异步通信
多输入多输出
正交性
计算机科学
电信线路
传输(电信)
光谱效率
电子工程
频道(广播)
本振子
拓扑(电路)
电信
工程类
数学
电气工程
无线电频率
几何学
作者
Jiakang Zheng,Zhuoyi Zhao,Jiayi Zhang,Julian Cheng,Victor C. M. Leung
标识
DOI:10.1109/gcwkshps56602.2022.10008786
摘要
Cell-free (CF) massive multiple-input multiple-output (MIMO) is considered as a promising technology for achieving the ultimate performance limit. However, due to its distributed architecture and low-cost access points (APs), the signals received at user equipments (UEs) are most likely asynchronous. In this paper, we investigate the performance of CF massive MIMO systems with asynchronous reception, including both effects of delay and oscillator phases. Taking into account the imperfect channel state information caused by phase asynchronization and pilot contamination, we obtain novel and closed-form downlink spectral efficiency (SE) expressions with coherent and non-coherent data transmission schemes, respectively. Simulation results show that asynchronous reception destroys the orthogonality of pilots and coherent transmission of data, and thus results in poor system performance. In addition, getting a highly accurate delay phase is substantial for CF massive MIMO systems to achieve coherent transmission gain. Moreover, the oscillator phase of UEs has a larger effect on SE than that of the APs, because the latter can be significantly reduced by increasing the number of antennas.
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