High-speed train (HST) communications with orthogonal frequency division multiplexing (OFDM) techniques have received significant attention in recent years. Besides, cell-free (CF) massive multiple-input multiple-output (MIMO) is considered a promising technology to achieve the ultimate performance limit. In this paper, we focus on the performance of CF massive MIMO-OFDM systems with both matched filter and large-scale fading decoding (LSFD) receivers in HST communications. HST communications with small cell and cellular massive MIMO-OFDM systems are also analyzed for comparison. Considering the bad effect of Doppler frequency offset (DFO) on system performance, exact closed-form expressions for uplink spectral efficiency (SE) of all systems are derived. According to the simulation results, we find that the CF massive MIMO-OFDM system with LSFD achieves both larger SE and lower SE drop percentages than other systems. In addition, increasing the number of access points (APs) and antennas per AP can effectively compensate for the performance loss from the DFO. Moreover, there is an optimal vertical distance between APs and HST to achieve the maximum SE.
翻译:近年来,高速列车(HST)与正心频率分解多功能(OFDM)技术的通信受到高度重视,此外,无细胞(CF)大规模多投入多产出(MIMO)被认为是实现最终性能极限的有希望的技术,在本文中,我们侧重于CF大型IMO-OFDM系统在HST通信中具有匹配过滤器和大规模脱法(LSFD)接收器的性能,对小细胞和蜂窝大型MIMO-OFDM系统的HST通信也进行了比较比较分析,考虑到多普勒频率(DFO)抵消(DFO)对系统性能的坏影响,所有系统上链光谱效率(SE)的精确封闭式表达方式都得到推导出,根据模拟结果,我们发现CFC大型IMO-OFD系统与LSFD的超大型SE和低SELDD的下降率百分比,此外,增加每个AP的接入点和天线的数量可以有效补偿DFO的性能损失。此外,AP和HST之间有最佳垂直距离。