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Mathematical Problems in Engineering
Volume 2014, Article ID 926709, 15 pages
http://dx.doi.org/10.1155/2014/926709
Research Article

Fuzzy Based PC-PUSH in CR-MANETs

1UTM-MIMOS Center of Excellence, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia
2Department of Electrical Engineering, Faculty of Engineering, Islamic Azad University, Yasuj Branch, Yasuj, Kohgiluyeh and Boyer-Ahmad Province 7591483587, Iran
3Department of Mathematics, Faculty of Science, Islamic Azad University, Yasuj Branch, Yasuj, Kohgiluyeh and Boyer-Ahmad Province 7591483587, Iran
4Department of Electrical Engineering, University of North Dakota, Grand Forks, ND 58202, USA

Received 29 August 2014; Accepted 22 October 2014; Published 26 November 2014

Academic Editor: Ezzat G. Bakhoum

Copyright © 2014 S. Nejatian et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

In cognitive radio (CR), the secondary user (SU) needs to hand off its ongoing communication to an idle channel in order to avoid interference to the primary user (PU). Spectrum hand off issue becomes challenging in CR mobile ad hoc networks (CR-MANETs) because of the uncertainty in spectrum availability, broad range of spectrum bands and lack of central entity. The purpose of this study is to design a unified spectrum handoff (USH) scheme for CR-MANETs that considers the spectrum heterogeneity and its availability over time and space. A local flow hand off is performed when spectrum hand off cannot be carried out due to the SUs mobility. To improve further USH, preemptive unified spectrum handoff (PUSH) algorithm is proposed in which two different preemptive hand off threshold regions are defined. The PUSH algorithm also predicts the cognitive link availability considering the PU interference boundary. Although the PUSH scheme improves the hand off performance, the number of spectrum hand offs due to the PU activity should be reduced in this scheme. Therefore, the PC-PUSH (Power Controller-PUSH) scheme is proposed in which the fuzzy logic is used to improve the PUSH in terms of the number of spectrum handoffs because of the PU activity. The PC-PUSH decreases the interference to the PUs, while reducing the number of spectrum handoffs. The results show that the proposed scheme improves the link maintenance probability, decreases the hand off delay, and reduces the number of spectrum handoffs.