9.1.7 Channel release

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

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

This message is sent on the main DCCH from the network to the mobile station to initiate deactivation of the dedicated channel used. See table 9.1.7.1.

Message type: CHANNEL RELEASE

Significance: dual

Direction: network to mobile station

Table 9.1.7.1: CHANNEL RELEASE message content

IEI	Information element	Type / Reference	Presence	Format	length
	RR management Protocol Discriminator	Protocol Discriminator 10.2	M	V	1/2
	Skip Indicator	Skip Indicator 10.3.1	M	V	1/2
	Channel Release Message Type	Message Type 10.4	M	V	1
	RR Cause	RR Cause 10.5.2.31	M	V	1
73	BA Range	BA Range 10.5.2.1a	O	TLV	6 – ?
74	Group Channel Description	Group Channel Description 10.5.2.14b	O (note 1)	TLV	5-13
8x	Group Cipher Key Number	Group Cipher Key Number 10.5.1.10	C	TV	1
Cx	GPRS Resumption	GPRS Resumption 10.5.2.14c	O	TV	1
75	BA List Pref	BA List Pref 10.5.2.1c	O	TLV	3-?
76	UTRAN Freq List	UTRAN Freq List 10.5.2.1d	O	TLV	3-?
62	Cell Channel Description	Cell Channel Description 10.5.2.1b	O	TV	17
77	Cell selection indicator after release of all TCH and SDCCH	Cell selection indicator after release of all TCH and SDCCH 10.5.2.1e	O	TLV	4 – ?
Ax	Enhanced DTM CS Release Indication	Enhanced DTM CS Release Indication 10.5.2.14e	O	TV	1
04	VGCS Ciphering Parameters	VGCS Ciphering Parameters 10.5.2.42b	O	TLV	3-15
78	Group Channel Description 2	Group Channel Description 2 10.5.2.14f	O (note 1)	TLV	13
79	Talker Identity	Talker Identity 10.5.2.65	O	TLV	3-20
7A	Talker Priority Status	Talker Priority Status 10.5.2.64	O	TLV	3
7B	VGCS AMR Configuration	VGCS AMR Configuration 10.5.2.67	O	TLV	3
7C	Individual priorities	Individual priorities 10.5.2.75	O	TLV	3 – ?

NOTE 1: The network may only send either the Group Channel Description or the Group Channel Description 2 element.

9.1.7.1 Group Channel Description / Group Channel Description 2

If a CHANNEL RELEASE is sent to a mobile station which is in dedicated mode and which is involved in a voice group call or has responded to a notification to a voice group call or voice broadcast call, a group channel description (or group channel description 2) may be included, describing the voice group call channel or voice broadcast channel to which the mobile station shall go after the channel release procedure.

Mobile stations not supporting VGCS listening or VBS listening shall ignore the group channel description (or group channel description 2)information element if present.

9.1.7.2 Group Cipher Key Number

This IE may be present only if the Group channel description IE or the Group Channel Description 2 IE is provided. The presence of these IE indicates that the mobile station shall use the Group Cipher Key indicated by the Group Cipher Key Number IE for deciphering on the VGCS or VBS channel. If these IE are not present, no ciphering is applied on the VGCS or VBS channel.

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

9.1.7.3 UTRAN Freq List

This IE should only be sent to UTRAN capable mobile station. This information element is used to describe the UTRAN frequencies used by the network.

9.1.7.4 Cell Channel Description

This IE may be present if the following conditions are satisfied:

– the CHANNEL RELEASE message is ordering the release of the uplink to the originator or to the talker of a VGCS call over a dedicated channel; and

– the Group Channel Description IE is included in the message and is describing a hopping channel.

It shall not be included in any other case.

Mobile stations not supporting VGCS talking or VGCS originating shall ignore this information element if present.

9.1.7.5 VGCS Ciphering Parameters

This information element is only applicable to a VGCS mobile station. It is only included if the group channel is ciphered.

9.1.7.6 Talker Identity

This information element is only applicable to a VGCS talking subscriber. Mobile stations not supporting VGCS talking shall ignore this information element if present.

9.1.7.7 Talker Priority Status

This information element is only applicable to a VGCS talking subscriber. Mobile stations not supporting VGCS talking shall ignore this information element if present.

9.1.7.8 VGCS AMR Configuration

This information element is only applicable to a VGCS talking subscriber. Mobile stations not supporting VGCS talking shall ignore this information element if present.

9.1.7.9 Individual priorities

This information element is sent to provide MS-specific priorities for priority-based cell reselection. The individual priorities shall override the priorities received through system information or individual priorities received previously. The timer T3230 is used to control the availability of the individual priorities.