Hybrid-Optimization-Based Power Allocation for Cognitive Relay Transmission

In this paper, we study the power allocation for both regenerative and non-regenerative relay transmission over Rayleigh fading channels in cognitive networks. Based on the analyses of features of cognitive networks, a relevant interference model is first built over Rayleigh fading channels. Then, we propose a combined power allocation strategy in order to minimize the outage probabilities in the cooperative communications. For regenerative system, we give a closed-form expression for the power allocation by taking into account the characteristics of the fading channels. For non-regenerative system, we utilize pattern search algorithm to solve the optimization problem since the objective function is complex and uneasy to be figured out directly. Numerical results show that the system performances with optimum power allocation outperform those with uniform power allocation whereas lower outage probabilities can be obtained.