A3 MBMS Phase 3

25.3463GPPIntroduction of the Multimedia Broadcast/Multicast Service (MBMS) in the Radio Access Network (RAN)Release 17Stage 2TS

This phase starts after initial MBMS radio bearer setup and ends when UTRAN receives the MBMS "session stop" from CN.

In this phase, UTRAN transmits the data for the MBMS service received from CN using, if any, the established radio bearer. If there is no set-up radio bearer, UTRAN waits for service delivery request from UE. Recounting and radio bearer reconfiguration may be performed during this phase.

UTRAN behaviour in this phase can be divided into three states: no transmission, p-t-p transmission, and p-t-m transmission. Each cell belonging to the same MBMS service area may be in any of three states. With the variation of the number of UEs, the state of a cell may change between the three states. UTRAN may broadcast the state of each cell.

1) No Transmission: In this state of a cell, there is no established radio bearer because there is no UE who wants to receive the service. An MBMS-joined (or MBMS-interested in broadcast mode) UE in idle mode that moves into the cell of this state requests service delivery to UTRAN.

2) P-t-p Transmission: In this state of a cell, p-t-p radio bearer is established. A UE that has joined (or interested in broadcast mode) an MBMS service may receive MBMS data over p-t-p radio bearer if there is MBMS data to receive.

3) P-t-m Transmission: In this state of a cell, p-t-m radio bearer is established. A UE that has joined (or interested in broadcast mode) an MBMS service may receive MBMS data over p-t-m radio bearer if there is MBMS data to receive.