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.

Verfahren und Einrichtung zur Anonymisierung von Telekommunikationsvorgängen und -beziehungen bei Telematikanwendungen

Abstract: Beschrieben wird ein Verfahren sowie eine Einrichtung zur Anonymisierung von Telekommunikationsvorgangen und -beziehungen bei Telematikanwendungen, wobei eine logisch zwischen Telekommunikationsnetz und Telematik-Service-Zentrale befindliche Einrichtung gegenuber dem Betreiber/Anbieter von Telematik-Dienstleistungen alle den Endteilnehmer identifizierenden Merkmale aus dem Kommunikationsvorgang entfernt. Sie werden durch eine eindeutige, auserhalb der Einrichtung unbekannte und hinreichend haufig wechselnde temporare Identifikation ersetzt, und fur eine begrenzte Zeit wird die Abbildung der permanenten Identifikation auf die temporare Identifikation gewahrleistet.

On the accuracy of short-term quality models for long-term quality prediction

Abstract: With video services such as HTTP-based adaptive streaming, network congestion may result in quality fluctuations over several minutes. There is therefore a need for estimating the quality of long audiovisual sequences. This can be achieved by using short-term audiovisual quality models, which output quality scores for short periods of time, for instance 10 s. Temporal pooling such as averaging is typically applied on the short-term quality estimates for providing a quality score for a longer time period, for instance three minutes. With this modeling strategy, the performance of the overall quality model can be increased by improving both the short-term quality model and the temporal pooling strategy. However, depending on the temporal pooling strategy, and possibly the targeted test data obtained for long sequences, a small improvement of the short-term quality model may eventually not have any significant impact on the long-term quality estimates. This paper investigates this aspect by comparing the performance results of the combination of six short-term quality models with six different pooling strategies. Results show that the performance of well performing short term models is a good indicator of the performance of the long-term quality models, independently of the pooling strategy.

OFDM and related methods for broadband mobile radio channels

Abstract: A comparison is made of multicarrier and single carrier modulation schemes for radio communication systems. In both schemes, the fast Fourier transform (FFT) and its inverse are utilized. For OFDM (orthogonal frequency division multiplexing), the inverse FFT transforms the complex amplitudes of the individual subcarriers at the transmitter into the time domain. At the receiver, the inverse operation is carried out. For single carrier modulation, the FFT and its inverse are used at the input and output of the frequency domain equalizer in the receiver. Different single carrier and multicarrier transmission systems are simulated with time-variant transfer functions measured with a wideband channel sounder. For OFDM, the individual subcarriers are modulated with fixed and adaptive signal alphabets. In particular, the performance degradation of single carrier and multicarrier transmission due to pilot-aided channel estimation is analyzed.

Authenticating a telecommunication terminal in a telecommunication network

Abstract: A method for authenticating a telecommunications terminal having an identity module includes: storing a first private key, a first public key and a first signature, the first signature being based on signing the first public key using a second private key; generating identity information and a second signature, the second signature being based on signing the identity information using the first private key; transmitting the first public key, the identity information, and the first and second signatures to a server device; verifying, by the server device, the authenticity of the first public key using a second public key; and verifying, by the server device, the authenticity of the identity information using the verified first public key. The identity information includes International Mobile Subscriber Identity (IMSI) information.

Metropolitan Public WiFi Access Based on Broadband Sharing

Abstract: As mobile applications become more pervasive and the demand for affordable mobile broadband Internet access grows, bandwidth sharing solutions via IEEE 802.11-based technology populate the telecommunications market. Many of the existing solutions are based on the willingness of Internet user communities to share their broadband connection at home. However, some other access sharing models have introduce incentives for those users that share their Internet connection. Another aspect that differentiates current solutions is the approach to deploy such a service. In general, these solutions can be grouped in three categories: the ones that follow a guerrilla approach, those that partner with ISPs, and the sharing solutions that originate inside the telcos. These options are compared in this paper from the business and technology angles, discussing the pros and cons of each of them. In addition, a broadband sharing enabling solution, called Extended HotSpots is described. This solution was evaluated during a field trial in the city of Berlin and the results collected are included in this paper.