Method of determining the position of a mobile unit

• US 6,618,671 B2
• Filed: 09/20/2001
• Issued: 09/09/2003
• Est. Priority Date: 09/20/2000
• Status: Expired due to Term

• Current Assignee: Fox Digital, NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Marshall, Christopher B., Yule, Andrew T., Dooley, Saul R.
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US09/957,128
• Publication Number:
  US 20020049537A1
• Time in Patent Office: 719 Days
• Field of Search: 701/213, 701/214, 701/215, 701/216, 342/357, 342/357.03, 342/357.01, 342/357.02
• US Class Current: 701/213
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 19/51 Relative positioning
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0027 of actual mobile position, i.e. position determined on mobile
• CPC Class Codes: G01S 5/0063 of measured values, i.e. measurement on base station and position calculation on mobile

Abstract

A method of determining the position of a mobile unit (MS1) having a GPS receiver (24) is disclosed. The method comprising the steps of measuring mobile unit pseudoranges at the mobile unit (MS1) using the GPS receiver (24); providing reference pseudoranges corresponding to a reference location situated remote from the mobile unit (BS1); and determining the position of the mobile unit (MS1) relative to the reference location (BS1) as a function of both the reference pseudoranges and the mobile unit pseudoranges.

Claims

1. A method of determining the position of a mobile unit having a GPS receiver comprising the steps of:

measuring mobile unit pseudoranges at the mobile unit using the GPS receiver;

receiving GPS ephemeris data in the form of Keplerian parameters at a reference location located remote from the mobile unit;

calculating from the GPS ephemeris data satellite vector information in Cartesian form describing one of;

GPS satellite position information and GPS satellite movement information;

providing the GPS satellite vector information to the mobile unit; and

determining the position of the mobile unit as a function of the GPS satellite vector information and the mobile unit pseudoranges.

2. A method according to claim 1 wherein the satellite vector information comprises position vectors and velocity vectors describing the position and movement of said GPS satellites respectively.

3. A method according to claim 1 wherein the satellite vector information comprises acceleration vectors describing the movement of said GPS satellites.

4. A method according to claim 1 wherein the satellite vector information comprises fourth or higher order vectors describing the movement of said GPS satellites.

5. A method according to claim 1 wherein the GPS satellite position information is provided in the form of normalised direction vectors of the GPS satellites relative to the reference location.

6. A method according to claim 5 wherein the position of the mobile unit (X_m, Y_m, Z_m) relative to the reference location (X_ref, Y_ref, Z_ref) is determined using the following approximation:

$\left(\begin{array}{c}{X}_m-X_{\mathrm{ref}}\\ Y_m-Y_{\mathrm{ref}}\\ Z_m-Z_{\mathrm{ref}}\\ c_m-c_{\mathrm{ref}}\end{array}\right)\approx <br><br>H^{-1}<br><br>\left(\begin{array}{c}{\mathrm{PSR}}_{\mathrm{m1}}-{\mathrm{PSR}}_{\mathrm{ref1}}\\ {\mathrm{PSR}}_{\mathrm{m2}<br><br>\text{\hspace{1em}<br><br>}}-{\mathrm{PSR}}_{\mathrm{ref2}}\\ {\mathrm{PSR}}_{\mathrm{m3}}-{\mathrm{PSR}}_{\mathrm{ref3}}\\ {\mathrm{PSR}}_{\mathrm{m4}}-{\mathrm{PSR}}_{\mathrm{ref4}}\end{array}\right)$

where c_m and c_ref are the GPS clock errors at the mobile unit and the reference location respectively;

PSR_mn and PSR_refn are the mobile unit and reference pseudoranges respectively; and

wherein H<sup>−

1</sup> is the inverse of matrix H which includes normalised direction vectors of satellites relative to the reference location in the form;

$H=\left(\begin{array}{cccc}\frac{X_1-X_{\mathrm{ref}}}{R_{1-\mathrm{ref}}}& \frac{Y_1-Y_{\mathrm{ref}}}{R_{1-\mathrm{ref}}}& \frac{Z_1-Z_{\mathrm{ref}}}{R_{1-\mathrm{ref}}}& 1\\ \frac{X_2-X_{\mathrm{ref}}}{R_{2-\mathrm{ref}}}& \frac{Y_2-Y_{\mathrm{ref}}}{R_{2-\mathrm{ref}}}& \frac{Z_2-Z_{\mathrm{ref}}}{R_{2-\mathrm{ref}}}& 1\\ \frac{X_3-X_{\mathrm{ref}}}{R_{3-\mathrm{ref}}}& \frac{Y_3-Y_{\mathrm{ref}}}{R_{3-\mathrm{ref}}}& \frac{Z_3-Z_{\mathrm{ref}}}{R_{3-\mathrm{ref}}}& 1\\ \frac{X_4-X_{\mathrm{ref}}}{R_{4-\mathrm{ref}}}& \frac{Y_4-Y_{\mathrm{ref}}}{R_{4-\mathrm{ref}}}& \frac{Z_4-Z_{\mathrm{ref}}}{R_{4-\mathrm{ref}}}& 1\end{array}\right)$

where R_i-ref is the range between the i^th satellite and the reference location.

7. A method according to claim 1 wherein the GPS satellite position information is obtained from GPS satellite signals received by a GPS receiver located at the reference location.

8. A method according to claim 1 wherein the GPS satellite position information is provided using a GPS receiver located at the reference location.

9. A method according to claim 1 wherein the GPS satellite position information is provided by calculation based on the reference location and GPS satellite signal information obtained from GPS satellite signals received by a GPS receiver located remote from the reference location.

10. A method according to claim 1 wherein the GPS satellite vector information is provided by calculation based on the reference location and GPS satellite signal information obtained from a GPS receiver located remote from the reference location.

11. A method according to claim 1 wherein the mobile unit pseudoranges are transmitted from the mobile unit to a communications base station, and wherein the position of the mobile unit relative to the reference location is determined remote from the mobile unit.

12. A method according to claim 1 wherein the GPS satellite vector information is transmitted from a communications base station to the mobile unit, and wherein the position of the mobile unit relative to the reference location is determined at the mobile unit.

13. A method according to claim 12 further comprising the step of transmitting the position of the mobile unit relative to the reference location from the mobile unit to the communications base station.

14. A method according to claim 12 further comprising the step of transmitting the reference location from the communications base station to the mobile unit.

15. A method according to claim 14 further comprising the step of transmitting the absolute position of the mobile unit from the mobile unit to the communications base station.

16. A method according to claim 12 wherein the reference location geographically coincides with the location of the communications base station.

20. A method according to claim 12 wherein the reference location geographically coincides with the location of the communications base station.

22. A mobile unit comprising a GPS receiver and able to determine its position using a method according to claim 1.

17. A method of determining the position of a mobile unit having a GPS receiver comprising the steps of measuring pseudoranges at the mobile unit;

providing GPs satellite vector information to the mobile unit;

determining the position of the mobile unit relative to a nearby reference location using the pseudoranges and the GPS satellite vector information; and

determining the absolute position of the mobile unit from both the reference location and the relative location of the mobile unit to the reference location.

18. A method of determining the position of a mobile unit having a GPS receiver comprising the steps of measuring mobile unit pseudoranges at the mobile unit using the GPS receiver;

receiving GPS ephemeris data in the form of Keplerian parameters at a reference location located remote from the mobile unit;

calculating from the ephemeris data satellite vector information in Cartesian form describing either or both of the position or movement of GPS satellites;

providing the satellite vector information to the mobile unit; and

determining the position of the mobile unit as a function of the satellite vector information and the mobile unit pseudoranges.

19. A method according to claim 18 wherein the satellite vector information comprises position (x, y, z) and velocity ({dot over (x)}, {dot over (y)}, {dot over (z)}) vectors describing the position and movement of the GPS satellites respectively.

21. A method according to claim 18 wherein the satellite vector information comprises fourth or higher order vectors describing the movement of the GPS satellites.