Pilot Contamination Reduction Scheme in massive MIMO systems based on chain network

According to the characteristics of massive MIMO and multi-cell TDD system in the chain network, a new pilot contamination reduction scheme is proposed. At first, every cell is divided into left area and right area, and orthogonal pilot sequences are divided into three groups. Secondly, the three groups of pilot sequences are distributed to left or right area’s users in turn and circularly in the chain network. The target user and the adjacent area’s user are arranged orthogonal pilot sequences, and the target user and the remote area’s user are multiplexed pilot sequences. So the pilot contamination is reduced. The numerical simulation results show that the throughput of the proposed scheme is superior to the pilot power control scheme because the uplink channel estimation time of the new scheme is reduced. The number of the proposed scheme’s calculation is small compared with the pilot exhaustive enumeration scheme. The proposed scheme has a certain practical value.