Showing papers by "Deutsche Telekom published in 2006"

The IMS service platform: a solution for next-generation network operators to be more than bit pipes

Abstract: As third-generation (mobile) networks (3G networks) become a commercial reality, strong movements are emerging in the direction of a common infrastructure based on the Internet protocol (IP) The users' mobile devices are like another IP host connected to the Internet In such a scenario, the network operator infrastructure is degraded to bit pipes To avoid this, the 3G partnership project (3GPP) and ETSI TISPAN have designed IP multimedia subsystem (IMS), a service platform that aims to place the network operator again in the central role of service provisioning In this article we examine IMS from a mobile operator's perspective and analyse its possible adaptation to the next-generation networks

Delay of intrusion detection in wireless sensor networks

Abstract: In this paper we consider sensor networks for intrusion detection, such that node deployment, node failures and node behavior result in coverage gaps and a fraction of disconnected nodes in an otherwise dense and well-connected network We focus on the time delay for a mobile intruder to be detected by a sensor with a connected path to the sink, in contrast to existing results for the detection time by a sensor with arbitrary connectivity We model our network using a supercritical percolation model on the plane, implying the existence of a unique unbounded connected component, and we assume that the sink belongs to this component We analyze the distribution of the distance traveled by a moving target until it comes within sensing range of a node in the giant component, providing analytical bounds for linear intruder mobility and thorough simulation results for other mobility models We show that the probability that the intruder proceeds undetected exhibits non-memoryless behavior over shorter distances and an exponentially decreasing tail We also show that the time of contact with the giant component incurs considerably more delay than the time of first contact with any node, in networks with less than 10% of nodes without a path to the sink, which means that even a small percentage of node failures may have a drastic impact on the performance of intrusion detection by a wireless sensor networ

On the throughput scaling of wireless relay networks

Abstract: The throughput of wireless networks is known to scale poorly when the number of users grows. The rate at which an arbitrary pair of nodes can communicate must decrease to zero as the number of users tends to infinity, under various assumptions. One of them is the requirement that the network is fully connected: the computed rate must hold for any pair of nodes of the network. We show that this requirement can be responsible for the lack of throughput scalability. We consider a two-dimensional (2-D) network of extending area with only one active source-destination pair at any given time, and all remaining nodes acting only as possible relays. Allowing an arbitrary small fraction of the nodes to be disconnected, we show that the per-node throughput remains constant as the network size increases. As a converse bound, we show that communications occurring at a fixed nonzero rate imply a fraction of the nodes to be disconnected. Our results are of information theoretic flavor, as they hold without assumptions on the communication strategies employed by the network nodes.

REPLEX: dynamic traffic engineering based on wardrop routing policies

Abstract: One major challenge in communication networks is the problem of dynamically distributing load in the presence of bursty and hard to predict changes in traffic demands. Current traffic engineering operates on time scales of several hours which is too slow to react to phenomena like flash crowds or BGP reroutes. One possible solution is to use load sensitive routing. Yet, interacting routing decisions at short time scales can lead to oscillations, which has prevented load sensitive routing from being deployed since the early experiences in Arpanet.However, recent theoretical results have devised a game theoretical re-routing policy that provably avoids such oscillation and in addition can be shown to converge quickly. In this paper we present ReplEx, a distributed dynamic traffic engineering algorithm based on this policy. Exploiting the fact that most underlying routing protocols support multiple equal-cost routes to a destination, it dynamically changes the proportion of traffic that is routed along each path. These proportions are carefully adapted utilising information from periodic measurements and, optionally, information exchanged between the routers about the traffic condition along the path.We evaluate the algorithm via simulations employing traffic loads that mimic actual Web traffic, i. e., bursty TCP traffic, and whose characteristics are consistent with self-similarity. The simulations quickly converge and do not exhibit significant oscillations on both artificial as well as real topologies, as can be expected from the theoretical results.

Corporate Foundations: Their Role for Corporate Social Responsibility

Abstract: According to their statutes and published objectives, many foundations focus on the solution of social problems and on responding to unmet social needs. They aim at social value creation and serve as an ‘antenna’ or ‘sensor’ for societal needs and expectations. If the work of the foundation is coordinated with that of the founding corporation and knowledge is flowing between these organizational entities, corporations can profit from the foundation's activities and insights. However, since corporate foundations by their legal nature and very statutes are independent entities that are to exclusively pursue public-benefit purposes, this relationship is not free of potential conflicts of interest. Through expert interviews with representatives of five major corporate foundations in Germany and their founding corporations, the practices of this cooperation were explored and implications for its improvement were discussed.

Investigation of Brillouin scattering in optical fibers for the generation of Millimeter waves

Abstract: Stimulated Brillouin scattering (BS) in optical fibers is investigated for the generation of millimeter waves (mm-waves) for radio over fiber systems. Predictions of a numerical simulation are compared to experimental results, and both are in good agreement with each other. With the numerical simulation, the optimum parameter for the technique is calculated. It will be shown that the optimum length of the fiber for BS depends on the signal rather than on the pump power. This gives us the opportunity to adjust the parameters for any given fiber length. The advantages and limits of the proposed method for mm-wave generation are discussed.

Engineering benchmarks for planning: the domains used in the deterministic part of IPC-4

Abstract: In a field of research about general reasoning mechanisms, it is essential to have appropriate benchmarks. Ideally, the benchmarks should reflect possible applications of the developed technology. In AI Planning, researchers more and more tend to draw their testing examples from the benchmark collections used in the International Planning Competition (IPC). In the organization of (the deterministic part of) the fourth IPC, IPC-4, the authors therefore invested significant effort to create a useful set of benchmarks. They come from five different (potential) real-world applications of planning: airport ground traffic control, oil derivative transportation in pipeline networks, model-checking safety properties, power supply restoration, and UMTS call setup. Adapting and preparing such an application for use as a benchmark in the IPC involves, at the time, inevitable (often drastic) simplifications, as well as careful choice between, and engineering of, domain encodings. For the first time in the IPC, we used compilations to formulate complex domain features in simple languages such as STRIPS, rather than just dropping the more interesting problem constraints in the simpler language subsets. The article explains and discusses the five application domains and their adaptation to form the PDDL test suites used in IPC-4. We summarize known theoretical results on structural properties of the domains, regarding their computational complexity and provable properties of their topology under the h+ function (an idealized version of the relaxed plan heuristic). We present new (empirical) results illuminating properties such as the quality of the most wide-spread heuristic functions (planning graph, serial planning graph, and relaxed plan), the growth of propositional representations over instance size, and the number of actions available to achieve each fact; we discuss these data in conjunction with the best results achieved by the different kinds of planners participating in IPC-4.

A study of the short message service of a nationwide cellular network

Abstract: In recent years, cellular networks have experienced an astronomical increase in the use of Short Message Service (SMS), making it a popular communication means for inter-personal as well as content provider-to-person usage. Yet little is known about the traffic and message user behavior in real SMS systems. In this paper, we present a measurement study of SMS based on traces collected from a nationwide cellular carrier during a three-week period. We characterize message traffic at both the message level and the conversation thread level. We also examine the "store-and-forward" mechanism of SMS and present initial measurements on how messages are actually delivered.

Making university-industry collaboration work - a case study on the Deutsche Telekom Laboratories contrasted with findings in literature

Abstract: The growing competition in consumer as well as business customer markets is forcing industry to explore new ways to foster product and service innovations. To increase the clock speed of incremental innovations and raise the number of radical innovations, university-industry collaborations (UIC) are a powerful means discussed by practitioners as well as by scholars. This paper discusses the approach of the Deutsche Telekom Group (DTAG) of building a UIC by creating a separate organization. This organization consists of R&D personnel both from industry and academia and proves to be effective in channelling innovation potential. Being an organization with its own identity and situated on university premises, the Deutsche Telekom Laboratories (DT Laboratories) offer different ways to overcome the cultural, institutional and operational barriers associated with UIC. The case study validates and challenges findings on UIC in literature. The paper closes with practical advices for the establishment and management of UIC and suggestions for further research in this field.

The Technology Radar - an Instrument of Technology Intelligence and Innovation Strategy

Abstract: This paper analyzes the establishment of a technology intelligence tool of the Deutsche Telekom Laboratories - the Technology Radar. Goals and method are contrasted to approaches discussed in literature. After the presentation of exemplary findings of the Technology Radar, the role of the Technology Radar within the innovation and technology management of the Deutsche Telekom is being discussed. The paper closes with lessons learned, key success factors are being highlighted and recommendations for the introduction of technology intelligence systems are given.

An enactive approach to the design of new tangible musical instruments

Abstract: In this paper, we propose a theoretical framework for the design of tangible interfaces for musical expression. The main insight for the proposed approach is the importance and utility of familiar sensorimotor experiences for the creation of engaging and playable new musical instruments. In particular, we suggest exploiting the commonalities between different natural interactions by varying the auditory response or tactile details of the instrument within certain limits. Using this principle, devices for classes of sounds such as coarse grain collision interactions or friction interactions can be designed. The designs we propose retain the familiar tactile aspect of the interaction so that the performer can take advantage of tacit knowledge gained through experiences with such phenomena in the real world.

Believability testing and bayesian imitation in interactive computer games

Abstract: In imitation learning, agents are trained to carry out certain actions by examining a demonstration of the task at hand Though common in robotics, little work has been done in translating these concepts to computer games Given that present-day games generally use antiquated AI techniques which can often lead to stilted, mechanical and conspicuously artificial behaviour, it seems likely that approaches based on the imitation of human players may produce agents which convey a more humanlike impression than their traditional counterparts At the same time, there exists no formal method of quantifying what constitutes a ‘humanlike' impression; an equivalent of the Turing test is needed, with the requirement that an agent's appearance and behaviour be capable of deceiving an observer into misidentifying it as human The aims of this paper are thus threefold; we describe an approach to the imitation of strategic behaviour and motion, propose a formal method of quantifying the degree to which different agents are perceived as ‘humanlike', and present the results of a series of experiments using these two systems.

Web search clickstreams

Abstract: Search engines are a vital part of the Web and thus the Internet infrastructure. Therefore understanding the behavior of users searching the Web gives insights into trends, and enables enhancements of future search capabilities. Possible data sources for studying Web search behavior are either server-side logs or client-side logs. Unfortunately, current server-side logs are hard to obtain as they are considered proprietary by the search engine operators. Therefore we in this paper present a methodology for extracting client-side logs from the traffic exchanged between a large user group and the Internet. The added benefit of our methodology is that we do not only extract the search terms, the query sequences, and search results of each individual user but also the full clickstream, i.e., the result pages users view and the subsequently visited hyperlinked pages. We propose a finite-state Markov model that captures the user web searching and browsing behavior and allows us to deduce users' prevalent search patterns. To our knowledge, this is the first such detailed client-side analysis of clickstreams.

Potential ultra wide slow-light bandwidth enhancement.

Abstract: We describe a method which has the potential to enhance the bandwidth of Brillouin based slow-light delay lines drastically It is based on the overcompensation of the anti Stokes loss spectrum by additional pump sources With this method it might be possible to overcome the bandwidth limit of Brillouin scattering which for one pump wave is given by two times the natural Brillouin shift in the incorporated waveguide We will show experimentally that pulses can be delayed in the overcompensated loss spectrum

Detecting Anger in Automated Voice Portal Dialogs

Abstract: Anger detection is a topic that is gaining more and more attention with voice portal carriers, as it can be useful for quality measurement and emotion-aware dialog strategies. In the context of a prototype voice portal we describe methods to search for training data, report on the performance of the prosodic classifier under real world conditions and explore the use of dialog information for anger prediction. The results show that, although significantly worse than under laboratory conditions, anger detection still works well above chance level and can be used to enhance real world voice-portal usability. Index Terms: Emotion Recognition, Voice Portal, Speech Classification, Dialogue System.

A Cost Model for the WDM Layer

Abstract: In this paper a detailed capital expenditure cost model is presented taking various network elements and node architectures at the WDM layer into account. It was developed within the European NOBEL project [1] and aligned by major European network suppliers and operators. The current cost structure of WDM transport equipment is shown in a normalised format. Typical model applications are also discussed by presenting examples. This model can serve as a reference for future techno-economic research into optical transport networks in general.

Method for verifying access authorization for voice telephony in a fixed network line or mobile telephone line as well as a communications network

Abstract: A method for verifying access authorization for voice telephony in a fixed network line or mobile telephone line, as well as a communications network having such access authorization verification are described. The access authorization is verified by analysis of a voice signal which was entered by the subscriber placing the call, before or during a call in progress. In one variant, the voice signal is entered as a password before the connection is established; in another variant, voice signals are analyzed for voice recognition and subscriber identification, the same voice signals also being transmitted to the person being called, making concealed access verification possible which does not hamper the normal flow of conversation.

Common technical specification of the G-PON system among major worldwide access carriers

Abstract: Gigabit-capable passive optical networks (G-PONs) have been successfully standardized at ITU-T following the work done by the Full-Service Access Network (FSAN) group. G-PON is a powerful and flexible optical access system with various options to accommodate many services and interface types. In order to provide guidance to vendors on the key options required by operators at this time and hence speed up early volumes for large field trials and deployments, many of the major worldwide access carriers (AT&T, BT, DT, FT, KT, NTT, and TI) have developed a common technical specification (CTS) for G-PON systems. This article describes the G-PON standard and underlines the scope and results of the CTS

Experimental evaluation and characterization of the magnets wireless backbone

Abstract: High-speed wireless backbones have the potential to replace or complement wired connections. This paper provides a comprehensive network and transport layer performance evaluation of the Magnets WiFi backbone. The backbone, deployed in a metropolitan area of Berlin, consists of six 108 Mbps capable links using directional antennas and spans over 2.3 km. Built with off-the-shelf hardware, it features mixed 802.11a/g technology, link distances between 330 m and 930 m and support for two enhanced MAC/PHY layer modes at the access points (AP) to improve their performance. These unique characteristics provide a challenging environment to investigate the impact of a wide range of parameters. In particular, using CBR and VBR traffic profiles, we assess the influence of distance, 802.11 technology and AP modes on throughput, delay, packet loss and jitter between pairs of adjacent nodes. For example, our measurements show that the average UDP throughput of the 802.11g links varies between 15.9 and 18.7 Mbps, whereas the 802.11a link achieves 27.8 Mbps. Finally, the average UDP throughput can even be increased to 55.2 Mbps by concomitantly enabling the two enhanced AP modes.

Coded 64-CAP ADSL in an impulse-noise environment-modeling of impulse noise and first simulation results

Abstract: This paper presents the performance of various coding schemes for the asymmetrical digital subscriber line (ADSL) in an impulse-noise environment. Impulse noise is considered to be one of the most damaging impairments in the ADSL, in which compressed video signals are delivered to residential customers. The impulse noise used in this study was measured and collected in German telephone networks. Based on this measurement and the corresponding statistical modeling, a simulation model for impulse noise is proposed and its properties are outlined. The coding schemes considered here utilize burst-error correcting Reed-Solomon codes and/or random error correcting trellis codes as well as symbol interleaving between the two codes. It has been found through computer simulations that a proper concatenation of the two codes could increase the immunity against impulse noise compared to an uncoded scheme. Specifically, a concatenated code, using a 2-dimensional 8-state trellis code and a 4-error-correcting Reed-Solomon code with an interleaving depth of 18 symbols, was able to eliminate all the errors caused by the impulse noise used in the study. It has also been found that the trellis codes are not very effective against impulse noise, unless they are used in conjunction with Reed-Solomon codes and a proper symbol interleaving. Performance results of other coding configurations using Reed-Solomon codes with different error-correcting capabilities are also presented. In addition, we also show the performance results when simple array codes are used instead of the Reed-Solomon codes

Joint routing and rate allocation for multiple video streams in ad-hoc wireless networks *

Abstract: The support for multiple video streams in an ad-hoc wireless network requires appropriate routing and rate allocation measures ascertaining the set of links for transmitting each stream and the encoding rate of the video to be delivered over the chosen links. The routing and rate allocation procedures impact the sustained quality of each video stream measured as the mean squared error (MSE) distortion at the receiver, and the overall network congestion in terms of queuing delay per link. We study the trade-off between these two competing objectives in a convex optimization formulation, and discuss both centralized and dis- tributed solutions for joint routing and rate allocation for multiple streams. For each stream, the optimal allocated rate strikes a balance between the selfish motive of minimizing video distortion and the global good of minimizing network congestions, while the routes are chosen over the least-congested links in the network. In addition to detailed analysis, network simulation results using ns-2 are presented for studying the optimal choice of parameters and to confirm the effectiveness of the proposed measures.

CaMus: live music performance using camera phones and visual grid tracking

Abstract: We demonstrate that mobile phones can be used as an actively oriented handheld musical performance device. To achieve this we use a visual tracking system of a camera phone. Motion in the plane, relative to movable targets, rotation and distance to the plane can be used to drive MIDI enabled sound generation software or hardware. Mobile camera phones are widely available technology and we hope to find ways to make them into viable and widely used performance devices.

Distortion reduction in cascaded slow light delays

Abstract: A technique for the distortion reduction of delayed pulses in single and cascaded slow light delay lines is demonstrated. The method is based on the overlap of different independent Brillouin gains. With three Brillouin lines a distortion reduction of around 30% in a two-segment delay line was achieved.

Evolution of Terrestrial Optical System and Core Network Architecture

Abstract: Optical systems and technologies have been radically changing the telecommunication networks for past 15 years; today wavelength division multiplexing (WDM) technology, optical amplifiers, and simple optical switching elements like optical add-drop multiplexers (OADMs) are used in the backbone networks of all operators worldwide. Optical systems nowadays provide the basis for cost-effective transmission of large amounts of bandwidth over the Internet, and will enable its future growth and the spreading of new applications and services. This paper summarizes the main trends in optical networking and investigates potential future application areas. Optical system technology has become so pervasive in network design that it needs to be considered in the context of provisioning new applications and services. Therefore, the analysis is not limited to the aspects of physical transmission, but also takes into account recent developments in integrated network design as well as network control and management. The following sections describe the key functionalities of future optical network architectures, and the key findings of the theoretical analysis are supported by the results of a field trial of advanced transmission technology

Mining source code elements for comprehending object-oriented systems and evaluating their maintainability

Abstract: Data mining and its capacity to deal with large volumes of data and to uncover hidden patterns has been proposed as a means to support industrial scale software maintenance and comprehension. This paper presents a methodology for knowledge acquisition from source code in order to comprehend an object-oriented system and evaluate its maintainability. We employ clustering in order to support semi-automated software maintenance and comprehension.A model and an associated process are provided, in order to extract elements from source code; K-Means clustering is then applied on these data, in order to produce system overviews and deductions. The methodology is evaluated on JBoss, a very large Open Source Application Server; results are discussed and conclusions are presented together with directions for future work.

Method and communication system for optimizing the throughput of a TCP flow in a wireless network

Abstract: A method and a system is provided for optimizing the throughput of a TCP flow from a TCP source to a TCP destination in a wireless network with the path of the flow encompassing a wireless link between a wireless transmitter and a wireless receiver. The throughput is optimized by using link-layer mechanisms at the wireless transmitter which are adaptive to the instantaneous TCP dynamics of the TCP flow. In particular, a cross-layer approach is disclosed which serves to tunnel information of TCP congestion control dynamics directly from the TCP based transport layer to the data link-layer which selects in response to these information modulation and/or coding schemas to transmit TCP segments via data link-layer blocks with improved TCP throughput.

Method for disseminating drm content

Abstract: Method for disseminating digital content that is secured by Digital Rights Management (DRM), the digital content being encrypted and playback of the digital content being linked to a license that is provided with a digital key including associated attributes that regulate at least one of a type, a scope and a duration of a permissible utilization of the digital content, including: generating a DRM ticket including an unambiguous destination address on a DRM server contactable via a computer network, the DRM ticket configured to enable a user in possession of the DRM ticket to download, at the destination address, a first license onto a device configured to play digital content; making the DRM ticket available to a buyer of the first license; and generating the first license based on rights coupled to the DRM ticket at a moment of a download of the first license onto the DRM server, the rights being stipulated by a content provider when the DRM ticket is generated.

Reordering of Packets due to Multipath Forwarding - An Analysis

Abstract: Increased parallelism in routers necessary to handle high link speeds and large routing tables, wireless ad hoc routing, QoS provisioning, and overlay routing, are some of the factors that lead to an increase in reordering on the Internet. Packet reordering due to packet forwarding over multiple paths is investigated. An analytical model is derived for load splitting scenarios and verified using emulated topologies. The resulting reordering is profiled using reorder density, and analyzed with respect to path delays, path probabilities and number of paths. The variation of packet displacement with delay variation and forwarding probabilities is quantified. The special case corresponding to two paths is evaluated in detail. For any load splitting, the increase in the difference in the delay between paths leads to increased reordering, making the paths with closer delay values more preferable. The model can also be applied to a single-path case where reordering is caused by wide delay variation among packets, by deriving an equivalent set of probabilities corresponding to path splitting scenario.

Fast data access over asymmetric channels using fair and secure bandwidth sharing

Abstract: We propose a peer-to-peer architecture designed to overcome asymmetries in upload/download speeds that are typical in end-user dialup, broadband and cellular wireless Internet connections. Our approach allows users at remote locations to access information stored on their home computers at rates often exceeding their home connection’s upload capacity. The key to this approach is to share file data when communications are idle using random linear coding, so that, when needed, an end-user can download a file from several sources at a higher data rate than his home computer’s upload capacity. We prove that our proposed system is asymptotically fair, in that (even malicious) users are proportionally assigned idle bandwidth depending on how much bandwidth they contribute, and that there is a natural incentive to join and cooperate fairly in the system. In addition, our approach provides cryptographic security and geographic data robustness to the participating peers.