3 Definitions and abbreviations

24.3803GPPMission Critical Push To Talk (MCPTT) media plane controlProtocol specificationRelease 13TS

3.1 Definitions

For the purposes of the present document, the terms and definitions given in 3GPP TR 21.905 [1] and the following apply. A term or definition defined in the present document takes precedence over the definition of the same term or definition, if any, in 3GPP TR 21.905 [1].

Active floor request queue: The floor request queue used by the floor control server to queue received Floor Request messages.

Candidate arbitrator: The queued floor participant in off-network to whom the floor was granted. Once the candidate arbitrator responds to the floor grant, it becomes the current arbitrator.

Controlling MCPTT function: The MCPTT server performing a controlling role.

Conversation: A number of media bursts exchanged between participants in a group call session.

Current arbitrator: The floor participant in off-network currently arbitrating the floor.

Effective priority: The priority decision determined by the floor control server based on multiple input parameters like floor priority, participant type, type of call etc. of the current floor request and of the current participant to which floor is granted if any and the local policy.

MBMS bearer: The service provided by the EPS to deliver the same IP datagrams to multiple receivers in a designated location.

MBMS subchannel: A logical channel which uses resources of an activated and announced MBMS bearer identified by the TMGI of the MBMS bearer and additional parameters, like UDP port, associated to a group or the MBMS subchannel used to e.g. inform when a conversation in a group call is started or ended.

NOTE: In this release of the specifications the UDP port is the only parameter used for enabling the differentiation of media and media plane control packets belonging to different groups over the same MBMS bearer by a receiving MCPTT client.

Media burst: A flow of media from an MCPTT client that has the permission to send media.

Media plane control protocols: Protocols in the media plane used for floor control, pre-established session call control and MBMS subchannel control.

Participating MCPTT function: The MCPTT server performing a participating role.

Passive floor request queue: The floor request queue used by the non-controlling MCPTT function to store received Floor Request messages for monitoring purposes.

For the purposes of the present document, the following terms and definitions given in 3GPP TS 23.179 [5] apply:

Floor control

Floor participant

Floor control server

Group call

MCPTT call

MCPTT server performing a controlling role

MCPTT server performing a participating role

MCPTT user

Mission critical push to talk

Private call

SIP core

For the purposes of the present document, the following terms and definitions given in 3GPP TS 24.379 [2] apply:

Non-controlling MCPTT function of an MCPTT group

For the purposes of the present document, the following terms and definitions given in 3GPP TS 33.179 [14] apply:

Client Server Key (CSK)

Client Server Key Identifier (CSK-ID)

Group Master Key (GMK)

Group Master Key Identifier (GMK-ID)

Multicast Floor Control Key (MKFC)

Multicast Floor Control Key Identifier (MKFC-ID)

Private Call Key (PCK)

Private Call Key Identifier (PCK-ID)

Signalling Protection Key (SPK)

Signalling Protection Key Identifier (SPK-ID)

MBMS SubChannel Control Key (MSCCK)

MBMS SubChannel Control Key Identifier (MSCCK-ID)

For the purposes of the present document, the following terms and definitions given in IETF RFC 3711 [16] apply:

SRTP master key (SRTP-MK)

SRTP master key identifier (SRTP-MKI)

SRTP master salt (SRTP-MS)

3.2 Abbreviations

For the purposes of the present document, the abbreviations given in 3GPP TR 21.905 [1] and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in 3GPP TR 21.905 [1].

AS Application Server

D2D Device to Device

DL Downlink

GCS AS Group Communication Service Application Server

GMK Group Management Key

GMS Group Management Server

GUK-ID Group User Key Identifier

IP Internet Protocol

MBMS Multimedia Broadcast and Multicast Service

MCMC Mission Critical MBMS subchannel Control Protocol

MCPTT Mission Critical Push To Talk

MKI Master Key Identifier

PCK Private Call Key

PCK-ID Private Call Identifier

PTT Push-To-Talk

RFC Request For Comment

RTCP RTP Control Protocol

RTP Real-time Transport Protocol

SRTCP Secure RTCP

SRTP Secure RTP

SSRC Synchronization SouRCe

TEK Traffic-Encrypting Key

TMGI Temporary Mobile Group Identity

UE User Equipment