Date Added: May 2012
This paper investigates a multiuser MIMO relay downlink system with imperfect channel estimation and limited feedback. Compared with the system using perfect Channel State Information (CSI), they analyze the achievable rate loss due to CSI mismatch arising from both channel estimation and CSI quantization feedback. An upper bound to the rate loss is firstly derived to characterize the effect of imperfect CSI. Given the rate loss bound, the authors then present a limited feedback strategy for both two-hop channels in the relay system to guarantee a bounded rate loss for growing SNRs.