A transparent spectrum co-access protocol for cognitive radio networks

In this paper, we address the challenge of providing secondary users access to licensed spectrum when there are active primary user transmissions. The motivation is to eliminate the disruption to secondary user communications by the resurgence of primary user transmissions. We propose a novel protocol, termed spectrum co-access protocol (SCAP), for secondary users to transparently and simultaneously access spectrum with primary users. This protocol enables mutually beneficial coexistence between the primary user network and the secondary user network. Through spectrum co-access, SCAP creates a virtual SU control channel in licensed spectrum that is transparent to the PU. The result is a unique medium access control protocol that allows for transparent simultaneous spectrum access between the SU and PU networks. The performance evaluation indicates that SCAP provides significant performance improvement for the SU network over the existing opportunistic spectrum access scheme.