A General Power Allocation Algorithm for OFDM-Based Cognitive Radio Systems

In OFDM-based cognitive radio systems, the interference power limits of the primary users (PUs) introduce subchannel transmit power constraints for the secondary user (SU). The power allocation among the subcarriers of SU should be subject to both the sum transmit power constraint as well as the transmit power constraint of each subchannel. Different from previous works, we deal with a more general case where the subcarrier sidelobes are specially considered. A general power allocation algorithm is proposed to obtain the optimal solution that maximizes the capacity while satisfying both the sum and subchannel transmit power constraints.