Abstract
Aiming at an efficient use of the channels available in the wireless spectrum, cognitive radio networks (CRNs) allow users to adapt to the environment by reusing the existing spectrum. A secondary (unlicensed) user (SU) is allowed to operate in the licensed band of the primary user (PU) after sensing the spectrum and making sure that it would not interfere with it. Normally, a SU transmits over spectrum holes, and when a PU wants to switch on to her channel, the SU gets hanged and her transmission stops. Such a network alters the seamless communication and raises challenges regarding the transmission of delay-sensitive traffic like multimedia. In this paper, a new algorithm that adds a proactive behavior for channel allocation at the medium access control (MAC) layer is proposed: Before hopping into a licensed channel (LC), the SU reserves her unlicensed channel (UC) for a token time (TT), such that if a PU reclaims her LC within this time, the SU can hop back into her previous channel seamlessly. The value of TT was varied, and the effect of this variation showed favorable results on delay and jitter.