Dynamic Connectivity of Cognitive Radio Ad-Hoc Networks with Time-Varying Spectral Activity

We investigate the dynamic connectivity of cognitive radio ad-hoc networks (secondary networks) coexisting with licensed networks (primary networks) that experience time-varying on-off links. It is shown that there exists a critical density λ_s^* such that if the density of secondary networks is larger than λ_s^* , the secondary network percolates at all time t > 0, i.e., there exists always an infinite connected component in the secondary network under the time- varying spectrum availability. Furthermore, the upper and lower bounds of λ_s^* are derived and it is shown that they do not depend on the random locations of primary and secondary users, but only on the network parameters, such as active/inactive probability of primary users, transmission range, and the user density.