Bluetooth® 5.3 – What‘s New for IoT Device Makers and Application Developers?

PublishTime： 2021-08-19 Article Source：Silicon Labs

Bluetooth^® 5.3, the latest release of one of the world's most popular wireless IoT technologies, was published July 13th, 2021. This blog explains what's new on Bluetooth 5.3 for IoT device makers and application developers.

What's Bluetooth 5.3?

Bluetooth 5.3 is the latest version of one of the world's most deployed wireless IoT connectivity technologies. Bluetooth Low Energy is enabled widely in IoT devices across all sectors and applications. The market update 2021, published by the Bluetooth Special Interest Group (SIG), estimates that there will be a total of 13 billion Bluetooth IoT devices in use in 2021. What makes Bluetooth the go-to wireless technology for IoT device makers and application developers? It is the ubiquitous support and global interoperability on digital devices of all kinds and types!

Bluetooth IoT Growth

Bluetooth SIG estimates that the Bluetooth Low Energy single-mode device shipments are forecasted to more than triple (3X) over the next five years, until 2025. A rapidly growing technology platform, such as Bluetooth, needs to evolve constantly to stay relevant and fuel the ecosystem's growth. The new Bluetooth 5.3 version was released to ensure just this – a continued global growth!

New Features in Bluetooth 5.3

The Bluetooth 5.3 release adds several feature enhancements which provide IoT device makers and application developers with significant reliability, energy efficiency, and user experience improvements. The following sections give an overview of four top enhancements in Bluetooth 5.3:

Connection Sub-rating

Image caption: Bluetooth 5.3 Enhanced Connection Update feature.

A smart blood glucose meter is an ideal example of a peripheral Bluetooth device, which primarily operates in a low-power monitoring state without transmitting high-throughput data. During this time, the device maintains a low duty-cycle mode to maximize battery life. When it needs to send a data burst to the central device, e.g., trigger an insulin dose, the device must first transition to a higher duty-cycle mode. This transition can take a long time because of how the connection update procedure has been implemented.

The Connection Sub-rating feature on Bluetooth 5.3 makes slow connection updates a thing of the past. It implements a more efficient transition procedure to reduce the transition delay. Connection sub-rating switches between low and high duty cycle modes in a new, faster way and handles variable packet rates and bursty traffic more efficiently.

In applications such as smart medical devices, faster transition times can significantly improve device functionality, user experience, and safety. With the Connection Sub-rating, Bluetooth devices can now return to an energy-efficient mode earlier, after high data transmission, to extend battery life even further.

Encryption Key Size Control Enhancements

Robust security is becoming an ever more critical end-user requirement in IoT applications such as access control, door locks, portable medical devices, and commercial lighting. Bluetooth 5.3 now responds to the market need and enhances the encryption key control between the Host and Controller to protect IoT devices and applications and their users against hacking and security attacks.

The new Host to Controller encryption key control enhancements allows the Host to set a minimum encryption key length that the Controller can accept. The Host is more application-aware and hence, is in the best position to decide the key length based on the application's security requirements. It allows controlling the encryption key size via the stack, providing developers higher flexibility for addressing various application needs using the Host to Controller connection. Multiple host stack–link-layer interactions are avoided while quicker re-connections can support delay-sensitive use cases such as human interface devices.

Periodic Advertising Enhancement

Image caption: The Bluetooth 5.3 AdvDataInfo in Periodic Advertising feature.

Currently, all periodic advertisements must be reported to the Host. However, in some cases, when there are no changes in the advertisement data, this can result in unnecessary processing on the nodes. It can reduce overall throughput. With this new Bluetooth 5.3 feature, an AdvDataInfo (ADI) field is introduced in periodic advertising. The ADI field in the packet header indicates whether the payload data has been changed in any of the periodic advertising packets. In the event there are no changes, the node can drop the subsequent packets in the chain and use the time to process other receive transactions.

The ADI in periodic advertising increases overall Bluetooth network efficiency, saves processing capacity on the nodes, reduces node power consumption, and gives more time for scanning in primary channels.

Channel Classification Enhancements

Image caption: How the channel classification works in Bluetooth 5.3.

Sometimes the central and peripheral devices participating in a Bluetooth connection can experience interference of different magnitudes, originating from various sources. Imagine the difference in interference experienced by a vibration sensor (peripheral device) attached to an industrial rotating machine vs. the smartphone (central device) carried by the condition monitoring staff. Before Bluetooth 5.3, only the central device could decide the channel map without any information on how the peripheral device experiences the channel conditions. This can reduce wireless reliability in many business-critical use-cases in situations as described above.

The new channel classification feature on Bluetooth 5.3 enables the peripheral device to inform the central device of the desired channel map based on the experienced RF conditions. The central can then take an appropriate decision to arrive at an optimal channel map. The channel classification enhancement can improve the overall wireless performance, especially when the devices are transmitting at +10 dBm as ETSI does not allow transmission above +10 dBm on channels with interference.

Bluetooth 5.3 Conclusions

As an IoT device maker or application developer, you know that the competition in the IoT market is tough – every inch counts when it comes to winning the customers' hearts. The Bluetooth 5.3 release is a minor enhancement to the protocol. Yet, it provides major improvements on wireless reliability, energy efficiency, and user experience, enabling you to create ever more innovative ways to win the IoT race!

Learn more about Silicon Labs' broad Bluetooth offering for IoT – including the Bluetooth Low Energy SDK, Bluetooth chips (SoC and module hardware), and security with the world's first PSA Level 3 security certified hardware.

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