An analysis of asynchronism of a neighborhood discovery protocol for cognitive radio networks

Abstract

Due to the changing network topology and the time and location varying spectrum availability in Cognitive Radio Networks (CRNs), there is a need of on-demand searching for a control traffic channel by CR users in order to be able to initiate a communication. This neighborhood discovery phase, also referred to as a rendezvous (RDV) phase, is challenging due to the dynamics of CRNs. There are a number of different proposed solutions (pseudo-random or systematic approaches such as quorum systems) to tackle this issue, however, not so many elaborate on the asynchronous character of CRNs, and even less taking into account channel heterogeneity in terms of quality. In this study, on the one hand, we propose a novel quorum system -based neighborhood discovery protocol, which operates on channels having different priorities, on the other hand, we perform an analysis of the effect of asynchronism on the proposed protocol. We analyze the behavior of the protocol in terms of rendezvous opportunities, time-to-rendezvous, and the measured error margins for both, for different asynchronous offsets. We show that an asynchronism can bring noticeable profits over the slot synchronized case.

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

“…In the mT‐GQS scheme each frame of the CH sequence consists of ( n +1) 2 slots used to assign n ranked channels. The mT‐GQS adopts a nested mirror TQS selected in a grid array for mapping n ≥3 channels into the frame time slots of the CH sequence.…”

“…On the other hand, when n ≤2, it exposes the grid quorum systems similar to NGQFH. However, the criteria for ranking the channels is not mentioned in the work of Romaszko et al Therefore, to compare mT‐GQS with our scheme, we simulate mT‐GQS with a channel ranking based on that is executed at the beginning of the CH. Furthermore, a per‐frame sensing capability is added for checking the availability of channels prior each frame.…”

“…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.…”

“…The channel ordering and quorum selection mechanisms are presented in Sections 4.1 and 4.2, respectively. We evaluate the performance of our proposed schemes in Section 5 and compare them with the performance of the disjoint relaxed difference set (DRDS), enhanced jump‐stay (EJS), mirror torus‐in‐grid quorum system (mT‐GQS), symmetric asynchronous rendezvous CH (SARCH), asynchronous CH sequence (A‐CHS), and NGQFH rendezvous schemes. Finally, we conclude this paper in Section 6.…”