Christian Facchi
Technische Hochschule
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Publication
Featured researches published by Christian Facchi.
intelligent tutoring systems | 2015
Raphael Riebl; Hendrik-Jörn Günther; Christian Facchi; Lars C. Wolf
Development and testing of novel Advanced Driver Assistance Systems (ADASs) based on Vehicle-2-X (V2X) communication is often supported by simulations. However, simulation models for Vehicular Ad Hoc Networks (VANETs) can easily become very complex due to the diverse set of involved components such as vehicle mobility, radio propagation, network protocols and application behavior. Therefore, we present an extension to the V2X simulation framework “Vehicles in Network Simulation” (Veins) with a clear separation of concerns regarding network and application aspects. Because of distinctively modeled Facilities and Application layers, this approach enables the concurrent combination of multiple VANET application sets as well as the evaluation of their interdependencies. The proposed extension to Veins, named Artery, incorporates an implementation of the ETSI ITS-G5 protocol stack following the European specifications for V2X communication. State and perception data required for ADAS algorithms are collected and provided in an extensible manner for each vehicle. Thus, Artery represents a more holistic approach in testing novel VANET applications in a network simulation environment.
international conference on software engineering advances | 2010
Peter Trapp; Markus Meyer; Christian Facchi
Dynamic performance stubs provide a framework for the simulation of the performance behavior of software modules and functions. Hence, they can be used as an extension to software performance engineering methodologies. The methodology of dynamic performance stubs can be used for a gain oriented performance improvement. It is also possible to identify “hidden” bottlenecks and to prioritize optimization possibilities. Nowadays, the processing power of CPUs is mainly increasing by adding more cores to the architecture. To have benefits from this, new software is mostly designed for parallel processing, especially, in large software projects. As software performance optimizations can be difficult in these environments, new methodologies have to be defined. This paper extends and improves the methodology of CPU stubs and applies it to multi-core environments and parallel processing. The method is evaluated by means of a proof of concept. We were able to show that CPU stubs can be used to identify performance bottlenecks in parallel processing environments and to quantify the gain of different performance improvements. Hence, a new methodology for gain oriented optimization of CPU bound parallel processes has been validated in a case study.
Echtzeit | 2009
Peter Trapp; Christian Facchi; Markus Meyer
Dynamic Performance Stubs realisieren ein Framework zur Simulation des Performanzverhaltens von Softwaremodulen und Funktionen. Sie konnen fur eine Kosten-Nutzen-Analyse einer potentiellen Performanzoptimierung verwendet werden. Dies fuhrt zu einer ergebnisorientierten Optimierung. Ebenso ist es moglich versteckte Flaschenhalse und die wichtigsten Optimierungskandidaten zu identifizieren. Dieser Bericht beschreibt CPU Stubs im Detail und evaluiert Einsatzmoglichkeiten, um CPU gebundene Flaschenhalse zu optimieren. Durch die Optimierung wird das Einhalten von harten oder weichen Echtzeitbedingungen ermoglicht.
vehicular networking conference | 2016
Hendrik-Jörn Günther; Raphael Riebl; Lars C. Wolf; Christian Facchi
In conjunction with automated vehicles, Inter-Vehicle Communication represents the next ‘big thing’ towards the vision of cooperative driving, where road participants share information about their planned behaviour and where hazardous situations are solved or avoided jointly. Several requirements need to be fulfilled to reach this long-term goal. One requirement is a common information base, where all road participants are fully aware of each other. The idea of collective perception contributes to this common information base by sharing local sensor data with other road participants. Whereas most related work focuses on the aspects of sensor data fusion, we focus on the implications of an ETSI ITS G5 based network for collective perception. We present and analyse different message formats and dissemination variants for sharing sensor data. Their usability is validated in an extensive microscopic simulation study. In particular, implications caused by Decentralized Congestion Control as proposed by standardisation are assessed in a constrained environment with hundreds of vehicles.
ieee international conference on models and technologies for intelligent transportation systems | 2017
Christina Obermaier; Raphael Riebl; Christian Facchi
Vehicular Ad Hoc Networks (VANETs) are predestined for traffic safety applications in the domain of Inter-Vehicular-Communication (IVC) because of their low-latency connections. These applications require thorough testing to meet the high expectations regarding reliability and availability. However, IVC applications are difficult to test in the field, especially when many vehicles are involved. Thus, software is usually put “into the loop” by encapsulating it into an isolated testbed with a simulated environment. The creation of non-trivial test scenarios is a tedious process with the current tools, though. We present a novel approach for modelling IVC scenarios that supports dynamically evolving traffic conditions, e.g. due to worsening weather conditions or incidents in the course of a traffic jam. Cornerstone of this method is our dynamic scenario control based on environment conditions and effects. This paper not only presents the principles of this mechanism but also demonstrates its versatility for various standardised IVC use cases. Dynamic scenario control enables VANET simulations to be used for testing a wider range of applications even in complex scenarios.
international conference on intelligent transportation systems | 2016
Thomas Speth; Raphael Riebl; Thomas Brandmeier; Christian Facchi; Ali Hilal Al-Bayatti; Ulrich Jumar
Intelligent Transportation System (ITS) applications for integral and cooperative vehicle safety as well as some Advanced Driver Assistance Systems (ADASs) benefit from precise determination of relative positions between dynamic traffic objects. With conventional Global Navigation Satellite System (GNSS) measurements, e.g. using Global Positioning System (GPS), the required accuracy cannot be achieved. For this reason, an exchange of GNSS observations via Vehicular Ad-Hoc Network (VANET) is proposed in this paper. In particular, the European Inter-Vehicle Communication (IVC) protocol stack ITS-G5 is employed. With these exchanged GNSS observations, Differential GNSS (DGNSS) or Real-Time Kinematic (RTK) calculations provide a precise relative position vector. However, due to relative movement of traffic objects, this position vector becomes obsolete for increasing transmission delays. For this reason, a mitigating kinematic model is set up and validated experimentally. With respect to fixed RTK solutions, this kinematic model reduces the errors by an average of 61% compared to position calculations ignoring IVC latency.
Computer Communications | 2018
Hendrik-Jörn Günther; Raphael Riebl; Lars C. Wolf; Christian Facchi
Abstract In conjunction with automated vehicles, Inter-Vehicle Communication represents the next ‘big thing’ towards the vision of cooperative driving, where road participants share information about their planned behaviour and where hazardous situations are solved or avoided jointly. One prerequisite to fulfill this long-term goal is a common information base, where all road participants are fully aware of each other. The idea of collective perception contributes to this information base by sharing local sensor data with other road users. Whereas most related work focuses on the aspects of sensor data fusion, we focus on the implications of an ETSI ITS G5 based network for collective perception. We present and analyse different message formats and dissemination variants for sharing sensor data. Their usability is validated in two extensive microscopic simulation studies with different traffic densities and up to several hundred concurrent vehicles. In particular, implications caused by standardised Decentralized Congestion Control are assessed in a controlled environment.
acs/ieee international conference on computer systems and applications | 2016
Markus Zeindl; Markus Seitz; Christian Facchi
Continuous Integration (CI) is a common practice in agile software development processes. It improves the quality of the developed software and reduces the risk of integration problems. However, the effectiveness of CI depends heavily on the frequency of integration problems. For systematic improvement of the applied agile development process, the effect of large commits on the likelihood of integration problems is examined. Based on data gathered from the version control system and the CI-system of one large-scale, multi-site, agile-organized software development project in telecommunication industry, the size of commits is measured by three metrics: Count of Changed Lines, Count of Changed Files and the Count of Affected Components. As it can be found by this real life case study, there is a strong correlation between the size of a change and the likelihood of integration problems. In addition, the number of changed lines is only indirect correlated to the probability of integration problems.
web intelligence | 2015
Markus Zeindl; Christian Facchi
In ordinal classification problems, data objects are grouped into at least three different classes by an appropriate classification model, which can be arranged in a total ordering. Performance evaluation of such problems will actually be performed using imprecise evaluation metrics. This paper proposes WOC, a novel evaluation metric for ordinal classification problems and shows, that this metric acts as expected. As evaluation results confirm, the proposed metric provides more precise information about the quality of decision made by ordinal classification models.
trust security and privacy in computing and communications | 2013
Andreas Huebner; Christian Facchi; Markus Meyer; Helge Janicke
A new approach for testing Radio Frequency Identification applications is presented in this paper. Therefore, a set based semantics is introduced to describe RFID applications. The approach uses UML to model the characteristics of the system under test. The combination of three different model-types, which consist of a Domain Model, a Movement Model and Process Models, allows for the extraction of test cases and the evaluation of functional aspects of the application under test. This model-based test approach is validated on an example case study, of processes in a retail clothing shop.