Bluetooth 5.3 new features lower latency, interference, improve battery life, security

Bluetooth 5.3 Core Specification was adopted on July 13, 2021, without fanfare, and the only related announcement that I could find is CEVA RivieraWaves Bluetooth IP getting support for Bluetooth 5.3.

Bluetooth 5.3 brings four new features or enhancements and removes one extension from the core specification:

Periodic Advertising Enhancement – The AdvDataInfo (ADI) field of the common extended advertising payload format may now be included in AUX_SYNC_IND protocol data units (PDUs) which are broadcast when a device is performing periodic advertising. The Bluetooth Low Energy (LE) controllers may now use the information in the ADI field to recognize packets that contain retransmitted copies of identical or semantically equivalent data, and discard those packets in order to prevent unnecessary processing on the nodes, and make sure the overall throughput is not affected due to retransmitted packets.

Encryption Key Size Control Enhancement – In Bluetooth BR/EDR, encryption key sizes are negotiated by the controllers in connected devices. This change allows a host to inform its Bluetooth BR/EDR controller of the minimum acceptable key size using the Host Controller Interface (HCI). This enhancement also improves the efficiency with which Bluetooth BR/EDR controllers can inform the host of the outcome of key length negotiations. IoT applications such as access control, door locks, portable medical devices, and commercial lighting will particularly benefit from the new feature.
Connection Subrating – Some product types spend much of their time in a low-duty cycle connection so that power is conserved. But when higher bandwidth is needed to support a particular application use case, the connection parameters must be changed as quickly as possible.
Source: Silabs

Connection Subrating allows connection parameter updates to be made with minimal delay, delivering a better user experience but at the same time, retaining the power-saving properties of low duty cycle connections. This can be especially useful in smart medical devices such as a smart blood glucose meter.
Channel Classification Enhancement – Bluetooth LE Peripheral devices are now able to provide a connected Central device with radio channel classification data which may be used by the Central device when performing channel selection during adaptive frequency hopping.
Source: Silabs

This improves throughput and reliability by reducing susceptibility to interference taking place at the Peripheral when the Peripheral and Central devices are not physically close to each other. One example would be a vibration sensor (peripheral device) attached to an industrial rotating machine and the smartphone (central device) carried by the condition monitoring staff which experience interference of different magnitudes and from different sources.
Removal of the Alternate MAC and PHY (AMP) Extension – The Alternate Media Access Control and Physical layer extension (aka AMP) allows a Bluetooth system to include one or more secondary controllers alongside a primary Bluetooth BR/EDR controller. This extension is seldom found in qualified Bluetooth products, so the Bluetooth SIG has removed this feature from the Bluetooth Core Specification version 5.3. It will still be possible to qualify products that use AMP against an earlier Bluetooth Core Specification version.

You’ll find more details about Bluetooth 5.3 features on the specification page, as well as a blog post on Silicon Labs.

Thanks to Andreas for the tip

Jean-Luc Aufranc (CNXSoft)

Jean-Luc started CNX Software in 2010 as a part-time endeavor, before quitting his job as a software engineering manager, and starting to write daily news, and reviews full time later in 2011.