Bargaining to Improve Channel Sharing between Selfish Cognitive Radios

We consider a problem where two selfish cognitive radio users try to share two channels on which they each have potentially different valuations. We first formulate the problem as a non-cooperative simultaneous game, and identify its equilibria. For cases where the resulting Nash equilibria are not efficient, we then propose a novel coordinated channel access mechanism that can be implemented with low overhead in a decentralized fashion. This mechanism, based on the Nash bargaining solution, guarantees full utilization of the spectrum resources while improving the utility of each user compared to the non-cooperative setting. We quantify the resulting gains. Finally, we prove that risk-averse users that are willing to accept offered information at face value have no incentive to lie to each other about their valuations for the non-cooperative game. However, we find that truthfulness is not guaranteed in the bargaining process, suggesting as an open problem the design of an incentive compatible mechanism for bargaining.