Outage Probability Analysis of Multi-Relay Delay-Limited Hybrid-ARQ Channels

The authors consider a wireless relay network with Hybrid-Automatic Retransmission reQuest (HARQ) and Rayleigh fading channels. In this paper, they analyze the outage probability of the multi-relay delay-limited HARQ system with opportunistic relaying scheme in decode-and-forward mode. A simple and distributed relay selection strategy is proposed for multi-relay HARQ channels. Then, they analyze the performance of the system. They first derive the Cumulative Density Function (CDF) and Probability Density Function (PDF) of the selected relay channels. Furthermore, closed-form upper-bounds on outage probability are derived, which are used to investigate the diversity order of the system.