Content for TR 26.924 Word version: 18.0.0
2 References
3 Definitions and abbreviations
4 Overview
5 Current QoS reservation mechanisms during session setup
6 Use cases
7 Recommended requirements
8 Potential solution(s)
9 Conclusion and recommendations
A Determining suitable averaging window length
$ Change history
2 References p. 8
3 Definitions and abbreviations p. 9
3.1 Definitions p. 9
3.2 Abbreviations p. 9
4 Overview p. 9
5 Current QoS reservation mechanisms during session setup p. 10
5.1 System description p. 10
5.2 Simple SDP negotiation and bearer setup p. 11
5.3 Other system aspects p. 12
5.4 Relationship between QoS parameters and rate adaptation p. 12
5.4.1 Introduction p. 12
5.4.2 MBR=GBR bearer p. 13
5.4.3 MBR>GBR bearer p. 13
5.4.4 Different QoS settings in different networks p. 13
6 Use cases p. 14
6.1 General description p. 14
6.2 Use case A: Single fixed-rate speech codec p. 14
6.2.1 General description p. 14
6.2.2 Gap analysis p. 15
6.3 Use case B: Several fixed-rate speech codecs p. 16
6.3.1 General description p. 16
6.3.1.1 Overview p. 16
6.3.1.2 SDP impacts on media handling p. 16
6.3.1.3 Bearer allocation based on first SDP offer/answer p. 17
6.3.1.4 Bearer allocation based on second SDP offer/answer p. 19
6.3.2 Gap analysis after 1st SDP offer/answer p. 20
6.3.2.1 Common p. 20
6.3.2.2 IMS-A chooses Option 1; IMS-B chooses Option 1 p. 20
6.3.2.3 IMS-A chooses Option 2; IMS-B chooses Option 2 p. 21
6.3.2.4 IMS-A chooses Option 1; IMS-B chooses Option 2 p. 21
6.3.2.5 IMS-A chooses Option 2; IMS-B chooses Option 1 p. 22
6.3.2.6 Root-cause analysis when b=AS is used for resource reservation p. 23
6.3.2.7 Root-cause analysis when codec-specific information is used for resource reservation p. 24
6.3.2.8 Handling of over-allocation and under-allocation p. 24
6.3.3 Gap analysis after 2nd SDP offer/answer p. 24
6.4 Use case C: Single multi-rate speech codec (AMR), no extra bandwidth allocated for redundancy p. 25
6.4.1 General description p. 25
6.4.2 Gap analysis p. 28
6.5 Use case D: Single multi-rate speech codec (AMR) with extra bandwidth allocated for redundancy p. 28
6.5.1 General description p. 28
6.5.2 Gap analysis p. 30
6.6 Use case E: Several multi-rate speech codecs (AMR and AMR-WB) p. 30
6.6.1 General description p. 30
6.6.2 Gap analysis p. 31
6.7 Use case F: Single video codec, symmetric usage p. 32
6.8 Use case G: Single video codec, asymmetric usage, sending video with a bitrate matching the codec level p. 35
6.9 Use case H: Single video codec, asymmetric usage, sending video with a bitrate lower than the supported codec level p. 37
6.10 Use case I: Multiple video codecs p. 39
6.11 Use case J: Single video codec, symmetric usage, bitrate variations p. 41
6.11.1 General description p. 41
6.11.2 Gap analysis p. 46
6.12 Use case K: Several multi-rate speech codecs (AMR, AMR-WB and EVS), small difference in EVS usage between operators p. 46
6.12.1 General description p. 46
6.12.2 Gap analysis p. 47
6.13 Use case L: Several multi-rate speech codecs (AMR, AMR-WB and EVS), large difference in EVS usage between operators p. 47
6.13.1 General description p. 47
6.13.2 Gap analysis p. 48
7 Recommended requirements p. 48
7.1 Discussion on individual recommended requirements p. 48
7.1.1 General p. 48
7.1.2 Use case A: Single fixed-rate speech codec p. 48
7.1.3 Use case B: Several fixed-rate speech codecs p. 48
7.1.4 Use case C: Single multi-rate speech codec (AMR), no extra bandwidth allocated for redundancy p. 49
7.1.5 Use case D: Single multi-rate speech codec (AMR) with extra bandwidth allocated for redundancy p. 50
7.1.6 Use case E: Several multi-rate speech codecs (AMR and AMR-WB) p. 50
7.1.7 Use case F: Single video codec, symmetric usage p. 50
7.1.8 Use case G: Single video codec, asymmetric usage, sending video with a bitrate matching the codec level p. 50
7.1.9 Use case H: Single video codec, asymmetric usage, sending video with a bitrate lower than the supported codec level p. 51
7.1.10 Use case I: Multiple video codecs p. 51
7.1.11 Use case J: Single video codec, symmetric usage, bitrate variations p. 51
7.1.12 Use case K: Several multi-rate speech codecs (AMR, AMR-WB and EVS), small difference in EVS usage between operators p. 51
7.1.13 Use case L: Several multi-rate speech codecs (AMR, AMR-WB and EVS), large difference in EVS usage between operators p. 52
7.2 Discussion on proposed requirements for new SDP attributes p. 52
7.3 Discussion on proposed general requirements for the solution p. 52
7.4 Summary of proposed requirements p. 53
7.5 Definition of new bandwidth information parameters p. 54
8 Potential solution(s) p. 55
8.1 Potential solution A: Session re-negotiation p. 55
8.1.1 Introduction p. 55
8.1.2 Description of the solution p. 56
8.1.3 Compliance with proposed requirements p. 56
8.1.4 Impact on networks and terminals p. 56
8.2 Potential solution B: New bandwidth modifiers in SDP offer and answer without SDP MiscCapNeg p. 57
8.2.1 Introduction p. 57
8.2.2 Description of the solution p. 57
8.2.2.1 General solution p. 57
8.2.2.2 New bandwidth modifiers p. 57
8.2.2.3 Procedures p. 58
8.2.2.4 Session negotiation example p. 58
8.2.2.5 Modifying the bandwidth information in the SDP offer p. 60
8.2.2.6 Resource reservation in different networks p. 60
8.2.3 Compliance with proposed requirements p. 61
8.2.4 Impact on networks and terminals p. 61
8.3 Potential solution C: New bandwidth modifiers and SDPMiscCapNeg in SDP offer and answer p. 61
8.3.1 Introduction p. 61
8.3.2 Description of the solution p. 61
8.3.2.1 General solution p. 61
8.3.2.2 Procedures p. 62
8.3.2.3 Session negotiation example p. 62
8.3.2.4 Modifying the bandwidth information in the SDP offer p. 63
8.3.2.5 Resource reservation in different networks p. 64
8.3.3 Compliance with proposed requirements p. 64
8.3.4 Impact on networks and terminals p. 64
8.4 Potential solution D: New attribute for bandwidth information in SDP offer and answer for each RTP payload type p. 65
8.4.1 Introduction p. 65
8.4.2 Description of the solution p. 65
8.4.2.1 General solution p. 65
8.4.2.2 New attribute p. 65
8.4.2.3 Procedures p. 66
8.4.2.4 Session negotiation example p. 66
8.4.2.5 Modifying the bandwidth information in the SDP offer p. 66
8.4.2.6 Resource reservation in different networks p. 67
8.4.3 Compliance with proposed requirements p. 67
8.4.4 Impact on networks and terminals p. 67
8.5 Potential solution E: New bandwidth modifiers only in SDP answer p. 67
8.5.1 Introduction p. 67
8.5.2 Description of the solution p. 67
8.5.2.1 General solution p. 67
8.5.2.2 New bandwidth modifiers p. 67
8.5.2.3 Session negotiation example p. 67
8.5.2.4 Modifying the bandwidth information in the SDP offer p. 68
8.5.2.5 Resource reservation in different networks p. 68
8.5.3 Compliance with proposed requirements p. 68
8.5.4 Impact on networks and terminals p. 68
8.6 Potential solution F: New SDP attribute in SDP offer and answer for entire media line p. 68
8.6.1 Introduction p. 68
8.6.2 Description of the solution p. 68
8.6.2.1 General solution p. 68
8.6.2.2 New SDP attribute p. 69
8.6.2.3 Procedures p. 69
8.6.2.4 Session negotiation example p. 69
8.6.2.5 Modifying the bandwidth information in the SDP offer p. 69
8.6.2.6 Resource reservation in different networks p. 70
8.6.3 Compliance with proposed requirements p. 70
8.6.4 Impact on networks and terminals p. 70
8.7 Potential solution G: New SDP attribute only in SDP answer p. 70
8.7.1 Introduction p. 70
8.7.2 Description of the solution p. 70
8.7.2.1 General solution p. 70
8.7.2.2 New SDP attribute p. 71
8.7.2.3 Procedures p. 71
8.7.2.4 Session negotiation example p. 71
8.7.2.5 Modifying the bandwidth information in the SDP offer p. 71
8.7.2.6 Resource reservation in different networks p. 71
8.7.3 Compliance with proposed requirements p. 71
8.7.4 Impact on networks and terminals p. 72
8.8 Potential solution H: Bitrate variations p. 72
9 Conclusion and recommendations p. 73
A Determining suitable averaging window length p. 74
A.1 Introduction p. 74
A.2 Suitable averaging window for video p. 74
A.2.1 Reasonable video encoder configuration p. 74
A.2.2 Normal transmission p. 74
A.2.3 Sending a large I frame p. 75
A.2.4 Compensating for a large I frame p. 75
A.2.5 Sending an even larger I frame p. 76
A.2.6 Using a longer averaging window p. 77
A.2.7 Selection of averaging window length p. 77
A.3 Other services p. 78
$ Change history p. 80
