An MAC protocol enabling fast rendezvous for secondary users in cognitive networks based on two-stage sensing

Here we proposed a periodical two-stage sensing MAC protocol for the cognitive network which enables the sender sense the same channel with its intended receiver through sensing only two channels at most, thus the sender and receiver don´t need to sense a large number of channels to find a channel that is idle to both of them for data transmission. Each secondary user (SU) randomly chooses a channel to sense in the 1st sensing phase and report its sensing result, then each SU can know the channel its intended receiver had sensed in the 1st sensing phase, then it decides whether to sense the channel in the 2nd sensing phase. On some conditions satisfied, it conducts the 2nd stage sensing and negotiates with its receiver to reserve the channel. We design two negotiation schemes, the negotiation is conducted on the control channel in the 1st scheme and on the data channels in the 2nd scheme. Finally, we used NS-2 to analysis the performance of the protocol using the two negotiation schemes.