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.

Synchronization for systems with antenna diversity

Abstract: This paper deals with the synchronization of systems with frequency domain signal processing and antenna diversity. The results can be applied for both, single carrier transmission with frequency domain equalization (FDE) and orthogonal frequency division multiplexing (OFDM). For the considered systems, carrier frequency and temporal position of the FFT (fast Fourier transform) window have to be synchronized. A synchronization concept for systems with antenna diversity is presented which uses one pilot FFT symbol per transmission frame. The pilot FFT symbol consists of two periods of a chirp signal.

RECODIS: Resilient Communication Services Protecting End-user Applications from Disaster-based Failures

Abstract: Disaster-based failures can seriously disrupt any communication network, making its services unavailable. Such disruptions may be caused by natural disasters, technology-related failures, or malicious attacks, and they are observably increasing in number, intensity and scale. When network services that are a part of critical infrastructure become unavailable, commercial and/or societal problems are inevitable. The issue of limiting the impact of disaster-based failures needs to be urgently addressed due to the lack of suitable mechanisms deployed in the current networks.

Diversity and equalization in frequency domain a robust and flexible receiver technology for broadband mobile communication systems

Abstract: A new receiver structure for broadband mobile communication systems is presented. Signals with block oriented single-carrier modulation are processed in frequency domain. By using a combination of diversity and equalization, an excellent receiver performance can be achieved even for time-variant and frequency-selective radio channels.

Transmission of 200 G PDM-CSRZ-QPSK and PDM-16 QAM With a SE of 4 b/s/Hz

Abstract: We have realized the first field transmission of 8 × 216.8-Gb/s Nyquist wavelength-division-multiplexing (N-WDM) signals over 1750-km G.652 fiber consisting of 950-km real and 800-km lab fibers with erbium-doped fiber amplifier (EDFA)-only amplification. The average loss per span is 21.6 dB. Each channel is modulated with 54.2-Gbaud (216.8-Gb/s) polarization-division-multiplexing carrier-suppressed return-to-zero quadrature-phase-shift-keying (PDM-CSRZ-QPSK) data on a 50-GHz grid giving a record spectral efficiency (SE) of 4 b/s/Hz. Digital post filtering and 1-bit maximum likelihood sequence estimation (MLSE) are introduced into the offline digital signal processing (DSP) at the receiver to suppress noise, linear crosstalk and filtering effects. We have also investigated the co-transmission of 200 G PDM-CSRZ-QPSK and 200 G PDM 16-ary quadrature-amplitude-modulation (PDM-16 QAM) signals on a 50-GHz grid, and found that PDM-CSRZ-QPSK signals have better bit-error-rate (BER) performance for both back-to-back and 700-km transmission cases. Meanwhile, PDM-16 QAM signals are subject to larger crosstalk from the neighboring Nyquist QPSK channels.

How to turn a GSM SIM into a web server

Abstract: We describe the WebSIM, an approach that integrates GSM SIMs into the Internet. The underlying idea is to implement a Web Server inside a SIM, and to allow for transparent access to it from the Internet.