ETSI TS 124 581 V18.6.0 (2026-03)

LTE; Mission Critical Video (MCVideo) media plane control; Protocol specification (3GPP TS 24.581 version 18.6.0 Release 18)

RTS/TSGC-0124581vi60

General Information

• Status: Not Published
• Technical Committee: 3GPP CT 1 - MM/CC/SM [lu] (formely CN1)
• Current Stage: 8 - Draft receipt by ETSI Secretariat
• Completion Date: 10-Mar-2026

Standards Content (Sample)

TECHNICAL SPECIFICATION
LTE;
Mission Critical Video (MCVideo) media plane control;
Protocol specification
(3GPP TS 24.581 version 18.6.0 Release 18)

3GPP TS 24.581 version 18.6.0 Release 18 1 ETSI TS 124 581 V18.6.0 (2026-03)

Reference
RTS/TSGC-0124581vi60
Keywords
LTE
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ETSI
3GPP TS 24.581 version 18.6.0 Release 18 2 ETSI TS 124 581 V18.6.0 (2026-03)
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ETSI
3GPP TS 24.581 version 18.6.0 Release 18 3 ETSI TS 124 581 V18.6.0 (2026-03)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 15
1 Scope . 16
2 References . 16
3 Definitions, symbols and abbreviations . 17
3.1 Definitions . 17
3.2 Symbols . 18
3.3 Abbreviations . 18
4 General . 18
4.1 MCVideo media plane overview . 18
4.1.1 Transmission Control . 18
4.1.1.1 General . 18
4.1.1.2 On-network transmission and reception control. 19
4.1.1.3 Off-network transmission control . 20
4.1.1.4 Determine on-network effective priority . 21
4.1.1.5 Determine off-network effective priority . 21
4.1.2 MBMS subchannel control . 22
4.1.2.1 General . 22
4.1.2.2 Start of a MCVideo transmission . 22
4.1.2.3 During a media transmission . 23
4.1.2.4 Ending the transmission . 23
4.1.2.5 MBMS bearer announcement over an MBMS bearer . 23
4.1.3 MBS subchannel control . 23
4.2 Internal structure of media plane control entities . 23
4.2.1 Controlling MCVideo function . 23
4.2.2 MCVideo client . 25
4.2.3 Participating MCVideo function . 27
4.2.3.1 General . 27
4.2.3.2 Internal structure of the participating MCVideo function . 27
4.2.3.3 The roles of the participating MCVideo function . 28
4.2.3.3.1 For the transmission control procedures . 28
4.2.3.3.2 For the use of MBMS bearer procedures . 28
4.2.4 Non-controlling MCVideo function of an MCVideo group . 28
4.3 The media plane control channel . 30
4.3.1 General . 30
4.3.2 Control channel realization . 30
4.3.3 Establishing a media plane control channel . 30
4.3.3.1 General . 30
5 Functional entities . 31
5.1 General . 31
5.2 MCVideo client . 32
5.2.1 Introduction. 32
5.2.2 Transmission participant in on-network mode . 32
5.2.3 Transmission participant in off-network mode . 32
5.3 Controlling MCVideo function . 33
5.4 Participating MCVideo function . 33
6 On-network transmission control . 33
6.1 General . 33
6.2 Transmission participant procedures . 34
6.2.1 Transmission participant procedures at MCVideo session initialization . 34
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6.2.2 Transmission participant procedures at MCVideo call release . 34
6.2.3 Transmission participant procedures at MCVideo call modification . 34
6.2.4 Transmission participant state transition diagram for basic transmission control operation . 34
6.2.4.1 General . 34
6.2.4.2 State: 'Start-stop' . 35
6.2.4.2.1 General . 35
6.2.4.2.2 MCVideo call initiated, originating MCVideo user . 36
6.2.4.2.3 MCVideo call established, terminating MCVideo user . 36
6.2.4.3 State: 'U: has no permission to transmit' . 36
6.2.4.3.1 General . 36
6.2.4.3.2 Send Transmission Request message (Click Transmission send button) . 36
6.2.4.3.3 Void . 37
6.2.4.3.4 Void . 37
6.2.4.4 State: 'U: pending request to transmit' . 37
6.2.4.4.1 General . 37
6.2.4.4.2 Receive Transmission rejected message (R: Transmission rejected) . 37
6.2.4.4.3 Timer T100 (Transmission request) expired . 37
6.2.4.4.4 Timer T100 (Transmission Request) expired N times . 38
6.2.4.4.5 Receive Queue Position Info message (R: Queue Position Info) . 38
6.2.4.4.6 Receive Transmission Granted message (R: Transmission Granted) . 38
6.2.4.4.7 Send Transmission end request message (Click Transmission end button) . 38
6.2.4.5 State: 'U: has permission to transmit' . 39
6.2.4.5.1 General . 39
6.2.4.5.2 Send RTP media packets (S: RTP media) . 39
6.2.4.5.3 Send Transmission end request message (Click Transmission end button) . 39
6.2.4.5.4 Void . 39
6.2.4.5.5 Receive Transmission Revoked message (R: Transmission Revoked) . 39
6.2.4.5.6 Receive Media reception notification message (R: Media Reception notification) . 40
6.2.4.5.7 Receive Transmission End Rquest message (R: Transmission End Request) . 40
6.2.4.6 State: 'U: pending end of transmission' . 40
6.2.4.6.1 General . 40
6.2.4.6.2 Timer T101 (Transmission End Request) expired . 40
6.2.4.6.3 Timer T101 (Transmission End Request) expired N times . 40
6.2.4.6.4 Receive Transmission End Response message (R: Transmission end response) . 41
6.2.4.6.5 Void . 41
6.2.4.7 In any state . 41
6.2.4.7.1 General . 41
6.2.4.7.2 Receive MCVideo call release – step 1 (R: MCVideo call release - 1) . 41
6.2.4.8 State: 'Call releasing' . 41
6.2.4.8.1 General . 41
6.2.4.8.2 Receive MCVideo call release – step 2 (R: MCVideo call release - 2) . 41
6.2.4.9 State: 'U: queued transmission'. 42
6.2.4.9.1 General . 42
6.2.4.9.2 Receive Queue Position Info message (R: Queue Position Info) . 42
6.2.4.9.3 Send Queue Position Request message (S: Queue Position Request) . 42
6.2.4.9.4 Send Transmission end request message (Click Transmission end button) . 42
6.2.4.9.5 void . 43
6.2.4.9.6 Receive Transmission cancel request notify message (R: Transmission Cancel Request
Notify) . 43
6.2.4.9.7 Timer T102 (Transmission Queue Position Request) expired . 43
6.2.4.9.8 Timer T102 (Transmission Queue Position Request) expired N times . 43
6.2.4.9.9 Receive Transmission Granted message (R: Transmission Granted) . 43
6.2.5 Transmission participant state transition diagram for reception control operation . 44
6.2.5.1 General . 44
6.2.5.2 State: 'Start-stop' . 45
6.2.5.2.1 General . 45
6.2.5.2.2 MCVideo call established, terminating MCVideo user . 45
6.2.5.2.3 MCVideo call initiated, originating MCVideo user . 46
6.2.5.3 State: 'U: reception controller' . 46
6.2.5.3.1 General . 46
6.2.5.3.2 Receive Media transmission notification message (R: Media Transmission Notification) . 46
6.2.5.3.3 Send Receive Media Request message (Click video receive button) . 47
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6.2.5.3.4 Receive Transmission end notify message (R: Transmission end notify) . 47
6.2.5.3.5 Receive MCVideo call release – step 1 (R: MCVideo call release - 1) . 47
6.2.5.4 State: 'U: pending request to receive' . 47
6.2.5.4.1 General . 47
6.2.5.4.2 Reception of Receive media response (rejected) message (R: RM response (rejected)) . 47
6.2.5.4.3 Timer T103 (Receive media request) expired . 48
6.2.5.4.4 Timer T103 (Receive Media Request) expired N times . 48
6.2.5.4.5 Reception of Receive media response (granted) message (R: RM response (granted)) . 48
6.2.5.4.6 Media reception request cancel (Click video reception end button) . 49
6.2.5.5 State: 'U: has permission to receive' . 49
6.2.5.5.1 General . 49
6.2.5.5.2 Receive RTP media packets (R: RTP media) . 49
6.2.5.5.3 Media reception end request message (Click video reception end button) . 49
6.2.5.5.4 Receive Media reception override notify message (R: Media Rx override notify) . 50
6.2.5.5.5 Receive Media reception end request message (R: MRE request) . 50
6.2.5.5.6 Void . 50
6.2.5.6 State: 'U: pending reception release' . 50
6.2.5.6.1 General . 50
6.2.5.6.2 Timer T104 (Receive Media Release) expired . 50
6.2.5.6.3 Timer T104 (Receive media release) expired N times . 51
6.2.5.6.4 Receive Media Reception End Response message (R: MRE response) . 51
6.2.5.6.5 Void . 51
6.2.5.7 Void. 51
6.2.5.7.1 Void . 51
6.2.5.7.2 Void . 51
6.2.5.7.3 Void . 51
6.2.5.7.4 Void . 51
6.2.5.8 State: 'U: terminated' . 51
6.2.5.8.1 General . 51
6.2.5.9 State: 'Call releasing' . 52
6.2.5.9.1 General . 52
6.2.5.9.2 Receive MCVideo call release – step 2 (R: MCVideo call release - 2) . 52
6.3 Transmission control server procedures . 52
6.3.1 General . 52
6.3.2 Controlling MCVideo function procedures at MCVideo call initialization . 52
6.3.2.1 General . 52
6.3.2.2 Initial procedures . 52
6.3.2.3 Switching from a non-controlling MCVideo function mode to a controlling MCVideo function

mode . 53
6.3.3 MCVideo transmission control procedures at MCVideo call release . 53
6.3.4 Transmission control server state transition diagram for general transmission control operation . 54
6.3.4.1 General . 54
6.3.4.2 State: 'Start-stop' . 55
6.3.4.2.1 General . 55
6.3.4.2.2 MCVideo call initialization . 56
6.3.4.3 State: 'G: Transmit Idle' . 56
6.3.4.3.1 General . 56
6.3.4.3.2 Enter the 'G: Transmit Idle' state . 56
6.3.4.3.3 Receive Transmission Media Request message (R: Transmission Media Request) . 57
6.3.4.3.4 Timer T2 (Transmit Idle) expired . 57
6.3.4.3.5 Timer T1 (Inactivity) expired . 58
6.3.4.3.6 Receive an implicit Transmission request (R: Implicit Transmission request) . 58
6.3.4.4 State: 'G: Transmit Taken' . 58
6.3.4.4.1 General . 58
6.3.4.4.2 Enter the 'G: Transmit Taken' state. 59
6.3.4.4.5 Receive RTP media packets (R: RTP media) . 59
6.3.4.4.6 Receive Transmission End Request message (R: Transmission End Request) . 59
6.3.4.4.7A Receive Transmission Media Request message without pre-emptive priority (R:
Transmission Media Request) . 60
6.3.4.4.7 Receive Transmission Media Request message with pre-emptive priority (R: pre-emptive
Transmission Media Request) . 60
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6.3.4.4.8 Receive Transmission request message from permitted transmission participant (R:
Transmission Media Request) . 61
6.3.4.4.9 Timer T4 (Transmission Grant) expired . 61
6.3.4.4.10 Timer T4 (Transmission Grant) expired N times . 62
6.3.4.4.11 Permitted MCVideo client release (R: client release). 62
6.3.4.4.12 Receive an implicit Transmission request (R: Implicit Transmission request) . 62
6.3.4.4.13 Send Transmission End Request message (S: Transmission End Request) . 62
6.3.4.5 State: 'G: pending Transmission Revoke' . 63
6.3.4.5.1 General . 63
6.3.4.5.2 Enter the 'G: pending Transmission Revoke' state. 63
6.3.4.5.3 Receive RTP media packets (R: RTP media) . 63
6.3.4.5.4 Receive Transmission End Request message (R: Transmission End Request) . 63
6.3.4.5.5 Void . 64
6.3.4.5.6 Void . 64
6.3.4.5.7 Receive Transmission End Response message (R: Transmission End Response) . 64
6.3.4.6 In any state . 64
6.3.4.6.1 General . 64
6.3.4.6.2 Receive MCVideo call release - 1 . 64
6.3.4.7 State: 'Releasing' . 65
6.3.4.7.1 General . 65
6.3.4.7.2 Receive MCVideo call release - 2 . 65
6.3.5 Transmission control server state transition diagram for basic transmission control operation towards
the transmission participant . 65
6.3.5.1 General . 65
6.3.5.2 State: 'Start-stop' . 67
6.3.5.2.1 General . 67
6.3.5.2.2 SIP Session initiated . 67
6.3.5.3 State: 'U: not permitted and Transmit Idle' . 70
6.3.5.3.1 General . 70
6.3.5.3.2 Enter state 'U: not permitted and Transmit Idle' . 70
6.3.5.3.3 Void . 70
6.3.5.3.4 Receive Transmission Media Request message (R: Transmission Media Request) . 70
6.3.5.3.5 Send Transmission Grant message (S: Transmission Grant) . 70
6.3.5.3.6 Send Transmission Reject message (S: Transmission Reject). 71
6.3.5.3.7 Receive Transmission End Request message (R: Transmission End Request) . 71
6.3.5.3.8 Receive RTP media packets (R: media) . 71
6.3.5.3.9 Receive an implicit Transmission request (R: Implicit Transmission request) . 72
6.3.5.3.10 Send Transmission Idle message (S: Transmit Idle) . 72
6.3.5.4 State 'U: not permitted and transmit taken' . 72
6.3.5.4.1 General . 72
6.3.5.4.2 Enter state 'U: not permitted and Transmit Taken' . 72
6.3.5.4.3 Send Transmission Idle message (S: Transmit Idle) . 73
6.3.5.4.4 Receive Transmission Media Request message (R: Transmission Media Request) . 73
6.3.5.4.5 Receive Transmission End Request message (R: Transmission End Request) . 76
6.3.5.4.6 Receive RTP media packets (R: media) . 78
6.3.5.4.7 Send Transmission Queue Position Info message (R: Transmission Queue Position Request) . 78
6.3.5.4.8 Receive an implicit Transmission request (R: Implicit Transmission request) . 78
6.3.5.4.9 Send Transmission Grant message (S: Transmission Grant) . 78
6.3.5.4.10 Send Media Transmission Notification message (S: Media Transmission Notification) . 79
6.3.5.5 State: 'U: permitted' . 79
6.3.5.5.1 General . 79
6.3.5.5.2 Enter state 'U: permitted' . 79
6.3.5.5.3 Receive Transmission End Request message (R: Transmission End Request) . 79
6.3.5.5.3a Send Transmission End Response message (S: Transmission End Response) . 80
6.3.5.5.4 Send Transmission Idle message (S: Transmit Idle) . 80
6.3.5.5.5 Send Transmission Revoke message (S: Transmission Revoke) . 80
6.3.5.5.6 Receive RTP media packets (R: media) . 80
6.3.5.5.7 Receive Transmission Media Request message (R: Transmission Media Request) . 80
6.3.5.5.8 Send RTP Media (S: media) . 80
6.3.5.5.9 Send Media Transmission Notification message (S: Media Transmission Notification) . 80
6.3.5.5.10 Send Transmission End Request message (S: Transmission End Request) . 81
6.3.5.6 State: 'U: pending Transmit Revoke' . 81
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6.3.5.6.1 General . 81
6.3.5.6.2 Enter state 'U pending Transmit Revoke' . 81
6.3.5.6.3 Timer T3 (Transmission Revoke) expired . 81
6.3.5.6.4 Receive RTP media packets (R: media) . 81
6.3.5.6.5 Receive Transmission End Request message (R: Transmission End Request) . 82
6.3.5.6.5a Send Transmission End Response message (S: Transmission End Response) . 82
6.3.5.6.6 Send Transmission Idle message (S: Transmit Idle) . 82
6.3.5.6.7 Send Media Transmission Notification message (S: Media Transmission Notification) . 82
6.3.5.6.8 Receive Transmission End Response message (R: Transmission End Response) . 83
6.3.5.7 State 'U: not permitted but sends media' . 83
6.3.5.7.1 General . 83
6.3.5.7.2 Enter state 'U: not permitted but sends media' . 83
6.3.5.7.3 Timer T3 (Transmission Revoke) expired . 83
6.3.5.7.4 Receive Transmission End Request message (R: Transmission End Request) . 84
6.3.5.8 In any state . 84
6.3.5.8.1 General . 84
6.3.5.8.2 Receive MCVideo call release – 1. 85
6.3.5.9 State: 'Releasing' . 85
6.3.5.9.1 General . 85
6.3.5.9.2 Receive MCVideo call release - 2 . 85
6.3.6 Transmission control server state transition for general reception control . 85
6.3.6.1 General . 85
6.3.6.2 State: 'Start-stop' . 86
6.3.6.2.1 General . 86
6.3.6.2.2 MCVideo call initialization . 87
6.3.6.3 State: 'Gr: Reception Idle' .
...