Pilot Contamination Reduction Method with Alternately Fractional Pilot Reuse for Multi-cell Massive MIMO Systems

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 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.