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.

Laser diodes with integrated spot-size transformer as low-cost optical transmitter elements for telecommunications

Abstract: We have realized laser diodes with integrated spot-size transformer to achieve a high-coupling efficiency to a standard single-mode fiber (SMF) without microoptical elements. A coupling loss of about 1 dB has been achieved with tolerances of 12 /spl mu/m in both vertical and horizontal direction. We have fabricated both distributed-feedback (DFB) and Fabry-Perot (FP)-type lasers. In the case of the FP lasers the longitudinal single-mode emission was stabilized by means of an external fiber Bragg-grating which was directly butt-coupled to the laser. We have experimentally and theoretically investigated the optical and electrical properties of the devices using a transmission line model.

Location prediction for large scale urban vehicular mobility

Abstract: Knowledge of where vehicles will be in near future helps users in daily planning, traffic monitors in vehicles scheduling, advertisers in fixed point advertising, and especially helps in communication network source provisioning. In this paper, we analyze the predictability of taxi mobility based on their locations and time period records and we present a prediction method of taxis for their next locations in 15 seconds using Markov predictor. The historical location trace of each taxi is used to train the transition probability matrix of next location for our predictor, and we use 3 different scenarios to predict. Based on records from over 2,000 taxis in Shanghai, and over 14,000 taxis in Beijing, we are able to predict the next vehicular location with an accuracy of 82%.

Method of and system for measuring quality of audio and video bit stream transmissions over a transmission chain

Abstract: A method for measuring quality of packetized audio and video transmission over a transmission chain includes: providing one or more measurement detectors along the transmission chain; detecting, by the one or more measurement detectors, loss of bit stream packets at one or more measurement points; determining the unique identifier for each detected lost packet; sending, by the one or more measurement detectors, a list of lost packet identifiers to a central monitoring system; constructing, by the central monitoring system, a simulated stream for each measurement point based on a stored error-free stream and the received lost packet identifiers; and evaluating the simulated stream for deriving a quality score for each measurement point.

Method for generating and distributing unpersonalised and confidential electronic keys

Abstract: Key carriers are generated by an appropriate authority in a secure environment and personalized and included secret and producer seal. You should be able to be produced in unlimited number in advance and distributed without the certificates in the personalization to write with the mystery together in one key carrier and without the identity of the owner or later use known or defined. The key handles with a visible reference identification, a manufacturer's PIN and a key pre-produced one kept secret component in the especially protected area, and a generator seal and a reference information in the less protected area contains. The fixed associated public key component is stored with a second unequal reference information at the output instance. Only when assigning the key to a user changes the manufacturer PIN in an individual PIN and has its identity to the personalization instance from which manages both references, personalized public key component, sealed, enters into the key directory and confirms the user. The key produced by this process are universally applicable.

Privacy-aware and energy-efficient geofencing through reverse cellular positioning

Abstract: Location-based services (LBSs) are gaining a significant increase in popularity these days and are about to take the next step towards proactive LBSs In comparison to conventional LBSs, their proactive variant makes use of continuous position tracking to detect changes in spatial relationships between a user and surrounding objects and proactively perform according actions, a concept that is also known as geofencing But tracking so far also results in tremendous battery drain in mobile devices and may conceal serious privacy issues for their users which can be seen as the biggest inhibitors to making proactive LBSs available for the masses This paper proposes a method to detect the relationship between a user and a target location without significant overhead in power consumption by exploiting signals broadcasted from cellular radio network infrastructure at that location In opposite to conventional cellular location determination mechanisms like WiFi or Cell-Id positioning where a radio beacon will be resolved as soon as it is detected, our proposal has to resolve only one request initially This not only saves energy, but also preserves the user's privacy since no consecutive requests have to be sent to a location lookup server, for translating radio beacons into locations Instead, the radio beacons that can be detected at the target location will be queried once and afterwards only compared to the currently received cellular radio signals In some outlying areas only rudimentary cellular coverage might be provided, which leads to inaccurate positioning In that case, the method can still serve as a basis mechanism to further improve accuracy by shortly utilizing additional positioning methods like GPS Relying on an almost global wireless data connectivity, smartphones can access data from the internet almost anywhere, which allows this approach to be broadly available as an energy-efficient and privacy-aware alternative to conventional cellular location determination