大规模MIMO系统中基于导频分配策略消除导频污染算法研究

Research on pilot contamination elimination algorithm based on pilot allocation strategy in massive MIMO system

针对大规模多小区MIMO系统中导频污染是限制系统性能的主要瓶颈,提出一种基于导频分配策略降低导频污染的方法。小区内用户分配相同的导频序列,相邻小区用户分配正交的导频序列,而小区内存在的导频污染,利用下行、上行训练的方法消除。在下行训练阶段,基站给目标用户发送导频序列,使目标用户获得特殊的预失真导频序列。在上行训练阶段,基站同时接收小区内所有用户的导频序列,并消除导频污染。通过仿真分析,该方法可以完全消除导频污染的影响,获得较好的系统性能,提高系统吞吐量。更为重要的是,该方法与许多其他消除导频污染的算法相比,能避免每个基站在估计信道状态信息时已知其二阶统计信息的假设。

The pilot contamination in multi-housing-estate massive multiple-input multiple-output（MIMO） systems is a major bottleneck to limit the system performance. A method based on pilot allocation strategy to reduce the pilot contamination is proposed,whose purpose is to allocate the same pilot sequence to users within a housing-estate,and assign the orthogonal pilot sequence to the users in adjacent housing-estates. The downlink and uplink training method is used to eliminate the pilot contamination in the housing-estates. In the downlink training stage,the base station sends the pilot sequence to the target user so that the target user can obtain a special predistortion pilot sequence. In the uplink training stage, the base station simultaneously receives the pilot sequence of all the users in the housing-estate to eliminate the pilot contamination. The simulation analysis results show that the proposed algorithm can eliminate the influence of pilot contamination,obtain the perfect system performance and improve the throughout of the system,and in comparison with other pilot contamination elimination algorithms,the proposed algorithm can avoid the assumption of the known second-order statistical information when the channel state information of each base station is estimated.