Content for  TS 22.179  Word version:  17.1.0

For MCPTT Users, one of the most important performance criteria is the MCPTT Access time (KPI 1). The MCPTT Access time is defined as the time between when an MCPTT User request to speak (normally by pressing the MCPTT control on the MCPTT UE) and when this user gets a signal to start speaking. This time does not include confirmations from receiving users. The MCPTT Access time (KPI 1) does not include the time for an MCPTT User to affiliate to the group. This is a common scenario within public safety, meaning that affiliations to MCPTT Groups are long lived during several working hours. KPI 1 is applicable in both an MCPTT Group call setup request and subsequent MCPTT Requests that are part of the same call. KPI 1 for subsequent MCPTT Requests might take a slightly shorter time than the first MCPTT setup request of the same call due to its potential need of resource allocation in terms of bearer establishment. However from an end user perspective there is no need to differentiate required performance for an MCPPT Group call setup request and subsequent MCPTT Requests. The End-to-end MCPTT Access time (KPI 2) is defined as the time between when an MCPTT User requests to speak (normally by pressing the MCPTT control on the MCPTT UE) and when this user gets a signal to start speaking, including MCPTT call establishment (if applicable) and possibly acknowledgement from first receiving user before voice can be transmitted. Group calls can be set up with or without acknowledgements from receiving users. For MCPTT Private Calls (with Floor control), end-to-end MCPTT Access time (also KPI 2) is measured from the initiating client's Private call request to reception of either a Private Call response for automatic commencement or the MCPTT ringing indication for manual commencement. End-to-end access time for both automatic and manual commencement private calls (KPI 2) is shown in Figure 6.15.3.1-1. The Mouth-to-ear latency (KPI 3) is the time between an utterance by the transmitting user, and the playback of the utterance at the receiving user's speaker. Figure 6.15.3.1-1 illustrates the MCPTT Access time and Mouth-to-ear latency.

[R-6.15.3.2-001] [R-6.15.3.2-002] [R-6.15.3.2-003] [R-6.15.3.2-004] [R-6.15.3.2-005] [R-6.15.3.2-006] [R-6.15.3.2-007] [R-6.15.3.2-008] [R-6.15.3.2-009] [R-6.15.3.2-010] [R-6.15.3.2-011] [R-6.15.3.2-012] [R-6.15.3.2-012a] [R-6.15.3.2-013] [R-6.15.3.2-014] [R-6.15.3.2-015] [R-6.15.3.2-016] [R-6.15.3.2-017] [R-6.15.3.2-019] [R-6.15.3.2-020]

An MCPTT User is able to join or leave already ongoing MCPTT Group calls. Late call entry is the activity when an Affiliated MCPTT Group Member joins an MCPTT Group call in which other Affiliated MCPTT Group Members are already active. The Late call entry time (KPI 4) is the time to enter an ongoing MCPTT Group call measured from the time that a user decides to monitor such an MCPTT Group Call, to the time when the MCPTT UE's speaker starts to play the audio. The performance requirements for Late call entry time only applies to when there is ongoing voice transmitted at the time the MCPTT User joins the call. In a Late call entry there might be an initial lost audio of the voice burst sent to the new Receiving MCPTT Group Member. Figure 6.15.4.1-1 illustrates the Late call entry time.

[R-6.15.4.2-001] [R-6.15.4.2-002] [R-6.15.4.2-002a] [R-6.15.4.2-003] [R-6.15.4.2-004] [R-6.15.4.2-005] [R-6.15.4.2-006] [R-6.15.4.2-007]

Ambient Listening is a feature that allows an authorized MCPTT User, typically a dispatcher, to cause an MCPTT UE to initiate a call 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 remote authorized MCPTT User or can be initiated by a remote authorized MCPTT User who wants to listen to another MCPTT User. The purpose of this feature allows a dispatcher to listen to activities at the Location of the remote MCPTT UE to find out what is happening around that MCPTT UE without providing an indication to the MCPTT User or people around the user (whom the MCPTT User does not want to make aware of this action) that this is happening. This type of call is different from other types of call, as for Ambient Listening audio is only transmitted to one party in the call (i.e., a dispatcher or an authorized MCPTT User that is acting in a similar role to a dispatcher). This is used for stolen MCPTT UEs, monitoring officers, officer safety and particular operations, where it is important that the MCPTT UE does not indicate what is happening.

A Remotely initiated MCPTT Call is a feature that allows an authorized user, typically a dispatcher, to cause a remote MCPTT UE to initiate a call by itself, without its user explicitly initiating the call by depressing the PTT switch. The purpose of this feature allows the dispatcher to listen to activities at the Location of the remote MCPTT UE to find out what is happening around that MCPTT UE. This feature is also known as "Remote Unit Monitoring" in P25 systems. There are two typical use cases for this feature. The first one is the case where a user could have been incapacitated. This could be both accidentally, say a traffic accident, or deliberately, for example a violent attack. In both cases it would be necessary to remotely open the microphone of the MCPTT UE in order to allow another user or a group of users to listen to what is happening to prepare assistance. The communication that is set up is either a Private Call or a Group Call, and the call could optionally be visible to the remote MCPTT UE's user. The second one is the case of a stolen MCPTT UE. Here it is just necessary to activate the radio so that a dispatcher can listen to any background noise or speech in order to make an analysis of the situation. In this situation, the initiation of the call from the remote MCPTT UE, typically a Private Call in that case, is not visible by that MCPTT UE's user. Other use cases, such as undercover operations, discreet surveillance of users or investigations, could exist depending on the missions of the critical communications users and on legislations. The behaviour of the remotely initiated Call is not different from a normal call initiated by the local user. The same rules for resource allocation and interactions with other services apply, but the initiator of the feature can have the capability to request a pre-emptive or high priority for that Call to ensure it is set up even in case of resource congestion or to limit disturbance by other services.

[R-6.16.3.2-001] [R-6.16.3.2-002] [R-6.16.3.2-003] [R-6.16.3.2-004]

Mission critical users currently employ a wide range of narrowband mission critical Push To Talk services. Project 25 (governed by the TIA-102 standards) and TETRA (governed by ETSI standards) are digital public safety grade PTT systems. In addition, "legacy" or "conventional FM" systems are common throughout the world. These systems provide PTT and related services that are analogous to those provided by MCPTT, including group calls, Private Calls, broadcast calls, dynamic group management and other services. The MCPTT Service is intended to interwork with these non-3GPP PTT systems.

[R-6.18.3.2-001] [R-6.18.3.2-002] [R-6.18.3.2-003] [R-6.18.3.2-004] [R-6.18.3.2-005] [R-6.18.3.2-006] [R-6.18.3.2-007] [R-6.18.3.2-008] [R-6.18.3.2-009] [R-6.18.3.2-010] [R-6.18.3.2-011] [R-6.18.3.2-012] [R-6.18.3.2-013] [R-6.18.3.2-014] [R-6.18.3.2-015] [R-6.18.3.2-016] [R-6.18.3.2-017] [R-6.18.3.2-018] [R-6.18.3.2-019] [R-6.18.3.2-020] [R-6.18.3.2-021]

[R-6.18.3.3-001] [R-6.18.3.3-002] [R-6.18.3.3-003] [R-6.18.3.3-004] [R-6.18.3.3-005] [R-6.18.3.3-006] [R-6.18.3.3-007] [R-6.18.3.3-008] [R-6.18.3.3-009] [R-6.18.3.3-010] [R-6.18.3.3-011] [R-6.18.3.3-012] [R-6.18.3.3-013] [R-6.18.3.3-014]

[R-6.18.3.4-001] [R-6.18.3.4-002] [R-6.18.3.4-003] [R-6.18.3.4-004] [R-6.18.3.4-005] [R-6.18.3.4-006] [R-6.18.3.4-007] [R-6.18.3.4-008] [R-6.18.3.4-009] [R-6.18.3.4-010] [R-6.18.3.4-011]

GSM-R, governed by 3GPP standards, is widely and globally used for rail communication. GSM-R offers capabilities analogous to those provided by MCPTT, including group calls, point-to point calls, broadcast calls, dynamic group management and the bearer service for train safety applications.

[R-6.18.4.2-001] [R-6.18.4.2-002] [R-6.18.4.2-002a] [R-6.18.4.2-002b] [R-6.18.4.2-003] [R-6.18.4.2-004] [R-6.18.4.2-005]