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frequency-comparison
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Comparison models evaluating countermeasures at Highway-Railway Grade Crossings
, Article ICTIS 2013: Improving Multimodal Transportation Systems - Information, Safety, and Integration - Proceedings of the 2nd International Conference on Transportation Information and Safety ; 2013 , Pages 1934-1945 ; 9780784413036 (ISBN) ; Bagheri, M ; Sharif University of Technology
2013
Abstract
This paper reviews the literature concerning the effectiveness of countermeasures at Highway-Railway Grade Crossings (HRGC). HRGC are considered as the hotspots in railway transportation systems. So far, there has been significant discussion about different types of countermeasure to mitigate the risk of accidents at HRGC. Different approaches have been developed about the effectiveness of the countermeasures including the Before-After and Cross-Sectional. This paper compares all different studies to evaluate the effectiveness of countermeasure in reduction of accident frequency and severity
Spectrum Sensing Algorithm and Implementation for Cognitive Radio Applications
, M.Sc. Thesis Sharif University of Technology ; Fotowat Ahmadi, Ali (Supervisor)
Abstract
The continous growth of wireless networks, the increasing numbers of users and devices, along with the demand for higher data rates have intensified the frequency band limitations as the communication medium. In search for more efficient methods to use this limited resource, the cognitive radio approach that allocates the local unused frequency bands to potential users has attracted considerable attension.
A fundamental and unseperable part of any cognitive radio system is its need to search, detect and understand the surrounding frequency spectrum. Although various methods have been already propose to overcome the challenges of this domain, simpler and more reliable methods are still in...
A fundamental and unseperable part of any cognitive radio system is its need to search, detect and understand the surrounding frequency spectrum. Although various methods have been already propose to overcome the challenges of this domain, simpler and more reliable methods are still in...
A new spectrum sensing method using output analysis of the PFD
, Article IEEE Transactions on Circuits and Systems II: Express Briefs ; Volume 60, Issue 6 , 2013 , Pages 366-370 ; 15497747 (ISSN) ; Fotowat Ahmady, A ; Forooraghi, K ; Atlasbaf, Z ; Sharif University of Technology
2013
Abstract
In this brief, a new blind spectrum sensing method is proposed based on frequency comparison using a phase frequency detector (PFD). The PFD output patterns are utilized in a way to sense the spectrum with no knowledge of incoming signals, noise, or channel parameters. The detection and false alarm error probabilities are analytically calculated for additive white Gaussian noise and sine-wave input and are simulated for different inputs. It is shown that the required detection and false alarm probabilities can be achieved by changing the system parameters. The results show that the proposed method has lower complexity and outperforms the previous single-antenna blind method over flat fading...