The Transport Protocol Experts Group (TPEG) is a data protocol suite for traffic and travel related information. TPEG can be carried over different transmission media (bearers), such as digital broadcast or cellular networks (wireless Internet). TPEG applications include, among others, information on road conditions, weather, fuel prices, parking or delays of public transport.
Overview
TPEG is a set of data protocols for carrying traffic & travel related information, comprising a range of different applications as well as basic building blocks to manage the transmission of the applications themselves, such as the handling of different messages belonging to a given application, grouping applications into data frames, or the updating and cancellation of messages. TPEG can be carried over different transmission media (bearers), such as digital broadcast or cellular networks (wireless Internet). TPEG applications include, among others, information on road conditions, weather, fuel prices, parking or delays of public transport.
History
The Transport Protocol Experts Group was started in 1997 by the
European Broadcasting Union
The European Broadcasting Union (EBU; french: Union européenne de radio-télévision, links=no, UER) is an alliance of Public broadcasting, public service media organisations whose countries are within the European Broadcasting Area or who ar ...
(EBU). Work carried on under the auspices of the EBU until 2007, when the group merged with another group working on the
Traffic Message Channel (TMC) protocol, hosted b
ERTICO - ITS Europeand with th
Mobile.Infoproject, where first prototypes of TPEG technology was tested under realistic driving conditions in various in-car navigation systems by a number of car manufacturers and their suppliers. Today, development work is carried out by the
Traveller Information Services Association (TISA), who now also looks after the Alert-C standards used for implementing RDS-TMC services.
In the early days of the Transport Protocol Experts Group, the plan was to develop applications that could extend traffic information services far beyond existing technologies, such as RDS-TMC or proprietary protocols. Further, TPEG should include multi-modal traveller information services, facilitating roaming of travellers between different modes of transportation, e.g. between individual transportation (using a car) and public transportation (bus, subway, trains, ...). It all started with a Road Traffic Message (RTM) application, which was soon complemented by a Public Transport Information (PTI) application, which both shared a common native TPEG Location Referencing method.
TPEG RTM was intended as the ''"one size fits all"'' application. However, early implementations soon showed that the RTM structure was too broad to be used in navigation systems as a replacement for TMC. This first generation TPEG applications (TPEG generation 1, or ''TPEG1'') also provided only a binary encoding, having in some cases a separate specification for the mapping to an XML encoding. Consequently, a revision of both the general information modelling style and the design approach was done, moving TPEG towards more clearly defined and separated applications for specific use cases and a top-down data modelling approach. This second generation TPEG applications (TPEG generation 2, or TPEG2) is now specified with an UML model, from which automatically both a binary encoding and XML encoding are derived. A TPEG2 application specification includes both the binary and XML encodings as integral part of the specification.
With the first TPEG2 TEC application, a breakthrough was achieved in a sense that both service providers and device manufacturers accepted TPEG2 as ''THE'' successor to TMC and deployments were rolled out in many countries.
Both TPEG1 and TPEG2 are standardized with the
International Organization for Standardization
The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Ar ...
as ISO/TS 18234 (TPEG1) and ISO/TS 21219 (TPEG2). TPEG1 is now considered a legacy system and the implementation of new services based on TPEG1 is discouraged.
Technology
TPEG defines specifications for providing highly accurate traffic- and traveller information of many kinds. TPEG allows the transfer of data via different bearers e.g. digital broadcast or internet. In fact, today this is mainly used to inform travellers on roads, train tracks or even pedestrians. Information for a convenient journey e.g. on road conditions, weather, fuel prices, parking or delays of public transport are coded in TPEG.TPEG is a protocol with containers which carry specific content, for each service on a specific content so called ‘applications’ are defined in a separate technical specification. TPEG is designed to be modern and flexible, it is even more future proof, easy to adapt towards new trends, needs and conditions. Selecting the right applications and technical implementation profile, allows provision of safety relevant information to all travellers on time, accurately and precisely. Due to this major benefit, TPEG is also welcomed by regulators and public authorities. TPEG based products are already available in several European and Asian and American markets from different suppliers. Such products range from content creation/management over encoder/decoder equipment, test equipment and receiver/navigation devices to numerous services that are online worldwide. Further, encryption solutions
are available for commercial services.
TPEG design philosophy
TPEG is developed in a top-down fashion based on modeling use cases in the
Unified Modeling Language
The Unified Modeling Language (UML) is a general-purpose, developmental modeling language in the field of software engineering that is intended to provide a standard way to visualize the design of a system.
The creation of UML was originally m ...
(UML). Based on the UML modeling, two encoding versions are derived:
*
Extensible Markup Language
Extensible Markup Language (XML) is a markup language and file format for storing, transmitting, and reconstructing arbitrary data. It defines a set of rules for encoding documents in a format that is both human-readable and machine-readable. T ...
(XML) encoding – This format is human- and machine-readable and it can be easily rendered in navigation devices by parsing the XML structure. It is further backwards compatible in a way that new XML tags can be included in a given application, which would be simply skipped by older device populations that do not recognize these tags. New device populations can however benefit from the new features.
*
Binary encoding – This format is not human-readable, but much more compact than its XML representation. Binary encoding is therefore frequently used when the available bandwidth is small and a compact encoding of services is of the essence.
TPEG core principles
The following principles are considered as core in the development of the TPEG protocol, structure and semantics (see and
).
TPEG:
* is designed for unidirectional (
broadcast
Broadcasting is the distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum ( radio waves), in a one-to-many model. Broadcasting began ...
) and bi-directional communication channels (e.g.
IP)
* binary versions are
byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable unit ...
-oriented
* provides a protocol structure with asynchronous framing and a hierarchical data frame structure
* includes
CRC error detection capabilities on different protocol levels
* assumes that the underlying communication
layers
Layer or layered may refer to:
Arts, entertainment, and media
* ''Layers'' (Kungs album)
* ''Layers'' (Les McCann album)
* ''Layers'' (Royce da 5'9" album)
*"Layers", the title track of Royce da 5'9"'s sixth studio album
*Layer, a female Maveric ...
provide
error correction
In information theory and coding theory with applications in computer science and telecommunication, error detection and correction (EDAC) or error control are techniques that enable reliable delivery of digital data over unreliable communica ...
* uses a transparent data channel
* facilitates transmission of service provider names, service names, network information, etc.
* permits the use of encryption
mechanisms, e.g. for restricting access to commercial services
TPEG additional capabilities
TPEG:
* supports dynamic ("on-the-fly") location referencing methods and therefore does not need a preloaded location database (e.g. TMC Location Tables)
* offers rich content encoding
* is language independent
* facilitates client device filtering of service content
* is designed to support "thick" and "thin" client devices
* provides adaptation layers for different communication bearers
TPEG2 applications
TPEG services worldwide
Broadcast services
Mobile broadband (IP based) services
Hybrid services
See also
*
Transport standards organisations Transport standards organisations is an article transport Standards organisations, consortia and groups that are involved in producing and maintaining standards that are relevant to the global transport technology, transport journey planning and tra ...
*
Traveller Information Services Association (TISA)
References
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External links
Traveller Information Services Association (TISA)Institut für Rundfunktechnik (IRT)BEST ConsortiumWorld DAB ForumWeCanTPEG.com
Broadcasting
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