency of updates by skipping stale or irrelevant data, significantly improving energy efficiency.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1928-1932"},"PeriodicalIF":4.4,"publicationDate":"2025-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831875","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":"Optimizing Smart Helper Placement for Enhanced Cache Efficiency in F-RANs","authors":"Hesameddin Mokhtarzadeh;Mohammed Saif;Md. Jahangir Hossain;Julian Cheng","doi":"10.1109/LCOMM.2025.3579670","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3579670","url":null,"abstract":"Smart helpers (SHs) have been proposed to improve content delivery delays and alleviate high fronthaul loads in fog radio access networks (F-RANs). They offer an alternative to deploying additional enhanced remote radio heads (RRHs), which are often infeasible due to site constraints. The optimal placement of SHs can significantly increase the number of users they serve which leads to enhanced cache efficiency and improved content delivery delay. In this letter, we optimize SH placement within an F-RAN to maximize the cache hit rate and further reduce the content delivery latency. We model the SH cache hit rate as a function of outage probability and user density distribution. We develop a function to estimate user density distribution leveraging the radial basis functions (RBFs) method and optimize SH placement utilizing the particle swarm optimization (PSO) algorithm. Our numerical results confirm the effectiveness of the proposed approach in maximizing the SH cache hit rate, thereby improving delivery delays and fronthaul loads of the network.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1909-1913"},"PeriodicalIF":4.4,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831671","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":"Attitude-Based User Terminal Beam Pointing Using Downlink Data Bursts From Broadband Satellites","authors":"Zilan Yu;Xi Chen;Liuguo Yin;Linling Kuang","doi":"10.1109/LCOMM.2025.3579717","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3579717","url":null,"abstract":"In satellite communications, beam pointing is fundamental for the user terminal to perform stable communications with passing satellites. The traditional energy-based user terminal beam pointing method tracks the energy of received signals, which requires the received signal to have a good enough signal-to-noise ratio (SNR) to search for the energy peak. In this work, an antenna attitude-based beam pointing method using downlink data bursts from broadband satellites is proposed. The proposed method consists of two stages: in the acquisition stage, the user terminal achieves rough beam alignment using a 9-axis inertial measurement unit (IMU) as the conventional method; and in the tracking stage, super-resolution time difference of arrival (TDOA) measurements are obtained from a phased array antenna with multiple subarrays by receiving data bursts from the passing satellite. The TDOA measurements are fused with the triaxial gyroscope and triaxial magnetometer outputs through the proposed factor graph optimization-based fine attitude estimation algorithm to achieve fine attitude estimation results, from which the optimal beam pointing direction is derived. The simulation results show that the proposed method achieves 0.2° beam pointing estimation precision when a 1 ms, 100 MHz 5G non-terrestrial network (NTN) downlink orthogonal frequency division multiplexing (OFDM) signal is available per second.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1914-1918"},"PeriodicalIF":4.4,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831880","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":"Satellite-Based Emitter Geolocation Using Matched Location Processing","authors":"Caiyong Hao;Xianrong Wan;Feng He;Jianxin Yi","doi":"10.1109/LCOMM.2025.3579652","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3579652","url":null,"abstract":"Radio emitter geolocation via satellite-based systems is crucial for global spectrum monitoring and interference mitigation. This letter proposes matched location processing (MLP), a novel technique that achieves precise geolocation through coherent phase measurements from multiple satellites. MLP determines emitter locations by maximizing the correlation between received signals and location-specific modeled signals derived from radio propagation analysis. While extending spatial beamforming principles, MLP incorporates normalized phase correlation processing to surpass existing direct position determination (DPD) methods in both accuracy and computational efficiency. Simulation results demonstrate robust performance in extremely low signal-to-noise ratio (SNR) environments, achieving geolocation accuracy within 10 km at −30 dB SNR. Furthermore, the method’s location-selective phase matching capability enables effective spatial discrimination of multiple co-frequency emitters.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1904-1908"},"PeriodicalIF":4.4,"publicationDate":"2025-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831706","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":"New Constructions of Z-Complementary Code Sets Based on Generalized Column Orthogonal Matrices","authors":"Fanfei Meng;Kai Liu;Jiapeng Li;Xinyu Shao","doi":"10.1109/LCOMM.2025.3578954","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3578954","url":null,"abstract":"Z-complementary code sets (ZCCSs) are widely employed in multi-carrier spread spectrum and MIMO communication systems. This study introduces the concept and construction of generalized column orthogonal (GCO) matrices to develop new classes of Z-paraunitary (ZPU) matrices. Utilizing the equivalence between ZCCSs and ZPU matrices, novel polyphase ZCCSs are constructed. The flexible sizing of GCO matrices allows for a wide range of parameter configurations. The proposed method enables the derivation of optimal ZCCS parameters that are unattainable in existing literature. Furthermore, by designing GCO matrices whose column vectors exhibit low peak-to-mean envelope power ratio (PMEPR), ZCCSs with column sequence PMEPR no greater than 2 are achieved. This work expands the repertoire of code options for various communication scenarios.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 8","pages":"1899-1903"},"PeriodicalIF":4.4,"publicationDate":"2025-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144831707","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}