Accurate and secure distance measurement is critical for Industrial Internet of Things (IIoT) environments. Its applications range from secure asset tracking, automated warehousing systems, building automation, and access control systems. However, ordinary ranging methods struggle to meet the high standards of precision and security demanded by modern IIoT applications.

The NXP MCX W72 wireless microcontroller (MCU) integrates Bluetooth Channel Sounding technology, supported by the FRDM-MCXW72 and MCXW72-LOC development boards, to address these challenges and facilitate rapid prototyping and deployment.

For years, Bluetooth ranging has relied on Received Signal Strength Indication (RSSI) and Angle of Arrival/Angle of Departure (AoA/AoD) technologies. While these methods are easy to implement, they suffer from limited accuracy and security vulnerabilities. For example, RSSI measurements are highly susceptible to environmental factors and multipath interference, and both methods are vulnerable to man-in-the-middle (MITM) attacks, where an attacker can spoof distance measurements by manipulating signal strength.

This shows how Bluetooth Channel Sounding technology combines Round Trip Time with phase-based ranging methods

Bluetooth Channel Sounding, part of the Bluetooth 6.0 standard, adopts a fundamentally different ranging approach, combining two complementary techniques: Round Trip Time (RTT) and Phase-Based Ranging (PBR). RTT provides secure, coarse distance estimation using encrypted, time-stamped packets that cannot be replicated by attackers. PBR then achieves fine-grained accuracy by measuring phase shifts in exchanged tones, typically achieving ±0.5 meter accuracy in open-air environments.

Channel Sounding builds a robust defense against relay and amplification attacks by using time-stamped encrypted packets and cross-validating RTT and PBR measurement results. This technology is ideal for applications that require precise and accurate distance measurements that directly impact safety, such as smart locks, access control systems, keyless vehicle entry, digital door locks for homes, and building automation systems.

Design an IoT project using advanced Bluetooth Channel Sounding and a positioning calculation engine. Order the FRDM-MCXW72 development board for your next project.

NXP MCX W72: Channel Sounding Solution for IIoT Applications

The MCX W72 is NXPs Bluetooth 6.0 Channel Sounding-certified wireless MCU, designed for IIoT applications. The platform supports multi-protocol connectivity, including Bluetooth Low Energy, Matter over Thread, and Zigbee.

MCX W72 Block Diagram

At the heart of the MCX W72s ranging capability is a dedicated Localization Calculation Engine (LCE). This dedicated hardware can accelerate localization algorithm operations up to 10 times faster than the main Arm® Cortex®-M33 core, reducing algorithm execution time by nearly 45%. The result is lower latency and reduced power consumption, which is critical for battery-powered IIoT devices.

The NXP MCX W72 ensures information security through its integrated EdgeLock® Secure Zone core profile, which can isolate sensitive cryptographic operations such as key storage and trusted boot processes. Additionally, its advanced Bluetooth Low Energy radio unit supports up to 24 simultaneous connections, providing robust connectivity for complex IIoT deployments where multiple devices need to communicate and coordinate ranging operations.

Hardware Support: Development Boards for Rapid Prototyping

To help developers apply Bluetooth Channel Sounding technology to real-world scenarios, NXP provides dedicated hardware platforms to accelerate prototyping. This series of development boards simplifies the evaluation process, accelerates time-to-market, and offers flexible options for building secure and precise ranging solutions.

FRDM-MCXW72 Development Platform

The FRDM-MCXW72 brings NXPs proven FRDM platform to wireless development. This cost-effective development board comes pre-loaded with a wireless demo that works immediately with the NXP IoT Toolbox mobile app, allowing developers to evaluate basic functions within minutes of unboxing. The board offers multiple expansion options, including Arduino headers, mikroBUS, and Peripheral Module (Pmod) connectors, making it easy to add sensors and peripherals for specific application prototyping. The onboard MCULink debugger based on the LPC55S69 also eliminates the need for external debug tools. Other features include external flash, an I²C sensor, an ambient light sensor, RGB and blue LEDs, CAN connectivity, a PCB antenna, and a uFL connector for conducted (cable) measurements.

MCXW72-LOC Localization Board

For developers specifically focused on Channel Sounding applications, the MCXW72-LOC provides a dedicated evaluation platform. This IIoT evaluation kit offers comprehensive testing capabilities for the MCX W72s multi-protocol wireless support, including Bluetooth Low Energy, Zigbee, Thread, Matter, and CAN connectivity.

The MCXW72-LOC employs a dual-antenna diversity system, dynamically selecting between two 2.4GHz antennas via an RF switch, improving ranging accuracy compared to the single antenna on the FRDM-MCXW72 board. By re-soldering capacitors, SMA connectors can be selected instead of the antennas to support conducted (cable) measurement experiments.

The MCXW72-LOC board comes pre-loaded with a Channel Sounding demo. Developers can pair two MCXW72-LOC boards to seamlessly demonstrate a wireless ranging session and evaluate performance under real-world conditions. The platform also features an advanced MCU-Link hardware debugger, multiple power and low-power options, dual CAN transceivers, buttons, switches, LEDs, and a MikroE Click connector for easy sensor integration.

Development Ecosystem Support

Both boards are fully compatible with the NXP development ecosystem. The MCUXpresso Software Development Kit (SDK) provides drivers, examples, and comprehensive documentation. Additionally, the Application Code Hub (ACH) offers expert-written code examples to accelerate development, while the Expansion Board Hub (EHB) bridges the gap between developers and compatible add-on boards from NXP and its ecosystem partners. NXPs proprietary algorithms convert raw Channel Sounding measurement data into precise distance estimates, abstracting the complex mathematics for application developers.

NXP KW47: Bringing Channel Sounding to Automotive Systems

KW47 Architecture

While the MCX W72 is primarily targeted at IIoT, NXPs KW47 brings the same Channel Sounding capabilities to automotive applications. As NXPs first automotive-grade Bluetooth 6.0 Channel Sounding MCU, the KW47 meets AEC-Q100 Grade 2 qualification and supports ASPICE, MISRA software standards, and AUTOSAR with integrated CAN communication.

The NXP KW47 enables secure digital key systems and automotive access applications, with an impressive detection range—capable of detecting a driver from up to 100 meters away and providing 20-50 cm accuracy at close range. The KW47 shares the same platform architecture as the MCX W72 (including the same LCE and EdgeLock security technology), ensuring a consistent development experience and interoperability across automotive and IIoT applications. The KW47-LOC development board also provides automotive developers with evaluation tools similar to the MCXW72-LOC for IIoT applications.

Solutions Now in Production

The NXP MCX W72 and KW47 are both in production. Development boards are now available, and developers can start prototyping immediately using these boards, preparing for mass production.Unlocking infinite possibilities.