Optimal Power Allocation and Ergodic Capacity in Cognitive Radio Network

Sammanfattning: Cognitive radio network allows the secondary users (SUs) in a secondary communication network (SCN) coexist with priority users in a priority communication network (PCN). The interference caused by SCN to PCN is required to be rational and not affected the quality of server within the PCN to each priority users (PUs). In this paper, we study the optimal power allocation method to achieve the maximum ergodic capacity of both PU fading channel and SU fading channel under different power constraints. The interference power constraints at PU and the transmit power constraints at SU are considered, and the power constraints is distinguished as the peak power constraint and average power constraint. Different combinations of power constraints are analyzed under the particular system and channel fading model. This paper shows that in different scenarios the optimal power of SCN do exist to reach the maximum ergodic capacity of the entire system including SCN and PCN.