LAUSR

Cognitive radio network can improve under-utilized licensed wireless channels called the primary channels where secondary users (SUs) can opportunistically share the primarychannels allocated to primary users (PUs) but which are not used by the PUs. This paper proposes a priority-based reservation medium access control protocol in cognitive radio network where a common control channel is exclusively used for SUs to transmit control packets in order to determine the priority for accessing the primary channels. The position of a control packet that did not collide with others becomes a priority. With the proposed protocol, any new SUs can join the network whenever it wants without knowing any past information. The analytic results show that the number of SUs affects the performance due the collision possibility of random access. However, if the SU can transmit its control packet successfully without collision, then it can transmit its data packet based on its priority without worrying about additional collision.