Mutual Information Jammer-Relay Games
Tairan Wang, Georgios B. Giannakis · IEEE Transactions on Information Forensics and Security · 2008
We consider a two-person zero-sum mutual information game between one jammer (J) and one relay (Rfr) in both nonfading and fading scenarios. Assuming that the source (S) and the destination (D) are unaware of the game, we derive optimal pure or mixed strategies forJand Rfr depending on the link qualities and whether the players are active during theSrarrDchannel training. In nonfading scenarios, when bothJand Rfr have full knowledge of the source signal, linear jamming (LJ) and linear relaying (LR) are shown optimal in the sense of achieving Nash equilibrium. When theSrarrJandSrarrRfr links are noisy, LJ strategies (pure or mixed) are still optimal under LR. In this case, instead of always transmitting with full power as when theSrarrRfr link is perfect, Rfr should adjust the transmit power according to its power constraint and the reliability of the source signal it receives. Furthermore, in fading scenarios, it is optimal forJto jam only with Gaussian noise if it cannot determine the phase difference between its signal and the source signal. When LR is considered with fading, Rfr should forward with full power when theSrarrRfr link is better than the jammedSrarrDlink, and defer forwarding otherwise. Optimal parameters are derived based on exact Nash equilibrium solutions or upper and lower bounds when a closed-form solution cannot be found.