The State of Cellular Probes

Cellular probe technology is one of several potentially promising technologies for obtaining accurate travel time information. In 1996, the Federal Communications Commission (FCC) mandated E911 requirements that cellular location be provided when 911 emergency calls come in to emergency management authorities. The E911 requirements allow 50 -300 meters from the emergency call location, depending on the type of cellular phone technology used and whether handset-based or network-based solutions are deployed. This paper investigates the current state of cellular probe technologies. Recent studies and field tests are reviewed and summarized. As of March 2003, at least four location technologies have been partially or fully deployed. Although these solutions have the accuracy to provide acceptable travel time information, E911 technologies were developed for a different purpose. The use of the E911 infrastructure for probe activities introduces additional concerns such as privacy issues, the need to provide multiple locations on individual phones, and the effects on the carrier networks occasioned by the need to determine large numbers of locations. Further research is recommended in several areas. These include the improvement of cellular geolocation technologies for cellular probes, the establishment of a publicprivate partnership between transportation agencies and cellular carriers to support probe activities, and the investigation of institutional issues and challenges ahead in order to more effectively deploy cellular probe technologies.