High-resolution indoor positioning system using SDR modules

In this work, the problem of estimating the time difference of arrival (TDOA) associated with wideband orthogonal multi-carrier signals in multipath communication channels has been investigated using a single transmitter and a number of receiving base stations (BSs). Each BS has its own RF front-end including the local oscillator, filters, mixers, amplifiers, etc. Consequently, a precise estimation of time delays is not possible. Therefore, a technique to fully synchronize the BSs should be implemented. Using external reference to provide the clock frequency and sample time is not enough for a perfectly synchronized network. The phase uncertainties should be aligned by calibrating the estimated TDOAs. The software defined radio (SDR) modules are used to build a real system to measure the performance of the proposed wireless indoor positioning system using IEEE 802.11ac system parameters. Results show that an accuracy in the range of 3 cm can be achieved for 2 D wireless indoor positioning by using 20 MHz bandwidth.