A Review paper based on spectrum sensing techniques in Cognitive Radio Networks

Natural frequency spectrum is scared resource; the efficient use of it can only accommodate the need of future computing world. But efficient use of it is not possible within the existing system, where the allocation of spectrum is done based on fixed spectrum access (FSA) policy. Many survey shows that it leads to under use of spectrum. For efficient utilization of spectrum innovative techniques is needed. using Dynamic spectrum access (DSA) policy we can exploiting the available spectrum, For given purpose Cognitive radio arises to be a tempting solution to the spectral congestion problem by introducing opportunistic usage of the frequency bands that are not heavily occupied by licensed users. This paper presents the study of different spectrum sensing techniques of cognitive radio networks. As we know Cognitive radio is a form of wireless communication where radio transceiver intelligently detects which spectrums are free which are not. After this it occupies the vacant one while avoiding busy one spectrum. Cognitive radios promote open spectrum allocation which is a clear departure from traditional command and control allocation schemes for radio spectrum usage. In short, they allow the formation of “infrastructure-less” collaborative network clusters—cognitive radio networks. However, how to detect free spectrum we have to use the spectrum sensing techniques, here we are describing all the spectrum sensing techniques and Finally concluded that cooperative sensing is better than Non-Cooperative sensing for primary user (PU) signal with  low SNR value. Keywords- CRN, FSA, PU, DSA, SU, SNR.

Epidemiology of confirmed coronary heart disease among population older than 60 years in rural central India—A community-based cross-sectional study

Background: Three-fifths of total deaths in India are attributed to noncommunicable diseases, and coronary heart disease (CHD) is one of the dominant causes. There are only few studies available in India to find confirmed CHD by pragmatic approach. This study aims to find prevalence of confirmed CHD and its risk factors in rural community of central India. Materials and methods: This was a community-based cross-sectional study during 2013–2014 involving adults ≥60 years from 13 villages in rural central India. We screened CHD on the basis of history and standard 12-lead ECG. Apart from the past documentation of CHD, we diagnosed confirmed CHD in symptomatic patients or with resting ECG changes by means of echocardiography, exercise ECG test or coronary angiography whenever needed. Results: We screened 1190 of 1415 individuals ≥60 years for CHD. Five hundred eighty were men and 610 were women. Diagnosis of CHD was confirmed in 61 individuals (29 men and 32 women). The prevalence of CHD in individuals older than 60 years was 51.3 per 1000 population. Hypertension was the only independent risk factor associated with CHD, whereas association of diabetes mellitus, obesity, socioeconomic status and smoking with CHD was not significant. Conclusion: Prevalence of confirmed CHD has increased in agrarian rural community in central India, which requires further studies to find out causative factors. Keywords: Coronary heart disease, Epidemiology, Rural Indi