A Neighbor Cooperation Framework for Time-efficient Asynchronous Channel Hopping Rendezvous in Cognitive Radio Networks

The establishment of common control channel (CCC) is an immense challenge in cognitive radio networks (CRNs). Since the channel number is large and the channel access is opportunistic, the process (a.k.a. rendezvous) that any pair-wise nodes (i.e. rendezvous pair) find a common channel to establish a control channel for communication is hard to achieve, especially in a distributed CRN. Researchers have proposed sequence-based asynchronous channel hopping (ACH) protocols to guarantee rendezvous between transmitting and receiving nodes without requirement of global synchronization. However, these existing protocols emphasize on how to construct the sequences of channel hopping (CH). Even worse, the rendezvous pair in these protocols loyally follow their respective predefined channel hopping sequences before meeting each other (i.e. rendezvous success), which causes rendezvous performance dominated by the sequence structure to be hardly improved further and results in intolerable rendezvous delay due to large channel number and opportunistic access in CRNs. We propose a neighbor cooperation framework by observing sequence diversity in existing ACH protocols, which enables the rendezvous pair to adapt their CH sequences before rendezvous success and improve rendezvous performance with the cooperation of neighboring nodes. Extensive simulation results show that the rendezvous performance of existing ACH protocols can obviously be improved in this framework by cooperation of small number of cooperative neighbors.