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 & Terminal (electronics). The organization has 3473 authors who have published 5208 publications receiving 65429 citations. The organization is also known as: DTAG & German Telecom.

A candidate for the ITU-T 4 kbit/s speech coding standard

Abstract: This paper presents the 4 kbit/s speech coding candidate submitted by AT&T, Conexant, Deutsche Telekom, France Telecom, Matsushita, and NTT for the ITU-T 4 kbit/s selection phase. The algorithm was developed jointly based on the qualification version of Conexant. This paper focuses on the development carried out during the collaboration in order to narrow the gap to the requirements in an attempt to provide toll quality at 4 kbit/s. This objective is currently being verified in independent subjective tests coordinated by ITU-T and carried out in multiple languages. Subjective tests carried out during the development indicate that the collaboration work has been successful in improving the quality, and that meeting a majority of the requirements in the extensive selection phase test is a realistic goal.

Method for the use of a gsm/umts mobile communication network by a user equipment attached to a core network of an evolved packet system (eps) mobile communication network

Abstract: A method for use of a Global System of Mobile Communication (GSM) and Universal Mobile Telecommunication System (UMTS) (GSM/UMTS) mobile communication network by a user equipment attached to a core network of an Evolved Packet System (EPS) mobile communication network, the use of the GSM/UMTS mobile communication network being the result of a fallback operation, includes, prior to an invocation of a service that triggers the fallback operation: performing an updating operation regarding assignment of a Location Area Code (LAC) and/or a serving Mobile Switching Center (MSC) to the user equipment; and/or performing, autonomously by the user equipment, a measurement operation regarding a current General Packet Radio System (GPRS)/EDGE Radio Access Network (GERAN) or UMTS Terrestrial Radio Access Network (UTRAN) (GERAN/UTRAN) radio environment in order to identify potential CSFB target cells of the user equipment.

A Markov Decision Process based flow assignment framework for heterogeneous network access

Abstract: We consider a scenario where devices with multiple networking capabilities access networks with heterogeneous characteristics. In such a setting, we address the problem of efficient utilization of multiple access networks by devices via optimal assignment of traffic flows with given utilities to different networks. We develop and analyze a device middleware functionality that monitors network characteristics and employs a Markov Decision Process (MDP) based control scheme that in conjunction with stochastic characterization of the available bit rate and delay of the networks generates an optimal policy for allocation of flows to different networks. The optimal policy maximizes, under available bit rate and delay constraints on the access networks, a discounted reward which is a function of the flow utilities. The flow assignment policy is periodically updated and is consulted by the flows to dynamically perform network selection during their lifetimes. We perform measurement tests to collect traces of available bit rate and delay characteristics on Ethernet and WLAN networks on a work day in a corporate work environment. We implement our flow assignment framework in ns-2 and simulate the system performance for a set of elastic video-like flows using the collected traces. We demonstrate that the MDP based flow assignment policy leads to significant enhancement in the QoS provisioning (higher rate allocation, lower packet delays and packet loss rates) for the flows and better access network utilization, as compared to policies that allocate flows to different networks using greedy approaches or heuristics like average available bit rate on the networks.

OFDM signals with low crest-factor

Abstract: The crest-factor (CF) of a signal is the ratio of its peak magnitude to its root mean-square (RMS) magnitude. An algorithm for the generation of information carrying OFDM signals with very low CF is presented. Such signals allow for the use of OFDM modulation together with power efficient amplifiers without causing out-of-band energy due to transmitter saturation. Since the complexity of the algorithm is completely located at the transmitter side, the proposed scheme is especially suitable for broadcasting services. The cost for the reduced CF is a certain loss in data rate, which can be varied by a parameter of the method. For example, in the case of only 25 percent loss in data rate a CF lower than 2.11 can be achieved.

Proposal for Components of Method Design Theories

Abstract: Gregor and Jones have proposed components for design theories, building on theory concepts from behavioural sciences and prior publications. Their design theory structure addresses IT artefacts in general, not specific to any type, such as constructs, models, methods or instantiations. Their work is an important contribution to the academic discussion of design theories. The authors are building on this and believe that specialised design theory structures for different types of artefacts further increases utility, usability and acceptance of the components for both academia and practise. They have analysed each of the components published by Gregor and Jones and proposed refinements specific to method design artefacts wherever applicable. For each component, they derive evaluation criteria and present examples of method publications fulfilling the criteria. They argue that by presenting method design theories according to this structure the contribution of method design artefacts to the body of knowledge will increase.