On Using Spectrum History to Manage Opportunistic Access in Cognitive Radio Networks

Cognitive radio networks (CRNs) open up the underutilized parts of the licensed spectrum for secondary reuse, so long as this secondary access does not cause harmful interference to the licensed users. Being able to run CRNs in a completely decentralized manner, as opposed to centralized operation, can be quite advantageous, because it avoids the complexity and single point-of-failure issues that arise from the presence of a central controller, and also eliminates the difficult step of establishing and maintaining a common control channel, which can suffer from saturation and malicious attacks. To that end, we propose in this paper a novel decentralized spectrum allocation technique for CRNs that not only provides great performance in terms of high throughput, excellent fairness, and minimal interference between cognitive users but also provides very stable network operation, in which cognitive users do not have to switch their operating frequency quite regularly. This is achieved by systematically observing the history of the spectrum usage to determine the proper channel assignment in the CRN. Our proposed technique is intuitive, is completely decentralized, and allows for quick reaction to changes in the CRN, such as when the primary users licensed to use the spectrum are suddenly activated.