Spectrum Availability Recheck Scheme (SARS) for cognitive radio systems with mobility

We consider the change of spectrum availability which is caused by the mobility of a cognitive radio (CR) user. Given that the CR user should not interfere with a primary user (PU), it should periodically check the availability of the CR band which is being used. Herein, we refer the scheme to check the availability of spectrum as SARS (Spectrum Availability Recheck Scheme). We propose a SARS for both CR systems which use a geo-location database to find vacant band and CR systems which use spectrum sensing to find vacant band. The proposed SARS adaptively changes its operation according to the velocity of a CR user. Through the analysis and the simulation results, we have shown that the spectrum availability of a CR user can be efficiently verified by using proposed SARS, when the CR user moves. We also have shown that the overheads caused by our SARS is low.