Optimal Power Allocation for Multichannel Cognitive Radio Systems Using Stackelberg Game

We consider a non-orthogonal multiple access scheme e.g. CDMA based cellular multi-channel cognitive radio network (CRN). Here multiple secondary users share a common set of channels simultaneously. For such an environment, we develop a distributed power allocation approach based on a game theoretic formulation among secondary users to satisfy their rate requirement. We model the problem using a two-stage leaderfollower game known as Stackelberg game where base station and users are considered as leader and followers respectively. Since the spectrum is licensed to a primary network, base stations of the cellular secondary network should protect primary users against interference caused by secondary communications. We are interested for downlink power allocation with pricing that maximizes utilities of both BS and CRs in presence of primary network. A nonlinear relationship which is developed between bit rate and SINR is solved by game theory. Simulation results show that our proposed power control scheme provides higher SINR levels (or equivalently higher data rates) while consuming lower average transmit power of secondary users. Keywords–Cognitive radio network(CRN), power allocation, non-cooperative game, Stackelberg game, Nash equilibrium(NE), pricing, QAM, ASK, PSK and BER.