Security game between source and friendly relay

In this paper, we investigate a four terminal Gaussian network which is composed of a destination, a source, an eavesdropper and a friendly relay which helps the source to increase the secrecy capacity. We introduce a game theoretic approach in which the source pays the relay for increasing the secrecy capacity. The relay charges the source with a certain price, and there is a tradeoff for the price. If the price is too high, the source would not buy the "service", but if the price is too low the profit of the relay is low. In modeling the outcome of the above games we use Stackelberg type of game. In our work we prove the existence of the Stackelberg equilibrium of the game. Simulation results and analysis show the effectiveness of the relay and the tradeoff of the price.