New two-hop multiple relay protocol with H-ARQ in the absence of a direct link

In this paper, we devise and comprehensively analyze an efficient transmission protocol for multiple half-duplex relay communication without a direct link but with inter-relay interference. The proposed protocol achieves high diversity gain with the help of Hybrid Automatic Retransmission reQuest (H-ARQ) even when multiplexing gain is quite high. As the maximum allowable number of retransmission rounds (L) increases, an additional time diversity gain is obtained in short-term static channels. Compared to pre-existing protocols which adopt H-ARQ in a similar manner, its diversity gain at high multiplexing gain is much improved. As L increases, the dominating region become wider. In addition, in long-term static channels, we show that more than two retransmissions (i.e., L > 2) are unnecessary for improvement of the diversity gain.