3GPP Technical Document Summary: CR 0003 Rev 1 for TS 26.813 (Avatar Services)

Document Overview

This is a Category F (correction) Change Request for TS 26.813 Release 19, version 19.1.0, addressing editorial corrections and reference updates across multiple sections of the Avatar specification.

Main Technical Contributions

Section 2: References Updates

• Corrected normative and informative references including:
• Updated 3GPP TR 22.856 to V19.2.0 (Localized Mobile Metaverse Services)
• Updated 3GPP TS 23.228 to V19.2.0 (IMS Stage 2)
• Corrected formatting and accessibility information for external references (AFLW, LFPW, WFLW datasets)
• Added new reference [34] for I.-J. Hirsh and C. E. Sherrick study on perceived order in different sense modalities
• Added new reference [35] for Hyojin Park et al. study on lip movements and brain oscillations

Section 5: Use Cases and Potential Requirements

UC1: Avatar Communication

Editorial corrections:
- Removed duplicate requirement regarding bidirectional transitioning between video and avatar media
- Clarified voice-driven avatar animation requirements
- Enhanced description of audio-visual synchronization for accessibility

Key technical aspects maintained:
- Real-time facial expression and body movement metadata extraction based on ASR/NLP
- Voice-driven 2D/3D avatar animation generation and encoding/decoding
- Avatar sharing, modification, and real-time composing capabilities
- Lip movement synchronization for enhanced intelligibility in noisy environments

UC2: Multi-party Shared Experiences

Corrections:
- Refined description of collaborative working scenarios
- Added specific use case for classroom environments with differential avatar expression control
- Added teenage social gathering scenario with selective expression filtering

Technical requirements:
- Secure end-to-end avatar expression delivery for specific audiences
- Network-based capability for filtering/replacing avatar expressions for selected audiences
- Support for filtering or replacing selected subsets of face and body expressions during avatar animation generation

UC3: Multi-user Gaming

Editorial improvements:
- Clarified synchronization requirements between different modalities
- Updated KPI requirements with proper formatting

Key synchronization thresholds maintained:
- Audio-tactile: 12ms (audio first), 25ms (tactile first)
- Visual-tactile: 30ms (video first), 20ms (tactile first)
- Audio-visual: 20ms (audio first), 20ms (video first)

KPI requirements:
- End-to-end latency: 5-20ms
- Service bit rate: 1-1000 Mbit/s
- Positioning accuracy: <1m

UC4: Avatar Generation, Storage, and Access

Corrections:
- Reformatted requirements section for clarity
- Consolidated requirements from TR 22.856
- Enhanced description of avatar lifecycle management

Technical requirements:
- Avatar generation, update, and animation support (UE and/or network-based)
- Avatar metadata for parental control and access management
- Discovery and negotiation of network functions for avatar processing
- Upload, storage, search, transmission, and update capabilities
- Avatar identification and mapping to subscribers
- Authorization and usage rights management

UC5: AI-Based Avatar

Editorial updates:
- Clarified autonomous virtual alter ego concept
- Enhanced description of AI avatar capabilities

Technical requirements:
- AI/ML model transfer per TR 23.700-80 framework
- Secure registration, storage, and updating of AI-based avatars
- Third-party authentication assistance for avatar usage
- Network storage for application-specific user data
- Multi-modal instruction transmission for real-time interaction
- Charging information collection for avatar-associated communications

Section 6.3.4: MPEG Avatar Representation Format

Corrections:
- Updated reference to ISO/IEC 23090-39 (ARF specification)
- Clarified ARF data model components
- Enhanced description of ARF container formats

Technical content maintained:
- ARF data model including skeletons, meshes, blendshapes, skins, landmarks, and nodes
- Support for ISOBMFF and Zip-based containers
- Integration with MPEG Scene Description (ISO/IEC 23090-14)
- Reference client architecture with Avatar pipeline in Media Access Function
- Ongoing exploration experiments for compression, geometry integration, animation formats, content discovery, and animation controllers

Section 7.1: General Architecture and Call Flows

Corrections:
- Removed leftover editorial brackets in text
- Clarified avatar function descriptions

Key architectural components:
- Avatar Storage: Base avatar storage with access control and authorization
- Avatar Animation: Retrieves base avatar and performs animation using format-specific data streams
- Scene Management: Creates and composes shared 3D scenes with avatar integration
- Animation Data Generation: Converts raw signals (camera, microphone, sensors) to animation data
- Base Avatar Generation: Creates base avatar from captured inputs

Workflow distribution:
- Multiple workflow examples showing different distributions of avatar functions between sending UE, network, and receiving UE
- Workflow selection depends on service requirements, UE capabilities, and network configuration

Impact Assessment

The CR addresses editorial errors and incorrect references that would otherwise remain in the specification. No functional changes are introduced, only corrections and clarifications to existing content.