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.

Improving internet-wide routing protocols convergence with MRPC timers

Abstract: The behavior of routing protocols during convergence is critical as it impacts end-to-end performance. Network convergence is particularly important in BGP, the current interdomain routing protocol. In order to decrease the amount of exchanged routing messages and transient routes, BGP routers rely on MRAI timers and route flap damping. These timers are intended to limit the exchange of transient routing messages. In practice, these timers have been shown to be partly ineffective at improving convergence, making it even slower in some situations.In this paper, we propose to add a timer mechanism to routing protocols, that enforces an ordering of the routing messages such that path exploration is drastically reduced while controlling convergence time. Our approach is based on known results in generalized path algorithms and endomorphism semi-rings. Our timers, called MRPC (metrics and routing policies compliant), are set independently by each router and depend only on the metrics of the routes received by the router as well as the routing policies of the router. No sharing of information about routing policies between neighboring ASs is required by our solution. Similarly to the case of routing policies that may lead to BGP convergence problems, arbitrary routing policies can also make it impossible to enforce an ordering of the messages that will prevent path exploration to occur. We explain under which conditions path exploration can be avoided with our timers, and provide simulations to understand how they compare to MRAI.

FAST: Flexible and Low-latency State Transfer in Mobile Edge Computing

Abstract: It is vital for Tactile Internet to constantly maintain a low-latency control loop between sensors, actuators, and their controlling software applications. Mobile Edge Computing (MEC) is an essential technology that brings the elasticity of cloud computing to run controlling applications at a close proximity to controlled objects, thus reducing latency. To support the mobility of the objects, the underlying network has to be capable of migrating MEC applications seamlessly to guarantee the close proximity. However, it is challenging to migrate application states quickly and flexibly without interrupting the control loop. We propose FAST, a flexible scheme for direct and low-latency state transfer leveraging Software-Defined Networking (SDN). Evaluation results show that compared to state of the art, FAST reduces the service migration time by 80%.

Experiences with BOWL: managing an outdoor WiFi network (or how to keep both internet users and researchers happy?)

Abstract: The Berlin Open Wireless Lab (BOWL) project at Technische Universitat Berlin (TUB) maintains an outdoor WiFi network which is used both for Internet access and as a testbed for wireless research. From the very beginning of the BOWL project, we experienced several development and operations challenges to keep Internet users and researchers happy. Development challenges included allowing multiple researchers with very different requirements to run experiments in the network while maintaining reliable Internet access. On the operations side, one of the recent issues we faced was authentication of users from different domains, which required us to integrate with various external authentication services. In this paper, we present our experience in handling these challenges on both development and operations sides and the lessons we learned.

Mechanical stabilisation and tuning method for photon crystal filter used in optical fibre communications

Abstract: The method involves filling the hollow spaces in the filter, e.g. which is structured as a photon crystal, with optically transparent material of adjustable refractive index. The filled filter is subjected to an electrical field of variable field strength. The optical characteristics, e.g. the refractive index for transmitted and reflected light in the crystal's hollow chamber, fine tuning of the transmitter amplitude and fine tuning of the light phase shift are adjusted by varying the field strength of the electric field.

Method for billing internet transactions via mobile radio telephone service

Abstract: The invention relates to a method for billing internet transactions via mobile radio telephone service. By using WAP (Wireless Application Protocol), it is possible to select and, optionally, reserve goods and services (information, tickets, CD"s, hotel rooms, etc ) sold via the internet. When the customer decides to purchase the good or service, he or she conducts a payment transaction from the mobile radio telephone device. According to the invention, the customer data required for conducting a payment transaction is centrally maintained in a database of a payment gateway.