Wireless position measurement terminal and wireless position measurement system

• US 20010051527A1
• Filed: 02/26/2001
• Published: 12/13/2001
• Est. Priority Date: 06/13/2000
• Status: Abandoned Application

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kuwahara, Mikio, Doi, Nobukazu, Yano, Takashi, Ishifuji, Tomoaki
• Application Number:
  US09/791,862
• Publication Number:
  US 20010051527A1
• Time in Patent Office: Days
• US Class Current: 455/456.6
• CPC Class Codes: G01S 2205/008 using a mobile telephone network
• CPC Class Codes: G01S 5/0045 Transmission from base station to mobile station G01S5/009 takes precedence
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: H04B 1/70754 Setting of search window, i.e. range of code offsets to be searched H04B1/70758 takes precedence

Abstract

A wireless position measurement terminal, a wireless position measurement system, and a method for performing delay profile calculation window sizing in a wireless position measurement system, are disclosed. The terminal includes a delay profile calculating circuit, and a window setter connected to the delay profile calculating circuit that varies a range for a delay profile calculating window according to at least one information item within a remote received signal. The terminal may additionally include a memory circuit that stores positional information, wherein the window setter changes the range according to a correlation of the positional information and the information item. The system includes the terminal, and at least three base stations, wherein at least one of the base stations provides the remote received signal to the terminal. The method includes the steps of receiving the remote signal, including the information item, sizing of a delay profile calculation window according to the information item, estimating of propagation distances between the terminal and each base station by a calculating of a delay profile of each base station, and triangulating of the then-present location of the terminal based on propagation distances.

Claims

1. A wireless position measurement terminal for calculating a location, comprising:

a delay profile calculating circuit that calculates delay profiles for at least one remote received signal; and

a window setter communicatively connected to said delay profile calculating circuit, wherein said window setter varies a range for a delay profile calculating window for said delay profile calculating circuit according to at least one information item, wherein the at least one information item is within at least one of the at least one remote received signals.

2. The wireless position measurement terminal of

claim 1

, further comprising:

a memory circuit that stores positional information for a first plurality of base stations, wherein at least one base station of said first plurality of base stations sends the information item to the terminal in one of the at least one remote received signals, and wherein said window setter changes the range according to a correlation of the positional information and the information item.

3. The wireless position measurement terminal of

claim 2

, wherein the at least one information item comprises the base station having maximum power received at the terminal, and wherein said window setter varies the range according to the positional information of the base station having maximum power received.

4. The wireless position measurement terminal of

claim 2

, wherein the range is varied by selecting three base stations, including the base station having maximum power received, and selecting by said window setter of a range equivalent to an average distance of the positional information between the three selected base stations added to a predetermined margin.

5. The wireless position measurement terminal of

claim 3

, wherein the positional information includes one range for each of a rural, an urban and a highly congested area, and wherein the information item comprises in which of the rural, the urban, or the congested areas the terminal is.

6. The wireless-position measurement terminal of

claim 1

, wherein the at least one information item is received from one base station, and wherein the at least one information item comprises the range necessary for calculation of the delay profiles of at least two base stations other than the one base station.

7. The wireless position measurement terminal of

claim 6

, wherein the one base station comprises the base station having maximum received power at the terminal.

8. The wireless position measurement terminal of

claim 1

, wherein a reference time for the calculation of the delay profiles is determined from the information item, and wherein the range comprises at least one forward portion and at least one backward portion from the reference time of a base station sending the information item, and wherein the forward portion and backward portion are sufficiently forward and backward from the reference time to allow a calculation of at least two delay profiles of at least two other base stations not sending the information item.

9. The wireless position measurement terminal of

claim 1

, further comprising a position calculator wherein, upon completion of the calculation of the delay profiles of at least three base stations by said delay profile calculating circuit from at least three remote received signals, the terminal calculates propagation times between the terminal and the at least three base stations based on the at least three delay profiles, wherein said position calculator calculates an actual position of the terminal based on the at least three propagation times and the information item.

10. The wireless position measurement terminal of

claim 1

, wherein the range in a first area wherein base stations are densely populated is smaller than the range in a second area wherein base stations are less densely populated than in the first area.

11. A wireless position measurement system that performs delay profile calculation window sizing for a terminal, wherein the window sizing is correspondent to a population density of base stations in a then-present location of the terminal, comprising:

the terminal;

at least three base stations, wherein at least one of said at least three base stations provides at least one signal to the terminal, wherein at least one of the at least one signals includes at least one information item;

wherein the terminal receives the at least one signal transmitted from at least one of said at least three base stations, and wherein the terminal estimates propagation distances between the terminal and each of said at least three base stations by calculating a delay profile of each base station, and wherein the delay profiles of all of said at least three base stations are calculated in a window sized by the terminal according to the at least one information item; and

wherein the terminal triangulates the then-present location of the terminal based on the at least three propagation distances.

12. The wireless position measurement system of

claim 11

, further comprising a center, wherein the at least one information item is stored in said center, and wherein the terminal receives the at least one information item over a wireless connection with said center via at least one of the at least one signals.

13. The wireless position measurement system of

claim 11

, wherein the terminal comprises:

a memory circuit that stores positional information of a first plurality of base stations, wherein the first plurality of base stations includes at least one of said at least three base stations;

wherein at least one of the at least one of said at least three base stations in the first plurality of base stations sends the information item to the terminal in one of the at least one signals, and the terminal changes the window size according to a correlation of the positional information and the information item.

14. The wireless position measurement system of

claim 13

, wherein the at least one information item comprises the base station having maximum power received at the terminal, wherein the terminal changes the window size according to the positional information of the base station having maximum power received.

15. The wireless position measurement system of

claim 11

, wherein the at least one information item is received from one primary base station of said at least three base stations, and wherein the at least one information item comprises the window size needed for calculation of the delay profiles of said at least two base stations other than the one primary base station.

16. The wireless position measurement system of

claim 11

, wherein a reference time for the calculation of the delay profiles is determined from the information item, and wherein the window size comprises at least one forward portion and at least one backward portion from the reference time of the one of said at least three base station that is sending the information item, and wherein the forward portion and backward portion are sufficiently forward and backward from the reference time to allow a calculation of at least two delay profiles of said at least two base stations not sending the information item.

17. A method for performing delay profile calculation window sizing for a terminal in a wireless position measurement system, wherein the window sizing is correspondent to a population density of base stations in a then-present location of the terminal, comprising:

receiving at least one signal at the terminal from at least one of at least three base stations, wherein at least one of the at least one signals includes at least one information item;

sizing of a delay profile calculation window according to the at least one information item;

estimating of propagation distances between the terminal and each of the at least three base stations by a calculating of a delay profile of each base station, wherein the delay profiles of all of the at least three base stations are calculated in the window sized by the terminal according to the at least one information item; and

triangulating of the then-present location of the terminal based on the at least three propagation distances.

18. The method of

claim 17

, further comprising:

storing the at least one information item in a center; and

receiving the at least one information item over a wireless connection with the center via at least one of the at least one signals.

19. The method of

claim 17

, further comprising:

storing positional information of a first plurality of base stations, wherein the first plurality of base stations includes at least one of the at least three base stations;

sending by at least one of the at least one of said at least three base stations in the first plurality of base stations of the information item to the terminal in one of the at least one signals;

correlating the positional information and the information item; and

changing the window size according to said correlating of the positional information and the information item.

20. The method of

claim 17

, further comprising receiving the at least one information item from one primary base station of the at least three base stations, wherein the at least one information item comprises the window size needed for said calculating of the delay profiles of the at least two base stations other than the one primary base station.

21. The method of

claim 17

, further comprising:

determining a reference time for the calculation of the delay profiles from the information item;

determining a window size comprising at least one forward portion and at least one backward portion from the reference time of the one of the at least three base station that is sending the information item, wherein the forward portion and the backward portion are determined sufficiently forward and backward from the reference time to allow a calculation of at least two delay profiles of the at least two base stations not sending the information item.