An electronic device includes an indoor positioner and a positioning engine server. The indoor positioner has an antenna array including a plurality of antenna units. The indoor positioner divides the antenna units into multiple antenna unit groups, receives a wireless signal from user equipment at each time point via the antenna unit groups, and calculates a plurality of angles of arrival (AOA) corresponding to the antenna unit groups at each time point. The positioning engine server receives and stores the angles of arrival corresponding to the antenna unit groups at each time point, and filters the angles of arrival according to the angle sizes of the angles of arrival corresponding to the antenna unit groups at each time point stored in an observation period.