Pub Date : 2025-12-31DOI: 10.1109/LCOMM.2025.3649890
Youngmin Kim;Yeong Jun Kim
Extremely large antenna arrays, operating at mmWave or sub-THz frequency bands, are essential to meet the ambitious performance targets envisioned for sixth-generation (6G) wireless networks, but they face near-field challenges due to spherical wavefronts. This study proposes a novel beam-tracking method for extremely large uniform planar arrays (ELUPAs) using an overlapped subarray configuration. The method tracks the beam by estimating the spatial response parameters, which include both angle and range, using the first-order differential product between signals from closely spaced and overlapped subarrays. A single-antenna-element displacement between overlapped subarrays introduces phase symmetry, enabling robust and efficient parameter estimation for near-field beam tracking.
{"title":"A Near-Field Beam-Tracking Technique for Extremely Large Uniform Planar Array Systems With Overlapped Subarray Configuration","authors":"Youngmin Kim;Yeong Jun Kim","doi":"10.1109/LCOMM.2025.3649890","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3649890","url":null,"abstract":"Extremely large antenna arrays, operating at mmWave or sub-THz frequency bands, are essential to meet the ambitious performance targets envisioned for sixth-generation (6G) wireless networks, but they face near-field challenges due to spherical wavefronts. This study proposes a novel beam-tracking method for extremely large uniform planar arrays (ELUPAs) using an overlapped subarray configuration. The method tracks the beam by estimating the spatial response parameters, which include both angle and range, using the first-order differential product between signals from closely spaced and overlapped subarrays. A single-antenna-element displacement between overlapped subarrays introduces phase symmetry, enabling robust and efficient parameter estimation for near-field beam tracking.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"747-751"},"PeriodicalIF":4.4,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929367","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}
Pub Date : 2025-12-30DOI: 10.1109/LCOMM.2025.3649705
Yi Kuang;Lingya Liu;Jing Xu
In reconfigurable intelligent surface (RIS)-assisted millimeter-wave (mmWave) communications, the line of sight (LoS) probabilities of the direct base station (BS)-user and reflective BS-RIS-user links are correlated because common obstacles may simultaneously block both links. To reduce the probability that the same obstacles block both links, the RIS should not be deployed close to the BS. However, increasing the BS-RIS distance significantly elevates the path loss along the reflective BS-RIS-user link, thereby degrading the system performance. To compromise the LoS probability and path loss of the reflective link when the direct link is blocked, the three-dimensional (3D) RIS placement problem in a single-cell mmWave system with randomly sized and distributed obstacles is investigated. We derived the integral expressions for the joint blockage probability of both links, the cell coverage probability, and the ergodic spectrum efficiency. With the derived expressions, the optimal RIS 3D deployment range can be obtained by numerical integration and exhaustive grid search. Numerical results validate the theoretical derivations and the fundamental trade-off between the LoS probability and the path loss.
{"title":"Optimal 3-D Deployment Range of RIS in mmWave Communications With Random Blockages","authors":"Yi Kuang;Lingya Liu;Jing Xu","doi":"10.1109/LCOMM.2025.3649705","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3649705","url":null,"abstract":"In reconfigurable intelligent surface (RIS)-assisted millimeter-wave (mmWave) communications, the line of sight (LoS) probabilities of the direct base station (BS)-user and reflective BS-RIS-user links are correlated because common obstacles may simultaneously block both links. To reduce the probability that the same obstacles block both links, the RIS should not be deployed close to the BS. However, increasing the BS-RIS distance significantly elevates the path loss along the reflective BS-RIS-user link, thereby degrading the system performance. To compromise the LoS probability and path loss of the reflective link when the direct link is blocked, the three-dimensional (3D) RIS placement problem in a single-cell mmWave system with randomly sized and distributed obstacles is investigated. We derived the integral expressions for the joint blockage probability of both links, the cell coverage probability, and the ergodic spectrum efficiency. With the derived expressions, the optimal RIS 3D deployment range can be obtained by numerical integration and exhaustive grid search. Numerical results validate the theoretical derivations and the fundamental trade-off between the LoS probability and the path loss.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"767-771"},"PeriodicalIF":4.4,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929494","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}
Pub Date : 2025-12-29DOI: 10.1109/LCOMM.2025.3649257
Zexiao Lu;Bin Wu;Xiaoxin Liang;Xiaoping Zhou;Guangxi Liu
The performance of Wi-Fi multi-user MIMO (MU-MIMO) systems critically depends on timely and accurate channel state information (CSI) feedback, but its practical deployment is fundamentally constrained by the trade-off between performance and complexity. Singular value decomposition (SVD)-based schemes provide near-optimal performance but incur prohibitive computational cost, whereas QR decomposition (QRD)-based schemes offer hardware-friendly but cannot support power allocation. This letter proposes a novel sorted QRD (SQRD)-based scheme, retaining the low complexity of QRD while enabling power allocation. Simulations demonstrate that the proposed approach achieves performance comparable to the SVD benchmark, offering a low-complexity and hardware-friendly solution for next-generation Wi-Fi.
{"title":"Low-Complexity SQRD-Based CSI Feedback for Wi-Fi MU-MIMO","authors":"Zexiao Lu;Bin Wu;Xiaoxin Liang;Xiaoping Zhou;Guangxi Liu","doi":"10.1109/LCOMM.2025.3649257","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3649257","url":null,"abstract":"The performance of Wi-Fi multi-user MIMO (MU-MIMO) systems critically depends on timely and accurate channel state information (CSI) feedback, but its practical deployment is fundamentally constrained by the trade-off between performance and complexity. Singular value decomposition (SVD)-based schemes provide near-optimal performance but incur prohibitive computational cost, whereas QR decomposition (QRD)-based schemes offer hardware-friendly but cannot support power allocation. This letter proposes a novel sorted QRD (SQRD)-based scheme, retaining the low complexity of QRD while enabling power allocation. Simulations demonstrate that the proposed approach achieves performance comparable to the SVD benchmark, offering a low-complexity and hardware-friendly solution for next-generation Wi-Fi.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"777-781"},"PeriodicalIF":4.4,"publicationDate":"2025-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145929591","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}
Pub Date : 2025-12-26DOI: 10.1109/LCOMM.2025.3648494
Dan Wang;Xiaopeng Jiao;Chenyu Wang;Jianjun Mu
To recover the sequence $boldsymbol {x}$ from several noisy traces of $boldsymbol {x}$ corrupted by random deletions, the bitwise majority alignment (BMA) algorithm reconstructs each bit sequentially by taking a majority vote on its value in all traces. For each bit, only one bit in each trace is used to make a decision in BMA, and the correlation with its neighbors is ignored. In this letter, we develop a novel multi-bit decision-based BMA (MBD-BMA) for trace reconstruction. The proposed MBD-BMA uses multiple subsequent bits from each trace to reconstruct a bit of $boldsymbol {x}$ more precisely than BMA. The main idea of MBD-BMA is to use a binary tree to represent all possible cases of the subsequent bits for the bit to be reconstructed, with a weight assigned to each case, i.e., each branch of the binary tree. The bit is then reconstructed by using the minimum-weight branch. Simulation results show that the Levenshtein error rate of the proposed MBD-BMA is significantly lower than that of BMA, while the increased complexity of MBD-BMA is relatively low.
{"title":"Multi-Bit Decision-Based Bitwise Majority Alignment Algorithm for Trace Reconstruction","authors":"Dan Wang;Xiaopeng Jiao;Chenyu Wang;Jianjun Mu","doi":"10.1109/LCOMM.2025.3648494","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3648494","url":null,"abstract":"To recover the sequence <inline-formula> <tex-math>$boldsymbol {x}$ </tex-math></inline-formula> from several noisy traces of <inline-formula> <tex-math>$boldsymbol {x}$ </tex-math></inline-formula> corrupted by random deletions, the bitwise majority alignment (BMA) algorithm reconstructs each bit sequentially by taking a majority vote on its value in all traces. For each bit, only one bit in each trace is used to make a decision in BMA, and the correlation with its neighbors is ignored. In this letter, we develop a novel multi-bit decision-based BMA (MBD-BMA) for trace reconstruction. The proposed MBD-BMA uses multiple subsequent bits from each trace to reconstruct a bit of <inline-formula> <tex-math>$boldsymbol {x}$ </tex-math></inline-formula> more precisely than BMA. The main idea of MBD-BMA is to use a binary tree to represent all possible cases of the subsequent bits for the bit to be reconstructed, with a weight assigned to each case, i.e., each branch of the binary tree. The bit is then reconstructed by using the minimum-weight branch. Simulation results show that the Levenshtein error rate of the proposed MBD-BMA is significantly lower than that of BMA, while the increased complexity of MBD-BMA is relatively low.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"692-696"},"PeriodicalIF":4.4,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886586","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}
Pub Date : 2025-12-25DOI: 10.1109/LCOMM.2025.3646108
Lifang He;Yunhan Pei;Gang Zhang;Yongqi Guo
To address the issues of low transmission rate and poor bit error rate (BER) performance in traditional Differential Chaos Shift Keying (DCSK) systems, this letter proposes a novel position-index-modulation-based DCSK scheme. Each row of the Walsh code matrix is used to perform a Kronecker product with the initial reference signal to generate multiple orthogonal signals. Each orthogonal signal independently undergoes position index modulation and carries modulated bits to transmit information. Position index modulation labels each time slot of each subcarrier in the system frame structure as a unique position indexed sequentially. According to the rules of $K$ -combination mapping, one or more active positions are selected from all positions to transmit corresponding orthogonal signals. At the receiver, a sliding average denoising technique is introduced to reduce noise variance and enhance system reliability. Additionally, BER expressions are derived under additive white Gaussian noise (AWGN) channels and multipath Rayleigh fading channels. Simulation results demonstrate that the proposed system achieves higher transmission rates and better BER performance compared with several DCSK-based schemes proposed in recent years.
{"title":"A Modulated Position-Indexed Differential Chaos Shift Keying System With Enhanced BER and Throughput","authors":"Lifang He;Yunhan Pei;Gang Zhang;Yongqi Guo","doi":"10.1109/LCOMM.2025.3646108","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3646108","url":null,"abstract":"To address the issues of low transmission rate and poor bit error rate (BER) performance in traditional Differential Chaos Shift Keying (DCSK) systems, this letter proposes a novel position-index-modulation-based DCSK scheme. Each row of the Walsh code matrix is used to perform a Kronecker product with the initial reference signal to generate multiple orthogonal signals. Each orthogonal signal independently undergoes position index modulation and carries modulated bits to transmit information. Position index modulation labels each time slot of each subcarrier in the system frame structure as a unique position indexed sequentially. According to the rules of <inline-formula> <tex-math>$K$ </tex-math></inline-formula>-combination mapping, one or more active positions are selected from all positions to transmit corresponding orthogonal signals. At the receiver, a sliding average denoising technique is introduced to reduce noise variance and enhance system reliability. Additionally, BER expressions are derived under additive white Gaussian noise (AWGN) channels and multipath Rayleigh fading channels. Simulation results demonstrate that the proposed system achieves higher transmission rates and better BER performance compared with several DCSK-based schemes proposed in recent years.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"612-616"},"PeriodicalIF":4.4,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145830870","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}
Transmission of large volume of multimodal data (MMD) in real-time wireless systems requires statistical guarantees on latency, as well as consideration of individual data profiles present in MMD to ensure high reliability of the overall system. Therefore, we consider a setup with MMD, i.e., heterogeneous data profiles and propose two schemes: Compression and transmission (CT) and parallel compression and transmission (PCT), to analyse and optimize the latency incurred during uplink (UL) MMD transmission. CT follows a sequential process for compression and transmission, while PCT executes them in parallel. A non-convex optimization problem is formulated to minimize the UL latency. The results show that the proposed MMD schemes is advantageous over unimodal data consideration, as it prevents over-provisioning. Specifically, PCT reduces latency up to 68% for 0.9999 reliability level as compared to CT.
{"title":"Uplink Latency Characterization of Multimodal Data Transmission in Real-Time Wireless Systems","authors":"Suraj Suman;Rakesh Kumar;Anjali Shaw;Petar Popovski","doi":"10.1109/LCOMM.2025.3647966","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3647966","url":null,"abstract":"Transmission of large volume of multimodal data (MMD) in real-time wireless systems requires statistical guarantees on latency, as well as consideration of individual data profiles present in MMD to ensure high reliability of the overall system. Therefore, we consider a setup with MMD, i.e., heterogeneous data profiles and propose two schemes: Compression and transmission (CT) and parallel compression and transmission (PCT), to analyse and optimize the latency incurred during uplink (UL) MMD transmission. CT follows a sequential process for compression and transmission, while PCT executes them in parallel. A non-convex optimization problem is formulated to minimize the UL latency. The results show that the proposed MMD schemes is advantageous over unimodal data consideration, as it prevents over-provisioning. Specifically, PCT reduces latency up to 68% for 0.9999 reliability level as compared to CT.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"687-691"},"PeriodicalIF":4.4,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886587","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}
Pub Date : 2025-12-24DOI: 10.1109/LCOMM.2025.3647941
Junwei Zhu;Fei Han;Yuqing Guo;Ying Wang
The existing works concerning movable antenna (MA) arrays often stipulate a half-wavelength minimum antenna spacing to avoid mutual coupling (MC) between antennas. This letter unveils the potential performance improvement of MA arrays by strategically leveraging MC for the first time. Firstly, the impacts of MC are precisely characterized by the MC matrix, which is derived based on rigorous circuit and antenna theories. Upon this approach, the maximization of the sum rate is formulated as a problem, where the minimum-spacing constraints for antennas are naturally removed. Subsequently, a hybrid convex optimization and particle swarm optimization (CO-PSO) is proposed to tackle the proposed problem efficiently. Simulations results are provided to validate the robustness of our proposed CO-PSO algorithm. These results demonstrate that MC can enhance the spectral efficiency of MA arrays by approximately 1.75 bps/Hz, thus highlighting the potential of MC in improving the capacity of MA-assisted wireless communications.
{"title":"Mutual Coupling-Enhanced Movable Antenna Arrays: Breaking Minimum-Spacing Constraints","authors":"Junwei Zhu;Fei Han;Yuqing Guo;Ying Wang","doi":"10.1109/LCOMM.2025.3647941","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3647941","url":null,"abstract":"The existing works concerning movable antenna (MA) arrays often stipulate a half-wavelength minimum antenna spacing to avoid mutual coupling (MC) between antennas. This letter unveils the potential performance improvement of MA arrays by strategically leveraging MC for the first time. Firstly, the impacts of MC are precisely characterized by the MC matrix, which is derived based on rigorous circuit and antenna theories. Upon this approach, the maximization of the sum rate is formulated as a problem, where the minimum-spacing constraints for antennas are naturally removed. Subsequently, a hybrid convex optimization and particle swarm optimization (CO-PSO) is proposed to tackle the proposed problem efficiently. Simulations results are provided to validate the robustness of our proposed CO-PSO algorithm. These results demonstrate that MC can enhance the spectral efficiency of MA arrays by approximately 1.75 bps/Hz, thus highlighting the potential of MC in improving the capacity of MA-assisted wireless communications.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"672-676"},"PeriodicalIF":4.4,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886671","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}
Pub Date : 2025-12-24DOI: 10.1109/LCOMM.2025.3648306
Yaoxian Gao;Yongmei Sun;Yuefeng Ji
In quantum-classical coexistence systems, classical noise and system loss can significantly affect the performance of quantum key distribution (QKD), while the fixed-parameter QKD (FPQ) cannot adapt to varying conditions. In this letter, we propose a local search algorithm (LSA) for QKD to optimize the parameters in wavelength division multiplexing (WDM) and space division multiplexing (SDM) systems. Simulation results show that LSA can achieve 99.9% performance of the exhaustive search algorithm, while significantly reducing computational complexity. Moreover, LSA improves QKD performance by 31.9% over standard single mode fiber and 24.5% over multicore fiber in quantum-classical coexistence systems.
{"title":"Parameter Optimization of Quantum Key Distribution in Quantum-Classical WDM-SDM Coexistence Systems","authors":"Yaoxian Gao;Yongmei Sun;Yuefeng Ji","doi":"10.1109/LCOMM.2025.3648306","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3648306","url":null,"abstract":"In quantum-classical coexistence systems, classical noise and system loss can significantly affect the performance of quantum key distribution (QKD), while the fixed-parameter QKD (FPQ) cannot adapt to varying conditions. In this letter, we propose a local search algorithm (LSA) for QKD to optimize the parameters in wavelength division multiplexing (WDM) and space division multiplexing (SDM) systems. Simulation results show that LSA can achieve 99.9% performance of the exhaustive search algorithm, while significantly reducing computational complexity. Moreover, LSA improves QKD performance by 31.9% over standard single mode fiber and 24.5% over multicore fiber in quantum-classical coexistence systems.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"697-701"},"PeriodicalIF":4.4,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886682","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}
Pub Date : 2025-12-24DOI: 10.1109/LCOMM.2025.3648035
Himani Verma;Kamal Singh;Ranjan K. Mallik
Coherent free-space optical (FSO) communication is recognized as a key enabler for ultra-high-capacity fronthaul and backhaul links in next-generation wireless networks. Spectrally efficient $M$ –ary quadrature amplitude modulation (MQAM) formats are well-suited for these links. However, theoretical analyses of adaptive MQAM transmissions over terrestrial FSO channels remain limited. In this letter, we first derive the spectral efficiency limit of adaptive unconstrained MQAM over gamma-gamma turbulence with pointing error. We then show that adaptive transmissions using only six square MQAM constellations performs close to the theoretical limit (within ${0.10 - 0.12}$ bits/s/Hz) across a wide range of signal-to-noise ratios and channel conditions.
{"title":"Maximum Spectral Efficiency With Adaptive MQAM Transmissions Over Terrestrial Coherent FSO Links","authors":"Himani Verma;Kamal Singh;Ranjan K. Mallik","doi":"10.1109/LCOMM.2025.3648035","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3648035","url":null,"abstract":"Coherent free-space optical (FSO) communication is recognized as a key enabler for ultra-high-capacity fronthaul and backhaul links in next-generation wireless networks. Spectrally efficient <inline-formula> <tex-math>$M$ </tex-math></inline-formula>–ary quadrature amplitude modulation (MQAM) formats are well-suited for these links. However, theoretical analyses of adaptive MQAM transmissions over terrestrial FSO channels remain limited. In this letter, we first derive the spectral efficiency limit of adaptive unconstrained MQAM over gamma-gamma turbulence with pointing error. We then show that adaptive transmissions using only six square MQAM constellations performs close to the theoretical limit (within <inline-formula> <tex-math>${0.10 - 0.12}$ </tex-math></inline-formula> bits/s/Hz) across a wide range of signal-to-noise ratios and channel conditions.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"677-681"},"PeriodicalIF":4.4,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886670","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}
This letter presents the first study on the feasibility of automatic modulation classification (AMC) for orthogonal time-sequency multiplexing (OTSM). Through rigorous analyses, it is observed that Walsh-Hadamard transform (WHT) spreading induces global feature mixing, severely degrading modulation-specific structures. Analyses reveal up to a 93.55% loss in magnitude-domain distinctiveness using Wasserstein distance and show that performance degradation intensifies with the presence of correlated modulation schemes. Benchmarking with a dual-channel vision-transformer (ViT) in the extended vehicular A (EVA) channel shows that OTSM underperforms OTFS by 8.58% (100 km/h) and 9.32% (500 km/h) on average. Even with larger frames ($64 times 64$ ) and doubled training data, OTSM accuracy saturates at 39.13%, far below OTFS’s 54.59%. Furthermore, impact of timing and carrier frequency offsets in OTSM-based AMC systems are evaluated and compared with OTFS and OFDM counterparts under similar channel conditions. The findings underscore that WHT-induced feature homogenization, not channel impairment, is the fundamental classification bottleneck.
{"title":"On the Effect of Walsh–Hadamard Spreading on Modulation Classification in OTSM Transceivers","authors":"Tonmoy Rajkhowa;Sanjeev Sharma;Kuntal Deka;Om Jee Pandey","doi":"10.1109/LCOMM.2025.3647601","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3647601","url":null,"abstract":"This letter presents the first study on the feasibility of automatic modulation classification (AMC) for orthogonal time-sequency multiplexing (OTSM). Through rigorous analyses, it is observed that Walsh-Hadamard transform (WHT) spreading induces global feature mixing, severely degrading modulation-specific structures. Analyses reveal up to a 93.55% loss in magnitude-domain distinctiveness using Wasserstein distance and show that performance degradation intensifies with the presence of correlated modulation schemes. Benchmarking with a dual-channel vision-transformer (ViT) in the extended vehicular A (EVA) channel shows that OTSM underperforms OTFS by 8.58% (100 km/h) and 9.32% (500 km/h) on average. Even with larger frames (<inline-formula> <tex-math>$64 times 64$ </tex-math></inline-formula>) and doubled training data, OTSM accuracy saturates at 39.13%, far below OTFS’s 54.59%. Furthermore, impact of timing and carrier frequency offsets in OTSM-based AMC systems are evaluated and compared with OTFS and OFDM counterparts under similar channel conditions. The findings underscore that WHT-induced feature homogenization, not channel impairment, is the fundamental classification bottleneck.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"30 ","pages":"652-656"},"PeriodicalIF":4.4,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145886669","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：