Analysis of cognitive cooperative networks with best relay selection and diversity reception

This paper analyzes outage performance of cognitive cooperative networks with best relay selection (BRS) and maximum ratio combining (MRC) under maximum transmit power constraint, licensed outage constraint, erroneous channel information, independent non-identical (i.n.i) fading channels, and licensed users´ interference. To this end, we firstly propose power allocation for unlicensed transmitters to meet power constraints and account for erroneous channel information and licensed users´ interference. Then, we propose an exact closed-form outage probability formula for the unlicensed network to quickly provide useful insights into system performance. Various results demonstrate error floor in the unlicensed network, performance trade-off between the unlicensed network and the licensed network, substantial system performance degradation owing to erroneous channel information and licensed users´ interference, and considerable performance enhancement due to the increase in the number of relays.