Method, and associated apparatus, for determining geographic positioning of a wireless communication station operable in a non-ideal propagation environment

• US 6,282,426 B1
• Filed: 06/08/1999
• Issued: 08/28/2001
• Est. Priority Date: 06/08/1999
• Status: Expired due to Fees

• Current Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Original Assignee: Nokia Mobile Phones UK Limited (Nokia Corporation)
• Inventors: Wang, Shu-Shaw
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/327,848
• Time in Patent Office: 812 Days
• Field of Search: 455/456, 455/457, 342/357.06, 342/450, 342/452, 342/453, 342/451, 342/464
• US Class Current: 455/456.3
• CPC Class Codes: G01S 19/428 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/02528 Simulating radio frequency fingerprints
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

Apparatus, and an associated method, for determining the geographical positioning of a wireless communication station when the wireless communication station is operated in a non-ideal propagation environment. Errors introduced by NLOS conditions in a determination of a position of the wireless communication station calculated by way of a trilateration technique are corrected. If too few signals are received at the wireless communication station to permit a determination of its position using a ray tracing pattern recognition technique, an estimate of the position of the wireless communication station is also determinable. When implemented in a cellular communication system, accurate position determinations are made even when the mobile station is operated in a non-ideal propagation environment, such as an urban area.

Claims

1. Apparatus for determining geographic positioning of a mobile station operable in a radio communication system installed to encompass a geographical area and in which the mobile station receives at least a first TOA (time-of-arrival) signal generated by a first TOA-signal-source, said apparatus comprising:

a zonal portion determiner coupled to receive indications of at least information related to the first TOA-signal received at the mobile station, said zonal portion determiner for determining a zonal portion of the geographical area encompassed by the radio communication system in which the mobile station is positioned;

a ray tracer operable responsive to determinations made by said zonal portion determiner of the zonal portion in which the mobile station is positioned, said ray tracer for simulating ray paths from each of the at least first TOA-signal source; and

a mobile station position determiner coupled to receive values representative of simulated ray paths generated by said ray tracer, said mobile station position determiner for determining an actual position of the mobile station responsive to the values representative of the simulated ray paths.

2. The apparatus of claim 1 further comprising a database storage element, said database storage element coupled to receive values representative of simulated ray paths generated by said ray tracer, the values stored at storage locations of said database storage element forming a database of values, and wherein said mobile station position determiner is coupled to receive the values stored at said database storage element.

3. The apparatus of claim 2 wherein the mobile station receives the first TOA-signal, wherein the indications to which said zonal position determiner is coupled to receive, comprise indications of a coverage area of the first TOA-signal source, respectively.

4. The apparatus of claim 3 wherein the zonal portion of the geographical area in which the mobile station is determined by said zonal portion determiner to be positioned comprises the coverage area of the first TOA-signal source.

5. The apparatus of claim 4 wherein said zonal portion determiner further defines grid points at selected positions within the coverage area.

6. The apparatus of claim 5 wherein the ray paths simulated by said ray tracer simulate paths of rays extending between each of the at least first TOA-signal source and each grid point defined by said zonal portion determiner.

7. The apparatus of claim 6 wherein the paths of rays simulated by said ray tracer are represented by values, the values forming a location database, and the values used to define predicted locations of the mobile station.

8. The apparatus of claim 7 wherein said mobile station position determiner is coupled to receive the values stored at the location database, and wherein the actual position of the mobile station is determined responsive to comparisons between selected values stored at the location database and corresponding values derived from the at least the first TOA-signal.

9. The apparatus of claim 1 wherein the at least first TOA-signal comprises the first TOA-signal, a second TOA-signal, and at least a third TOA-signal, wherein the mobile station further includes a location fix positioner operable responsive to the first, second, and third TOA-signals, respectively, to generate a location fix indicative of a location-fix-positioner determined location of the mobile station and wherein the indications, to which said zonal portion determiner is coupled to receive, comprise indications of the location fix.

10. The apparatus of claim 9 wherein the zonal portion of the geographical area in which the mobile station is determined by said zonal portion determiner to be positioned comprises a location zone centered at the location fix.

11. The apparatus of claim 10 wherein said zonal portion determiner further defines grid points at selected positions within the location zone.

12. The apparatus of claim 11 wherein the geographical area further comprises topographical features having height-wise dimensions and wherein said zonal portion determiner further associates the height-wise dimensions of the topographical features with the location zone.

13. The apparatus of claim 12 wherein, when a selected position at which said zonal portion determiner defines grid points corresponds with a topographical feature having a height-wise dimension, said zonal portion determiner defines the grid point thereat to include at least one height-wise dimension.

14. The apparatus of claim 13 wherein the topographical feature having the height-wise dimension comprises a multi-level construction and wherein the at least one height-wise dimension of the grid point comprises a height-wise dimension associated with each level of the multi-level construction.

15. The apparatus of claim 11 wherein the ray paths simulated by said ray tracer simulate paths of rays extending between each TOA-signal source and each grid point defined by said zonal portion determiner.

16. The apparatus of claim 15 wherein the paths of rays simulated by said ray tracer are represented by values, the values forming a correction table, and the values used to define predicted locations of the location fix.

17. The apparatus of claim 16 wherein said mobile station position determiner determines the actual position of the mobile station by matching the location fixed with values taken from the correction table associated with a predicted location of the predicted locations positioned most closely to the location fix.

18. A method for determining geographic positioning of a mobile station operable in a radio communication system installed to encompass a geographic area in which the mobile station receives at least a first TOA(time-of-arrival) signal generated by a first TOA-signal source, said method comprising:

selecting a zonal portion of the geographical area encompassed by the radio communication system in which the mobile station is positioned representative to the indications of at least information related to the at least the first TOA-signal;

simulating ray paths from each of the at least the first TOA-signal source, responsive to determinations made during said operation of selecting; and

determining an actual position of the mobile station responsive to values representative of the simulated ray paths.

19. The method of claim 18 comprising an initial operation of detecting how many of the at least the first TOA-signal are received at the mobile station;

and, if at least three TOA-signals are received at the mobile station further performing the operation of calculating a location fix at the mobile station, the location fix forming the indications responsive to which the zonal portion is selected during said operation of selecting.

20. The method of claim 19, if fewer than three TOA-signals are received at the mobile station, further comprising performing the operation of determining a coverage area of the first TOA-signal source, the coverage area forming the indications responsive to which the zonal portion is selected during said operation of selecting.