3 Definitions, symbols and abbreviations

24.3793GPPMission Critical Push To Talk (MCPTT) call controlProtocol specificationRelease 18TS

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 defined in the present document takes precedence over the definition of the same term, if any, in 3GPP TR 21.905 [1].

An MCPTT user is affiliated to an MCPTT group: The MCPTT user has expressed interest in an MCPTT group it is a member of, and both the MCPTT server serving the MCPTT user and the MCPTT server owning the MCPTT group have authorized the MCPTT user’s interest in the MCPTT group communication.

An MCPTT user is affiliated to an MCPTT group at an MCPTT client: The MCPTT user is affiliated to the MCPTT group, the MCPTT client has a registered IP address for an IMPU related to the MCPTT ID, and the MCPTT server serving the MCPTT user has authorised the MCPTT user’s interest in the MCPTT group at the MCPTT client.

Affiliation status: Applies for an MCPTT user to an MCPTT group and has one of the following states:

a) the "not-affiliated" state indicating that the MCPTT user is not interested in the MCPTT group and the MCPTT user is not affiliated to the MCPTT group;

b) the "affiliating" state indicating that the MCPTT user is interested in the MCPTT group but the MCPTT user is not affiliated to the MCPTT group yet;

c) the "affiliated" state indicating that the MCPTT user is affiliated to the MCPTT group and there was no indication that MCPTT user is no longer interested in the MCPTT group; and

d) the "deaffiliating" state indicating that the MCPTT user is no longer interested in the MCPTT group but the MCPTT user is still affiliated to the MCPTT group.

Ambient listening call: a call type allowing an authorized MCPTT user to cause an MCPTT client to initiate a communication which results in no indication on the MCPTT UE that it is transmitting. Ambient listening can be initiated by an authorized MCPTT user who wants to be listened to by another authorized MCPTT user or can be initiated by an authorized MCPTT user who wants to listen to another MCPTT user.

Ambient listening client role: the role of an MCPTT client in an ambient listening call, which can be that of:

a) the "listening MCPTT user"; or

b) the "listened-to MCPTT user".

Ambient listening type: the type of an ambient listening call from the perspective of the relationship of the initiator of the call to the user being listened to. The two types of ambient listening call are:

a) "remote-init", indicating that the listening MCPTT user initiated the call; and

b) "local-init", indicating that the listened-to MCPTT user initiated the call.

First-to-answer call: A call initiated by one user towards a list of other users with the intention to establish an MCPTT private call or MCPTT emergency private call, with one of the users in the list of users.

Group document: when the group is not a regroup based on a preconfigured regroup, the term "group document" used within the present document refers to the group document for that group within the GMS as specified in 3GPP TS 24.481 [31]; when the group is a regroup based on a preconfigured group, the term "group document" used within the present document refers to the group document for the preconfigured group as specified in 3GPP TS 24.481 [31] restricted to the users or groups included in the regroup stored by the MCPTT server at the time of the regroup creation, see clause 16.

Group identity: An MCPTT group identity or a temporary MCPTT group identity.

In-progress emergency private call state: the state of two participants when an MCPTT emergency private call is in progress.

In-progress imminent peril group state: the state of a group when an MCPTT imminent peril group call is in progress.

Listening MCPTT user: the MCPTT user in an ambient listening call receiving the media transmission from the listened-to MCPTT user;

Listened-to MCPTT user: the MCPTT user in an ambient listening call who is being listened to, may or may not be aware of being listened to depending on ambient listening type of the call.

MCPTT client ID: is a globally unique identification of a specific MCPTT client instance. MCPTT client ID is a UUID URN as specified in IETF RFC 4122 [67].

MCPTT emergency alert state: MCPTT client internal perspective of the state of an MCPTT emergency alert.

MCPTT emergency group state: MCPTT client internal perspective of the in-progress emergency state of an MCPTT group maintained by the controlling MCPTT function.

MCPTT emergency group call state: MCPTT client internal perspective of the state of an MCPTT emergency group call.

MCPTT emergency private call: MCPTT emergency call between two MCPTT users that is initiated as a private call or a first-to-answer call with emergency indication, or without emergency indication when the MCPTT emergency state is already set,

MCPTT emergency private call state: MCPTT client internal perspective of the state of an MCPTT emergency private call.

MCPTT emergency private priority state: MCPTT client internal perspective of the in-progress emergency private call state of the two participants of an MCPTT emergency private call maintained by the controlling MCPTT function.

MCPTT imminent peril group call state: MCPTT client internal perspective of the state of an MCPTT imminent peril group call.

MCPTT imminent peril group state: MCPTT client internal perspective of the state of an MCPTT imminent peril group.

MCPTT private call: MCPTT call between two MCPTT users that is initiated as a private call or a first-to-answer call.

MCPTT private emergency alert state: MCPTT client internal perspective of the state of an MCPTT private emergency alert targeted to an MCPTT user.

MCPTT speech: Conversational audio media used in mission critical push to talk systems as defined by 3GPP TS 22.179 [2] and 3GPP TS 23.379 [3].

Media-floor control entity: A media control resource shared by participants in an MCPTT session, controlled by a state machine to ensure that only one participant can access the media resource at the same time.

N2: The maximum number of simultaneous affiliations to MCPTT groups that the MCPTT user may have. The value of N2 is specified in the <MaxAffiliationsN2> element of the <Common> element of the MCPTT user profile and corresponds to the parameter Nc2 specified in 3GPP TS 22.280 [76].

Private call: A call initiated by one user towards one other user with the intention to establish an MCPTT private call or MCPTT emergency private call.

Private Call Call-Back: A mechanism for a requesting MCPTT client to request a targeted MCPTT client to initiate an MCPTT private call with the requesting MCPTT client (at earliest convenience).

Remote change of an MCPTT user’s selected group: A mechanism allowing an authorised user to remotely change the selected group of another MCPTT user.

Temporary MCPTT group identity: A group identity representing a temporary grouping of MCPTT group identities formed by the group regrouping operation as specified in 3GPP TS 24.481 [31].

Trusted mutual aid: A business relationship whereby the Partner MCPTT system is willing to share the details of the members of an MCPTT group that it owns with the Primary MCPTT system.

Untrusted mutual aid: A business relationship whereby the Partner MCPTT system is not willing to share the details of the members of an MCPTT group that it owns with the Primary MCPTT system.

User Requested Application Priority: The requested priority as defined in 3GPP TS 23.280 [82]. How the server determines the priority for the requested communication based on requested priority and in combination with other factors is up to MCPTT server implementation.

Functional alias status: Applies for the status of a functional alias for an MCTT user and has one of the following states:

a) the "not-activated" state indicating that the MCPTT user has not activated the functional alias;

b) the "activating" state indicating that the MCPTT user is interested in using the functional alias but the functional alias is not yet activated for the MCPTT user;

c) the "activated" state indicating that the MCPTT user has activated the functional alias;

d) the "deactivating" state indicating that the MCPTT user is no longer interested in using the functional alias but the functional alias is still activated for the MCPTT user; and

e) the "take-over-possible" state indicating that the MCPTT user interested in the functional alias is allowed to take-over the functional alias although the functional alias is already activated and used by another MCPTT user.

For the purposes of the present document, the following terms and definitions given in 3GPP TS 22.179 [2] apply:

In-progress emergency

MCPTT emergency alert

MCPTT emergency group call

MCPTT emergency state

Partner MCPTT system

Primary MCPTT system

For the purpose of the present document, the following terms and definitions given in 3GPP TS 24.380 [5] apply:

MBMS subchannel

For the purpose of the present document, the following terms and definitions given in 3GPP TS 23.379 [3] apply:

Pre-selected MCPTT user profile

Selected MCPTT user profile

For the purpose of the present document, the following terms and definitions given in 3GPP TS 33.180 [78] apply:

Client Server Key (CSK)

Multicast Floor Control Key (MKFC)

Multicast Signalling Key (MuSiK)

Multicast Signalling Key Identifier (MuSiK-ID)

MBMS subchannel control key (MSCCK)

MBMS subchannel control key identifier (MSCCK-ID)

Private Call Key (PCK)

Signalling Protection Key (SPK)

XML Protection Key (XPK)

For the purpose of the present document, the following terms and definitions given in 3GPP TS 22.280 [76] apply:

Functional alias

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].

CID Context ID

CSK Client-Server Key

ECGI E-UTRAN Cell Global Identification

IPEG In-Progress Emergency Group

IPEPC In-Progress Emergency Private Call

IPIG In-Progress Imminent peril Group

MBMS Multimedia Broadcast and Multicast Service

MBSFN Multimedia Broadcast multicast service Single Frequency Network

MCPTT Mission Critical Push To Talk

MCPTT group ID MCPTT group Identity

MC Mission Critical

MCS Mission Critical Service

MEA MCPTT Emergency Alert

MEG MCPTT Emergency Group

MEGC MCPTT Emergency Group Call

MEPC MCPTT Emergency Private Call

MEPP MCPTT Emergency Private Priority

MES MCPTT Emergency State

MIME Multipurpose Internet Mail Extensions

MIG MCPTT Imminent peril Group

MIGC MCPTT Imminent peril Group Call

MONP MCPTT Off-Network Protocol

MPEA MCPTT Private Emergency Alert

NAT Network Address Translation

PCC Policy and Charging Control

PCCB Private Call Call-Back

PLMN Public Land Mobile Network

QCI QoS Class Identifier

ROHC Robust Header Compression

RTP Real-time Transport Protocol

SAI Service Area Identifier

SDP Session Description Protocol

SIP Session Initiation Protocol

SPK Signalling Protection Key

SSRC Synchronization SouRCe

TGI Temporary MCPTT Group Identity

TMGI Temporary Mobile Group Identity

UE User Equipment

URI Uniform Resource Identifier

XPK XML Protection Key