10402 Abstracts Collection and Executive Summary -- Inter-Vehicular Communication

From October 3 to October 6, 2010, the Dagstuhl Seminar 10402 ``Inter-Vehicular Communication\u27\u27 was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar are put together in this paper. The first section describes the seminar topics and goals in general

Selbstorganisierende Kommunikation in automobilen Ad-hoc-Netzen

Die Arbeit untersucht Techniken für Komfortapplikationen in automobilen Ad-hoc-Netzen, die eine Verbreitung von (Verkehrs-)informationen über große Entfernungen ermöglichen. Ausgestattet mit einem selbstorganisierenden Funksystem bilden die Fahrzeuge in ihrer lokalen Umgebung spontan ein drahtloses Netzwerk. Den Schwerpunkt der Untersuchungen bilden zwei Fragestellungen, die für den Einsatz eines solchen Netzwerkes von zentraler Bedeutung sind: die Kommunikation bei geringen Ausstattungsgraden sowie die Vermeidung von Überlastsituationen bei stärkerer Verbreitung des Systems.The thesis investigates techniques for comfort applications in Vehicular Ad Hoc Networks (VANETs) that disseminate (traffic) information in a large area. Equipped with a self-organizing wireless communication system, the vehicles form a local ad hoc network for information exchange. The thesis focuses on two key challenges for the application of VANET technologies: 1) communication in the phase of market introduction where only a low number of vehicles is equipped with the communication system and 2) avoidance of overload when a larger market penetration is achieved

A Resource-Based Approach To Mac Layer Independent Hierarchical Link-Sharing In Wireless Local Area Networks

The growing deployment of wireless local area networks (WLANs) in corporate environments and the increasing number of wireless Internet service providers create a need for controlled sharing of wireless bandwidth. In this paper, a method for using long-term channel-state information in order to control the sharing of wireless bandwidth is studied. The algorithm enables an operator of a WLAN to equalize the revenue/cost for each customer in the network and to control the link-sharing based on a combination of user-centric and operator-centric factors. As an example, we adapt one of the well-know wireline schedulers for hierarchical linksharing, the Hierarchical Fair Service Curve Algorithm (H-FSC), for the wireless environment and demonstrate through simulations that the modified algorithm is able to improve the controlled sharing of the wireless link without requiring modifications to the MAC layer. In addition, we present first measurements of a prototype implementation

Congestion Control in Vehicular Ad Hoc Networks

Vehicular Ad hoc Networks (VANET) play an important role in future car-to-car communication systems and related applications like Self-Organizing Traffic Information Systems (SOTIS), which are based on broadcast/geocast transmission schemes. Congestion control for VANETs has not been studied thoroughly so far -- but this feature will be extremely necessary for VANET applications and network performance. Due to the high mobility and the resulting highly dynamic network topology, congestion control will need to be performed in a decentralized and self-organized way, locally in each VANET node

Packet Scheduling for Link-Sharing and Quality of Service Support in Wireless Local Area Networks

The growing deployment of wireless local area networks (WLANs) in corporate environments, the increasing number of wireless Internet service providers and demand for quality of service support create a need for controlled sharing of wireless bandwidth. In this technical report a method for using long-term channel-state information in order to control the sharing of wireless bandwidth is studied. The algorithm enables an operator of a WLAN to equalize the revenue/cost for each customer in the network and to control the link-sharing based on a combination of user-centric and operator-centric factors. As an example, we adapt one of the well-know wireline schedulers for hierarchical link-sharing, the Hierarchical Fair Service Curve Algorithm (H-FSC), for the wireless environment and demonstrate through simulations that the modified algorithm is able to improve the controlled sharing of the wireless link without requiring modifications to the MAC layer. In addition, we present the design and implementation for a Linux based prototype. Measurements in a wireless testbed confirm that the scheduling scheme can perform resource-based link-sharing on currently available hardware conforming to the IEEE 802.11 standard

On Context-Aware Communication Mode Selection in Hybrid Vehicular Networks

Future vehicles will most-likely have multiple communication technologies and modes available. After classifying V2X applications in five distinct classes, a context-aware selection of the communication mode is advocated. A suitable architecture is outlined. First simulation results for the example of a DENM-based application indicate that a context-aware selection outperforms a static assignment

Aspects of Decentralized Time Synchronization in Vehicular Ad hoc Networks

Active safety and advanced driver assistance systems based on vehicular ad hoc networks can significantly increase passenger safety and comfort. For communication systems based on time-slotted multiple access schemes, time synchronization among the rapidly moving vehicles is required. In this paper, a new scheme for decentralized time synchronization is proposed. It will be derived analytically, that using existing schemes, a common systematic drift of the node timing can be observed, caused by the propagation delay. If the average propagation delay to nodes within the respective synchronization range differs from node to node, a remaining timing offset will be observed between stations, in a steady state. Depending on the network topology, this timing offset can be large enough to violate the constraints for a synchronous operation

Stimuli Generation for Quality-of-Experience Evaluation of Mobile Applications

The assessment of Quality-of-Experience (QoE) corresponding to a given set of Quality-of-Service (QoS) parameters is of high importance for any mobile network operator. Methods for subjective QoE assessment such as MUlti Stimulus test with Hidden Reference and Anchors (MUSHRA) or Subjective Assessment Methodology for Video Quality (SAMVIQ) are based on collecting user feedback for one or several stimuli, i.e. differently processed versions of a source. Generating these stimuli corresponding to a given set of QoS parameters for a QoE assessment of a mobile application is a time-consuming, non-trivial task. Therefore, in this paper we propose a novel publicly available open-source framework for stimuli generation for QoE assessment of mobile applications. It is based on the combination of network emulation and automatic user-interface control of a real mobile device, whose behavior is recorded and post-processed to generate suitable stimuli. The article presents the basic concept of the framework, describes its open-source implementation, and concludes with an initial evaluation of the framework based on typical types of mobile applications

Requirements and Objectives for Secure Traffic Information Systems

Early approaches for Traffic Information Systems (TISs) primarily focused on centralized systems using unidirectional downlink communication and employing wireless broadcast or similar techniques. In general, these centralized TISs were operated by public radio stations, thus there were almost no security issues related to this approach. The situation changes when new Inter Vehicle Communication (IVC) techniques are investigated. The advantages of improved timeliness and accuracy of available traffic information come with a number of security concerns. This paper reviews the requirements and objectives for secure TISs. We outline possible solutions to face the security concerns and clearly depict open issues. In conclusion, we advocate more secure TISs that benefit from recent IVC technologies in a more secure and privacy protecting way