A Dynamic Pilot Allocation Scheme in Massive MIMO Systems

Abstract

Massive Multi-Input Multi-Output (MIMO) is one of the key technologies for the fifth generation (5G) cellular networks. As the number of antennas increases, pilot contamination (PC) is considered as one of the main limiting factors for the performance of massive MIMO systems. In this paper, a new dynamic pilot allocation scheme is proposed to mitigate the pilot contamination with low complexity. In this scheme, a pilot reuse indicator is introduced and each cell is divided into center zone and edge zone. When the pilots are allocated, the pilots for edge zone users are dynamically selected according to the pilot reuse indicator. So the scheme can mitigate the pilot contamination by reducing pilot repetition in the target cell and neighbor cells, improve the system capacity. Our simulation results show that the proposed scheme can significantly increase the uplink achievable rate and provide better stability in the scenario with nonuniform distributed users, especially with more users and less pilots.