Route-switching games in cognitive radio networks

In Cognitive Radio Networks (CRNs), Secondary Users (SUs) are provided with the flexibility of accessing Primary Users' (PUs') idle spectrum bands but the availability of spectra is dynamic due to PUs' uncertain activities of channel reclamation. In the multi-hop CRNs consisting of SUs as relays, such spectrum mobility will cause the invalidity of pre-determined routes of data flows since some of the channels pre-assigned to the routes become unavailable. In this paper, we investigate the spectrum-mobility-incurred route-switching problem in both spatial and frequency domains for CRNs, where the spatial switching determines which relays and links should be re-selected and the frequency switching decides which channels ought to be re-assigned to the spatial routes. We further formulate the route-switching problem as the Route-Switching Game which is shown to be a potential game and has a pure Nash Equilibrium (NE). Accordingly, an efficient algorithm for finding the NE is proposed. The proposed route-switching scheme not only avoids conflicts with PUs but also mitigates spectrum congestion. Meanwhile, tradeoffs between routing costs and channel switching costs are achieved.