Power allocation for regenerative cognitive relay networks with QoS-guaranteed primary user

In this paper, we investigate the problem of optimal power allocation for a two-hop cognitive radio relay network over independent Rayleigh fading channels. We take into consideration of the transmit power limit at the secondary transmitter and relay where the powers are limited to guarantee the quality of service of the primary user. To minimize the secondary outage probability, we re-formulate the power allocation problem with a new set of constraints and achieved the closed form optimal solution. Simulation results confirm the performance improvement of the proposed power allocation scheme.