LE Audio is a complete audio architecture built on BLE, replacing Classic Audio profiles (A2DP, HFP). It uses the LC3 (Low Complexity Communication Codec) which delivers better quality than SBC at 50% lower bitrate. It supports stereo streaming to independent earbuds, multi-stream audio, and Auracast broadcast. LE Audio runs over BLE's power-efficient transport.

Connected Isochronous Stream (CIS): point-to-point audio over a BLE connection. Used for personal audio (earbuds, hearing aids). Provides acknowledged retransmission for reliability. Broadcast Isochronous Stream (BIS): one-to-many audio without connection. Used for Auracast (venue audio). No retransmission, but periodic advertising ensures sync.

Enhanced ATT allows multiple parallel L2CAP channels for GATT operations. Classic ATT is sequential: one request must complete before the next. EATT enables concurrent read/write operations, reducing latency for complex profiles like audio control. It also supports flow control credits for congestion management.

Wireless Protocols

Bluetooth 5.2

Bluetooth 5.2 (released December 2019) is the foundation for LE Audio, introducing isochronous channels (CIS for connected, BIS for broadcast) for time-synchronized audio streaming, the LC3 codec (better quality than SBC at 50% lower bitrate), Enhanced ATT (EATT) for parallel GATT operations, and LE Power Control for dynamic TX power adjustment. These features enable Auracast broadcast audio, true wireless stereo earbuds with independent streams, and hearing aid support.

Category: Wireless Protocols

Released: December 2019

Understanding Bluetooth 5.2

LE Audio replaces the Classic Bluetooth audio stack (A2DP/HFP/AVRCP over BR/EDR) with an all-BLE solution. LC3 delivers perceptually transparent audio at 160 kbps stereo (vs SBC at 345 kbps), saving battery in earbuds. Isochronous channels guarantee time-bounded delivery for audio frames, unlike ACL connections which are best-effort.

LE Power Control enables the receiver to request TX power adjustments from the transmitter, optimizing the link for power efficiency and interference reduction. Both devices converge on the minimum TX power needed for reliable communication.

LE Audio Efficiency

LC3 vs SBC (equivalent quality):
LC3: 160 kbps stereo
SBC: 345 kbps stereo
Bitrate savings: 54%

LE Power Control range:
−127 to +20 dBm (0.5 dB steps)

Bluetooth 5.2 Feature Summary

Feature	Purpose	Replaces
CIS	Connected audio (earbuds)	A2DP/HFP
BIS	Broadcast audio (Auracast)	None (new)
LC3	Audio codec	SBC/AAC
EATT	Parallel GATT	Sequential ATT
LE Power Control	Dynamic TX power	Fixed TX

Common Questions

Frequently Asked Questions

What is LE Audio?

Complete BLE audio stack with LC3 codec. Better quality at 50% lower bitrate vs SBC. Replaces Classic A2DP/HFP. Enables Auracast.

CIS vs BIS?

CIS: connected point-to-point (earbuds), with retransmission. BIS: broadcast one-to-many (Auracast), no connection needed.

What is EATT?

Enhanced ATT: parallel GATT operations over multiple L2CAP channels. Reduces latency for complex audio control profiles.

Related Terms

← Bluetooth 5.1 Bluetooth 5.3 →

LE Audio

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