Physical layer security game: How to date a girl with her boyfriend on the same table

Physical layer security is an emerging security concept that achieves perfect secrecy data transmission between the intended network nodes, while the eavesdropping malicious nodes obtain zero information. The so-called secrecy capacity can be improved using friendly jammers that introduce extra interference to the eavesdropping malicious nodes while the interference to the intended destination is limited. In this paper, we investigate the interaction between the source that transmits the desired data and friendly jammers who assist the source by "disguising" the eavesdropper. In order to obtain a distributed solution, we introduce a game theoretic approach. The game is defined in such a way that the source pays the friendly jammers to interfere the eavesdropper, and, therefore, increasing its secrecy capacity. Friendly jammers charge the source with a certain price for this "jamming service". There is a tradeoff for the price: If the price is too low, the profit of the jammers is low; and if the price is too high, the source would not buy the "service" (jamming power) or would buy it from other jammers. To analyze the game outcome, we define and investigate a Stackelberg game and construct a distributed algorithm. Our analysis and simulation results show the effectiveness of friendly jamming and the tradeoff for setting the price. The fancy title comes from the fact that it is similar to a scenario where the main fellow character (the source) tries to send a dating message to a lady (the intended destination), whose "poor" boyfriend plays the role of the eavesdropper that may hear the message. Friends of the source, the so-called "friendly jammers," try to distract the boyfriend, so that the dating message can be secretly transmitted. The game is defined in order to derive what is the optimal price that the friends can charge for this "friendly" action.