Date Added: Aug 2009
In this paper, the authors model and analyze the interactions between secondary users in a spectrum overlay cognitive system as a cognitive MAC game. In this game, each secondary user can sense (and transmit) one of several channels, the availability of each channel is determined by the activity of the corresponding primary user. They show that this game belongs to the class of congestion game and thus there exists at least one Nash Equilibrium. They focus on analyzing the worst case efficiency loss (i.e., price of anarchy) at any Nash Equilibrium of such a game. Closed-form expressions of price of anarchy are derived for both symmetric and asymmetric games, with arbitrary channel and user heterogeneity.