System and method for enhancing the accuracy of a location estimate

• US 7,911,384 B2
• Filed: 05/19/2008
• Issued: 03/22/2011
• Est. Priority Date: 10/16/2002
• Status: Expired due to Fees

• Current Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Alles, Martin, Gravely, Thomas B., Carlson, John P., Kennedy, Jr., Joseph P.
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US12/122,942
• Publication Number:
  US 20080238777A1
• Time in Patent Office: 1,037 Days
• Field of Search: 342/451, 342/457, 342/463, 342/465, 455/456.1, 455/456.6
• US Class Current: 342/451
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: H04B 1/1081 Reduction of multipath noise by equalising H04B7/005
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 7/0848 Joint weighting
• CPC Class Codes: H04B 7/0854 using error minimizing algorithms, e.g. minimum mean squared error [MMSE], "cross-correlation" or matrix inversion
• CPC Class Codes: H04B 7/086 using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
• CPC Class Codes: H04B 7/0891 Space-time diversity rake receivers H04B1/7115; space-time decoding H04L1/0631
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for enabling a system to enhance the accuracy of a location estimate modifies weights in a weight matrix associated with receiver station measurements in parallel with successive refinements of the location estimate. In a typical location estimation scenario, several receiving stations simultaneously derive measurements of a signal from the emitter. Any one of these measurements is in general some function of the emitter location and the receiving station location. The aggregate of these measurements is often in excess of the minimum number of measurements required to provide an estimate of the emitter location. Where such an excess exists, the method proceeds by modifying the weights associated with the measurements in parallel with successive refinements of the location estimate. The method can be implemented over various cellular protocols with a consistent and significant enhancement in the accuracy of location estimates.

Claims

1. A method for geo-locating a wireless transmitter emitting a signal comprising;

receiving the signal at a predetermined number of sensors, said predetermined number of sensors being greater than the minimum number of sensors required to obtain the geo-location estimate, and signals from the sensors containing information used to estimate the location contain a bias error;

determining a geo-location estimate of the wireless transmitter based on information from the predetermined number of sensors; and

updating the geo-location estimate by recursive analysis of the bias error to thereby refine the geo-location estimate.

2. The method of claim 1 wherein the predetermined number of sensors is four.

3. The method of claim 1 wherein the received signals from the sensors are provided at a location estimation device.

4. The method of claim 3 wherein the location estimation device determines the geo-location of the wireless transmitter by a method selected from the group consisting of time of arrival, time difference of arrival, frequency difference of arrival, and angle of arrival.

5. The method of claim 3 wherein the location estimation device determines the geo-location of the wireless transmitter by a plurality of methods selected from the group consisting of time of arrival, time difference of arrival, frequency of arrival, and angle of arrival.

6. The method of claim 1, further comprising determining which one of the sensors has the highest contribution to the bias error and updating the geo-location estimate without information from the one sensor.

7. The method of claim 3, wherein the location estimation device is remote from the wireless transmitter.