A New ARQ Protocol for Hybrid DF/CF Relay Scheme

Automatic Repeat re-Quest (AQR) is implemented to ensure reliable transmission when Channel State Information (CSI) is not available to the source and the selected transmission rate is not supported by the current channel realization. The authors consider a relay system with hybrid relay scheme, where the relay switches between Decode-and-Forward (DF) and Compress-and-Forward (CF) adapting to the decoding status. In such case, they propose new ARQ strategy and analyze its performance in terms of maximum throughput, average reward and inter-renewal time. Compared with pure DF, the hybrid relay schemes show considerable gain.