Accurate estimation of the angle of arrival (AOA) of the signal provides the possibility of high precision indoor positioning

in order to achieve the accurate AOA and extract the AOA information of the direct path to locate the target

this paper presents a sub-meter indoor localization system that uses the channel frequency response (CFR) to expand the array antenna.Firstly

this paper collects the CFR information to estimate the AOA and time of arrival (TOA) of Wi-Fi signal.Secondly

this paper presents a direct path identification algorithm based on the two-dimensional clustering information of AOA and TOA.In addition

this paper proposes a line of sight (LOS) environment and non line of sight (NLOS) environment recognition algorithm to distinguish whether the current receiver is in the LOS or NLOS environment relative the transmitter.Finally

this paper uses the existing Wi-Fi devices with three antennas to measure the angle and positioning in the indoor room.The experimental results show that the proposed positioning system can achieve a median error of 0.8 m and 1.3 m respectively in the LOS and NLOS environment

and can be used for high precision indoor positioning.