There are many methods for positioning, but they do not all make sense for telephony. Therefore, many of the methods possible are not employed for positioning cellular mobile devices. We provide a brief introduction to each of those methods here.
This method is based on mounting sensors on and/or within a moving platform. This method provides self-contained determination of motion by measuring changes in various parameters such as force angular velocity, and time.
Otherwise known as deduced reckoning, this method involves deducing position by extrapolating from a known prior position modified by a known velocity and direction.
This method has an accuracy of about one to five degrees and is very sensitive to tilt errors – if tilted 10-15 degrees, this method will induce directional errors.
This method requires at transmitter and receiver. This method is subject to errors from magnetic field fluctuations, which can be caused by the proximity of conducting objects and/or magnetic fields.
This method requires line-of-sight, a target, and a sensor. This method can be very accurate when a known point is used in conjunction with a highly precise medium such as a laser.
This method uses high frequency sound waves and can employ various alternative techniques including triangulation, time of flight, and phase differences. Acoustical methods are thus the most like many telephony methods whereas the latter uses an electromagnetic signal rather than sound waves for positioning.
There are many methods for determining position, and some work much better than others commercially with some more suited to mobile devices including U-TDOA, A-GPS, and others (RFID, WiFi, etc.)
For more information, see: