Abstract: Ground-based pseudolites support accurate determination of mobile receiver locations by broadcasting CDMA signals interleaved by a TDMA system. Pseudolites synchronize signal transmissions with an accurate timing reference, such as can be derived from GPS satellites. Adjacent pseudolites broadcast CDMA signals at different times, eliminating near-far signal interference between pseudolites. A mobile receiver, typically a cellular telephone, receives and enables determination of times of arrival (TOA) of the pseudolite signals. A location processor associated with the mobile receiver may access an internal database of pseudolite locations, or pseudolite location information may be encoded in pseudolite transmissions. The location processor uses pseudolite location information and TOA to determine mobile receiver location. The TDMA pseudolite-based system may augment the GPS to provide more accurate location information than is available from the GPS alone.

Abstract: The present invention combines the measured characteristics of a radio signal in a communications environment with collateral information to produce an accurate and economical way to locate a mobile transmitter station, such as a mobile telephone, in a cellular telephone network.

Abstract: An apparatus and method for combining the measured characteristics of a radio signal in a communications environment with collateral information to produce an accurate and economical way to locate a mobile transmitter station, such as a mobile telephone, in a cellular telephone network.

Abstract: A system and method for locating a mobile transceiver relative to plural fixed sensor stations. The system includes plural sensor stations that receive a signal transmitted by the mobile transceiver. A probable position of the mobile transceiver is determined based on a time of arrival of the signal and an angle of arrival of the signal received at the plural sensor stations.

Abstract: A method and apparatus for locating a mobile radio communications transceiver in a cellular-telephone or cellular-like communications system use a simplified system for passive monitoring of the signals emitted by the transceiver. Two receiving base stations can determine the timing of signal arrivals from the remote transceiver. This timing information is then combined with collateral, position-sensitive information to determine the likely location of the transceiver. The present invention has particular applicability to roadway transportation in that it facilitates enhanced emergency services and roadside assistance in response to calls for assistance, and it permits the passive monitoring of traffic flow.