Markovian Queuing Model for Dynamic Spectrum Allocation in Centralized Architecture for Cognitive Radios

Abstract

Dynamic Spectrum Allocation (DSA) is one of the latest technologies serving to cater to rising demand of spectra. Since a decade, cognitive radios (CR) are looked upon as a solution to increase spectral efficiency. However, to make CR a reality, development of air interface is a big challenge. In this paper, we have proposed a CR architecture followed by its equivalent mathematical model. We consider a centralized network where the master/controller of this ad-hoc network coordinates for spectrum allocation with the surrounding CR in the network. This CR ad-hoc network is assumed to coexist with the network of licensed users where the controller of licensed users is updated with CR coordinating engine. The mathematical model is formed of two Markovian distributed queues. One of these queues is modeled as M/M/1 and the second as M/G/S/N. Mathematical analysis of our proposal is focused to evaluate bandwidth access latency of an unlicensed user.