A State-based Transmission Coordination Strategy for Channel-Hopping Cognitive Radio Networks

Recently, with the concept of blind rendezvous, numerous channel-hopping sequence (CHS) based rendezvous schemes have been proposed to solve the rendezvous problem for neighbor discovery in distributed cognitive radio networks (CRNs). However, the related rendezvous problem for data exchange is not paid the due attention. In this paper, on the basis of existing CHS based rendezvous schemes, we investigate the rendezvous de-synchronization problem in the transmission coordination strategy used by CH-based multiple rendezvous MAC for data transmission. This problem degrades network performance (e.g, packet delivery delay and network throughput) by destroying connectivity between secondary users (SUs), especially in heavily loaded CRNs. To this end, we propose a state-based transmission coordination (STC) strategy which assigns active or inactive state to each SU across hop slots. As SUs with inactive state can be successfully located by their active neighbors, the rendezvous de-synchronization problem is restrained. Moreover, the STC strategy has an extra capability of alleviating multi-user contention to further improve network performance. Extensive simulations demonstrate that the STC strategy can improve network performance more effectively than its counterpart.