Reactive spectrum handoff combined with random target channel selection in cognitive radio networks with prioritized secondary users

Abstract

Cognitive radio aims at improving spectrum utilization by allowing secondary users to access primary user’s spectrum. The delay time of secondary users due to multiple interruptions from primary users is considered a crucial issue. In this work, to reduce secondary user delay time, we propose a mixed preemptive/non-preemptive resume priority model where secondary user priority increases with each interruption by the primary user. We consider reactive spectrum handoff combined with random target channel selection for the case of all-busy channels. We derive closed form expressions of the average cumulative delay time and the extended data delivery time for each secondary user class. Numerical results show that the proposed approach reduces the secondary user delay time per class compared to other models in case of light loaded networks. Keywords: Cognitive radio, Spectrum handoff, Queueing theory, Priority schemes