Cooperative Hybrid-ARQ Protocols: Unified Frameworks for Protocol Analysis
Cooperative Hybrid-Automatic Repeat reQuest (HARQ) protocols, which can exploit the spatial and temporal diversities, have been widely studied. The efficiency of cooperative HARQ protocols is higher than that of cooperative protocols because retransmissions are only performed when necessary. The authors classify cooperative HARQ protocols as three Decode-and-Forward-based HARQ (DF-HARQ) protocols and two Amplified-and-Forward-based HARQ (AF-HARQ) protocols. To compare these protocols and obtain the optimum parameters, two unified frameworks are developed for protocol analysis. Using the frameworks, they can evaluate and compare the maximum throughput and outage probabilities according to the SNR, the relay location, and the delay constraint.