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 …