Spectrum sharing by sub-banding in cognitive radio networks

Dynamic spectrum access techniques utilized in cognitive radio systems allow more efficient use of spectrum. In such systems, secondary users are supposed to operate in primary users´ spectrum without interfering them. In this paper, we investigate an opportunistic spectrum sharing technique in cognitive radio networks for a special case in which, two secondary users are allowed to coexist in a channel (sub-banding). The sub-banding process in the proposed algorithm is such that, when all the channels are occupied by the primary and secondary users, then the secondary users´ channels can be divided into two subbands, and two secondary users may use a sub-band, simultaneously. For performance evaluation, we have derived metrics such as blocking probability, dropping probability, and channel utilization, and then, the simulation results for the cases of using and not using sub-banding for the secondary users have been compared. It is observed that in a spectrum sharing system, channel sub-banding significantly reduces the blocking and dropping probabilities of the secondary users, with the cost of lower quality channels compared to the state without using sub-bands.