# Summary of S4-260259: Application Scenario for Peer to Application (P2A) with Split Rendering

## Document Overview

This Change Request introduces a new application scenario for the Study on QUIC-based media delivery for real-time communication (RTC) services. The contribution focuses on defining the Peer to Application (P2A) scenario with split rendering as specified in TS 26.506 and TS 26.565.

## Main Technical Contributions

### 1. References Update

The document adds a new normative reference:

- **3GPP TR 22.870**: "Study on 6G Use Cases and Service Requirements" - This reference provides the foundation for the interactive application scenarios described in the contribution.

### 2. New Application Scenario: Real-time Interactive Applications with Split Rendering

#### 2.1 Architecture and Functional Split

The contribution defines a **split rendering architecture** where:

- **Peer Device Functions**:
  - User interaction capture
  - Local sensing
  - Final presentation
  - Acquisition of user inputs and contextual information (motion, pose, audio, video, spatial/environmental data, sensor information)
  - Transmission of captured data to application server

- **Application Server Functions**:
  - XR/gaming scene updates
  - Processing of received inputs
  - Application logic execution
  - Physics simulations
  - AI-based processing
  - Scene rendering
  - Transmission of rendered frames (2D video) and additional media (audio, haptics) to peer device

#### 2.2 Communication Characteristics

The scenario requires:

- **Bidirectional communication path** maintained throughout the session
- **Critical performance requirements**: End-to-end latency, jitter, and reliability
- **Security requirements**: Secure connections and encryption for privacy of sensitive data
- **Multi-modal stream support**: Audio, video, 2D/3D graphics, haptic feedback

#### 2.3 Deployment Scenarios

Two operational modes are defined:

- **Single-user scenario**: Application server receives pose, sensor updates, and video from device camera, updates scene in real-time, and sends rendered media back
- **Multi-user scenario**: Shared application state (virtual scene, digital objects, avatars) maintained at application server and consistently synchronized between server and all peers in real-time

#### 2.4 Network and Resource Requirements

The contribution identifies specific network support needs:

- **Differentiated connectivity** for interactive services
- **Low-latency and high-reliability communication** for multi-modal streams
- **Coordination** between communication, computing, and rendering resources
- Support for **dynamic offloading** of compute-intensive and rendering functions due to device constraints (form factor, energy consumption, rendering capabilities)

#### 2.5 Applicable Use Cases from TR 22.870

The contribution maps the P2A split rendering scenario to three specific use cases from TR 22.870:

1. **Immersive gaming (clause 9.2)**: Real-time immersive gaming and XR with multi-modal inputs, remote compute-intensive rendering and AI processing, requiring secured low-latency bidirectional media delivery

2. **XR rendering offload support (clause 9.4)**: Lightweight XR devices offloading rendering and processing to edge/cloud servers, requiring real-time exchange of user inputs and rendered media with tight latency constraints and network-assisted optimization

3. **Mixed reality gaming (clause 9.9)**: Multiplayer MR gaming with synchronized virtual scene based on common spatial map, continuous upload of environmental data to cloud server, real-time scene updates distribution to all participants under varying mobility and network conditions

## Technical Significance

This contribution establishes a foundational application scenario for evaluating QUIC-based media delivery protocols in the context of split rendering services. It clearly defines the functional split, communication requirements, and maps to existing 6G use case requirements, providing a concrete basis for protocol evaluation and optimization work in the study item.