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Weruaga L.,Austrian Academy of Sciences | Kepesi M.,Vienna Telecommunications Research Center
European Signal Processing Conference | Year: 2015

The Chirp transform is a powerful analysis tool for variable frequency signals such as speech. The computational load represents the main limitation of its original formulation, discouraging its use in real-time applications. This paper analyzes a fast implementation, based on performing time-warping on the signal under analysis, combined with the Fast Fourier Transform. The performance of the Fast Chirp transform depends on the one hand on the estimation of the time-warping operation based on the signal characteristics, and, on the other hand on the interpolation technique used for the warping. Observations from the analysis of speech signals support the method and the further lines. © 2004 EUSIPCO.


Casas P.,Vienna Telecommunications Research Center | Schatz R.,Vienna Telecommunications Research Center
Computer Networks | Year: 2014

Cloud-based systems are gaining enormous popularity due to a number of promised benefits, including ease of use in terms of deployment, administration and maintenance, high scalability as well as flexibility to create new services. However, as more personal and business applications migrate to the Cloud, the service quality becomes an important differentiator between providers, specially in the case of mobile operators. Quality of Experience (QoE) as perceived by the end-user has therefore the potential to become the guiding paradigm for managing quality provisioning and applications' design in the Cloud. This paper presents the results of several Cloud QoE studies performed for different Cloud-based services, ranging from services with low requirements in terms of latency and interactivity (e.g., Cloud storage systems), multimedia On-Demand services (e.g., YouTube video streaming), communication and telepresence (e.g., Lync Online videoconferencing) to highly interactive services (e.g., Virtual Cloud Desktop). The results of these studies provide a ground truth basis for developing future Cloud services with QoE requirements, as well as for dimensioning the underlying network provisioning infrastructures, particularly with regard to mobile access technologies. © 2014 American Geophysical Union All Rights Reserved.

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