RTC SWG Report Post SA4#134

Executive Summary

The RTC SWG held two adhoc calls post SA4#134 with 15 input contributions and 24 participants in the first adhoc, and 10 input contributions and 30 attendees in the second adhoc. Two tdocs were agreed.

Key Outcomes by Work Item:

• AIML_IMS_MED: Agreed to create one CR to TS 26.114 as output. Based on SA2 LS response, agreed to complete work with local/split/remote on DC AS (instead of MF) and document limitations. Agreed on device-inference call flow as basis for further work.
• FS_DCTC_eQOS_MED: Discussion on test platform continued.
• FS_Q4RTC_MED: Agreed on work plan and discussed TR skeleton and basic QUIC protocol.

AIML_IMS_MED (Media Aspects for AI/ML in IMS Services)

Scope Definition and Architecture

S4aR250216 - Scope in Light of SA2 LS

The group discussed the scope following the SA2 liaison response. Key decisions:

• Agreed to complete work with local/split/remote inferencing on the DC AS (Data Channel Application Server) rather than the MF (Media Function)
• Document limitations (e.g., DC AS not present for P2P case, so only UE inferencing may be possible for P2P)
• Send LS to SA2 with more details on SA4's needs and scope
• Take approach similar to Annex AC P2P and P2A2P: MF as relay, same approach for remote/split (P2A2P) and local (P2P)

Call Flows

S4aR260004/S4aR260014 - Call Flow for Device Inferencing

Joint contribution from Samsung and InterDigital. After extensive discussion:

• Agreed as basis for further work with modifications:
• Steps 8-9 (model fetching by MF before application data channel establishment) removed
• Editor's notes added regarding:
  • How to handle large models
  • Network capability considerations
  • Model selection mechanisms
  • Caching requirements in UE

Key discussion points:
- Model sizes can be significant (e.g., 80 MB), requiring consideration of download time and network impact
- Application metadata would indicate supported tasks; JavaScript in application can check UE capabilities
- MF acts as HTTP proxy and can cache
- Need for both UE-side and network-side caching solutions
- Partial model updates and model compression need to be addressed

S4aR250205 - Call Flow for Device Inferencing (Samsung)

Initial proposal that was merged into S4aR260004. Noted for further work.

S4aR260007 - Call Flow for Device Inferencing Update (InterDigital)

Discussion focused on:
- Clarification needed on whether this replaces normal BDC bootstrap procedures
- Terminology should be moderated to clarify high-level stage 2 description
- Protocol details need refinement

S4aR250206 - Call Flow for Network Inferencing

Noted. Needs update to reflect inferencing on DC AS instead of MF. Questions raised about model download source (DCAR vs DC AS).

S4aR250207/S4aR260008 - Call Flow for Split Inferencing

Noted. Similar to network inferencing but for split scenarios. Needs update to have split inferencing on DC AS rather than MF. Parameters in request/response messages need synchronization with other proposals.

S4aR250218 - Update Call Flow for Local/Remote/Split AIML Inferencing (InterDigital)

Noted. Needs update due to MF/DC AS changes. Proposed two data channels: one for configuration and one for data exchange. Terminology modifications needed for steps 1 and 3.

Task and Model Management

S4aR250208 - On AI Application Tasks and Subtasks

Noted. Discussion on whether to use subtask concept or stay with application/task/model terminology. Clarity needed on subtask definition before adoption.

S4aR250209/S4aR260006 - AI/ML Media Processing and Task Updating (Nokia)

Noted. Addresses task reselection and task update scenarios:
- Task update vs. new task may require different procedures
- Distinction between updating a model vs. adding new capabilities (e.g., translation language)
- In P2P case, may need application data channel
- Clarification needed on whether "network functions" refers to MF or other entities

S4aR250211 - Adaptive Model Delivery (Nokia)

Noted. Proposes two cases:
1. Standard model delivery
2. Adaptive delivery with MF as proxy

Discussion points:
- Need clarification on model selection process (UE, user, or other entity)
- Low precision and incremental model updates need more description
- Make model update optional in second case

Application Manifest and Negotiation

S4aR250213/S4aR260011 - On Application Manifest for AIML Applications (Nokia)

Noted. Proposes JSON format for application manifest with metadata. Needs alignment with other contributions. Email discussion to be triggered on this topic.

S4aR260009/S4aR260012 - Negotiation Messages (InterDigital)

Noted. Proposes metadata for negotiation messages. Questions raised:
- Where will application info format be used?
- Are we defining a new DC protocol?
- Motivation is to identify what metadata needs to be considered

S4aR260010 - Negotiation Messages for Split Inferencing

Noted. Needs revision to sync with basic call flows.

Codec and Compression

S4aR260005 - On NNC Decoding in Web Environment (Fraunhofer HHI, Nokia)

Noted. Discussion on Neural Network Coding (NNC) decoder in web environment. No alternative decoder currently available. Comparison document to be shared on differences.

Specification Strategy

S4aR250215 - Discussion on TS

Agreed to add an annex to TS 26.114 and prepare CR accordingly. Consensus for smaller scope with annex in 26.114 rather than separate specification.

S4aR250217/S4aR250220 - Draft CR on AIML Processing in IMS Calls

Noted. Will be developed as CR to TS 26.114 based on agreed scope.

FS_DCTC_eQOS_MED (Study on Usage of Dynamically Changing Traffic Characteristics and Enhanced QoS Support)

Technical Report

S4aR250212 - Draft TR 26.823

Noted. Presented for information. Issues identified:
- No revision marks and incorrect version number
- Missing agreed document numbers in change history
- Style conformance issues
- Skeleton was only agreed in closing plenary

Expected revision for next adhoc with:
- Change marks
- ETSI style compliance
- Agreed documents listed in annex
- Correct version number

Evaluation Strategy

S4aR250219 - Evaluation Testing Strategy Proposal (InterDigital)

Noted. Discussion points:
- Network impairment testing vs. in-the-field testing needs more work
- No need to limit to one evaluation platform
- RTT measurement possible also for QUIC
- Need details on "specific" platform and parameter sources
- Which specific application for AI testing
- Hard to set up OPs for OTT; need reference platform with control
- Joint meeting with other evaluation/studies to develop common evaluation framework
- Reference to 26.955 for joint discussion
- QoE metrics handling needs resolution

FS_Q4RTC_MED (Study on QUIC for RTC Media)

Work Plan

S4aR250210/S4aR250221 - Draft Work Plan for FS_Q4RTC_MED

Agreed (S4aR250221). Discussion points:
- Note on normative work to be triggered before end of study
- Evaluation work needs alignment with other studies
- Need clear item in timeplan on common evaluation framework
- Coordination with QStream starting from Goa meeting
- Careful on "common" aspects as different tools may be needed

Protocol Overview

S4aR260001/S4aR260013 - Overview of QUIC-based Media Delivery Protocols (Nokia)

Noted (S4aR260013). Good base document. Comments to be provided by email on requirements and other aspects.

Technical Report Skeleton

S4aR260003 - Draft TR 26.836 v0.0.1 (Skeleton) (NTT, Nokia)

Noted. Issues identified:
- Clause 4.2.3 number missing
- Some existing content can be moved to annex
- Pros and cons need clarification (for RTC or general?)
- Introduction/title of 5.3: F→Functional
- Consider including evaluation under each application scenario
- Version number needs offline check with Andrijana

Meeting Details

First Adhoc Call:
- Date: December 17, 2025, 14:00-16:21 CET
- Host: Nokia
- 15 input contributions, 24 participants

Second Adhoc Call:
- Date: January 28, 2026, 15:00-17:15 CET
- Host: Nokia
- 10 input contributions, 30 attendees

Minutes taken by Gaëlle Martin-Cocher (first adhoc) and Bo Burman/Shane He (second adhoc).