Bluetooth Channel Sounding is a new feature introduced in Bluetooth 6.0 that enhances distance ranging capabilities. It builds upon Bluetooth Low Energy’s (LE) established use in device positioning and location services. Channel Sounding enables secure and precise distance measurement between devices, opening possibilities for innovative applications, especially in mobile phones and battery-powered devices.
The technology behind Channel Sounding relies on two primary techniques: Phase-Based Ranging (PBR) and Round-Trip Timing (RTT). PBR calculates distances by analysing phase differences of signals across multiple frequencies, while RTT measures the time taken for a signal to travel between devices and back. These methods ensure secure and accurate distance measurements, with the algorithms for conversion handled at the application level.
Channel Sounding complements existing Bluetooth features, such as the Find Me Profile, RSSI-based proximity detection and Direction Finding introduced in Bluetooth 5.1, which enabled angle calculations using signal phase measurements.
This feature is expected to enhance numerous applications. For example, it can improve the reliability of beacons by providing accurate proximity alerts, even in challenging conditions. Smart locks will benefit from improved presence detection and enhanced security against relay attacks. Appliances can use the technology for user-centric contextualisation, such as enabling functions only when the user is nearby. Additionally, asset tracking may become more precise and reliable without significant increases in cost or complexity. Bluetooth 6.0’s Channel Sounding feature is designed to achieve distance measurement accuracy within ±10 centimetres. In early test implementations, accuracy levels of ±20 centimetres have been observed.
The adoption of Bluetooth Channel Sounding, like previous advancements such as Mesh, Direction Finding and Angle of Arrival (AoA), is expected to face very long delays in concrete implementation relative to the release of the standard. Also, historically, the adoption of newer Bluetooth LE enhancements has been relatively slow, with limited uptake across the industry. This is due to the requirement for new devices and updated software that leverages new Software Development Kits (SDKs), making the technology complex to develop and deploy. Also, compatibility constraints often mean that new Bluetooth LE features can’t be retrofitted to existing devices.
For those looking to measure distance effectively today, a practical alternative is to use beacons like the iBS03R, which incorporates Time of Flight (TOF) distance sensing as a dedicated hardware sensor. This approach offers immediate, reliable and actually more accurate (25mm rather than 20cm) distance measurement, albeit over a shorter (3m) distance, without waiting for the broader implementation of Channel Sounding in the market.