BLE Channel Sounding: Novel Method for Enhanced Ranging Accuracy in Vehicle Access

The recent attempts for vehicle thefts using Relay Station or Man in Middle attacks have triggered the need for precise and secure distance measurement between the owner device and vehicle. Ultra-Wide Band offers high accuracy ranging; it is expensive and hence could not be deployed in vehicle access. Bluetooth (Register Trademark) Low Energy Channel Sounding is excellent cost effective and mass scale alternative for enhanced ranging and vehicle access solution. The motivation for this research work lies in minimising power consumption thereby maximising battery life for the handheld owner device such as keyfob or smartphone; whilst offering unparalleled security against Man in the Middle or Relay Station Attacks. The proposed work combines the conventional low power Received Signal Strength Indicator based approach with the Bluetooth (Register Trademark) Low Energy Channel Sounding framework for accurate distance estimation. The coarse ranging offered by conventional Received Signal Strength Indicator approach is embedded into proximity based secure pairing as well as a pre-check before establishing connection between paired devices. The proposed work performs bidirectional measurement of values of Received Signal Strength Indicator, Phase Based Ranging and Round-Trip Time and cross-correlation of them to enhance accuracy using novel method. The development process utilized ANSYS HFSS 3D High Frequency Simulation for dual antenna design, enabling precise phase difference calibration. The implementation was achieved using a chipset with an ARM Cortex M33 core, hardware accelerators, and a BLE Channel Sounding stack integrated through a Software Development Kit. This work demonstrates a practical, scalable, and secure solution for BLE-based ranging in modern vehicle access systems. Besides security, proposed work provides opportunities for many more use cases such as distance based welcome feature where vehicle will recognise approaching owner and welcome with step by step turning ON of functions such as approach light, ambient light, unlocking the doors etc. The experimental results demonstrate that the proposed method achieves ranging accuracy comparable to existing LF and RF technologies.