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Über dieses Buch

This book constitutes the joint refereed proceedings of the Third International Workshop on Communication Technologies for Vehicles, Nets4Cars 2011and the First International Workshop on Communication Technologies for Vehicles in the Railway Transportation, Nets4Trains 2011, held in Oberpfaffenhofen, Germany, in March 2011. The 7 full papers of the rail track and 12 full papers of the road track presented together with a keynote were carefully reviewed and selected from 13 and 21 submissions respectively. They provide an overview over the latest technologies and research in the field of intra- and inter-vehicle communication and present original research results in areas relating to communication protocols and standards, mobility and traffic models, experimental and field operational testing, and performance analysis.




Requirements for Wireless Technology on Rolling Stock

This paper gives an overview of railway specific requirements on wireless technologies and discusses the influence of different product life cycles in railway industry and communication technology. The main challenges are the heterogeneous communication infrastructure at the wayside and the specific requirements on vehicle speed and geographical characteristics. The current state of European research and international standardization activities for on-board communication equipment is summarized and the need for a standardized application interface on the railway vehicle and at the wayside is explained. Finally, challenges for future research and development in railway applications are identified.
Uwe Kucharzyk

Rail Track

An Experimental Study of Multi-radio Platform Coexistence in the 5 GHz Band for Railway Applications

This paper studies the practical challenges that arise due to the coexistence of two wireless technologies, both operating in the license-exempt 5 GHz band. In particular, WiFi and WiMAX equipment have been used in the experiments. The mutual interference caused by the two technologies operating in different but narrowly separated frequency channels has a negative impact on the performance of both systems. Further challenges are introduced when the two systems are in close physical proximity of each other or, in a more extreme scenario, share the same antenna as could be required in railway applications. This paper investigates these issues through a series of experimental tests based on a multi-radio platform testbed. The conclusions drawn from this study will be used as a base for the implementation of a multi-radio platform to provide communications between train and land in both directions in the context of the Spanish high-speed railway system.
Jorge Higuera, Elli Kartsakli, Carlos Collado, José M. González-Arbesú, Luis Alonso, José Luis Valenzuela, Andres Laya, Enrique Flores, Isabel Navarro, Raquel Martínez, Jesús González, José Hierro, Adrian Vlad

Train Tracking and Shadowing Estimation Based on Received Signal Strength

In this work, we present an on-board solution for train position tracking that can be used in cases of GPS failures and that does not suffer from the error accumulation problem of Dead Reckoning (DR). It is based on Received Signal Strength (RSS) measured in radio communication systems by several mobile stations having antennas placed on top of different carriages of the train. As the RSS is affected by the slow fading or shadowing, both the position and the shadowing are jointly tracked. We estimate the shadowing atlas consisting of the shadowing maps along the railway of the different base stations. The proposed solution applies Bayesian filtering for efficiently processing the observations.
Hadi Noureddine, Damien Castelain, Ramesh Pyndiah

Delivering Broadband Internet Access for High Speed Trains Passengers Using an Innovative Network Mobility Solution

This paper presents a description of the connectivity solution designed in Orange Labs R&D to enable the delivery of broadband internet access services on board high speed trains. Since a couple of years, several technical studies have been launched on the network mobility management across different access networks for the implementation of broadband on board-ground communications solutions. These studies are supported by an internal project, Mobile Router in Multiple Access, launched by Orange Labs in 2005 in order to develop technical solutions for the delivery of broadband access services and which led to the build of a connectivity solution to answer requirements for the equipment of high speed trains. Orange deployed an infrastructure supporting these internet connectivity services. This paper explains in detail the technical features that are implemented in the mobility solution to provide a broadband internet access and guarantee an efficient and seamless mobility across heterogeneous access networks. A further evolution of the mobile router towards ITS architecture is approached in the paper.
Bernadette Villeforceix

Measurement and Analysis of the Direct Train to Train Propagation Channel in the 70 cm UHF-Band

In this paper we present first analyses and results of a comprehensive measurement campaign investigating the propagation channel in case of direct (base station free) communication between railway vehicles. The measurements cover urban, suburban and rural environments along a multifaceted regional railway network in the south of Bavaria. Beside different operational conditions like front, rear, and flank approaches of trains, we investigated several topological scenarios on both, single and double track sections along the line. We will also discuss the observed characteristic changes in narrow band signal attenuation and Doppler spectra for passages through forests, hilly areas, stations and a tunnel.
Andreas Lehner, Cristina Rico García, Thomas Strang, Oliver Heirich

WiMax’ble Pervasive Cloud – Empowering Next Generation Intelligent Railway Infrastructure

One of the major expectation from any next generation Railway Intelligent Infrastructure will be to reduce track side infrastructure to an extent possible by empowering on-board infrastructure as this enhances operational efficiency while reducing cost. If a broadband technology is made available in a dynamic train environment that could address critical signaling and control system requirements as well as empowers the train passengers - with on-board broadband it will boost business avenues. Pervasive Cloud combines the Power of the Cloud through Pervasive Mobile access . WiMax empowered pervasive access could address critical signalling/control systems requirements while Pervasive cloud itself addressing demands of passengers including but not limited to voice and data services at high speeds, there by addressing the goals of next generation intelligent infrastructure for railways. This paper while giving a futuristic view of related work in our Labs, intends to argue that WiMax’ble Pervasive Cloud (WiMax empowered Pervasive Cloud) could probably be a right candidate to address the expectations and aspirations of a next generation intelligent infrastructure for Railways.
Subrahmanya Venkata Radha Krishna Rao, Vivek Diwanji

The MIH (Media Independent Handover) Contribution to Mobility Management in a Heterogeneous Railway Communication Context: A IEEE802.11/802.16 Case Study

In this paper we propose the use of the IEEE802.21 protocol in the railway context to enhance the highly frequent, repeated and foreseeable handovers between different radio access technologies. This standard specifies IEEE802 media access-independent mechanisms that optimize handovers between heterogeneous IEEE802 systems and between IEEE 802 systems and cellular systems. The global aim is to contribute to develop a seamless layer that provides independence to the application layers from the radio access technology underneath. A case study with two out of the most popular radio access technologies, IEEE802.11 and IEEE 802.16 is undertaken.
Marina Aguado, Jasone Astorga, Jon Matias, Maider Huarte

Multiple Description Coding and Scalable Video Coding Combined with Multiple Input Multiple Output Techniques: Two Strategies to Enhance Train to Wayside Video Transmissions in Tunnels

Video monitoring applications for underground rely on wireless train-to-wayside communication systems which require high data rate as well as high Quality of Service (QoS) level. In order to satisfy both constraints we propose a combined source and channel coding approach in the context of MIMO (Multiple Input Multiple Output) video transmission. In the present case, MIMO transmission is based on the PHY layer of IEEE 802.11n Wi-Fi standard currently deployed in a railway tunnels. Two different strategies are studied: first, the association between Multiple Description Coding (MDC) and a STBC (Space Time Block Code) MIMO scheme is considered when no channel information is available at transmitter side. In the case when perfect channel information is available at transmitter side (CSIT), a Singular Value Decomposition of the MIMO channel is possible. This transmission scheme is then associated with scalable video coding, which consists here in the separation of the scene into different Regions Of Interest (ROI). The creation of the regions of interest is based on the Flexible Macroblock Ordering (FMO) technique introduced in the new H.264/AVC compression standard. The stream associated to the area with the maximal perceptual relevance is transmitted on the eigen-channel with the higher gain. Consequently, this strategy which provides unequal protection against channel errors, allows guaranteeing better robustness and acceptable reconstructed video quality at the control-centre. The two different strategies of transmission have been evaluated thanks to realistic simulations. Two antenna configurations representative of real cases encountered in railway tunnels are considered. The channel model is generated by using the correlation based Kronecker model obtained by computing the channel matrix with a 3D ray tracing tool. Simulation results show that the two proposed solutions allow enhancing the reconstructed video quality compared to conventional transmission schemes with no increase of the transmitted power and of the number of radio access points along the infrastructure, even in tunnels in presence of spatial correlation.
Imade Fahd Eddine Fatani, Yann Cocheril, Crépin Nsiala, Marion Berbineau, François-Xavier Coudoux, Marie Zwingelstein-Colin, Patrick Corlay

Road Track

VANET Architectures and Protocol Stacks: A Survey

Intelligent transportation systems (ITS) provide a set of standards for vehicular communications. The main focus of research activities, within ITS, has been on development of safety, traffic efficiency and infotainment related applications. Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communications are the main research goals of ITS. This paper reviews some popular architectures of VANETs (Vehicular Ad hoc NETworks) i.e., WAVE by IEEE, CALIM by ISO, C2CNet by C2C consortium / GeoNet. It also includes some recent research regarding these standards, specially focusing on Network and MAC layer issues. This paper also discusses safety related application protocols, i.e. WSMP by WAVE, CALM FAST by ISO and C2CNet by C2C consortium. Various recommendations regarding the above protocol stacks are presented. The recommendations are based on different parameters like flexibility, implementation etc.
Sajjad Akbar Mohammad, Asim Rasheed, Amir Qayyum

Behavior Specification of a Red-Light Violation Warning Application – An Approach for Specifying Reactive Vehicle-2-X Communication Applications

Current intelligent transportation systems are based on Vehicle-2-X communication. They accomplish the next level of cooperative advanced driver assistance systems. Since these Vehicle-2-X communication applications are often located in the safety critical areas, high quality demands arise. One part of these requirements is the correct functional behavior. For its validation, a formal specification is required. In this paper, the Red-Light Violation Warning application is used. To specify all the functionality, Continuous-Time State Machines (CTSM) are introduced. Such, a formal specification of a Vehicle-2-X application is given and, consequently, no unintended ambiguities exist furthermore.
Sebastian Röglinger, Christian Facchi

Wireless Protocol Design for a Cooperative Pedestrian Protection System

In the research project Ko-TAG, which is part of the research initiative Ko-FAS, cooperative sensor technology is developed and its benefit for traffic safety applications is evaluated. As a result the new sensor concept shall provide essential input data for next generation driver assistant systems. A secondary radar principle based on communication signals enables localization of objects with simultaneous data transmission. It mainly concentrates on pedestrian and other vulnerable road user (VRU) detection.
This paper describes the architectural approach of the system design, as well as the main characteristics of the physical and data link layers of the proposed wireless protocol. The protocol is designed in such a way that it can be used as an extension to IEEE802.11p/WAVE protocol. The complete protocol is modeled in OPNET network simulator.
Dirk Lill, Manuel Schappacher, Shahidul Islam, Axel Sikora

A Vehicular Mobility Model Based on Real Traffic Counting Data

This paper proposes VehILux, a new vehicular mobility model based on real traffic counting data. It relies on two freely available sources of real information for the country of Luxembourg. The first source is traffic data collected by counting devices located on the Luxembourgian road network, while the second is geographical information about different types of areas: residential, industrial, commercial and other services. VehILux models vehicles commuting around the city of Luxembourg by considering two types of traffic, outer traffic with vehicles entering in the defined geographical area and inner traffic starting from residential zones located inside the geographical area. One part of the collected traffic data is used as input traffic, while another part is used to control the produced traffic and to fine-tune the model. VehILux is coupled with the microscopic road traffic simulator SUMO to produce realistic vehicular traces.
Yoann Pigné, Grégoire Danoy, Pascal Bouvry

Driver-Centric VANET Simulation

Inter-vehicle communication is becoming increasingly relevant in the research and development of novel, innovative vehicular applications. To support the driver in his/her primary driving task in an effective non distracting way, these applications need to be evaluated in a realistic context from a driver’s perspective of the VANET environment. In this paper we propose an innovative driver-centric simulation tool that integrates a VANET simulator with a driving simulator using communication technologies to relay information about the vehicle to the VANET environment and vice versa. The driver behavior is reflected in the VANET simulation system affecting the mobility of the cars in the vicinity and providing the intelligent driving model with new realistic features.
Pedro Gomes, Cristina Olaverri-Monreal, Michel Ferreira, Luís Damas

Simulative Evaluation of the Potential of Car2X-Communication in Terms of Efficiency

Much effort has been put to evaluate the potential of Intelligent Transportation Systems based on Car2X communication with respect to traffic safety. However, harnessing Car2X communication for efficiency purposes also offers potentials in terms of reducing fuel consumption and CO2. In this paper we evaluate these potentials by simulating three different traffic situations. We compare an uncontrolled scenario with one that incorporates a control mechanism that uses the possibility of Car2X communication to influence a single car directly. Our results show a significant potential for a reduction of fuel consumption for some of the traffic scenarios, motivating further research into Car2X communication based traffic control systems.
Benno Schweiger, Philipp Ehnert, Johann Schlichter

Performance Study of an In-Car Switched Ethernet Network without Prioritization

This paper presents the current state of our research in real-time communication of an IP-based in-car network. The Internet Protocol (IP) will serve as convergence layer of different specific in-car network protocols and IEEE 802.3 Ethernet will be the basic technology to transport IP. In this work, we evaluate a legacy switched Ethernet network without any Quality of Service (QoS) mechanisms. While there are arguments for not using QoS mechanisms, we give evidence that communication requirements and service constraints of a more and more streaming intensive in-car network cannot be met without. We argue for a setup with different traffic types: CAN and FlexRay like control messages, camera streaming, video and audio streaming, and bulk traffic. We will also argue for a simple double star topology as a valid assumption where the target architecture of the IP-based in-car network is not yet clear. Setup and simulation will serve as framework and motivation for future work: Analyzing IP-based real-time communication using QoS mechanisms - characterizing traffic classes after IEEE 802.1Q and IEEE 802.1 Audio Video Bridging (AVB).
Hyung-Taek Lim, Kay Weckemann, Daniel Herrscher

Degradation of Communication Range in VANETs Caused by Interference 2.0 - Real-World Experiment

High channel load in vehicle-to-vehicle communication leads to a degradation of the vehicles’ communication range, due to interference and hence packet loss at larger distances. Packet loss results from two or more concurrent transmissions, colliding at receivers located in-between, which is also known as the hidden station problem. In previous works, our simulation study has shown that this packet loss leads to a degradation of 90% of the communication range. In this paper, we confirm the simulation results by real-world measurements. We present a methodology for transferring the simulation scenario to a real-world measurement scenario, able to evaluate the problem of hidden stations. With three radios applying the IEEE 802.11p standard, we measure the degradation of the communication range under interference. In the measurement, we find a degradation of 50 to 70%. On the one hand, there are less collisions due to only one hidden station. On the other hand, we identify that the receiving vehicle as a shadowing object itself is an additional origin for hiding the other station which slightly increases the number of collisions even at close distances.
Robert K. Schmidt, Bernhard Kloiber, Florian Schüttler, Thomas Strang

Real-World Measurements of Non-Line-Of-Sight Reception Quality for 5.9GHz IEEE 802.11p at Intersections

Vehicular Dedicated Short Range Communication (DSRC) promises to reduce accidents by enabling assistance systems such as cross-traffic assistance. This application requires movement information from vehicles that are in Non-Line-Of-Sight (NLOS) due to buildings at intersection corners. DSRC is foreseen to use IEEE 802.11p to deliver regular Cooperative Awareness Messages (CAM). Due to the high operational frequency of 5.9GHz, the ability to provide reliable NLOS reception is often put into question.
We performed an extensive field test specifically targeted to measure DSRC NLOS reception quality. As a novelty, tested intersections were methodically selected to reflect typical urban intersections (in Munich) and the test setup was specifically designed to provide comparable and generalizable results. This allowed us to determine the influence of factors like building positions. The collected data shows that NLOS reception is possible. Reception rates stay mostly well above 50% for distances of 50 meters to intersection center with blocked LOS.
Thomas Mangel, Matthias Michl, Oliver Klemp, Hannes Hartenstein

Interoperability Testing Suite for C2X Communication Components

This paper presents a collection procedures to perform interoperability tests of C2X communication equipment. Following a cross layer approach, interoperability test purposes on radiocommunication equipment, networking layer algorithms, C2X applications and use cases are analyzed. Along with this analysis the main conclusions gathered from the execution of the proposed test cases on a concrete C2X prototype system will be presented.
Fabian de Ponte Müller, Juan María Reveriego Sierra, Bernhard Kloiber, Matthias Röckl, Thomas Strang

Towards Standardization of In-Car Sensors

In this paper we propose standardization of the firmware of in-car sensors to achieve software homogeneity across vendors. Such standardization enhances the reliability of the code by adhering to pre-set practices and definitions. It also increases the throughput of the programmers and opens up hardware platforms to third party developers. We make our case by advocating the use of TinyOS. TinyOS applications, coded in nesC introduce event-driven execution and component-centric design. Furthermore, programming in nesC reduces code size and potential bugs. We use the tyre pressure monitoring system of a car as a case study to illustrate our model. In our implementation, TinySec is employed to address the security and privacy problems that plague current systems. Throughout the paper we show that the use of a common software stack automatically leads to hardware standardization and security improvement.
Zubair Nabi, Atif Alvi, Rashid Mehmood

Secure Automotive On-Board Protocols: A Case of Over-the-Air Firmware Updates

The software running on electronic devices is regularly updated, these days. A vehicle consists of many such devices, but is operated in a completely different manner than consumer devices. Update operations are safety critical in the automotive domain. Thus, they demand for a very well secured process. We propose an on-board security architecture which facilitates such update processes by combining hardware and software modules. In this paper, we present a protocol to show how this security architecture is employed in order to achieve secure firmware updates for automotive control units.
Muhammad Sabir Idrees, Hendrik Schweppe, Yves Roudier, Marko Wolf, Dirk Scheuermann, Olaf Henniger


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