Contract Theory Based Medium Access Contention Resolution in TDMA Cognitive Radio Networks

Abstract

Time-division-multiple-access-based cognitive radio networks allow each licensed primary user to transmit its packets exclusively. The available idle slots present an opportunity to the unlicensed secondary users (SUs) to access the licensed channel for their own transmission. The different SUs contending to access the channel during idle time slot may result in collisions and unfair allocation of the channel. To overcome such a situation, this paper proposes a contract theory based bargaining approach to resolve access contention among SUs in a centralized manner. Contract theory is an incentive design mechanism where participants are offered appropriately designed reward to encourage cooperation. To achieve this, the interaction between the secondary base station (BS) and SU is modeled as a labor market using contract theory. First, the ideal case of SUs is examined where the private information of the SUs is completely known to the BS. Next, the practical case of incomplete information is considered where the BS has no private information of the SUs. The preferences of an SU to access the channel is categorized into a finite number of type using the framework of contract-theory. Further, the overall service time of an SU is also analyzed. The simulation results show that the contract can effectively incentivize SU's cooperation, and outperforms the considered benchmark scheme in terms of SU's overall throughput and average service time.