大规模MIMO系统中基于DFT信道估计的导频污染消除方案

在大规模MIMO系统中,当基站不存在协作时,随着基站天线数的无限增加,快衰落效应和非相关噪声都能被平均掉,导频污染成为制约大规模MIMO系统性能的瓶颈。基于此,本文提出了一种基于离散傅立叶变换(DFT)信道估计的导频污染消除方法,在时域信道冲击响应中通过DFT和IDFT变换把有用的信号长度之外的污染信号当成一个样本,利用有用信号之外的污染信号样本生成一个阀值,通过引入这个预设的判决阀值,筛选出有效的信道冲击响应,消除导频污染造成的干扰。改善了信道估计的性能。仿真结果表明,在大规模MIMO系统的信道环境下,本文提出的方法可以进一步提高信道估计的精度,提高大规模MIMO的性能。

A DFT-based Channel Estimation Method against Pilot Contamination for the Massive MIMO Systems

In the Massive multiple input multiple output (MIMO)multiple cell system,with the number of base station antennas increasing, uncorrelated noise and fast fading effects can be averaged out in noncooperative base stations , Pilot contamination has become a bottleneck restricting the performance of the Massive MIMO system. In this paper, an improved discrete Fourier transform (DFT) algorithm based channel estimation for pilot decontamination is proposed. Taking useful signal channel impulse response beyond the length of informative channel taps as a interference sample in the time domain by the DFT and IDFT transform,then using the interference signal samples to generate a threshold. Then we apply the predetermined threshold screening of an effective channel impulse response to remove pilot contamination further and enhance channel estimation performance. Simulation results demonstrate the proposed algorithm can improve the accuracy of channel estimation and improve Massive MIMO system capacity.