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Adaptive Hybrid-Field Channel Estimation in THz XL-MIMO Systems

IEEE Transactions on Vehicular technology 2025年

作者： Lu, Jiayi Zhang, Jiayi Lei, Hao Xiao, Huahua Ai, Bo State Key Laboratory of Advanced Rail Autonomous Operation China Beijing Jiaotong University School of Electronics and Information Engineering Beijing100044 China ZTE Corporation State Key Laboratory of Mobile Network and Mobile Multimedia Technology Shenzhen518055 China

In this correspondence, we delve into a hybrid-field channel model for the extremely large-scale multiple-input multiple-output (XL-MIMO) system and formulate the channel estimation problem within a multi-carrier scenario. Additionally, we introduce a near-field prioritized adaptive scheme to address the issue of reliance on prior information regarding the exact numbers of near-field and far-field paths, featuring a noise-level-based stopping criterion. Focusing on narrowband and wideband scenarios, we design two algorithms within this adaptive framework based on the multiple measurement vector model. Numerical results demonstrate that the proposed adaptive hybrid-field channel estimation strategies surpass existing methods in channel estimation accuracy while maintaining low computational complexity. © 1967-2012 IEEE.

关键词： Channel estimation

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Downlink Performance Analysis of Extremely Large-Scale MIMO-OFDM Systems for High-Speed Railway

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IEEE Transactions on Vehicular technology 2025年

作者： Yi, Wenhui Zhang, Jiayi Wang, Zhe Xiao, Huahua Ai, Bo State Key Laboratory of Advanced Rail Autonomous Operation China Beijing Jiaotong University School of Electronics and Information Engineering Beijing100044 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation Shenzhen518055 China

The potential of extremely large-scale multiple-input multiple-output (XL-MIMO) systems to enhance the performance of high-speed railway (HSR) wireless networks is vast. In this correspondence, we examine the performance characteristics of the XL-MIMO-OFDM HSR system, focusing on uniform planar array (UPA) and uniform linear array (ULA) configurations. Considering the multipath spherical wave channel model, we develop a system model that accounts for the Doppler frequency offset (DFO) caused by train movement. Our analysis includes the performance of effective degrees of freedom (EDoF), deriving closed-form expressions for both UPA- and ULA-based systems. Additionally, we investigate the integration of XL-MIMO with orthogonal frequency-division multiplexing (OFDM), which enhances the signal-to-interference plus noise ratio (SINR) and spectral efficiency (SE) of individual base stations. Simulation results demonstrate the superior EDoF performance of UPA- and ULA-based XL-MIMO-OFDM systems. Moreover, the intercarrier interference resulting from train movement increases with speed, and the degradation in signal quality caused by this interference can be mitigated by configuring the XL-MIMO-OFDM system. Notably, the adoption of XL-MIMO technology with a near-field channel model significantly improves coverage reliability compared to traditional MIMO configurations using a far-field channel model. © 1967-2012 IEEE.

关键词： Signal to noise ratio

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Superior carrier mobility and photogalvanic effect of Si9C15 and WSSe heterojunctions

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Materials Today communications 2025年 46卷

作者： Meng, Haotian Cui, Zhen Wu, Pengfei Zhang, Shuang Wang, Lu School of Automation and Information Engineering Xi'an University of Technology Xi'an710048 China Xi'an Key Laboratory of Wireles Optical Communication and Network Research Xi'an University of Technology Xi'an710048 China

Based on first-principles calculations, this study explores the structural stability, electronic properties, optical characteristics and mechanical properties of the Si₉C₁₅/WSSe heterojunction. Quantum transport simulations are also performed to determine the photogenerated current and the extinction ratio. Identified as a direct bandgap semiconductor, the Si₉C₁₅/WSSe heterojunction has a bandgap of 2.01 eV. Ab initio molecular dynamics results confirm the good stability of the heterojunction. The electron mobility of the Si₉C₁₅/WSSe heterostructure reaches 1544 cm²/Vs along the armchair direction and 1024 cm²/Vs along the zigzag direction. In comparison to individual materials, the Si₉C₁₅/WSSe heterojunction exhibits enhanced absorption of solar radiation within the visible spectrum. The photodetector utilizing the Si₉C₁₅/WSSe heterojunction achieves a peak photogenerated current of 5.43 a₀²/photon and an optimal extinction ratio of 11.7, the high sensitivity to polarization is demonstrated, being significantly influenced by changes in the polarization angle θ and photon energy. © 2025

关键词： Heterojunctions

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Improving Speech Enhancement by Cross- and Sub-band Processing with State Space Model

arXiv

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arXiv 2025年

作者： Li, Jizhen Tu, Weiping Yang, Yuhong Xu, Xinmeng Zhang, Yiqun Ren, Yanzhen NERCMS School of Computer Science Hubei Luojia Laboratory Wuhan University China Hubei Key Laboratory of Multimedia and Network Communication Engineering Wuhan University China School of Cyber Science and Engineering Wuhan University China

Recently, the state space model (SSM) represented by Mamba has shown remarkable performance in long-term sequence modeling tasks, including speech enhancement. However, due to substantial differences in sub-band features, applying the same SSM to all sub-bands limits its inference capability. Additionally, when processing each time frame of the time-frequency representation, the SSM may forget certain high-frequency information of low energy, making the restoration of structure in the high-frequency bands challenging. For this reason, we propose Cross- and Sub-band Mamba (CSMamba). To assist the SSM in handling different sub-band features flexibly, we propose a band split block that splits the full-band into four sub-bands with different widths based on their information similarity. We then allocate independent weights to each subband, thereby reducing the inference burden on the SSM. Furthermore, to mitigate the forgetting of low-energy information in the high-frequency bands by the SSM, we introduce a spectrum restoration block that enhances the representation of the cross-band features from multiple perspectives. Experimental results on the DNS Challenge 2021 dataset demonstrate that CSMamba outperforms several state-of-the-art (SOTA) speech enhancement methods in three objective evaluation metrics with fewer parameters. Copyright © 2025, The Authors. All rights reserved.

关键词： Speech enhancement

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Improving Speech Enhancement by Cross- and Sub-band Processing with State Space Model

Improving Speech Enhancement by Cross- and Sub-band Processi...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Jizhen Li Weiping Tu Yuhong Yang Xinmeng Xu Yiqun Zhang Yanzhen Ren NERCMS School of Computer Science Hubei Luojia Laboratory Wuhan University China Hubei Key Laboratory of Multimedia and Network Communication Engineering Wuhan University China School of Cyber Science and Engineering Wuhan University China

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Recently, the state space model (SSM) represented by Mamba has shown remarkable performance in long-term sequence modeling tasks, including speech enhancement. However, due to substantial differences in sub-band features, applying the same SSM to all sub-bands limits its inference capability. Additionally, when processing each time frame of the time-frequency representation, the SSM may forget certain high-frequency information of low energy, making the restoration of structure in the high-frequency bands challenging. For this reason, we propose Cross- and Sub-band Mamba (CSMamba). To assist the SSM in handling different sub-band features flexibly, we propose a band split block that splits the full-band into four sub-bands with different widths based on their information similarity. We then allocate independent weights to each sub-band, thereby reducing the inference burden on the SSM. Furthermore, to mitigate the forgetting of low-energy information in the high-frequency bands by the SSM, we introduce a spectrum restoration block that enhances the representation of the cross-band features from multiple perspectives. Experimental results on the DNS Challenge 2021 dataset demonstrate that CSMamba outperforms several state-of-the-art (SOTA) speech enhancement methods in three objective evaluation metrics with fewer parameters.

关键词： Measurement Time-frequency analysis Speech enhancement Signal processing Acoustics

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Coexisting RIS Induced Multipath Fading in High-Speed Train Systems

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IEEE Transactions on Vehicular technology 2025年

作者： Wu, Wei Wang, Wennai Song, Rongfang Nanjing University of Posts and Telecommunications Key Laboratory of Broadband Wireless Communication and Sensor Network Technology Ministry of Education College of Telecommunication and Information Engineering Nanjing210003 China

Reconfigurable Intelligent Surfaces (RIS) have recently emerged as a promising and cost-effective technology for enabling stable and reliable communications in high-speed train (HST) environments. However, the coexistence of multiple RIS-assisted networks in confined train environments poses significant theoretical and practical challenges. This study focuses on the RIS coexistence problem in HST systems, specifically investigating the impact of multipath fading induced by coexisting RIS (C-RIS) on interfered users. First, we develop a simplified mutual-coupling channel model for C-RIS-induced multipath (CR-MP), applicable to operational frequency bands above 5 GHz. Second, we evaluate the effects of CR-MP on interfered users using the multipath power ratio (MPR), defined as the ratio of the received signal power to the desired signal power. The MPR formulation is derived as a function of the user's spatial position, operational frequency, and penetration loss. Finally, we analyze the spatial and temporal characteristics of the CR-MP channel through the MPR radiation pattern and the received signal envelope, respectively. Simulation results reveal that the spatial characteristics are time-varying and strongly influenced by the frequency difference and penetration loss, while the temporal characteristics depend on the user's position. When the target user is located in specific positions, the fading effects induced by CR-MP can be negligible with a reduced frequency difference, while the received signal power gain can be significantly enhanced with an increased frequency difference. The findings of this study provide practical insights for RIS deployment in real-world systems, particularly for mitigating C-RIS-induced interference in coexisting RIS-assisted networks. © 1967-2012 IEEE.

关键词： Light rail transit

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Attention Weighting and Conditional Entropy-driven Quantization Loss for Neural Audio Codecs

Attention Weighting and Conditional Entropy-driven Quantizat...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Huiyu Zhang Weiping Tu Yuhong Yang Xinmeng Xu Yanzhen Ren Rong Zhu NERCMS School of Computer Science Hubei Luojia Laboratory Wuhan University China Hubei Key Laboratory of Multimedia and Network Communication Engineering Wuhan University China School of Cyber Science and Engineering Wuhan University China

ISBN: (数字)9798350368741

ISBN: (纸本)9798350368758

Existing end-to-end neural codecs have made great progress in preserving audio quality. Despite their success, they still face challenges in achieving accurate and efficient quantization. Specifically, these codecs often overlook which features have a greater impact on perceptual audio quality during quantization, leading to a quantization error distribution that fails to reflect the actual importance of latent features. They are also sensitive to unusual data points (outliers) because they use Mean Squared Error (MSE) to measure quantization errors, which can increase quantization noise or spectral artifacts. To address these limitations, we propose AW-CEQCodec which integrates an Attention Weighting (AW) module and a Conditional Entropy-driven Quantization (CEQ) loss. The AW enhances key regions of latent features before quantization, enabling more accurate quantizing critical features and reducing their quantization errors. After quantization, it restores global details from dequantized features, improving overall reconstruction. Moreover, the CEQ minimizes the uncertainty between latent and quantized features, effectively reflecting the distortion introduced by the quantization module. Experimental results on the CodecSuperb-STL dataset demonstrate that our method consistently outperforms baseline approaches, achieving superior audio quality at bitrates as low as 0.5 kbps, confirming its effectiveness in minimizing distortion and preserving perceptual quality. The reconstruction audio samples can be find at https://***/first-page.

关键词： Quantization (signal) Codecs Acoustic distortion Accuracy Uncertainty Speech coding Real-time systems Noise measurement Speech processing Signal to noise ratio

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Joint Client Association and Resource Utilizing for Energy-Efficient Semi-Decentralized Federated Learning with Non-IID Data

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IEEE Transactions on Wireless communications 2025年

作者： Zheng, Jiali Yu, Siyi Zhao, Shulin Guangxi University Guangxi Key Laboratory of Multimedia Communications and Network Technology School of Computer Electronics and Information Guangxi Nanning 530004 China

Federated learning (FL), a distributed learning paradigm, has gained widespread application in wireless Internet of Things (IoT) scenarios. To accelerate the convergence of the global model, it is expected to allow more users to participate in the federation for training. However, in heterogeneous scenarios, unrestricted expansion of the FL scale, on the contrary, may reduce the training speed of the FL or even lead to the failure of the model convergence. In this paper, we explore the heterogeneity in wireless networks and propose a semi-decentralized FL architecture that includes a cluster head (CH) selection scheme, as well as resource allocation scheme and device matching method. The selection of the CH is constrained by the minimum overlapping clusters and limited radio resource blocks (RRBs). Additionally, in the resource and device allocation scheme, we reduce overall energy consumption under time constraints while ensuring FL model performance in non-IID environments. To achieve this, we propose a joint optimization problem considering IoT device scheduling and computation frequency allocation. Furthermore, this paper analyzes the low resource efficiency caused by stragglers and proposes a suboptimal solution with lower computational complexity for large-scale applications. Comparisons with several benchmark schemes confirm that our proposed algorithm outperforms them in terms of energy efficiency, model performance, and system stability. © 2002-2012 IEEE.

关键词： non-IID Resource Management and Allocation Semi-Decentralized FL Wireless IoT networks

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Mixed Data Augmentation Through the Integration of Mode Decomposition and Time-Series Transformation for Radio Signal Classification

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IEEE Transactions on Cognitive communications and networking 2025年

作者： Wang, Bin Yuan, Zhuang Lu, Jun Zhang, Xianchao Xi'an University of Science and Technology School of Communication Engineering Xi'an710699 China Xi'an Key Laboratory of Heterogeneous Network Convergence Communication Xi'an710054 China Jiaxing University Key Laboratory of Multimodal Sensing and Intelligent Systems of Zhejiang Province Jiaxing314001 China Key Laboratory of Medical Electronics and Digital Health of Zhejiang Province Jiaxing314001 China

The rapid development of deep learning has provided new solutions for radio signal recognition in complex electromagnetic environments, demonstrating excellent performance and being widely applied. The data-driven based radio signal recognition methods rely on large amounts of labeled data for training. However, in non-cooperative communication scenarios, the limited availability of labeled samples can lead to model overfitting, which in turn degrades the recognition performance of the model. Therefore, this paper first combines the variational mode decomposition with time series transformation to propose a mixed data augmentation method for improving the feature extraction efficiency of the model. Secondly, considering the implementation of lightweight network structures on devices with limited computing power and storage while ensuring model recognition performance, a sparse residual network (SRNet) is designed based on a hybrid attention mechanism and sparse coding structure. Finally, comparative experiments and performance analysis are conducted on simulated and real-measured data. The simulation and experiment results indicate that the proposed method can significantly improve recognition accuracy while achieving model lightweighting. © 2015 IEEE.

关键词： Cooperative communication

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Managing high heat flux electronics of over 600 W/cm2 by capillary evaporation in bi-porous wicks

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Applied Thermal Engineering 2025年 274卷

作者： Yang, Xiaoping Wang, Haolei Bu, Shichao Zhang, Yonghai Sun, Zhen Liu, Fan Wei, Jinjia School of Chemical Engineering and Technology Xi'an Jiaotong University Shaanxi Xi'an710049 China State Key Laboratory of Mobile Network and Mobile Multimedia Technology ZTE Corporation hillsides China State Key Laboratory of Fluorine & Nitrogen Chemicals School of Chemical Engineering and Technology Xi'an Jiaotong University Shaanxi Xi'an710049 China

In this work, uniform porous wicks and bi-porous wicks with a thickness of 1 mm are prepared. Additionally, deionized water serves as a working fluid, and the effects of factors such as the particle size (10 ∼ 200 μm), the content of a pore-forming agent (0 ∼ 20 wt%), and the subcooling degree (0 K and 40 K) on capillary evaporation are studied. The results show that for uniform porous wicks, as the particle diameter increases, the critical heat flux (CHF) gradually increases. For bi-porous wicks, the addition of the pore-forming agent reduces the flow resistance of liquid, and increases the space for vapor escape, thereby significantly improving the heat transfer performance by capillary evaporation. When the particle diameter is 200 μm and the content of the pore-forming agent is 20 wt% under subcooled conditions, the CHF reaches up to 621.5 W/cm2, the average thermal resistance falls to 0.06 K/W, and the evaporation heat transfer coefficient (HTC) increases to 1.6 × 105 W/(m2·K). In contrast to the uniform porous wick with the particle size of 10 μm, the CHF is increased by 46.5 %, the average thermal resistance decreases by 50 %, and the evaporation HTC increases by 400 %. Moreover, a critical heat flux of 573 W/cm2 can be achieved while maintaining a wall superheat of 38°C under saturated conditions. Additionally, as the copper powder particle diameter becomes smaller, heat transfer by the addition of the pore-forming agent is further improved. Finally, based on the conservation of energy and mass, a theoretical model for predicting the CHF of both uniform porous and bi-porous wicks is proposed, with the predicting error of within ± 20 %. This article can provide fundamental data and theoretical support for the design of high heat flux passive phase-change cooling devices. © 2025

关键词： Deionized water

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