RTT Measurement Approach
- An RTT range system requires an initiator to send an FTM request and a responder to respond to it with an acknowledgement (ACK). A complete callback will return four time points t1 ~ t4.
- The RTT is calculated from n groups of callbacks according to the equation
Test bed configuration
- Initiator Google Pixel 2: Android OS version ≥ 9.0 (Android Pie), with RTT process supported wireless card and chipset.
- Responder WILD fit2: 802.11 mc protocol supported. Can be configured to work in both 2.4 GHz and 5 GHz channels with channel bandwidths of 20 MHz, 40 MHz, 80 MHz.
RTT positioning result
- The average error of all these tests is 0.54 m, which is far more precise then all existing Wi-Fi fingerprinting and propagation model based methods (generally considered to be 1.5 ~ 2 m).