On the DMT of bidirectional relaying with limited feedback

Several half-duplex decode-and-forward two-way relaying protocols that efficiently exploit quantized channel state information (CSI) at the transmitters (CSIT) are investigated. Adapting the number of channel uses for each relaying phase and the transmit power based on limited CSIT is shown to result in a significant improvement in the diversity-multiplexing tradeoff (DMT). With CSI feedback from relay to sources, allocating the number of channel uses is sufficient to match the performance of power allocation. However, power control is instrumental to efficiently exploit CSI feedback from sources to relay.