Abstract:

an adaptive feedback algorithm for multi-user multi-input multi-output （MIMO） system based on hybrid automatic repeat request (HARQ) is proposed in this paper. In the proposed scheme, base station receives the acknowledgement/no acknowledgement (ACK/NACK) from all users in HARQ processes, analyses the channel state and pairing state of scheduled users, controls the feedback of channel state information （CSI） from users, schedules and precodes the users to enhance the system capacity. The proposed scheme has the advantage of low feedback as well as low complexity and outperforms the traditional multi-user MIMO system. Especially, when high SNR regime or in high-speed mobility, this scheme alleviates the ceiling effect of multi-user MIMO.

Key words: multi-user multiple input multiple output, limited feedback, hybrid automatic repeat request