Outage Priority Based Relay Fairness in Opportunistic Cooperation

The opportunistic cooperation schemes, where only the “best” relay is selected to forward the message, are well performed in outage probability but with poor fairness among relays. In this paper, we introduce the concept “outage priority based fairness” (OPF), aiming at improving the fairness appropriately without outage performance deterioration. A novel cooperation scheme is proposed to meet the concept and theoretical analysis is provided further. Then, based on OPF, the achievable upper bound of the fairness is derived and an optimal cross-layer designed scheme is also provided to achieve the bound. Numerical simulations are carried out finally, which validate the correctness of our analysis and show that in the proposed schemes, the fairness among all relays is greatly improved especially in high SNR regime, without any loss of outage performance.