A bandwidth-efficient cooperative relaying scheme with limited feedback information

We propose a cooperative relaying scheme using a K-antenna relay to assist information transmission of M single-antenna users to a common N-antenna destination, K, N ≥ M. All M users simultaneously transmit their information in one time-slot to exploit distributed MIMO multiplexing gain and hence high bandwidth efficiency. The relay will inform the detection status of M user signals received in time-slot 1 so that, in time-slot 2, the relay only re-transmits T successfully detected users’ signals over its T randomly selected antennas (where T≤M) while the (M-T) other users will re-send their signals. Outage probability of the proposed scheme is derived. Numerical results show that the proposed scheme provides significant performance improvement.