Abstract
In a communication system, security and reliability have an important impact on the quality of services. In this paper, we investigate power and subcarrier allocation of a transmitter over the downlink of an OFDMA system with security considerations among users in the presence of a jammer. This paper considers the interaction between the jammer and the transmitter as a zero-sum game where the objective function is the transmitter's secrecy sum-rate. In order to allocate available resources, we solve the optimization problem of each player to characterize their optimal strategies. Considering the intractability of the closed form Nash equilibrium for general power regime, we show the existence of pure Nash equilibrium point for low total power regimes of the transmitter and the jammer and attain an expression for each regime. Finally, we examine the jamming power effect on the secrecy sum-rate and acquire lower and upper bounds of this rate using simulations.