Wideband spectrum sensing framework for multiple slow frequency hopping primary users

Abstract

Cognitive radios have been advanced as a solution to improve spectral efficiency through opportunistic access of the spectrum by unlicensed users. In order to achieve its objective, a cognitive radio is required to conduct periodic spectrum sensing to avoid interfering with the licensed user of the spectrum. In this paper, we examine a multi-channel occupied by a licensed user (primary user) employing slow frequency hopping to access the channel. This method of access presents a challenge to a sensing cognitive radio node since the primary user effectively spreads its signal over the entire wideband and the spectrum holes are rapidly changing. By adopting a sensing strategy of jointly detecting all subbands in the channel simultaneously, we study the achievable unlicensed user (secondary user) throughput vis-a-vis the allowable interference on the primary network. The investigation is conducted under two cases; when the hop duration of the primary user is either synchronized or unsynchronized to the secondary user's time frame to investigate the effect of time frame misalignment which presents a more realistic model.