Outage-optimal relaying through opportunistic hybrid forward cooperation

In this paper, a new scheme based on relay selection and data forwarding in multi-relay cooperative networks is introduced. Unlike most existing solutions focused on amplify-and-forward (AF) or decode-andforward (DF) protocol separately, the proposed hybrid forward (HF) scheme takes advantage of both AF and DF protocols in relay forwarding. Based on theoretical analysis, a closed-form expression for the tight lower bound of its outage probability is derived, and further performance analysis is also presented. Then, in total power restricted networks, an optimal power allocation strategy between the source and the selected relay is developed to minimize the outage probability. Simulations are carried out finally, which validate the analysis and show that the HF scheme outperforms other existing ones in terms of outage probability.