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.

Impact of altruism on opportunistic communications

Abstract: Opportunistic networking largely relies on human-carried devices as relays to move data across the network. Human altruistic behavior is an important factor in the feasibility and performance of such a system. In this paper, we study the impact of different altruism distributions on the system throughput and delay of opportunistic communications. We evaluate the system performance by utilizing social network topological models and experimental human mobility traces with different communication patterns. We also discuss several observations from the result of the study. To the best of our knowledge, this is the first study of the impact of altruism on opportunistic communications.

No-reference video quality assessment for SD and HD H.264/AVC sequences based on continuous estimates of packet loss visibility

Abstract: In this paper, a novel method for predicting the visibility of packet losses in SD and HD H.264/AVC video sequences and modeling their impact on perceived quality is proposed. Based on the findings of a new subjective experiment it is initially shown that the classification of packet loss visibility in a binary fashion is not sufficient to model the perceptual degradations caused by the transmission errors. The proposed no-reference algorithm extracts a set of features from the video bit-stream to account for the spatial and temporal characteristics of the video content and the induced distortion due to the network impairments. Subsequently, the visibility of packet losses is predicted in a continuous fashion using Support Vector Regression. Finally, a no-reference bit-stream based video quality assessment model that explicitly employs the predicted packet loss visibility estimates is presented. The evaluation of the proposed model demonstrates that the use of continuous estimates for the visibility of packet losses improves the performance of the video quality assessment model.

A control theoretic approach to noncooperative game design

Abstract: This paper investigates design of noncooperative games from a control theoretic perspective. Pricing mechanisms are used as a design tool to ensure that the Nash equilibrium of a broad class of noncooperative games satisfies certain global objectives such as welfare maximization. The class of games considered provide a theoretical basis for a variety of decentralized resource allocation and control problems including network congestion control, wireless uplink power control, and optical power control. The game design problem is analyzed under full and limited information assumptions for dynamic systems and nonseparable utility functions. Stability properties of the game and pricing dynamics are studied under the assumption of timescale separation and in two separate time-scales. Thus, sufficient conditions are derived, which allow the designer to place the Nash equilibrium solution or to guide the system trajectory to a desired region or point. The obtained results are illustrated with examples.

Performance and Quality-of-Service Analysis of a Live P2P Video Multicast Session on the Internet

Abstract: We evaluate the performance of a large-scale live P2P video multicast session comprising more than 120, 000 peers on the Internet. Our analysis highlights P2P video multicast characteristics such as high bandwidth requirements, high peer churn, low peer persistence in the P2P multicast system, significant variance in the media stream quality delivered to peers, relatively large channel start times, and flash crowd effects of popular video content. Our analysis also indicates that peers are widely spread across the IP address space, spanning dozens of countries and hundreds of ISPs and Internet ASes. As part of the P2P multicast evaluation several QoS measures such as fraction of stream blocks correctly received, number of consecutive stream blocks lost, and channel startup time across peers. We correlate the observed quality with the underlying network and with peer behavior, suggesting several avenues for optimization and research in P2P video multicast systems.

DISTRIBUTED SYSTEM AND METHOD FOR THE DETECTION OF eTHREATS

Abstract: The invention relates to a distributed system for detecting eThreats that propagate in a network, which comprises: (a) graphs database storing at least one propagation graph, each graph describing the typical propagation over time of one eThreat class or a legitimate executable class within the network; (b) plurality of agents that are distributed in corresponding plurality of hosts within the network, each of said agents continuously monitoring the corresponding host and reporting to a Central Decision Maker (CDM) the identity of any new suspected executable, and the time in which said suspected executable has been first detected by said agent; (c) a CDM for: (c.1) receiving all said reports from said plurality of agents; (c.2) creating from said reports for each suspected executable a corresponding propagation graph which reflects the propagation characteristics over time of said suspected executable within the network, and (c.3) comparing each of said created graphs with said stored at least one propagation graph; (c.4) upon finding a similarity above a predefined threshold between a created graph and one of the stored graphs, concluding respectively that said executable belongs to the class as defined by said stored graph; and (c.5) conveying said conclusion to said agents, for optionally taking an appropriate action.