Link Maintenance Protocol for Cognitive Radio System with OFDM PHY

For secondary usage of spectrum in a cognitive radio system, in order to maintain reliable continuous communication among secondary users, secondary radios need to make contact, communicate and switch to an open RF channel simultaneously when the current channel is reclaimed by a primary user. In this paper, we describe a link maintenance protocol aimed at solving this issue. The communication channel is monitored and dynamically updated based on spectrum availability. Spectral sensing is employed at the receivers to monitor the spectrum and assist in RF channel synchronization between transmitter and receiver. Simulation results characterizing the performance of this protocol are provided. A prototype system with a pair of cognitive radios featuring this protocol is also introduced.