3GPP43.246Multimedia Broadcast/Multicast Service (MBMS) in the GERANRelease 16Stage 2TS
5.1 Logical channels
For MBMS p-t-m transmission, the traffic data is carried on PDTCH (see 3GPP TS 45.002 ), whereas the control data is carried on PACCH (see 3GPP TS 45.002 ).
A new logical channel is defined, the MPRACH, which may be used during the initial counting procedure (see sub-clause 188.8.131.52). On the MPRACH, Packet Access Bursts or Extended Packet Access Bursts can be transmitted.
5.2 Physical channels
MBMS p-t-m radio bearers are transmitted on PDCH (see 3GPP TS 45.002 ).
On a PDCH it shall be possible to multiplex different MBMS p-t-m radio bearers and GPRS and/or EGPRS TBFs using TFI.
5.2.2 Coding schemes
The existing GPRS and EGPRS coding schemes are used for MBMS.
An MBMS-capable mobile station shall support CS-1 to CS-4 and MCS-1 to MCS-9 in the downlink. A network supporting MBMS may support only some of the coding schemes.
5.2.3 Mapping of MPRACH onto physical channels
The MPRACH may be mapped on any uplink PDCH.
The MPRACH is dynamically allocated in groups of four MPRACH blocks By (y=4x+i, i=0 ,.., 3) corresponding to one PDCH block Bx (x=0,…,11), indicated by a USF. The value of the USF allocated to the mobile station is signalled by the network in the notification message.