Improved Soft Pilot Reuse Combined with Time-Shifted Pilots in Massive MIMO Systems

摘要

Each user inside the cell of massive multiple- input multiple-output (MIMO) system suffers from severe pilot contamination (PC), which directly decreases the quality of service. To mitigate the PC, this paper proposes an improved soft pilot reuse scheme combined with time-shifted pilot arrangement, named by TS-SPR. First, we divide the users inside the cell into two parts: the center users and the edge users. For the center users, we divide all cells into three groups and implement the time- shifted pilot transmissions in uplink training stage. For the edge users, a filtering approach based on fast Fourier transform (FFT) operation is proposed to extract desired signals from interfering signals by the non-overlapping angle- of-arrivals (AOAs). Simulation results show that the proposed TS-SPR scheme can effectively improve the overall performance of the system without extra cost of pilot resources.