Design and Implementation of VoIP Based Two-Tier Cognitive Radio Network for Improved Spectrum Utilization

Cognitive radio networks (CRN) have paved the way toward the increase in spectrum utilization through opportunistic usage of available idle spectrum bands. However, its capacity is bounded by various factors, including channel characteristics, licensed user behavior, application requirements, etc. Currently, a fixed upper bound of the system capacity in CRN limits further progress in research in this domain. The work in this paper aims to solve this problem by introducing the concept of 'two-tier CRN' that not only increases overall system capacity but also allows the system to host diverse applications, thereby initiating a new direction of future research in this discipline. This paper provides the novel design approach for VoIP based two-tier CRN with every detail of formulation of the framework. The complex interaction among primary and secondary users in the proposed system is studied extensively in mathematical, simulation, and Markov models. Performance evaluation confirms 300% improvement in link utilization and, hence, higher network throughput in a two-tier CRN as compared with a basic one-tier CRN. Finally, the practical significance of the designed network is established by successfully implementing it in a test bed based disaster management system.