ETSI - European Telecommunications Standards Institute
引用标准
1444
适用范围
The present document defines the Air Interface (AI) for the Terrestrial Trunked Radio (TETRA) system supporting Voice plus Data (V+D) conventional access (CA) and direct access (DA) and contains the specifications of the physical layer@ the data link layer and the network layer according to the ISO model. First@ it establishes the TETRA radio aspects (layer 1): ? it defines and specifies the modulation; ? it defines and specifies the radio transmission and reception; ? it defines and specifies the synchronization; ? it defines and specifies the channel coding; ? it defines and specifies the channel multiplexing; ? it defines and specifies the control over the radio link. Secondly@ it establishes the services@ messages and protocols used for voice and circuit mode data transfer@ starting with the upper layers: ? it defines and specifies the services provided by the CC sub-entity; ? it defines and specifies the services provided by the SS sub-entity; ? it defines and specifies the services provided by the SDS sub-entity; ? it defines and specifies the protocol used by the Circuit Mode Control Entity (CMCE) to communicate across the air interface in order to offer the services of the Call Control (CC)@ Supplementary Service (SS) and Short Data Service (SDS) sub-entities; ? it defines and specifies the services and protocol used for the management of the users' mobility inside and across TETRA networks@ namely the ones of the Mobility Management (MM) entity and the MLE; ? it defines and specifies the services and protocol used in the data link layer subdivided in two sub-entities@ the Logical Link Control (LLC) and the Medium Access Control (MAC) entities. Thirdly@ it establishes the services@ messages and protocols used for packet data transfer: ? it defines and specifies the services provided by the Sub-Network Specific Data Control Protocol (SNDCP) sub-entity; ? it defines and specifies the protocol used by Sub-Network Specific Data Control Protocol (SNDCP).