An efficient power allocation algorithm with fairness constraints in cognitive OFDMA system

An efficient power allocation algorithm for OFDMA-based cognitive radio (CR) systems with the total power limitation, interference constraint, and proportional fairness requirement is proposed. While solving the optimization problem with multiple constraints is computationally infeasible, we exploit the structure of the nonlinear equations to obtain an approximate solution. It can fairly allocate power among the second users (SUs) with significantly reduced complexity. Furthermore, we replace the traditional water-filling (WF) algorithm with a much faster alternative that can avoid repeated iterations to facilitate subcarrier power allocation within a single SU. Simulation results show the proposed algorithm can maintain a higher capacity, while effectively ensure the fairness among SUs compared with the referenced algorithms.