Wireless location using multiple location estimators

• US 6,249,252 B1
• Filed: 04/23/1999
• Issued: 06/19/2001
• Est. Priority Date: 09/09/1996
• Status: Expired due to Term

• Current Assignee: TracBeam LLC (Dennis J. Dupray)
• Original Assignee: TracBeam LLC (Dennis J. Dupray)
• Inventors: Dupray, Dennis J.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): PHAN, DAO LINDA
• Application Number:
  US09/299,115
• Time in Patent Office: 788 Days
• Field of Search: 342/450, 342/457, 342/357.01, 342/357.02, 455/456, 455/457, 701/213, 701/216
• US Class Current: 342/450
• CPC Class Codes: G01S 1/028 Simulation means, e.g. of beacon signals therefor for teaching or training purposes G09B9/00
• CPC Class Codes: G01S 2205/006 for emergency situations
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 2205/06 Emergency
• CPC Class Codes: G01S 5/0009 Transmission of position information to remote stations involving assistance data G01S5/0236
• CPC Class Codes: G01S 5/0018 Transmission from mobile station to base station
• CPC Class Codes: G01S 5/0054 of actual mobile position, i.e. position calculation on base station
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0244 Accuracy or reliability of position solution or of measurements contributing thereto
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 88/005 Data network PoA devices

Abstract

A location system is disclosed for commercial wireless telecommunication infrastructures. The system is an end-to-end solution having one or more location centers for outputting requested locations of commercially available handsets or mobile stations (MS) based on, e.g., CDMA, AMPS, NAMPS or TDMA communication standards, for processing both local MS location requests and more global MS location requests via, e.g., Internet communication between a distributed network of location centers. The system uses a plurality of MS locating technologies including those based on: (1) two-way TOA and TDOA; (2) pattern recognition; (3) distributed antenna provisioning; (5) GPS signals, (6) angle of arrival, (7) super resolution enhancements, and (8) supplemental information from various types of very low cost non-infrastructure base stations for communicating via a typical commercial wireless base station infrastructure or a public telephone switching network. Accordingly, the traditional MS location difficulties, such as multipath, poor location accuracy and poor coverage are alleviated via such technologies in combination with strategies for: (a) automatically adapting and calibrating system performance according to environmental and geographical changes; (b) automatically capturing location signal data for continual enhancement of a self-maintaining historical data base retaining predictive location signal data; (c) evaluating MS locations according to both heuristics and constraints related to, e.g., terrain, MS velocity and MS path extrapolation from tracking and (d) adjusting likely MS locations adaptively and statistically so that the system becomes progressively more comprehensive and accurate. Further, the system can be modularly configured for use in location signing environments ranging from urban, dense urban, suburban, rural, mountain to low traffic or isolated roadways. Accordingly, the system is useful for 911 emergency calls, tracking, routing, people and animal location including applications for confinement to and exclusion from certain areas.

Claims

1. A method for providing a location estimate of a wireless mobile station using measurements of wireless signals, comprising:

(a) first receiving, when available, a first collection of measurements of wireless signals transmitted between said mobile station and one or more satellites;

(b) second receiving a second collection of measurements of wireless signals transmitted between said mobile station and one or more terrestrial communication stations, at least when said first collection is not available, each said communication station including at least one of a receiver for receiving signals from, and a transmitter for transmitting signals to said mobile station;

(c) first determining a first location estimate of said mobile station using said first measurements according to an availability of said first collection;

(d) second determining a second location estimate of said mobile station using said second measurements according to an availability of said second collection, wherein said second location estimate is obtained from estimating a time of arrival (TOA) of a received signal relative to a time reference at each one of a plurality of wireless signal monitoring stations using an inverse transform whose resolution is greater than Rayleigh resolution;

(e) outputting a resulting location estimate obtained using at least one of said first and second location estimates.

2. A method as claimed in claim 1, wherein said steps of claim 1 are performed for a single emergency response request.

3. A method as claimed in claim 1, further including a step of outputting, to an emergency response center, said resulting location estimate of said mobile station in response to said emergency response request.

7. The method of claim 1, further including a step of monitoring a signal s(t) transmitted from the wireless mobile station at each one of a plurality of the communication stations, wherein said step of monitoring includes the steps following:

filtering, amplifying and demodulating the received signal s(t) thereby generating a filtered, amplified and demodulated signal r_i(t); and

estimating the TOA of the filtered, amplified and demodulated signal r_i(t) relative to a time reference.

4. A method for locating a mobile station using wireless signal measurements obtained from transmissions between said mobile station and a plurality of fixed location communication stations, wherein each of said communications stations includes one or more of a transmitter and a receiver for wirelessly communicating with said mobile station, comprising:

providing first and second mobile station location evaluators, wherein said location evaluators determine information related to one or more location estimates of said mobile station when said location estimators are supplied with data having values obtained from wireless signal measurements obtained via transmissions between said mobile station and the communication stations, wherein;

(A) said first location evaluator performs one or more of the following techniques (i), (ii) and (iii) when supplied with a corresponding instance of said data;

(i) a first technique for determining, for at least one of the communication stations, one of;

a distance, and a time difference of arrival between the mobile station and the communication station, wherein said first technique estimates a time of arrival (TOA) of a received signal relative to a time reference at each one of a plurality of wireless signal monitoring stations using an inverse transform whose resolution is greater than Rayleigh resolution;

(ii) a second technique for estimating a location of said mobile station, using values from a corresponding instance of said data obtained from signals received by the mobile station from one or more satellites;

(iii) a third technique for recognizing a pattern of characteristics of a corresponding instance of said data, wherein said pattern of characteristics is indicative of a plurality of wireless signal transmission paths between the mobile station and each of one or more of the communication stations; and

(B) for at least a particular one of said techniques performed by said first location estimator, said second location evaluator performs a different one of said techniques when supplied with a corresponding instance of said data for the different technique;

first generating, by said first location estimator, first location related information that is dependent upon an availability of a first corresponding instance of said data;

second generating, by said second location evaluator, second location related information that is dependent upon an availability of a second corresponding instance of said data;

determining a resulting location estimate of the mobile station dependent upon at least one of;

(a) a first value obtained from said first location related information, and (b) a second value obtained from said second location related information.

5. The method as claimed in claim 4, wherein one or more of said mobile station location evaluators generates a location estimate of said mobile station.

6. The method as claimed in claim 4, wherein said mobile station is co-located with a processor for activating at least one of said location estimators.

8. The method of claim 4, wherein one of said steps of first and second generating includes processing time difference of arrivals of said first technique for generating an estimate of the position of the mobile station by solving for one of (a) through (d) following:

(a) two coordinates using three of said communication stations using hyperbolic trilateration;

(b) three coordinates using four of said communication stations using hyperbolic trilateration;

(c) two coordinates using more than three of said communication stations using hyperbolic trilateration and one of parametric least squares, Kalman filtering or maximum likelihood; and

(d) three coordinates using more than four of said communication stations using hyperbolic trilateration and one of parametric least squares, Kalman filtering or maximum likelihood.