Fully Distributed Channel-Hopping Algorithms for Rendezvous Setup in Cognitive Multiradio Networks

Abstract

Abstract-Channel rendezvous is a vital step to form a cognitive radio network (CRN). It is intractable to guarantee rendezvous for secondary users (SUs) within a short finite time in asynchronous, heterogeneous, and anonymous CRNs. However, most previous heterogeneous algorithms rely on explicit SUs' identifiers (IDs) to guide rendezvous, which is not fully distributed. In this paper, we exploit the mathematical construction of sunflower sets to develop a single-radio sunflower set (SSS)-based pairwise rendezvous algorithm. We propose an approximation algorithm to construct disjoint sunflower sets. Then, the SSS leverages the variant permutations of elements in sunflower sets to adjust the order of accessing channels instead of SUs' IDs, which is more favorable for anonymous SUs in distributed environments. We also propose a multiradio-sunflower-set-based pairwise rendezvous algorithm to bring additional rendezvous diversity and accelerate the rendezvous process. Moreover, for the case with more than two SUs, we propose a multiuser collaborative scheme in which SUs cooperatively exchange and update their channel-hopping sequences until rendezvous. We derive the theoretical upper and lower bounds of rendezvous latency of the proposed algorithms. Extensive simulation comparisons with the state-of-the-art blind-rendezvous algorithms are conducted, incorporating the metrics of maximum and expected time-to-rendezvous. The simulation results show that our algorithms can achieve rendezvous faster than previous works.

Efficient Matrix-Based Channel Hopping Schemes for Blind Rendezvous in Distributed Cognitive Radio Networks

“…However, establishing rendezvous under the asymmetric model is more difficult due to the fewer common channels.Heterogeneous sensing capabilities: Most of the existing CH schemes are homogeneous where they assume that all SUs can sense and access the whole global channel set (GCS). However, due to the inherent limitation and heterogeneity of CR-sensing capabilities, SUs can only sense and detect fractions of the GCS which are usually heterogeneous among SUs [21,22]. Accordingly, CH schemes which design their CH sequence for heterogeneous CRs are more practical.…”

“…On the other hand, each of the above categories can be classified according to the channel information utilized to generate the CH sequence into two classes: Global-Channel-based (GC) and Local-Channel-based (LC) schemes [21,22]. The GC schemes utilize the whole GCS to generate their CH sequences where SUs keep hopping on the available and unavailable channels for attempting rendezvous.…”

“…This replacement strategy is not effective and still results in relatively high MTTR [24]. Meanwhile, the LC schemes generate their CH sequences based on the ACSs which make them more practical in distributed CRNs due to the spatial and temporal variations in channel availability as well as the limitation and heterogeneity of SUs sensing capabilities [21,22,24]. However, the majority of existing LC schemes failed to solve the issue efficiently, where they either rely on unfavorable assumptions and unpractical restrictions to guide rendezvous or still produce long TTR due to the inefficient mathematical tools utilized in their designs.…”

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.…”

A Novel Multi-radio Rendezvous Algorithm for Cognitive Radio Networks

“…Current algorithms suitable for multi-rendezvous utilize concepts of traditional, user-to-user rendezvous and either add or adapt features to scale the solution [7,15,2]. Most rendezvous algorithms rely on a channel hopping scheme where users "hop" onto different frequencies in a specified sequence or pattern in order to achieve rendezvous [13,4,12]. Some classic blind rendezvous algorithms that use channel hopping sequences are the Generated Orthogonal Sequence, Modular Clock, and Modified Modular Clock algorithms, etc.…”