On the outage performance of relaying cognitive networks with reactive relay selection and selection combining

This paper analytically evaluates the outage performance of relaying cognitive networks with reactive relay selection and selection combining under general operation conditions such as independent non-identical (i.n.i) fading channels, mutual interference between primary network and secondary network, peak transmit power constraint, primary outage constraint, and channel information imperfection. To this effect, we first propose power allocation for secondary users to satisfy both constraints and account for mutual interference and channel information imperfection. Then, we suggest an exact closed-form outage probability expression for secondary destination to quickly assess system performance in key operation parameters and provide useful insights into performance limits. A multitude of results demonstrate significant system performance degradation due to channel information imperfection and mutual interference, error floor in secondary network, a performance trade-off between primary network and secondary network, and considerable performance enhancement in accordance with the increase in the number of involved relays¹.