An Improved Selection Cooperation Scheme for Decode-and-Forward Relaying

In this letter, an improved selection cooperation (ISC) scheme for decode-and-forward relaying is proposed based on selection cooperation (SC) strategy. Assuming that channels suffer from independent non-identical Rayleigh fading, we derive closed-form expression for the exact symbol error rate (SER) of ISC scheme. The result holds for arbitrary number of relays and refers to both M-PSK and M-QAM modulations. Simulations are carried out to validate the theoretical analysis. Results show that the proposed ISC scheme outperforms SC for all the cases we investigate.