Interference Evaluation in Ad-Hoc Cognitive Radio Networks

In this paper, we evaluate the total ergodic capacity of channels in an ad-hoc cognitive radio network under interference constraint at the primary users. It is assumed that all links associated with primary and secondary networks experience Rayleigh fading. First, interference from only primary transmitters is discussed. In such case, the optimum power allocation scheme and the ergodic capacity are derived under average interference power constraint. This paper is also extended to include the impact of interference from both primary transmitters and other secondary transmitters. Then, we propose the iterative algorithm to maximize the total capacity due to non-convexity of the objective function. The effect of different types of interference is investigated via numerical analysis.