Joint Power Control and Pilot Assignment Algorithm in Multi-cell Multi-user Massive MIMO Systems

Abstract

In multi-cell multi-user massive MIMO systems, pilot contamination(PC) caused by pilot reuse will reduce the performance of channel estimation. Aiming at the drawbacks of the weighted graph coloring based pilot decontamination (WGC-PD) algorithm, the pilot assignment ignores the users of lower potential pilot contamination, which allocates the pilot of lower interference for the user of higher potential pilot contamination sequentially, and a joint power control and pilot assignment algorithm is proposed. The proposed algorithm improves the WGC-PD algorithm, sets a threshold in pilot assignment, determines whether assign small interference pilot to this user, and establishes the optimization model by combining pilot power control after pilot assignment, further reduces pilot contamination and maximizes the uplink achievable sum-rate. The simulation results show that, compared with the WGC-PD algorithm, the proposed algorithm can guarantee the performance of the users with small potential pilot contamination and obtain higher uplink achievable sum-rate