A Fast Multi-Radio Rendezvous Algorithm in Heterogeneous Cognitive Radio Networks

Abstract

In this paper, we propose a fast rendezvous algorithm for a heterogeneous cognitive radio network (CRN), where each user might have more than one radio. One of the wellknown problems for most multi-radio rendezvous algorithms in the literature is that they are not backward compatible to users with only one radio. To tackle this backward compatibility problem, our approach is a hierarchical construction that groups several time slots into an interval and proposes a novel algorithm to emulate two radios with a single radio in an interval. By doing so, at the interval level, each user behaves as if it had (at least) two radios. For the two-user rendezvous problem in a CRN with commonly labelled channels, the interval length is chosen to be 2M time slots, where = 2 ⌈log ₂ (⌈log ₂ N⌉)⌉ + 10. We show that the maximum time-to-rendezvous (MTTR) of our algorithm is bounded above by 18M⌈n ₁ /m ₁ ⌉ . ⌈n ₂ /m ₂ ⌉ time slots, where 1 (resp. 2) is the number of available channels to user 1 (resp. 2), and 1 (resp. 2) is the number of radios for user 1 (resp. 2). For the setting that each user is equipped with only one radio and two available channels, our MTTR bound is only and that improves the state-of-the-art bound 16(⌈log ₂ log ₂ N⌉ + 1) in the literature. By conducting extensive simulations, we show that the expected time-to-rendezvous (ETTR) of our algorithm is also better than the two commonly used multi-radio algorithms, JS/Independent and JS/Parallel, in most parameter settings.