Andreas Luebke

Data aggregation and roadside unit placement for a vanet traffic information system

In this paper we investigate how a VANET-based traffic information system can overcome the two key problems of strictly limited bandwidth and minimal initial deployment. First, we present a domain specific aggregation scheme in order to minimize the required overall bandwidth. Then we propose a genetic algorithm which is able to identify good positions for static roadside units in order to cope with the highly partitioned nature of a VANET in an early deployment stage. A tailored toolchain allows to optimize the placement with respect to an application-centric objective function, based on travel time savings. By means of simulation we assess the performance of the resulting traffic information system and the optimization strategy.

Experimental Evaluation of UMTS and Wireless LAN for Inter-Vehicle Communication

The rapid development of mobile communication technologies in recent years allows their application for inter-vehicle communication (IVC). In this paper, we evaluate the suitability of two wireless technologies for IVC, namely Universal Mobile Telecommunication System (UMTS) and IEEE 802.11 Wireless Local Area Network (WLAN). We analyze the communication properties of these technologies and point out the requirements of applications for IVC. We present a series of practical experiments to evaluate the eligibility of each technology for applications of IVC. To obtain comparable results, we performed measurements based on IP-unicast communication, since the lower layers of the two communication technologies differ drastically. Based on the recorded data of radio coverage, latency and throughput, we draw conclusions on currently feasible and infeasible applications for each technology.

The Feasibility of a Search Engine for Metropolitan Vehicular Ad-Hoc Networks

Applications based on vehicular ad-hoc networks (VANETs) rely on information exchanged within the network. There are two different methods of exchanging information among vehicles, i.e. distributing it proactively or requesting it on-demand. Proactive distribution of information is suitable for distributing small amounts of data, comprising information of common interest for a large number of vehicles. In contrast, proactive distribution of data is not advisable if information contained therein is relevant only to a small number of vehicles or if it would require large amounts of data. A more efficient alternative in this case is on-demand information distribution, which allows information of interest to be located, requested and sent on-demand. On-demand information retrieval in sparse metropolitan-wide VANETs is challenging, as vehicles stay in the metropolitan area only for a short period of time and message exchange is impacted by communication delays. In this paper, we introduce three different concepts of a search engine for metropolitan VANETs and explain how these concepts could make it possible to allow on-demand information exchange. We compare the concepts for their applicability by evaluating their performance with respect to latency and network load.