Dipl.-Inf.

Roscher, Karsten

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Now showing 1 - 10 of 19
  • Publication
    A Rapid Innovation Framework for Connected Mobility Applications
    (Fraunhofer ESK, 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.
  • Publication
    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.
  • Publication
    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.
  • Publication
    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.
  • 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.
  • Publication
    Feasibility of Verify-on-Demand in VANETs
    ( 2016)
    Bittl, Sebastian
    ;
    Roscher, Karsten
    Wireless ad hoc networks are an important topic in the automotive domain. Thereby, strict security requirements lead to high effort for verification of digital signatures used to secure message exchange. A popular approach to limit such effort is to apply verify-on-demand schemes. However, we show that verify-on-demand requires much more cross layer dependencies than identified before. Moreover, a massive denial of service weakness of this kind of verification mechanism is found. Thus, we recommend to prefer verify-all schemes over their verify-on-demand counterparts.
  • Publication
    Low-Delay Forwarding with Multiple Candidates for VANETs Using Multi-Criteria Decision Making
    ( 2016)
    Roscher, Karsten
    ;
    Jiru, Josef
    ;
    Knorr, Rudi
    Vehicular ad hoc networks (VANETs) are envisioned to support driver assistance and automated driving posing strict requirements on communication reliability and delay. To support these applications, we propose Low Delay Forwarding with Multiple Candidates (LDMC), a geographic routing approach combining the advantages of sender-based control and opportunistic forwarding. Candidates are ranked based on position, time since the last status update and neighborhood information using multi-criteria decision making. Priority-dependent timers reduce the contention among forwarders. Our evaluation for freeway and grid scenarios shows substantial improvement over existing protocols for real-time applications requiring 100 ms or less end-to-end delay.
  • Publication
    Efficient authorization authority certificate distribution in VANETs
    ( 2016)
    Bittl, Sebastian
    ;
    Roscher, Karsten
    Car-to-X communication systems are about to enter the mass market in upcoming years. Security in these networks depends on digital signatures managed by a multi-level certificate hierarchy. Thereby, certificate distribution is critical in regard to channel utilization and data reception delay via security caused packet loss. These issues are even more significant in case not only pseudonym certificates but also authorization authority certificates have to be exchanged between nodes in the VANET. Prior work has not studied distribution of the elements of a multi-levelcertificate chain in detail. Hence, this work provides an analysis of the currently standardized mechanisms and identifies several drawbacks of the straight forward solution proposed so far. Thereby, we find a severe denial of service attack on that solution. Moreover, the distribution problem is found to be similar to the packet forwarding problem encountered in position-based routing. Thus, we study several strategies for efficient distribution of a certificate chain in regard to channel lad, which are adapted from their counterparts in position-based routing. Thereby, we find that by combining pseudonym certificate buffering with requester based responder selection the requirement for certificate chain distribution in VANETs can be removed completely. Hence, the proposed design avoids the identified denial of service weakness and reduces the worst case size of the security envelope of VANET messages by more than a third.