TruePosition, ABI test network-based vs. handset-based 911 solutions

Fresh off the heels of the Federal Communications Commission taking steps to strengthen 911 location accuracy rules, network-based location solution company TruePosition Inc. published research that it says exposes the limitations of Assisted GPS for locating 911 calls.
The research, conducted with ABI Research, included making 3,500 911 calls in Frisco and Austin, Texas, using off-the-shelf cellphones. TruePosition uses Uplink Time Difference of Arrival, or (U-TDOA) for its network-based 911 solution, which is used by AT&T Mobility (T) and T-Mobile USA Inc. (DTEGY) Handset-based solutions use A-GPS technology and are used by Verizon Wireless (VZ) and Sprint Nextel Corp. (S)
“The testing data from Frisco and Austin shows that A-GPS did not perform well when the cell phone making the 911 call was indoors or when it was surrounded by tall buildings,” stated Dominique Bonte, Group Director of Telematics and Navigation for ABI Research. “In order for A-GPS to locate a phone, it requires that the cellphone have a clear line of sight with the GPS satellites. If that line of sight is blocked by steel and concrete of buildings, A-GPS technology will not locate the cellphone with sufficient accuracy or, most likely, will not be able to locate the phone at all.”
Nearly 70% of 911 calls are made from cellphones, the commission said. 911 calls made from landline networks are accurate 98% of the time, said FCC Chairman Julius Genachowski, but calls made from wireless networks are 50% less likely to be precise.
Testing was done at nine locations in Frisco and 10 in Austin in a variety of conditions, including indoors. Three different location technologies were used on three different air interfaces: U-TDOA on a GSM network, A-GPS with an Advanced Forward Link Trilateration (AFLT) fallback on a CDMA network, and A-GPS with a Round Trip Time (RTT) fallback on a UMTS network.