# Summary of 3GPP TR 26.501 Change Request

## Document Information
- **Meeting**: 3GPP TSG-S4 Meeting #135, Goa, India (9-13 February 2026)
- **Document Number**: S4-260247
- **CR Type**: Category B (addition of feature)
- **Release**: Rel-20
- **Work Item**: FS_3DGS_MED (3D Gaussian Splatting Media Study)

## Main Purpose

This CR introduces high level media data workflows for **Client-Server configuration** in the context of 3D Gaussian Splatting (3DGS) service delivery. This complements the existing all-in-client configuration by defining workflows where functionality is split between the UE client and the network server.

## Technical Contributions

### New Clause 9.2: Client-Server Configuration

#### 9.2.1 Description
- Defines media data workflows where functionality is split between client and server (network)
- Supports **interactive navigation in large or dynamic 3DGS scenes**
- Enables network-assisted processing for resource-intensive operations

#### 9.2.2 Media Workflow Steps

##### 9.2.2.1 Workflow Description
The CR identifies the following workflow steps that execute in the Client-Server configuration:

**Server-Side Operations:**
- **3DGS Content Generation**: Generation of 3DGS content from 2D captures of scenes (references clause 5.2)
- **Dynamic Content Generation**: Creation of dynamic 3DGS content and region-based parts of 3DGS scenes based on the 3DGS model for adaptive delivery
- **Adaptive Selection**: Selection of 3D tiles and their Level of Detail (LOD) based on:
  - User movement
  - UE device capabilities
- **Packaging and Distribution**: 3DGS assets packaged in the network and delivered via:
  - MMS
  - OTT messaging
  - Download services

**Client-Side Operations:**
- **Content Reception**: UE receives one or more of:
  - 3DGS assets (clause 5.2)
  - 3D tiled LODs (clause 5.3)
  - Dynamic 3DGS scene content via file delivery, partial-delivery, or on-demand streaming (clause 5.4)
- **Storage**: Content stored in local memory or GPU memory
- **Rendering**: UE renders:
  - 3DGS assets by selecting Gaussians based on LODs dependent on:
    - User preferences
    - UE device capabilities and characteristics (camera pose, display resolution, etc.)
  - 3D tiled LODs fetched using adaptive delivery (clause 5.3)
  - 3D Avatars using time-aligned animation streams (clause 5.5)

##### 9.2.2.2 Characteristics
The CR defines key characteristics of the client-server configuration:

**Latency/Performance:**
- Dependent on network and application latency
- Influenced by:
  - Capabilities of the network server generating 3DGS content
  - UE device rendering capabilities

**Scalability:**
- **Enhanced scalability** compared to all-in-client configuration
- Leverages theoretically infinite network resources
- Enables more use cases

**Network Usage:**
- Content generation
- Rendering (full or partial)
- Distribution

**Network Interaction During Playback:**
- Selection of 3D tiles and LODs
- Sending user pose information
- Temporal updates
- Optional partial or full rendering support

## Affected Clauses
- **Clause 9.2**: New clause added for Client-Server configuration

## Relationship to Existing Work
This CR builds upon:
- Clause 5 use cases (referenced throughout)
- Clause 9.1 All-in-client configuration (complementary approach)
- Various delivery mechanisms already defined in the study (MMS, OTT messaging, file delivery, streaming)