Channel-Hopping Based on Available Channel Set for Rendezvous of Cognitive Radios

Abstract—Rendezvous is a necessary operation for cognitive users to establish communication links in cognitive radio net-works (CRNs). To guarantee the rendezvous in finite time, all existing rendezvous algorithms generate CH (channel-hopping) sequences using the whole channel set and attempt rendezvous on each of the channels (i.e., both available channels and unavailable channels). In practice, the available channel set is usually a small portion of the whole channel set due to dynamics of channel availabilities and limited sensing capabilities of cognitive users. Thus, the CH sequences using the whole channel set may attempt unnecessary rendezvous in uncertain channels (e.g., unavailable channels or randomly-selected channels) which greatly degrades the performance. In this study, we propose a new rendezvous algorithm that generates channel-hopping sequences based on available channel set (CSAC) for more efficient rendezvous. We prove that CSAC gives guaranteed rendezvous and derive its upper-bound on maximum time-to-rendezvous (MTTR) which is an expression of the number of available channels instead of the number of all potential channels. To the best of our knowledge, CSAC is the first one in the literature that exploits the only available channels in designing CH sequences while providing guaranteed rendezvous. Experimental results show that CSAC can significantly improve the MTTR compared to state-of-the-art. Index Terms—cognitive radio; rendezvous; channel hopping. I