A two-stage-game-based power control scheme for OFDMA-relay channels under physical layer security requirement

In this paper, we develop a distributed power control scheme for relay channels with confidential message in an uplink OFDMA-relay cellular by Amplify-and-Forward mode. We introduce a two-stage game in a progressive optimization. In this scenario, the relay is considered not only as a sender that assists the information transmission, but also as an eavesdropper who can wiretap information. In the two steps, we design two different form of utility function for ensuring the reliability in the relay channel and enhancing the security capacity of each user. In addition, the existence of Nash Equilibrium in the two steps of the game model is confirmed. Simulation results demonstrate that the proposed scheme can effectively ensure the security capacity requirement for each user as well as achieve the fairness of power allocation in users, in addition of energy conservation.