Jörg Eberspächer

Bio: Jörg Eberspächer is an academic researcher from Technische Universität München. The author has contributed to research in topics: The Internet & Active networking. The author has an hindex of 7, co-authored 26 publications receiving 521 citations.

GSM phase 2+ general packet radio service GPRS: Architecture, protocols, and air interface

Abstract: The general packet radio service (GPRS) is a new bearer service for GSM that greatly improves and simplifies wireless access to packet data networks, e.g., to the Internet. It applies a packet radio principle to transfer user data packets in an efficient way between mobile stations and external packet data networks. This tutorial gives an introduction to GPRS. The article discusses the system architecture and its basic functionality. It explains the offered services, the session and mobility management, the routing, the GPRS air interface including channel coding, and the GPRS protocol architecture. Finally, an interworking example between GPRS and IP networks is shown.

HiiMap: Hierarchical internet mapping architecture

Abstract: Many researchers working on concepts for the next generation internet agree that the split of identifier and locator seems to be a very promising approach. Although this solution addresses the most critical issues in today's internet, new challenges arise through the mapping between locator and identifier. Our proposal takes a look at novel DHT-based mapping concepts and points out the trust problem which is introduced by many of these concepts. A new architectural concept based on administrative regions to handle mapping requests is proposed while still considering trust, security and mobility.

Availability Evaluation of Hybrid Wireless Optical Broadband Access Networks

Abstract: The hybrid Wireless-Optical Broadband Access Network (WOBAN) architecture providess a new and promising architecture for access networks by combining the beneficial properties of wireless and optical technologies. Thus it can achieve low deployment costs (as no cable infrastructure is necessary for the last mile) and provide a mobile yet economically viable end-user access. However, the integration of these technologies (optical and wireless) also has its challenges: While optical links have high availabilities (especially with modern protection techniques), the performance of wireless links depends on a variety of external parameters, which in many cases can be only described statistically. In this work, we evaluate the availability performance of a WOBAN in different demand scenarios and study the influence of various routing strategies (shortest paths with different link metrics, specialised routing algorithms for a WOBAN and multi-path routing). Our results show that we can significantly improve availability for end-users by using Shortest Path Routing with link unavailability as the link cost metric. Using multi-path routing, further gains can be achieved

A Novel DHT-Based Network Architecture for the Next Generation Internet

Abstract: The Internet architecture of today is the result of a constant evolution during the past 25 years. However, this layering of add-ons, bug fixes and extensions has grown into a tremendously complex and, therefore, increasingly static platform. On the contrary, a multitude of new challenges related to issues never conceived in the original design, such as security and mobility has become more and more important. Hence, we propose a clean-slate approach based on a two-tier locator identifier split. Combined with Distributed Hash-Tables (DHT), we developed a scalable long-term alternative to the current Internet architecture.

Fundamentals of Queueing Theory

Abstract: Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.

Handoff in hybrid mobile data networks

Abstract: With the emergence of a variety of mobile data services with variable coverage, bandwidth, and handoff strategies, and the need for mobile terminals to roam among these networks, handoff in hybrid data networks has attracted tremendous attention. This article presents an overview of issues related to handoff with particular emphasis on hybrid mobile data networks. Issues are logically divided into architectural and handoff decision time algorithms. The handoff architectures in high-speed local coverage IEEE 802.11 wireless LANs, and low-speed wide area coverage CDPD and GPRS mobile data networks are described and compared. A survey of traditional algorithms and an example of an advanced algorithm using neural networks for PTO decision time in homogeneous networks are presented. The HO architectural issues related to hybrid networks are discussed through an example of a hybrid network that employs GPRS and IEEE 802.11. Five architectures for the example hybrid network, based on emulation of GPRS entities within the WLAN, mobile IP, a virtual access point, and a mobility gateway (proxy), are described and compared. The mobility gateway and mobile IP approaches are selected for more detailed discussion. The differences in applying a complex algorithm for HO decision time in a homogeneous and a hybrid network are shown through an example.

The $\alpha$ - $\mu$ Distribution: A Physical Fading Model for the Stacy Distribution

Abstract: This paper introduces a fading model, which explores the nonlinearity of the propagation medium. It derives the corresponding fading distribution-the alpha-mu distribution-which is in fact a rewritten form of the Stacy (generalized Gamma) distribution. This distribution includes several others such as Gamma (and its discrete versions Erlang and central Chi-squared), Nakagami-m (and its discrete version Chi), exponential, Weibull, one-sided Gaussian, and Rayleigh. Based on the fading model proposed here, higher order statistics are obtained in closed-form formulas. More specifically, level-crossing rate, average fade duration, and joint statistics (joint probability density function, general joint moments, and general correlation coefficient) of correlated alpha-mu variates are obtained, and they are directly related to the physical fading parameters

Mobile Wireless Communications

Abstract: Wireless communication has become a ubiquitous part of modern life, from global cellular telephone systems to local and even personal-area networks. This 2004 book provides a tutorial introduction to digital mobile wireless networks, illustrating theoretical underpinnings with a wide range of real-world examples. The book begins with a review of propagation phenomena, and goes on to examine channel allocation, modulation techniques, multiple access schemes, and coding techniques. GSM and IS-95 systems are reviewed and 2.5G and 3G packet-switched systems are discussed in detail. Performance analysis and accessing and scheduling techniques are covered, and the book closes with a chapter on wireless LANs and personal-area networks. Many worked examples and homework exercises are provided and a solutions manual is available for instructors. The book is an ideal text for electrical engineering and computer science students taking courses in wireless communications. It will also be an invaluable reference for practising engineers.

Stability of end-to-end algorithms for joint routing and rate control

Abstract: Dynamic multi-path routing has the potential to improve the reliability and performance of a communication network, but carries a risk. Routing needs to respond quickly to achieve the potential benefits, but not so quickly that the network is destabilized. This paper studies how rapidly routing can respond, without compromising stability.We present a sufficient condition for the local stability of end-to-end algorithms for joint routing and rate control. The network model considered allows an arbitrary interconnection of sources and resources, and heterogeneous propagation delays. The sufficient condition we present is decentralized: the responsiveness of each route is restricted by the round-trip time of that route alone, and not by the round-trip times of other routes. Our results suggest that stable, scalable load-sharing across paths, based on end-to-end measurements, can be achieved on the same rapid time-scale as rate control, namely the time-scale of round-trip times.