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.

Spatio-temporal network anomaly detection by assessing deviations of empirical measures

Abstract: We introduce an Internet traffic anomaly detection mechanism based on large deviations results for empirical measures. Using past traffic traces we characterize network traffic during various time-of-day intervals, assuming that it is anomaly-free. We present two different approaches to characterize traffic: (i) a model-free approach based on the method of types and Sanov's theorem, and (ii) a model-based approach modeling traffic using a Markov modulated process. Using these characterizations as a reference we continuously monitor traffic and employ large deviations and decision theory results to ldquocomparerdquo the empirical measure of the monitored traffic with the corresponding reference characterization, thus, identifying traffic anomalies in real-time. Our experimental results show that applying our methodology (even short-lived) anomalies are identified within a small number of observations. Throughout, we compare the two approaches presenting their advantages and disadvantages to identify and classify temporal network anomalies. We also demonstrate how our framework can be used to monitor traffic from multiple network elements in order to identify both spatial and temporal anomalies. We validate our techniques by analyzing real traffic traces with time-stamped anomalies.

Intuitive use of user interfaces: defining a vague concept

Abstract: In this paper we present a general definition of the concept 'intuitive use of user interfaces' on the basis of our current interdisciplinary work. 'Intuitive use' is regarded as a characteristic of human-machine systems. It refers to a special kind of interaction process between users and technical systems that use the users' intuition. The main part of the paper deals with central aspects of this definition in detail and discusses pre-conditions and restrictions of the use of the concept. The main aspects that we discuss are the design of technical systems, application and non-conscious use of previous knowledge, intuition as a non-conscious process, interaction, and effectiveness. We complement this discussion by addressing the relationship between aesthetics and intuitive use.

The dependence of electromagnetic energy absorption upon human-head modeling at 1800 MHz

Abstract: The authors of a previously published paper on the dependence of electromagnetic (EM) energy absorption concluded that homogeneous modeling of the human head is suited for assessing the spatial-peak absorption for transmitters operating at 900 MHz or below. Additional studies became necessary for the frequency bands utilized by new mobile communications systems (i.e., 1.5 and 2.5 GHz) since some peripheral tissue layers have a thickness of the range of /spl lambda//4-/spl lambda//2. The results of the simulations combined with worst-case considerations confirmed the anticipated and more complex relationship between absorption and anatomical details at these higher frequencies. Nevertheless, a homogeneous representation of the head is suited for assessing the maximum specific absorption rate (SAR) in the head of the user of mobile telecommunication equipment (MTE) if the appropriate dielectric parameters are chosen.