5.3.4 Broadcast/Multicast Control – Services and functions

25.3013GPPRadio interface protocol architectureTS

This subclause provides an overview on services and functions provided by the BMC sublayer. A detailed description of the BMC protocol is given in [10].

5.3.4.1 BMC Services

The BMC-SAP provides a broadcast/multicast transmission service in the user plane on the radio interface for common user data in unacknowledged mode.

5.3.4.2 BMC Functions

– Storage of Cell Broadcast Messages.
The BMC stores the Cell Broadcast messages received over the CBC-RNC interface for scheduled transmission.

– Traffic volume monitoring and radio resource request for CBS.
At the UTRAN side, the BMC calculates the required transmission rate for Cell Broadcast Service based on the messages received over the CBC-RNC interface, and requests for appropriate CTCH/FACH resources from RRC.

– Scheduling of BMC messages.
The BMC receives scheduling information together with each Cell Broadcast message over the CBC-RNC-interface. Based on this scheduling information, at the UTRAN side, BMC generates schedule messages and schedules BMC message sequences accordingly. At the UE side, BMC evaluates the schedule messages and indicates scheduling parameters to RRC, which are used by RRC to configure the lower layers for CBS discontinuous reception.

– Transmission of BMC messages to UE.
This function transmits the BMC messages (Scheduling and Cell Broadcast messages) according to schedule.

– Delivery of Cell Broadcast messages to upper layer (NAS).
This functions delivers the received Cell Broadcast messages to upper layer (NAS) in the UE. Only non-corrupted Cell Broadcast messages are delivered.