Method and system for timebase synchronization

• US 20020167934A1
• Filed: 03/08/2002
• Published: 11/14/2002
• Est. Priority Date: 03/09/2001
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Johnson, Paul K., Carter, Stephen S.
• Granted Patent: US 7,373,175 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging

Abstract

A server-assisted approach for synchronizing timebases (120 and 140) in a client-server system utilizes global positioning system (GPS) receivers (136 and 110) at both the client and server. In a typical implementation, the GPS receiver (136) associated with the client system receives fragmentary or incomplete data from satellites that are part of the GPS. Thus, the client GPS receiver (136) is capable of receiving only fragmentary information and cannot derive accurate time signals therefrom. The server system (102) is associated with a GPS receiver (110) capable of generating accurate time and position data based on signals from GPS satellites (114). The fragmentary information from the client GPS receiver (136) is transmitted to the server (126) along with time information indicating the time at which the client captured the fragmentary GPS data. The server (126) analyzes the fragmentary GPS data with respect to the complete GPS data available from the GPS receiver (110) associated with the server. The server (126) accurately determines the actual time at which the fragmentary GPS data was captured and transmits timing signals to the client (146). The timing signals are used to correct the client timebase (140) thus synchronizing the client and server timebases (140 and 120).

Claims

1. A system for time-base synchronization, comprising:

a first base station transceiver system (BTS) having a transmitter and receiver;

a timing circuit associated with the first BTS to maintain time;

a global positioning system (GPS) receiver associated with the first BTS to receive at least partial location data, the first BTS providing the partial location data and a capture time at which the partial location data was received;

a second BTS communicating with the first BTS to receive the partial location data and the capture time from the first BTS;

a processor communicatively coupled to the second BTS and receiving the partial location data and time therefrom; and

a GPS receiver associated with the processor to provide complete location data to the processor, the processor processing the complete location data and partial location data to determine therefrom an accurate time at which the partial location data was received, the second BTS providing to the first BTS time data related to the accurate time at which the partial location data was received.

2. The system of claim 1 wherein the time data transmitted to the first BTS is the accurate time at which the partial location data was received.

3. The system of claim 1 wherein the time data transmitted to the first BTS is a time error indicating a difference between the capture time and the accurate time at which the partial location data was received.

4. The system of claim 1, further comprising a computer network coupling the first and second BTS wherein communication of the partial location data and the capture time from the first BTS to the second BTS and the time data related the accurate time at which the partial location data was received from the second BTS to the first BTS uses the computer network.

5. The system of claim 1 wherein communication of the partial location data and the capture time from the first BTS to the second BTS and the time data related the accurate time at which the partial location data was received from the second BTS to the first BTS uses a wireless connection between the first and second BTS.

6. The system of claim 1 wherein the processor is a portion of the second BTS.

7. A system for server-assisted time-base synchronization, comprising:

a first timing circuit to maintain time;

a first global positioning system (GPS) receiver to capture at least partial location data;

a client processor to provide the partial location data and a capture time at which the partial location data was captured;

a server processor communicatively coupled to the client processor and receiving the partial location data and capture time therefrom; and

a second GPS receiver associated with the server processor to provide complete location data to the server processor, the server processor processing the complete location data and partial location data to determine therefrom an accurate time at which the partial location data was captured, the server processor providing to the client processor time data related to the accurate time at which the partial location data was captured.

8. The system of claim 7 wherein the time data transmitted from the server processor to the client processor is the accurate time at which the partial location data was captured.

9. The system of claim 7 wherein the time data transmitted from the server processor to the client processor is a time error indicating a difference between the capture time and the accurate time at which the partial location data was captured.

10. The system of claim 7, further comprising a computer network coupling the client processor and the server processor wherein communication between the client processor and the server processor uses the computer network.

11. The system of claim 10 wherein the computer network is the Internet.

12. The system of claim 7, further comprising first and second transceivers associated with the client and server processors, respectively, wherein communication between the client processor and the server processor uses a wireless communication link between the first and second transceivers.

13. The system of claim 7 wherein the second GPS receiver is co-located with the server processor.

15. The method of claim 14 wherein the time data provided to the timing circuit is the accurate time at which the partial location data was captured.

16. The method of claim 14 wherein the time data provided to the timing circuit is a time error indicating a difference between the capture time and the accurate time at which the partial location data was captured.

17. The method of claim 14 wherein providing the providing time data comprises transmitting the time data via a computer network.

18. The method of claim 17 wherein the computer network is the Internet.

19. The method of claim 14 wherein providing the partial location data and a capture time comprises transmitting the partial location data and a capture time via a computer network.

20. The method of claim 19 wherein the computer network is the Internet.

21. The method of claim 14 for use with first and second transceivers associated with the timing circuit and server, respectively, wherein communication between the timing circuit and the server uses a wireless communication link between the first and second transceivers.

22. The method of claim 14 wherein the second GPS receiver is co-located with the server.

24. The method of claim 23 wherein analyzing the partial location data is performed with respect to complete location data provided by a second GPS receiver associated with the server.

14. A method for server-assisted time-base synchronization, comprising:

maintaining time with a timing circuit;

capturing at least partial location data using a first global positioning system (GPS) receiver;

providing the partial location data and a capture time at which the partial location data was captured to a server;

capturing complete location data using a second global positioning system (GPS) receiver associated with the server;

processing the complete location data and partial location data to determine therefrom an accurate time at which the partial location data was captured; and

providing time data related the accurate time at which the partial location data was captured to the timing circuit.

23. A method for server-assisted time-base synchronization, comprising:

maintaining time with a timing circuit;

capturing at least partial location data using a first global positioning system (GPS) receiver;

providing the partial location data and a capture time at which the partial location data was captured to a server;

analyzing the partial location data to determine therefrom an accurate time at which the partial location data was captured; and

providing time data related the accurate time at which the partial location data was captured to the timing circuit.