A two-layer coalitional game among rational cognitive radio users

In cognitive radio (CR) networks, secondary users (SUs) sense the spectrum to identify and possibly transmit over temporarily unoccupied channels that are licensed to primary users (PUs). However, when the received PU signal is weak, spectrum sensing by individual SUs becomes unreliable. To improve sensing accuracy, SUs can form disjoint coalitions and cooperate to discover idle time slots. These spectrum opportunities are then shared among the coalition members in a coordinated manner. It is proposed to decouple the coalition formation and the access (payoff) allocation problems by modeling these processes as a two-layer coalitional game. This game fosters cooperation by providing each SU with the access opportunities it deserves. Numerical results demonstrate that the proposed game outperforms previously investigated collaborative sensing and access approaches in terms of energy efficiency, throughput, and fairness.