Multiple Access Games with a Cognitive Eavesdropper
Karim Khalil, Eylem Ekici · arXiv (Cornell University) · 2012
We consider two-user multiple access games in which one player (primary user) is interested in maximizing its confidential data rate at the minimum possible transmission power and the other player (secondary, cognitive user) employs eavesdropping as a leverage to maximize its data rate to a common destination at minimum transmission energy. For the non-cooperative static game, Nash equilibria in pure and mixed strategies are derived and shown to be Pareto inefficient for certain ranges of channel gains and energy cost parameters, when channel gains are common knowledge. A Stackelberg game formulation is then considered where the primary user is the leader. Interestingly, it is shown that the secondary user is forced to play as the follower where the Stackelberg equilibrium dominates the Nash equilibrium, even if the eavesdropper channel is better than the primary channel. Here, the Stackelberg utility achieved Pareto dominates the achieved Nash utility. Finally we study the unknown eavesdropper channel case numerically where the primary user has only statistical knowledge about the channel gain. We compare the results to the first scenario and show that it is not always beneficial for the cognitive user to hide the actual eavesdropper channel gain.