Cooperation based Spectrum Management Scheme in Ad-hoc Cognitive Radio System

In cognitive radio (CR) ad-hoc systems, the performance of system can be increased by using cooperation between cognitive users. In this paper, we compare three cooperation schemes for CR ad-hoc systems which are non-cooperation, sensing-cooperation and full-cooperation of sensing and band, in which the spectrum information or the band can be cooperatively shared among cognitive users. Unlike other cooperative sensing schemes which focus on cooperative sensing on single band, our cooperation model focuses on cooperative sensing on multiple bands. We propose the concept of spectrum pool which is the common knowledge on spectrum among cognitive users and this spectrum pool is maintained by sharing sensing results of sensing users on different bands. Given that the cognitive users have more information on the spectrum compared to the case when there is no information sharing, the number of sensing attempts to find vacant band can be reduced and the performance of CR system can be improved. We analyze the performance of three cooperation schemes by using game theory and state transition diagram. Through simulation, we show that our analysis is well matched to simulation results. We also find that the throughput can be improved by utilizing spectrum pool and the throughput can be deteriorated due to the selfish behavior of cognitive users when band can be shared by the cognitive users.