Pub Date : 2025-09-30DOI: 10.1109/JSAC.2025.3616075
Yu Chen;Bowen Xu;Shijie Li;Qimei Cui;Xiaofeng Tao
The fluid antenna system (FAS) is a reconfigurable antenna technology that enhances wireless communications by adapting to time-varying channel conditions. However, existing FAS research focuses on physical-layer performance, neglecting link-layer quality-of-service (QoS) guarantees like latency/delay. This paper develops a cross-layer model to investigate the low-latency performance of a slow fluid antenna multiple access ($s$ -FAMA) system in a multi-user downlink scenario, employing the effective capacity (EC) framework. We first derive approximate expressions for the total EC in a multi-user $s$ -FAMA system under both complex and simplified channel models. To validate them, we propose a quasi-Monte Carlo (QMC) method to compute multidimensional integrals, overcoming the limitations of conventional numerical methods and solving a class of multidimensional integral numerical simulation problems for large-scale FAMA systems. Then, we formulate an optimization problem to maximize the total EC while satisfying the total power constraint and each user’s minimum EC requirement. To jointly optimize port selection and power allocation, an iterative algorithm based on alternating optimization (AO) and quadratic transform (QT) is proposed to solve the non-convex problem. Simulation results validate our approximations and show that our joint port selection and power allocation scheme outperforms the conventional baseline algorithms, confirming our proposed algorithm’s effectiveness and FAS’s superiority in ensuring the QoS in wireless communications.
{"title":"Analysis and Optimization for Low-Latency Communications in Slow Fluid Antenna Multiple Access Systems","authors":"Yu Chen;Bowen Xu;Shijie Li;Qimei Cui;Xiaofeng Tao","doi":"10.1109/JSAC.2025.3616075","DOIUrl":"10.1109/JSAC.2025.3616075","url":null,"abstract":"The fluid antenna system (FAS) is a reconfigurable antenna technology that enhances wireless communications by adapting to time-varying channel conditions. However, existing FAS research focuses on physical-layer performance, neglecting link-layer quality-of-service (QoS) guarantees like latency/delay. This paper develops a cross-layer model to investigate the low-latency performance of a slow fluid antenna multiple access (<inline-formula> <tex-math>$s$ </tex-math></inline-formula>-FAMA) system in a multi-user downlink scenario, employing the effective capacity (EC) framework. We first derive approximate expressions for the total EC in a multi-user <inline-formula> <tex-math>$s$ </tex-math></inline-formula>-FAMA system under both complex and simplified channel models. To validate them, we propose a quasi-Monte Carlo (QMC) method to compute multidimensional integrals, overcoming the limitations of conventional numerical methods and solving a class of multidimensional integral numerical simulation problems for large-scale FAMA systems. Then, we formulate an optimization problem to maximize the total EC while satisfying the total power constraint and each user’s minimum EC requirement. To jointly optimize port selection and power allocation, an iterative algorithm based on alternating optimization (AO) and quadratic transform (QT) is proposed to solve the non-convex problem. Simulation results validate our approximations and show that our joint port selection and power allocation scheme outperforms the conventional baseline algorithms, confirming our proposed algorithm’s effectiveness and FAS’s superiority in ensuring the QoS in wireless communications.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1290-1306"},"PeriodicalIF":17.2,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145195230","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The emerging technology of fluid antennas (FAs) offers significant opportunities for enhancing the performance of wireless communication. Hybrid antenna designs that incorporate reconfigurable antennas offer exceptional flexibility, thereby enhancing adaptability to diverse communication requirements. With their inherent reconfigurability and adaptability, hybrid antennas incorporating FAs represent a promising solution for realizing continuous-aperture array (CAPA). A CAPA is capable of flexibly and efficiently exciting surface currents, thereby generating the desired electromagnetic waves. Vortex electromagnetic waves with different orbital angular momentum (OAM) modes are spatially orthogonal, providing a novel spatial multiplexing dimension for wireless communication. To meet the demand of high-capacity communication, from the perspective of electromagnetic information theory (EIT), we investigate an OAM orthogonal transmission system based on CAPA and explore the performance limits of the system. We propose an innovative hybrid antenna that integrates FAs with fixed-position antennas (FPAs) to realize CAPA, and design the surface currents of the CAPA using Fourier basis functions. Furthermore, we explore the electromagnetic channel model and derive the upper bound of the spectrum efficiency for CAPA-based OAM orthogonal transmission. This paper establishes a theoretical foundation for applying EIT to the orthogonal transmission of vortex electromagnetic waves, offering a novel solution for achieving efficient and high-capacity communication based on CAPA integrated with FAs.
{"title":"Achieving High-Capacity OAM Communication With Fluid-Antenna-Based Continuous-Aperture Arrays","authors":"Hongyun Jin;Wenchi Cheng;Jingqing Wang;Qinghe Du;Wei Zhang","doi":"10.1109/JSAC.2025.3615195","DOIUrl":"10.1109/JSAC.2025.3615195","url":null,"abstract":"The emerging technology of fluid antennas (FAs) offers significant opportunities for enhancing the performance of wireless communication. Hybrid antenna designs that incorporate reconfigurable antennas offer exceptional flexibility, thereby enhancing adaptability to diverse communication requirements. With their inherent reconfigurability and adaptability, hybrid antennas incorporating FAs represent a promising solution for realizing continuous-aperture array (CAPA). A CAPA is capable of flexibly and efficiently exciting surface currents, thereby generating the desired electromagnetic waves. Vortex electromagnetic waves with different orbital angular momentum (OAM) modes are spatially orthogonal, providing a novel spatial multiplexing dimension for wireless communication. To meet the demand of high-capacity communication, from the perspective of electromagnetic information theory (EIT), we investigate an OAM orthogonal transmission system based on CAPA and explore the performance limits of the system. We propose an innovative hybrid antenna that integrates FAs with fixed-position antennas (FPAs) to realize CAPA, and design the surface currents of the CAPA using Fourier basis functions. Furthermore, we explore the electromagnetic channel model and derive the upper bound of the spectrum efficiency for CAPA-based OAM orthogonal transmission. This paper establishes a theoretical foundation for applying EIT to the orthogonal transmission of vortex electromagnetic waves, offering a novel solution for achieving efficient and high-capacity communication based on CAPA integrated with FAs.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1449-1463"},"PeriodicalIF":17.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188393","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1109/JSAC.2025.3615171
Yan Li;Yitao Xu;Qiaoyu Tian;Haichao Wang;Jiangchun Gu;Guofeng Wei;Guoru Ding
High Frequency (HF) communication, operating within the 3 to 30 MHz range, has been pivotal for long-distance wireless communication, especially in scenarios where infrastructure (such as satelittes or base stations) are limited or unavailable and beyond-line-of-sight. This paper investigates the potential of fluid antenna multiple access (FAMA) to enhance HF communication performance by leveraging the dynamic nature of fluid antenna systems to match the time-varying ionospheric channel. We first establish a comprehensive system model that incorporates both spatial block-correlation and ionospheric propagation characteristics. Based on this model, we derive closed-form expressions for outage probability under both high and low SNR scenarios. To address the challenges of user interference and frequency resource allocation, we propose an efficient user grouping algorithm based on K-means clustering, which considers users’ channel characteristics and spatial distribution. Furthermore, we develop a frequency selection strategy to optimize system performance while minimizing inter-group interference. Numerical simulations demonstrate that our proposed FAMA scheme significantly improves system reliability and resource utilization by reducing the outage probability under typical operating conditions.
{"title":"Fluid Antenna Multiple Access for HF Skywave Communications","authors":"Yan Li;Yitao Xu;Qiaoyu Tian;Haichao Wang;Jiangchun Gu;Guofeng Wei;Guoru Ding","doi":"10.1109/JSAC.2025.3615171","DOIUrl":"10.1109/JSAC.2025.3615171","url":null,"abstract":"High Frequency (HF) communication, operating within the 3 to 30 MHz range, has been pivotal for long-distance wireless communication, especially in scenarios where infrastructure (such as satelittes or base stations) are limited or unavailable and beyond-line-of-sight. This paper investigates the potential of fluid antenna multiple access (FAMA) to enhance HF communication performance by leveraging the dynamic nature of fluid antenna systems to match the time-varying ionospheric channel. We first establish a comprehensive system model that incorporates both spatial block-correlation and ionospheric propagation characteristics. Based on this model, we derive closed-form expressions for outage probability under both high and low SNR scenarios. To address the challenges of user interference and frequency resource allocation, we propose an efficient user grouping algorithm based on K-means clustering, which considers users’ channel characteristics and spatial distribution. Furthermore, we develop a frequency selection strategy to optimize system performance while minimizing inter-group interference. Numerical simulations demonstrate that our proposed FAMA scheme significantly improves system reliability and resource utilization by reducing the outage probability under typical operating conditions.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1144-1159"},"PeriodicalIF":17.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1109/JSAC.2025.3615576
Long Zhang;Yizhe Zhao;Halvin Yang;Guangming Liang;Jie Hu
Integrated data and energy transfer (IDET) is considered as a key enabler of 6G, as it can provide both wireless energy transfer (WET) and wireless data transfer (WDT) services towards low power devices. Thanks to the extra degree of freedom provided by fluid antenna (FA), incorporating FA into IDET systems presents a promising approach to enhance energy efficiency performance. This paper investigates a FA assisted IDET system, where the transmitter is equipped with multiple FAs and transmits wireless signals to the data receiver (DR) and the energy receiver (ER), both of which are equipped with a single traditional antenna. The switching delay and energy consumption induced by port selection are taken into account in IDET system for the first time. We aim to obtain the optimal beamforming vector and the port selection strategy at the transmitter, in order to maximize the short-term and long-term WET efficiency, respectively. The instant sub-optimal solution is obtained by alternatively optimizing the beamforming vector and port selection in each transmission frame, while a novel constrained soft actor critic (C-SAC) algorithm is proposed to find the feasible policy of port selection from the long-term perspective. Simulation results demonstrate that our scheme is able to achieve greater gain in terms of both the short-term and long-term WET efficiency compared to other benchmarks, while not degrading WDT performance.
{"title":"Energy-Efficient Port Selection and Beamforming Design for Integrated Data and Energy Transfer Assisted by Fluid Antennas","authors":"Long Zhang;Yizhe Zhao;Halvin Yang;Guangming Liang;Jie Hu","doi":"10.1109/JSAC.2025.3615576","DOIUrl":"10.1109/JSAC.2025.3615576","url":null,"abstract":"Integrated data and energy transfer (IDET) is considered as a key enabler of 6G, as it can provide both wireless energy transfer (WET) and wireless data transfer (WDT) services towards low power devices. Thanks to the extra degree of freedom provided by fluid antenna (FA), incorporating FA into IDET systems presents a promising approach to enhance energy efficiency performance. This paper investigates a FA assisted IDET system, where the transmitter is equipped with multiple FAs and transmits wireless signals to the data receiver (DR) and the energy receiver (ER), both of which are equipped with a single traditional antenna. The switching delay and energy consumption induced by port selection are taken into account in IDET system for the first time. We aim to obtain the optimal beamforming vector and the port selection strategy at the transmitter, in order to maximize the short-term and long-term WET efficiency, respectively. The instant sub-optimal solution is obtained by alternatively optimizing the beamforming vector and port selection in each transmission frame, while a novel constrained soft actor critic (C-SAC) algorithm is proposed to find the feasible policy of port selection from the long-term perspective. Simulation results demonstrate that our scheme is able to achieve greater gain in terms of both the short-term and long-term WET efficiency compared to other benchmarks, while not degrading WDT performance.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1480-1494"},"PeriodicalIF":17.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11184546","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188391","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1109/JSAC.2025.3615178
Xiao Lin;Yizhe Zhao;Halvin Yang;Jie Hu
This paper investigates a novel wireless powered communication network (WPCN) enabled by fluid antenna multiple access (FAMA). In the proposed system, a hybrid access point (HAP) equipped with multiple fixed-position antennas (FPA) delivers integrated data and energy transfer (IDET) services. Each low-power device is equipped with a single fluid antenna (FA) and utilizes the harvested energy to support its uplink communication. A block-correlation fading channel model is adopted to analyze the outage probabilities of downlink and uplink wireless data transfer (WDT) under various port selection strategies, including downlink signal-to-interference ratio-based port selection (DSPS), downlink energy-harvesting-power-based port selection (DEPS), uplink signal-to-noise ratio-based port selection (USPS), and uplink channel-based port selection (UCPS). To facilitate analysis, a step function approximation (SFA) method is proposed and then employed to obtain tractable expressions, including simplified integral forms. Moreover, lower bounds for the uplink WDT outage probability are derived. Numerical results validate the accuracy of the theoretical analysis and provide useful insights for system design.
{"title":"Performance Analysis of Fluid Antenna Multiple Access Assisted Wireless Powered Communication Network","authors":"Xiao Lin;Yizhe Zhao;Halvin Yang;Jie Hu","doi":"10.1109/JSAC.2025.3615178","DOIUrl":"10.1109/JSAC.2025.3615178","url":null,"abstract":"This paper investigates a novel wireless powered communication network (WPCN) enabled by fluid antenna multiple access (FAMA). In the proposed system, a hybrid access point (HAP) equipped with multiple fixed-position antennas (FPA) delivers integrated data and energy transfer (IDET) services. Each low-power device is equipped with a single fluid antenna (FA) and utilizes the harvested energy to support its uplink communication. A block-correlation fading channel model is adopted to analyze the outage probabilities of downlink and uplink wireless data transfer (WDT) under various port selection strategies, including downlink signal-to-interference ratio-based port selection (DSPS), downlink energy-harvesting-power-based port selection (DEPS), uplink signal-to-noise ratio-based port selection (USPS), and uplink channel-based port selection (UCPS). To facilitate analysis, a step function approximation (SFA) method is proposed and then employed to obtain tractable expressions, including simplified integral forms. Moreover, lower bounds for the uplink WDT outage probability are derived. Numerical results validate the accuracy of the theoretical analysis and provide useful insights for system design.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1382-1399"},"PeriodicalIF":17.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188389","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-29DOI: 10.1109/JSAC.2025.3615569
Tianyi Liao;Wei Guo;Hengtao He;Shenghui Song;Jun Zhang;Khaled B. Letaief
The fluid antenna system (FAS) is a disruptive technology for future wireless communication networks. This paper considers the joint optimization of beamforming matrices and antenna positions for weighted sum rate (WSR) maximization in fluid antenna (FA)-assisted multiuser multiple-input multiple-output (MU-MIMO) networks, which presents significant challenges due to the strong coupling between beamforming and FA positions, the non-concavity of the WSR objective function, and high computational complexity. To address these challenges, we first propose a novel block coordinate ascent (BCA)-based method that employs matrix fractional programming techniques to reformulate the original complex problem into a more tractable form. Then, we develop a parallel majorization maximization (MM) algorithm capable of optimizing all FA positions simultaneously. To further reduce computational costs, we propose a decentralized implementation based on the decentralized baseband processing (DBP) architecture. Simulation results demonstrate that our proposed algorithm not only achieves significant WSR improvements over conventional MIMO networks but also outperforms the existing method. Moreover, the decentralized implementation substantially reduces computation time while maintaining similar performance compared with the centralized implementation.
{"title":"Joint Beamforming and Antenna Position Optimization for Fluid Antenna-Assisted MU-MIMO Networks","authors":"Tianyi Liao;Wei Guo;Hengtao He;Shenghui Song;Jun Zhang;Khaled B. Letaief","doi":"10.1109/JSAC.2025.3615569","DOIUrl":"10.1109/JSAC.2025.3615569","url":null,"abstract":"The fluid antenna system (FAS) is a disruptive technology for future wireless communication networks. This paper considers the joint optimization of beamforming matrices and antenna positions for weighted sum rate (WSR) maximization in fluid antenna (FA)-assisted multiuser multiple-input multiple-output (MU-MIMO) networks, which presents significant challenges due to the strong coupling between beamforming and FA positions, the non-concavity of the WSR objective function, and high computational complexity. To address these challenges, we first propose a novel block coordinate ascent (BCA)-based method that employs matrix fractional programming techniques to reformulate the original complex problem into a more tractable form. Then, we develop a <italic>parallel</i> majorization maximization (MM) algorithm capable of optimizing all FA positions simultaneously. To further reduce computational costs, we propose a decentralized implementation based on the decentralized baseband processing (DBP) architecture. Simulation results demonstrate that our proposed algorithm not only achieves significant WSR improvements over conventional MIMO networks but also outperforms the existing method. Moreover, the decentralized implementation substantially reduces computation time while maintaining similar performance compared with the centralized implementation.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1209-1226"},"PeriodicalIF":17.2,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11184595","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145188395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-25DOI: 10.1109/JSAC.2025.3614195
Jae-Mo Kang;Il-Min Kim
Recently, fluid antenna system (FAS) exploiting flexible-location antennas within a given space has emerged as a key enabler for next-generation wireless communications and Internet-of-Things (IoT). In FAS, acquisition of precise channel state information (CSI) for all possible switchable locations, referred to as ports, is necessary, but demanding. Affirmatively, recent studies have revealed that by virtue of high spatial correlation among a number of ports, the CSI for all the ports can be acquired by estimating the CSI only for a small subset of the ports. However, an important and fundamental question still remains unanswered yet: then how much training is exactly required to estimate the CSI for all the ports in FAS? In this paper, we aim to rigorously answer this nontrivial question by developing a new channel estimation technique for FAS based on a latent domain representation of the CSI for the ports and by jointly optimizing training overhead, training sequences, and port switching. Our thorough analysis newly reveals that the training overhead required for estimating the CSI for all the ports is always less than the rank of spatial channel correlation matrix for all the ports and varies with signal-to-noise ratio (SNR). To alleviate the computational burden of the optimal solution, we also propose a low-complexity, yet near-optimal, solution for training design and port switching. Extensive simulation results confirm that in a practical situation with a large number of ports in a small size, the training overhead required for accurate CSI acquisition in FAS is within at most 10% of the number of ports at modest SNR, and the FAS outperforms the conventional fixed antenna system in terms of both the channel estimation accuracy and training overhead.
{"title":"How Much Training Is Required for Channel Estimation in Fluid Antenna System?","authors":"Jae-Mo Kang;Il-Min Kim","doi":"10.1109/JSAC.2025.3614195","DOIUrl":"10.1109/JSAC.2025.3614195","url":null,"abstract":"Recently, fluid antenna system (FAS) exploiting flexible-location antennas within a given space has emerged as a key enabler for next-generation wireless communications and Internet-of-Things (IoT). In FAS, acquisition of precise channel state information (CSI) for all possible switchable locations, referred to as ports, is necessary, but demanding. Affirmatively, recent studies have revealed that by virtue of high spatial correlation among a number of ports, the CSI for all the ports can be acquired by estimating the CSI only for a small subset of the ports. However, an important and fundamental question still remains unanswered yet: then how much training is exactly required to estimate the CSI for all the ports in FAS? In this paper, we aim to rigorously answer this nontrivial question by developing a new channel estimation technique for FAS based on a latent domain representation of the CSI for the ports and by jointly optimizing training overhead, training sequences, and port switching. Our thorough analysis newly reveals that the training overhead required for estimating the CSI for all the ports is always less than the rank of spatial channel correlation matrix for all the ports and varies with signal-to-noise ratio (SNR). To alleviate the computational burden of the optimal solution, we also propose a low-complexity, yet near-optimal, solution for training design and port switching. Extensive simulation results confirm that in a practical situation with a large number of ports in a small size, the training overhead required for accurate CSI acquisition in FAS is within at most 10% of the number of ports at modest SNR, and the FAS outperforms the conventional fixed antenna system in terms of both the channel estimation accuracy and training overhead.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1259-1275"},"PeriodicalIF":17.2,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=11180048","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-25DOI: 10.1109/JSAC.2025.3614206
Wenlong Sun;Shaohui Sun;Tong Shi;Xin Su;Rongke Liu
Recently, reconfigurable intelligent surfaces (RIS) technology has been researched to realize holographic communications, by utilizing its property of ultra-dense element spacing. However, the position-fixed RIS can only take advantage of phase-shift domain and reconfigurable holographic surfaces (RHS) can only take advantage of the amplitude domain. Furthermore, most of the previous researches only realize the holographic beamforming, which is only part of the holography theory. Therefore, to leverage the full potential of holography theory, a Fluid-RIS-enabled system is proposed to utilize holographic parameter reconstruction process to circumvent the challenging RIS channel estimation process. Furthermore, ideal and practical communication scenarios are considered, in which the two types of interference are different from the optical holography scenarios. The first type of interference stems from the background noise in the communication environment, and the second type of interference arises from the hardware impairment or phase shift error of the RIS system. To address these challenges, algorithms are proposed to eliminate the influence of second type of interference, even in the simultaneous presence of both interference sources. Consequently, we can perfectly reconstruct the channels’ information as well as the interferences’ information. Finally, simulation results verify the effectiveness and necessity of the proposed algorithms.
{"title":"Holographic Communications Enabled by Fluid RIS: Holographic Parameter Reconstruction and Beamforming","authors":"Wenlong Sun;Shaohui Sun;Tong Shi;Xin Su;Rongke Liu","doi":"10.1109/JSAC.2025.3614206","DOIUrl":"10.1109/JSAC.2025.3614206","url":null,"abstract":"Recently, reconfigurable intelligent surfaces (RIS) technology has been researched to realize holographic communications, by utilizing its property of ultra-dense element spacing. However, the position-fixed RIS can only take advantage of phase-shift domain and reconfigurable holographic surfaces (RHS) can only take advantage of the amplitude domain. Furthermore, most of the previous researches only realize the holographic beamforming, which is only part of the holography theory. Therefore, to leverage the full potential of holography theory, a Fluid-RIS-enabled system is proposed to utilize holographic parameter reconstruction process to circumvent the challenging RIS channel estimation process. Furthermore, ideal and practical communication scenarios are considered, in which the two types of interference are different from the optical holography scenarios. The first type of interference stems from the background noise in the communication environment, and the second type of interference arises from the hardware impairment or phase shift error of the RIS system. To address these challenges, algorithms are proposed to eliminate the influence of second type of interference, even in the simultaneous presence of both interference sources. Consequently, we can perfectly reconstruct the channels’ information as well as the interferences’ information. Finally, simulation results verify the effectiveness and necessity of the proposed algorithms.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"1432-1448"},"PeriodicalIF":17.2,"publicationDate":"2025-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145141554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-09-24DOI: 10.1109/JSAC.2025.3613672
Jiacheng Wang;Changyuan Zhao;Hongyang Du;Geng Sun;Jiawen Kang;Shiwen Mao;Dusit Niyato;Dong In Kim
Integrated sensing and communication (ISAC) uses the same software and hardware resources to achieve both communication and sensing functionalities. Thus, it stands as one of the core technologies of 6G and has garnered significant attention in recent years. In ISAC systems, a variety of machine learning models are trained to analyze and identify signal patterns, thereby ensuring reliable sensing and communications. However, considering factors such as communication rates, costs, and privacy, collecting sufficient training data from various ISAC scenarios for these models is impractical. Hence, this paper introduces a generative AI (GenAI) enabled robust data augmentation scheme. The scheme first employs a conditioned diffusion model trained on a limited amount of collected CSI data to generate new samples, thereby enhancing the sample quantity. Building on this, the scheme further utilizes another diffusion model to enhance the sample quality, thereby facilitating the data augmentation in scenarios where the original sensing data is insufficient and unevenly distributed. Moreover, we propose a novel algorithm to estimate the acceleration and jerk of signal propagation path length changes from CSI. We then use the proposed scheme to enhance the estimated parameters and detect the number of targets based on the enhanced data. The evaluation reveals that our scheme improves the detection performance by up to 70%, demonstrating reliability and robustness, which supports the deployment and practical use of the ISAC network.
{"title":"Generative AI Enabled Robust Data Augmentation for Wireless Sensing in ISAC Networks","authors":"Jiacheng Wang;Changyuan Zhao;Hongyang Du;Geng Sun;Jiawen Kang;Shiwen Mao;Dusit Niyato;Dong In Kim","doi":"10.1109/JSAC.2025.3613672","DOIUrl":"10.1109/JSAC.2025.3613672","url":null,"abstract":"Integrated sensing and communication (ISAC) uses the same software and hardware resources to achieve both communication and sensing functionalities. Thus, it stands as one of the core technologies of 6G and has garnered significant attention in recent years. In ISAC systems, a variety of machine learning models are trained to analyze and identify signal patterns, thereby ensuring reliable sensing and communications. However, considering factors such as communication rates, costs, and privacy, collecting sufficient training data from various ISAC scenarios for these models is impractical. Hence, this paper introduces a generative AI (GenAI) enabled robust data augmentation scheme. The scheme first employs a conditioned diffusion model trained on a limited amount of collected CSI data to generate new samples, thereby enhancing the sample quantity. Building on this, the scheme further utilizes another diffusion model to enhance the sample quality, thereby facilitating the data augmentation in scenarios where the original sensing data is insufficient and unevenly distributed. Moreover, we propose a novel algorithm to estimate the acceleration and jerk of signal propagation path length changes from CSI. We then use the proposed scheme to enhance the estimated parameters and detect the number of targets based on the enhanced data. The evaluation reveals that our scheme improves the detection performance by up to 70%, demonstrating reliability and robustness, which supports the deployment and practical use of the ISAC network.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"975-990"},"PeriodicalIF":17.2,"publicationDate":"2025-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145133688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Channel tracking in millimeter wave (mmWave) vehicular systems is crucial for maintaining robust vehicle-to-infrastructure (V2I) communication links, which can be leveraged to achieve high accuracy vehicle position and orientation tracking as a byproduct of communication. While prior work tends to simplify the system model by omitting critical system factors such as clock offsets, filtering effects, antenna array orientation offsets, and channel estimation errors, we address the challenges of a practical mmWave multiple-input multiple-output (MIMO) communication system between a single base station (BS) and a vehicle while tracking the vehicle’s position and orientation (PO) considering realistic driving behaviors. We first develop a channel tracking algorithm based on multidimensional orthogonal matching pursuit (MOMP) with factoring (F-MOMP) to reduce computational complexity and enable high-resolution channel estimates during the tracking stage, suitable for PO estimation. Then, we develop a network called VO-ChAT (Vehicle Orientation-Channel Attention for orientation Tracking), which processes the channel estimate sequence for orientation prediction. Afterward, a weighted least squares (WLS) problem that exploits the channel geometry is formulated to create an initial estimate of the vehicle’s 2D position. A second network named VP-ChAT (Vehicle Position-Channel Attention for position Tracking) refines the geometric position estimate. VP-ChAT is a Transformer inspired network processing the historical channel and position estimates to provide the correction for the initial geometric position estimate. The proposed solution is evaluated using ray-tracing generated channels in an urban canyon environment. In 80% of test cases, the proposed system achieves a 2D position tracking accuracy of 26 cm and maintains orientation errors below 0.5°.
毫米波（mmWave）车载系统中的信道跟踪对于维持稳健的车对基础设施（V2I）通信链路至关重要，这可以作为通信的副产品来实现高精度的车辆位置和方向跟踪。虽然之前的工作倾向于通过忽略关键系统因素（如时钟偏移、滤波效应、天线阵列方向偏移和信道估计误差）来简化系统模型，但我们解决了单个基站（BS）和车辆之间的实际毫米波多输入多输出（MIMO）通信系统的挑战，同时考虑到现实驾驶行为跟踪车辆的位置和方向（PO）。我们首先开发了一种基于多维正交匹配追踪（MOMP）和分解（F-MOMP）的信道跟踪算法，以降低计算复杂度并在跟踪阶段实现高分辨率信道估计，适用于PO估计。然后，我们开发了一个称为VO-ChAT （Vehicle orientation - channel Attention for orientation Tracking）的网络，该网络处理信道估计序列进行方向预测。然后，利用通道几何形状制定加权最小二乘（WLS）问题，以创建车辆二维位置的初始估计。第二个网络称为VP-ChAT (Vehicle position - channel Attention for position Tracking)，对几何位置估计进行了改进。VP-ChAT是一个变压器启发的网络，处理历史信道和位置估计，为初始几何位置估计提供校正。在城市峡谷环境中使用光线跟踪生成的通道对所提出的解决方案进行了评估。在80%的测试用例中，该系统实现了26 cm的2D位置跟踪精度，并将方向误差保持在0.5°以下。
{"title":"A Hybrid Model/Data-Driven Solution to Channel, Position, and Orientation Tracking in mmWave Vehicular Systems","authors":"Yun Chen;Nuria González-Prelcic;Takayuki Shimizu;Chinmay Mahabal","doi":"10.1109/JSAC.2025.3612354","DOIUrl":"10.1109/JSAC.2025.3612354","url":null,"abstract":"Channel tracking in millimeter wave (mmWave) vehicular systems is crucial for maintaining robust vehicle-to-infrastructure (V2I) communication links, which can be leveraged to achieve high accuracy vehicle position and orientation tracking as a byproduct of communication. While prior work tends to simplify the system model by omitting critical system factors such as clock offsets, filtering effects, antenna array orientation offsets, and channel estimation errors, we address the challenges of a practical mmWave multiple-input multiple-output (MIMO) communication system between a single base station (BS) and a vehicle while tracking the vehicle’s position and orientation (PO) considering realistic driving behaviors. We first develop a channel tracking algorithm based on multidimensional orthogonal matching pursuit (MOMP) with factoring (F-MOMP) to reduce computational complexity and enable high-resolution channel estimates during the tracking stage, suitable for PO estimation. Then, we develop a network called VO-ChAT (Vehicle Orientation-Channel Attention for orientation Tracking), which processes the channel estimate sequence for orientation prediction. Afterward, a weighted least squares (WLS) problem that exploits the channel geometry is formulated to create an initial estimate of the vehicle’s 2D position. A second network named VP-ChAT (Vehicle Position-Channel Attention for position Tracking) refines the geometric position estimate. VP-ChAT is a Transformer inspired network processing the historical channel and position estimates to provide the correction for the initial geometric position estimate. The proposed solution is evaluated using ray-tracing generated channels in an urban canyon environment. In 80% of test cases, the proposed system achieves a 2D position tracking accuracy of 26 cm and maintains orientation errors below 0.5°.","PeriodicalId":73294,"journal":{"name":"IEEE journal on selected areas in communications : a publication of the IEEE Communications Society","volume":"44 ","pages":"927-941"},"PeriodicalIF":17.2,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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