Hybrid satellite based positioning system

• US 20040189515A1
• Filed: 03/31/2003
• Published: 09/30/2004
• Est. Priority Date: 03/31/2003
• Status: Abandoned Application

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Vannucci, Giovanni
• Application Number:
  US10/403,715
• Publication Number:
  US 20040189515A1
• Time in Patent Office: Days
• US Class Current: 342/357.01
• CPC Class Codes: G01S 19/03 Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type

Abstract

A hybrid satellite positioning system determines the position of a mobile terminal. The system is hybrid in that it uses GPS satellites together with other satellites not meant for positioning to achieve a position fix. It is advantageous in urban areas, where it is difficult to see enough GPS satellites, but many direct broadcast (DBS) satellites signals are available. the DBS signals can be used in place of GPS signals to achieve a fix. The system includes a stationary server for time stamping an auxiliary radio signal received from an auxiliary radio source, such as DBS satellite, according to a GPS-derived time reference. A mobile terminal also receives the same auxiliary radio signal and time stamps it according to a mobile time reference. The mobile terminal is linked to the server through a wireless telecommunication link. Through the link, it obtains the time stamped auxiliary signal received by the server. The mobile terminal performs a correlation to determine a timing offset between the two versions of received auxiliary signal. Then, the position of the mobile terminal can be determined by combining that offset with observations of GPS signals.

Claims

1. A method for determining a position of a mobile terminal, comprising:

time stamping an auxiliary radio signal received from an auxiliary radio source in a stationary server according to a stationary time reference received in the stationary server from a satellite positioning system to generate a stationary time stamped signal representation;

time stamping the auxiliary radio signal received from the auxiliary radio source in a mobile terminal according to a mobile time reference received in the mobile terminal from the satellite positioning system to generate a mobile time stamped signal representation;

transmitting the stationary time stamped signal representation to the mobile terminal;

correlating the stationary time stamped signal representation with the mobile time stamped signal representation to generate a timing estimate; and

determining a position of the mobile terminal from the timing estimate and position data of the auxiliary radio source and the stationary server.

2. The method of claim 1 wherein the auxiliary radio source is a digital broadcasting satellite.

3. The method of claim 1 wherein the auxiliary source is a terrestrial broadcasting system.

4. The method of claim 1 wherein the auxiliary source is a wireless telephone system based on code division multiple access.

5. The method of claim 1 wherein the stationary server includes a reference auxiliary radio signal receiver, a reference satellite positioning system receiver and a digital link to a digital network, and the mobile terminal includes a mobile auxiliary radio signal receiver, a mobile satellite positioning system receiver and a wireless link to the digital network.

6. The method of claim 5 wherein the reference satellite positioning system receiver is equipped with a high-gain, directional antenna, and the mobile satellite positioning receiver is equipped with an omni-directional antenna.

7. The method of claim 1 wherein the stationary time stamped signal representation is transmitted to the mobile terminal via a wireless link.

8. The method of claim 1 wherein the stationary time stamped signal representation is transmitted to the mobile terminal via a wide area network.

9. The method of claim 1 further comprising:

quantizing the auxiliary radio signal; and

storing each sample as one bit in the time stamped signal representations.

10. The method of claim 1 further comprising:

transmitting periodically the stationary time stamped signal representation to a plurality of mobile terminals in broadcast mode.

11. The method of claim 1 further comprising:

transmitting the stationary time stamped signal representation to the mobile terminals in response to a request by the mobile terminal.

12. The method of claim 1 further comprising:

storing the stationary time stamped signal representation in a shared database accessible by the mobile terminal.

13. The method of claim 1 further comprising:

estimating a position of the mobile terminal; and

transmitting the estimated position of the mobile terminal to the stationary server.

14. The method of claim 1 further comprising:

correcting the timing estimate by calibration term.

15. The method of claim 1 further comprising:

periodically computing the calibration term in the mobile terminal from at least four timing signals in the mobile time reference.

16. The method of claim 14 further comprising:

periodically computing the calibration term in a plurality of calibration terminals; and

transmitting the calibration term to the mobile terminal.

17. A method for determining a position of a mobile terminal, comprising:

receiving an auxiliary radio signal from an auxiliary radio signal source in a stationary server;

receiving a stationary time reference received in the stationary server from a satellite positioning system;

time stamping the auxiliary radio signal according to the mobile time reference to generate a stationary time stamped signal representation;

receiving the auxiliary radio signal from the auxiliary radio signal source in a mobile terminal;

receiving a mobile time reference received in the mobile terminal from the satellite positioning system;

time stamping the auxiliary radio signal according to the mobile time reference to generate a mobile time stamped signal representation;

transmitting the stationary time stamped signal representation to the mobile terminal;

correlating the stationary time stamped signal representation with the mobile time stamped signal representation to generate a timing estimate; and

determining a position of the mobile terminal from the timing estimate and position data of the auxiliary radio source and the stationary server.

18. A system for determining a position of a mobile terminal, comprising:

a stationary server configured to time stamp an auxiliary radio signal received from an auxiliary radio source according to a stationary time reference received from a satellite positioning system to generate a stationary time stamped signal representation;

a mobile terminal configured to time stamping the auxiliary radio signal according to a mobile time reference to generate a mobile time stamped signal representation, the mobile terminal further comprising;

means for receiving the stationary time stamped signal representation;

means for correlating the stationary time stamped signal representation with the mobile time stamped signal representation to generate a timing estimate; and

means for determining a position of the mobile terminal from the timing estimate and position data of the auxiliary radio source and the stationary server.

19. A method for determining a position of a mobile terminal, comprising:

correlating a stationary time stamped signal representation of an auxiliary radio signal according to a stationary time reference at a fixed location with a mobile time stamped signal representation of the auxiliary radio signal according to a mobile time reference to generate a timing estimate; and

determining a position of the mobile terminal from the timing estimate and position data of the auxiliary radio source and the fixed location.