Dipl.-Inf.

Roscher, Karsten

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A Rapid Innovation Framework for Connected Mobility Applications

2018 , Pöhn, Daniela , Wessel, Sascha , Fischer, Felix , Braunsdorf, Oliver , Wenninger, Franz , Seydel, Dominique , Weiß, Gereon , Roscher, Karsten , Freese-Wagner, Manuela

Connected Mobility Applications help to continuously improve traffic safety and efficiency. Today, much time and effort have to be invested to bring an idea into a safe prototype and to finally launch a reliable product.Software development tools have to adapt to these requirements. They have to support a rapid and continuous development process, that allows to test and validate the distributed application as one overall system. When developing cooperative applications, a higher design complexity has to be handled, as components are distributed over heterogeneous systems that interact with a varying timing behavior and less data confidence. Also, test and validation become more complex. Our Innovation Framework is intended to rapidly bring an idea for a connected application into a prototype so the investment risk for innovative applications is reduced. In this whitepaper we describe the approach of a Rapid InnovationTool Kit that is intended to speed up the development process for connected mobility applications. Thereby, a safe and secure prototype is available at an early development phase to gain experience within field tests that help to rapidly improve the intended application. Our software tool kit is able to find deviations from the specified behaviour and also it can instantly locate and identify erroneous functions within distributed systems. Extensive security tests can then be applied on the implemented application to ensure a secure operation. Another use case for the described testbed is to evaluate communication technologies and to find the most suitable transmission technology for a certain application. For example, short range communication with the 802.11p WLAN technology or the upcoming LTE enhancement LTE-V2X are comparable within specific scenarios. This evaluation can help to reduce the investment risk for the deployment of connected applications.

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Efficient distribution of certificate chains in VANETs

2017 , Bittl, Sebastian , Roscher, Karsten

Wireless car-to-X communication technology is about to enter the mass market within the next years. Thereby, security in created vehicular ad-hoc networks depends on digital signatures managed by a multi-level certificate hierarchy. Certificate distribution is critical in regard to channel usage and delay of data reception via security caused packet loss. These issues are even more significant in case not only pseudonym certificates, but also certificate authority certificates, have to be exchanged between nodes on demand. Prior work has not treated dissemination of higher level elements from a multi-level certificate chain in detail. Thus, this work provides a study on the recently standardized algorithms. Several drawbacks of the straight forward solution taken so far are identified, which include severe denial of service weaknesses. Solutions to the distribution problem are found to be similar to the ones of the packet forwarding problem encountered in position-based routing. Hence, we study several algorithms for efficient distribution of a certificate chain in regard to channel load, which are adapted from their counterparts in position-based routing. Thereby, a combination of pseudonym certificate buffering with requester based responder selection is found to be able to completely remove the requirement for certificate chain distribution in VANETs. The introduced design avoids the found denial of service weakness, while decreasing the worst case size of the security envelope of VANET messages by more than a third at the same time.

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Know thy neighbor - a data-driven approach to neighborhood estimation in VANETs

2017 , Roscher, Karsten , Nitsche, Thomas , Knorr, Rudi

Current advances in vehicular ad-hoc networks (VANETs) point out the importance of multi-hop message dissemination. For this type of communication, the selection of neighboring nodes with stable links is vital. In this work, we address the neighbor selection problem with a data-driven approach. To this aim, we apply machine learning techniques to a massive data-set of ETSI ITS message exchange samples, obtained from simulated traffic in the highly detailed Luxembourg SUMO Traffic (LuST) Scenario. As a result, we present classification methods that increase neighbor selection accuracy by up to 43% compared to the state of the art.

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Heterogeneous networking for cooperative applications

2016 , Roscher, Karsten

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Time-controlled neighborhood-driven policy-based network selection algorithm for message dissemination in hybrid vehicular networks

2018 , Oleinichenko, Oleg , Sevilmis, Yagmur , Roscher, Karsten , Jiru, Josef

In vehicular ad hoc networks (VANETs), successful delivery of GeoUnicast and GeoBroadcast packets depends on scenario-specific aspects like vehicle density, distribution of vehicles on the road and type of the environment (e.g., urban, rural). These aspects can significantly influence the reliability of the connection between communication parties making traditional ITS-G5 based ad hoc networks unreliable. The absence of communication partners in range, long transmission distances, non-line-of-sight (NLOS) conditions are just a few examples that could hinder ITS-G5 transmissions. In this paper, we propose a Hybrid Policy-based Network Selection Algorithm that uses LTE to strengthen and complement ITS-G5 under critical conditions in which successful transmission over the ad hoc network is highly unlikely. The main objective is to use as less LTE transmissions as possible whilst maintaining high Packet Delivery Ratio (PDR) within defined delay constraints. The results, which are derived from extensive simulation campaigns, show a clear advantage of using the hybrid scheme over solely ITS-G5 or LTE.

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On the feasibility of multi-hop communication in a realistic city scenario

2017 , Roscher, Karsten

Vehicular ad hoc networks (VANETs) are about to enter the market in the upcoming years. While direct message exchange is limited to a few hundred meters and mostly line-of sight, multi-hop forwarding can significantly extend the communication range. In this paper, the influence of network density and vehicle distribution on multi-hop communication in VANETs is investigated using a model of the city of Luxembourg. Introducing an idealistic reference routing we identify the need for high penetration rates to achieve acceptable reliability independent of the selected routing protocol. A comparison with Greedy forwarding shows its weaknesses to select proper next hop candidates when the number of equipped vehicles increases.

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Protocol modeling accuracy in VANET simulators

2017 , Bittl, Sebastian , Roscher, Karsten

Vehicular ad hoc networks are about to enter the mass market in upcoming years. High effort for real world field tests leads to high dependency of development and evaluation of such networks on simulations. We compare supported features of common simulation frameworks with current standards and study the performance impact of incomplete standard conformance. We find that a lack of support for data encoding schemes and security functionality may massively affect simulation results. Our findings apply to many well-known simulation frameworks. Proposals to overcome identified weaknesses are provided.

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Mutual influence of certificate distribution and pseudonym change strategies in vehicular ad-hoc networks

2017 , Bittl, Sebastian , Roscher, Karsten

Vehicular ad-hoc networks (VANETs) are subject to high interest from both the automotive industry as well as government bodies owing to their prospect of increasing safety of driving. Wireless data exchange within VANETs requires rigid security mechanisms to enable its usage in safety critical driver assistance systems. Requirements include not only authenticity and integrity of messages, but also privacy of drivers. We find that much research has been conducted on certificate dissemination and on privacy enhancing certificate (i.e., pseudonym) change. However, mutual influence of techniques from both domains has not been studied in prior work. Hence, we provide an analysis of such cross influence. We show that certificate change massively increases channel load under currently standardised certificate distribution mechanisms. Thus, we propose to use explicit signalling of certificate changes among nodes to limit the found overhead. The conducted evaluation shows that this approach overcomes the identified problems.

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Publication

TIMON - Hybrid Communication

2017 , Roscher, Karsten , Onieva, Enrique

Hybrid communication is an important building block for the real-time services developed in the TIMON project. The presentation gives an overview about the communication architecture and network estimation algorithms developed in the project.

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TIMON: Enhanced real time services for an optimized multimodal mobility relying on cooperative networks and open data

2016 , Roscher, Karsten

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