Blocking Rate Analysis in Heterogeneous Multicell Cognitive-Radio 5G Networks

Cognitive radio (CR) technology is being recognized as one of the main enabling technologies for supporting massive high-speed connectivity in multicell fifth-generation (5G) networks by allowing dynamic spectrum access policies according to predetermined etiquette. Under this paradigm, the available spectrum is opportunistically allocated to the different cells. A key metric that is heavily employed in designing efficient CR-based multicell spectrum-allocation mechanisms is the blocking rate. An efficient spectrum-allocation mechanism aims to adaptively allocate channels to the different cells such that the overall blocking rate is minimized. In this article, we use the theory of continuous-time Markov chains to derive a closed-form expression for the blocking rate in multicell CR-based 5G networks. In our derivations, we build two detailed mathematical models describing the frequency-spectrum usage of both primary and secondary users. We combine the two models in a hierarchical fashion. As opposed to related models in the literature which suffer high complexity, the proposed hierarchical structure yields simplicity and tractability. Furthermore, while existing research works overlook spectrum heterogeneity, the proposed model addresses this important factor. Simulation results demonstrate high accuracy in evaluating the blocking rate across the different cells in the network.