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Hybrid beamforming design for mm Wave OFDM distributed antenna systems

Science China(Information Sciences) 2020年第9期63卷 231-242+201-203页

作者： Yu ZHANG Dongming WANG Yiming HUO Xiaodai DONG Xiaohu YOU National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratory Southeast University Department of Electrical and Computer Engineering University of Victoria

This paper presents a hybrid beamforming design for millimeter-wave(mm Wave) orthogonal frequency division multiplexing(OFDM) distributed antenna systems(DASs). First, we derive a downlink signal transmission model that considers the delay spread differences(DSDs) caused by the distributed nature of the network. We then propose a cooperative wideband hybrid beamforming method under the transmitting power constraints of each remote access unit. In a simulation study, the proposed method performed comparably to fully-digital beamforming, even when operated with practical finite-resolution phase shifters. We further confirm that the DSDs are the dominant cause of performance degradation in mm Wave OFDM DASs.

关键词： hybrid beamforming distributed antenna systems millimeter wave OFDM delay spread differences synchronization

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Energy Efficiency of distributed antenna systems with D2D Communications Under Imperfect CSI

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Journal of Communications and Information Networks 2020年第1期5卷 62-74页

作者： Chunlong He Fangyan Zeng Chiya Zhang Cunhua Pan Daquan Feng Fu-Chun Zheng Guangdong Key Laboratory of Intelligent Information Processing Shenzhen 518060China School of Electronic and Information Engineering Harbin Institute of TechnologyShenzhen 518055China School of Electronic Engineering and Computer Science Queen Mary University of LondonLondon E14NSUK

In this paper,we investigate the distributed antenna systems(DAS)based on device to device(DASD2D)communications under the imperfect channel state information(CSI).Our aim is to maximize the energy efficiency(EE)of the D2D users equipment(DUE)under the constraints of the maximum transmission power of D2D pairs and the quality of service(QoS)requirements of the cellular user equipment(CUE).The worst-case design is considered so that the QoS of the CUE can be guaranteed for every realization of the CSI error in the ellipsoid *** EE objective function of the optimization problem is non-convex and non-linear,and thus this problem cannot be solved by the traditional optimization *** solve this problem,first we transform it to an EE maximization problem without uncertain parameters by exploiting the Markov and Cauchy-Schwartz *** using the fractional programming theory and difference of convex functions optimization method,the robust EE maximization algorithms based on the hard and soft protection method are developed to maximize the system’s EE performance,***,these two algorithms are designed at the cost of the reduced EE of the ***,in order to further improve the EE performance and make a trade-off between the EE performance and the robustness,the iterative update algorithms for the total power constraint and average interference constraint are developed to maximize the system’s EE performance,*** results demonstrate the effectiveness of the four proposed EE algorithms and illustrate the trade-off between the EE performance and robustness for the iterative update algorithms.

关键词： distributed antenna systems device-todevice communications energy efficiency robust worstcase power allocation imperfect channel state information

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Forward Link Performance Analysis in CDMA distributed antenna systems with Imperfect Channel Estimation

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The Journal of China Universities of Posts and Telecommunications 2005年第1期12卷 64-69页

作者： CHENPeng WUWei-ling InformationEngineeringSchool BeijingUniversityofPostsandTelecommunicationsBeijing100876P.R.China

The impact of imperfect channel estimation on the forward-link performance inCDMA distributed antenna systems in multi-path fading environment is investigated. A detailedanalytical model based on a hybrid signal combining method is presented and exact outage probabilityexpression is derived. The investigation shows that the effect of imperfect channel estimatesvaries with system load. Furthermore, if simulcasting is employed, macro-diversity can decrease thesensitivity of forward-link to channel estimation errors and increase the forward-link outageperformance, which is contrary to the conclusion drawn based on the ideal channel estimationassumption.

关键词： CDMA distributed antenna systems imperfect channel estimation outageprobability

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Cell-Free Massive MIMO for 6G Wireless Communication Networks

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Journal of Communications and Information Networks 2021年第4期6卷 321-335页

作者： Hengtao He Xianghao Yu Jun Zhang Shenghui Song Khaled B.Letaief Department of ECE Hong Kong University of Science and TechnologyHong Kong 999077China Peng Cheng Laboratory Shenzhen 518000China

The recently commercialized fifth-generation(5G)wireless networks have achieved many improvements,including air interface enhancement,spectrum expansion,and network intensification by several key technologies,such as massive multiple-input multipleoutput(MIMO),millimeter-wave communications,and ultra-dense *** the deployment of 5G commercial systems,wireless communications is still facing many challenges to enable connected intelligence and a myriad of applications such as industrial Internet-ofthings,autonomous systems,brain-computer interfaces,digital twin,tactile Internet,***,it is urgent to start research on the sixth-generation(6G)wireless communication *** the candidate technologies for 6G,cell-free massive MIMO,which combines the advantages of distributed systems and massive MIMO,is a promising solution to enhance the wireless transmission efficiency and provide better *** this paper,we present a comprehensive study on cell-free massive MIMO for 6G wireless communication networks with a special focus on the signal processing ***,we introduce enabling physical layer technologies for cell-free massive MIMO,such as user association,pilot assignment,transmitter,and receiver design,as well as power control and ***,some current and future research problems are described.

关键词： 6G network cell-free massive MIMO distributed antenna systems massive MIMO user-centric

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