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Content for TR 26.822 Word version: 19.0.0

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4 Architectural Assumptions and Requirements p. 12

4.1 Architectural Assumptions p. 12

4.2 Architectural Requirements p. 14

5 Key Issues p. 14

5.1 Key Issue #1: Inaccuracy of the PDU Set Size (PSSize) information p. 14

5.1.1 Description p. 14

5.2 Key Issue #2: QoS handling requirements for lone PDU p. 14

5.2.1 Description p. 14

5.3 Key Issue #3: Enhancements for application-layer FEC support p. 15

5.3.1 Description p. 15

5.4 Key Issue #4: AL-FEC awareness for PDU Set handling p. 15

5.4.1 Description p. 15

5.5 Key Issue #5: RTP transport of XR metadata p. 16

5.5.1 Description p. 16

5.6 Key Issue #6: PDU Set marking for XR streams with RTP end-to-end encryption p. 16

5.6.1 Description p. 16

5.7 Key Issue #7: Existing RTCP messages and RTP header extensions to better support XR services in 5G p. 17

5.7.1 Description p. 17

5.8 Key Issue #8: RTP retransmission in supporting XR services in 5G p. 17

5.8.1 Description p. 17

5.9 Key Issue #9: Feasibility of RTP multiplexing options for transport of XR media streams p. 18

5.9.1 Description p. 18

5.10 Key Issue #10: Use cases and intended deployment scenarios for enhancements of RTP header extension for PDU Set marking p. 18

5.10.1 Description p. 18

5.11 Key Issue #11: Enhancements of RTP header extension for PDU Set marking p. 19

5.11.1 Description p. 19

5.12 Key Issue #12: Enhancements of Data Burst Marking p. 19

5.12.1 Description p. 19

5.13 Key Issue #13: Applicability of the RTP header extension for PDU Set marking to different PDU Set types p. 19

5.13.1 Description p. 19

5.14 Key Issue #14: Traffic detection and QoS flow mapping for multiplexed media stream data flows p. 20

5.14.1 Description p. 20

5.15 Key Issue #15: Media and metadata delivery over multiple sessions p. 20

5.15.1 Description p. 20

6 Solutions p. 22

6.0 Mapping of Solutions to Key Issues p. 22

6.1 Solution #1: Different PDU Set types to support handling of immersive media p. 22

6.1.1 Key Issue mapping p. 22

6.1.2 Description p. 22

6.2 Solution #2: Gap analysis on the QoS requirements for lone PDUs p. 23

6.2.1 Key Issue mapping p. 23

6.2.2 Description p. 23

6.2.3 Conclusion p. 25

6.3 Solution #3: SRTP Usage for end-to-end encryption p. 26

6.3.1 Key Issue mapping p. 26

6.3.2 Description p. 26

6.4 Solution #4: Measurement Based Pre-compensation for PDU Set Size Correction p. 26

6.4.1 Key Issue mapping p. 26

6.4.2 Description p. 26

6.5 Solution #5: Introduction of AL-FEC schemes defined in IETF p. 32

6.5.1 Key Issue mapping p. 32

6.5.2 Description p. 32

6.5.3 Categorization p. 34

6.6 Solution #6: Time to next burst extension for the RTP HE for PDU Set marking p. 35

6.6.1 Key Issue mapping p. 35

6.6.2 Background p. 35

6.6.3 Description p. 36

6.7 Solution #7: PDU Set Size information correction by indicating the remaining PDU Set Size in RTP header extension p. 36

6.7.1 Key Issue mapping p. 36

6.7.2 Description p. 36

6.8 Solution #8: Definition of the PDU Set for Application-Layer FEC p. 38

6.8.1 Key Issue mapping p. 38

6.8.2 Description p. 38

6.9 Solution #9: RTP retransmission aware PDU Set handling p. 39

6.9.1 Key Issue mapping p. 39

6.9.2 Background p. 39

6.9.2.1 RTP retransmission payload format defined in IETF p. 39

6.9.2.2 WebRTC usage p. 41

6.9.2.3 Feasibility of RTP retransmission in XR applications p. 41

6.9.3 Description p. 42

6.10 Solution #10: AL-FEC awareness at RAN while considering upstream and downstream packet losses p. 43

6.10.1 Key Issue mapping p. 43

6.10.2 Description p. 43

6.10.2.1 Motivation p. 43

6.10.2.2 Solution p. 44

6.11 Solution #11: PSI indication to optimize RTP retransmission p. 46

6.11.1 Key Issue mapping p. 46

6.11.2 Description p. 47

6.12 Solution #12: MID packet filtering p. 48

6.12.1 Key Issue mapping p. 48

6.12.2 Description p. 48

6.13 Solution #13: Dynamic traffic characteristics of RTP sender implementations p. 50

6.13.1 Key Issue mapping p. 50

6.13.2 Description p. 50

6.13.2.1 General p. 50

6.13.2.2 WebRTC and paced sender implementation p. 50

6.13.2.3 GStreamer multimedia framework RTP implementation for P2P p. 53

6.13.2.4 Server-side senders p. 56

6.13.2.5 Aggregate Statistics p. 60

6.13.3 Discussion and conclusion p. 62

6.13.4 Conclusion p. 63

6.14 Solution #14: Candidate RTCP messages and RTP header extensions to support XR services in 5G p. 63

6.14.1 Key Issue mapping p. 63

6.14.2 Description p. 63

6.14.2.1 RTCP messages p. 63

6.14.2.2 RTP header extensions p. 66

6.15 Solution #15: PSI signaling for lone PDUs p. 66

6.15.2 Description p. 66

6.15.2.1 Background p. 66

6.15.2.2 Solution description p. 68

6.15.2.3 Analysis of the solution p. 68

6.16 Solution #16: RTP header extension for dynamic traffic characteristics p. 69

6.16.1 Key Issue mapping p. 69

6.16.2 Description p. 69

6.16.2.1 Intended usage in 5GS p. 70

6.16.2.3 One-byte RTP header extension format p. 70

6.16.2.4 Two-byte RTP Header Extension Format p. 70

6.16.2.5 Semantics p. 71

6.16.2.6 SDP Signaling p. 71

6.16.2.7 Guidelines for dynamic traffic characteristics signaling p. 72

6.16.2.8 Proposed Annex D.3 p. 72

6.16.2.9 Discussion of the solution p. 73

6.17 Solution #17: Analysis of AL-FEC awareness in 3GPP p. 73

6.17.1 Key Issue mapping p. 73

6.17.2 Description p. 73

6.17.2.1 Common attributes of AL-FEC deployments p. 73

6.17.2.2 End-to-end transport perspective p. 74

6.17.2.3 Overhead of AL-FEC p. 76

6.18 Solution #18: Real-time communication congestion control algorithms and AL-FEC p. 79

6.18.1 Key Issue mapping p. 79

6.18.2 Description p. 79

6.18.2.1 General p. 79

6.18.2.2 Google Congestion Control (GCC) p. 79

6.18.2.3 PCC p. 81

6.18.2.4 NADA p. 81

6.18.2.5 SCReAMv2 p. 81

6.18.2.6 Summary of congestion control algorithms p. 82

6.18.2.7 Packet loss rate calculation for AL-FEC p. 82

6.19 Solution #19: Congestion control enhancement to support AL-FEC awareness handling p. 83

6.19.1 Key Issue mapping p. 83

6.19.2 Description p. 83

6.19.2.1 Background of using AL-FEC for real-time communication in cellular networks p. 83

6.19.2.2 Potential Benefits of Application-layer FEC awareness for PDU Set handling p. 84

6.19.2.3 Implications of Application-layer FEC awareness for PDU Set handling on congestion control p. 85

6.19.2.4 The Proposed Solution p. 85

6.20 Solution #20: Guidelines for PDU Set Marking of Unmarked/Lone PDUs p. 86

6.20.1 Key Issue mapping p. 86

6.20.2 Description p. 86

6.20.2.1 General p. 86

6.20.2.2 Guideline for PDU Set marking of lone/unmarked PDUs p. 86

6.20.2.3 Discussion p. 88

6.21 Solution #21: Periodicity and TTNB with the lone PDU p. 88

6.21.1 Key Issue mapping p. 88

6.21.2 Description p. 88

6.21.3 Conclusion p. 89

6.22 Solution #22: Guidelines for PDU Set Marking in Multiplexing Scenarios p. 90

6.22.1 Key Issue mapping p. 90

6.22.2 Description p. 90

6.22.2.1 General p. 90

6.22.2.2 Unmarked packet handling p. 90

6.22.2.3 RTP HE for multiplexed content p. 91

6.22.3 Proposal p. 93

6.23 Solution #23: PDU Set Size and Over Provisioning in RTP HE for PDU Set Marking p. 93

6.23.1 Key Issue mapping p. 93

6.23.2 Description p. 93

6.23.2.1 General p. 93

6.23.2.2 Usage of PDU Set Size in NG-RAN p. 94

6.23.2.3 Discussion p. 95

6.23.3 Proposal p. 95

6.24 Solution #24: Traffic pattern prediction for real-time video communication p. 95

6.24.1 Key issue mapping p. 95

6.24.2 Description p. 95

6.24.2.1 The need for traffic pattern indication p. 95

6.24.2.2 Time to the next data burst (TTNB) p. 96

6.24.2.3 Burst size p. 97

6.25 Solution #25: Definition of the time to the next data burst p. 99

6.25.1 Key Issue mapping p. 99

6.25.2 Possible definitions and a comparison p. 99

6.26 Solution #26: RTP HE Enhancements for Data Boosting Indication p. 100

6.26.1 Key Issue mapping p. 100

6.26.2 Description p. 100

6.26.3 Conclusion p. 101

6.27 Solution #27: Conveying AL-FEC information to the network p. 101

6.27.1 Key Issue mapping p. 101

6.27.2 Description p. 101

6.28 Solution #28: Control-Plane Solution to the Key Issue on Enhancements of Data Burst Marking p. 102

6.28.1 Key Issue mapping p. 102

6.28.2 Description p. 102

6.28.3 Proposed solution p. 105

7 Conclusions p. 105

7.1 Key issues progress p. 105

7.2 Conclusions for Key Issue #1 p. 106

7.3 Conclusions for Key Issue #2 p. 107

7.4 Conclusions for Key Issue #3 p. 107

7.5 Conclusions for Key Issue #4 p. 107

7.6 Conclusions for Key Issue #5 p. 107

7.7 Conclusions for Key Issue #6 p. 108

7.8 Conclusions for Key Issue #7 p. 108

7.9 Conclusions for Key Issue #8 p. 108

7.10 Conclusions for Key Issue #9 p. 108

7.11 Conclusions for Key Issue #10 p. 108

7.12 Conclusions for Key Issue #11 p. 108

7.13 Conclusions for Key Issue #12 p. 108

7.14 Conclusions for Key Issue #13 p. 109

7.15 Conclusions for Key Issue #14 p. 109

7.16 Conclusions for Key Issue #15 p. 109

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