E.4 Bi-directional real-time text (3 kbps, IPv4 or IPv6, RTCP and MBR=GBR bearer)
26.1143GPPIP Multimedia Subsystem (IMS)Media handling and interactionMultimedia telephonyRelease 18TS
Bi-directional text at 3 kbps all inclusive (text, IP overhead, RTCP).
Table E.3: QoS mapping for bi-directional real-time text (3 kbps, IPv4, RTCP and MBR=GBR bearer) when using a conversational class bearer
|
Traffic class |
Conversational class |
Notes |
|
Delivery order |
No |
The application should handle packet reordering. |
|
Maximum SDU size (octets) |
1400 |
Maximum size of IP packets |
|
Delivery of erroneous SDUs |
No |
|
|
Residual BER |
10-5 |
Reflects the desire to have a medium level of protection to achieve an acceptable compromise between packet loss rate and speech transport delay and delay variation. |
|
SDU error ratio |
1*10-3 |
Text should have a higher level of protection than voice and video. |
|
Transfer delay (ms) |
130 ms |
Indicates maximum delay for 95th percentile of the distribution of delay for all delivered SDUs between the UE and the PS domain during the lifetime of a bearer service. Permits the derivation of the RAN part of the total transfer delay for the radio access bearer. This attribute allows RAN to set transport formats and H-ARQ/ARQ parameters such as the discard timer. |
|
Guaranteed bitrate for uplink (kbps) |
3.0 |
An assumed total bit-rate of a real-time text service including headers and RTCP. |
|
Maximum bitrate for uplink (kbps) |
3.0 |
The same as the guaranteed bitrate. |
|
Guaranteed bitrate for downlink (kbps) |
3.0 |
An assumed total bit-rate of a real-time text service including headers and RTCP. |
|
Maximum bitrate for downlink (kbps) |
3.0 |
The same as the guaranteed bitrate. |
|
Allocation/Retention priority |
Subscribed value |
Indicates the relative importance to other radio access bearers. It should be a lower value to the priority of a Conversational bearer with source statistics descriptor ‘speech’. |
|
Source statistics descriptor |
‘unknown’ |
Using a conversational class bearer means that resources are reserved throughout the session. Depending on the intended usage of real-time text, it might not be the most resource efficient choice to use a conversational class bearer, especially if it is foreseen that the sessions will be long-lived while the actual text conversations will be rare and bursty. Table E.4 therefore shows an example with QoS mapping for using an interactive class bearer. It is recommended to use QCI 6, 8, or 9 [90] for T.140 real-time text unless the service policy decides to assign different QCI types.
Table E.4: QoS mapping for bi-directional real-time text (3 kbps, IPv4, RTCP) when using an interactive bearer
|
Traffic class |
Interactive class |
Notes |
|
Delivery order |
No |
In sequence delivery is not required |
|
Maximum SDU size (octets) |
1400 |
Maximum size of IP packets |
|
Delivery of erroneous SDUs |
No |
|
|
Residual BER |
10-5 |
Reflects the desire to have a medium level of protection to achieve an acceptable compromise between packet loss rate and voice transport delay and delay variation. |
|
SDU error ratio |
10-4 |
Text should have a higher level of protection than voice and video. |
|
Maximum bitrate (kbps) |
[Depending on UE category] |
Should be set as high as the UE category can handle |
|
Allocation/Retention priority |
Subscribed value |
Indicates the relative importance to otherradio access bearers. It should be a lower value to the priority of a Conversational bearer with source statistics descriptor ‘speech’. |
|
Traffic handling priority |
3 |
|
|
Signalling indication |
‘No’ |
Table E.5: QoS mapping for bi-directional real-time text (3 kbps, IPv6, RTCP and MBR=GBR bearer) when using a conversational class bearer
|
Traffic class |
Conversational class |
Notes |
|
Delivery order |
No |
The application should handle packet reordering. |
|
Maximum SDU size (octets) |
1400 |
Maximum size of IP packets |
|
Delivery of erroneous SDUs |
No |
|
|
Residual BER |
10-5 |
Reflects the desire to have a medium level of protection to achieve an acceptable compromise between packet loss rate and speech transport delay and delay variation. |
|
SDU error ratio |
1*10-3 |
Text should have a higher level of protection than voice and video. |
|
Transfer delay (ms) |
130 ms |
Indicates maximum delay for 95th percentile of the distribution of delay for all delivered SDUs between the UE and the PS domain during the lifetime of a bearer service. Permits the derivation of the RAN part of the total transfer delay for the radio access bearer. This attribute allows RAN to set transport formats and H-ARQ/ARQ parameters such as the discard timer. |
|
Guaranteed bitrate for uplink (kbps) |
4.0 |
An assumed total bit-rate of a real-time text service including headers and RTCP. |
|
Maximum bitrate for uplink (kbps) |
4.0 |
The same as the guaranteed bitrate. |
|
Guaranteed bitrate for downlink (kbps) |
4.0 |
An assumed total bit-rate of a real-time text service including headers and RTCP. |
|
Maximum bitrate for downlink (kbps) |
4.0 |
The same as the guaranteed bitrate. |
|
Allocation/Retention priority |
Subscribed value |
Indicates the relative importance to other radio access bearers. It should be a lower value to the priority of a Conversational bearer with source statistics descriptor ‘speech’. |
|
Source statistics descriptor |
‘unknown’ |