MU-MIMO user pairing algorithm to achieve overhead-throughput tradeoff in LTE-A systems

This paper investigates user pairing algorithm in multiple-user multi-input multi-output (MU-MIMO) systems. Considering that users report Precoding Matrix Index (PMI) and Rank Indicator (RI) to indicate precoding matrix, multiple orthogonal PMI&RI clusters are designed to reduce the MU-channel state indicator (MU-CSI) feedback overhead. On the basis of such predefined orthogonal clusters, a novel user pairing algorithm is proposed to make the tradeoff between cell throughput and MU-CSI feedback overhead. To further simplify computational complexity, we propose a suboptimal algorithm. Unlike previous researches, the transmission data streams of paired users are adaptively adjusted according to the channel condition. Simulation results show that the cell throughput gain achieved by our proposed algorithms is close to that achieved by other user pairing algorithms, with less feedback overhead in Long Term Evolution-Advanced (LTE-A) systems.