Limited Feedback Open Loop Precoding in the Downlink Relay Multiuser MIMO System

In the wireless communication system, multi-input multi-output technique can be used to increase capacity. In the MIMO system, the non-linear precoding can archive the MIMO channel capacity through perfect feedback with a high complexity. To reduce the complexity, linear precoding with limited feedback information rate is used in most of simultaneous communication system. Further more, open loop precoding is also able to reduce the complexity. Since the codebook has been chosen in the transmitter side, the size of codebook could be enlarged to reduce the loss from deviation of the quantification of codebook. Compare between the full feedback of open loop linear precoding in Relay Multi User MIMO system and the limited feedback of open loop precoding, we can conclude that this open loop precoding in relay MU-MIMO has a low feedback information rate with small capacity loss.