Performance Analysis of Hybrid-ARQ with Chase Combining over Cooperative Relay Network with Asymmetric Fading Channels

This paper investigates the performance of cooperative relay networks in the presence of hybrid automatic repeat request (ARQ) with delay constraint. It analyzes the scenarios where the relay channels are asymmetric (i.e., the links of the wireless relay network follow different fading distributions) due to relaying position and/or due to time varying channel fading. The analytical expressions for the outage probability and throughput are derived for different asymmetric fading channels. The benefit of combined implementation of relaying and hybrid-ARQ is illustrated. Our results show that the performance in terms of outage probability and delay-limited throughput is better when the relay node is in line-of-sight (LoS) with respect to the source node compared to being close to the destination node. This performance difference is quantified and can be as large as several dB depending on the specific configuration. This difference in performance narrows when the maximum hybrid-ARQ transmission rounds increase or when the information transmission rate decreases.