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Cognitive radio networks (CRN) make use of dynamic spectrum access to communicate opportunistically. Unlicensed users severely affect the spectrum sensing outcomes in CRN. Primary user emulation attack (PUEA) and spectrum sensing data falsification (SSDF) have become a paramount concern in CRNs. It is especially challenging when both masquerading (in the physical layer) and falsification (in the data link layer) occur by providing false spectrum reports. Existing methods to detect such attacks cannot be utilised in scenarios with multi-hop CRN. In this study, to mitigate attack against PUEA and SSDF, a method called optimised sensing and Levenshtein nearest centroid classification (OS-LNCC) for multi-hop CRN is presented. First, a network model for multi-hop CRN is designed. Next, a probable density optimal logical sensing model is designed to alleviate the problems related to falsification of spectrum reports. Here, the falsification of spectrum reports is overcome by exploiting dual factors, that is, probability for false alarm and probability for detection according to the departure rate of primary user (PU). With these dual factors, optimal logical sensing is made, therefore improving the throughput with minimum delay. Finally, each cognitive radio (CR) user evaluates its current sensing information to existing sensing classes through the Levenshtein distance function. Based on quantitative variables, the prediction function of each sensing class is measured using nearest centroid (NC) classifier and the sensing report is classified into either presence or absence of PU. These predictive classes are then integrated at the fusion centre so that robust mitigation against PUEA and SSDF is made. Computer simulation outputs show that OS-LNCC method performs better than the conventional methods using metrics such as sensing delay by 47%, percentage of error in prediction by 46% and throughput by 45%.

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This paper gives a general survey on Crop Field Smart Irrigation Mechanization utilizing web from claiming things. The paper covers details regarding the basics of Internet of Things and also the importance of Agriculture in a country like India. Internet of Things is fundamentally those intercontinental for everyone electronic units through Internet. By this interconnection the devices work in a synchronous way to achieve common goals. It is an evolving technology in the areas of trade, industry, medical and many applications. Many applications of IoT make use of sensors for detecting and activating gadgets helping in sharing of data. Agriculture is one such trade on which the entire nation is dependent. We in brief review the various techniques which will allow the farmers to grow more of their crops and reduce wastage of water by using sensors and automation of the irrigation system. The irrigation of crop fields depends on the data collected by the soil moisture sensors. The review can also be extended by understanding the way light intensity is controlled in greenhouses and also that the farmers can be able to monitor the field conditions from anywhere. This system is very useful in areas with scarcity of water. This sys is 92% more efficient than the conventional approach.

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