Patent ID: 8315648

Claim:
A method for determining an approximate range from a location measurement unit (“LMU”) to a mobile device, comprising: (a) receiving at said LMU an uplink signal from said mobile device; (b) determining an uplink frame marker from said uplink signal; (c) receiving at said LMU a downlink signal from a base station serving said mobile device; (d) determining a downlink slot marker from said downlink signal; (e) determining a round trip propagation delay based on said uplink frame marker and said downlink slot marker; and (f) determining an approximate range from said LMU to said mobile device as a function of said round trip propagation delay, wherein the step of determining the downlink slot marker includes: (i) receiving downlink signals from neighboring base stations, (ii) correlating all received downlink signals for a predetermined chip delay, and (ii) non-coherently adding all correlated signals.