QoS Enhancement Techniques for Efficient VoIP Performance in Cognitive Radio Network

VoIP service demands strong QoS support for enhanced call quality and increased user satisfaction. Deploying VoIP in opportunistic communication models like cognitive radio requires thorough analysis of the factors involved in design and implementation. The objective of this paper is to implement VoIP successfully over a cognitive radio network and maintain the call quality at an acceptable limit. Initially, a model of VoIP is built over cognitive radio network using OPNET Modeler 16.0.A. The QoS parameters of delay, jitter and packet loss are analyzed over a basic cognitive radio cycle in the developed model with respect to a single channel. Modifications are proposed in the cognitive radio cycle for improvement in call quality and gain in throughput. Extensive simulation studies reflect overall QoS enhancement after application of the modified cycle. The proposed approach is further enhanced by modifying the VoIP parameters that result in high quality VoIP calls as witnessed from the simulation results. The work is extended in the domain of multiple channels in CRN and an adaptive strategy is introduced in the enhanced version of the proposed algorithm that results in further increase in VoIP call quality. Mathematical analysis of the algorithms provides an outline of optimal selection of related parameters. Finally, a new QoS parameter, cog_cap is designed that denotes the cognitive capacity of VoIP calls. Analysis of cog_cap for the adaptive algorithm indicates high cognitive capability of VoIP calls thereby proving the efficiency of the proposed technique.