In multi-cell massive multiple input multiple output (MIMO) systems,pilot contamination (PC) has become the bottleneck that restricts the performance of the whole system.From a system level point of view,this paper proposes a pilot allocation scheme based on the alternately fractional pilot reuse (AFPR).In the scheme,the users at the age of neighbor cells are allocated orthogonal pilot sequences meanwhile the users at the center of the cells are multiplexed pilot sequences of neighbor cell edge users.At the same time,the expression of the spectral efficiency (SE) is derived theoretically based on AFPR.The numerical simulation results show that the proposed scheme can significantly improve the system performance gain compared to the conventional pilot allocation schemes for the maximum ratio combining (MRC) receiver or the zero forcing (ZF) receiver.%在多小区大规模多输入多输出(Multiple Input Multiple Output,MIMO)系统中,导频污染(Pilot Contamination,PC)已成为制约整个系统性能的瓶颈.本文从系统级角度出发,提出了一种基于部分导频交替复用(Alternately Fractional Pilot Reuse,AFPR)的导频配置方案,即相邻小区的边缘用户配置相互正交的导频序列,而小区中心用户复用相邻小区边缘用户所配置的导频序列.同时从理论上推导出基于AFPR的导频配置方案上行可达频谱效率(Spectral Efficiency,SE)的关系式.数值仿真结果表明,相比于传统的导频配置方案,无论采用最大比合并(Maximum Ratio Combining,MRC)还是迫零(Zero Forcing,ZF)接收,该方案可显著地提升系统性能增益.
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