Matrix-Based Channel Hopping Algorithms for Cognitive Radio Networks

Abstract

Cognitive radio networks (CRNs) have emerged as a critical technique to solve spectrum shortage problem and enhance the utilization of licensed channels. To prevent from interfering with the co-locate incumbent networks, before data transmission, nodes in CRNs should rendezvous on an available channel (i.e., idle licensed channel) for establishing a link or exchanging control information. However, implementing rendezvous is challenging because the availability of channels is time-varying and position-varying. For reducing rendezvous failure and increasing throughput, a node pair in CRN should be able to rendezvous on every licensed channels (i.e., maximizing rendezvous diversity) and rendezvous on an available channel as soon as possible (i.e., minimizing maximum conditional time to rendezvous (MCTTR)). Besides, in order to take full advantage of the frequency diversity of multi-channel medium access, rendezvous should be spread out in time and channel (i.e., minimizing channel loading). In this paper, we proposed two rendezvous channel hopping algorithms, T-CH and D-CH, which can be used without time synchronization and role preassignment (each node has a pre-assigned role as either a sender or a receiver). D-CH requires that SUs in CRNs should have unique ID (identifier), while T-CH does not. Both of our T-CH and D-CH have maximum rendezvous diversity and minimum channel loading, and outperform in terms of MCTTR.

On Channel Hopping Sequences With Full Rendezvous Diversity for Cognitive Radio Networks

“…From practical considerations, it may be desirable to require each SU to perform sensing to remove unavailable channels from consideration in its CH sequences [9], [10]. However, in this paper we do not adopt this approach.…”

“…Asymmetric approaches require each SU to have a preassigned role as either a sender or a receiver, and allow the sender and the receiver to use different approaches to generate their respective CH sequences, while symmetric approaches do not. As summarized in [9], [12], previously known asymmetric ones such as A-MOCH [4], ACH [5], ARCH [6], D-QCH [10], and WFM [11] all produce smaller MCTTR than previously known symmetric ones, such as CRSEQ [1], JS [2], EJS [3], Sym-ACH [5], DRDS [7], HH [8], T-CH [9] and S-QCH [10]. However, to the authors' best knowledge, the following two fundamental problems have not been settled until now.…”

Efficient rendezvous schemes for fast‐varying cognitive radio ad hoc networks

“…Many CH-based rendezvous schemes have been proposed in the literature. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] These schemes can be categorized in different ways, according to the adopted assumptions and mathematical construction tools. A detailed survey of the rendezvous issue in cognitive radio ad hoc networks (CRAHNs) and the different categories of the CH-based rendezvous schemes is well studied in the work of Joshi et al 24 However, most of the existing CH rendezvous designs were not tailored for fast PU dynamics, where channel availabilities can vary during the rendezvous operation itself.…”

“…The rendezvous occurs between a pair of communicating SUs when they hop during the same time slot over a channel that is commonly available for both of them. Many CH‐based rendezvous schemes have been proposed in the literature . These schemes can be categorized in different ways, according to the adopted assumptions and mathematical construction tools.…”

Combined Sector and Channel Hopping Schemes for Efficient Rendezvous in Directional Antenna Cognitive Radio Networks

“…Therefore, channel hopping (CH) has been proposed as an alternative approach for rendezvous without the need for any predefined CCC. The existing CH-based rendezvous schemes were designed with omnidirectional antenna according to different mathematical structures (e.g., [9][10][11][12][13][14][15][16][17][18]) in order to provide a successful channel rendezvous between a pair of single-hop SUs. In the CH approach, each SU generates its CH sequence 2 Wireless Communications and Mobile Computing based on the available channels that are sensed to be idle from any PU activities within its omnidirectional range.…”