Decode-and-forward buffer-aided relay selection in cognitive relay networks

This paper investigates decode-and-forward (DF) buffer-aided relay selection for underlay cognitive relay networks (CRNs) in the presence of both primary transmitter and receiver. We propose a novel buffer-aided relay selection scheme for the CRN, where the best relay is selected with the highest signal-to-interference ratio (SIR) among all available source-to-relay and relay-to-destination links while keeping the interference to the primary destination within a certain level. A new closed-form expression for the outage probability of the proposed relay selection scheme is obtained. Both simulation and theoretical results are shown to confirm performance advantage over the conventional max-min relay selection scheme, making the proposed scheme attractive for CRNs.