Deutsche Telekom

About: Deutsche Telekom is a company organization based out in Welwyn Garden City, United Kingdom. It is known for research contribution in the topics: Telecommunications network & Signal. The organization has 3473 authors who have published 5208 publications receiving 65429 citations. The organization is also known as: DTAG & German Telecom.

Adapting Brillouin spectrum for slow light delays

Abstract: Described is a simple method to adapt Brillouin spectrum properties such as slope, bandwidth and gain for stimulated Brillouin scattering based slow light systems and other applications. As an example, enhancement of time delay at constant gain and pump power owing to an increased Brillouin slope, is presented.

Method and apparatus for assessing the quality of a video signal during encoding and transmission of the video signal

Abstract: A method for assessing the quality of a transmitted video signal sequence at the receiver side includes the steps of: capturing the received input video bit stream prior to decoding and supplying it to a video bit stream analyzer; extracting, during a measurement time window, one or more features from the captured packet headers by the bit stream analyzer, without analyzing or decoding the packet payload; computing from the one or more features, a single parameter, xwpSEQ, representing an estimate of the spatio-temporal extent of the signal degradation due to packet-loss; supplying the determined parameter to a quality estimation module; and calculating, by the quality estimation module, a quality measure due to packet loss (Q trans ) based on the single parameter representing the estimate of the spatio-temporal extent of the signal degradation, xwpSEQ, due to packet-loss and based on video resolution information and employed video codec

Towards an interchange format for spatial audio scenes

Abstract: This extended abstract outlines a proposal for an ICMC panel discussion with the intention to set on the development of a file format to create, store and share spatial audio scenes across 2D/3D audio applications and concert venues. This discussion shall include composers, sonic artists, researchers and developers in order to make such a format widely acceptable.

Influence of a 902.4 MHz GSM signal on the human visual system: investigation of the discrimination threshold.

Abstract: The proximity of a mobile phone to the human eye raises the question as to whether radiofrequency (RF) electromagnetic fields (EMF) affect the visual system. A basic characteristic of the human eye is its light sensitivity, making the visual discrimination threshold (VDThr) a suitable parameter for the investigation of potential effects of RF exposure on the eye. The VDThr was measured for 33 subjects under standardized conditions. Each subject took part in two experiments (RF-exposure and sham-exposure experiment) on different days. In each experiment, the VDThr was measured continuously in time intervals of about 10 s for two periods of 30 min, having a break of 5 min in between. The sequence of the two experiments was randomized, and the study was single blinded. During the RF exposure, a GSM signal of 902.4 MHz (pulsed with 217 Hz) was applied to the subjects. The power flux density of the electromagnetic field at the subject location (in the absence of the subject) was 1 W/m2, and numerical dosimetry calculations determined corresponding maximum local averaged specific absorption rate (SAR) values in the retina of SAR1 g = 0.007 W/kg and SAR10 g = 0.003 W/kg. No statistically significant differences in the VDThr were found in comparing the data obtained for RF exposure with those for sham exposure. Bioelectromagnetics 28:648–654, 2007. © 2007 Wiley-Liss, Inc.

Towards heterogeneous network convergence: policies and middleware architecture for efficient flow assignment, rate allocation and rate control for multimedia applications

Abstract: The convergence in access networks brings forth the challenge of resource allocation for applications with varying utilities over networks with time-varying and heterogeneous characteristics. Owing to an ever increasing demand and popularity, multimedia applications have been a key driving force behind the efforts targeted towards architectures, industrial standards, and polices for convergence. Multimedia applications use protocols and transport dynamics that constrain the manner in which these applications can utilize access networks. In this work, we propose middleware architecture and policies that target optimal rate allocation for multimedia applications by monitoring and stochastically modeling the variation in characteristics of the access networks, using the utilities of the media application when known, and accounting for the constraints imposed by application specific transport mechanisms. The proposed measures leverage our optimal rate allocation, rate control, and interface assignment techniques [17, 6, 24] to achieve enhanced multimedia performance and efficient utilization of the access networks.