Channel state information (CSI) reporting at one mobile station (MS) often targets maximizing the throughput of one single link, hence is optimized for single-user multi-input multi-output (SU-MIMO) transmission at base station (BS). However, the system wide throughput may not be maximized when BS is performing multi-user multi-input multi-output (MU-MIMO) transmission utilizing the SU-MIMO optimized CSI reports, and vice versa. This CSI mismatch can cause system throughput degradation. In this paper, a novel CSI feedback method is proposed which can switch between SU-MIMO optimized CSI reporting mode and MU-MIMO optimized CSI reporting mode when instructed by BS’s signaling. System level simulation results show when BS is performing MU-MIMO transmission, significant throughput gain can be obtained if MS feeds back MU-MIMO optimized CSI reports instead of SU-MIMO optimized CSI reports. With the instruction of the BS signaling to dynamic indicate MS to switch between SU-MIMO and MU-MIMO optimized CSI reporting modes, the SU-MIMO performance is not compromised either.
Wireless communication SU-MIMO MU-MIMO CSI reporting Feedback