Silicon Labs introduces Bluetooth channel sounding

This new technology allows for secure, sub-metre precision in distance measurement between two Bluetooth-connected devices.

Bluetooth Channel Sounding is designed to provide enhanced distance awareness by improving the accuracy and security of device ranging. It represents a step change in location awareness, which has become increasingly critical in modern applications.

Ross Sabolcik, Senior Vice President of the Industrial and Commercial Business Unit at Silicon Labs, commented: “In a world where location awareness is critical, Bluetooth Channel Sounding revolutionizes proximity and location capabilities, propelling Bluetooth technology into a new era," said Ross Sabolcik, Senior Vice President of the Industrial and Commercial Business Unit at Silicon Labs. "With a legacy of empowering developers with the full potential of Bluetooth technology, Silicon Labs' latest hardware and software create an accelerated path to groundbreaking Bluetooth products equipped with Bluetooth Channel Sounding.”

Improving accuracy and security

Traditional Bluetooth distance estimation methods, such as the Received Signal Strength Indicator (RSSI), have facilitated new applications in device location and digital security. However, RSSI relies on estimations, which are susceptible to inaccuracies caused by multipath interference and obstructions. Bluetooth Channel Sounding overcomes these limitations, delivering sub-metre accuracy and enhanced security in distance estimation.

This technology utilises Phase-Based Ranging (PBR) to calculate precise distances, along with a secondary method, Round Trip Time (RTT), for cross-verification. By combining these techniques, Bluetooth Channel Sounding can detect anomalies, ensuring high security in applications such as hospital access control or geofencing in industrial facilities.

The practical applications of this technology span a wide range of industries. In home and lifestyle settings, it enables smart locks, pet tracking, and the location of consumer devices. For commercial use, it enhances vehicle keyless entry, access control, and geofencing. The technology’s ability to triangulate the position of commercial infrastructure, such as wireless access points, is particularly valuable for meeting regulatory requirements or reducing operational costs.

Bluetooth Channel Sounding is compatible with existing Bluetooth LE applications, offering an easy upgrade path without the need for additional hardware or design space.

xG24 platform supports channel sounding

Silicon Labs has introduced the xG24 Radio Board and Pro Kit, which are available for order and provide a comprehensive solution for developing Bluetooth Channel Sounding-enabled products. These kits include key components like the BRD4198A EFR32xG24 2.4GHz Radio Board and reference designs, making it easier for developers to prototype and create products with precise distance measurement capabilities.

In December 2024, Silicon Labs will release the xG24 Dev Kit, featuring a dual antenna PCB design and a Channel Sounding visualiser tool. This tool enables developers to view real-time distance measurements, simplifying the integration of Bluetooth Channel Sounding into their applications.

Silicon Labs offers a variety of hardware solutions tailored to different use cases:

• Single antenna hardware: Suitable for basic Bluetooth Channel Sounding applications, where simplicity and low power consumption are priorities. It offers reliable performance in environments where precise distance measurement is not critical.
• Dual antenna hardware: Available in December 2024, this solution provides higher accuracy and better spatial resolution, making it ideal for advanced applications requiring precise distance measurements, such as key fobs and tags. Its small form factor is especially suited to space-constrained designs.

All xG24 hardware is AEC-Q100 qualified, making it a suitable option for automotive applications such as Passive Entry and Passive Start systems.

Bluetooth Core Specification 6.0 and future developments

By the end of 2024, Silicon Labs expects to qualify the xG24 platform to version 6.0 of the Bluetooth Core Specification. This will introduce intra-event antenna switching for optimal performance in non-line-of-sight scenarios. The platform will support Bluetooth Channel Sounding whether the xG24 is used in Network Co-Processor (NCP) mode with an external application MCU or in System on Chip (SoC) mode with an integrated MCU.

Getting started with Bluetooth channel sounding

Silicon Labs provides a complete set of tools and resources for developers interested in Bluetooth Channel Sounding. This includes hardware solutions, software support, and a patent-pending distance estimation algorithm, enabling the creation of innovative products across various sectors such as home, industrial, commercial, and connected health.