导频污染被认为是多小区大规模MIMO通信系统的主要技术瓶颈,与以小区为单位进行导频复用方案不同,提出了一种减轻导频污染影响的优化的部分导频调度方案。该调度方案先将全部可用的正交导频序列划分为若干子集,把其中的一个导频子集设为导频复用子集,该导频子集在系统中每个小区复用,其余导频子集则在不相邻小区间复用;之后在目标小区基站对导频复用子集中的导频序列引起的小区间干扰进行测量,依次将导频复用子集中具有最小小区间干扰的导频序列分配给上行链路信道质量最差的用户,改善系统频谱利用率。分析和仿真结果显示该导频调度方案可以有效抑制导频污染,并且相比于目前已有的导频调度方案性能有所改进。
Pilot contamination is known to be one of the main bottleneck for massive MIMO multicell communications. Different from the existing pilot allocation schemes,a new pilot allocation scheme is proposed to restrain the pilot contamination. The key idea is to a fraction of users within each cell reuse the same pilot subset across the whole system,in which the base station firstly measures the inter-cell interference of each pilot sequence of the reuse subset. Then,the propose scheme assigns the pilot sequence with minimum inter-cell interference to the user having the worst channel quality in a sequential way to improve its performance. While the rest of users reuse the orthogonal subset among the non-adjacent cells. Analysis and numerical results show a remarkable improvement compared with the existed scheme and can restrain the pilot contamination effectively.