Channel-Hopping Sequences with Flexible Channel Labeling for Cognitive Radio Wireless Networks

Channel-hopping (CH) protocols are essential in modern cognitive radio (CR) technology, as they facilitate rendezvous between secondary users (SUs) and improve spectrum efficiency by enabling dynamic access to limited spectral resources. Traditional CH protocols rely on a global-labeling framework, assuming that all SUs share the same mapping scheme from logical channels in their CH sequences to physical frequencies in their CR transceivers. However, when SUs operate in different regions or encounter varying frequency availability, this framework can lead to mismatches in channel-to-frequency mappings, hindering effective channel rendezvous. This paper proposes two construction algorithms for asynchronous universal-labeling (UL) CH sequences that adapt flexibly to both global and autonomous labeling scenarios. Simulation and numerical analyses demonstrate that the proposed UL CH sequences achieve an optimal balance of maximum rendezvous diversity, even channel utilization, and minimal maximum time-to-rendezvous, thereby enhancing spectrum flexibility and efficiency in CR wireless networks.