# LS on Traffic Model for Immersive Communication

## Document Information

- **Source:** Huawei Hisilicon (SA WG4 to be)
- **To:** RAN WG1
- **Response to:** R1-2509596/S4-260013
- **Release:** Rel-20
- **Work Item:** FS_6G_MED

## Overall Description

SA4 provides a response to RAN1's LS regarding traffic models for immersive communications, drawing on previous study work and ongoing investigations.

## Main Technical Contributions

### Historical Context from 5G Studies

#### TR 26.955 - 5G Video Codec Study

- **Immersive Gaming Scenarios (Clause 7.3.3):**
  - Evaluated rate points between **20 Mbit to 100 Mbit** for highest quality sequences
  - Target scenario: **4K + HDR at 120 fps**
  - No values above 100 Mbit reported in the study
  
- **Frame Rate Considerations (Table 6.6.3.7-1):**
  - Frame rates of **90 fps and 120 fps** considered for online gaming
  - Aligns with proposed model updates from RAN1

- **Industry Deployment Reference:**
  - Current gaming services (e.g., GeForce Now) require approximately **50 Mbit+**

- **5G Uplink Limitations:**
  - High quality uplink scenario (4K + HDR) was **not considered** due to limited uplink bandwidth
  - SA4 developed coding profiles for downlink applications (5G media streaming, immersive gaming)

### Uplink Scenario Considerations

#### Real-Time Uplink Characteristics

- **Encoder Constraints:**
  - Uplink encoders (sender side) typically less powerful than downlink
  - Expected values in the **higher range** of 20-100 Mbit for transparent quality
  
- **Adaptive Mechanisms:**
  - Temporary frame rate drops and/or quality switches may compensate for encoder limitations
  - Could still result in comparable bit-rates
  
- **Traffic Variability:**
  - Frame rate changes more likely compared to traditional downlink cases
  - Bit-rates in **20-100 Mbit range** assumed for transparent quality

### 3D and Immersive Formats

#### TR 26.956 - Emerging 3D Formats

- **Clause 9 Results:**
  - Explored formats beyond traditional 2D video:
    - Video-based point cloud
    - Multi-view stereo with depth
    - Immersive video
  
- **Bit-rate Range:**
  - Transparent quality results roughly in **20-100 Mbit range**
  - Matches RAN WG1 assumptions
  
- **Frame Rate Limitation:**
  - Only lower frame rates tested: **25-30 fps**

#### Ongoing Studies

- **Gaussian Splat-Based Imaging:**
  - Currently under study in SA4
  - Could result in:
    - Different frame rates
    - Potentially **(much) larger bit-rates**

### Future Work in FS_6G_MED

- Study just started in SA4
- Uplink video scenario **not yet studied**
- Expected investigation areas:
  - High quality uplink cases based on SA WG1 use cases
  - Derivation of corresponding requirements for uplink video
  - Building on earlier 5G downlink results

## Actions

**To RAN WG1:**

SA4 respectfully requests RAN WG1 to take this information into account.

## Key Technical Takeaways

1. **Bit-rate Range Alignment:** SA4's previous studies support the 20-100 Mbit range proposed by RAN1 for immersive communications
2. **Uplink-Downlink Asymmetry:** Uplink scenarios expected to require higher bit-rates within the range due to encoder constraints
3. **Format Evolution:** Emerging 3D formats (point clouds, Gaussian splats) may require significantly higher bit-rates than traditional 2D video
4. **Frame Rate Considerations:** High frame rates (90-120 fps) already considered in 5G studies, with adaptive mechanisms expected in uplink scenarios