Abstract
Cognitive radio is one of the technologies promoting flexible and efficient use of radio frequency spectrum, thus solving spectrum scarcity problem. Frequency assignment is an integral part of the cognitive radio spectrum management and a critical point of success or failure of the cognitive radio concept. In this paper, cognitive radio frequency assignment with a novel interference weighting and categorization is proposed, as an extension of the solution to the graph coloring problem. In our approach, the edge weights quantifying the interference potential are appended to the conflict graph, co- and adjacent channel interference are treated, and dynamically changing local lists of blocked frequencies are included. We propose the improved cognitive radio saturation metric for the dynamic vertex ordering and to introduce interference categorization which will reduce the communication overhead. Using the proposed model, resource manager can quantify individual interference components, as well as aggregate interference from multiple users, resulting in more knowledgeable frequency decisions. Generalization of the proposed model is suggested. The suggested generalization consists of the selection of the central frequency and optimal bandwidth to be used, according to the user requirements. We have developed interference-sensitive algorithms for minimizing the interference and maximizing the throughput, both in centralized and distributed implementation. The results show significant reduction of the interference, improved spectrum efficiency, and increase in network throughput, comparing to the benchmark algorithms.
Highlights
The future market demand for the wireless broadband services, internet of things, machine to machine communications, and wireless data offload requires the deployment of the generation wireless networks, which will need a rapid and a more flexible access to the radio frequency spectrum
The frequency assignment (FA) ensures that the appropriate frequency is selected to satisfy the requirements of the secondary users (SUs), while enabling an efficient usage of the radio frequency spectrum
The FA is a crucial function that limits the interference between the cognitive radio (CR) devices and primary users (PUs) operating in a heterogeneous and dynamic radio environment
Summary
The future market demand for the wireless broadband services, internet of things, machine to machine communications, and wireless data offload requires the deployment of the generation wireless networks, which will need a rapid and a more flexible access to the radio frequency spectrum. Our work differs from the previous works on the graph coloring-based CR networks FA in several aspects: the level of the interference between the SUs and between the SUs and PUs are numerically quantified using both the continuous and discrete weights; the influence of the cochannel and adjacent channel interference are considered; all individual interference contributions and cumulative interference values are monitored in the course of FA process. The advantages of the proposed interference sensitive FA strategy are numerous It significantly reduces the interference in the CR networks, fully protects the PUs, reduces the frequency reuse distance between the CR users, improves spectrum usage efficiency, and increases the overall networks throughput with the available radio spectrum. This spectrum switching delay includes the time intervals for the spectrum decision process in the base station, signaling for establishing new channels and the RF front-end
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