Radio-frequency pattern matching (RFPM) is the engine that enables the use of mobile-phone signals to locate wireless devices in any environment, including dense downtown areas and indoors. This exciting technology leverages the power of the database to improve location accuracy to within 50 meters in even the toughest signal environments. Significant advances in RFPM technology have been made over the last 10 years. The system described here is deployed in more than 24 wireless networks to provide the location of E-911 callers and help save lives. For simplicity, we focus on the RFPM using signal strengths even though the technology also works with arrival times, signal-to-noise ratios, differential signal strengths and any signal parameter that varies in a predictable fashion over the coverage area.
展开▼
