Queueing based spectrum management in cognitive radio networks with retrial and heterogeneous service classes

Abstract

Cognitive radio is an emerging technology, aimed at efficient use of the scarce radio spectrum. In cognitive radio networks (CRNs), spectrum licensed to the primary users (PUs) is shared by the secondary users (SUs) which affects the performance of the network. This paper proposes a novel spectrum management scheme for CRNs, where heterogeneous secondary real-time and non-real time users compete for the available channels with primary users and utilize two types of buffers under the probability retrial policy. To enhance the quality of service (QoS) for the secondary users (SUs), spectrum handoff and call buffering strategies with retrial policy are employed jointly so that SUs that would otherwise be blocked or forcibly dropped could be queued and possibly served later. The whole system is modeled using a multi-dimensional continuous-time Markov chain (CTMC) and accordingly, the QoS performance metrics are derived. Numerical results are presented which illustrate that the provision of queues under the proposed retrial policy increases overall network resource utilization and throughput while decreasing blocking and dropping probabilities.