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What Developers Need to Know About Bluetooth® Core Spec 5.3

Telink Staff

September 24, 2021


Woman with bluetooth earbud

The new Bluetooth® Core Specification 5.3 redefines what is possible in wireless communication, with major improvements to wireless reliability, energy efficiency, and user experience.

The Bluetooth® Special Interest Group (SIG) is constantly driving technological innovation. This continuous evolution has allowed Bluetooth to meet the growing demand for wireless communication across countless use cases for more than 20 years. 

As a global wireless standard for IoT, Bluetooth’s Core Specification is a key factor in the development of Bluetooth-enabled device interoperability. Over the years, updates to the Bluetooth Core Specification have included enhancements to existing features and the introduction of major new features to reflect significant technological advancements and pave the way for new possibilities in wireless innovation.

On July 13, 2021, Bluetooth SIG released version 5.3 of the Bluetooth Core Specification. The new key features provide IoT device makers and application developers with increased reliability, better energy efficiency, and enhanced user experience.

New key features of Bluetooth 5.3

Periodic Advertising Enhancement

Bluetooth 5.3 introduces an AdvDataInfo (ADI) field that will indicate whether the payload data has been changed in any of the periodic advertising packets, thus enabling more efficient processing of redundant data.

Bluetooth broadcast devices, like many Bluetooth Low Energy (LE) products, often transmit multiple copies of the same data in rapid succession to increase the probability the data is received. With the AdvDataInfo field in packets sent via Periodic Advertising, receiving devices can now recognize redundant data and discard it immediately in the controller rather than pass it up to the host. This new process increases overall Bluetooth network efficiency by saving processing capacity and reducing node power consumption.

Encryption Key Size Control Enhancements

With increased demand for security in IoT applications, Bluetooth 5.3 enhances the encryption key control between the Host and Controller to prevent hacking and security attacks. These Host Controller Interface (HCI) enhancements improve signaling efficiency in many Bluetooth Classic products, as all Bluetooth BR/EDR connections already use or encourage encryption.

The new Host to Controller encryption key control enhancements enables the Host to specify the minimum key size that the Controller will accept when establishing a connection to another device. This also provides developers with better flexibility to address various application needs using the Host to Controller connection. 

The HCI already had the capability to inform the Host when encryption settings on an existing connection have been changed. Now, with the enhancements, it automatically includes the key size of the changed connection, thus improving signaling efficiency.

Connection Subrating

Connection Subrating minimizes delay during connection parameter updates. Not only does it deliver a better end-user experience, but it also retains the power-saving properties of low duty cycle connections. By enabling rapid switching between low and high duty cycles, the Connection Subrating feature on Bluetooth 5.3 implements a more efficient transition procedure to reduce the transition delay, thereby significantly improving device functionality and user experience.

Connection subrating can be found in smart medical devices and Bluetooth LE audio products, as they operate in a low-power monitoring state to maximize battery life. A Bluetooth hearing aid, for example, will stay in low duty cycle until the user receives a phone call or plays music on their smartphone. At that time, the hearing aid will then quickly transition to support a higher duty cycle. 

Channel Classification Enhancement

How channel classification works in Bluetooth 5.3

Bluetooth 5.3’s new channel classification feature allows peripheral devices to provide connected central devices with radio channel classification data. Connection reliability and throughput are improved with reduced sensitivity to inference at the peripheral device when the peripheral and central devices are not in close physical proximity.

When Bluetooth-enabled devices are connected, a spread spectrum technique called adaptive frequency hopping (AFH) is used. Bluetooth technology divides the 2.4GHz (ISM) frequency band into smaller channels and rapidly hops between those channels when transmitting packets. A channel selection algorithm chooses the channels while a table of data called the channel map classifies each channel as either used (suitable for use) or unused (not suitable for use). Prior to the 5.3 update, Bluetooth LE channel classification was performed only by the central device and saw many instances of packet collisions and overall degraded throughput. However, as now both peripheral and central devices may perform channel classification, the reduced likelihood of packet collisions will lead to better throughput and reliability.

Telink and the New Specification

Telink’s TLSR9 chip can support the new Bluetooth Core Spec 5.3 features, providing developers the enhanced reliability and energy efficiency they need to improve end-user experience. The SDK will be released in the future and customers can choose to upgrade their product via OTA or start the new design with the 5.3 SDK.

Please visit our wiki to learn more about all our development tools, or ask us a question through our Technical Forum or by contacting us directly today.