Performance Analysis of Cognitive Radio Spectrum Access with Prioritized Traffic

Dynamic spectrum access (DSA) is an important design aspect for the cognitive radio networks. Most of the existing DSA schemes are to govern the unlicensed user (i.e., secondary user) traffic in a licensed spectrum without compromising the transmissions of the licensed users, in which all the unlicensed users are typically treated equally. In this paper, prioritized unlicensed user traffic is considered. Specifically, we prioritize the unlicensed user traffic into two priority classes (i.e., high and low priority). Two different DSA policies are proposed to manage the prioritized unlicensed user traffic. These two policies are different in which one does not allow the high priority secondary user to be dropped, while the other allows if the system is full and has some low priority secondary users. We also study the impact of sub-channel reservation for the high priority secondary users in both DSA policies. Both DSA policies are analyzed using Markov chain. For performance measures, we derive the blocking probability, the probability of forced termination and the throughput for both high, and low priority unlicensed users. The numerical results are verified using simulations.