Article
Telecommunications
Srishti Sharma, Swades De
Summary: In this letter, the concept of distributed optical beamforming and its feasibility requirements are proposed. The importance of polarization beamforming among the beams for maximized beamforming is quantified. The critical requirement of polarization alignment for maximized beamforming gain is demonstrated using coplanar sources and receiver. The optimal polarization angle at the sources is determined theoretically and verified through simulations such that the electromagnetic waves interfere constructively at the receiver. A novel method for automated polarization beamforming of multiple optical beams independent of source locations is proposed. The performance of the proposed distributed polarization beamforming is analytically captured and verified through simulations, showing that the reduction in gain caused by slight deviation from coplanarity is not significant.
IEEE COMMUNICATIONS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Sven O. Petersson, Maksym A. Girnyk
Summary: Massive MIMO is a promising technology for 5G wireless communications, which enables user-specific transmission through beamforming. However, research on using broad beams for public-channel transmission is limited. This paper introduces the concept of array-size invariant (ASI) beamforming, which generates broad beams from large antenna arrays, and demonstrates the advantages of this technique through numerical examples.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2022)
Article
Computer Science, Information Systems
Mingyang Yue, Lei Liu, Xiaojun Yuan
Summary: Reconfigurable intelligent surface (RIS) is considered a promising technology for next-generation wireless networks to improve spectrum efficiency or energy efficiency. This letter investigates a practical RIS-aided coded system for the first time, optimizing precoding and passive beamforming to minimize transmission power given the bit error rate (BER). Utilizing alternate optimization, significant performance improvement is achieved through iterative optimization of precoding and passive beamforming.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2021)
Article
Engineering, Electrical & Electronic
Hanyu Wang, Jun Fang, Peilan Wang, Guangrong Yue, Hongbin Li
Summary: This article investigates the problem of downlink beamforming training and channel estimation for millimeter wave OFDM systems, proposing a sparse bipartite graph code-based algorithm that utilizes sparse encoding and signal recovery for efficient channel estimation. The theoretical analysis demonstrates the reduction in training overhead achieved by the proposed method, with simulations showing its effectiveness and performance advantages over compressed sensing-based methods.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2021)
Article
Engineering, Electrical & Electronic
Alexander J. Mackay, George V. Eleftheriades
Summary: Peripherally excited (PEX) phased arrays can achieve various shaped beams by controlling the magnitude and phase of the antenna's peripheral sources, offering a simple and cost-effective solution. A linear system of equations is developed using a simple model of fields in a parallel-plate waveguide to find the best peripheral source excitations that approximate a desired field pattern. The model successfully synthesizes uniform broadside beams and cosecant beams with higher aperture illumination efficiency than equal-amplitude excitation. The linear system can be integrated with particle swarm optimization (PSO) for controlled sidelobe levels, flat-top, and multibeam patterns, demonstrating good agreement with ideal and predicted beams in full-wave simulation.
IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION
(2023)
Article
Materials Science, Multidisciplinary
Yan Teng, Chun Li, Shaochen Li, Yuan Ren, Ling Jiang
Summary: The study presents two types of quad-beam splitters (QBS) based on coding metamaterials, with the 2 x 2 QBS showing higher power efficiency and broader bandwidth compared to the 1 x 4 QBS when tested with normally incident electromagnetic waves.
Article
Computer Science, Information Systems
Kandasamy Pirapaharan, Nagananthakumaran Ajithkumar, Konesamoorthy Sarujan, Xavier Fernando, Paul R. P. Hoole
Summary: Smart Antennas are crucial for providing mobility support in enhanced wireless applications like 5G and future technologies. They help decrease interference and multipath problems, enhancing signal quality. This paper presents different nonlinear configurations for forming a single beam in any desired direction. The proposed array structures with multiple axes of symmetry reduce computational repetitions and optimize beam-steering functionality. The performance of different array configurations is compared based on directivity, sidelobe reduction, and computational complexities.
Article
Engineering, Electrical & Electronic
Yinghui He, Yunlong Cai, Hao Mao, Guanding Yu
Summary: This paper proposes a double-reconfigurable intelligent surface (RIS)-assisted coexistence system to enhance communication signals and suppress mutual interference. The beamforming optimization problem is transformed into a tractable form by introducing auxiliary variables, and a penalty dual decomposition (PDD)-based algorithm is proposed. Special cases of large radar transmit power and low radar transmit power are also considered, and respective optimization methods are applied. Simulation results demonstrate the superiority of the proposed algorithms over benchmark algorithms.
IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Xufang Wang, Zihuai Lin, Feng Lin, Lajos Hanzo
Summary: This study proposes a joint hybrid beamformer for Terahertz (THz) multi-user Massive MIMO systems aided by Reconfigurable Intelligent Surfaces (RIS). The system utilizes high-gain beamforming to counteract the high pathloss associated with THz systems. The proposed system includes a novel architecture for the base station and the corresponding sub-RIS, and integrates Ultra-wideband (UWB) sensors for channel estimation. The system also improves beamforming accuracy through a Precise Beamforming Algorithm (PBA) that accounts for positioning errors. Simulation results demonstrate a significant improvement in spectral efficiency compared to existing schemes.
IEEE SENSORS JOURNAL
(2022)
Article
Engineering, Electrical & Electronic
Marco Ferrari, Fardad Vakilipoor, Eric Regonesi, Mariangela Rapisarda, Maurizio Magarini
Summary: This paper presents an analytical model for describing the impulse response of the diffusive channel in a molecular communication system. The model takes into account the influence of neighboring interferers on the channel impulse response and solves the integral equation system numerically.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2022)
Article
Geochemistry & Geophysics
Tie Li, Jianhu Zhao
Summary: The article introduces an algorithm called Cross for faster and more accurate acquisition of the spatial incidence angle of multibeam echosounders, which is a generic method regardless of shallow or deep water.
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
(2022)
Article
Computer Science, Information Systems
Dingyan Cong, Shuaishuai Guo, Haixia Zhang, Jia Ye, Mohamed-Slim Alouini
Summary: Joint beamforming for integrated sensing and communication (ISAC) is proposed in this letter to combine two functionalities at the waveform level. The beamforming design for ISAC systems with finite alphabet signaling is formulated as an optimization problem, which is solved through a semi-definite relaxation (SDR) method. Comprehensive comparisons show that our proposed beamforming offers better performance in symbol error rate (SER), mutual information, and sensing performance compared to existing ISAC beamforming designs.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2022)
Article
Computer Science, Hardware & Architecture
Xianfu Lei, Mingjiang Wu, Fuhui Zhou, Xiaohu Tang, Rose Qingyang Hu, Pingzhi Fan
Summary: This article provides a comprehensive review of the RIS-based SR system, including its technical advantages, application scenarios, and a proposed modulation scheme to enhance performance. The content covers system architectures, operating principles, performance simulations, and future research directions for implementing RIS-based SR.
IEEE WIRELESS COMMUNICATIONS
(2021)
Article
Optics
Bing Wang, Weidong Hu, Haidong Qiao, Zhihao Xu, Huanyu Jiang, Xiong Xiao, Leo p. Ligthart
Summary: This paper presents a 170 GHz quasi-optical sub-harmonic mixer with a 3D-printed back-to-back lenses packaging. The mixer employs a pair of antiparallel GaAs Schottky diodes, which provide good radiation gain and mechanical robustness. The compact matching network ensures efficient signal coupling and signal isolation. The measured results agree well with the simulated results.
Article
Computer Science, Information Systems
Fan Yang, Yuhan Dong
Summary: We propose a joint probabilistic shaping and beamforming scheme to approach the channel capacity of MISO VLC systems subject to power constraints. An iterative algorithm is used to obtain the optimal constellation distribution and beamforming vector. Numerical results show that the proposed scheme outperforms the conventional uniformly distributed PAM scheme.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2022)
Article
Engineering, Electrical & Electronic
Yuhang Chen, Longfei Yan, Chong Han, Meixia Tao
Summary: Terahertz wireless communications aim to achieve data rates of over 100 Gbps for 6G communications using UM-MIMO systems and DAoSA beamforming technology. Challenges include precise DoA estimation, beam tracking, and reducing pilot overhead.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Weijun Gao, Chong Han, Zhi Chen
Summary: This paper proposes a deep neural network (DNN)-based mechanism for secure THz communications, which uses artificial noise (AN) to assist in receiver design with self-interference cancellation (SIC) elimination, addressing the security challenge posed by eavesdroppers within the beam radiation sector. The numerical results demonstrate that this mechanism significantly improves the secrecy rate and reduces the secrecy outage probability when eavesdroppers are in close proximity.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Hang Yuan, Nan Yang, Xuhui Ding, Chong Han, Kai Yang, Jianping An
Summary: This paper proposes a cluster-based multi-carrier beam division multiple access scheme combined with a dynamic-subarray hybrid beamforming architecture for massive device terahertz communications. By exploiting the properties of THz channels, the proposed scheme improves the spectral and energy efficiency of the system.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2022)
Article
Engineering, Electrical & Electronic
Yongzhi Wu, Filip Lemic, Chong Han, Zhi Chen
Summary: In this work, a sensing integrated discrete Fourier transform spread orthogonal frequency division multiplexing (SI-DFT-s-OFDM) system is proposed for THz ISAC, which can provide lower peak-to-average power ratio than OFDM and is adaptive to flexible delay spread of the THz channel. A deep learning based ISAC receiver with two neural networks is developed to recover transmitted data and estimate target range and velocity, while mitigating the imperfections and non-linearities of THz systems. Extensive simulation results demonstrate that the proposed deep learning methods can realize mutually enhanced performance for communication and sensing, and is robust against Doppler effects, phase noise and multi-target estimation.
IEEE TRANSACTIONS ON COMMUNICATIONS
(2023)
Article
Computer Science, Information Systems
Yuxin Xie, Boyu Ning, Lingxiang Li, Zhi Chen
Summary: In this letter, we propose a method to use the uniform circular array (UCA) for beam training in Terahertz near-field communications, and design a codebook specifically for near-field communications. The UCA shows advantages in reducing the codebook size compared to the conventional uniform linear array (ULA). Numerical results validate the effectiveness of the proposed beam-shape model and demonstrate the merits of our near-field codebook of UCA.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Computer Science, Information Systems
Mengbing Liu, Xin Li, Boyu Ning, Chongwen Huang, Sumei Sun, Chau Yuen
Summary: In this letter, the estimation of cascaded channels in a double-RIS aided massive MIMO system is investigated. To address this challenge, a skip-connection attention network is proposed to improve the channel estimation performance by utilizing self-attention layers and skip-connection structure.
IEEE WIRELESS COMMUNICATIONS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Yuanbo Li, Yi Chen, Dong Yan, Ke Guan, Chong Han
Summary: To support intelligent vehicular services, high-speed communications from vehicles to infrastructure (V2I) are needed in vehicular ad-hoc networks (VANET). The Terahertz (THz) band, which has abundant spectrum resources, is considered promising for this purpose. However, channel modeling for THz V2I communications is a challenge. In this paper, ray-tracing techniques are used to analyze the V2I channel at 300 GHz in an urban scenario, and a novel ray-tracing assisted stochastic channel model (RTA-SCM) is proposed.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Sha Xie, Lingxiang Li, Zhi Chen, Boyu Ning, Weixin Chen, Shaoqian Li
Summary: This paper investigates the improvement of THz transmission distance through mobile computing by reducing the data transmission rate requirement. The proposed algorithms are shown to effectively improve THz transmission distance.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Renwang Li, Shu Sun, Yuhang Chen, Chong Han, Meixia Tao
Summary: Reconfigurable intelligent surfaces (RISs) are a prospective technology for next-generation wireless networks, offering potential in coverage and capacity enhancement. This study focuses on the achievable rate of RIS-assisted multiple-input multiple-output communication systems in the millimeter-wave band with limited scattering. An upper bound of the achievable rate is derived using majorization theory and Jensen's inequality, and optimization algorithms are proposed to maximize the achievable rate. Simulation results validate the effectiveness of the proposed algorithms.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Engineering, Electrical & Electronic
Longfei Yan, Chong Han, Nan Yang, Jinhong Yuan
Summary: In this paper, an energy-efficient dynamic-subarray with fixed phase shifters (DS-FPS) architecture is proposed for terahertz hybrid beamforming, which compensates for the spectral efficiency loss caused by the fixed phase of FPS through a switch network and designs the hybrid beamforming matrices using a row-successive-decomposition (RSD) algorithm. A row-by-row (RBR) algorithm is further proposed to reduce computational complexity. Extensive simulation results show that the proposed DS-FPS architecture with the RSD and RBR algorithms achieves higher energy efficiency and robustness to CSI error compared to existing architectures.
IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS
(2023)
Article
Mathematics
Yue Huang, Lijuan Sun, Chong Han, Jian Guo
Summary: By using raw legal judgments as information and proposing a two-stage text-summarization model to handle different granularities of information, this study effectively captured essential and relevant information from lengthy legal texts and generated better legal judgment summaries. The model achieved an overall 0.19-0.41 improvement in its ROUGE score compared to the baseline models, demonstrating its effectiveness.
Article
Engineering, Electrical & Electronic
Huan Huang, Chongfu Zhang, Ying Zhang, Boyu Ning, Hao Gao, Songnian Fu, Kun Qiu, Zhu Han
Summary: In this study, we propose a solution to the downlink precoding problem in the RIS-aided mmWave MU-MISO system. By employing codebook-based passive beamforming and analog beamforming to reduce channel estimation overheads, and designing a two-timescale-based beam training algorithm to further reduce training overheads, we achieve better performance and lower overheads compared to existing algorithms.
IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY
(2023)
Article
Engineering, Electrical & Electronic
Boyu Ning, Zhongbao Tian, Weidong Mei, Zhi Chen, Chong Han, Shaoqian Li, Jinhong Yuan, Rui Zhang
Summary: This paper provides a review of beamforming technologies for terahertz ultra-massive multiple-input-multiple-output (UM-MIMO) systems. It presents the system model, channel parameters, and discusses the far-field and near-field assumptions in terahertz UM-MIMO. The beam training strategy in terahertz band is introduced, along with codebook design approaches. The paper also explores intelligent-reflecting-surface (IRS)-assisted joint beamforming and multi-user beamforming in terahertz UM-MIMO systems.
IEEE OPEN JOURNAL OF THE COMMUNICATIONS SOCIETY
(2023)
