Connectivity of hybrid overlay/underlay cognitive radio ad hoc networks

In this paper, we study the connectivity of a hybrid cognitive radio ad hoc network (H-CRAHN) in which each secondary user can be able to use either overlay cognitive radio or underlay cognitive radio paradigms to access a licensed spectrum. Specifically, we carry out a simulation-based analysis to investigate the connectedness between two arbitrary nodes in the H-CRAHN. Considering such a hybrid network, we propose an algorithm to calculate the path probability which measures the connectivity of the network. We then exam what network parameters that impact on the connectivity of the H-CRAHN. The simulation results show that by using the hybrid underlay/overlay transmission mode at the SUs, the path probability increases compared to the use of only underlay mode or overlay mode. In addition, active rate of primary user, node density, and transmit power play key roles in the study of the network connectivity.