Carl-Herbert Rokitansky

Communication architecture and performance analysis of protocols for RTT infrastructure networks and vehicle-roadside communications

A proposal for a communication architecture for road transport telematics (RTT) infrastructure networks is presented. First, the technical approach which has been set up to cope with the relevant subjects is introduced. Then, the communication requirements of RTT applications are considered. Following that, the protocol profile is defined which includes a protocol stack for the vehicle-roadside communications via beacons (DSRC). Thereupon, the protocol evaluation and the co-operation between the beacons and the fixed network ape discussed. Finally, the performance analysis of medium access control (MAC) protocols for the DSRC and for the fixed network are addressed.<<ETX>>

MYCAREVENT- Vehicular Communication Gateway for Car Maintenance and Remote Diagnosis

MobilitY and CollAboRative Work in European Vehicle Emergency NeTworks (MYCAREVENT)1 is an European Project of the 6th Framework Program [1]. MYCAREVENT aims to optimize the European market for automotive services and repair. MYCAREVENT develops and implements new applications and services, which can be seamlessly and securely, accessed using mobile communication. Maintenance situations like car breakdowns or minor failures will happen everywhere. Wherever such an unpleasant situation appears, the driver needs help and advice. The help most likely will be a roadside assistant. MYCAREVENT provides the roadside technician and the driver with mobile communication following an always best connected approach to facilitate the communication between the mobile users within a collaborative work environment. This paper presents the MYCAREVENT project and its communication architecture concept.

Comparison of adaptive medium access control schemes for beacon-vehicle communications

Efficient medium access control schemes are essential for beacon-vehicle communications because of the limited communication zone and randomly arriving vehicles. Several options of data collision recovery mechanisms (such as random delay and persist mechanisms) are presented and evaluated through simulation based on realistic traffic scenarios, antenna configurations and channel characteristics. It is shown that, by choosing the appropriate protocol options and control parameters, high system performance can be achieved. The presented medium access control protocol options are currently being introduced in European standardization bodies for dedicated short-range communications.

Final Assessment of the B-VHF Overlay Concept

B-VHF is a proposal for a future aeronautical communication system in the very high frequency (VHF) band based on an overlay concept, i.e. during the transition phase the B-VHF system shares the same frequency band with legacy VHF systems without interfering with them. In this paper, the feasibility of the overlay concept is evaluated by simulations of the physical and higher layers as well as by laboratory measurements with a demonstrator. Simulation results show that the B-VHF overlay system works in presence of interference from legacy VHF systems. The protocol is designed to allow using the available resources very efficiently and to provide voice and data services with the required quality of service. In addition, the impact of mutual interference between the B-VHF system and legacy VHF systems is evaluated in laboratory test with a simplified B-VHF demonstrator and commercial VHF radios.

Performance analysis and simulation of vehicle-beacon communications protocols

Due to relatively short communication zones, the data link protocols being developed or proposed for vehicle-beacon communications must be carefully evaluated by analysis and simulation, taking antenna configurations, geometry, propagation, and channel characteristics into account. Different methods for media access control and recovering algorithms after message collision are presented and evaluated. Based on the results from analysis and simulation the optimal system parameters and dimensions can be determined. In addition, it is possible to estimate whether not only a single application (e.g., automatic debiting) but several other RTI applications (e.g., route guidance, parking management, etc.) can be supported by a multiservice beacon.<<ETX>>

B-VHF - Selected Simulation Results and Assessment

B-VHF is a proposal for a future aeronautical communication system in the VHF band based on an overlay concept, i.e. during the transition phase the B-VHF system shares the same frequency band with legacy VHF systems without interfering with them. In this paper, the overlay concept is evaluated by simulations of the physical and higher layers. Simulation results show that the B-VHF overlay system works in presence of interference from legacy VHF systems. The protocol is designed to allow using the available resources very efficiently and to provide voice and data services with the required quality of service

Performance of vehicle-roadside communication systems supporting multiple RTI-applications

In this paper, the performance of short-range vehicle-roadside (beacon) communication systems, which support several RTI (Road Transport Informatics) applications at one beacon site, is analysed. After introducing the general requirements of RTI applications, different medium access control protocols and system configurations proposed for standardisation in Europe and North America are presented. Then, the concept of the performance analysis of vehicle-roadside systems based on the simulation in a realistically modelled environment is presented. Simulation results based on an implementation of a mandatory automatic fee collection (AFC) application combined with a dynamic route guidance (DRG) application are analysed in detail (noncompletion rate of transactions, used length of the communication zone, interference between different applications, etc.) and optimal choices of system parameters are presented. It is shown, that a beacon, which is mainly occupied with a mandatory application, such as AFC, is able to provide additional RTI services in order to make best use of the available system capacity and to enhance the benefits for potential users.<<ETX>>

Architecture of an Always Best Connected Vehicular Communication Gateway

MobilitY and CollAboRative Work in European Vehicle Emergency NeTworks (MYCAREVENT) is an European Project of the 6th Framework Program [1], and aims to optimize the European market for automotive after sales services and repair. MYCAREVENT develops innovative applications and services, which can always be accessed seamlessly and securely using mobile communication. Maintenance situations like car breakdowns or minor failures happen everywhere. Wherever such an unpleasant situation appears, the driver needs help and advice - most likely provided by a roadside patrol. To support roadside technicians and drivers with MYCAREVENT products and services, a mobile communication following an always best connected approach facilitates the communication between the mobile users within a collaborative work environment. This paper presents the vehicle communication gateway (VCG) and its protocol architecture developed in MYCAREVENT.

Markov chain analysis of alternative medium access control protocols for vehicle-roadside communications

Vehicle-roadside communication systems provide a very reliable communication link, which is able to support a great variety of ITS (intelligent transport systems) services, such as route guidance, automatic fee collection, driver information, and parking management. Different options for medium access control protocols have been proposed for a standardised communication architecture for vehicle-roadside communications: asynchronous and synchronous frame structures, different collision avoidance and recovery mechanisms (random delay counter vs. persist mechanism) and control parameters (maximum random delay counter, persist value, frame sizes, data rates). The results of a new, detailed analysis based on Markov chains of the proposed options are presented, including the harmonized European standardisation proposal developed within CEN TC 278 WG 9 for the dedicated short-range communications (DSRC) link and the open road frame being proposed for the IVHS communication architecture. Markov models are introduced, which allow one to determine the time span, which is needed in the connection phase to resolve data collisions involving up to three vehicles. Furthermore extended Markov models, which integrate the various models for special situations and are able to describe a complete transaction process, are introduced. As a result of the analysis, guidelines and recommendations for parameter choices are given in order to ensure optimal performance of the communication link in various scenarios and system configurations.

SIMCO2: simulator for performance evaluation of vehicle-beacon and inter-vehicle communication protocols (media access/knowledge-based routing)

An integrated simulation tool, called SIMCO2 (simulation of intelligent maneuvering and communications), for the performance evaluation and verification of short-range vehicle-beacon and intervehicle communication protocols and new road transport informatics (RTI) applications is presented. A realistic mobility model is used to simulate the movement of vehicles (private cars, trucks, buses, etc.) under various environmental conditions (multilane motorways/rural roads with sectionwise speed limits, intersections, etc.) with online graphical display. Based on this model, recently developed communication protocols (media access, logical link control, routing, etc.), the exchange of relevant data between vehicles and roadside beacons, and new RTI applications can be simulated very accurately for the variety of realistic traffic scenarios listed above. SIMCO2 allows one to evaluate the protocol performance of new communication protocols developed for mobile communication networks related to DRIVE, MOBILITY 2000, PROMETHEUS, RACE, etc., and could therefore be a valuable tool for the system design of these networks.<<ETX>>