Adaptive power allocation for three transmission phases cognitive relay networks with data rate fairness

In this paper, we consider a two way cognitive relay network using decode and forward (DF) protocol over Rayleigh fading channels. Under the joint outage constraint of the primary user (PU) caused by a pair of secondary transmitters (ST) and the secondary relay (SR), the problem of power allocation for the secondary users (SU) is reformulated. We derive the optimal power allocation algorithm for the SUs based on the data rate fairness, under the proposed primary user outage probability constraint. Simulations and comparisons are presented to illustrate the effectiveness of our proposed power allocation scheme.