Content for TR 26.822 Word version: 19.0.0

3.1 Terms 3.2 Symbols 3.3 Abbreviations
...

1 Scope p. 9

The Technical Report focuses on optimizing the use of RTP for the transport of real-time XR media (including conversational media) and associated metadata. The use of the IMS Data Channel is supported by existing services such as MTSI but is outside the scope of this report. Aspects related to QUIC are outside the scope of this report.

2 References p. 9

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]

TR 21.905: "Vocabulary for 3GPP Specifications".

[2]

TS 26.522: "5G Real-time Media Transport Protocol Configurations".

[3]

TS 23.501: "System architecture for the 5G System (5GS)".

[4]

RFC 8872: "Guidelines for Using the Multiplexing Features of RTP to Support Multiple Media Streams".

[5]

RFC 5761: "Multiplexing RTP Data and Control Packets on a Single Port".

[6]

TR 23.700-70: "Study on architecture enhancement for Extended Reality and Media service (XRM); Phase 2".

[7]

RFC 8285 (2017): "A General Mechanism for RTP Header Extensions", D. Singer, H. Desineni, R. Even.

[8]

RFC 3711: "The Secure Real-time Transport Protocol (SRTP)".

[9]

RFC 9335: "Completely Encrypting RTP Header Extensions and Contributing Sources".

[10]

RFC 6904 (2013): "Encryption of Header Extensions in the Secure Real-time Transport Protocol (SRTP)", J. Lennox.

[11]

RFC 8402 (2018): "Segment Routing Architecture".

[12]

RFC 791 (1981): "Internet Protocol".

[13]

RFC 5109: "RTP Payload Format for Generic Forward Error Correction (ULP FEC): Uneven Level Protection, different redundancies for different packets with different importance".

[14]

RFC 8627: "RTP Payload Format for Flexible Forward Error Correction (Flex FEC): flexible FEC".

[15]

RFC 6681: "Raptor Forward Error Correction (FEC) Schemes for FECFRAME: FEC scheme based on the Raptor".

[16]

RFC 6865: "Simple Reed-Solomon Forward Error Correction (FEC) Scheme for FECFRAME: FEC scheme based on Reed-Solomon".

[17]

RFC 5053: "Raptor Forward Error Correction Scheme for Object Delivery".

[18]

RFC 6330: "RaptorQ Forward Error Correction Scheme for Object Delivery".

[19]

RFC 6363: "Forward Error Correction (FEC) Framework".

[20]

RFC 8854: "WebRTC Forward Error Correction Requirements".

[21]

TR 38.340: "Study on User Equipment (UE) power saving in NR".

[22]

RFC 8298: "Self-Clocked Rate Adaptation for Multimedia".

[23]

Enhancing Video Network Resiliency With LTR and RS Code | At Scale Conferences, available online: https://atscaleconference.com/enhancing-video-network-resiliency-with-ltr-and-rs-code/

[24]

P. Aggarwal et al., [2304.03732] Enabling immersive experiences in challenging network conditions (arxiv.org)

[25]

Nvidia GeForce Now, Video FEC for WebRTC presentation 17 Nov. 2022, available online: https://www.youtube.com/watch?v=igm7QkqxHqk&ab_channel=KrankyGeek

[26]

Holmer S., et al., Handling Packet Loss in WebRTC, 2013 IEEE International Conference on Image Processing, available online: https://static.googleusercontent.com/media/research.google.com/en//pubs/archive/41611.pdf.

[27]

A Google Congestion Control Algorithm for Real-Time Communication, draft-ietf-rmcat-gcc-02, 2016.

[28]

WebRTC source code: https://source.chromium.org/chromium/chromium/src/+/main:third_party/webrtc, retrieved May 1, 2024.

[29]

RFC 8698: "Network-Assisted Dynamic Adaptation: A Unified Congestion Control Scheme for Real-Time Media", 2020.

[30]

Self-Clocked Rate Adaptation for Multimedia, draft-johansson-ccwg-rfc8298bis-screamv2-00, 2024.

[31]

RFC 4588: "RTP Retransmission Payload Format".

[32]

TS 26.114: "IP Multimedia Subsystem (IMS); Multimedia telephony; Media handling and interaction".

[33]

RFC 4585: " Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)".

[34]

RFC 8085: "UDP Usage Guidelines".

[35]

RFC 8834: "Media Transport and Use of RTP in WebRTC".

[36]

RFC 2250: "RTP Payload Format for MPEG1/MPEG2 Video".

[37]

RFC 9143: "Negotiating Media Multiplexing Using the Session Description Protocol (SDP)".

[38]

RFC 7941: "RTP Header Extension for the RTP Control Protocol (RTCP) Source Description Items".

[39]

GStreamer: open source multimedia framework: https://gstreamer.freedesktop.org/.

[40]

Wowza Streaming Engine™: https://www.wowza.com/.

[41]

Media MTX: Ready-to-use SRT / WebRTC / RTSP / RTMP / LL-HLS media server and media proxy that allows to read, publish, proxy, record and playback video and audio streams: http://github.com/blueviron/mediamtx.

[42]

Adobe RTMP Specification (veriskope.com): https://rtmp.veriskope.com/docs/spec/.

[43]

RTP Extensions for Transport-wide Congestion Control, draft-holmer-rmcat-transport-wide-cc-extensions-01 https://datatracker.ietf.org/doc/html/draft-holmer-rmcat-transport-wide-cc-extensions-01

[44]

RFC 3550: "RTP: A Transport Protocol for Real-Time Applications".

[45]

RFC 5104: "Codec Control Messages in the RTP Audio-Visual Profile with Feedback (AVPF)".

[46]

RFC 6679: "Explicit Congestion Notification (ECN) for RTP over UDP".

[47]

RFC 8888: "RTP Control Protocol (RTCP) Feedback for Congestion Control".

[48]

RFC 8382: "Shared Bottleneck Detection for Coupled Congestion Control for RTP Media".

[49]

RFC 3611: "RTP Control Protocol Extended Reports (RTCP XR)".

[50]

TS 26.510: "Media delivery; interactions and APIs for provisioning and media session handling".

[51]

Di Domenico, Andrea, et al. "A network analysis on cloud gaming: Stadia, GeForce Now and PS Now." Network 1.3 (2021): 247-260.

[52]

TR 26.928: "Extended Reality (XR) in 5G".

[53]

TS 26.506: "5G Real-time Media Communication Architecture (Stage 2)".

[54]

TS 23.228: "IP Multimedia Subsystem (IMS) - Stage 2".

[55]

TS 29.571: "5G System; common data types for Service based interfaces; stage 3".

[56]

TS 38.415: "NG-RAN; PDU Session User Plane Protocol".

[57]

Real-Time Transport Protocol (RTP) Parameters (iana.org).

[58]

TS 26.113: "Real-Time Media Communication; Protocols and APIs".

[59]

TR 26.922: "Video telephony robustness improvements extensions; Performance evaluation".

[60]

TR 26.926: "Traffic Models and Quality Evaluation Methods for Media and XR Services in 5G Systems".

[61]

TS 38.413: "NG-RAN; NG Application Protocol (NGAP)".

3 Definitions of terms, symbols and abbreviations p. 11

3.1 Terms p. 11

For the purposes of the present document, the terms given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.

Data Burst:

A data burst is a set of multiple PDUs generated and sent by the application such that there is an idle period between two data bursts. A Data Burst can be composed of one or multiple PDU Sets.

Lone PDU:

A PDU that is not marked by the sender as part of a PDU Set.

Multimedia Session:

An association among a group of participants engaged in the communication via one or more RTP sessions, as defined in section 2.2.4 of IETF RFC 7656 [18].

PDU Set marking:

Marking the PDUs carrying a payload with the PDU Set Information.

PDU Set:

One or more PDUs carrying the payload of one unit of information generated at the application level (e.g. frame(s), video slice(s), metadata, etc.).

XR Tethered Device:

Device connected indirectly to 5G Network.

3.2 Symbols p. 12

Void.

3.3 Abbreviations p. 12

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

AL-FEC

Application-Layer Forward Error Correction

AVC

Advanced Video Coding

CDRX

Connected mode discontinuous reception

GCC

Google Congestion Control

H.266/VVC

ITU H.266/MPEG Versatile Video Coding

(RTP) Header Extension

HEVC

High Efficiency Video Coding

IMS

IP Multimedia Subsystem

IRAP

Intra Random Access Picture

MTSI

Multimedia Telephony Service for IMS

NADA

Network-Assisted Dynamic Adaptation

NAL

Network Abstraction Layer

NG-RAN

Next Generation Radio Access Network

NPDS

Number of PDUs in a PDU Set

NTP

Network Time Protocol

Operating System

PCC

Performance-oriented Congestion Control

PSI

PDU Set Importance

PSN

PDU Sequence Number within a PDU Set (PSN)

PSSize

PDU Set Size

PSSN

PDU Set Sequence Number

PTP

Precision Time Protocol

RLC

Radio Link Control

rPSSize

remaining PDU Set Size

RTC

Real Time Communication

RTCP XR

RTCP eXtended Report

RTCP

RTP Control Protocol

SCReAM

Self-Clocked Rate Adaptation for Multimedia

SRTP

Secure RTP

UDP

User Datagram Protocol

UPF

User Plane Function

eXtended Reality