  As positioning solutions integrate multiple components to improve accuracy,
the number of parameters that require calibration has increased. This paper
studies a calibration-free positioning technique using Wi-Fi ranging and
pedestrian dead reckoning (PDR), where every parameter in the system is
optimized in real-time. This significantly decreases the time and effort
required to perform manual calibration procedures and enables the positioning
solution to achieve robust performance in various situations. Additionally,
this paper studies an efficient way of performing irregular Wi-Fi ranging
procedures to improve battery life and network performance of mobile devices.
The positioning performance of the proposed method was verified using a
real-time Android application on several mobile devices under a large indoor
office environment. Without any calibration, the proposed method achieved up to
1.38 m average positioning accuracy for received signal strength (RSS)-based
ranging scenarios, which differs only by 30 cm from the benchmark assuming
perfect calibration. In addition, the proposed method achieved up to 1.04 m
accuracy for round trip time (RTT)-based ranging scenarios with a 40 MHz
bandwidth configuration, which differs only by 10 cm from the benchmark.
