US Patent 7499711 Transmitter location for ultra-wideband, transmitted-reference CDMA communication system

A system and method involve determining the location of objects within an area of interest using wireless signals. The system includes at least three base stations communicating with a central processor and a plurality of mobile devices. Further, at least one fixed beacon transmitter of known location may be provided. The mobile devices transmit a wireless signal to the base stations, which then determine a location of the mobile devices based on time difference of arrival information between the mobile devices measured at all the base stations.