Inside Bluetooth Channel Sounding: The Next Step for Digital Keys
Exploring how Channel Sounding transforms Bluetooth into a secure spatial sensing platform, following my latest EETimes Asia article.
Introduction
Bluetooth technology is entering a new phase of precision and security. The introduction of Channel Sounding (CS) in the Bluetooth Core Specification 6.0 adds sub-meter, even centimeter-level distance measurement evolving Bluetooth from a communication protocol into a secure spatial sensing platform, setting the stage for digital keys, access control, and location-aware IoT applications at scale.
Precision through Phase and Time
Unlike traditional RSSI-based proximity or angle-of-arrival systems, Bluetooth CS measures how radio signals propagate across the channel, leveraging both Phase-Based Ranging (PBR) and Time-of-Flight (ToF) analysis.
The dual approach enables tens of centimeter-level accuracy while maintaining robust distance bounding security, a crucial defense against relay and spoofing attacks that have undermined earlier RSSI BLE keyless systems.
New Channel Sounding Core specifications: 6.2
Version 6.2 of the Bluetooth Core Specification enhances CS performance with:
・Anomaly detection, mitigating amplitude-based spoofing (introducing Discrete Fourier Transform).
・Shorter connection intervals (down to 0.375 ms), improving responsiveness for AR/VR and real-time control.
・Improved algorithms that reduce the dependence on multi-antenna hardware, lowering system cost.
For all details, read the full article on EETimes Asia
🔗 Secure Ranging with Bluetooth Channel Sounding: From Digital Keys to IoT Applications
Integration Pathways
From my perspective, Bluetooth CS can be deployed in two primary automotive configurations:
1. CS + In-Cabin Monitoring: hybrid setups combining BLE authentication with mmWave or UWB sensing.
2. Stand-Alone CS Systems: cost-sensitive implementations for keyless entry, wearables, and access control, where sensing remains only optional.
Competitive Landscape and Ecosystem
The technology is rapidly industrializing. Among the main chip vendors: Qualcomm, Nordic Semiconductor, NXP, Texas Instruments, Silicon Labs, Telink, Synaptics have all announced CS-capable SoCs.
Module vendors, u-blox, Ezurio, Murata among others, are offering pre-certified designs, while IP providers such as CEVA, IMEC, and Metirionic and OnceLabs supply the algorithms and simulation tools needed for precise phase measurement.
This ecosystem maturity positions Bluetooth CS as a practical alternative to UWB, particularly for OEMs seeking secure proximity without a major hardware redesign.
Market Overview
Technotrend Market Research forecasts that UWB-enabled vehicles will surpass 9 million units by 2025, with early adoption concentrated in premium and upper mid segments. Bluetooth CS, leveraging BLE’s near-universal presence in smartphones, offers a lower-cost entry point for car OEMs seeking to optimize BOM costs and enable broader adoption across mid-range vehicles and IoT devices.
Take a look into my article on EETimes Asia on Digital key
🔗 433MHz to Digital Keys: The Security Evolution of Vehicle Access
Because CS can often be enabled via OTA firmware updates on Bluetooth 5.3+ SoCs, it offers a cost-efficient path toward digital-key functionality and secure ranging, expanding beyond the automotive domain into smart locks, wearables, and industrial asset tracking.
The Takeaway
Bluetooth Channel Sounding extends BLE from a communication protocol into secure distance measurement, unlocking a new generation of spatially aware devices.
As the Bluetooth ecosystem matures, CS is poised to democratize precise, secure proximity detection, enabling mass-market deployment in connected vehicles.