ETSI TR 126 919 V17.0.0 (2022-05)

5G; Study on media handling aspects of conversational services in 5G systems (3GPP TR 26.919 version 17.0.0 Release 17)

RTR/TSGS-0426919vh00

General Information

• Status: Not Published
• Technical Committee: 3GPP SA 4 - Codec
• Current Stage: 12 - Completion
• Completion Date: 05-May-2022

Standards Content (Sample)

TECHNICAL REPORT
5G;
Study on media handling aspects of
conversational services in 5G systems
(3GPP TR 26.919 version 17.0.0 Release 17)

3GPP TR 26.919 version 17.0.0 Release 17 1 ETSI TR 126 919 V17.0.0 (2022-05)

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RTR/TSGS-0426919vh00
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3GPP TR 26.919 version 17.0.0 Release 17 2 ETSI TR 126 919 V17.0.0 (2022-05)
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Contents
Intellectual Property Rights . 2
Legal Notice . 2
Modal verbs terminology . 2
Foreword . 5
Introduction . 5
1 Scope . 6
2 References . 6
3 Definitions and Abbreviations . 7
3.1 Definitions . 7
3.2 Abbreviations . 8
4 5G System Overview. 8
4.1 Introduction . 8
4.2 Stage-1 Requirements . 8
4.3 Stage-2 System Architecture . 9
5 Impacts of 5G Stage-1 Requirements on 3GPP Conversational Services . 11
5.1 Technical Aspect 1: Efficient Speech User Plane . 11
5.1.1 Description . 11
5.1.2 Implications on MTSI . 11
5.1.3 Implications on IMS-based Telepresence . 11
5.1.4 Recommended Requirements . 11
5.1.5 Gap Analysis . 11
5.1.6 Potential Solutions . 12
5.2 Technical Aspect 2: Efficient Video User Plane . 12
5.2.1 Description . 12
5.2.2 Implications on MTSI . 12
5.2.3 Implications on IMS-based Telepresence . 12
5.2.4 Recommended Requirements . 12
5.2.5 Gap Analysis . 12
5.2.6 Potential Solutions . 12
5.3 Technical Aspect 3: Media Rate Adaptation . 12
5.3.1 Description . 12
5.3.2 Implications on MTSI and IMS-based Telepresence . 13
5.3.3 Recommended Requirements . 13
5.3.4 Gap Analysis . 13
5.3.5 Potential Solutions . 13
5.4 Technical Aspect 4: VR Services . 14
5.4.1 Description . 14
5.4.2 Implications on MTSI . 14
5.4.3 Implications on IMS-based Telepresence . 14
5.4.4 Recommended Requirements . 14
5.4.5 Gap Analysis . 14
5.4.6 Potential Solutions . 14
5.5 Technical Aspect 5: 5G New Radio (NR) Access . 16
5.5.1 Description . 16
5.5.2 Implications on MTSI . 16
5.5.3 Implications on IMS-based Telepresence . 17
5.5.4 Recommended Requirements . 17
5.5.5 Gap Analysis . 17
5.5.5.1 Overview of Gaps in MTSI . 17
5.5.5.2 Setting MBR>GBR in 5GS . 17
5.5.5.3 UE Adaptation at Rates > GBR . 18
5.5.6 Potential Solutions . 19
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5.5.6.1 SDP Parameter for End-to-end RAN-assisted codec adaptation support . 19
5.5.6.2 SDP Parameter for link-by-link RAN-assisted codec adaptation support . 20
5.5.6.3 Support of RAN-Assisted Codec Adaptation on NR . 20
5.6 Technical Aspect 6: Profiles for 5G Deployments . 20
5.6.1 Description . 20
5.6.2 Implications on MTSI . 21
5.6.3 Implications on IMS-based Telepresence . 21
5.6.4 Recommended Requirements . 21
5.6.5 Gap Analysis . 21
5.6.6 Potential Solutions . 21
5.7 Technical Aspect 7: Support for Real-Time Interaction . 21
5.7.1 Description . 21
5.7.2 Implications on MTSI . 22
5.7.3 Implications on IMS-based Telepresence . 22
5.7.4 Recommended Requirements . 22
5.7.5 Gap Analysis . 23
5.7.6 Potential Solutions . 23
5.7.6.1 WebRTC Data Channel Framework . 23
5.7.6.1.1 Flexibility in Usage . 23
5.7.6.1.2 Flexibility in Development . 23
5.7.6.1.3 Flexibility in Operations . 24
5.7.6.1.4 Relation to Existing WebRTC in IMS Specifications . 24
5.7.6.2 MSRP . 24
6 Impacts of 5G Stage-2 System Architecture on 3GPP Conversational Services . 25
6.1 Technical Aspect 1: Mapping of Conversational Services to 5G System . 25
6.1.1 Description . 25
6.1.2 Implications on MTSI and IMS-based Telepresence . 25
7 Codecs for 5G Conversational Services . 25
7.1 Introduction . 25
8 QoS Handling for 5G Conversational Services . 25
8.1 Introduction . 25
9 Conclusions . 26
Annex B: Change history . 27
History . 28

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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.
Introduction
The present document studies media handling aspects of 5G conversational services, focusing on Multimedia
Telephony Service over IMS (MTSI) in TS 26.114 [4] and IMS-based Telepresence Service in TS 26.223 [5]. Various
technical aspects including speech codes, video codecs, media rate adaptation, virtual reality (VR) support and new
radio (NR) considerations are addressed, and related gap analysis and potential solutions are documented.
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1 Scope
The present document provides a study on the media handling aspects of conversational services in 5G, taking as
baseline the Stage-1 requirements developed in TS 22.261 [2], as well as the Stage-2 architecture for 5G systems
developed in TS 23.501 [3]. This includes the investigation of the following areas:
- Media handling aspects of the 5G system architecture in relation to 3GPP conversational services, e.g.,
Multimedia Telephony Service over IMS (MTSI) in TS 26.114 [4] and IMS-based Telepresence Service in TS
26.223 [5].
- Relevance and potential reuse of components in existing 3GPP conversational services (e.g., MTSI, IMS-based
telepresence, etc.) in the context of 5G systems and related Stage-2 architecture, e.g., use of MTSI features for
supporting voice and video calls, use of MTSI, MS-MTSI and IMS-telepresence features for supporting multi-
party conferencing, and applicability of existing QoE monitoring and QoS handling mechanisms.
- Potential enhancements to existing 3GPP conversational services (e.g., MTSI, IMS-based telepresence, etc.)
towards better fulfilling the Stage-1 requirements in TS 22.261, e.g., in terms of criteria such as latency and
bandwidth efficiency, while also taking into consideration the Stage-2 architecture for 5G systems:
- In case existing codecs are unable to address 5G application requirements, new media codec requirements for
3GPP conversational services may be developed.
- The need for, and potential use of, new QoS media handling mechanisms in 5G systems such as traffic
classification and codec-aware network elements in the context of 3GPP conversational services.
The gap analysis of the above areas and associated recommendations and conclusions for the proposed improvements
are documented in the present document.
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 22.261: "Service Requirements for Next Generation New Services and Markets;
Stage 1".
[3] 3GPP TS 23.501: "System Architecture for the 5G System; Stage 2".
[4] 3GPP TS 26.114: "IP Multimedia Subsystem (IMS); Multimedia telephony; Media handling and
interaction".
[5] 3GPP TS 26.223: "Telepresence using the IP Multimedia Subsystem (IMS); Media handling and
interaction".
[6] 3GPP TR 23.799: "Study on Architecture for Next Generation System".
[7] 3GPP TS 23.228: "IP Multimedia Subsystem (IMS); Stage 2".
[8] 3GPP TS 23.503: "Policy and Charging Control Framework for the 5G System".
[9] 3GPP TR 26.918: "Virtual Reality (VR) media services over 3GPP".
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[10] 3GPP TS 38.300: "NR; NR and NG-RAN Overall Description".
[11] 3GPP TS 38.331: "NR; Radio Resource Control (RRC); Protocol Specification".
[12] 3GPP TS 36.331: "Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource
Control (RRC) protocol specification".
[13] 3GPP TR 26.910: "Study on Media Handling Aspects of RAN Delay Budget Reporting in MTSI".
[14] 3GPP TR 26.959: "Study on enhanced Voice over LTE (VoLTE) performance".
[15] ISO/IEC 23008-2: "Information technology -- High efficiency coding and media delivery in
heterogeneous environments -- Part 2: High efficiency video coding".
[16] ISO/IEC 23090-2: " Information technology -- Coded representation of immersive media -- Part 2:
Omnidirectional media format".
[17] 3GPP TS 26.118: "3GPP Virtual reality profiles for streaming applications".
[18] IETF RFC 7798 (2016): "RTP Payload Format for High Efficiency Video Coding (HEVC)", Y.-K.
Wang, Y. Sanchez, T. Schierl, S. Wenger, M. M. Hannuksela.
[19] 3GPP TS 26.238: "Uplink Streaming".
[20] 3GPP TS 38.306: "NR; User Equipment (UE) radio access capabilities".
[21] 3GPP TS 38.321: "NR; Medium Access Control (MAC) protocol specification".
[22] 3GPP TS 38.300: "NR; NR and NG-RAN Overall Description; Stage 2".
[23] WebRTC 1.0: "Real-time Communication Between Browsers", W3C Candidate Recommendation,
27 September 2018, https://www.w3.org/TR/2018/CR-webrtc-20180927/
[24] IETF Internet Draft draft-ietf-rtcweb-data-channel-13 (2015): "WebRTC Data Channel",
https://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-13, WORK IN PROGRESS.
[25] IETF RFC 4566 (2006), "SDP: Session Description Protocol".
[26] IETF Internet Draft draft-ietf-mmusic-data-channel-sdpneg-28 (2019): "SDP-based Data Channel
Negotiation", https://tools.ietf.org/html/draft-ietf-mmusic-data-channel-sdpneg-28, WORK
IN PROGRESS.
[27] Node.js, Node.js Foundation, https://nodejs.org/
[28] IETF RFC 4975 (2007), "The Message Session Relay Protocol (MRSP) "
[29] 3GPP TS 24.247: "Messaging service using the IP Multimedia (IM) Core Network (CN)
subsystem".
[30] IETF Internet Draft draft-ietf-mmusic-msrp-usage-data-channel-12 (2019), "MSRP over Data
Channels", https://tools.ietf.org/html/ draft-ietf-mmusic-msrp-usage-data-channel-12, WORK IN
PROGRESS.
[31] 3GPP TS 24.371: "WebRTC access to the IMS; Stage 3; Protocol specification".
3 Definitions and Abbreviations
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].
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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].
5GC 5G Core
AF Application Function
AMF Access and Mobility Management Function
AN Access Network
ANBR Access Network Bitrate Recommendation
AS Application Server
CMR Codec Mode Request
CN Core Network
CP Control Plane
ECN Explicit Congestion Notification
IBCF Interconnection Border Control Function
KPI Key Performance Indicator
MRFC Media Resource Function Controller
MRFP Media Resource Function Processor
MTSI Multimedia Telephony Service over IMS
MS-MTSI Multi-Stream MTSI
NEF Network Exposure Function
NR New Radio
NRF Network Repository Function
OMAF Omnidirectional MediA Format
PCF Policy Control Function
QoE Quality of Experience
SA Standalone
SEI Supplemental Enhancement Information
SMF Session Management Function
SRVCC Single Radio Voice Call Continuity
TMMBN Temporary Maximum Media Stream Bit Rate Notification
TMMBR Temporary Maximum Media Stream Bit Rate Request
TrGW Transition Gateway
UDM Unified Data Management
UDR Unified Data Repository
UL Up-link
UP User Plane
UPF User Plane Function
VoLTE Voice over LTE
VoNR Voice over NR
4 5G System Overview
4.1 Introduction
This clause provides the background on 5G system requirements and architecture. Clause 4.2 describes the 5G Stage-1
Requirements. Clause 4.3 describes 5G Stage-2 architecture.
4.2 Stage-1 Requirements
TS 22.261 [2] developed by SA1 compiles service and operational requirements that define a 5G system. The 5G
system is characterised, for example, by:
- Support for multiple access technologies
- Scalable and customizable network
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- Advanced Key Performance Indicators (KPIs) (e.g., availability, latency, reliability, user experienced data rates,
area traffic capacity)
- Flexibility and programmability (e.g., network slicing, diverse mobility management, Network Function
Virtualization)
- Resource efficiency (both user plane and control plane)
- Seamless mobility in densely populated and heterogeneous environment
- Extreme long range coverage in low density areas
- Markets requiring minimal service levels with minimal user experience requirements around performance
metrics such as bitrate, latency and coverage
- Support for real time and non-real time multimedia services and applications with advanced Quality of
Experience (QoE), including services such as telepresence, virtual presence and telemedicine support
Many of the considered 5G system-related use cases and associated requirements in TS 22.261 relate to multimedia
delivery, processing and storage.
4.3 Stage-2 System Architecture
In order to address the Stage-2 architectural aspects of 5G systems, SA2 has completed normative work "5G System -
Phase 1", defined to support data connectivity and services enabling deployments to use techniques such as e.g.
Network Function Virtualization and Software Defined Networking. For this purpose, the specification TS 23.501 [3]
was developed, based on the conclusions of the Rel-14 study item FS_NextGen and related TR 23.799 [6].
TS 23.501 covers the 5G System architecture that is defined to support data connectivity and services enabling
deployments to use techniques such as Network Function Virtualization and Software Defined Networking. The 5G
System architecture leverages service-based interactions between Control Plane (CP) Network Functions where
identified. Some key principles and concept are to:
- Separate the User Plane (UP) functions from the Control Plane (CP) functions, allowing independent scalability,
evolution and flexible deployments, e.g. at a centralized location or distributed (remote) locations.
- Modularize the function design, e.g. to enable flexible and efficient network slicing.
- Wherever applicable, define procedures (i.e. the set of interactions between network functions) as services, so
that their re-use is possible.
- Enable each Network Function to interact with other NF directly if required. The architecture does not preclude
the use of an intermediate function to help route Control Plane messages (e.g. like a DRA).
- Minimize dependencies between the Access Network (AN) and the Core Network (CN). The architecture is
defined with a converged core network with a common AN - CN interface which integrates different 3GPP and
non-3GPP access types.
- Support a unified authentication framework.
- Support "stateless" NFs, where the "compute" resource is decoupled from the "storage" resource.
- Support capability exposure.
- Support concurrent access to local and centralized services. To support low latency services and access to local
data networks, UP functions can be deployed close to the Access Network.
- Support roaming with both Home routed traffic as well as Local breakout traffic in the visited PLMN.
The 5G architecture is defined as service-based and the interaction between network functions is represented in two
ways.
- A service-based representation, where network functions (e.g. AMF) within the Control Plane enables other
authorized network functions to access their services. This representation also includes point-to-point reference
points where necessary.
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- A reference point representation, which shows the interaction between the NF services in the network functions
described by point-to-point reference point (e.g. N11) between any two network functions (e.g. AMF and SMF).
Figure 4.3.1 depicts the non-roaming reference architecture. Service-based interfaces are used within the Control Plane.
AF
NSSF NEF NRF PCF UDM
Npcf Nudm
Nnrf
Nnef
Nnssf Naf
Nausf
Namf Nsmf
AUSF SMF
AMF
N4
N2
N3
UE (R)AN UPF N6 DN
Figure 4.3.1: 5G System architecture
Figure 4.3.2 depicts the 5G System architecture in the non-roaming case, using the reference point representation
showing how various network functions interact with each other.
AUSF N13 UDM
NSSF
N22 N12 N8 N10
AMF N11 SMF N7 PCF N5 AF
N14 N15
N1 N2 N4
UE (R)AN N3 UPF N6
DN
N9
Figure 4.3.2: Non-Roaming 5G System Architecture in reference point representation
The 5G System architecture consists of the following network functions (NF):
- Application Function (AF) interacts with the 3GPP Core Network in order to provide services, for example to
support the following functionalities: Application influence on traffic routing, accessing Network Exposure
Function, interacting with the Policy framework for policy control.
- Access and Mobility Management function (AMF) includes the following functionalities: Mobility management,
connection management, lawful intercept, transparent proxy, access authentication and authorization.
- Session Management Function (SMF) includes the following functionalities: Session establishment,
modification and release, selection and control of UP function, UE IP address allocation and management, traffic
steering configuration at UPF, control part of policy enforcement and QoS, charging data collection.
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- User Plane Function (UPF) includes the following functionalities: Packet routing & forwarding, packet
inspection, user plane part of policy rule enforcement, lawful intercept (UP collection), traffic usage reporting,
external PDU session point of interconnect to data network.
- Policy Control Function (PCF) includes the following functionalities: Providing policy rules to control plane
functions to enforce them, serving as a front end to access subscription information relevant for policy decisions.
- Network Exposure Function (NEF) includes the following functionality: Providing means to securely expose the
services and capabilities of the 3GPP network to third parties, including application functions and edge
computing.
- Network Repository Function (NRF) includes the following functionalities: Support of service discovery,
maintaining NF profile of available NF instances and providing information of the discovered NF instances.
- Unified Data Management (UDM) includes the following functionalities: 3GPP AKA Authentication Credential
Processing, User Identification Handling, Access Authorization, Registration/Mobility management,
Subscription management, SMS management.
- Unified Data Repository (UDR) includes the following functionalities: Storage and retrieval of subscription data
by the UDM, storage and retrieval of policy data by the PCF, storage and retrieval of application data (including
packet flow descriptions) by the NEF.
5 Impacts of 5G Stage-1 Requirements on 3GPP
Conversational Services
5.1 Technical Aspect 1: Efficient Speech User Plane
5.1.1 Description
Clause 6.1 of TS 22.261 [2] requires an efficient 5G user plane. While the requirement text focuses on efficient user
plane routing, user plane "efficiency" in the sense of achieved media quality per transmitted bit should also be in scope.
5.1.2 Implications on MTSI
Current MTSI speech does not mandate use of the most bit-efficient and highest quality speech, but leaves it optional.
To better meet 5G requirements, the most bit-efficient, highest quality speech should be made mandatory.
5.1.3 Implications on IMS-based Telepresence
Current IMS-based Telepresence already mandates use of the most bit-efficient and highest quality speech, so there is
no foreseen impact from this aspect.
5.1.4 Recommended Requirements
It is recommended that 5G MTSI UE support for AMR and AMR-WB codecs is mandated, so as to minimize
transcoding needs.
It is also recommended that the level of support for EVS and SWB operation be developed.
5.1.5 Gap Analysis
In current MTSI, super-wideband speech support is optional, and the most bit-efficient wideband and narrowband
codecs are optional.
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5.1.6 Potential Solutions
A solution is to mandate for MTSI clients in terminals offering speech communication to support narrowband,
wideband and super-wideband communication.
5.2 Technical Aspect 2: Efficient Video User Plane
5.2.1 Description
Clause 6.1 of TS 22.261 [2] requires an efficient 5G user plane. While the requirement text focuses on efficient user
plane routing, user plane "efficiency" in the sense of achieved media quality per transmitted bit should also be in scope.
5.2.2 Implications on MTSI
Currently, it is not mandated for video-capable MTSI endpoints to use the most bit-efficient and highest quality video,
but it is left as optional. To better meet 5G requirements, it should be mandatory for video-capable 5G MTSI endpoints
to use the most bit-efficient, highest quality video.
5.2.3 Implications on IMS-based Telepresence
Currently, it is not mandated for video-capable IMS-based Telepresence endpoints to use the most bit-efficient and
highest quality video, but it is left as optional. To better meet 5G requirements, it should be mandatory for video-
capable 5G IMS-based Telepresence endpoints to use the most bit-efficient, highest quality video.
5.2.4 Recommended Requirements
It is recommended that support for H.265/HEVC (with the levels and profiles currently recommended respectively in
TS 26.114 and TS 26.223) is mandated for video-capable 5G MTSI and IMS Telepresence clients in terminals.
In addition, it is recommended that 5G MTSI UEs support H.264 (AVC) constrained baseline profile level 1.2, and that
5G IMS Telepresence UEs support H.264 (AVC) constrained high profile level 3.1 and H.264 (AVC) constrained
baseline profile level 1.2, as currently specified in TS 26.114 and TS 26.223, as to minimize transcoding needs.
5.2.5 Gap Analysis
Currently, H.265/HEVC support is optional for MTSI and IMS Telepresence endpoints.
5.2.6 Potential Solutions
A solution to achieve support for the most bitrate-efficient and highest quality video in 5G MTSI, is to mandate support
in video-capable endpoints for the, currently optional, H.265/HEVC Main Profile, Main Tier, Level 3.1.
A solution to achieve support for the most bitrate-efficient and highest quality video in 5G Telepresence, is to mandate
support in video-capable endpoints for the, currently optional, H.265/HEVC Main Profile, Main Tier, Level 4.1.
5.3 Technical Aspect 3: Media Rate Adaptation
5.3.1 Description
Clause 6.16 of TS 22.261 [2] requires handling markets requiring minimal service levels. Interoperability between such
markets and other markets without such minimal service levels would be improved if the higher service level markets
are capable to automatically adapt to the lower service level.
Clause 6.17 of TS 22.261 [2] requires handling extreme long range coverage in low density areas. It can be assumed
that extreme long range coverage would also mean use of very low media bitrates, as well as dynamically removing or
adding entire media components, when passing some minimum bitrate threshold for inclusion of that media component
ETSI
3GPP TR 26.919 version 17.0.0 Release 17 13 ETSI TR 126 919 V17.0.0 (2022-05)
in the session. Transcoding-free interoperability between UE camping in low density area and UE in other areas without
such major bitrate limits would be improved if UE without bitrate limitations are capable to automatically and
dynamically adapt to the UE having such limitation.
Clause 7.1 of TS 22.261 [2] requires handling high data rates and traffic densities. Seen from a media perspective for an
individual UE, handling high data rates allows using high media bitrates. On the other hand, handling high traffic
densities can mean that the same, individual UE gets allotted a fairly low media bitrate. Since traffic density as well as
general radio conditions can be expected to vary over time, the available media bitrate can in general also be expected
to vary over time, even during a single call. Meeting those requirements will be easier if the UE has the capability to
automatically and dynamically adapt its sending bitrate to match available bitrate on the local uplink, and assist the
remote media sender to match available bitrate on the local downlink. End-to-end transcoding-free operation is enabled
by dynamically adapting sending bitrate to the minimum of the total end-to-end media path, including local uplink and
remote downlink.
Clause 7.2 of TS 22.261 [2] requires handling low latency and high reliability. Seen from a media perspective for an
individual UE, a key part of keeping low media latency and high reliability is to, at any point in time, avoid sending
higher media bitrate than what the end-to-end media path can currently support. Such media bitrate is assumedly always
lower than the maximum allowed, negotiated bandwidth, but there can also be more dynamically varying limitations
that are lower than that negotiated upper limit, e.g. caused by other network traffic and/or various types of physical
limitations in the end-to-end media path. Sending a higher bitrate that what the end-to-end media path can transport, can
either cause data buffering, which increases media latency, or if buffering capabilities are limited, instead decrease
reliability by causing excess media data loss/discard. Meeting those requirements will be easier if the UE has the
capability to automatically and dynamically adapt its sending bitrate to match available bitrate on the end-to-end media
path.
5.3.2 Implications on MTSI and IMS-based Telepresence
Current MTSI and IMS-based Telepresence does not mandate support and use of all bitrate adaptation functionality
included in the respective specification, but leaves some parts of it optional. To better meet 5G requirements, the best
possible bitrate adaptation using available methods should be made mandatory.
5.3.3 Recommended Requirements
It is recommended that best possible bitrate adaptation using available methods is made mandatory for 5G MTSI and
IMS Telepresence.
5.3.4 Gap Analysis
In current MTSI and IMS Telepresence, use of a=bw-info, ANBR, ECN, sending CMR, and video triggers capable to
detect 10% or more reduction in video bitrate are optional.
5.3.5 Potential Solutions
A tentative solution to enhance the bitrate adaptation with available methods in 5G MTSI and IMS Telepresence is to
recommend the support for the following capabilities for MTSI and TP clients:
- If so configured by the operator, support of ANBR as an adaptation trigger, as described by clause 10.7 of TS
26.114 [2].
- If so configured by the operator, speech media receiver capability to trigger
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