This International Standard provides definitions and procedures for the establishment, maintenance and termination of an ITS (intelligent transport systems) communications session within a CALM (communication access for land mobiles) system environment using bi-directional satellite communications.
It defines the operation of the medium management adaptation entity (MMAE), which provides the management interface between a proprietary satellite communications medium and the “ITS station management??. This enables the “ITS station management?? to know the status of the communications medium and control the interface without the need for applications at the ITS station to have any knowledge of the satellite communications interface. The procedures that the “ITS station management?? expects to use are also explained.
NOTE1 CALM links are required for quasi-continuous, prolonged and short-duration communications between vehicles and the roadside, between vehicles, and between mobile equipment and fixed infrastructure points, over medium and long ranges.
This International Standard defines how to connect and disconnect a communication session using satellite communication systems in the context of an application operated within the environment defined in ISO21217. It supports peer-to-peer modes of communication. Support for broadcast satellite systems is defined in ISO13183, which provides a common approach for all broadcast media. It supports satellite communications networks that are interconnected with the public network, as well as those which connect via the internet and those which provide a stand-alone capability.
NOTE2 As there are multiple instantiations of satellite systems, most of which are not interoperable, there is the possibility of several simultaneous satellite sessions, each forming a separate CALM medium (although the differences may only be in software within the on-board equipment).
Wherever practicable, this International Standard has been developed by reference to suitable existing standards, adopted by selection. Application-specific upper layers are not included, but will be driven by application standards (which may not be technology-specific).