Wireless positioning approach using time delay estimates of multipath components

• US 20050281363A1
• Filed: 06/08/2005
• Published: 12/22/2005
• Est. Priority Date: 06/09/2004
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Qi, Yihong, Asai, Takahiro, Suda, Hirohito
• Granted Patent: US 7,519,136 B2
• Time in Patent Office: Days
• US Class Current: 375/349
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A wireless positioning apparatus (10, 30, 50) includes a multipath delay estimator (11) configured to estimate multipath delay components from one or more received signals; a selector (13, 53) configured to select appropriate delay estimates from the estimated multipath delay components according to a predetermined criterion; a storage (15, 55) configured to store an NLOS delay function defining prior (statistics of) information about non-line-of-sight delays; and a position estimator (17, 57) configured to estimate a position of a mobile station based on the selected delay estimates and the NLOS delay function read out from the storage.

Claims

1. A wireless positioning apparatus comprising:

a multipath delay estimator configured to estimate multipath delay components from one or more received signals;

a selector configured to select appropriate delay estimates from the estimated multipath delay components according to a predetermined criterion;

a storage configured to store a non-line-of-sight (NLOS) delay function defining prior information about NLOS delays; and

a position estimator configured to estimate a position of a mobile station based on the selected delay estimates and the NLOS delay function read out from the storage.

2. A wireless positioning apparatus of claim 1, further comprising:

a time-difference-of-arrival (TDOA) data generator configured to create TDOA data from the selected delay estimates;

wherein the position estimator estimates the position of the mobile station based on the TDOA data, in place of the selected delay estimates, as well as on the NLOS delay function read out from the storage.

3. The wireless positioning apparatus of according to claim 1, wherein the selector selects a line-of-sight (LOS) delay estimate of LOS propagation if there is one in the multipath delay components, and further selects NLOS delay estimates that satisfy a predetermined condition among NLOS delay estimates of NLOS propagation.

4. The wireless positioning apparatus of claim 3, wherein the selector selects those NLOS delay estimates such that variances of those NLOS delay estimates are smaller that a first threshold and that the signal strength corresponding to those NLOS delay estimates is greater than a second threshold.

5. The wireless positioning apparatus of claim 3, wherein the selector has an NLOS determination unit that determines whether the multipath delay components are estimated from a received NLOS signal.

6. The wireless positioning apparatus of claim 1, further comprising:

a second position estimator configured to estimate the position of the mobile station in a reduced dimension space if the mobile station and involved base station(s) are in a particular geometry.

7. The wireless positioning apparatus of claim 6, wherein the second position estimator includes:

a BS-MS configuration detector configured to determine whether the mobile station and the base station are in the particular geometry; and

a dimension-reduced position estimator configured to produce a positioning parameter in the reduced dimension space if it is determined that the mobile station and the base station are in the particular geometry.

8. A wireless positioning method comprising steps of:

estimating multipath delay components from each of a plurality of received signals;

selecting appropriate delay estimates from the multipath delay components so as to conform to a predetermined criterion; and

estimating a location of a mobile station based on the selected delay estimates and a non-line-of-sight (NLOS) delay function defining prior information of NLOS delays.

9. The method of claim 8, further comprising the steps of:

generating time-difference-of-arrival (TDOA) data based on the selected delay estimates;

wherein the location of the mobile station is estimated based on the TDOA data, in place of the selected delay estimated, as well as on the NLOS delay function.

10. The method of claim 8, wherein the selecting step includes selecting a line-of-sight (LOS) delay estimate of LOS propagation if there is one in the multipath delay components, and further selecting NLOS delay estimates that satisfy a predetermined condition among delay estimates of NLOS propagation.

11. The method of claim 10, wherein the NLOS delay estimate is selected such that variances of the NLOS delay estimates are smaller than a first threshold and that the signal strength corresponding to the NLOS delay estimates is greater than a second threshold.

12. The method of claim 10, further comprising the step of determining whether the multipath delay components are estimated from a received NLOS signal.

13. The method of claim 8, further comprising the steps of:

determining whether the mobile station and one or more involved base stations are in a particular geometry that can be reduced in a lower dimension space; and

estimating the position of the mobile station in the reduced dimension space if the mobile station and the involved base station(s) are in the particular geometry.

14. The method of claim 13, wherein the determination step further includes the steps of:

determining whether there are enough base stations for current estimation; and

estimating an optimum parameter for the reduced dimension space if there are not enough base stations, while leaving the parameter in the rest of the dimensions to be randomly selected in a feasible region.