ETSI TR 126 989 V17.0.0 (2022-05)

LTE; 5G; Mission Critical Push To Talk (MCPTT); Media, codecs and Multimedia Broadcast/Multicast Service (MBMS) enhancements for MCPTT over LTE (3GPP TR 26.989 version 17.0.0 Release 17)

RTR/TSGS-0426989vh00

General Information

• Status: Not Published
• Technical Committee: 3GPP SA 4 - Codec
• Current Stage: 12 - Completion
• Completion Date: 04-May-2022

Standards Content (Sample)

ETSI TR 126 989 V17.0.0 (2022-05)






TECHNICAL REPORT
LTE;
5G;
Mission Critical Push To Talk (MCPTT);
Media, codecs and Multimedia Broadcast/Multicast Service
(MBMS) enhancements for MCPTT over LTE
(3GPP TR 26.989 version 17.0.0 Release 17)

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3GPP TR 26.989 version 17.0.0 Release 17 1 ETSI TR 126 989 V17.0.0 (2022-05)

Reference
RTR/TSGS-0426989vh00
Keywords
5G,LTE
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ETSI

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3GPP TR 26.989 version 17.0.0 Release 17 2 ETSI TR 126 989 V17.0.0 (2022-05)
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ETSI

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3GPP TR 26.989 version 17.0.0 Release 17 3 ETSI TR 126 989 V17.0.0 (2022-05)
Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
1 Scope . 6
2 References . 6
3 Abbreviations . 7
4 Reference Model . 7
5 Key Issues for Supporting MCPTT . 8
5.1 Key Issue#1: Codec for MCPTT . 8
5.1.1 Review of Codec Alternatives and their Relative Perceptual Performance . 8
5.1.1.1 Overview of the 3GPP Codec Comparison . 8
5.1.1.2 Narrowband Comparison vs AMR . 8
5.1.1.3 Wideband Comparison vs AMR-WB . 12
5.1.1.4 Super-wideband EVS and Relationships to Other Bandwidths . 16
5.1.1.5 Comparison of the 3GPP Codecs to TETRA . 17
5.1.1.6 Comparison of Performance over MCPTT Bearers . 20
5.1.1.6.1 "HD-Voice" AMR-WB performance over 3GPP networks . 20
5.1.1.6.2 MCPTT Bearers. 21
5.1.1.6.3 AMR-WB and EVS Performance over the MCPTT Bearers . 23
5.1.1.6.3.1 EVS Speech Quality . 23
5.1.1.6.3.2 Unicast bearer . 28
5.1.1.6.3.3 MBMS bearer . 28
5.1.1.6.3.4 LTE-D bearer . 31
5.1.1.6.4 Conclusions . 37
5.1.1.7 Listening effort evaluation of AMR-WB and EVS under impaired channels . 38
5.1.1.7.1 Test setup . 38
5.1.1.7.2 Test results . 38
5.1.2 Review of the Codec Alternatives and their Relative Speech Intelligibility in Clean and Low SNRs . 41
5.1.2.1 Speech Intelligibility . 41
5.1.2.1.1 MCPTT bearers – speech intelligibility . 48
5.1.2.1.2 Conclusions . 53
5.1.3 Review of Codec Alternatives and their Relative Complexity . 54
5.1.4 Recommended requirements . 55
5.1.5 GAP Analysis and Evaluation . 56
5.1.5.1 Requirements on Audio/Voice Quality . 56
5.1.5.2 Discrete/Ambient Listening and Remotely Initiated Monitoring . 56
5.1.5.3 Noise Reduction . 56
5.1.5.4 Common Codec Constraints of MCPTT . 56
5.1.5.5 Requirements on Transcoding Functions in the Network . 57
5.1.6 Criteria with respect to MCPTT codec selection . 58
5.1.7 Solution . 59
5.2 Key Issue#2: User Experience . 59
5.2.1 Description . 59
5.2.2 Recommended requirements . 59
5.2.3 GAP Analysis and Evaluation . 59
5.2.3.1 Longer e2e delay over BC bearer issue . 59
5.2.3.2 Mobility issue . 60
5.2.3.2.1 BC handoff to UC . 60
5.2.3.2.2 UC handoff to BC . 61
5.2.4 Assumptions . 61
5.2.5 Solution . 61
5.2.5.1 Transport delay difference adjustment . 61
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3GPP TR 26.989 version 17.0.0 Release 17 4 ETSI TR 126 989 V17.0.0 (2022-05)
5.2.5.2 RTP payload treatment . 61
5.3 Key Issue#3: MCPTT over MBMS support . 62
5.3.1 Description . 62
5.3.2 Deployment Considerations . 64
5.3.3 Realization (Stage 3) Considerations (On-Network) . 64
5.3.4 Media Handling . 64
5.3.5 QoE for MCPTT over MBMS . 65
5.3.5.1 QoE for both MNO and MCPTT service provider . 65
5.3.6 eNB Scheduling on the MBMS Bearer . 65
5.3.7 Needed information to describe an MCPTT User Plane . 65
6 Conclusion . 65
Annex A:  Simulation Models and Parameters . 67
A.1 MBMS Bearer Simulation Model . 67
A.1.1 Coverage. 67
A.1.2 Error Traces . 68
A.1.3 eNB Scheduling . 71
A.2 Correlation between Subjective MOS and P.OLQA . 72
Annex B: Change history . 73
History . 74

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3GPP TR 26.989 version 17.0.0 Release 17 5 ETSI TR 126 989 V17.0.0 (2022-05)
Foreword
rd
This Technical Report has been produced by the 3 Generation Partnership Project (3GPP).
The contents of the present document are subject to continuing work within the TSG and may change following formal
TSG approval. Should the TSG modify the contents of the present document, it will be re-released by the TSG with an
identifying change of release date and an increase in version number as follows:
Version x.y.z
where:
x the first digit:
1 presented to TSG for information;
2 presented to TSG for approval;
3 or greater indicates TSG approved document under change control.
y the second digit is incremented for all changes of substance, i.e. technical enhancements, corrections,
updates, etc.
z the third digit is incremented when editorial only changes have been incorporated in the document.
ETSI

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3GPP TR 26.989 version 17.0.0 Release 17 6 ETSI TR 126 989 V17.0.0 (2022-05)
1 Scope
The present document covers the enhancement required to support MCPTT.
2 References
The following documents contain provisions which, through reference in this text, constitute provisions of the present
document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or
non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including
a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same
Release as the present document.
[1] 3GPP TR 21.905: "Vocabulary for 3GPP Specifications".
[2] 3GPP TS 22.179: "Mission Critical Push To Talk (MCPTT) over LTE; Stage 1"
[3] 3GPP TR 26.952: "Codec for Enhanced Voice Services (EVS);Performance Characterization".
[4] 3GPP TS 26.114: "IP Multimedia Subsystem (IMS); Multimedia Telephony; Media handling and
interaction".
[5] ITU-T Technical Paper - GSTP-GVBR, Performance of ITU-T G.718 (http://www.itu.int/pub/T-
TUT) (http://www.itu.int/pub/publications.aspx-lang=en&parent=T-TUT-ASC-2010).
[6] ETSI EN 300 395-2: "Terrestrial Trunked Radio (TETRA) Speech codec for full-rate traffic
channel Part 2: TETRA codec", version 1.3.1 (25 January 2005).
[7] 3GPP TR 26 975: "Performance characterization of the Adaptive Multi-Rate (AMR) speech
codec".
[8] 3GPP TR 46.055: "Performance characterization of the GSM Enhanced Full Rate (EFR) speech
codec".
[9] (void)
[10] IETF RFC 3550: "RTP: A Transport Protocol for Real-Time Applications".
[11] 3GPP TS 26.346: "Multimedia Broadcast/Multicast Service (MBMS); Protocols and codecs".
[12] 3GPP TS 23.468: "Group Communication System Enablers for LTE (GCSE_LTE); Stage 2".
[13] 3GPP TR 26 976: "Performance characterization of the Adaptive Multi-Rate Wideband (AMR-
WB) speech codec".
[14] 3GPP TS 22.076: "Noise suppression for the AMR codec; Service description; Stage 1".
[15] 3GPP TS 26.131: "Terminal acoustic characteristics for telephony; Requirements".
[16] NTIA Report 15-520: "Speech Codec Intelligibility Testing in Support of Mission-Critical Voice
Applications for LTE", S.D. Voran & A.A. Catellier September 2015.
[17] (void)
[18] (void)
[19] 3GPP TS 36.300: "Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal
Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2".
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3GPP TR 26.989 version 17.0.0 Release 17 7 ETSI TR 126 989 V17.0.0 (2022-05)
[20] 3GPP TR 26.947: "Multimedia Broadcast/Multicast Service (MBMS); Selection and
characterisation of application layer Forward Error Correction (FEC)".
[21] (void)
[22] (void)
[23] (void)
[24] ITU-T Recommendation P.800 (08/1996): "Methods for subjective determination of transmission
quality".
[25] 3GPP TS 26.442: "Codec for Enhanced Voice Services (EVS); ANSI C code (fixed-point)".
[26] 3GPP TS 26.448: "Codec for Enhanced Voice Services (EVS); Jitter buffer management".
[27] ITU-T Recommendation P.807 (02/2016): "Subjective test methodology for assessing speech
intelligibility".
3 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].
ADP Associated Delivery Procedures
AS Application Server
BC Broadcast
BM-SC Broadcast-Multicast - Service Centre
GCS Group Communication Service
MCPTT Mission Critical Push-To-Talk
MBMS Multimedia Broadcast/Multicast Service
MBSFN Multimedia Broadcast Single Frequency Network
MOS Mean Opinion Score
NTIA National Telecommunications & Information Administration
TETRA TErrestrial Trunked Radio
SC-PTM Single Cell-Point To Multipoint
SWB Super Wide Band
UC Unicast
4 Reference Model
Figure 1 shows a reference model of MCPTT support over UC and BC. The GCS AS interacts with UE over GC1
interface for application signalling. The GCS AS determines whether to deliver the audio over UC or BC. GCS AS
interacts with BM-SC over MB2 interface to deliver audio to BM-SC. The BM-SC delivers the audio over broadcast
channel to the UE via SGi-mb interface. The GCS AS interacts with P-GW over SGi interface to deliver audio to the
UE. The red line represents the audio delivered over UC channel. The green line represents the audio delivered over
BC channel.
NOTE: The UE interacts with the BM-SC using HTTP method via SGi interface for MBMS Associated Delivery
Procedure. Whether the ADP procedure applies to the MCPTT is TBD.
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MB2-U
MB2-C
3GPP TR 26.989 version 17.0.0 Release 17 8 ETSI TR 126 989 V17.0.0 (2022-05)
GCS AS
GC1
Gx Rx
PCRF
S/P-
SGi
GW
UE eNB
MBMS
SGi-mb
-GW BM-SC
SGmb

Figure 1: MCPTT support Reference Model
5 Key Issues for Supporting MCPTT
5.1 Key Issue#1: Codec for MCPTT
5.1.1 Review of Codec Alternatives and their Relative Perceptual
Performance
5.1.1.1 Overview of the 3GPP Codec Comparison
The EVS Selection and Characterization Phase Test Results provided in the main body and Annex D of TR 26.952 [3]
give a detailed assessment of the performance of the EVS Codec in realistic scenarios compared to both AMR and
AMR-WB. A summary of this comparison is provided in the next two subclauses.
In the fourth subclause the relative performance of different audio bandwidths coded with AMR, AMR-WB and EVS is
provided showing that the SWB modes of EVS outperform the WB and NB Primary modes of EVS, AMR-WB and
AMR.
In the fifth subclause, a review of the TETRA codec performance in comparison to the 3GPP Codecs is provided.
This version of the document includes a review of codec alternatives and their relative intelligibility in high noise
conditions, e.g., at SNRs in the range of -30 dB to 5 dB. The NTIA report [16] covered six noise types for an
intelligibility study that included a range of public safety and civilian environments. Results of intelligibility testing for
additional public safety specific high noise background conditions are not included in this document.
5.1.1.2 Narrowband Comparison vs AMR
For Narrowband (NB) signals, four experiments were conducted in the EVS Selection and four in the EVS
Characterization. Taken together, these results provide a complete picture of the performance of EVS with respect to
AMR but the highlights are provided in Figures 2 to 6 below.
It can be seen that EVS always significantly out-performs AMR in terms of intrinsic audio quality for both speech and
Mixed/Music signals. EVS is also significantly more robust to frame erasures; both randomly distributed or according
to the Delay and Error profiles from TS 26.114 [4] using the EVS JBM.
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3GPP TR 26.989 version 17.0.0 Release 17 9 ETSI TR 126 989 V17.0.0 (2022-05)


(a) (b)

(c) (d)
Figure 2: EVS NB vs AMR – Speech - Random Frame Erasures - Selection
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3GPP TR 26.989 version 17.0.0 Release 17 10 ETSI TR 126 989 V17.0.0 (2022-05)


(a) (b)

(c) (d)
Figure 3: EVS NB vs AMR – Speech - Random Frame Erasures - Characterization

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3GPP TR 26.989 version 17.0.0 Release 17 11 ETSI TR 126 989 V17.0.0 (2022-05)


(a) (b)
Figure 4: EVS NB vs AMR – Speech - TS 26.114 Delay & Error Profiles


(a) (b)
Figure 5: EVS NB vs AMR – Music & Mixed Content - Random Frame Erasures

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3GPP TR 26.989 version 17.0.0 Release 17 12 ETSI TR 126 989 V17.0.0 (2022-05)


(a) (b)
Figure 6: EVS NB vs AMR – Music & Mixed Content - TS 26.114 Delay & Error Profiles

5.1.1.3 Wideband Comparison vs AMR-WB
For Wideband (WB) signals, seven experiments were conducted during the EVS Selection and five experiments during
Characterization; focused on determining the performance of the EVS Wideband Primary Modes of operation. Taken
together these experiments provide unique information about the performance of EVS with respect to AMR-WB but the
highlights are provided below in Figures 7 to 10.
As in the case of AMR and NB, it can be seen that EVS always significantly out-performs AMR-WB or AMR-
WB/G.718IO in terms of intrinsic audio quality for both speech and Mixed/Music signals. EVS is also significantly
more robust to input level and frame erasures; both randomly distributed or using the EVS JBM in conjunction with the
packet delay and error profiles taken from either TS 26.114 or the new profiles defined for LTE.
What is less clear from the frame erasure plots is that AMR-WB, in its basic form, performs significantly less well than
these curves would suggest. Work in ITU-T as part of the G.718 exercise led to significant improvements to the packet
loss concealment of AMR-WB (G.722.2) and these improvements are shown in Figures 11 & 12 (FER and BFER);
taken from the Characterization Report of Recommendation ITU-T G.718 [5]. The enhancements achieved during the
development of G.718 formed part of the justification of the EVS work item and thus it can be assumed that EVS will
perform even better than suggested by Figures 8, 9 and 10.
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3GPP TR 26.989 version 17.0.0 Release 17 13 ETSI TR 126 989 V17.0.0 (2022-05)


(a) (b)
Figure 7: EVS WB vs AMR-WB – Speech – Clean Channel & Levels



(a) (b)
Figure 8: EVS WB vs AMR-WB – Speech - Random Frame Erasures

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3GPP TR 26.989 version 17.0.0 Release 17 14 ETSI TR 126 989 V17.0.0 (2022-05)



(a) (b)
Figure 9: EVS WB vs AMR-WB – Speech - TS 26.114 Delay & Error Profiles




(a) (b)
Figure 10: EVS WB vs AMR-WB – Speech – New EVS JBM Delay & Error Profiles

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3GPP TR 26.989 version 17.0.0 Release 17 15 ETSI TR 126 989 V17.0.0 (2022-05)



Figure 11: AMR-WB (G.722.2) vs G.718IO – Speech (American English) Figure 27 of [3]
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3GPP TR 26.989 version 17.0.0 Release 17 16 ETSI TR 126 989 V17.0.0 (2022-05)



Figure 12: AMR-WB (G.722.2) vs G.718IO – Speech (French) Figure 28 of [3]
5.1.1.4 Super-wideband EVS and Relationships to Other Bandwidths
Three mixed bandwidth tests were performed during the EVS Characterization and the results are shown in Figure 13.
It is clear from Figure 13 that the Super-wideband (SWB) modes of EVS outperform the WB modes, which themselves
outperform the NB modes. On the whole it is clear that these trends hold across input types and bit rates. The EVS
codec can also be seen to scale well with bit rate within each bandwidth and asymptotically approaches the Direct
Source (DS) in the case of SWB and progressively lower value in the cases of the reduced bandwidth signals; WB and
NB.
The
...