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 & Terminal (electronics). The organization has 3473 authors who have published 5208 publications receiving 65429 citations. The organization is also known as: DTAG & German Telecom.

A dynamic impairment-aware networking solution for transparent mesh optical networks

Abstract: Core networks of the future will have a translucent and eventually transparent optical structure. Ultra-high-speed end-to-end connectivity with high quality of service and high reliability will be realized through the exploitation of optimized protocols and lightpath routing algorithms. These algorithms will complement a flexible control and management plane integrated in the proposed solution. Physical layer impairments and optical performance are monitored and incorporated in impairment-aware lightpath routing algorithms. These algorithms will be integrated into a novel dynamic network planning tool that will consider dynamic traffic characteristics, a reconfigurable optical layer, and varying physical impairment and component characteristics. The network planning tool along with extended control planes will make it possible to realize the vision of optical transparency. This article presents a novel framework that addresses dynamic cross-layer network planning and optimization while considering the development of a future transport network infrastructure.

Enabling Secure Secret Sharing in Distributed Online Social Networks

Abstract: We study a new application of threshold-based secret sharing in a distributed online social network (DOSN), where users need a means to back up and recover their private keys in a network of untrusted servers. Using a simple threshold-based secret sharing in such an environment is insufficiently secured since delegates keeping the secret shares may collude to steal the user's private keys. To mitigate this problem, we propose using different techniques to improve the system security: by selecting only the most reliable delegates for keeping these shares and further by encrypting the shares with passwords. We develop a mechanism to select the most reliable delegates based on an effective trust measure. Specifically, relationships among the secret owner, delegate candidates and their related friends are used to estimate the trustworthiness of a delegate. This trust measure minimizes the likelihood of the secret being stolen by an adversary and is shown to be effective against various collusive attacks. Extensive simulations show that the proposed trust-based delegate selection performs very well in highly vulnerable environments where the adversary controls many nodes with different distributions and even with spreading of infections in the network. In fact, the number of keys lost is very low under extremely pessimistic assumptions of the adversary model.

Device for Generating and Modulating a High-Frequency Signal

Abstract: A device and method involving a plurality of lasers for generating and modulating a tunable, high-frequency signal for a wireless communication system, including an optical waveguide, may be produced using standard components of optical communication technology. A signal source may be provided which generates an optical signal and is disposed on one side of the optical waveguide. At least one means is provided for generating harmonic waves of this signal, which propagate as frequency mix in the optical waveguide. Two pump lasers are provided for the injection of pump waves on an opposite side of the optical waveguide, which are adapted so that together they amplify two harmonic waves of the frequency mix by stimulated Brillouin scattering. The rest of the harmonic waves are attenuated by damping in the optical waveguide. The two amplified harmonic waves are superposed in a photo element in heterodyne fashion and generate the RF signal.

Method and System for Providing and Reconstructing a Photorealistic Three-Dimensional Environment

Abstract: The present invention relates to a method and system for providing and reconstructing a photorealistic environment, by integrating a virtual item into it, comprising: (a) a dedicated marker, placed in a predefined location within an environment, in which a virtual item has to be integrated, for enabling determining the desired location of said virtual item within said environment; (b) a conventional camera for taking a picture or shooting a video clip of said environment, in which said marker was placed, and then providing a corresponding images of said environment; and (c) one or more servers for receiving said corresponding image of said environment from said camera, processing it, and outputting a photorealistic image that contains said virtual item integrated within it, comprising: (c.1.) a composer for composing a photorealistic image from said corresponding image of said environment; (c.2.) an image processing unit for processing said corresponding image and for determining the location of said marker within said environment; (c.3.) a configuration database for storing configurations and other data; and (c.4.) an image rendering unit for reconstructing the photorealistic image by integrating said virtual item into said predefined location of the photographed environment, wherein said marker is located.

Planung und Entwicklung von Tests und Fragebogen

Abstract: Dieses Kapitel bietet einen Uberblick uber den Prozess der Entstehung eines Tests oder Fragebogens, angefangen von der ersten Testplanung, uber die Testentwicklung bis hin zur Erstellung und einer vorlaufigen Erprobung der Testvorversion mit dem Ziel der Revision zur endgultigen Version. Es soll verdeutlichen, welche Aspekte bei der Konstruktion eines Testverfahrens zu berucksichtigen sind und dass ein psychometrischer Test mehr ist als eine Ansammlung von Aufgaben oder Fragen. Der Unterschied besteht darin, dass psychometrische Tests psychische Merkmale quantitativ auf der Basis von Testtheorien erfassen und somit eine metrisch vergleichende Diagnostik ermoglichen.