Quality of hybrid services in cognitive radio networks

QoS guarantee for cognitive radio network is a great challenge, especially for hybrid services. In fact, secondary users´ requirements for QoS are not identical due to the hybrid services typically including real-time and non real-time. So, in this paper, we consider in our system model two types of services, real-time and non real-time. We divide the secondary users into two priorities and propose a spectrum handoff mechanism and a resource reservation policy, implementing different strategies for different services to strictly guarantee the QoS of secondary users with hybrid services while maximizing the throughput of cognitive radio networks. The cognitive radio system is depicted with the aid of a multi-dimensions Continuous-Time Markov Chain (CTMC) model, where we derive the main performance metrics for secondary users including the session blocking probability, dropping probability, throughput and mean handoff delay. Numerical results confirm the validity of the proposed model and schemes for hybrid services in cognitive radio networks.