Outage analysis in cooperative cognitive networks with opportunistic relay selection under imperfect channel information

This paper proposes exact and limit outage probability expressions for thoroughly evaluating the performance of cooperative cognitive networks with opportunistic relay selection under imperfect channel information, independent and non-identical (i.n.i.) Rayleigh fading channels, maximum transmit power constraint, and interference power constraint. The proposed derivations can be straightforwardly extended to corresponding analysis in dual-hop cognitive networks with opportunistic relay selection to investigate how much performance gain can be achieved from using the direct channel between the source and the destination in relaying communications. Numerous results illustrate significant outage performance degradation and performance saturation due to channel information imperfection but the degradation and saturation level can be remedied by increasing the number of relays. Also, the channel direct brings a considerable performance improvement without any additional expense of system resources such as power and bandwidth. Moreover, channel information imperfection can cause interference power at primary users to exceed a pre-defined level, deteriorating the quality of service of primary users.