scope:

The multi-part deliverable EN 300 396 defines the Terrestrial Trunked Radio (TETRA) Direct Mode Operation (DMO). It specifies the basic air interface, the inter-working between Direct Mode (DM) groups via repeaters, and inter-working with the TETRA Voice plus Data (V+D) system via gateways. It also specifies the security aspects in TETRA DMO, and the intrinsic services that are supported in addition to the basic bearer and teleservices.

The present document applies to the TETRA DMO Mobile Station - Mobile Station (MS-MS) air interface and contains the specifications of the Data Link Layer (DLL) and the network layer according to the ISO model.

It establishes the services, messages and protocols used for voice and circuit mode data calls and short data transfer, starting with the upper layers:

• it defines and specifies the protocol used by the layer 3 entity to communicate across the air interface;

• it defines and specifies the services and protocol used in the DLL.

The normative annexes mainly specify the parameter values used in the protocol.