Non-Cooperative Feedback Control Game for Improving Throughput Fairness in MIMO Broadcast Channels

Channel state information (CSI) is known to play crucial role for downlink transmissions of multi-user multiple-input multiple-output (MU-MIMO) systems. The existing works have been widely researched on the CSI feedback problem for system throughput aspects. With limited available radio resources, system throughput and fairness are usually in conflict with each other, balancing system throughput and fairness with high resource efficiency is necessary. Also, the analysis of feedback-rate allocation considering these two performance measures is needed. Therefore, in this paper, we propose the non-cooperative feedback-rate control game for improving throughput fairness in MU-MIMO system. Based on the game theory, the utility function of each user is considered both throughput fairness and total throughput. Moreover, we investigate the existence of the Nash-equilibrium of the proposed game and outage probability in terms of CSI feedback-rate. Simulation results show that the proposed game improves throughput fairness, and thus achieves better outage performance, as compared to the conventional equal-sized feedback scheme.