Subscription GPS information service system

• US 7,020,555 B1
• Filed: 12/23/2003
• Issued: 03/28/2006
• Est. Priority Date: 12/23/2003
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Janky, James M., Ciganer, Ann, Bird, David G.
• Primary Examiner(s): NGUYEN, TAN QUANG
• Application Number:
  US10/744,925
• Time in Patent Office: 826 Days
• Field of Search: 701/213, 701/214, 701/215, 342/358, 342/357.03, 342/357.12, 705/51, 713/153, 713/160, 713/161, 713/163, 455/12.1, 455/456.3, 340/539.13, 340/539.23
• US Class Current: 701/213
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/072 Ionosphere corrections
• CPC Class Codes: G01S 5/009 Transmission of differential positioning data to mobile

Abstract

A GPS information service system for providing supplemental GPS correction and signal acquisition information to subscribers. A GPS information server broadcasts GPS aiding information encrypted with subscription keys. A remote GPS subscription unit receives the key enablers for the subscription keys in service activation (SAM) messages for the services for which they have subscribed and then uses the subscription keys to decrypt the GPS aiding information. In order to prevent unauthorized access to the information, unsymmetrical signature generation and authentication algorithms are used for generating and authenticating signatures for the SAM messages.

Claims

1. A global positioning system (GPS) information server system, comprising:

at least one GPS correction reference station for generating GPS correction information for improving a GPS-based position estimate;

a GPS acquisition reference station for generating GPS acquisition information for reducing time for acquiring for GPS signal;

a transmitter station for broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal; and

a subscription encrypter for organizing said GPS correction and acquisition information into items and encrypting said items according to subscriptions, respectively, procured for remote subscription units, said GPS aiding signal received in said remote subscription units wherein only said remote subscription units having procured said subscriptions are enabled to decrypt said items.

2. The system of claim 1, wherein:

said GPS correction and acquisition information includes both carrier phase and pseudorange correction information in said single GPS aiding signal.

3. The system of claim 2, wherein:

said GPS correction and acquisition information further includes an accurate frequency, an accurate time, and GPS satellite orbital parameters said single GPS aiding signal.

4. A global positioning system (GPS) information server system, comprising:

at least one GPS correction reference station for generating GPS correction information for improving a GPS-based position estimate;

a GPS acquisition reference station for generating GPS acquisition information for reducing time for acquiring for GPS signal;

a transmitter station for broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal, wherein said GPS correction and acquisition information includes a sequence of expected GPS data bits for a certain future time; and

a remote GPS subscription unit for using said sequence for coherent integration of said GPS signal over a time period greater than a GPS data bit.

5. A global positioning system (GPS) information server system, comprising:

at least one GPS correction reference station for generating GPS correction information for improving a GPS-based position estimate;

a GPS acquisition reference station for generating GPS acquisition information for reducing time for acquiring for GPS signal;

a transmitter station for broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal, wherein said GPS correction and acquisition information includes a sequence of GPS data bits received at a certain past time and further comprising; and

a remote GPS subscription unit for storing a representation of said GPS signal and using said sequence for coherent integration of said GPS signal representation over a time period greater than a GPS data bit.

6. A global positioning system (GPS) information server system, comprising:

at least one GPS correction reference station for generating GPS correction information for improving a GPS-based position estimate;

a GPS acquisition reference station for generating GPS acquisition information for reducing time for acquiring for GPS signal;

a transmitter station for broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal;

a subscription encrypter for encrypting portions of said GPS correction and acquisition information with subscription keys, respectively; and

several remote subscription units for receiving said GPS aiding signal, each having a GPS information decrypter for decrypting said portions of said GPS correction and acquisition information in said remote subscription units having possession of said respective subscription keys.

7. The system of claim 6, wherein:

the subscription encrypter generates service activation (SAM) messages having key enablers and associated identifications, said key enablers corresponding to said subscription keys and said identifications corresponding to said remote subscription units;

the transmitter station broadcasts SAM signals having said SAM messages; and

the several remote subscription units receive said SAM signals, each having a SAM decrypter for determining said key enablers only in said remote subscription units having said associated identifications.

8. The system of claim 7, wherein:

the subscription encrypter includes an unsymmetrical signature generation algorithm for deriving signatures from said SAM messages, said signatures included in said SAM messages; and

the SAM decrypter includes an unsymmetrical signature authentication algorithm for authenticating said signatures and determining said key enablers, said unsymmetrical signature generation and authentication algorithms effectively preventing said signature authentication algorithm from being used to generate said signature generation algorithm.

9. The system of claim 7, wherein:

a one of said key enablers enables a one of said subscription keys to turn on a designated portion of said GPS correction and acquisition information until a designed date.

10. The system of claim 7, wherein:

a one of said key enablers enables a one of said subscription keys to turn on a designated portion of said GPS correction and acquisition information for a designated run time.

11. The system of claim 7, wherein:

a one of said key enablers enables a one of said subscription keys to turn off a designated portion of said GPS correction and acquisition information.

12. A method for aiding the global positioning system (GPS) system, comprising:

generating GPS correction information for correcting a GPS-based position estimate;

generating GPS acquisition information for increasing speed of acquisition of a GPS signal;

broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal;

organizing said GPS correction and acquisition information into items;

encrypting said items according to subscriptions, respectively, procured for remote subscription units; and

receiving said GPS aiding signal in said remote subscription units but only decrypting said items in said remote subscription units having said subscriptions.

13. The method of claim 12, wherein:

said GPS correction and acquisition information includes both carrier phase and pseudorange correction information in said single GPS aiding signal.

14. The method of claim 13, wherein:

said GPS correction and acquisition information further includes an accurate frequency, an accurate time, and GPS satellite orbital parameters in said single GPS aiding signal.

15. A method for aiding the global positioning system (GPS) system, comprising:

generating GPS correction information for correcting a GPS-based position estimate;

generating GPS acquisition information for increasing speed of acquisition of a GPS signal;

broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal, wherein said GPS correction and acquisition information includes a sequence of expected GPS data bits for a certain future time;

using said sequence in a remote GPS receiver for coherent integration of said GPS signal over a time period greater than a GPS data bit.

16. A method for aiding the global positioning system (GPS) system, comprising:

generating GPS correction information for correcting a GPS-based position estimate;

generating GPS acquisition information for increasing speed of acquisition of a GPS signal;

broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal, wherein said GPS correction and acquisition information includes a sequence of GPS data bits received at a certain past time; and

storing a representation of said GPS signal in a remote GPS subscription unit; and

using said sequence in said remote GPS subscription unit for coherent integration of said GPS signal representation over a time period greater than a GPS data bit.

17. A method for aiding the global positioning system (GPS) system, comprising:

generating GPS correction information for correcting a GPS-based position estimate;

generating GPS acquisition information for increasing speed of acquisition of a GPS signal;

broadcasting said GPS correction information and said GPS acquisition information in a single GPS aiding signal;

encrypting portions of said GPS correction and acquisition information with subscription keys, respectively;

receiving said GPS aiding signal in several remote subscription units; and

decrypting said portions of said GPS correction and acquisition information in said remote subscription units having possession of said respective subscription keys.

18. The method of claim 17, further comprising:

generating service activation (SAM) messages having key enablers and associated identifications, said key enablers corresponding to said subscription keys and said identifications corresponding to said remote subscription units;

broadcasting SAM signals having said SAM messages;

receiving said SAM signals in said several remote subscription units; and

determining said key enablers only in said remote subscription units having said associated identifications.

19. The method of claim 17, wherein:

generating said SAM messages includes using an unsymmetrical signature generation algorithm for deriving signatures from said SAM messages and including said signatures in said SAM messages; and

determining said key enablers includes authenticating said signatures using an unsymmetrical signature authentication algorithm, said unsymmetrical signature generation and authentication algorithms effectively preventing said signature authentication algorithm from being used to generate said signature generation algorithm.

20. The method of claim 17, wherein:

a one of said key enablers enables a one of said subscription keys to turn on a designated portion of said GPS correction and acquisition information until a designed date.

21. The method of claim 17, wherein:

a one of said key enablers enables a one of said subscription keys to turn on a designated portion of said GPS correction and acquisition information for a designated run time.

22. The method of claim 17, wherein:

a one of said key enablers enables a one of said subscription keys to turn off a designated portion of said GPS correction and acquisition information.