End-to-End Error-Rate Based Incremental Relaying for AF Cooperative Communications

Incremental relaying (IR) was previously proposed to mitigate the spectral-efficiency loss in cooperative communications. In this letter, based on the amplify-and-forward (AF) protocol with M-ary phase-shift keying (M-PSK) signals, we propose a new way to implement IR with better spectral efficiency. Specifically, based on the end-to-end symbol error rate (e2e SER), an uncertainty region for detection is defined. Only if the processed signal at the destination falls into this region, the included relays will perform AF relaying. Simulations reveal that in terms of the e2e SER performance, the proposed IR-AF scheme performs quite well as compared with the conventional signal-to-noise ratio (SNR)-based IR-AF method, and, importantly, with significantly lower average relay usage.