Spectral Efficiency of Superimposed Pilots in Cell-Free Massive MIMO Systems with Hardware Impairments  

作　　者：Yao Zhang Meng Zhou Haitao Zhao Longxiang Yang Hongbo Zhu 

机构地区：[1]The Department of Wireless Communication Key Lab of Jiangsu Province,Nanjing University of Posts and Telecommunications,Nanjing 210003,China

出　　处：《China Communications》2021年第6期146-161,共16页中国通信（英文版）

基　　金：This work was supported in part by the National Natural Science Foundation of China under Grants 62071246,61771252,61861039,and 61427801;in part by the National Key Research and Development Program of China under Grants 2020YFB1806608 and 2018YFC1314903;in part by the Jiangsu Province Special Fund Project for Transformation of Scientific and Technological Achievements under Grant BA2019058;in part by the Major Natural Science Research Project of Jiangsu Higher Education Institutions under Grant 18KJA510005;in part by the Postgraduate Research&Practice Innovation Program of Jiangsu Province under Grants SJKY190740 and KYCX200709.

摘　　要：In this paper,the spectral efficiency(SE)of an uplink hardware-constrained cell-free massive multi-input multi-output(MIMO)system with maximal ratio combining(MRC)receiver filters in the context of superimposed pilots(SPs)is investigated.Tractable closed-form SE expressions for the considered system are derived,which share us with opportunities to explore the impacts of the hardware quality coefficient,the length of coherence interval,and the power balance factor between pilot and data signals.Numerical results indicate that the achievable SE deteriorates as the hardware quality decreases and is more susceptible to the hardware impairments at the user equipments(UEs).Besides,we observe that SPs outperform regular pilots(RPs)in terms of SE and this performance gain is heavily dependent on the values of power balance factor and coherence interval.However,the superiorities of SPs over RPs have vanished when severe hardware imperfections are considered.

关 键 词：cell-free massive MIMO hardware impairments superimposed pilots spectral efficiency 

分 类 号：TN929.5[电子电信—通信与信息系统]