A new MAC scheme in cognitive network for different priority of secondary users

The cognitive networks need the flexible utilization of the spectrum and bandwidths, without impacting the licensed Users(also called Primary Users, PU). While the cognitive radio network Media Access Control (MAC) layer is required not only to provide traditional services but also to perform an entirely new function for effective using the available bandwidths for the unlicensed users called Secondary Users (SU). To solve the problem, this paper develops a new MAC scheme that allows unlicensed users adaptively select spectrum, and it supports the QoS of high priority unlicensed users. The proposed MAC protocol offers differentiated access through the SUs´ parameters setting AIFS[AC], CWmin[AC], CWmax[AC]. Each AC is equipped with a transmitting queue. Simulations verify the proposed MAC scheme for cognitive networks.