CEN/TC 278/WG 9 - Dedicated Short Range Communication (DSRC)

The DSRC Standards EN 12253, EN 12795 and EN 12834, which together form a three-layered architecture for DSRC, are designed to encompass a wide range of services for different purposes in order to make the basic DSRC architecture suited for many different applications and for a wide range of possible products and systems.
This document:
-   specifies a physical layer at 5,8 GHz for DSRC as applicable in the field of Road Transport and Traffic Telematics (RTTT).
-   provides requirements for the communication medium to be used for exchange of information between road-side units (RSU) and on-board units (OBU).
-   caters for a communication means to be used by several applications in the RTTT sector.

This European Standard specifies DSRC profiles which provide coherent sets of communication tools for applications based on DSRC. These sets consist of subsets of functionality described in prEN 12253, EN 12795 and EN 12834, out of which a minimum subset is mandatory.
The DSRC Standards prEN 12253, EN 12795 and EN 12834, which together form a three-layered architecture for DSRC, are designed to encompass a wide range of services for different purposes in order to make the basic DSRC architecture suited for many different applications and for a wide range of possible products and systems.
DSRC systems can be built using one-way (downlink) or two-way (interactive) communication. The DSRC profiles described in this European Standard are intended for interactive DSRC systems based on two-way communication and DSRC systems using one-way communication (broadcast services).
While prEN 12253 contains very little variation, EN 12795 and especially EN 12834 describe a wide range of communication services. It has not been considered feasible to assume that any one piece of equipment is designed to implement all of these services. It is often the case that the functionality of the on board unit is more limited than the functionality of the roadside unit.
This European Standard covers
-   Physical Layer parameter values
-   Data Link Layer subsets
-   Application Layer subsets
-   Initialisation procedures
-   Late response procedures
-   Termination procedures

This European Standard specifies the Application Layer Core which provides communication tools for applications
based on DSRC. These tools consist of Kernels that can be used by application processes via service primitives.
The application processes, including application data and application specific functions, are outside the scope of
this European Standard.
The standard is named 'Application Layer' although
- it does not cover all functionality of OSI Layer 7 and
- it includes functionality from lower layers.
This European Standard uses services provided by DSRC Data Link Layer, [EN 12795], and covers functionality of
intermediate layers of the OSI Basic Reference Model [EN ISO/IEC 7498-1].
Figure 1 illustrates the global data flow between the parts of the DSRC stack (Physical, Data Link and Application
Layers) and the application.
The following subjects are covered by this European Standard:
- application Layer structure and framework;
- services to enable data transfer and remote operations;
- application multiplexing procedure;
- fragmentation procedure;
- concatenation and Chaining procedures;
- common encoding rules to translate data from abstract syntax ASN.1, [ISO/IEC 8824-1], into transfer syntax,
[ISO/IEC 8825-2], and vice versa;
- communication initialisation and release procedures;
- broadcast service support;
- DSRC management support including communication profile handling.
It is outside the scope of this European Standard to define a security policy. Some transport mechanisms for
security related data are provided.
NOTE During the lifetime of ENV 12834:1997, no implementation of the Broadcast Pool functionality has become known.
Broadcast Pool functionality is therefore considered untested and is kept in this European Standard for compatibility with the
ENV only.

This European Standard:
-   defines the Data Link Layer of DSRC;
-   is positioned with respect to other related standards by the layers defined in OSI Basic Reference Model [EN ISO/IEC 7498-1] as adopted for DSRC;
-   supports broadcast and half-duplex transmission modes;
-   supports a variety of fixed equipment configurations. It supports configurations where one fixed equipment communicates with one mobile equipment unit, as well as configurations where one fixed equipment can communicate with several mobile equipment units;
-   takes into account that the mobile equipment communicates with the fixed equipment while passing through a limited communication zone;
-   defines neither any specific configuration nor the layout of the communication zone;
-   does not define to what extent different instances of fixed equipment, operating in the vicinity of each other, need to be synchronised with each other;
-   defines parameters to be used in negotiation procedures taking place between fixed equipment and mobile equipment.
By defining two distinct sublayers, namely the medium access control sublayer and the logical link control sublayer, this standard defines:
a)   medium access control procedures for the shared physical medium;
b)   addressing rules and conventions;
c)   data flow control procedures;
d)   acknowledgement procedures;
e)   error control procedures;
f)   services provided to application layer.
The MAC sublayer is specific to the DSRC. The LLC services offered are unacknowledged and acknowledged connectionless services based on [ISO/IEC 8802-2].

This draft European Prestandard: - is a complement to the related standards for the DSRC-layers 1, 2 and 7; - applies to DSRC between fixed equipment at the roadside and mobile equipment in vehicles. This standard does neither apply to vehicle communication nor to communication between different instances of fixed equipment; - defines a number of sets of parameter values to be used in communication between fixed and mobile equipment and assigns a unique identifier to each set. This identifier is to be used in the negotiation and initialisation procedures taking place between fixed and mobile equipment.

This European Prestandard - establishes a common framework for Physical Layer at 5.8 GHz for DSRC for the RTTT sector. - provides requirements for the communication medium to be used for exchange of information between road-side units (RSU) and on-board units (OBU). - does not include associated measurement guidelines for verification of the formulated requirements in this Prestandard. - does not consider any one specific RTTT application, but rather caters for a communication means to be used by several applications in the RTTT sector.

This Standard is applicable to the Application Layer of the Dedicated Short-Range Communication (DSRC) system. Figure 2 illustrates the global data flow between the elements of the DSRC system, (Physical, Data Link and Application Layer) and the application.