9.1.21a Notification/FACCH

3GPP44.018GSM/EDGE Radio Resource Control (RRC) protocolMobile radio interface Layer 3 specificationRelease 17TS

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

The understanding of this message is only required for mobile stations supporting VGCS listening or VBS listening.

This message is sent on the main DCCH, in unacknowledged mode using the RR short protocol discriminator by the network to notify the mobile stations in dedicated mode or in on-going voice broadcast calls or voice group calls on other voice broadcast calls or voice group calls in that cell.

Notification/FACCH messages for VBS or VGCS calls are differentiated by a flag in the call reference.

It is possible in the case of a notification for a ciphered VGCS/VBS call that the notification cannot be described within one Notification/FACCH message. In this case a second message may be used to contain the group call reference, a VSTK_RAND, possibly the CELL_GLOBAL_COUNT and bit 22 of COUNT. The group channel description shall be in the first segment.

Mobile stations not supporting VGCS listening or VBS listening shall ignore this message.

See table 9.1.21a.1.

Message type: NOTIFICATION/FACCH

Significance: dual

Direction: network to mobile station

Table 9.1.21a.1: NOTIFICATION/FACCH message content

<NOTIFICATION FACCH> ::=

<RR short PD : bit> — See 3GPP TS 24.007

<message type : bit(5)> — See 10.4

<short layer 2 header : bit(2)> — See 3GPP TS 44.006

{ 0 <Group Call information>

|1 <Paging Information>

}

{ null | L — Receiver compatible with earlier release

| H — Additions in Release 6 :

{ 0|1 <CELL_GLOBAL_COUNT : bit (2)>

<B22_COUNT : bit> }

{ 0|1 <VSTK_RAND : bit (36)> }

}

{ null | L — Receiver compatible with earlier release

| H — Additions in Release 7 :

<Emergency_Ind : bit (1)>

{ 0|1 <AMR Config : bit (4)> }

{ 0|1 <Paging Cause : bit (2)> }

{ 0|1 < SMS Data Confidentiality Ind : bit (1)>

< SMS Guaranteed Privacy Ind : bit (1)>

}

<spare padding> ;

<Group Call information> ::=

{0|1 <Group Channel Description>} ;

<Priority Uplink Access> ::=

<Priority_Uplink Access:bit==L> — RACH access

| <Priority_Uplink Access:bit==H>; — Group Channel access

<Emergency_Ind> ::=

<Emergency_Ind:bit==L> — emergency mode not set

| <Emergency_Ind:bit==H>; — emergency mode set

<Group Call Reference>

This field is syntactically and semantically equivalent to octets 2-5 and bits 5 to 8 of octet 6 of the Descriptive Group or Broadcast Call Reference information element as defined in 3GPP TS 24.008.

The <Group Channel Description> field is optionally present. When present only the Channel description is provided in the case of non hopping channels or if, when used in the SI10bis Rest Octets, the Frequency List is included. In the case where the channel is hopping (and, in the case of SI10bis Rest Octets, no Frequency List is included) then either a mobile allocation or a frequency short list is provided.

<Group Channel Description> : :=

{ 0

|1 { 0 <Mobile Allocation : <bit string>>

|1 <Frequency Short List : bit(64)>}

};

<bit string> ::= null | bit <bit string> ;

<Channel Description>

This field is syntactically and semantically equivalent to octets 3-5 of the Group Channel Description information element. See sub-clause 10.5.2.14b.

<Frequency Short List>

This field is syntactically and semantically equivalent to octets 1-8 of the Frequency Short List 2 information element. See sub-clause 10.5.2.14a.

<Mobile Allocation>

This field is syntactically and semantically equivalent to octet 2 to n+2 of the Mobile Allocation information element. See sub-clause 10.5.2.21.

The <Paging Information> field may be used to inform the mobile station in Group Receive or in Group Transmit mode that the corresponding mobile identity is paged in that cell.

<Paging Information> ::=

{0|1 <eMLPP priority : bit(3)>} ;

<bit string> ::= null | bit <bit string> ;

<mobile identity>

This field is syntactically and semantically equivalent to octet 2-n of the Mobile Identity information element. See sub-clause 10.5.1.4.

<channel first>

This field is syntactically and semantically equivalent to bits 1 and 2 of the Channel Needed information element. See sub-clause 10.5.2.8.

<eMLPP priority>

This field is coded as the <Priority1> field in the P1 Rest Octets information element. See sub-clause 10.5.2.23.

<VSTK_RAND>

The 36-bit value that is used for derivation of a short term key VSTK, as defined in 3GPP TS 43.020. This parameter is only provided when the group call reference is present and the group call is ciphered.

<CELL_GLOBAL_COUNT>

This field contains the value of the CELL_GLOBAL_COUNT that is used by the VGCS/VBS ciphering mechanism. The value is incremented by one (modulo 4) each time bit 22 of COUNT ( defined in 3GPP TS 43.020) changes from ‘1’ to ‘0’.

<B22_COUNT>

This field contains the value of bit 22 of COUNT (see 3GPP TS43.020) corresponding to the moment when the value of <CELL_GLOBAL_COUNT> was valid.

<Priority Uplink Access>

Indicates the method to be used for priority uplink access.

Bit
L RACH access
H Group Channel.

<Emergency Ind>

This field indicates the status of the emergency mode for the group call.

L Emergency mode not set.

H Emergency mode set.

<AMR Config>

This field indicates the set of AMR codec modes to be used on a group channel using speech version 3. It is coded as the binary representation of the parameter Config-NB-Code of one of the preferred AMR configurations defined in 3GPP TS 28.062 [92].

<Paging Cause>

This field indicates whether the paging contained in the field ‘Paging Information’ is for a mobile terminating call, USSD or short message. Mobile stations shall ignore the contents of this field when the notification does not contain paging information.

bit

2 1

0 0 Paging is for a mobile terminating call

0 1 Paging is for a mobile terminating short message.

1 0 Paging is for a USSD

1 1 Spare – if received, mobile shall treat as for a mobile terminating call

<SMS Data Confidentiality Ind>

This field shall be included periodically (the frequency with which this field is included is implementation dependent) if the network supports the transfer of mobile originated point-to-point short messages via the group call channel. The value is provided by the network (see 3GPP TS 43.068).

If this field is not present the most recently received value in either a Notification/FACCH message or Notification/NCH message shall be used. If no previous value has been received, a default value of "1" shall be assumed.

0 SMS data confidentiality not required.

1 SMS data confidentiality required.

<SMS Guaranteed Privacy Ind>

0 SMS guaranteed privacy not required.

1 SMS guaranteed privacy required.

9.1.21a Notification/FACCH

9.1.21a.1 (void)

9.1.21a.2 (void)

9.1.21a.3 (void)

9.1.21a.4 (void)