Stereo Bluetooth HFP Encoding With 2-EV5 Packets for Higher Throughput

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Solution Overview

Problem

Existing Bluetooth communication protocols, such as the Hands-Free Profile (HFP), are limited to monophonic audio transmission, which restricts data throughput and audio quality, especially for high-fidelity applications, and cannot support stereo audio transmission effectively.

Innovation Solution

Modifying the mono HFP protocol to utilize the 2-EV5 transport packets with larger packet sizes and longer duty cycles, along with the Advanced Audio Coding-Enhanced Low Delay (AAC-ELD) codec, to enable bi-directional stereo operation for wideband, super wideband, and full-band audio, allowing for tripled data throughput and support for redundant packets for error correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If monophonic audio transmission is used in Bluetooth HFP protocol, then processing complexity and latency are reduced, but data throughput and audio quality are limited

Engineering Contradiction:
Improveaudio processing complexityVSAvoiddata throughput
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent segments the audio transmission into separate channels (left and right) while maintaining the monophonic processing structure in each channel. This allows stereo audio transmission without requiring complete redesign of the processing architecture, thus improving throughput while controlling complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from monophonic (1D audio signal) to stereo (2D audio signal with separate left and right channels) transmission. This dimensional change enables higher data throughput and improved audio quality while maintaining compatible processing methods

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Device complexity

If monophonic audio transmission is used in Bluetooth HFP protocol, then processing complexity and latency are reduced, but audio quality is compromised

Engineering Contradiction:
Improveaudio processing complexityVSAvoidaudio quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent segments the audio transmission into separate channels (left and right) while maintaining the monophonic processing structure in each channel. This allows stereo audio transmission without requiring complete redesign of the processing architecture, thus improving throughput while controlling complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from monophonic (1D audio signal) to stereo (2D audio signal with separate left and right channels) transmission. This dimensional change enables higher data throughput and improved audio quality while maintaining compatible processing methods

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If stereo audio transmission is implemented, then audio quality is enhanced, but data throughput requirements increase

Engineering Contradiction:
Improveaudio qualityVSAvoiddata throughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent segments the audio transmission into separate channels (left and right) while maintaining the monophonic processing structure in each channel. This allows stereo audio transmission without requiring complete redesign of the processing architecture, thus improving throughput while controlling complexity

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the packet size parameter from the standard 60 bytes to 360 bytes for 2-EV5 transport packets. This parameter change enables tripled data throughput capacity, providing sufficient bandwidth for high-quality stereo audio transmission while maintaining protocol compatibility

Inventive Principle:
Principle #35Parameter changes

4Productivity

If larger packet sizes are used for stereo audio, then data throughput is tripled, but packet duration increases

Engineering Contradiction:
Improvedata throughputVSAvoidpacket duration
Core Design Contradiction:
ProductivityVSDuration of action of moving object

Solution Approach 1:

The patent dynamically adjusts the packet duration to 15 ms for 2-EV5 transport packets, which is longer than the standard 7.5 ms but optimized for stereo audio transmission. This dynamic adjustment enables tripled throughput while the extended duration provides sufficient time for complete audio frame transmission and processing

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS12488803B2Method and system for encoding and wirelessly transmitting stereo audio content for audio communication
Publication Date: 2025.12.02 APPLE INC
  • US12488803B2 patent drawing
  • US12488803B2 patent drawing
  • US12488803B2 patent drawing

AI summary

Disclosed are systems and methods to modify the Bluetooth mono HFP protocol to support bi-directional stereo operation for high bandwidth audio including 12-KHz wide-band, 16-KHz super wide-band (SWB), and 24-KHz full band (FB) audio. The techniques leverage the larger packet size and longer duty cycle of the 2-EV5 transport packet and expand the block size of the audio frames generated by the AAC-ELD codec to increase the maximum data throughput from the 64 kbps of the mono HFP protocol to 192 kbps using a stereo HFP protocol. The increased throughput not only supports stereo operations, but allows the transport of redundant or FEC packets for increased robustness against packet loss. In one aspect, the AAC-ELD codec may be configured for dynamic bit rate switching to flexibly perform trade-offs between audio quality and robustness against packet loss. The stereo HFP may configure the maximum throughput based on the desired audio quality.