Bringing Bluetooth 6.0 Channel Sounding to Market
Victor Lee, Sr. FAE
2025 tech talks WEBINAR SERIES
[Bluetooth Logo]
Agenda
- Technology Overview
- Channel Sounding Applications
- Silicon Labs Offerings
- Algorithm Performance Data
- Developer Tools
- Q&A
Why Bluetooth® Channel Sounding?
The Challenge:
- IoT applications need 'spatial' awareness to be more secure, reliable, and responsive
- Earlier Bluetooth LE versions lack native support for precise ranging
- [RSSI] based ranging is noisy and unreliable in real-world use
- [Direction Finding] needs complex antennas, adding cost & complexity
The Opportunity: Channel Sounding for Bluetooth
- Standardized approach for accurate, secure ranging in Bluetooth 6.0
- Enables sub-meter accuracy with robust performance, even in NLOS
- Works with single or dual antenna setups - flexible for different form factors
Comparison with UWB
UWB is accurate but often too costly, and bulky for IoT. Channel Sounding is more cost-efficient than UWB; requires minimal external components.
Built on existing Bluetooth infrastructure, simplifying adoption and ecosystem integration.
Visual description: Image depicting a dog wearing a tracking collar, a smartphone showing a location pin, and cars with location indicators, illustrating pet tracking and spatial awareness applications.
Bluetooth® Channel Sounding Overview
Measure distance between two devices using
- Phase-based Ranging (PBR)
- Round Trip Time (RTT)
- RTT and PBR operates across 2.4 GHz band
- Standard specifies up to 72 channels
- Random channel hopping pattern
Connection-Oriented 2-way ranging with two roles
- Initiator: device that wishes to calculate distance from itself to another device
- Reflector: device responding to initiator
- Supports up to 4 antenna paths between devices (8 possible antenna combinations)
- Multiple security features included in the standard
- Can be combined with Angle of Arrival / Departure (AoA/AoD)
- Enables position estimation with single locator/tag pair
Additional Resources
- Webpage - Learn more about Silicon Labs offerings and demos
- Tech Talk - Explore Bluetooth Channel Sounding
- Workswith 2024 - Enable Accurate Distance Estimation Using Channel Sounding
- Blog: Learn more about Antenna Switching with Silicon Labs Channel Sounding
- API Spec: Getting Started with Silicon Labs Bluetooth Channel Sounding
Bluetooth® Channel Sounding Comparison
| Localization metric | Antenna requirements | Connectivity | Performance metrics | Solution advantages | Solution disadvantages |
|---|---|---|---|---|---|
| RSSI | Single antenna | Connection-oriented and connectionless | +/- 5 m, high susceptibility to multipath interference | Ubiquitous support for RSSI measurements in existing Bluetooth LE products | Highly susceptible to RF noise and multipath |
| UWB | Often complex hardware | Connectionless | High accuracy (~10–30 cm) | • High Precision • Low Latency |
Expensive and complex integration |
| Angle of Arrival | Multi-antenna required by spec | Connection-oriented and connectionless | +- 3 degrees accuracy – azimuth +- 5 degrees accuracy – elevation |
• Scalable solution for real time position tracking • Supports 5-10 year battery life |
Needs complex antenna setup and calibration |
| Channel Sounding | Single or dual antenna | Connection-oriented | +- .3 m < 5m with PBR +- 0.5 m > 5m with PBR |
• Small form factor with flexible antenna design • Feature-add for security by proximity |
Scalability |
Bluetooth® Channel Sounding - Target Markets & Use Cases
Proximity Awareness
- Door locks
- Keyless entry
- Building access systems
- Geofencing - security alerts
Localization
- Indoor asset management - hospitals, warehouses
- Pet tracking
- Item finding - wallet, keys
Automapping
- Solar Trackers
- Luminaires, Access Points
- Accurate Mapping for Battery Storage
Visual description: Diagrams illustrating proximity awareness around a building, indoor asset tracking in a warehouse, and a network of access points (AP0-AP3) for automapping.
BG24: Optimized for Battery Powered, Channel Sounding-enabled IoT Devices
Visual description: Image of the Silicon Labs BG24 chip.
Differentiated Features
- Ultra small form-factor (3.1 x 3.0 WLCSP package)
- +20 dBm output power (Eliminates need for external power amplify)
- AI/ML accelerator (Accelerates inferencing while reducing power consumption)
- Secure Vault High (Protects data and device from local and remote attacks)
- 20-bit ADC (16-bit ENOB for advance sensing)
- Improved Coexistence (Ideal for gateways and hubs)
- PLFRCO (Eliminates need for 32 KHz xtal)
Device Specifications
- High Performance Radio (Up to +19.5 dBm TX, -97.6 dBm RX @ BLE 1 Mbps)
- Efficient ARM® Cortex®-M33 (Up to 78 MHz, 1536kB Flash, 256kB RAM)
- Low Power (49.1 μA/MHz (CoreMark), 5.0 mA TX @ 0 dBm, 5.1 mA RX (802.15.4), 4.4 mA RX (BLE 1 Mbps), 1.3 μA EM2 sleep)
- Multiple protocol support (Bluetooth 6.0 (1M/2M/LR), Bluetooth mesh, Proprietary 2.4 GHz)
Available in 5x5 QFN40 (26 GPIO), AEC-Q100; 6x6 QFN48 (32 GPIO), AEC-Q100; and 3.1x3.0 WLCSP42.
BG24L: Channel Sounding Optimized, High-Performance & Low-Cost AI/ML Wireless SoC
Visual description: Image of the Silicon Labs BG24L chip.
Differentiated Features
- Supports Bluetooth 6.0 (Channel Sounding optimized BLE SoC, Single-connection two-way ranging, Ideal Solution for Channel Sounding tags)
- Lowest Power RF (Increases battery life)
- PLFRCO (Eliminates need for 32 KHz XTAL and lowers overall system cost)
- 16-bit ADC (Up to 14-bit ENOB for better analog sensing)
- AI/ML accelerator (Accelerates inferencing while reducing power consumption)
- Secure Vault Mid (Protects data and device from local and remote attacks)
- Improved Coexistence (Ideal for gateways and hubs)
Device Specifications
- High Performance Radio (Up to +10 dBm TX, -97.6 dBm RX @ BLE 1 Mbps)
- Efficient ARM® Cortex®-M33 (Up to 78 MHz, 768kB Flash, 96kB RAM)
- Low Power (49.1 μA/MHz (CoreMark), 5.0 mA TX @ 0 dBm, 5.1 mA RX (802.15.4), 4.4 mA RX (BLE 1 Mbps), 1.3 μA EM2 (16kB RAM retention))
- Wide Operating Range (1.71 to 3.8 volts, +125°C operating temperature)
- Multiple protocol support (Bluetooth 6.0 (1M/2M/LR), Bluetooth mesh, Proprietary 2.4 GHz)
Available in 5x5 QFN40 (26 GPIO).
Bluetooth® Channel Sounding Dual Antenna Development Kit
Visual description: Image of the Silicon Labs xG24 Channel Sounding Development Kit board.
xG24 Channel Sounding Development Kit Features
- Available since March 2025
- Development Kit with two PCB antennas
- Antenna diversity offers increased robustness and accuracy
- Intra-event antenna switching for optimal non-line of sight performance
- Includes IMU sensor to detect movement & wake-up the tag
- Small form factor (Ideal for size-constrained applications like key fobs)
- AEC-Q100 Compliant
- SoC/NCP Sample Apps (Initiator and Reflector examples supported)
- Ranging Library (Process IQ samples, post-filtering, and compute distance using configurable algorithm)
Antenna Diversity – What does it bring?
Visual description: Comparison of ranging accuracy with different antenna path counts. 1 Path: 6.1 m, 2 Paths: 6.7 m, 4 Paths: 4.5 m. Graphs show signal strength over time for each path count. The actual distance is stated as 5 meters.
Silicon Labs Channel Sounding Algorithm
Algorithm Features
- Supports Multiple Channel Sounding Ranging Modes (PBR, RTT, PBR with RTT as sub mode)
- Antenna Switching (Built-in support for antenna diversity, Supports 1, 2 and 4 antenna paths)
- Supported Algorithm modes:
- Static mode – Delivers the highest accuracy with high measurement latency; optimized for ranging between stationary devices
- Real Time Basic – Provides high accuracy with increased computational and measurement latency; supports tracking at speeds up to 1 m/s
- Real Time Fast - Balances moderate accuracy and range with low latency; supports tracking at speeds up to 2.1 m/s, additionally produces velocity metric
- Configurable Channel Selection (72, 37, or 20 Channels) (Selectable based on accuracy needs and power constraints)
Key Benefits
- Licensing cost free (Eliminates third-party royalties, simplifying BOM cost structure)
- Optimized HW-SW Co-Design (Tight coupling between silicon & firmware ensures seamless performance & efficiency)
- Single-Vendor Lifecycle Support (Unified hardware & software ownership streamlines debugging, validation, and updates)
Algorithm Performance Test Setup
Visual description: A floor plan diagram shows the layout of a test environment with various locations marked for static and mobile EFR devices. A table details the test setup:
| Node Pairs | Distance (in m) | Obstacles |
|---|---|---|
| H & 1 | 20 | Line-of-Sight |
| H & 4 | 7.9 | Walls, Kitchen |
| 1 & 4 | 14.84 | Cubicles, Luminaires |
| 1 & 5 | 33.9 | Walls, Glass door |
Visual description: Photograph of a test setup with devices mounted on a rail.
Algorithm Performance Data
| Algorithm Mode | LOS 90th Pct. Absolute Error (in m) | LOS 95th Pct. Absolute Error (in m) | NLOS 90th Pct. Absolute Error (in m) | NLOS 95th Pct. Absolute Error (in m) | Computation time (in ms) |
|---|---|---|---|---|---|
| STATIC_HIGH_ACCURACY | 0.5 | 0.6 | 1.7 | 2.7 | 20000 |
| REAL_TIME_BASIC | 0.5 | 0.6 | 1.9 | 4.2 | 188 |
| REAL_TIME_FAST | 0.4 | 0.5 | 4.0 | 5.3 | 20 |
1 CS mode - PBR, CS channels – 72, number of antenna paths – 4
2 ~100 CS Procedures used to produce single distance estimate
Fit For Purpose Algorithm Modes
Energy Consumption Profile – Reflector
| Reference Board | Number of Antenna Paths (NAP) | Number of Channels | Mean Current Consumption (mA) | Mean Energy Consumption (nAh) |
|---|---|---|---|---|
| BRD2606A | 4 | 72 | ~2.2 | ~191.0 |
| 37 | ~1.2 | ~111.0 | ||
| 20 | ~0.9 | ~75.4 | ||
| 2 | 72 | ~1.7 | ~146.0 | |
| 37 | ~1.0 | ~91.0 | ||
| 20 | ~0.8 | ~65.0 | ||
| 1 | 72 | ~1.5 | ~122.8 | |
| 37 | ~1.0 | ~79.0 | ||
| 20 | ~0.7 | ~58.0 |
Antenna Diversity Increases Total Energy Per Measurement
Algorithm Performance
Algorithm Performance
Visualizer Tool
Visual description: Screenshots of the Visualizer Tool software interface, showing various real-time data plots and configuration options. The tool displays CS data, RSSI-based distance, raw and filtered distance estimates, and IQ data.
Visualizer Tool displays real-time CS data
- CS configuration
- Channel map selection
- Antenna path configuration
- Algorithm mode selection
- CS data visualization
- RSSI based distance for comparison
- Raw distance estimate and likeliness
- Filtered distance estimate
- IQ data visualization
- Interfaces with CS enabled EVKs
Silicon Labs Bluetooth® Channel Sounding Offering
Visual description: Diagram of the Bluetooth 6.0 stack architecture, showing layers from Application down to Bluetooth Link Layer. Other sections highlight CS & Development Kits, RTL Library, and SDK & Tools.
CS & Development Kits
- Channel Sounding Supported by B/MG24 Kits:
- xG24-RB4198A single antenna kit
- xG24-DK2606A dual antenna kit
Bluetooth 6.0 Stack
- In-house developed stack, supported and maintained stack
- Bluetooth 6.0 qualified
- PBR & RTT Modes
RTL Library
- Computes distance from raw I/Q data
- Developed and supported by Silicon Labs
- New features added based on market needs
- No 3rd party license fees
SDK & Tools
- Initiator & Reflector examples
- Real-time visualization tool for Bluetooth Channel Sounding
- Energy Profiler etc.
EFR32xG24 Channel Sounding Dev Kit attached to drone
Visual description: Image showing the EFR32xG24 Channel Sounding Development Kit attached to a drone in an outdoor setting.
Thank you
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