- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
An important issue in designing multichannel MAC protocols for Opportunistic Spectrum Access (OSA) is the synchronization between Secondary Users (SUs). Synchronization can be performed in two phases: the initial handshaking, and then the synchronous hopping across available channels. In this paper, we address the problem of initial handshaking through the approach called “blind rendezvous”. We first introduce a role-based solution by constructing two channel hopping sequences. The secondary transmitter and receiver jump across channels according to these two sequences. The proposed algorithm guarantees rendezvous in at most (C+1)2 time slots (where C is the number of channels) and two SUs have a chance to rendezvous in each successive period of C time slots. We show that this property of constructed sequences leads to a lower average time-to-rendezvous (TTR) for the proposed algorithm in comparison to other related works. We also devise a solution to ensure rendezvous in the presence of jitter. Next, we extend the proposed algorithm to the non-role-based scenario. Simulation results show that it has the best performance with respect to existing works in various traffic patterns of primary users. Besides, it is the most predictable solution due to its low variance of TTR.
In this paper, we proposed the PJR algorithm for rendezvous in CR networks. We first considered a role-based solution and showed that it ensures rendezvous in at most (C + 1)2 time slots. Furthermore, the PJR algorithm has better performance than the other existing work, the ACH algorithm, in terms of ETTR due to the specific property of constructed sequences. We also studied the case in which there is a mismatch between the duration of time slots in two SUs and give a solution to guarantee rendezvous in this condition. Afterwards, we proposed the mPJR algorithm for non-rolebased case. Simulation results showed that the proposed algorithm has the lowest ETTR in various PUs’ traffic patterns with respect to other related works. Besides, its variance of TTR is the lowest among other algorithms under almost all cases which makes it a promising solution for rendezvous in CR networks.