Spectrum Capacity for Ad Hoc Networks Using Cognitive Radios: An Analytical Model

Dynamic spectrum access (DSA) is an important design aspect for the cognitive radio networks (CRNs). Most of the existing DSA schemes are to govern the secondary user traffic in a licensed spectrum without considering the transmissions also in the unlicensed bands. In this paper, we propose two DSA schemes (i.e., without and with buffer) for cognitive radios access in both licensed and unlicensed bands in a distributed CRN. A Markov chain analysis for each of the proposed DSA schemes is presented and forced termination probability, blocking probability and traffic throughput are derived. In addition, we discuss a number of errors in the Markov model and analysis of the blocking and forced termination probabilities in a CRN, given in Al-Mahdi et al. (IEEE Commun Lett 13(9):676–678, 2009). This paper shows the corresponding correct derivations and results, and simulation results are given to support our analyses.