# Summary of S4-260141: Target Platforms for ULBC

## 1. Introduction and Motivation

This contribution addresses a gap in TR 26.940 regarding target platforms for Ultra Low Bit rate Codec (ULBC) deployment. While the TR currently discusses NPU as a possible platform in clause 6.2.1.5.1, it lacks coverage of other non-NPU platforms. The document aims to complete this missing information, particularly focusing on DSP-enabled devices.

## 2. Technical Problem Statement

The contribution identifies an inconsistency in TR 26.940:

- **Clause 6.2.1.1** states that the codec must support real-time processing alongside other audio processing units and should fit real-time resource constraints of CPUs, potential accelerators, and **DSPs** across a range of devices
- **Clause 6.2.1.5.1** currently only describes NPU as a target platform, omitting DSP and other non-NPU platforms

The source references previous contributions (S4aA250267 and S4-251747) that discussed the need for DSP deployment and provided clarification on DSP-enabled UE devices.

## 3. DSP-Enabled Device Definition

The contribution adopts the definition from S4-251747 for DSP-enabled UE devices:

- **Devices with DSP only** or **devices with multiple computing units including DSP**
- For multi-unit devices (with CPU/NPU/DSP), there remains a preference for DSP deployment due to:
  - Lower power consumption
  - Reduced heat generation
  - Better battery life
- Target devices include vehicle-mounted devices, glasses, and mobile phones with low computational capability
- DSP refers to audio processing DSPs available in mobile phones or other devices for voice communication

## 4. Proposed Text Changes

### Main Technical Contribution

The proposal adds a new paragraph to clause 6.2.1.5.1 that:

1. **Acknowledges vendor flexibility**: Vendors may choose any computing unit to implement ULBC based on business needs or product constraints

2. **Highlights DSP advantages**:
   - Cheaper in terms of silicon real estate
   - Less power hungry
   - Less heat generation
   - Typically single-threaded for synchronized real-time execution with low overhead
   - Potentially wider range of product support

3. **Establishes DSP deployment requirement**: ULBC should be deployable on DSP-enabled UE devices, including:
   - Devices with DSP only
   - Devices with multiple computing units including DSP

4. **Provides deployment rationale**: Even when CPU or NPU are available, DSP may be preferred for power-sensitive applications (wearables, mobile phones)

5. **Defines DSP computational power**: Audio processing DSPs typically range from **several hundred to over a thousand MIPS**

### Context Preservation

The proposal maintains the existing text about:
- NPU prevalence in modern smartphones
- NPU being 5-20x more power efficient than CPUs for AI tasks
- The note that ULBC may need to run on non-NPU platforms in certain configurations

## 5. Technical Impact

This contribution ensures that TR 26.940 provides comprehensive guidance on target platforms for ULBC deployment, balancing the AI-optimized NPU approach with the power-efficient DSP approach, thereby supporting a wider range of device implementations and use cases.