A Dual Modular Clock Algorithm for Cognitive Radio-based Emergency Response Network

Natural and human induced calamities can cause loss of lives and service disruption which requires immediate response setup for first responders and victims. In the aftermath of a disaster first 48 hours are crucial to provide temporary response network for responders to coordinate and conduct search and rescue operation in case of fully or partially destroyed telecommunication infrastructure until more stable help arrives. However, the problem remains the little or no information about the environment in which initial setup needs to operate. A cognitive radio in this regard has a potential to establish initial link in an unknown environment to provide rapid deployment with efficient spectrum usage. A rendezvous protocol can be used to establish initial link, but unpredictable and unknown environment can increase the rendezvous time due to the existence of Primary Radio (PR) activity. The existing protocols have limitations of index based channel selection, inefficient use of spectrum, time slot duration, hopping rate and rendezvous cycle. This paper proposes a dual modular clock-based rendezvous algorithm (DMCA), which takes advantage of prime and non-prime channel numbers to enhance spectrum utilization and incurs less rendezvous time. In the worst-case scenario of asymmetric, which involves only two similar channels (m = 2) with high PR activity, our DMCA protocol achieves 69%, 44%, and 21% less rendezvous time compare to traditional protocols proposed for unknown environments.