{"title":"Power Utilization in Open RAN: Key Findings From a USA Testbed","authors":"Saish Urumkar;Byrav Ramamurthy;Seshu Tirupathi;Sachin Sharma","doi":"10.1109/LCOMM.2025.3557715","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3557715","url":null,"abstract":"Open Radio Access Networks (Open RAN) provide flexible, scalable, and interoperable solutions to address the growing demands of mobile traffic while also aiming to reduce energy consumption. Most prior research on energy-efficient Open RAN has focused on switching techniques such as dynamic cell on/off strategies and adaptive resource allocation, primarily through simulations. This letter investigates Central Processing Unit (CPU) power utilization at the NodeB (base station) level, focusing on User Equipment (UE) connection states by making use of a USA testbed (i.e., POWDER testbed). Two scenarios are considered for the experimental setup: (1) a simulated virtual environment with a single high-powered device and (2) a physical hardware deployment using the separate low-power device for Open RAN. We present key findings from simulated and physical NodeB experiments conducted on the USA testbed, with real hardware. The findings include the relationship between power utilization and forced throughput, the impact of an increasing number of UEs on power utilization, the effects of different UE connection states (active, idle, or not connected), and the behavior of uplink and downlink throughput in both simulated and physical setups. Additionally, this letter introduces and validates power-law equations for power utilization in both setups, offering valuable insights into the effectiveness of UE connection state switching on NodeB CPU power utilization pattern. These findings contribute to the development of strategies for achieving energy-saving objectives in Open RAN.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1225-1229"},"PeriodicalIF":3.7,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10949489","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272797","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}
{"title":"Dynamic Convolution and Transformer Based Dual-Branch Coding in Semantic Communication System","authors":"Jiaxin Yang;Zhiquan Bai;Xiaodong Xu;Xuchao Teng;Mengying Sun;KyungSup Kwak","doi":"10.1109/LCOMM.2025.3557421","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3557421","url":null,"abstract":"Semantic communication is a potential key technology in 6G intelligent communication era. To reduce the information redundancy and improve the accuracy of text data transmission, this letter proposes a novel dual-branch joint source-channel coding model in semantic communication system that integrates dynamic convolution (DynConv) with Transformer architecture. The system utilizes the convolutional attention mechanism to capture the local semantic details and the Transformer self-attention mechanism for contextual associations within sentences. In particular, we further investigate the dimension allocation strategy between these two attention mechanisms, seeking the optimal balance between the recovery performance and complexity of the system. Simulation results demonstrate that, compared with the traditional communication system and the typical semantic communication system based on the standard Transformer, the proposed system achieves higher recovery performance, better robustness, and lower complexity.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 5","pages":"1161-1165"},"PeriodicalIF":3.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931313","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":"Robust Rate-Splitting-Based Precoding for Cell-Free MU-MIMO Systems","authors":"André R. Flores;Rodrigo C. de Lamare","doi":"10.1109/LCOMM.2025.3557743","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3557743","url":null,"abstract":"Cell-free (CF) multiuser multiple-input multiple-output (MU-MIMO) systems are an emerging technology that provides service simultaneously to multiple users but suffers from multiuser interference (MUI). In this work, we propose a robust transmit scheme based on rate-splitting (RS) for CF MU-MIMO systems in the presence of imperfect channel state information (CSI) and MUI. We also develop a robust linear precoder design for both private and common precoders based on the minimum mean square error (MMSE) criterion, which incorporates in its design statistical information about the imperfect CSI to provide extra robustness to RS-CF MU-MIMO systems. A statistical analysis is carried out to derive closed-form sum-rate expressions along with a study of the computational complexity of the proposed scheme. Simulation results show that the proposed scheme outperforms conventional robust and non-robust schemes.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1230-1234"},"PeriodicalIF":3.7,"publicationDate":"2025-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272794","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":"Wavelet-Based Three-Dimensional OTFS With Dual-Mode Index Modulation","authors":"Zhenxing Chen;Si Ouyang","doi":"10.1109/LCOMM.2025.3557036","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3557036","url":null,"abstract":"In this letter, we propose a new transmission scheme for the next-generation wireless communications called wavelet-based three-dimensional orthogonal time frequency space with dual-mode index modulation (W-3D-OTFS-DM-IM). To enhance the spectral efficiency, the transmitted information bits are mapped into the OTFS frame in the delay-doppler domain using a dual-mode index modulation with 3D signal constellations. The wavelet transform instead of the conventional Fourier transform is applied to achieve OTFS modulation for reduction of complexity and improvement of error performance. The Mallat algorithm is exploited to form the wavelet transform matrix. Simulation results show that the proposed W-3D-OTFS-DM-IM has obviously better bit error rate (BER) performance and spectral efficiency than the reference systems in the high-mobility communication scenarios.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 5","pages":"1151-1155"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143932233","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":"MASSFormer: Mobility-Aware Spectrum Sensing Using Transformer-Driven Tiered Structure","authors":"Dimpal Janu;Faisel Mushtaq;Sandeep Mandia;Kuldeep Singh;Sandeep Kumar","doi":"10.1109/LCOMM.2025.3557217","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3557217","url":null,"abstract":"In this paper, we develop a novel mobility-aware transformer-driven tiered structure (MASSFormer) based cooperative spectrum sensing method that effectively models the spatio-temporal dynamics of user movements. Unlike existing methods, our method considers a dynamic scenario involving mobile primary users (PUs) and secondary users (SUs) and addresses the complexities introduced by user mobility. The transformer architecture utilizes an attention mechanism, allowing the proposed method to model the temporal dynamics of user mobility by effectively capturing long-range dependencies. The proposed method first computes tokens from the sequence of covariance matrices (CMs) for each SU. It processes them in parallel using the SU-transformer to learn the spatio-temporal features at SU-level. Subsequently, the collaborative transformer learns the group-level PU state from all SU-level feature representations. The main goal of predicting the PU states at each SU-level and group-level is to improve detection performance even more. The proposed method is tested under imperfect reporting channel scenarios to show robustness. The efficacy of our method is validated with simulation results that demonstrate its higher performance compared to existing methods in terms of detection probability <inline-formula> <tex-math>$P_{d}$ </tex-math></inline-formula>, sensing error, and classification accuracy (CA).","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1220-1224"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272796","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":"Physical IoU-Based YOLO Network for Shortwave Communication Burst Signal Recognition","authors":"Xiaojun Zhu;Yinsen Luan;Paihang Zhao;Tao Tang;Zhidong Wu","doi":"10.1109/LCOMM.2025.3557043","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3557043","url":null,"abstract":"Shortwave communication plays a critical role in military and emergency applications. However, the complex nature of shortwave transmission channels makes automatic burst signal recognition particularly challenging, especially in non-cooperative scenarios. This letter presents an optimized recognition method based on the You Only Look Once (YOLO) network, which accurately identifies signal types while improving the precision of burst time detection. A Physical Intersection over Union (PIoU) is proposed by leveraging the bounding box’s left edge, corresponding to signal burst time, to refine bounding box regression and resolve ambiguities in conventional IoUs. Experiments show the proposed PIoU improves the accuracy of burst time detection by 10.44% under Signal-to-Noise Ratios (SNRs) from -20dB to 18dB, compared to the state-of-the-art IoU methods. Further tests across 8 shortwave communication channels confirm consistent improvements of burst time detection, while other metrics such as Precision, Recall, mean Average Precision at 50% IoU(mAP50), and mAP95 are maintained. These advancements significantly benefit signal decoding and information restoration.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 5","pages":"1156-1160"},"PeriodicalIF":3.7,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931314","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 Joint Source-Channel Coding of Underwater Image Enhancement in AUV Swarms","authors":"Zhenguo Zhang;Guang Liu;Minghui Wang;Bo Chen;Zesheng Liu;Xiaojie Zhang","doi":"10.1109/LCOMM.2025.3556673","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3556673","url":null,"abstract":"Underwater images commonly suffer from visual degradation due to the complexities of the underwater imaging and transmission environments. To address this issue, we propose a lightweight system for underwater image enhancement and transmission tailored for autonomous underwater vehicle swarms, improving both image quality and communication efficiency with surface equipment. The proposed model enables a target-oriented multi-space feature encoding network to process degraded pixels, followed by a reinforcement learning-based bandwidth allocation network that optimizes feature distribution under constrained bandwidth conditions. Simulation results demonstrate that the proposed system significantly enhances the speed and effectiveness of image recovery under varying channel conditions.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 5","pages":"1146-1150"},"PeriodicalIF":3.7,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931311","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}
Chaorong Zhang;Ieok Cheng Wong;Benjamin K. Ng;Chan-Tong Lam
{"title":"LEO Satellite-Assisted GSSK With Optimized Antenna Combination Selections and Detector","authors":"Chaorong Zhang;Ieok Cheng Wong;Benjamin K. Ng;Chan-Tong Lam","doi":"10.1109/LCOMM.2025.3556874","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3556874","url":null,"abstract":"This letter introduces the LEO satellite-assisted generalized space shift keying (LEO-GSSK) scheme, as a trade-off wireless scheme with satisfactory spectral efficiency and bit error rate (BER) performance. We adopt advanced antenna combination selection strategies to further decrease complexity and enhance BER performance. Moreover, a low-complexity detector is designed in this investigated scheme while maintaining the acceptable BER. This detector also reduces complexity and mitigates the side effects of imperfect CSI estimation. The analytical performance of the LEO-GSSK scheme is presented in this letter, along with some interesting insights and conclusions given in simulation results. Besides, to approach practical wireless environment, the imperfect CSI estimation is considered in simulation results. The theoretical analysis and simulation results indicate that the LEO-GSSK scheme with novel antenna combination selection and detector designs, outperforms traditional schemes, offering a promising solution to meet the high data rate and reliable connectivity demands of satellite communications.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1210-1214"},"PeriodicalIF":3.7,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272699","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}
Trinh Van Chien;Nguyen Minh Quan;Oh-Soon Shin;Van-Dinh Nguyen
{"title":"Metaheuristic Optimization of Trajectory and Dynamic Time Splitting for UAV Communication Systems","authors":"Trinh Van Chien;Nguyen Minh Quan;Oh-Soon Shin;Van-Dinh Nguyen","doi":"10.1109/LCOMM.2025.3556714","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3556714","url":null,"abstract":"The integration of unmanned aerial vehicles (UAVs) into wireless communication systems has emerged as a transformative approach, promising cost-efficient connectivity. This letter addresses the optimization of the dynamic time-splitting ratio and flight trajectory for a communication system linking a ground base station to the UAV equipped with backscatter devices (referred to as UB), and from UB to an end user. Given the inherent non-convexity of the problem, we develop two meta-heuristic-based approaches inspired by genetic algorithm and particle swarm optimization to enhance the total achievable rate while reducing computational complexity. Numerical results demonstrate the effectiveness of these meta-heuristic solutions, showcasing significant improvements in the achievable rate and computation time compared to existing benchmarks.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1200-1204"},"PeriodicalIF":3.7,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272772","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":"Generalized Extended Welch Bound for Multi-Cell Non-Orthogonal Sequence Sets","authors":"Bingsheng Shen;Kaiqiang Liu;Zhi Gu;Yang Yang;Zhengchun Zhou","doi":"10.1109/LCOMM.2025.3555222","DOIUrl":"https://doi.org/10.1109/LCOMM.2025.3555222","url":null,"abstract":"Sequence sets with minimum total squared correlation (TSC) have important application in communications. In a multi-cell system, due to the difference in channel strength between the home cell and the neighboring cells, the TSC can be expressed as the sum of squares of weighted correlations among sequences. In this letter, we obtain a closed-form expression for the lower bound of weighted TSC under multi-cell systems which can be regarded as a generalization of the extended Welch bound, namely generalized extended welch bound (GEWB). Moreover, we find a class of sequence sets whose parameters can achieve the theoretical lower bound of the weighted TSC, indicating that the derived GEWB is tight.","PeriodicalId":13197,"journal":{"name":"IEEE Communications Letters","volume":"29 6","pages":"1176-1180"},"PeriodicalIF":3.7,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272911","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}