A pilot allocation scheme for TDD massive MIMO system enabled HetNet

摘要

A pilot allocation (PA) scheme is propose to reduce pilot contamination for time division duplex (TDD) massive multiple-input multiple-output (MIMO) system enabled two-tier heterogeneous cellular network (HetNet). In order to reduce inter-tier interference during channel estimation, proposed scheme assigns mutually orthogonal pilots between macro-cells and small-cells, and pilots are reused among macro-cells with different pilot reuse factors. Comprehensive analyses and simulations of uplink average signal to interference plus noise ratio (SINR) and average achievable ergodic rate for the proposed scheme are developed. Simulation results show that the proposed PA scheme can reduce pilot contamination and improve the SINR and ergodic rate at base stations (BSs). In addition, the average SINR increases when pilot reuse factor grows, which shows the benefit of the proposed scheme. The average ergodic rate first becomes larger and then becomes smaller when pilot reuse factor becomes larger, which means the large number of pilot symbols limits the increase of ergodic rate.