Development of Optimization
Techniques for
Enhanced 911 (E911) Wireless Location, 16-9175
Principal Investigators
Richard L. Johnson
Brent W. Fessler
Inclusive Dates: 01/01/00 - 01/01/01
Background - On June 12, 1996, the U.S. Federal Communications Commission adopted the E911 First Report and Order that required providers of wireless telephone services to locate mobile 9-1-1 callers and to furnish the fix information to the appropriate public service answering point (PSAP). After several revisions, the current location accuracy standard was given in the E911 Third Report and Order that stated:
"For network-based solutions: no more than 100 meters error for 67 percent of calls, and 300 meters for 95 percent of calls;
For handset-based solutions: no more than 50 meters for 67 percent of calls, and 150 meters for 95 percent of calls."
Approach - This research effort was to develop computer models to predict location performance for network-based and handset-based wireless telephone location systems.
The research team extended SwRI's modeling capability to include: 1) a realistic deployment of base stations, 2) tri-sector antenna arrays at each base station, 3) urban multipath and propagation effects, and 4) wideband and narrowband propagation models.
Accomplishments - The modeling and analysis capabilities developed during this work are being promoted with the wireless carriers to assist in the selection of appropriate location technologies for a variety of coverage areas. SwRI's engineering services include trade-off analyses between angle-of-arrival/time-difference-of-arrival/time-of-arrival network-based location systems. An additional ongoing promotional effort is to offer engineering services to PSAPs and wireless carriers to verify location performance after the systems have been deployed.
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A plot of 67-percent circular error probabilities gives the radius of a circle that has a 67-percent probability of containing the caller. |
