Cooperative relays for an underlay cognitive radio network

A cooperative relaying scheme is proposed for an underlay cognitive radio network where relays use their beam steering capability to impose target SINRs at the secondary user terminals whilst keeping the interference and noise leakage to the primary users below a threshold. The scheme is developed to incorporate per relay antenna power constraint that limits the power emitted by the relays. The scheme is shown to have a better performance, in terms of outage probability and transmission power as compared to a non cooperative relay scheme.