11.2.41 MBMS MS_ID Assignment

3GPP44.060General Packet Radio Service (GPRS)Mobile Station (MS) - Base Station System (BSS) interfaceRadio Link Control / Medium Access Control (RLC/MAC) protocolRelease 17TS

This message is sent on the PACCH by the network to the mobile station to assign an MS_ID and to provide the timing advance parameters to the mobile station in case of an MBMS radio bearer with an assigned uplink feedback channel. The message can also be used to reassign or delete the MS_ID assigned to the mobile station.

Message type: MBMS MS_ID ASSIGNMENT

Direction: network to mobile station

Classification: non-distribution message

Table 11.2.41.1: MBMS MS_ID ASSIGNMENT information elements

< MBMS MS_ID Assignment message content > ::=

< PAGE_MODE : bit (2) >

{ { 0 < Global TFI : < Global TFI IE > >

| 10 < TLLI / G-RNTI : bit (32) > }

{ 0 — MS_ID is assigned the first time.

< Length of MBMS Bearer Identity : bit (3) >

< MBMS Bearer Identity : bit (val (Length of MBMS Bearer Identity)) >

< MS_ID : bit (5 – val (Length of MBMS Bearer Identity)) >

< Packet Timing Advance : < Packet Timing Advance IE > >

{ 0 | 1 < ALPHA : bit (4) >

{ 0 | 1< GAMMA : bit (5) > }

}

| 1 — MS_ID is reassigned.

< Current MS_ID Expiry Time : bit (16) >

{ 0 — MS_ID is not redefined.

| 1 — MS_ID is redefined.

< Length Indicator of MS_ID : bit (2) >

< MS_ID : bit (val (Length Indicator of MS_ID) + 1) > }

{ 0 | 1 < Packet Timing Advance : < Packet Timing Advance IE > >

{ 0 | 1 < ALPHA : bit (4) >

{ 0 | 1< GAMMA : bit (5) > }

}

}

< padding bits >

! < Non-distribution part error : bit (*) = < no string > > }

! < Address information part error : bit (*) = < no string > > }

! < Distribution part error : bit (*) = < no string > > ;

Table 11.2.41.2: MBMS MS_ID ASSIGNMENT information element details

PAGE_MODE (2 bit field)
This field is defined in sub-clause 12.20.

Global TFI
This information element shall always contain the DOWNLINK_TFI field. The most significant bit(s) of the DOWNLINK_TFI field denote(s) the MBMS Bearer Identity of the MBMS radio bearer the message relates to and the remaining least significant bit(s) denote(s) the MS_ID addressing the mobile station the message relates to. This field is defined in sub-clause 12.10.

TLLI / G-RNTI (32 bit field)
This field contains the TLLI/G-RNTI of the mobile station. This field is encoded as defined in sub-clause 12.16.

MBMS Bearer Identity (1-5 bit field)
This field identifies the MBMS radio bearer this message relates to and is defined in sub-clause 12.34.

MS_ID (1-4 bit field)
This field assigns an identifier to the mobile station, identified by the TLLI, on the MBMS radio bearer identified by the MBMS Bearer Identity, and can also be used to reassign the identifier assigned to the mobile station. This field is defined in sub-clause 12.35.

Packet Timing Advance
This information element is defined in sub-clause 12.12.

ALPHA (4 bit field)
For encoding and description see the Global Power Control Parameters IE.

GAMMA (5 bit field)
The GAMMA field is the binary representation of the parameter GCH for MS output power control in units of 2 dB, see 3GPP TS 45.008. The GAMMA field is coded according to the following table:

bit
5 4 3 2 1
0 0 0 0 0 GCH = 0 dB
0 0 0 0 1 GCH = 2 dB
: : : :
1 1 1 1 0 GCH = 60 dB
1 1 1 1 1 GCH = 62 dB

Current MS_ID Expiry Time
This field contains an expiry time that indicates the frame number during which the mobile station shall consider the current MS_ID as released and, if a new MS_ID is assigned, the new MS_ID as valid. This information element is encoded as the value part of the Starting Time information element specified in 3GPP TS 44.018.