A.1 Video enhancements

26.2363GPPPacket switched conversational multimedia applicationsTransport protocolsTS

This clause gives informative recommendations for the video media type control.

The SDP attributes regarding the video frame rate and the quality of media encoding should be used to ensure good video service. The recommended usage of these attributes are FFS.

a=framerate:<frame rate> describes the maximum video frame rate attribute in frames/second. Fractional values of <frame rate> are allowed.

a=quality:<quality> describes the quality of media encoding attribute, where the <quality> is a value in [0..10] with 10 indicating the best quality.

Annex B (informative):
Mapping of SDP parameters to UMTS QoS parameters

This clause gives recommendations for mapping of SDP parameters in UMTS QoS parameters for conversational multimedia applications. Different use cases will be considered. Each use case generates an example QoS profile parameters table table (with values for IPv4 and IPv6 addressing). The values indicated are derived by applications’ QoS requirements, and may not be fulfilled by the network. In the parameters for guaranteed and maximum bit rates a granularity of 1 kbps is assumed for bearers up to 64 kbps, as defined in the TS 24.008. Therefore the "Ceiling" function is used for up-rounding fractional values, wherever needed. In addition, the same specification defines a granularity of 10 bytes for the Maximum SDU sizes values. This is taken into account in the computation of this field in the QoS profile.

Use case 1 – Voice over IP

This use case includes the scenario in which two conversational multimedia terminals establish a bi-directional Voice over IP (VoIP) connection for speech communication, using the AMR or AMR-WB codecs with the same bit rate in both uplink and downlink directions.

For example an AMR VoIP stream encoded at 12.2 kbps, with one speech frame encapsulated into an RTP packet, would yield IP packets of the following size (using the mandated bandwidth efficient mode):

20 (IPv4) + 8 (UDP) + 12 (RTP) + 32 (AMR RTP payload) = 72 bytes, or

40 (IPv6 with no extension headers) + 8 (UDP) + 12 (RTP) + 32 (AMR RTP payload) = 92 bytes.

The gross bit rate including uncompressed RTP/UDP/IPv4 headers would be 28.8 kbps. The value in the b=AS media level parameter would be 29. The gross bit rate including uncompressed RTP/UDP/IPv6 headers would be 36.8 kbps. The value in the b=AS media level parameter would be 37.

To determine the Maximum SDU size parameter we should consider the maximum packet size that can be generated with a speech codec. This is exactly that generated by a AMR-WB stream at 23.85 kbps packetized in bandwidth efficient mode and with 1 speech frame per packet. Considering uncompressed RTP/UDP/IPv6 headers, the maximum packet size is 121 bytes.

The QoS profile would be set then using the following parameters:

Table B.1: QoS profile for AMR VoIP at 12.2 kbps

QoS parameter

Parameter value

Comment

Delivery of erroneous SDUs

No

Delivery order

No

To minimize delay in the access stratum. The application should take care of eventual packet reordering

Traffic class

Conversational

Maximum SDU size

130 bytes

10 bytes granularity.

The RTCP packet size might change the maximum SDU size limitation [tbc]

Guaranteed bitrate for downlink

SDP media bw in DL +

2.5% * (SDP media bw in DL+ SDP media bw in UL) =

Ceil(30.45)=31 kbps (for the IPv4 case)

Ceil(38.85)=39 kbps (for the IPv6 case)

Maximum bit rate for downlink

Ceil(30.45)=31 kbps (for the IPv4 case)

Ceil(38.85)=39 kbps (for the IPv6 case)

Guaranteed bitrate for uplink

SDP media bw in UL +

2.5% * (SDP media bw in UL+ SDP media bw in DL) =

Ceil(30.45)=31 kbps (for the IPv4 case)

Ceil(38.85)=39 kbps (for the IPv6 case)

Maximum bit rate for uplink

Ceil(30.45)=31 kbps (for the IPv4 case)

Ceil(38.85)=39 kbps (for the IPv6 case)

Residual BER

10-5

16 bit CRC

SDU error ratio

7*10-3

Traffic handling priority

Not used in Conversational traffic class

Transfer delay

100 ms

SDU format information

Not used

Allocation/retention priority

Subscribed allocation/retention priority

Not relevant for the application

Source statistics descriptor

"Speech"

In some cases, multiple AMR or AMR-WB rates are available, and rate control techniques allow to switch between different modes based on the received speech quality. For example, if the available AMR mode set is {4.75, 10.2, 12.2} kbps, the set of gross bit rates are:

AMR 4.75 kbps: 21.6 kbps (including RTP/UDP/IPv4 headers). [SDP b=AS parameter would be 22].

AMR 10.2 kbps: 26.8 kbps (including RTP/UDP/IPv4 headers). [SDP b=AS parameter would be 27].

AMR 12.2 kbps: 28.8 kbps (including RTP/UDP/IPv4 headers). [SDP b=AS parameter would be 29].

In case of IPv6 addressing, the gross bit rates are:

AMR 4.75 kbps: 29.6 kbps (including RTP/UDP/IPv6 headers). [SDP b=AS parameter would be 30].

AMR 10.2 kbps: 34.8 kbps (including RTP/UDP/IPv6 headers). [SDP b=AS parameter would be 35].

AMR 12.2 kbps: 36.8 kbps (including RTP/UDP/IPv6 headers). [SDP b=AS parameter would be 37].

The maximum bit rate is set to the highest mode of the codec. However, the procedure on how to choose the guaranteed bit rate when several codec rates are available is to be defined. Here we provide an example QoS profile in which the guaranteed speech quality is at least that of 10.2 kbps AMR for both uplink and downlink directions, while the non-guaranteed maximum quality is that of 12.2 kbps for both uplink and downlink directions.

Table B.2: QoS profile for AMR VoIP at 3 bit rates with rate control

QoS parameter

Parameter value

Comment

Delivery of erroneous SDUs

No

Delivery order

No

To minimize delay in the access stratum. The application should take care of eventual packet reordering

Traffic class

Conversational

Maximum SDU size

130 bytes

10 bytes granularity.

The RTCP packet size might change the maximum SDU size limitation [tbc]

Guaranteed bitrate for downlink

SDP media bw in DL +

2.5% * (SDP media bw in DL+ SDP media bw in UL) =

Ceil(28.35)=29 kbps (for the IPv4 case)

Ceil(36.75)=37 kbps (for the IPv6 case)

Guaranteed quality 10.2 kbps

Maximum bit rate for downlink

SDP media bw in DL +

2.5% * (SDP media bw in DL+ SDP media bw in UL) =

Ceil(30.35)=31 kbps (for the IPv4 case)

Ceil(38.85)=39 kbps (for the IPv6 case)

Non-guaranteed quality 12.2 kbps

Guaranteed bitrate for uplink

SDP media bw in UL+

2.5% * (SDP media bw in UL+ SDP media bw in DL) =

Ceil(28.35)=29 kbps (for the IPv4 case)

Ceil(36.75)=37 kbps (for the IPv6 case)

Guaranteed quality 10.2 kbps

Maximum bit rate for uplink

SDP media bw in UL +

2.5% * (SDP media bw in UL+ SDP media bw in DL) =

Ceil(30.35)=31 kbps (for the IPv4 case)

Ceil(38.85)=39 kbps (for the IPv6 case)

Non-guaranteed quality 12.2 kbps

Residual BER

10-5

16 bit CRC

SDU error ratio

7*10-3

Traffic handling priority

Not used in Conversational traffic class

Transfer delay

100 ms

SDU format information

Not used

Allocation/retention priority

Subscribed allocation/retention priority

Not relevant for the application

Source statistics descriptor

"Speech"

Use case 2 – Unidirectional video

This use case includes the scenario in which two conversational multimedia terminals establish a uni-directional video connection, using the H.263, H.264 or MPEG-4 codecs.

The video codec in this example has a bitrate of 36 kbps, with RTP payload packets of 75 bytes (excluding payload header which is, for example, 2 bytes). The sending terminal would produce IP packets of the following size:

20 (IPv4) + 8 (UDP) + 12 (RTP) + 77 (video RTP payload+payload header) = 117 bytes, or

40 (IPv6 with no extension headers) + 8 (UDP) + 12 (RTP) + 77 (video RTP payload+payload header) = 137 bytes.

The gross bit rate including uncompressed RTP/UDP/IPv4 headers would be 56.2 kbps. The value in the b=AS media level parameter would be 57. The gross bit rate including uncompressed RTP/UDP/IPv6 headers would be 65.8 kbps. The value in the b=AS media level parameter would be 66.

The maximum video packet size is limited to 512 bytes in section 5.2. This value is fine if transmission occurs over the UMTS Iu interface. However, in order to avoid SNDCP fragmentation of packets over the GERAN Gb interface (where the default size for LLC data field (=SNDCP frame) is 500 bytes) the maximum IP packet size is 500 – 4 (unacknowledged mode SNDCP header) = 496 bytes. Therefore, the maximum size of a video packet is 496 – 60 (RTP/UDP/IPv6 uncompressed headers) = 436 bytes (including RTP payload header). 400 bytes is a safer value.

The QoS profile of the receiving terminal would be set then using the following parameters:

Table B.3: QoS profile for unidirectional video at 36 kbps

QoS parameter

Parameter value

Comment

Delivery of erroneous SDUs

No

Delivery order

No

To minimize delay in the access stratum. The application should take care of eventual packet reordering

Traffic class

Conversational

Maximum SDU size

500 bytes

10 bytes granularity

Guaranteed bitrate for downlink

SDP media bw in DL +

2.5% * (SDP media bw in DL) = Ceil(58.43)=59 kbps (for the IPv4 case) Ceil(67.65)=68 kbps (for the IPv6 case)

Maximum bit rate for downlink

Equal or higher than guaranteed bit rate

Guaranteed bitrate for uplink

2.5% * (SDP media bw in DL) =

Ceil(1.43)=2 kbps (for the IPv4 case)

Ceil(1.65)=2 kbps (for the IPv6 case)

For RTCP

Maximum bit rate for uplink

Equal or higher than guaranteed bit rate

Residual BER

10-5

16 bit CRC

SDU error ratio

10-3

Traffic handling priority

Not used in Conversational traffic class

Transfer delay

250 ms

SDU format information

Not used

Allocation/retention priority

Subscribed allocation/retention priority

Not relevant for the application

Source statistics descriptor

"Unknown"

Use case 3 – Video telephony

This use case includes the scenario in which two conversational multimedia terminals establish a bi-directional speech/video connection, using the AMR/AMR-WB and H.263/H.264/MPEG-4 codecs at the same bit rates in uplink and downlink directions.

The video codec in this case has a bitrate of 28 kbps, with RTP payload packets of 250 bytes (excluding payload header which is, for example, 2 bytes). The total video bit rate is 32.7 kbps (including RTP/UDP/IPv4 headers). The value in the b=AS media level parameter would be 33. For IPv6 addressing, the total video bit rate is 34.9 kbps (including RTP/UDP/IPv6 headers). The value in the b=AS media level parameter would be 35.

In the same bearer there is an AMR stream at 10.2 kbps with 1 frame encapsulated per RTP packet using the bandwidth efficient mode. The total voice bit rate is 26.8 kbps (including RTP/UDP/IPv4 headers). The value in the b=AS media level parameter would be 27. For IPv6 addressing, the total voice bit rate is 34.8 kbps (including RTP/UDP/IPv6 headers). The value in the b=AS media level parameter would be 35.

The total media bit rate is 28+10.2=38.2 kbps. The total session bit rate is 33+27=60 kbps kbps for IPv4 addressing, and 35+35=70 kbps for IPv6 addressing.

The terminal would produce IP packets of the following size:

AMR: 20 (IPv4) + 8 (UDP) + 12 (RTP) + 27 (AMR RTP payload) = 67 bytes (or 87 bytes for IPv6 with no extension headers).

Video: 20 (IPv4) + 8 (UDP) + 12 (RTP) + 252 (video RTP payload+payload header) = 292 bytes (or 312 bytes for IPv6 with no extension headers).

The same considerations done in Use Case 2 about the maximum packet sizes apply also for this use case.

The QoS profile of the videotelephony terminal would be set then using the following parameters:

Table B.4: QoS profile for videotelephony at 38.2 kbps

QoS parameter

Parameter value

Comment

Delivery of erroneous SDUs

No

Delivery order

No

To minimize delay in the access stratum. The application should take care of eventual packet reordering

Traffic class

Conversational

Maximum SDU size

500 bytes

10 bytes granularity

Guaranteed bitrate for downlink

SDP media bw in DL for AMR +

2.5% * (SDP media bw in DL for AMR+ SDP media bw in UL for AMR) +

SDP media bw in DL for video +

2.5% * (SDP media bw in DL for video+ SDP media bw in UL for video)

= Ceil(63.0)=63 kbps (for the IPv4 case)

= Ceil(73.3)=74 kbps (for the IPv6 case)

Maximum bit rate for downlink

Equal or higher than guaranteed bit rate

Guaranteed bitrate for uplink

SDP media bw in UL for AMR +

2.5% * (SDP media bw in UL for AMR+ SDP media bw in DL for AMR) +

SDP media bw in UL for video +

2.5% * (SDP media bw in UL for video+ SDP media bw in DL for video)

= Ceil(63.0)=63 kbps (for the IPv4 case)

= Ceil(73.3)=74 kbps (for the IPv6 case)

Maximum bit rate for uplink

Equal or higher than guaranteed bit rate

Residual BER

10-5

16 bit CRC

SDU error ratio

10-3

Traffic handling priority

Not used in Conversational traffic class

Transfer delay

100 ms

SDU format information

Not used

Allocation/retention priority

Subscribed allocation/retention priority

Not relevant for the application

Source statistics descriptor

"Unknown"

In case of usage of separate PDP contexts for the speech and video streams, the speech stream QoS profile parameters are set similarly to use case 1, while the video stream QoS profile parameters are set similarly to use case 2 (but considering that the video flow is bi-directional and considering possibly the same UMTS bearer transfer delay constraints for both media).

Annex C (informative):
Change history

Change history

Date

TSG #

TSG Doc.

CR

Rev

Subject/Comment

Old

New

2002-03

15

SP-020074

Version 2.0.0 presented for approval

2.0.0

5.0.0

2002-12

18

SP-020695

001

2

QoS profile parameters for conversational multimedia applications

5.0.0

5.1.0

2002-12

18

SP-020695

002

1

Clarification on SDP session bandwidth parameter

5.0.0

5.1.0

2003-03

19

SP-030092

003

2

SDP bandwidth modifier for RTCP bandwidth

5.1.0

5.2.0

2003-03

19

SP-030092

004

Correction on QoS profile parameters for conversational multimedia applications

5.1.0

5.2.0

2003-06

20

SP-030219

005

Examples of QoS profiles for conversational multimedia applications

5.2.0

5.3.0

2003-09

21

SP-030449

006

Correction of obsolete RTP references

5.3.0

5.4.0

2003-09

21

SP-030449

007

1

Correction of wrong reference

5.3.0

5.4.0

2004-06

24

SP-040356

010

3

Introduction of the DSR codec

5.4.0

6.0.0

2004-06

24

SP-040357

012

RTCP usage for IMS

5.4.0

6.0.0

2004-12

26

SP-040843

013

1

Inclusion of PoC support

6.0.0

6.1.0

2005-03

27

SP-050099

015

1

Introduction of AMR SDP parameters

6.1.0

6.2.0

2005-06

28

SP-050249

017

1

Clarification to the Introduction of AMR SDP parameters

6.2.0

6.3.0

2005-09

29

SP-050424

0018

1

Clarifications on RTP Session Description Parameters for PoC

6.3.0

6.4.0

2006-03

31

SP-060219

0019

3

Update of a RFC on real time text and DSR codec

6.4.0

7.0.0

2006-09

33

SP-060598

0021

1

Symmetric RTP and RTCP Port Usage

7.0.0

7.1.0

2007-09

37

SP-070627

0023

Correction of references

7.1.0

7.2.0

2008-03

39

SP-080009

0024

1

Correction of RTP usage for audio for PS conversational multimedia applications

7.2.0

7.3.0

2008-12

42

Version for Release 8

7.3.0

8.0.0

2009-12

46

Version for Release 9

8.0.0

9.0.0

2011-03

51

Version for Release 10

9.0.0

10.0.0

2012-09

57

Version for Release 11

10.0.0

11.0.0

2014-09

65

Version for Release 12

11.0.0

12.0.0