On the robustness of multiuser diversity in diversity combine systems with channel estimation error

The robustness differences of multiuser maximum ratio combining (MRC), MIMO-MRC and optimum combining (OC) systems with imperfect channel state information are analyzed. Using the multiuser average capacity difference CDR with channel estimation error, the robustness of the three systems are illustrated in a flat Rayleigh fading channel with multiple interferers. Performance results show that OC system always outperforms the MIMO-MRC and MRC systems when there are no co-channel interferences, whereas MIMO-MRC and MRC outperform the OC system when there are multiple co-channel interferences.