Modeling and Analysis of Sub-Banding the Secondary Users’ Channel in Cognitive Radio Networks

Modern cognitive radio systems employ dynamic spectrum access techniques and these networks allow more efficient usage of scarce spectrum. Secondary users are supposed to operate in primary users’ channels without interfering them. In this paper, we propose model and analyze a channel sub-banding scheme for an opportunistic spectrum sharing system in which two secondary users are allowed to coexist in a channel. In the proposed sharing scheme when all the channels are occupied by the primary and/or secondary users, the channels of the secondary users are divided into two sub bands allowing both of the secondary users exploit the same channel concurrently. The proposed model is analyzed through a two-dimensional Markov chain model and evaluated by different derived metrics including blocking probability and dropping rate. Although using the proposed scheme reduces the quality of service for secondary users because of sub-banding, simulation results show significant reduction in the blocking probability and dropping rate of the secondary users.