Energy-efficient cooperative diversity with incremental relaying

Based on switched relays, an energy-efficient cooperative diversity scheme is addressed and its performance is analyzed. With switched relays, relying is only used when the signal-to-noise ratio (SNR) of the source-to-destination (SD) channel is lower than a preset threshold, and in addition, an activated relay will further process the received source signal only if the transmission over its source-to-relay (SR) channel also has a satisfied signal-to-noise ratio (SNR), which will save relay-processing resource including the relay energy for transmitting the SR data over relay-to-destination (RD) channels. Both decode-and-forward (DF) and amplify-and-forward (A F) relaying policies are considered. The outage probability and the bit error probability (BER) of BPSK signaling on independent and identically distributed (i.i.d.) Rayleigh fading channels are derived. Numerical results are presented for performance illustrations.