The Bluetooth Core 6.x specification family
Bluetooth Core 6.0 was adopted on 27 August 2024. Version 6.1 was adopted on 5 May 2025, 6.2 on 3 November 2025, and 6.3 on 5 May 2026. These are successive releases of one specification family rather than separate radio standards.
A specification number does not define the complete feature set of a device. A manufacturer may implement only some optional features, and use of a new mechanism usually requires compatible controller and host support at both ends of a connection.
The 6.x family mainly develops distance measurement, advertising packet filtering, address privacy, Bluetooth LE connection parameters, and the HCI interface. Individual mechanisms are negotiated and optional, so a release number does not describe one complete set of radio features.
Channel Sounding in Bluetooth Core 6.0
operates over an ACL connection and combines two measurement methods. Phase-Based Ranging uses phase changes in signals transmitted at multiple frequencies, while Round-Trip Timing determines the signal round-trip time between an initiator and a reflector. Either a Central or a Peripheral can take the Initiator or Reflector role.
PBR provides data for precise distance estimation. RTT also acts as a security check because it makes simple signal relaying less effective at reducing the measured distance. The specification defines security procedures and metrics used to detect possible measurement manipulation.
Core 6.0 defines 72 Channel Sounding channels, each 1 MHz wide, and a separate LE 2M 2BT PHY used by this procedure. RTT improves resistance to simple signal relaying, but it is not a standalone security guarantee.
Channel Sounding produces the distance between a pair of devices. Determining a two-dimensional or three-dimensional position requires several reference points, known installation geometry, and a positioning algorithm. Accuracy depends on hardware, measurement count, multipath propagation, and obstacles.
- A digital key can verify whether a device is sufficiently close to a lock.
- An item tag can provide an application with a better distance estimate than RSSI.
- An indoor positioning system can combine results from several fixed reference points.
Advertising filtering and device monitoring
Decision-Based Advertising Filtering allows the host to define conditions for evaluating advertising packets. The controller checks selected fields and forwards only matching packets to the host. This reduces HCI traffic and application-processor wake-ups.
The mechanism follows conditions configured by host software. It does not train a model, make predictions, or classify data autonomously. Describing it as an artificial intelligence feature would be inconsistent with the specification.
Monitoring Advertisers enables the controller to notify the host whether an observed device continues to transmit advertising packets. The host no longer needs to infer a timeout from a sequence of scanning reports.
Bluetooth Core 6.0 also extended the Link Layer feature set. The changes include ISOAL Enhancement, LL Extended Feature Set, and Frame Space Update. The last mechanism allows the spacing between selected ACL and CIS packets to be negotiated; before this change, the default spacing was 150 microseconds, while other transports retained fixed spacing. Changing the spacing can shorten a procedure or leave more processing time, depending on device capabilities.
Changes in Bluetooth Core 6.1
Bluetooth LE can use a to limit long-term tracking based on a fixed radio address. In earlier releases, address update timing was more predictable.
Bluetooth Core 6.1 introduced randomized RPA update timing. The controller selects an interval from a configured range instead of always changing the address after the same period. This makes consecutive addresses harder to correlate through a regular schedule.
The controller can perform a scheduled address update without requiring the host to plan each operation, reducing host involvement and energy use. Randomizing the update moment also lowers the chance that many devices handled by one hub perform the operation simultaneously.
Distributing updates over time also reduces cases in which many devices perform cryptographic operations and change addresses simultaneously. This matters for hubs handling many active Bluetooth LE devices.
Randomized timing does not provide anonymity against every tracking method. Traffic characteristics, application data, and device behavior may still permit correlation. RPA is one privacy mechanism, not a complete solution to the problem.
Shorter connection intervals in version 6.2
Before version 6.2, the baseline minimum Bluetooth LE connection interval was ms with a resolution of ms. Shorter Connection Intervals reduces the supported minimum to microseconds and introduces a microsecond resolution.
A shorter interval requires feature-support negotiation. New Link Layer procedures allow a peripheral to propose a parameter range, while the central selects a configuration that both sides can execute.
Both peers must report support for Shorter Connection Intervals. Link Layer procedures carry the proposal and parameter selection, so 375 microseconds is not an automatic setting for every device carrying a 6.2 version number.
More frequent connection events can shorten response time for HID devices, human-machine interfaces, and sensors. This does not unconditionally reduce complete application latency. Processing time, queues, and retransmissions also affect the result.
Bluetooth Core 6.2 also extended Channel Sounding protection with resilience to attacks based on amplitude manipulation. The procedure uses, among other elements, the Normalized Attack Detector Metric (NADM) and a Discrete Fourier Transform based analysis that looks for components characteristic of periodic amplitude changes in RTT packets.
Version 6.2 also includes HCI USB LE Isochronous Support with an optional Bulk Serialization Mode, as well as LE test-mode enhancements with the Unified Test Protocol and OTA testing. These controller and transport features depend on the implementation.
Bluetooth Core 6.3 refinements
Inline PCT Transfer changes how the phase correction term is handled in Channel Sounding. A reflector can correct phase while retransmitting a tone, so the initiator receives data that requires less subsequent processing.
The change reduces the amount of PCT data transferred over HCI and can accelerate a ranging procedure. It is a negotiated feature, so the traditional method remains available when either device does not support it.
PHY-specific RTT Accuracy allows RTT accuracy parameters to be declared separately for supported physical layers. A system can select the exchange count and radio mode according to the capabilities of a particular PHY instead of applying one declaration to every mode.
Version 6.3 expanded HCI command and event masks through the Running Out of Bits feature. The Supported Commands mask grew from 64 to 251 octets, and the LE Event Mask from 8 to 255 octets. Core 6.3 harmonized selected radio requirements and removed the deprecated Data Signing feature. These changes provide space for future interface functions.
What the version means for system design
The maximum LE 2M PHY symbol rate is Msym/s, corresponding to a raw rate of Mbit/s. LE 1M is the mandatory PHY and LE 2M is optional; the 2M 2BT variant serves Channel Sounding. The main 6.x changes concern measurement, control, and optimization procedures rather than one faster modulation for every device.
A design should verify support for the required feature instead of relying only on the Bluetooth version advertised for a chip. Relevant factors include controller and host versions, exposed HCI commands, profiles, product qualification, and peer compatibility.
Energy consumption, ranging accuracy, and latency cannot be derived from the specification number alone. These parameters require measurements for the specific hardware, antenna configuration, software, and radio environment.