Bluetooth® low energy channel sounding in a compact and energy-efficient radio transceiver
Abstract
Bluetooth® Low Energy (LE) Channel Sounding (CS) is a new physical-layer capability that enables accurate characterization of the radio channel for distance estimation. CS uses structured packets exchanged between two devices to extract phase and timing information. These measurements support two complementary techniques: Phase-Based Ranging (PBR), which derives distance from multi-frequency phase observations, and Round-Trip Time (RTT) estimation, which infers propagation delay from precisely timestamped packet exchanges. Both approaches require tight control of RF timing, antenna switching, sampling, and calibration. We implemented the CS feature set on a 22 nm Bluetooth® LE radio, integrating the required waveform generation, sampling pipelines, and protocol scheduling into the existing baseband architecture. The implementation exposes the extensive programmability defined by the specification, including configurable parameters, such as data-rates, antenna switching patterns, processing delays, etc. This flexibility enables detailed experimentation with ranging algorithms and channel-estimation techniques while highlighting the complexity of coordinating physical-layer operations at microsecond-scale precision. The resulting platform provides a robust foundation for evaluating CS performance and exploring advanced localization and sensing applications.
Publication Reference
CSEM Scientific and Technical Report 2025, p. 11–12
Year
2025