Cognitive Radio (CR) is considered an intelligent technology. It improves the utilization of the radio spectrum. The increasing number of new devices has resulted in growing congestion of the ISM bands. FCC issued an order only permitting unlicensed users (secondary users) to operate in white space without interfering with licensed users (primary users). Cognitive Radio Networks (CRNs) provides a solution to the problem of additional spectrum requirements by utilizing the spectrum more efficiently. CR is able to sense the spectrum and share the spectrum with unlicensed users. There are number of popular spectrum sensing techniques in CR such as cyclostationary feature detection, energy detection and matched filter detection, which capture the best available spectrum. They use a spectrum dynamically in wireless communication network. A CR with multicarrier technique (OFDM and FBMC) are the next generation of advanced cellular network, which would provide better spectrum utilization and therefore have greater capacity. In this study we have described and reviewed CR technology and its numerous features that may play a very essential role in the field of next generation wireless communication networks.

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Now a day all the telecommunication industries are using fibers for faster data communication and long distance communication. Fibers use light as the information and it is carried over long distances. Optical fiber has large advantages over a copper and co-axial cable because of its lower attenuation and interference. Optical time domain reflectometer (OTDR) is also one of the important devices using in telecommunication industries to characterize an optical fiber. This article deals with the study of long distance backbone single mode fiber and their features are discussed with the use of an OTDR. The results of this article focused on the losses and breaks of the fiber with the events. The Single mode OTDR is used to find the events, losses and breaks of the backbone fiber between the two locations. This work will give a way to study the nature of optical fibers and understand the practical application of optical fiber communication.

Optical fiber communication is the backbone of the entire telecommunication industries in the world. In this work, the real-time backbone long-distance optical fibers (single mode) are tested and analyzed with two different wavelengths (1,310 nm and 1,550 nm) with the help of optical time domain reflectometer. Using these two different wavelengths, how the losses and events of the backbone optical fibers are changing are compared and analyzed. This work will give a way to study the nature of long-distance backbone optical fiber and understand the real-time application of the fiber optic communication.