| Summary: | Cognitive Radio (CR) networks provide a novel approach to address the spectrum scarcity and spectrum inefficiency issues in wireless networks. The main objective of this research is to investigate the challenges, provide solutions, and evaluate the performance of four different types of CR Networks; Cognitive Radio Ad-Hoc Networks (CRAHNs), Cognitive Radio enabled Sensor Networks (CSNs), Cognitive Radio enabled AMI (CR-AMI) Networks, and Cognitive Femtocell Networks. My research is focusing on developing novel solutions, algorithms, and protocol enhancements for different layers of the protocol stack for CR networks. For CRAHNs, a Spectrum Aggregation-based Cooperative Routing Protocol (SACRP) is proposed. The primary objective of SACRP is to provide higher energy efficiency, improve throughput, and reduce network delay for CRAHNs. In this regard, two different classes of routing protocols are proposed as; Class A for achieving higher energy efficiency and throughput, and Class B for reducing end-to-end latency. Based on stochastic geometry approach, A comprehensive analytical model is built for the proposed protocol. Besides, the proposed protocol is also compared with the state of the art cooperative and non-cooperative routing algorithms with spectrum aggregation. On the other hand, CR is expected to play a vital role in smart grid networks. Cognitive Sensor Networks (CSNs) can e effectively address the unique challenges of WSNs in smart grid. Against this background, an energy ecient and reliable Medium Access Control (MAC) protocol is designed for CSNs. The proposed MAC protocol, termed as CRB-MAC, can provide high energy eciency and reliability. In addition, CRB-MAC explicitly accounts for the peculiarities of a CR environment, which provides a viable solution for CSNs. As an integral component of the smart grid ecosystem, Advanced Metering Infrastructure (AMI) networks are practically deployed as a static multi-hop wireless mesh network. It is expected that the use of cognitive radio (CR) technology for AMI networks will be indispensable in near future. In this respect, a new RPL-based routing protocol is proposed for cognitive radio enabled AMI (CR-AMI) networks. This protocol utilizes a global optimization algorithm to select the best route from the whole network. In addition, the proposed routing protocol explicitly protects primary (licensed) users while meeting the utility requirements of the secondary network. The proposed protocol enhances the quality of service (QoS) of the existing RPL-based routing protocols for CR-enabled AMI networks. In heterogeneous networks (HetNets), Cognitive femtocells provide low-power, low-cost, and short-range wireless broadband access, which achieve higher network capacity and spectrum efficiency. Based on a stochastic geometry approach, the rate coverage of two-tier HetNets with cognitive femtocells is analysed. The closed-form expressions for downlink rate coverage of both networks are derived. Moreover, the impact of frequency reuse on the rate coverage in HetNets is evaluated. At last, according to the overall picture of the research conducted, the main conclusions together with some directions for the future work are presented.
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