Single Relay Selection in the Cognitive Cooperative Network: Toward Bandwidth Efficiency Improvement

This paper investigate and enhances the bandwidth efficiency in the underlay cognitive cooperative network with a reactive relay selection under interference and power constraints. In other words, this paper inspects how unlicensed cooperative users utilize the licensed network slot(s) or sub-channel(s) efficiently. To this end, a relay selection method named as Relay Automatic Repeat Request (RARQ) is proposed and utilized with a cognitive cooperative network under interference and power constraints. The bandwidth efficiency of cognitive cooperative network is higher than that of cooperative transmission due to the interference and power constraint. Furthermore, the bandwidth efficiency of cognitive cooperative network is affected by the distance of the interference links which are between the unlicensed transmitter to the licensed destination and unlicensed relay to the licensed destination.