4 MBMS GERAN Architecture

3GPP43.246Multimedia Broadcast/Multicast Service (MBMS) in the GERANRelease 17Stage 2TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.1 General

One new transmission mode exists to provide the MBMS service:

– Point-to-multipoint transmission (p-t-m)

Point-to-multipoint transmission is used to transfer MBMS specific information between the network and an unspecified number of mobile stations. It is used for both broadcast and multicast modes of MBMS.

4.2 GERAN A/Gb mode architecture

4.2.1 Protocol structure

No modifications are required to the GPRS protocol stack (see 3GPP TS 23.060) for MBMS. However, some of the radio protocols in the GERAN will require modifications to support MBMS p-t-m bearers.

4.2.2 void

4.2.3 MBMS reception

Table 4.2.3.1 shows whether a mobile station can support MBMS data reception according to its mode (packet idle mode, packet transfer mode, dedicated mode or dual transfer mode) at the time of the MBMS bearer establishment i.e. immediately prior to MBMS reception.

Table 4.2.3.1: MBMS radio bearer available according to initial MAC mode and MBMS service

Packet idle mode

(GMM-Standby or GMM-Ready)

Packet transfer mode

Dedicated mode

Dual transfer mode

MBMS multicast

p-t-m

p-t-p repair

p-t-p repair (1)

p-t-p repair

MBMS broadcast

p-t-m

Not specified (2)

Not specified (3)

1) A mobile station is moved to dual transfer mode on establishment of a TBF to request an MBMS p-t-p repair.

2) Support is optional in the mobile station.

3) Note that an MBMS broadcast service is only available on a p-t-m radio bearer.

4.3 GERAN Iu mode architecture

4.3.1 Protocol structure

No modifications are required to the GPRS protocol stack (see 3GPP TS 23.060 [1]) for MBMS. However, some of the radio protocols in the GERAN will require modifications to support MBMS p-t-m bearers.

4.3.2 void

4.3.3 MBMS reception

Table 4.3.3.1 shows which type of MBMS radio bearer shall be assigned to the mobile station according to its RRC and MAC states at the time of the MBMS bearer establishment i.e. immediately prior to MBMS reception.

Table 4.3.3.1: MBMS radio bearer available according to initial MAC and RRC states and MBMS service

	RRC-Idle	RRC-GRA_PCH	RRC-Cell_Shared		RRC-Cell_Dedicated
	MAC-Idle	MAC-Idle	MAC-Idle	MAC-Shared	MAC-Dedicated	MAC-DTM
MBMS multicast	p-t-m p-t-p (1)	Not available (2)	p-t-m p-t-p (1)	p-t-p	p-t-p (3)	p-t-p
MBMS broadcast	p-t-m	p-t-m	p-t-m	Not specified (4)	Not specified (5)	Not specified (5)

1) A mobile station is moved to MAC-Shared state on establishment of an MBMS p-t-p radio bearer

2) A mobile station is moved to RRC-Cell_Shared state on establishment of an MBMS radio bearer (p-t-m or p-t-p)

3) A mobile station is moved to MAC-DTM state on establishment of an MBMS p-t-p radio bearer if it has no other PS connections established

4) Support is optional in the mobile station

5) Note that an MBMS broadcast service is only available on a p-t-m radio bearer