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.

Efficient massive multichannel active noise control using wave-domain adaptive filtering

Abstract: Multichannel acoustic active noise control (ANC) systems are increasingly being developed in order to enlarge the spatial extend of the quiet zone. This paper discusses the physical background of an ideal ANC system for noise sources outside and within the ANC system. This idealized system can be realized reasonably well with a high number of channels (massive multichannel ANC). It is shown that the typically applied adaptation algorithms have fundamental limitations in the context of massive multichannel ANC. The versatile framework of eigenspace and wave-domain adaptive filtering is proposed as solution to these. Simulation of a massive multichannel ANC system illustrates the successful application of the proposed concepts.

Comparison of Modulation Schemes for 10.7 Gb/s Transmission Over Large-Core 1 mm PMMA Polymer Optical Fiber

Abstract: The authors give an overview of experimental results on 10.7 Gb/s over large-core 1 mm polymethyl-methacrylate (PMMA) polymer optical fiber (POF). The comparison starts with simple non-return-to-zero (NRZ) transmission without equalization. Next, measurement results with feed-forward-, decision -feedback equalization (FFE, DFE) and maximum likelihood sequence estimation (MLSE) are presented. Finally, experimental results with more advanced modulation schemes like pulse amplitude modulation (PAM) and discrete multitone (DMT) modulation are investigated. The experiments were carried out with a Vertical-Cavity Surface-Emitting Laser (VCSEL) at 0 dBm to comply with consumer eye-safety regulation or with a 10 mW laser diode (LD) that could be used in active optical cables.

Method and system for user authentication by means of a cellular mobile radio network

Abstract: The invention relates to a method and system for authentication of a user ( 11 ) at an access device by means of a cellular mobile radio network ( 17 ). The access device gives access to a facility or a service different from the mobile radio network ( 17 ). The cellular mobile radio network ( 17 ) comprises a base station ( 12 ) defining a mobile radio cell ( 16 ) with a unique identifier. A mobile radio terminal ( 14 ) having a unique identifier books into the mobile radio network ( 17 ) via said base station ( 12 ), and the authentication is carried out by means of the identifier of the mobile radio cell ( 16 ) and the identifier of the mobile radio terminal ( 14 ). The base station ( 12 ) is arranged at the location of the access device so that the access device has its own mobile radio cell ( 16 ) serviced by the base station ( 12 ), this mobile radio cell ( 16 ) defining an authentication cell ( 16 ) of the mobile radio network ( 17 ). The mobile radio terminal ( 14 ) is caused to book into the mobile radio network ( 17 ) via said base station ( 12 ) of said authentication cell ( 16 ) for the purpose of authentication at the access device whereupon the identifiers are sent to an authentication entity ( 18 ) that checks whether the user ( 11 ) is permitted to get access at the access device. Access is granted or denied depending on the permission of the user ( 11 ).

Traffic engineering using segment routing and considering requirements of a carrier IP network

Abstract: Internet Service Providers (ISPs) are challenged by increasing traffic demands. Advanced Traffic Engineering (TE) is one way to overcome this challenge. Segment Routing (SR) is a relatively new approach for TE. To decide whether SR is a good approach for deployment in carrier IP backbone networks, it has to show its benefits in real-world scenarios and still needs to be feasible from the network operation and management point of view. In this paper, we analyze traffic data from a European tier one backbone network from 2011 to 2015. The total traffic increases significantly throughout that period. We analyze geographic differences to select representative traffic peak times as reference scenarios for an evaluation of TE using SR for real-world topologies and traffic demands. Finally, we extend existing SR formulations to consider requirements from network operation and management. Our evaluation results show that SR yields close to optimal results while still being deployable with reasonable effort.

Semi-automatic zooming for mobile map navigation

Abstract: In this paper we present a novel interface for mobile map navigation based on Semi-Automatic Zooming (SAZ). SAZ gives the user the ability to manually control the zoom level of an SDAZ interface, while retaining the automatic zooming characteristics of that interface at times when the user is not explicitly controlling the zoom level. In a user study conducted using a realistic mobile map with a wide scale space, we compare SAZ with existing map interface techniques, multi-touch and Speed-Dependent Automatic Zooming (SDAZ). We extend a dynamic state-space model for Speed-Dependent Automatic Zooming (SDAZ) to accept 2D tilt input for scroll rate and zoom level control and implement a dynamically zoomable map view with access to high-resolution map material for use in our study. The study reveals that SAZ performs significantly better than SDAZ and that SAZ is comparable in performance and usability to a standard multi-touch map interface. Furthermore, the study shows that SAZ could serve as an alternative to multi-touch as input technique for mobile map interfaces.