System and method for improving the quality of range measurement based upon historical data

• US 7,046,962 B1
• Filed: 07/18/2002
• Issued: 05/16/2006
• Est. Priority Date: 07/18/2002
• Status: Expired due to Term

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: MeshNetworks, Inc. (Motorola Solutions, Inc.)
• Inventors: Belcea, John M.
• Primary Examiner(s): To, Doris H.
• Assistant Examiner(s): DAO, MINH D
• Application Number:
  US10/197,573
• Time in Patent Office: 1,398 Days
• Field of Search: 455/67.11, 455/67.14, 455/67.16, 455/506, 455/515, 455/115.1, 455/115.3, 455/404.2, 455/421, 455/418
• US Class Current: 455/67.11
• CPC Class Codes: H04B 17/26 using historical data, averaging values or statistics

Abstract

A system and method for applying an algorithm to distance measurements between nodes in an ad-hoc communications network. The algorithm is located at an individual node of the ad-hoc network and processes collected data via a multi-path filter to ensure that range measurement data is correct, and if so, include such measurement data in a historical data matrix in which old measurement data is eliminated. During periods where received signals are unable to provide correct distance measurements due to reflections affecting the path between nodes or media absorption or radio energy, distance estimates may be obtained from this accurate historical data.

Claims

1. A method for controlling a node in a wireless ad-hoc communications network to provide distance measurement values between nodes of said network using historical data to achieve more accurate results, said method comprising:

controlling a first node to receive a plurality of signals from a second node of said network;

controlling said first node to calculate a distance between said first and second nodes based on said received signals, and to maintain a record of historical measurement data comprising past distance calculations by said first node which were accepted by a filter adapted to eliminate erroneous measurements, said filter having first and second stages; and

controlling said first node to provide at least one distance measurement value between said first and second nodes using at least one of said calculated distance and historical data; and

wherein said step of controlling said first node to provide at least one distance measurement value between said first and second nodes comprises controlling said first node to provide a distance measurement value based upon an approximation using a historical data matrix when said first node receives a number of direct signals from said second node wherein said number of direct signals is insufficient to allow an accurate distance measurement calculation between said first and second nodes using a Time Of Arrival measurement technique.

2. A method as claimed in claim 1, wherein:

said step of controlling said first node to receive said signals comprises controlling said first node to receive said signals via at least one of direct and reflected paths between said first and second nodes; and

said method further comprises controlling said first node to detect, differentiate and measure said signals.

3. A method as claimed in claim 1, wherein said step of controlling said first node to receive said signals comprises controlling said first node to receive said plurality of signals from said second node when said second node is in motion.

4. A method as claimed in claim 1, wherein said step of controlling said first node to calculate said distance comprises controlling said first node to calculate said distance between said first and second nodes based on said received signals using a Time Of Arrival measurement technique.

5. A method as claimed in claim 1, wherein said step of controlling said first node to maintain said record of historical measurement data comprises controlling said first stage of said filter to receive and compare each said calculated distance value with said historical data and in response to said comparison, accept or reject said calculated distance value.

6. A method as claimed in claim 5, wherein said step of controlling said first node to maintain said record of historical measurement data further comprises controlling said fir stage of said filter to reject a calculated distance value if said value is greater than a set limit.

7. A method as claimed in claim 5, wherein said step of controlling said first node to maintain said record of historical measurement data further comprises controlling said first stage of said filter to accept a calculated distance value if said value is less than or equal to a set limit.

8. A method as claimed in claim 1, wherein said step of controlling said first node to maintain said record of historical measurement data comprises controlling said second stage of said filter to receive each accepted value from said first stage of said filter and include each said accepted value in said historical data.

9. A method as claimed in claim 1, wherein said step of controlling said first node to maintain said record of historical measurement data comprises controlling said second stage of said filter to periodically review each value of said historical data and in response to said review, remove a value from said historical data if said value has become outdated.

10. A method as claimed in claim 1, wherein said step of controlling said first node to provide at least one distance measurement value between said first and second nodes comprises controlling said first node to provide a distance measurement value based upon signal Time Of Arrival analysis when said first node receives a number of direct signals from said second node wherein said number of direct signals is sufficient to allow an accurate distance measurement calculation between said first and second nodes using said Time Of Arrival measurement technique.

11. A method as claimed in claim 1, wherein said step of controlling said first node to provide at least one distance measurement value between said first and second nodes further comprises controlling said first node to provide a distance measurement value based upon an approximation using said historical data matrix and at least one of the following equations:

$\{\begin{array}{c}{a}_{1,1}<br><br>V+a_{1,2}<br><br>d_0=b_1\\ a_{2,1}<br><br>V+a_{2,2}<br><br>d_0=b_2\end{array}$

where a_1,1 represents a first value in said matrix, a_1,2 represents a second value within said matrix, a_2,1 represents a third value within said matrix, a_2,2 represents a fourth value within said matrix, b₁ represents a fifth value within said matrix and b₂ represents a sixth value within said matrix, and variables V and d₀ may be used to compute said approximate distance measurement value.

12. A method for controlling a node in a wireless ad-hoc communications network to provide distance measurement values between nodes of said network using historical data to achieve more accurate results, said method comprising:

controlling a fist node to receive a plurality of signals from a second node of said network;

controlling said first node to calculate a distance between said first and second nodes based on said received signals, and to maintain a record of historical measurement data comprising past distance calculations by said first node which were accepted by a filter adapted to eliminate erroneous measurements, said filter having first and second stages; and

controlling said first node to provide at least one distance measurement value between said first and second nodes using at least one of said calculated distance and historical data;

wherein said step of controlling said first node to maintain said record of historical measurement data comprises controlling said first node to create a historical data matrix comprising historical measurement data; and

said step of controlling said first node to maintain said record of historical measurement data comprises controlling said second stage of said filter to either include or remove a value in said historical data matrix using at least one of the following equations;

$a_{1,1}=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>t_i^2$ $a_{1,2}=a_{2,1}=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>t_i$ $a_{2,2}=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}$ $b_1=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>d_i<br><br>t_i$ $b_2=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>d_i$

where a_1,1 represents a first value in said matrix, a_1,2 represents a second value within said matrix, a_2,1 represents a third value within said matrix, a_2,2 represents a fourth value within said matrix, b₁ represents a fifth value within said matrix and b₂ represents a sixth value within said matrix, w represents a weight variable, and t represents a time at which a distance d exists between said first and second nodes.

13. A system adapted to provide distance measurement values between nodes of a wireless ad-hoc communications network using historical data to achieve more accurate results, said system comprising:

a controller adapted to control a first node to receive a plurality of signals from a second node of said network;

said controller further adapted to control said fire node to calculate a distance between said first and second nodes based on said received signals, and to maintain a record of historical measurement data comprising past distance calculations by said first node which were accepted by a filter adapted to eliminate erroneous measurements, said filter having first and second stages; and

said controller further adapted to control said first node to provide at least one distance measurement value between said first and second nodes using at least one of said calculated distance and historical data; and

wherein said controller is adapted to control said first node to provide a distance measurement value based upon an approximation using a historical data matrix when said first node receives a number of direct signals from said second node wherein said number of direct signals is insufficient to allow an accurate distance measurement calculation between said first and second nodes using a Time Of Arrival measurement technique.

14. A system as claimed in claim 13, wherein:

said controller is adapted to control said first node to receive said signals via at least one of direct and reflected paths between said first and second nodes; and

said first node is adapted to detect, differentiate and measure said signals.

15. A system as claimed in claim 13, wherein said controller is adapted to control said first node to receive said plurality of signals from said second node when said second node is in motion.

16. A system as claimed in claim 13, wherein said controller is adapted to control said first node to calculate said distance between said first and second nodes based on said received signals using a Time Of Arrival measurement technique.

17. A system as claimed in claim 13, wherein said controller is adapted to control said first stage of said filter to receive and compare each calculated distance value with said historical data and in response to said comparison, accept or reject each calculated distance value.

18. A system as claimed in claim 17, wherein said controller is further adapted to control said first stage of said filter to reject a calculated distance value if said value is greater than a set limit.

19. A system as claimed in claim 17, wherein said controller is further adapted to control said first stage of said filter to accept a calculated distance value if said value is less than or equal to a set limit.

20. A system as claimed in claim 13, wherein said controller is adapted to control said second stage of said filter to receive each accepted value from said first stage of said filter and include each said accepted value in said historical data.

21. A system as claimed in claim 13, wherein said controller is adapted to control said second stage of said filter to periodically review each value of said historical data and in response to said review, remove a value from said historical data if said value has become outdated.

22. A system as claimed in claim 13, wherein said controller is adapted to control said first node to provide a distance measurement value based upon signal Time Of Arrival analysis when said first node receives a number of directs from said second node wherein said number of direct signals is sufficient to allow an accurate distance measurement calculation between said first and second nodes using said Time Of Arrival measurement technique.

23. A system as claimed in claim 13, wherein said controller is adapted to control said first node to provide a distance measurement value based upon an approximation using said historical data matrix and at least one of the following equations:

$\{\begin{array}{c}{a}_{1,1}<br><br>V+a_{1,2}<br><br>d_0=b_1\\ a_{2,1}<br><br>V+a_{2,2}<br><br>d_0=b_2\end{array}$

where a_1,1 represents a first value in said matrix, a_1,2 represents a second value within said matrix, a_2,1 represents a third value within said matrix, a_2,2 represents a fourth value within said matrix, b₁ represents a fifth value within said matrix and b₂ represents a sixth value within said matrix, and variables V and d₀ may be used to compute said approximate distance measurement value.

24. A system adapted to provide distance measurement values between nodes of a wireless ad-hoc communications network using historical data to achieve more accurate results, said system comprising:

a controller adapted to control a first node to receive a plurality of signals from a second node of said network;

said controller further adapted to control said first node to calculate a distance between said first and second nodes based on said received signals, and to maintain a record of historical measurement data comprising least distance calculations by said first node which were accepted by a filter adapted to eliminate erroneous measurements, said filter having first and second stages; and

said controller further adapted to control said first node to provide at least one distance measurement value between said first and second nodes using at least one of said calculated distance and historical data;

wherein said controller is adapted to control said first node to create a historical data matrix comprising historical measurement data; and

said controller is adapted to control said second stage of said filter to either include or remove a value in said historical data matrix using at least one of the following equations;

$a_{1,1}=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>t_i^2$ $a_{1,2}=a_{2,1}=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>t_i$ $a_{2,2}=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}$ $b_1=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>d_i<br><br>t_i$ $b_2=\underset{i=1}{\overset{n}{\sum <br><br>}}<br><br><br><br>w^{n-i}<br><br>d_i$

where a_1,1 represents a first value in said matrix, a_1,2 represents a second value within said matrix, a_2,1 represents a third value within said matrix, a_2,2 represents a fourth value within said matrix, b₁ represents a fifth value within said matrix and b₂ represents a sixth value within said matrix, w represents a weight variable, and t represents a time at which a distance d exists between said first and second nodes.