Calibration of WLAN Access Points for Location Services

Wireless access points within a GPS-Unavailable environment can provide location services to user equipment devices within the environment provided that the access points are aware of their precise locations. In order to calibrate the locations of the wireless access points, a user equipment is moved to specific locations within the environment. At each of those locations, the user equipment transmits calibration signals that include the transmission location as well as a timestamp of the transmission time. Upon receipt by the access points, these signals are timestamped with a reception timestamp by a clock that is synchronized with the clock of the user equipment. After accumulating sufficient calibration information from a sufficient number of calibration locations, the access points can accurately determine their locations using trigonometric and other functions.