Bluetooth LE Audio Control Signaling via Marked CRC Fields
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Solution Overview
Problem
Existing Bluetooth Low Energy Audio (LE Audio) systems face challenges in transmitting time-critical control data with low latency, leading to potential audio artefacts and delayed processing in hearing devices, such as hearing aids, due to the limitations of the Bluetooth protocol in handling control data efficiently.
Innovation Solution
Modifying the CRC field of the Broadcast Isochronous Group Control Protocol Data Unit (BIG Control PDU) to indicate the presence of time-critical control data, allowing for low-latency transmission without compromising audio signal integrity by using a marked or customized CRC value that can be recognized by compatible receiver units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If control data is transmitted using standard Bluetooth LE Audio protocols, then compatibility is maintained, but transmission latency increases and time-critical control data cannot be delivered quickly enough
Solution Approach 1:
The patent modifies the CRC field parameter in BIG Control PDUs to serve dual purposes: maintaining standard protocol structure for compatibility while embedding time-critical control data. By changing the interpretation and content of the CRC field from purely error-checking to including control information, the system achieves low-latency control data transmission without requiring a completely new protocol, thus resolving the contradiction between speed and compatibility
2Productivity
If audio packets are replaced with control data packets, then control data transmission is enabled, but audio signal integrity is compromised and audio artefacts occur
Solution Approach 1:
The patent segments the control data transmission by inserting control information into the CRC field of BIG Control PDUs rather than replacing entire audio packets. This segmentation allows control data to be transmitted within the existing audio stream structure without disrupting the audio packet flow, maintaining audio signal integrity while enabling efficient control data transmission
Solution Approach 2:
The CRC field serves as an intermediary structure that carries both its original error-checking function and additional control data. This intermediary approach allows the system to transmit control data without directly replacing audio packets, thus preventing audio artefacts while maintaining control data transmission efficiency
3Loss of time
If a modified CRC field is used to indicate control data, then low-latency transmission is achieved, but compatibility with standard receivers may be affected
Solution Approach 1:
The patent modifies the CRC field parameter to embed control data while maintaining the same field structure and position in the BIG Control PDU. Standard receivers continue to process the packet structure as expected, while compatible receivers can interpret the modified CRC field content to extract control data, thus achieving low-latency transmission without completely sacrificing compatibility
4Loss of time
If Voice Activity Detection control data is transmitted quickly, then hearing device processing is timely, but audio packet transmission may be disrupted
Solution Approach 1:
The patent applies local quality by modifying only the CRC field portion of the BIG Control PDU to carry control data, while leaving the rest of the audio packet structure intact. This localized modification enables fast VAD control data transmission without disrupting the overall audio packet transmission flow, ensuring both timeliness and reliability
Data Source
AI summary
There is provided a method for transmitting audio signals, comprising: establishing a wireless link utilizing Bluetooth LE Audio between an audio signal transmission unit and an audio signal receiver unit; transmitting BIS data PDUs representative of an audio signal via the wireless link from the audio signal transmission unit to the audio signal receiver unit; and providing, by the audio signal transmission unit, a BIG control PDU with time-critical control data to be transmitted to the audio signal receiver unit as part of its payload, wherein a marked CRC value is provided in the standard CRC field of said BIG control PDU which is different from the standard CRC value of said BIG control PDU.