Channel Availability Analysis for Sensing Order Selection in CRNs with Correlated Channels

In cognitive radio networks (CRNs), channel availability is one of the key factors in constructing policies for sensing order selection. It provides information about the channel occupancy and enables second user to find the available channel efficiently. In this paper we investigate the channel availability in a CRN system with correlated channels, by introducing the concept of the conditional consecutive idle probability (CCIP) of the channel. In the scenario where the primary user's occupancy follows M/M/c/c queue we derive the CCIP of the channel according to the historical occupancy observations of the spectrum. As an example of the application in sensing order selection, the number of consecutive idle slots (NCIS), which impacts the reward of SU, is then obtained based on the CCIP of the channel. Numerical results verify the theoretical results produced in this paper.