导频序列在不同小区中不可避免地被复用, 从而产生了导频污染, 导频污染带来的干扰不会随着基站天线数的增加而减少。导频污染已成为限制大规模多输入多输出(MIMO)系统性能的主要原因之一, 为了减少导频污染带来的影响, 文章提出了时移联合空间划分的导频分配方案, 该方案通过从时间域和空间域两个方面来减少导频序列的复用次数, 从而减少导频污染。推导出了采用该方案时系统中目标上行用户的可达和速率和信干噪比(SINR)。仿真结果表明, 所提方案能有效减少导频污染, 获得较好的系统性能, 提高系统吞吐量。

Pilot sequences are inevitably multiplexed in different cells, resulting in pilot pollutions. The interference caused by pilot pollution does not decrease as the number of base station antennas increases. Pilot decontamination is one of the main reasons, which limits the performance of massive Multiple-Input Multiple-Output (MIMO) systems. To reduce the effect of pilot pollution, pilot assignment scheme with time-shift joint space partitioning is proposed, which is based on time and space domains. The pilot decontamination can be mitigated by reducing the number of reused times of the pilot sequence in two directions. We also derive the achievable uplink users access rate and Signal-Interference-Noise Ratio (SINR)in the system. The simulation results show that the proposed scheme can effectively reduce pilot pollution and improve the system performance.