What Is Bluetooth 6?
Bluetooth® 6 is the latest major revision to Bluetooth, which enables electronic devices at short range to wirelessly exchange data. Bluetooth 6 was announced in September 2024 by the Bluetooth Special Interest Group (SIG). Some salient features in Bluetooth 6 are:
- Channel Sounding, for accurate distance measurements
- Decision-based advertising filtering, for more efficient channel scanning
- Monitoring advertisers, for improved energy efficiency when devices come into and go out of range
- Interframe space updates, for both higher throughput and better coexistence management
According to the SIG, Bluetooth Channel Sounding enables more accurate distance awareness, 10 cm ranging accuracy, and enhanced security.
Ranging with Bluetooth Channel Sounding
Before Bluetooth 6, a received signal strength indicator (RSSI) measurement was used to infer the distance between two Bluetooth devices, assuming a free space path loss on the link. But if the signal suffered more loss from multipath or shadowing, the distance would be overestimated.
Bluetooth 6 introduces two ways to accurately measure distance:
- Round-trip time (RTT) measurement
- Phase-based ranging (PBR) measurement
RTT
The RTT measurement method in Bluetooth 6 uses the fact that the signal time of flight (TOF) between two devices is half the RTT. It can then accurately compute the distance d as
\(d=(\tfrac{RTT}{2})*c\)
where c is the speed of light. This method requires accurate measurements of the time of departure (TOD) of the outbound signal from device 1 (the initiator), time of arrival (TOA) of the outbound signal to device 2 (the reflector), TOD of the return signal from device 2, and TOA of the return signal to device 1. The diagram below shows the signal paths and the times. The time tI is the RTT of the initiator, and the time tR is the time from reception at the reflector to its subsequent transmission.
Measuring distance using round-trip time of flight between initiator and reflector.
PBR
The PBR method in Bluetooth 6 uses two signals of different frequencies to measure distance. These signals are simply tones—sine waves. The distance can be calculated as a function of the phase difference between the two received tones. Because a given phase difference value can hold true for an infinite number of distance values, the device supporting Bluetooth 6 selects the shortest distance that satisfies the phase difference condition. The expected range of PBR is about 150 m. Also, if three or more locator Bluetooth 6 nodes participate in RTT or PBR ranging, they can use trilateration to find the location of a device being tracked.
Bluetooth 6 outlines RTT and PBR distance measurement methods, but Channel Sounding does not mandate a specific algorithm for calculating distance estimates. This flexibility allows device manufacturers to tailor solutions to various use cases, balancing computational complexity with required accuracy and adapting to different radio environments.
Enhanced Security Measures in Bluetooth 6
Bluetooth 6 devices using Channel Sounding enjoy security from distance spoofing and man-in-the-middle attacks, for the following reasons:
- Bit patterns are randomized with a standard-specified deterministic random bit generator.
- Transmit power can be varied to reduce the received signal-to-noise ratio for attackers.
- Devices can deploy an attack detector system.
- RTT and PBR can be combined to provide redundant distance measurements and more easily detect spoofed results.
Other Bluetooth 6 security enhancements include:
- Use of the Advanced Encryption Standard (AES)
- Decision-based advertising filtering, which reduces unnecessary data transmissions and reduces exposure to unwanted listeners
- Use of Elliptic Curve Diffie-Hellman for secure key generation when pairing two devices
Bluetooth 6 Use Cases and Applications
Bluetooth 6 Channel Sounding can be used for:
- Keyless vehicle entry, performed by communication between a key fob or phone and the car’s anchor points
- Smart locks, to permit access only when an authorized device is within a designated proximity to the locks
- Geofencing, to limit access to designated areas
- Warehouse management, to monitor inventory and manage logistics
- Asset tracking for virtually any object of interest
Keyless entry
Smart locks
Geofencing
Warehouse mgmt.
Asset tracking
These use cases can support applications for smart home devices, medical devices, supply chain management, and logistics.
Bluetooth 6 with MATLAB
Channel Sounding
With MATLAB® and Bluetooth Toolbox, you can model ranging scenarios and estimate distances using the RTT and PBR methods of ranging specified in Bluetooth 6. You can specify any number of Bluetooth locator nodes and perform localization in 2D or 3D, using either RTT or PBR.
Visualizing the estimated and actual locations of a moving asset being tracked by locator nodes using RTT or PBR. (See MATLAB code.)
Interframe Spacing
You can also examine the effect of variable interframe spacing in Bluetooth 6 on throughput and latency in an asynchronous connection-oriented logical (ACL) connection. Additionally, you can configure the IFS in a connected isochronous stream (CIS).
Examples and How To
Software Reference
Bluetooth 6 FAQs
Bluetooth 6 is the latest major revision announced by the Bluetooth SIG, adding features like Channel Sounding, decision‑based advertising filtering, advertiser monitoring, and interframe space (IFS) updates to enhance accuracy, efficiency, and coexistence. These capabilities enable centimeter‑level ranging, lower latency, and improved energy efficiency in LE systems.
Bluetooth 6 unlocks applications such as real‑time location systems, smart factory automation, and enhanced security for connected devices. These capabilities go beyond traditional audio and data transfer, supporting advanced IoT and automation scenarios.
Channel Sounding replaces RSSI‑based proximity with two standards‑based ranging methods: round‑trip time (RTT) and phase‑based ranging (PBR). By measuring time of flight or phase differences across tones, devices can estimate distance with ~10 cm accuracy under appropriate conditions.
RTT computes distance from signal time of flight, requiring precise timestamps at initiator and reflector; PBR derives distance from phase differences of two tones, typically supporting ranges up to ~150 m. Combining RTT and PBR improves robustness and spoofing resistance.
Bluetooth 6 allows variable IFS in asynchronous connection-oriented (ACL) connections and connected isochronous stream (CIS) for LE Audio, enabling higher throughput or better coexistence depending on channel conditions. Engineers can tune IFS to balance latency and reliability across link‑layer scenarios.
Bluetooth 6 employs randomized bit patterns, adjustable transmit power, and attack detection mechanisms; combining RTT and PBR improves spoofing detection. The spec also highlights AES and Elliptic Curve Diffie-Hellman (ECDH) for secure key generation and pairing.
Decision‑based advertising filtering and advertiser monitoring reduce unnecessary transmissions and scanning overhead. These mechanisms help devices conserve energy while maintaining responsive discovery and connection behavior.
Bluetooth 6 introduces coexistence strategies for LE Audio and WLAN in 6 GHz, including configurable IFS and channel access mechanisms such as Listen Before Talk (LBT), Spectrum Sensing-Based Deferral (SSBD), and Detect and Avoid (DAA). These approaches help reduce interference and maintain link reliability.
Bluetooth 6 adds centimeter‑level ranging, improved coexistence, and energy‑efficient scanning, enabling use cases such as precise indoor positioning, industrial asset tracking, and secure proximity‑based access control.
Yes. MATLAB and Simulink, with Bluetooth Toolbox, provide workflows to model Bluetooth 6 features such as Channel Sounding (RTT/PBR), IFS behavior, LE Audio, and coexistence with WLAN. These simulations help engineers prototype and validate designs before hardware is available.
See also: Bluetooth Toolbox, Communications Toolbox, Bluetooth interference, Bluetooth mesh, wireless network, multi-object tracking, ultra-wideband (UWB), Bluetooth and MATLAB: A Winning Combination
