Multiple pass location processor

• US 20050206566A1
• Filed: 05/05/2005
• Published: 09/22/2005
• Est. Priority Date: 01/08/1999
• Status: Active Grant

• Current Assignee: Skyhook Holding, Inc. (Liberty Broadband Corp.)
• Original Assignee: TruePosition Incorporated
• Inventors: Anderson, Robert J., Ward, Matthew L., Stilp, Louis A.
• Granted Patent: US 7,271,765 B2
• Time in Patent Office: Days
• US Class Current: 342/455
• CPC Class Codes: G01S 1/026 of associated receivers
• 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 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0215 Interference
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/02216 Timing or synchronisation of the receivers
• CPC Class Codes: G01S 5/0244 Accuracy or reliability of position solution or of measurements contributing thereto
• CPC Class Codes: G01S 5/0246 involving frequency difference of arrival or Doppler measurements G01S5/02685 takes precedence
• CPC Class Codes: G01S 5/02521 using a radio-map
• 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: G01S 5/0284 Relative positioning
• 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 4/90 Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
• 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 76/50 for emergency connections
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A multiple pass location processing method, for use in a wireless location system (WLS), comprises identifying a received transmission as requiring multiple pass location processing whereby the WLS produces a first, lower quality location estimate and then subsequently produces a second, higher quality location estimate. The WLS then produces the first location estimate and provides it to a first location application, and then produces the second location estimate. The second location estimate may be a more accurate estimate than the first location estimate and/or of a higher confidence than the first location estimate. This method is suitable, but not limited, for use in connection with locating a wireless transmitter involved in an emergency services call and routing the call to a call center.

Claims

1. A wireless location system comprising:

a network connection which is capable of receiving, from a plurality of signal collection systems, data indicative of a signal from a transmitter received at the signal collection systems;

a location processor in communication with said network connection comprising a processor for processing at least a subset of said data indicative of signals from a transmitter to determine a location of said transmitter; and

a database in communication with said location processor and storing a location record indicative of said location of said transmitter, said database storing information for use in indicating to a location processor a particular subset of said signal collection systems to begin collecting data indicative of the signals from the transmitter, said information comprising the identity of the wireless transmitter.

2. The system as recited in claim 1 wherein said database is a relational database.

3. The system as recited in claim 1 wherein said database comprises a routing table having information indicative of the identity of a network element that should receive the location of the transmitter.

4. The system as recited in claim 3 wherein the network element is a PSAP.

5. The system as recited in claim 3 wherein the routing table comprises information based on the location of the transmitter.

6. The system as recited in claim 1 wherein the transmitter comprises a cellular telephone.

7. The system as recited in claim 1 wherein the signal collection systems are co-located proximate a wireless carrier cell site.

8. The system as recited in claim 1 wherein the location processor is capable of locating a cellular telephone using at least one time difference of arrival calculation.

9. The system as recited in claim 6 wherein the cellular telephone transmits a signal according to an air interface protocol selected from one of TDMA, CDMA, GSM, TACS, ESMR, AMPS and N-AMPS.

10. A wireless location system comprising:

means for receiving, from a plurality of signal collection systems, data indicative of signals from a transmitter received at the signal collection systems;

means for communicating with said network connection for processing at least a subset of said data indicative of signals from a transmitter to determine a location of said transmitter as a function of a time difference of signal arrival; and

database means in communication with said location processor for storing a location record indicative of said location of said transmitter;

said database means storing information for use in indicating, to a location processor a particular subset of said signal collection systems, to begin collecting data indicative of the signals from the transmitter;

said information comprising the identity of the wireless transmitter.

11. The system as recited in claim 10 wherein said database means comprises a routing table having information indicative of the identity of a network element that should receive the location of the transmitter.

12. The system as recited in claim 11 wherein the routing table comprises information based on the location of the transmitter.

13. The system as recited in claim 10 wherein the transmitter comprises a cellular telephone.

14. The system as recited in claim 10 wherein the signal collection systems are co-located proximate a wireless carrier cell site.

15. A wireless location process comprising:

receiving, from a plurality of signal collection systems, data derived from signals from a transmitter received at the signal collection systems;

processing at least a subset of said data derived from signals from a transmitter to determine a location of said transmitter as a function of a time difference of signal arrival; and

storing a location record indicative of said location of said transmitter in a database;

said database storing information for use in indicating, to a location processor a particular subset of said signal collection systems, to begin deriving data from representations of the signals from the transmitter;

said information comprising the identity of the wireless transmitter.

16. The process as recited in claim 15 wherein said database comprises a routing table having information indicative of the identity of a network element that should receive the location of the transmitter.

17. The process as recited in claim 16 wherein the routing table comprises information based on the location of the transmitter.

18. The process as recited in claim 15 wherein the transmitter comprises a cellular telephone.

19. The process as recited in claim 15 wherein the signal collection systems are co-located proximate a wireless carrier cell site.

20. The process as recited in claim 15 wherein the function of a time difference of signal arrival uses a Kalman filter.