Location Pattern Matching Location Determination

The Location Pattern Matching (LMP) 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, Angle of Arrival 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 equipped with special gear.
• The receivers send the caller's voice call to the mobile switch, where sophisticated equipment analyzes the acoustic radio signal, and then compares it to a database of standard signal characteristics. These characteristics include signal reflections (multipath), echoes and other signal "anomalies." According to U.S. Wireless, the only supplier of gear for this technique, when a computerized match is made, the location of the caller can be determined within the FCC's requirements. The technique is effective in urban environments that include tall buildings and other obstructions, where other techniques might not succeed.
• The caller's voice call and the latitude and longitude are then sent to the PSAP for use by the dispatcher.

Wireless 911 page