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.

Bandwidth Efficient String Reconciliation Using Puzzles

Abstract: Of considerable interest in recent years has been the problem of exchanging correlated data with minimum communication. We thus consider the problem of exchanging two similar strings held by different hosts. Our approach involves transforming a string into a multiset of substrings that are reconciled efficiently using known multiset reconciliation algorithms, and then put back together on a remote host using tools from graph theory. We present analyses, experiments, and results to show that the communication complexity of our approach for high-entropy data compares favorably to existing algorithms including rsync, a widely-used string reconciliation engine. We also quantify the trade-off between communication and the computation complexity of our approach

Reliable Wireless Broadcasting with Near-Zero Feedback

Abstract: We examine the problem of minimizing feedbacks in reliable wireless broadcasting, by pairing rateless coding with extreme value theory. Our key observation is that, in a broadcast environment, this problem resolves into estimating the maximum number of packets dropped among many receivers rather than for each individual receiver. With rateless codes, this estimation relates to the number of redundant transmissions needed at the source in order for all receivers to correctly decode a message with high probability. We develop and analyze two new data dissemination protocols, called Random Sampling (RS) and Full Sampling with Limited Feedback (FSLF), based on the moment and maximum likelihood estimators in extreme value theory. Both protocols rely on a single-round learning phase, requiring the transmission of a few feedback packets from a small subset of receivers. With fixed overhead, we show that FSLF has the desirable property of becoming more accurate as the receivers's population gets larger. Our protocols are channel agnostic, in that they do not require a-priori knowledge of (i.i.d.) packet loss probabilities, which may vary among receivers. We provide simulations and an improved full-scale implementation of the Rateless Deluge over-the-air programming protocol on sensor motes as a demonstration of the practical benefits of our protocols, which translate into about 30% latency and energy consumption savings.

Efficiency of caches for content distribution on the Internet

Abstract: Traffic engineering and an economical provisioning of bandwidth is crucial for network providers in times of high competition in broadband access networks. We investigate the efficiency of caching as an option to shorten end-to-end paths and delays while at the same time reducing traffic loads. The portion of HTTP based distribution of cacheable content on the Internet is increasing in recent time. In addition, the favourable effect of Zipf-like access pattern on caches is also confirmed for currently most popular web sites with user generated content. Content delivery (CDN) and peer-to-peer (P2P) networks are distributing a major portion of IP traffic with different impact on caching. P2P traffic is subject to long transport paths although appropriate for caching in principle. CDNs are based on server infrastructures allowing for shorter paths on a global scale on top of network provider platforms. We give a brief overview of the options for deploying caches by content and network providers at different points in the interconnection, backbone or aggregation. The main part of the work focuses on the analysis of replacement strategies with regard to Zipf-like and fixed or slowly varying access pattern. A comparative evaluation shows that least recently used (LRU) essentially differs from caching strategies based on access statistics in terms of the achievable hit rates.

5G radio access network architecture based on flexible functional control / user plane splits

Abstract: 5G networks are supposed to offer a high flexibility in a several ways. In this regard, a twofold split of the processing in the radio access network is under discussion: A control plane / user plane split to support the software defined networking principle and a radio protocol stack layer based split to allow a flexible placement of processing functions between a central and distributed units. In this work, the motivation and state of the art for both splits are described including a discussion of the advantages and disadvantages. It is followed by a description of a network architecture allowing a flexible implementation of these splits. This especially focuses on the required interfaces between control and user plane.