Performance analysis of SNR-based incremental hybrid decode-amplify-forward cooperative relaying protocol

In this paper, we propose and analyze a new relaying scheme for the three-node cooperative relaying system, named as incremental hybrid decode-amplify-forward relaying (IHDAF), where the relay may choose to keep silent or transmit message in decode-and-forward (DF) or amplify-and-forward (AF) mode based on the qualities of the channels among the source, relay, and destination. Closed-form expressions of the outage probability and bit error rate (BER) of the proposed IHDAF protocol are derived. The optimal relationship of the two important signal-to-noise ratio (SNR) thresholds at the relay and destination to decide whether cooperation is necessary and the cooperative mode has been achieved. Moreover, the effects of the power allocation schemes, SNR thresholds, and relay locations on the outage probability and BER of the IHDAF protocol are studied. Theoretical analysis and simulation results show that the IHDAF relaying scheme outperforms the incremental-selective DF (ISDF), incremental DF (IDF), and cooperative STBC schemes, especially when the relay is close to the destination.