AN IMPROVED CHANNEL RANKING ALGORITHM FOR SPECTRUM HANDOFF IN COGNITIVE RADIO AD-HOC NETWORK.

Abstract

The rapid increase in wireless communication technology in the past decade has led to scarcity of spectrum. Thus the world is moving away from fixed Spectrum Access (FSA) techniques to Dynamic Spectrum Access (DSA) techniques. Cognitive Radio (CR) is one of the spectrum access technique that makes use of DSA by allowing Secondary Users (SUs) to make use of the Primary Users (PUs) channels opportunistically. The SUs have to vacate the PUs channels when the PUs arrive on their channels in order to avoid interference with the PUs transmission. The process whereby the SUs switch their communication to another vacant channels when the PUs arrives on their channels is known as spectrum handoff. Finding other vacant channels for the interrupted SUs to continue their transmission is a challenging task. Several researchers have used different technique to select the best channel by considering channel occupancy as a criterion, but these technique still suffer some challenges such as high number of handoff, delay and low throughput. Therefore this paper presents an Improved Channel Ranking Algorithm (ICRA) that rank channel based on channel occupancy and channel signal quality. The channel with the highest rank is selected as the next target channel. Simulation was carried out using Network Simulator (NS) and the results obtained were plotted using MATLAB. The results showed that the ICRA reduced the number of handoff by 14% and 25% compared to Novel Proactive Handoff Scheme (NPHS) and IEEE 802.11 scheme, it also reduced the packet delay by 12% and 34% when compared to the NPHS and IEEE 802.11 scheme. Furthermore, the ICRA increased the throughput by 8% and 97% when compared to the NPHS and the IEEE 802.11 scheme, it also improved the packet delivery ratio by 15% and 96% when compared to the NPHS and IEEE 802.11 scheme