Showing papers by "Hannes Hartenstein published in 2001"

A survey on position-based routing in mobile ad hoc networks

Abstract: We present an overview of ad hoc routing protocols that make forwarding decisions based on the geographical position of a packet's destination. Other than the destination's position, each node need know only its own position and the position of its one-hop neighbors in order to forward packets. Since it is not necessary to maintain explicit routes, position-based routing does scale well even if the network is highly dynamic. This is a major advantage in a mobile ad hoc network where the topology may change frequently. The main prerequisite for position-based routing is that a sender can obtain the current position of the destination. Therefore, previously proposed location services are discussed in addition to position-based packet forwarding strategies. We provide a qualitative comparison of the approaches in both areas and investigate opportunities for future research.

Position-aware ad hoc wireless networks for inter-vehicle communications: the Fleetnet project

Abstract: The Fleetnet project aims at the development of a wireless ad hoc network for inter-vehicle communications. We present the rationale behind the choice of an appropriate radio hardware and the use of a position-based routing approach and outline applications to exploit the Fleetnet platform. In addition, we discuss simulation of vehicle movements as a basis for protocol evaluation as well as aspects of Internet integration of Fleetnet. We state the basic problems together with the intended approach of tackling these challenges, thereby providing an overview of the Fleetnet project

Internet on the Road via Inter-Vehicle Communications

Abstract: Driving means constantly changing location. This, in turn, means a constant demand for information on the current location and specifically for data on the surrounding traffic. In particular, there is a demand for sensor data from other cars such as data on braking sent from a preceding car, for data on the traffic flow on a route, and for information about sites located along a route. Although need for information pertaining to the close environment of the car is obvious, so far no intervehicle communications system for data exchange between vehicles and between roadside and vehicles has been put into operation. To promote the development of such an inter-vehicle communication system, the project “FleetNet – Internet on the Road” was set up by a consortium of six companies and three universities: DaimlerChrysler AG, GMD FOKUS, NEC Europe Ltd., Robert Bosch GmbH, Siemens AG, TEMIC TELEFUNKEN microelectronic GmbH, Universities of Mannheim and Hannover, and Technische Universität Hamburg-Harburg. The project is partly funded by the German Ministry of Education and Research. FleetNet started on September 1, 2000 and will end on December 31, 2003. FleetNet aims at the development and demonstration of a wireless ad hoc network for inter-vehicle communications. Key design requirements for FleetNet are the capability to distribute locally relevant data where generated and needed and to satisfy the vehicle drivers’ and passengers’ needs for location-dependent information and services. Location awareness and position data play a crucial role not only for FleetNet applications but also for the communication protocols deployed. This paper provides an overview of the FleetNet project: we describe FleetNet applications and services as well as Fleetnet’s technical challenges together with our current design choices.

High Quality Mobile Communication

Abstract: Future communication environments have to support mobility at various levels ranging from device and personal to session and service mobility. Much effort is currently beeing spent in the areas of cellular access technology, wireless LAN technology and mobility support in IP (Mobile IP). There is a clear trend that the IP protocol is becoming the dominant networking protocol. Since standard IP networks do not provide any guarantees for the transmission quality parameters, there is a clear demand for a comprehensive QoS mechanism, which allows for adaptation in a mobile environment using heterogeneous devices with heterogeneous access networks.

On the Inverse Problem of Fractal Compression

Abstract: The inverse problem of fractal compression amounts to determining a contractive operator such that the corresponding fixed point approximates a given target function. The standard method based on the collage codingstrategy is known to represent a suboptimal method. Why does one not search for optimal fractal codes? We will prove that optimal fractal coding, when considered as a discrete optimization problem, constitutes an NP-hard problem, i.e., it cannot be solved in a practical amount of time. Nevertheless, when the fractal code parameters are allowed to vary continuously, we show that one is able to improve on collage coding by fine-tuning some of the fractal code parameters with the help of differentiate methods. The differentiability of the attractor as a function of its luminance parameters is established. We also comment on the approximating behavior of collage coding, state a lower bound for the optimal attractor error, and outline an annealing scheme for improved fractal coding.

Scalable anonymous connections in the context of MIP and AAA

Abstract: IP-packets sent over the Internet may reveal detailed information about who communicates with whom. To conceal the identities of sender and receiver, present approaches involve particular network nodes that forward the communication traffic often using cryptographic techniques to en-/decrypt the in-/outgoing data. The current anonymity approaches suite applications that do not have time constraints supporting a limited number of subscribers. These approaches are not suited for a worldwide, possibly time critical scenario with a huge number of subscribers. Diverting all communication traffic over such network nodes would cause bottlenecks and traffic delays. For concealing the relationship of sender and receiver we propose an optional, reasonable anonymity service scalable for a large number of subscribers, possible communicating under time constraints. In addition, when integrating our approach in the context of Mobile IP, authentication, authorization and accounting we neither weaken the proposed trust model nor extend the number of involved entities.

QoS Orchestration for Mobile Multimedia

Abstract: Traditional QoS methods address speci c areas such as resource reservation or end-to-end transmission paths but lack a comprehensive approach and support for mobility. In this paper we propose the MASA QoS architecture designed to provide quality of service for mobile networking scenarios by using adaptive media and mobility technologies under a central framework. This uniting of technologies allows for the evolution of synergies between previously separated areas and e ectively aligns advanced topics such as interactive media adaptation, seamless hando for mobility and advanced resource management within a "mutually advantageous" environment.