Group Delay Calibration for Wi-Fi Ranging Based on 802.11az/mc

Wi-Fi ranging concerns estimating the distance between two Wi-Fi devices and this has applications such as proximity detection in door locks, indoor navigation, self-locating access points, etc. The presentation begins with a brief overview of Wi-Fi ranging based on the 802.11mc Fine Timing Measurements (FTM) and 802.11az HE Ranging NDP frames. For Wi-Fi ranging purposes, it is often taken for granted that the delays within the WI-Fi radio are somehow calibrated out. This presentation highlights the need for accurate group delay calibration of the Wi-Fi radio in order to get good ranging accuracy. It delves deeper into the various factors that affect the group delay of the radio including the group delay of baseband and RF filters, amplifiers, mixers, DAC/ADC blocks and highlights the need for proper delay compensation mechanisms at a per part level, without which it will be difficult to achieve the desired ranging accuracy in production.