An Improved Relay Selection Scheme with Hybrid Relaying Protocols

In this paper, we propose an improved relay selection scheme based on a hybrid relaying protocol (RS-HRP). In the proposed scheme, all the relays are included into two groups, referred to as an amplify and forward (AAF) and a decode and forward (DAF) relay groups. The relays which decode successfully are included in the DAF group and the rest of relays, which fail to decode correctly, are included in the AAF group. The best relay, which maximizes the destination SNR, will be selected from all relays in both AAF and DAF relay groups. If it is selected from the AAF group, it will amplify the received signal while if it is selected from the DAF group, it will decode the received signals and re-encode. Results show that the proposed relay selection scheme significantly outperforms the conventional AAF selection scheme and this performance gain considerably grows as the number of relays increases. It also approaches the perfect DAF relay selection as the SNR increases.