ISO 13184-2:2016 specifies the road guidance use cases on the DXM to provide the real-time decision support system to drivers or pedestrians using P-ITS-S. The road guidance protocol (RGP) is an instantiation of the data exchange message (DXM), which represents a generic message to exchange data between ITS stations.

The RGP defines an interoperable service protocol between P-ITS-S and R-ITS-S for exchanging data elements. This part of ISO 13184 specifies the following:

- Reference architecture for real-time decision support system.

This reference architecture provides a general structure for the real-time decision support system and the method of message exchange between the P-ITS-S and the R-ITS-S. This reference architecture is used to build the interconnections between the P-ITS-S and the R-ITS-S.

- Technique of application protocol design for various use cases on a P-ITS-S.

This technique adopts a flexible and extendable protocol design. In many cases, the application protocol for the ITS is designed to provide a set of messages that is dependent on the use cases and the message exchange method. However, it is not easy to enumerate all use cases for some applications. The use cases can be changed or enhanced frequently. For this type of application, the protocol design, depending on the use cases, is not appropriate. This part of ISO 13184 provides a general technique of designing the road guidance application protocol based on the use cases.

- Primitive data element.

The primitive data element will be commonly used to configure the safety warning and parking guide service in the form of speed, location and time.

- Use cases at the road and parking spaces for warning and parking guide.

This part of ISO 13184 describes the use cases applicable to the communication services between the P-ITS-S and the R-ITS-S for the purposes of providing safety warning and parking guidance.

ISO 13184 (all parts) have been aligned according to the requirements specified in ISO 21217, ISO/TS 17419 and ISO/TS 17423.

ISO 13184-2:2016 only specifies the RGP messages based on the DXM definition (see Annex B and Annex C) at real-time. The content of the RGP messages are based on the definition of road guidance use cases as documented in ISO 13184?1.

This part of ISO 13184 implements ITS-SU objects, which is a general reference to ITS application objects, ITS message sets and other objects which may require globally unique identification and registration.

The management of ITS-SU objects is many-fold, e.g. specified in ISO 24102?4, ISO 24102?5, ISO 24102?6, ISO 24102?7, ISO 24102?8 and ISO 24102?9, and in CEN/ISO/TS 17423. This part of ISO 13184 implements authorized and controlled operation of ITS-SU objects, which requires considerations of ITS-SU object identifiers, i.e. ITS-AID, ITS-MsgSetID, ITS-SUID, ITS-SCUID, addresses and protocol identifiers used in the communication protocol stack of an ITS-S, and others.

NOTE The accuracy of the navigation and positioning system as input to the Road Guidance application is important for road guidance but is not part of the ISO 13184 series. Detailed information about crossroads is needed for implementation of Road Guidance applications.