Reliability Analysis of Combing Space-Time Block Codes and Opportunistic Scheduling in MIMO Rayleigh Channels with Channel Estimation Error

In order to utilize the multiuser diversity (MUD) efficiently in multiuser MIMO systems, a MIMO system that combing space-time block codes and opportunistic scheduling (OS) was presented, where the user with the largest throughput was adaptively selected according to channel state information (CSI) feedback from the receive side, and the impact of channel estimation error on the reliability was investigated. Firstly, we derive both exact closed-forms and approximate expressions of the outage probability and BER for M-ary QAM and PSK modulations. Then, the diversity order was quantified through asymptotic analysis and ratio of diversity gain was compared between perfect and imperfect CSI cases. Finally, the corresponding simulation results indicated that the reliability of this scheme was improved by MUD and the loss of diversity gain was caused by channel estimation error.