What is Connection Subrating?

Connection Subrating allows a device to dynamically switch between fast and slow connection intervals without renegotiating parameters. A 'subrated' connection uses every Nth event. Example: base CI=15 ms, subrate factor=20 gives effective 300 ms interval during idle, instantly reverting to 15 ms when data arrives. Combines fast response with low idle power.

What is AdvDataInfo in periodic advertising?

AdvDataInfo (ADI) in periodic advertising enables the scanner to determine if the periodic advertising data has changed without decoding the full payload. If the ADI is the same as previously received, the scanner can skip processing, saving CPU and power. Essential for battery-powered receivers monitoring periodic trains.

Wireless Protocols

Bluetooth 5.3

Q: Channel Classification Enhancement?

Allows the peripheral (not just the central) to contribute channel quality information to the channel map. In BLE 5.2 and earlier, only the central classified channels. In 5.3, both sides share classification data, enabling faster and more accurate AFH (Adaptive Frequency Hopping) updates, improving coexistence with Wi-Fi.

Bluetooth 5.3 (released July 2021) focuses on efficiency, reliability, and coexistence. Connection Subrating enables dynamic CI scaling between fast (15 ms) and slow (300+ ms) without renegotiation. Channel Classification Enhancement lets both central and peripheral contribute to AFH channel maps. AdvDataInfo in periodic advertising enables scanners to skip unchanged payloads. Encryption Key Size Control allows applications to enforce minimum key sizes for security compliance.

Category: Wireless Protocols

Released: July 2021

Understanding Bluetooth 5.3

Connection Subrating is the headline feature. Previously, switching from a slow CI (for power savings) to a fast CI (for responsiveness) required a connection parameter update procedure taking ~100 ms. With subrating, the device pre-negotiates a subrate factor and can instantly switch between subrated (slow) and unsubrated (fast) operation, eliminating the update latency.

Channel Classification Enhancement improves coexistence in dense 2.4 GHz environments. When both devices contribute channel quality data, bad channels are identified and excluded faster, reducing retransmissions near active Wi-Fi APs.

Connection Subrating

Base CI: 15 ms (fast response)
Subrate factor: 20
Subrated CI: 15 × 20 = 300 ms (idle)

Switch time: <1 ms (instant)
vs ~100 ms for parameter update in 5.2

Bluetooth 5.x Evolution

Version	Year	Key Feature	Focus
5.0	2016	2M/Coded PHY, Ext Adv	Speed, Range
5.1	2019	Direction Finding (AoA/AoD)	Positioning
5.2	2019	LE Audio, LC3, Isochronous	Audio
5.3	2021	Connection Subrating	Efficiency
5.4	2023	PAwR, Encrypted Advertising	IoT Scale

Common Questions

Frequently Asked Questions

Connection Subrating?

Pre-negotiate fast/slow CI. Switch instantly (<1 ms). Base CI=15 ms, factor=20: idle at 300 ms, fast at 15 ms on demand.

Channel Classification?

Both central and peripheral contribute channel quality. Faster AFH updates. Better Wi-Fi coexistence in dense environments.

AdvDataInfo?

Scanner detects unchanged periodic advertising payloads without full decode. Saves CPU and battery on monitoring devices.

Related Terms

← Bluetooth 5.2 Bluetooth Mesh →