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Digital Multimedia Broadcasting (DMB), Transport Protocol Experts Group (TPEG) and On Board Units (OBU)

DMB

In the METRASYS project, the DMB system architecture with its outstanding mobile usability constitutes the core infrastructure by which the compressed travel data and e.g. incident warnings are transmitted in real-time to the vehicle fleet. The system architecture respects the content sources “floating car data” and further messages sourcing from traffic police and radio station’s community. Data fusion is done on TPEG level as a coding standard for individual information, with optimized digital service configuration for broadcast inside the DAB/DMB standard. Due to well-defined interfaces, all components are open to enhancements in the future and adaptable to other regions if necessary.

TPEK und DAB service chain

METRASYS service chain (Quelle: FIRST)

One DMB broadcast channel has a much greater bandwidth than it is necessary for the data stream generated by the METRASYS project. Therefore, it is very reasonable that in Hefei the already existing DMB channel of the Chinese partner Radio Anhui is used to publish the METRASYS services as well.

The Ministry of Science and Technology (Most) secures financing of the Chinese partners in METRASYS through a Chinese project called “Traffic Information Issuing based on Digital Multimedia Broadcasting Technology”

TPEG

TPEG is a new coding standard for digitally transmitting detailed traffic and journey information and providing road users with comprehensive, up-to-date information. It also enables dynamic data on traffic-relevant weather situations, public transport or car park occupancy levels to be distributed, thus allowing door-to-door support. The new generation of traffic and journey information services uses digital channels, such as the Internet, digitally broadcasted radio and wireless networks. Thanks to compressed coding and therefore low transmission bandwidth requirements, the binary TPEG protocol is particularly suitable for digital radio (DAB/DMB, DRM, DVBx). The transmitted information can be used on mobile platforms as well as in stationary systems or web-based traffic services. Compared with TMC (Traffic Message Channel), TPEG’s architecture is more expressive and flexible, easily scalable and offers encryption methods. It is independent of the transmission channel and the map material used.

OBU

The mobile fleet is equipped with On Board Units (OBU) to take advantage of the METRASYS comprehensive information set. By integration of DMB receiver technology and further TPEG handling capability these devices will help to navigate smoother and producing less pollution.

For that a GPS supported on-board traffic information service terminal is designed. It informs efficiently about the traffic and environmental situation in real time and guides the user to avoid traffic congestion on his trip. All kinds of TPEG messages are displayable and this enriches the driver’s foresight.

Bild einer On Board Unit (OBU)

Figure: View of the graphical user interface of the TrafficViewer for the onboard unit (Source: LUAX/ASEC)

Portability of the traffic information system

Hefei can be seen as a typical example for the dissemination and usage of traffic information in China. The infrastructure chosen here can therefore serve as a model for similar information systems in other Chinese cities. The architecture of the system – beside the addition of the mandatory supervisory body in China - is transferable to even various sites that focus comparable information sources into a unified information propagation using this innovative standards.