DH-MAC: A Dynamic Channel Hopping MAC Protocol for Cognitive Radio Networks

Abstract

In this paper, we propose a channel-hopping MAC protocol called dynamic hopping MAC (DH-MAC) to improve the utilization of spectrum in cognitive radio networks. In DH-MAC, each secondary user (SU) switches its operation channel with a channel-hopping sequence which is adaptive to the activity of primary users (PUs). Our proposed DH-MAC mechanism enjoys the following merits. 1) It needs no dedicated common control channel for operation. 2) It supports multiple rendezvous for multiple simultaneous transmission pairs of SUs within the interfering range. 3) The rendezvous channel of two SUs will not be blocked by PUs for a long time. 4) It allows SUs a higher probability to operate on available channels as compared with existing schemes. 5) One cognitive radio transceiver is sufficient. The simulation results show that DH-MAC outperforms existing schemes in terms of higher aggregate throughput and more robustness to the disturbance of PUs.

CACH: Cycle-Adjustable Channel hopping for control channel establishment in cognitive radio networks

“…The number of channels N is set to 13. When there are 10,20,30,40, and 50 SUs distributed randomly in a 1000mx1000m region, the average number of neighbors of an SU is 5, 11, 16, 22 and 28 respectively. When the number of neighbors is larger than 10, the number of logical channels of CACH is set to the number of channels.…”

“…In fact, RRICH is a generalization of SSCH in two folds: (i) RRICH uses the field operations which are much more general than the prime number modular arithmetic in SSCH, and (ii) RRICH implements "rotation" under the operation and thus the degree of overlapping is N, i.e., all the channels. Note that the idea of using "rotation" was previous used in our early conference paper [10]. As a special case of Corollary 4, the worst case TTR for RRICH is N+1 time intervals when there is no PU blocking, i.e., .…”

“…A CH scheme is called asymmetric if one SU can be identified as the sender and the other SU can be identified as the receiver. For asymmetric CH schemes (such as ACH in [18] and ARCH in [19]), the sender and the receiver can use different strategies to rendezvous and thus can achieve better performance than symmetric CH schemes (such as SSCH in [7], SYN-MAC in [8], QCH in [9] and DH-MAC in [10]), where both SUs have to follow the same strategy. Also, a CH scheme is synchronous if the indices of time intervals of both SU are the same.…”

“…In general, one can increase system load to reduce TTR and such a tradeoff can then be used to optimize system performance. Unfortunately, most existing CH schemes [7][8] [10]- [16] in the literature were designed for a fixed environment and they cannot be easily adjusted to optimize system performance.…”

The Life Cycle of the Rendezvous Problem of Cognitive Radio Ad Hoc Networks: A Survey

“…In channel hopping approaches, SUs generate their own channel hopping sequences [14]. When an SU (e.g., a sender) needs to communicate with its neighbor (the receiver), it switches from one channel to another, by following a predefined hopping-sequence, until it finds its neighbor [15,16].…”