Patent ID: 6677895
Filing Date: 2004-01-13
Classification: G01S,H04W

Abstract:
A system for determining the location of a transmitting mobile unit comprising:a mobile unit having a Global Positioning System (GPS) unit and transmitter for transmitting an RF signal comprising an identification of the mobile unit and GPS location coordinates or other data obtained from the GPS unit, if available; a plurality of base stations forming a cellular telephone network; at least one location determination receiver contained within an area of the cellular telephone network having good GPS reception for receiving a transmitted signal from the mobile unit when in the area relating to the identification of the mobile unit and the GPS location coordinates or other data obtained from the GPS unit; a processor operatively connected to the at least one location determination receiver for determining the location of the mobile station based only on the transmitted signal from the mobile unit having GPS location coordinates or other data obtained from the GPS unit; and in an area of the cellular telephone network having poor GPS reception, a plurality of location determination receivers different from the location determination receivers contained within the area having good GPS reception and associated with the base stations of the cellular telephone network in the area having poor GPS reception and forming an overlay network to the cellular telephone network for receiving transmitted signals from the mobile unit when in the area having poor GPS reception relating to an identification of the mobile unit and for measuring the angle of arrival and/or the time of arrival, or multipath profile of transmitted signals from the mobile unit for use in determining the location of the mobile unit based only on the angle of arrival and/or the time of arrival or multipath profile.