Performance of High-Accuracy Phase-Based Ranging in Multipath Environments

Narrow-band radios, i.e. Bluetooth low-energy (BLE) or Zigbee, are widely available in smartphones or sensor networks. Distance estimation is a highly desired function, because it enables new kinds of services like asset tracking, commissioning of sensors and keyless entry systems. The current solution based on signal strength, does not offer enough accuracy to support these services. Phase-based ranging is much more accurate, but multipath fading is severely impacting the accuracy. In this work we propose three methods to improve the precision of the distance estimation using phase-based ranging. The first method is to calculate a one-way-channel-response from a two-way-channel response, the second method is to use a super-resolution algorithm to improve the separation of line-of-sight from non-line-of-sight components. And the third method is to use antenna polarization and to combine the data in an efficient way. We will support these proposed improvements with measurements in a multipath-rich environment.