Adaptation between codebook based SU-MIMO and MU-MIMO with single MCS feedback in LTE

This paper utilizes an adaptive modulation and coding (AMC) scheme and compares the performance of adaptation between single-user multiple input multiple output (SU-MIMO) and multi-user (MU) MIMO with that of SU-MIMO. In long term evolution (LTE), every UE only needs to feed back SU-MIMO rank 1 channel quality indicator (CQI) which could get feedback overhead and computational complexity reduction. This CQI message contains a specific MCS index predicted by the UE. In this AMC scheme, MU-MIMO modulation and coding scheme (MCS) of a user equipment (UE) can be obtained from its SU-MIMO rank 1 (single stream transmission) MCS. According to the SU-MIMO rank 1 MCS and MU-MIMO MCS obtained, we can achieve adaptation between SU-MIMO and MU-MIMO by two-user orthogonal pairing and proportional fair (PF) scheduling. Simulation results show that the adaptation can achieve significant improvement on spectrum efficiency (SE) compared with SU-MIMO by means of the AMC scheme proposed in this paper.