Location beacon database and server, method of building location beacon database, and location based service using same

A Wi-Fi location server system comprises a collection of information in a database describing Wi-Fi access points for at least one target area, including identification information for a corresponding Wi-Fi access point and calculated position information for the corresponding Wi-Fi access point, wherein calculated position information is obtained from recording readings of the Wi-Fi access point at various locations so that the calculation of the position of the Wi-Fi access point reduces arterial bias in the calculated position information; computer-implemented logic for receiving scan data including readings for Wi-Fi access points in the target area and associated locations at which the readings were detected; computer-implemented logic for identifying a potential error in the location information, including logic to identify the potential error using clustering techniques; and computer-implemented logic to determine locations for Wi-Fi access points based on the scan data, wherein the location information with potential error is excluded.