It is exciting to actually make 802.11mc FTM working with Intel 8260 chip! Greatly thank Mohamed Ibrahim for all the help!
Please find below the GitHub Wiki link for details to enable this feature on Intel 8260 chip:
https://github.com/HappyZ/iw_intel8260_localization/wiki/Enable-802.11mc-FTM-on-Intel-8260
Google recently announced Android P that supports 802.11mc. But note that since FTM requires hardware support that can do timing at picoseconds level, normal smartphones will not be able to achieve the same accuracy as they were presenting. Even with the Intel 8260 chip, since it is not calibrated in hardware, we cannot achieve cm-level accuracy. However, it can already achieve very good results in line-of-sight scenarios outdoor. At 10s of meters distance, we are able to achieve sub-meter level accuracy in ranging, and sub-meter level localization when we use multiple AP stations.
FYI, the best part of 802.11mc is AP and your smartphone do not need to connect to each other in the network domain. Everything is passive in a sense that if you turn on this feature, everyone will be happy 🙂