TWPalo: Through-the-Wall Passive Localization of Moving Human with Wi-Fi

Abstract

Being essential for many emerging applications, the device-free localization systems have gained increasing interest, of which the through-the-wall device-free localization is of great challenge. This paper presents the design and implementation of TWPalo, a through-the-wall device-free localization system based on Wi-Fi channel state information (CSI). To this end, we first develop an algorithm for three dimensional joint estimation of angle of arrival (AoA), time of flight (ToF) and Doppler frequency shift (DFS). Combining with this algorithm, we then separate the CSI and obtain the parameters of each propagation path through the iteration of parameter estimation, channel reconstruction and cancellation. At last, the human induced reflection is found out and its relevant parameters are translated into the precise location of the human behind the wall. Our implementation and evaluation on commodity Wi-Fi devices demonstrate that TWPalo is better than existing systems in the form of AoA estimation and localization accuracy under the through-the-wall scenario.