The need for meter level location accuracy is driving increased adoption of 802.11 mc/az Fine Time Measurement (FTM) based ranging in Wi-Fi networks. In this paper, we present a comparative study of the ranging accuracy of 802.11mc and 802.11az protocols. We examine by real world measurements the critical parameters that influence the accuracy of FTM {\it{viz.,}} channel width, interference, radio environment, and offset calibration. The measurements demonstrate that meter-level ranging accuracy can be consistently attained in line of sight environment on 80 MHz and 160 MHz channels, while an accuracy of about 5m is obtained in non-line of sight environment. It is observed that the 802.11az protocol is capable of providing better accuracy than 802.11mc even in a multipath heavy environment.

翻译：对米级定位精度的需求正推动基于802.11mc/az精细时间测量（FTM）的测距技术在Wi-Fi网络中的广泛应用。本文对802.11mc与802.11az协议的测距精度进行了对比研究。通过实际测量，我们考察了影响FTM精度的关键参数，包括信道宽度、干扰、无线电环境以及偏移校准。测量结果表明，在80 MHz和160 MHz信道的视距环境中可稳定实现米级测距精度，而在非视距环境中精度约为5米。研究发现，即使在多径严重的环境中，802.11az协议仍能提供优于802.11mc的精度。