Specify methods in the M6/M11 Media Session Handling client API to invoke 5GMS network assistance

[rjb1000]

Context

The 5GMS architecture defined in TS 26.501 specifies two different forms of network assistance that a 5GMS Client can request from the 5GMS AF:

• Bandwidth estimation. The 5MGS AF provides an estimate of the bit rate that the network can currently sustain in the 5GMS Client's current M4 PDU Session.
• Temporary bit rate boost. The 5GMS Client requests a temporary boost to the bit rate of its current M4 PDU Session. This could be used, for example, by the Media Player to replenish its media segment buffer in the event that it falls below some critical occupancy threshold.

TR 26.804 studied the feasibility of extending this repertoire to include:

• Background download. (See clause 5.6 of TR 26.804.) The 5GMS Client requests a reduction in the bit rate of its current M4 PDU Session to download some content in non-real time, perhaps in return for the download being zero rated by the network operator.

Description

TS 26.512 does not currently specify a client API at reference point M6d for the 5GMS-Aware Application or Media Stream Handler (downlink Media Player or uplink Media Streamer) to request network assistance from the Media Session Handler.

Nor does it specify a mechanism for the Media Session Handler to pass on bit rate recommendations to the Media Stream Handler that have been received from the 5GMS AF or from the UE RAN modem.

Suggested solution

Specify suitable methods and notifications in TS 26.512 clause 12 to close this gap. This could be achieved in the (currently empty) clause 12.2.5.

It is recommended to make this change in Rel-16 onwards.

Additional considerations

The methods specified should be applicable to uplink media streaming as well as downlink media streaming. Because clause 12.2 in TS 26.512 applies only to downlink media streaming, the clause structure may need to be revised to define a common API for both directions of media streaming.

[rjb1000]

At SA4#127-bis-e, @irajs from Tencent proposed some media session handling client APIs at reference point M6/M11:

• TS 26.512
  • Rel-16: No contribution.
  • Rel-17: No contribution.
• TS 26.510
  • Rel-18 pCR "[5GMS_Pro_Ph2] 26.510: Improvements on clause 10" in S4-240673.

[rjb1000]

The contribution from Tencent was revised during the SA4#127-bis-e meeting to:

• TS 26.512
  • Rel-16: No contribution.
  • Rel-17: No contribution.
• TS 26.510
  • Rel-18 pCR "[5GMS_Pro_Ph2] 26.510: Improvements on clause 10" in S4-240835.

The revision was noted.

[rjb1000]

New specification versions published following approval of CRs at SA#104:

• TS 26.510
  • Rel-18: V18.0.2.

This includes limited improvements to the Network Assistance Client API (clause 11.4 of TS 26.510) contributed by Tencent in pCR S4-241196, but these improvements are limited to the notification and error events.

The methods for requesting bit rate recommendations and delivery boost remain unspecified.

For that reason, I am leaving this issue open, and will push to the next meeting cycle milestone.