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Joint Beamforming for Intelligent Reflecting Surface Aided Wireless Communication Using Statistical CSI

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China Communications 2020年第8期17卷 147-157页

作者： Jian Dang zaichen zhang Liang Wu National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China

A joint beamforming algorithm is proposed for intelligent reflecting surface(IRS) aided wireless multiple-input multiple-output(MIMO) communication using statistical channel state information(CSI). The beamforming is done by alternatively optimizing the IRS reflecting coefficients and the covariance matrix of the transmit symbol vector, such that the ergodic rate of the system is maximized. The algorithm utilizes only the second order momentum of the random channel matrices and does assume any specific channel distribution, leading to a general framework for ergodic rate evaluation. A practical channel correlation model is configured to validate the performance gain. It is found that the rate can be enlarged by the joint optimization algorithm, however, the gain over that of randomly deployed reflecting coefficients depends highly on the relative correlation distance of the IRS elements and the spatial position of the IRS. In particular, the results suggest that IRS should be placed in the vicinity of either the transmitter or the receiver. Placing IRS far away from those positions is non-beneficial.

关键词： MIMO beamforming statistical CSI intelligent reflecting surface(IRS) ergodic rate

Upper bounds on the capacity for optical intensity channels with AWGN

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Science China(Information Sciences) 2017年第2期60卷 165-176页

作者： Yingying YU zaichen zhang Liang WU Jian DANG National Mobile Communications Research Laboratory Southeast University

The channel capacity of the optical wireless communication(OWC) systems is still a problem that has not an optimal and close-form expression, in spite of OWC can be used to achieve high data rates. This paper presents novel upper bounds on the channel capacity of an optical intensity modulated and directed detection(IM/DD) system under peak-power and average-power constraints. The channel is modeled as an additive white Gaussian noise(AWGN) optical channel. The bounds are derived based on sphere-based signal space argument. Simulation results show the proposed bounds are tight at both high and low signal-to-noise ratios(SNRs). Compared to those reported bounds, the derived bounds are better at high SNRs region in particular, and the expressions are simpler and unique for the whole range of average-to-peak-power ratio.

关键词： channel capacity optical communication AWGN sphere-based signal space high signal-to-noise ratios(SNRs)

Efficient stochastic successive cancellation list decoder for polar codes

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Science China(Information Sciences) 2020年第10期63卷 133-151页

作者： Xiao LIANG Huizheng WANG Yifei SHEN zaichen zhang Xiaohu YOU Chuan zhang Laboratory of Efficient Architectures for Digital-communication and Signal-processing (LEADS) Southeast University National Mobile Communications Research Laboratory Southeast University Quantum Information Center of Southeast University

Polar codes are one of the most favorable capacity-achieving codes owing to their simple structures and low decoding complexity. Successive cancellation list(SCL) decoders with large list sizes achieve performances very close to those of maximum-likelihood(ML) decoders. However, hardware cost is a severe problem because an SCL decoder with list size L consists of L copies of a successive cancellation(SC)decoder. To address this issue, a stochastic SCL(SSCL) polar decoder is proposed. Although stochastic computing can achieve a good hardware reduction compared with the deterministic one, its straightforward application to an SCL decoder is not well-suited owing to the precision loss and severe latency. Therefore,a doubling probability approach and adaptive distributed sorting(DS) are introduced. A corresponding hardware architecture is also developed. Field programmable gate array(FPGA) results demonstrate that the proposed stochastic SCL polar decoder can achieve a good performance and complexity tradeoff.

关键词： SCL polar decoder stochastic computing 2-bit decoding distributed sorting hardware

竖转法在超大悬挑巨型带肋空间折板网格结构安装中的应用

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建筑结构 2024年第14期54卷 47-52页

作者：贾新卷张在晨莫海钊赵绪华中国建筑第四工程局有限公司广州510665

广州新足球场是计划建设的国际顶级场馆,其钢罩棚最高点标高88.6m,悬挑最长91m,网格尺寸最大64m,为国内罕见的巨型带肋空间折板网格结构。基于项目钢罩棚的特点,创新性地引入桥梁竖转法思路,结合数值计算对竖转单元分组、竖转路径选择... 详细信息

广州新足球场是计划建设的国际顶级场馆,其钢罩棚最高点标高88.6m,悬挑最长91m,网格尺寸最大64m,为国内罕见的巨型带肋空间折板网格结构。基于项目钢罩棚的特点,创新性地引入桥梁竖转法思路,结合数值计算对竖转单元分组、竖转路径选择、提升架布置等核心技术问题进行深入剖析,并对竖转施工中关键工序的变形及内力进行分析,以全面验证方案的可实施性。结果表明:针对巨型带肋空间折板网格结构,采用三榀分组,将转铰布置于上拉力环杆件节点连接处,并设置提升架于场心的整体方案是可行的。相较于传统安装方法,竖转法在施工质量、安全、工期、造价等方面均有一定的优势,具有较好的推广价值。

关键词：广州新足球场竖转法空间折板网格结构超大悬挑钢结构安装

Enhanced Power Choice Barring Scheme For Massive MTCs With Grant-Free NOMA

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China Communications 2021年第10期18卷 135-147页

作者： Liang Wu Xiaorui Tang zaichen zhang Jian Dang National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China

Massive machine-type communication(m MTC)is a typical application scenario of the fifth generation(5G)mobile *** keep the m MTC reliable and minimize the energy consumption of the m MTC devices,this paper proposes an enhanced power choice barring(EPCB)scheme based on the distributed layered grant-free non-orthogonal multiple access(NOMA)framework,where the cell is divided into different layers according to a predetermined power *** proposed EPCB scheme not only combines the grant-free strategy with the sleep mode to reduce the energy consumption,but also designs a power level choosing strategy to increase the access success *** results show that when compared with existing schemes,the proposed EPCB scheme has better performance in the aspects of the access success probability and energy efficiency.

关键词： grant-free massive machine-type communication NOMA power level choosing

Vector Approximate Message Passing with Sparse Bayesian Learning for Gaussian Mixture Prior

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China Communications 2023年第5期20卷 57-69页

作者： Chengyao Ruan zaichen zhang Hao Jiang Jian Dang Liang Wu Hongming zhang National Mobile Communications Research Laboratory Frontiers Science Center for Mobile Information Communication and SecuritySoutheast UniversityNanjing 210096China Purple Mountain Laboratories No.9 Mozhou East RoadNanjing 211111China School of Artificial Intelligence Nanjing University of Information Science and TechnologyNanjing 210044China School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear ***,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate message passing(AMP)based algorithms have been *** SBL,it has accurate performance with robustness while its computational complexity is high due to matrix *** AMP,its performance is guaranteed by the severe restriction of the measurement matrix,which limits its application in solving CS *** overcome the drawbacks of the above algorithms,in this paper,we present a low complexity algorithm for the single linear model that incorporates the vector AMP(VAMP)into the SBL structure with expectation maximization(EM).Specifically,we apply the variance auto-tuning into the VAMP to implement the E step in SBL,which decrease the iterations that require to converge compared with VAMP-EM algorithm when using a Gaussian mixture(GM)*** results show that the proposed algorithm has better performance with high robustness under various cases of difficult measurement matrices.

关键词： sparse Bayesian learning approximate message passing compressed sensing expectation propagation

Acquisition of channel state information for mmWave massive MIMO: traditional and machine learning-based approaches

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Science China(Information Sciences) 2021年第8期64卷 5-20页

作者： Chenhao QI Peihao DONG Wenyan MA Hua zhang zaichen zhang Geoffrey Ye LI School of Information Science and Engineering Southeast University College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics Department of Electrical and Electronic Engineering Imperial College London

The accuracy of channel state information(CSI) acquisition directly affects the performance of millimeter wave(mmWave) communications. In this article, we provide an overview on CSI acquisition,including beam training and channel estimation for mmWave massive multiple-input multiple-output *** beam training can avoid the estimation of a high-dimension channel matrix, while the channel estimation can flexibly exploit advanced signal processing techniques. In addition to introducing the traditional and machine learning-based approaches in this article, we also compare different approaches in terms of spectral efficiency, computational complexity, and overhead.

关键词： beam training channel estimation machine learning massive MIMO millimeter wave (mmWave) communications

DNA computing for combinational logic

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Science China(Information Sciences) 2019年第6期62卷 5-20页

作者： Chuan zhang Lulu GE Yuchen ZHUANG Ziyuan SHEN Zhiwei ZHONG zaichen zhang Xiaohu YOU Lab of Efficient Architectures for Digital-communication and Signal-processing (LEADS) Southeast University National Mobile Communications Research Laboratory Southeast University Quantum Information Center Southeast University

With the progressive scale-down of semiconductor’s feature size, people are looking forward to More Moore and More than Moore. In order to o?er a possible alternative implementation process,researchers are trying to figure out a feasible transfer from silicon to molecular computing. Such transfer lies on bio-based modules programming with computer-like logic, aiming at realizing the Turing *** accomplish this, the DNA-based combinational logic is inevitably the first step we have taken care *** timely overview study introduces combinational logic synthesized in DNA computing from both analog and digital perspectives separately. State-of-the-art research progress is summarized for interested readers to quick understand DNA computing, initiate discussion on existing techniques and inspire innovation *** hope this study can pave the way for the future DNA computing synthesis.

关键词： synthetic biology DNA computing DNA strand displacement reactions chemical reaction networks combinational logic

Polar-coded forward error correction for MLC NAND flash memory

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Science China(Information Sciences) 2018年第10期61卷 224-239页

作者： Haochuan SONG Jen-Chien FU Shih-Jia ZENG Jin SHA zaichen zhang Xiaohu YOU Chuan zhang Lab of Efficient Architectures for Digital-communication(LEADS) National Mobile Communications Research Laboratory Southeast University Quantum Information Center of Southeast University National Mobile Communications Research Laboratory Southeast University Lite-On Technology Corporation School of Electronic Science and Engineering Nanjing University

With the ever-growing storage density, high-speed, and low-cost data access, flash memory has inevitably become popular. Multi-level cell(MLC) NAND flash memory, which can well balance the data density and memory stability, has occupied the largest market share of flash memory. With the aggressive memory scaling, however, the reliability decays sharply owing to multiple interferences. Therefore, the control system should be embedded with a suitable error correction code(ECC) to guarantee the data integrity and accuracy. We proposed the pre-check scheme which is a multi-strategy polar code scheme to strike a balance between reasonable frame error rate(FER) and decoding latency. Three decoders namely binaryinput, quantized-soft, and pure-soft decoders are embedded in this scheme. Since the calculation of soft loglikelihood ratio(LLR) inputs needs multiple sensing operations and optional quantization boundaries, a 2-bit quantized hard-decision decoder is proposed to outperform the hard-decoded LDPC bit-flipping decoder with fewer sensing operations. We notice that polar codes have much lower computational complexity compared with LDPC codes. The stepwise maximum mutual information(SMMI) scheme is also proposed to obtain overlapped boundaries without exhausting search. The mapping scheme using Gray code is employed and proved to achieve better raw error performance compared with other alternatives. Hardware architectures are also given in this paper.

关键词： polar coding non-volatile memory error correcting code NAND flash memory