Angle of Arrival Location Determination

The Angle of Arrival (AOA) method of locating a wireless caller is just one of several that may be selected by wireless carriers to meet Phase II requirements by October, 2001. The Time Difference of Arrival, location pattern matching and GPS methods are additional methods being considered. There are also hybrid location methods that use both TDOA and AOA technology. The TDOA, AOA and location pattern matching methods are network based, while the GPS method is handset based.

Using this technique:

• A wireless subscriber can use any handset (digital, analog, TDMA, CDMA, no special add-ons) to make a 911 call.
• The wireless phone's signal is received at various antenna sites. Each antenna site is equipped with additional gear to detect the compass direction from which the caller's signal is arriving. Generally, at least three sites must receive the handset signal to provide an accurate location.
• The receivers send the caller's voice call and compass data to the mobile switch, where the angles are compared and computed to generate a latitude and longitude for the caller.
• The caller's voice call and the latitude and longitude are then sent to the PSAP for use by the dispatcher.

Also see the Nexus Telocations Web site for information about AOA.

Wireless 911 page