Channel Hopping Sequences for Maximizing Rendezvous Diversity in Cognitive Radio Networks

TL;DR

This paper investigates the fundamental limits of channel hopping sequences in cognitive radio networks, deriving bounds and proposing an asymmetric design that minimizes rendezvous time metrics, especially for odd numbers of channels.

Contribution

It derives lower bounds on rendezvous time metrics and proposes a new asymmetric sequence design that optimally minimizes these metrics, improving over existing methods.

Findings

Proposed design achieves minimum MCTTR.

Improves MTTR compared to previous algorithms.

Achieves minimum MTTR when the number of channels is odd.

Abstract

In cognitive radio networks (CRNs), establishing a communication link between a pair of secondary users (SUs) requires them to rendezvous on a common channel which is not occupied by primary users (PUs). Under time-varying PU traffic, asynchronous sequence-based channel hopping (CH) with the maximal rendezvous diversity is a representative technique to guarantee an upper bounded time-torendezvous (TTR) for delay-sensitive services in CRNs, without requiring global clock synchronization. Maximum TTR (MTTR) and maximum conditional TTR (MCTTR) are two commonly considered metrics for evaluating such CH sequences, and minimizing these two metrics is the primary goal in the sequence design of various paper reported in the literature. In this paper, to investigate the fundamental limits of these two metrics, we first derive lower bounds on the MCTTR and MTTR, and then propose an asymmetric design which has the minimum MCTTR and an improvement on MTTR than other previously known algorithms. Moreover, when the number of licensed channels is odd, our proposed design achieves the minimum MTTR. We also present the TTR performance of the proposed design via simulation.