Date Added: Jul 2009
Cognitive Radio (CR) can improve spectrum utilization by allowing the secondary users to temporarily access the primary users' unutilized licensed spectrum. In order to guarantee Quality of Service (QoS) of the secondary users, spectrum handoff mechanism must be implemented in CR networks. Spectrum handoff procedures aim to help the secondary users vacate the spectrum and search the target channels to resume the unfinished transmission when the primary user appears at the occupied licensed band. In such a system, the most basic issue is how much CR technique can improve spectrum utilization.