Mobile Geolocation Techniques For Location-Aware Emergency Response Services

The Wireless Emergency Alerts (WEA) system uses cellular broadcasts to send emergency messages to cell phones in the area affected by an emergency (target area or TA). The granularity of cell broadcast areas limits geotargeting accuracy and results in False Positives (cell phones outside the TA getting the emergency message) and/or False Negatives (cell phones in the TA not getting the message). We have proposed a scheme where the mobile device uses its knowledge of its own geolocation to filter received emergency messages and alerts the user only if the mobile is inside the TA. This scheme can leverage the geolocation capabilities available in cellular systems for navigation and E911 applications. In this paper, we evaluate and compare many geolocation techniques in terms of their effectiveness for WEA filtering application. Based on the comparisons, we recommend a specific set of techniques working together as the best solution. We also identify changes required, if any, in the basic schemes to make them more effective for our filtering application. Finally, we discuss general considerations in a broader set of applications that use the geolocation capabilities of mobile devices.