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The Stochastic Properties of Cognitive Networks under RD Mobility Model

The cognitive networks can increase the spectrum utilization efficiency by allowing the Secondary User (SU) to occupy the licensed frequency of primary user (PU). The movement of PU may leads to an intermittent end to end path for SU during the communications, which may affect the routing performance. So it is important to analyze SU's stochastic properties to optimize the routing design. The previous work in term of PU mobility mainly focuses on its impact on the spectrum sensing. While in this paper, we aim to study the PU mobility in term of routing design, and study the stochastic properties including the hitting time, meeting time, contact time and inter-contact time under the random direction mobility model by combining with the new features of the cognitive networks technologies. We derive the closed-form expressions for these properties and observe that the mobility will increase the spectrum occupancy time to improve the throughput of SU because mobile nodes are hard to encounter others, and we get that the routing design of cognitive networks should carefully choose the transmission range of SU to reduce the contact time and enlarge the hitting time and meeting time to improve the routing stability.