System and method for determining a position of a mobile unit
First Claim
1. A method of determining a position of a mobile unit in communication with a network that has at least three access points, the method comprising:
- obtaining and storing location co-ordinates of a plurality of reference points and access points of the network;
calculating and storing a physical distance between each one of the reference points and each one of the access points based on their stored co-ordinates in a database;
obtaining and storing access point received signal strength indicators received at each one of the reference points in the database, wherein each of the access point received signal strength indicators provides an indication of the signal strength of a signal sent from one of the access points;
determining coefficients of a polynomial function by curve fitting, wherein the coefficients are representative of a relationship between the stored access point received signal strength indicators and the stored physical distance between the reference points and each one of the access points and wherein the curve is representative of the propagation of the stored access points in an offline mode;
obtaining received signal strength indicators at the mobile unit from the access points;
calculating a physical distance between the mobile unit and each of the access points based on the received signal strength indicators obtained at the mobile unit and the coefficients for each of the access points; and
calculating a position of the mobile unit based on the calculated physical distances between the mobile unit and each of the access points;
wherein determining coefficients further comprises processing the database storing the received signal strength indicators of the access points and the physical distances between the reference points and the access points, and outputting the coefficients.
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Abstract
A system (1200) and a method (700, 800) are provided for determining the position of a mobile unit (MU) in communication with a network in an environment. A database (720) is provided with coefficients of a polynomial function representative of a relationship between received signal strength indicators (RSSIs) of network access points (APs) and physical distances (PDs) between reference points and each AP. RSSIs are obtained (725) at the MU from the APs and a physical distance is calculated (730) between the MU and each AP based on the RSSIs and the coefficients for each AP. The position of the MU is next calculated (735) based on the calculated PDs. When the environment comprises sub-regions with variable signal propagation characteristics, the method (800) determines coefficients for each sub-region and determines the sub-region in which the mobile unit is located with a fingerprint positioning method (802).
13 Citations
20 Claims
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1. A method of determining a position of a mobile unit in communication with a network that has at least three access points, the method comprising:
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obtaining and storing location co-ordinates of a plurality of reference points and access points of the network; calculating and storing a physical distance between each one of the reference points and each one of the access points based on their stored co-ordinates in a database; obtaining and storing access point received signal strength indicators received at each one of the reference points in the database, wherein each of the access point received signal strength indicators provides an indication of the signal strength of a signal sent from one of the access points; determining coefficients of a polynomial function by curve fitting, wherein the coefficients are representative of a relationship between the stored access point received signal strength indicators and the stored physical distance between the reference points and each one of the access points and wherein the curve is representative of the propagation of the stored access points in an offline mode; obtaining received signal strength indicators at the mobile unit from the access points; calculating a physical distance between the mobile unit and each of the access points based on the received signal strength indicators obtained at the mobile unit and the coefficients for each of the access points; and calculating a position of the mobile unit based on the calculated physical distances between the mobile unit and each of the access points; wherein determining coefficients further comprises processing the database storing the received signal strength indicators of the access points and the physical distances between the reference points and the access points, and outputting the coefficients. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for determining a position of a mobile unit in communication with a network, the system comprising:
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the mobile unit; at least three access points providing radio communication links for the network; a database; obtaining means adapted to obtain and store in the database location co-ordinates of a plurality of reference points and the access points of the network;
to obtain and store in the database access point received signal strength indicators received at each one of the reference points, wherein each of the access point received signal strength indicators provides an indication of the signal strength of a signal sent from one of the access points; and
to obtain received signal strength indicators at the mobile unit from the access points;determining means adapted to determine coefficients of a polynomial function in the database by curve fitting, wherein the coefficients are representative of a relationship between the stored access point received signal strength indicators and the stored physical distance between the reference points and each one of the access points and wherein the curve is representative of the propagation of the stored access points in an offline mode; calculating means adapted to calculate and store in the database a physical distance between each one of the reference points and each one of the access points based on their stored co-ordinates;
to calculate a physical distance between the mobile unit and each of the access points based on the received signal strength indicators obtained at the mobile unit and the coefficients for each of the access points; and
to calculate a position of the mobile unit based on the calculated physical distances between the mobile unit and each of the access points;wherein the determining means is further adapted to process the database storing the received signal strength indicators of the access points and the physical distances between the reference points and the access points, and to output the coefficients. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method of determining a position of a mobile unit in communication with a network that has at least three access points, the method comprising:
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obtaining and storing location co-ordinates of a plurality of reference points and access points of the network; calculating and storing a physical distance between each one of the reference points and each one of the access points based on their stored co-ordinates; obtaining and storing access point received signal strength indicators received at each one of the reference points, wherein each of the access point received signal strength indicators provides an indication of the signal strength of a signal sent from one of the access points; determining coefficients of a polynomial function representative of a relationship between the stored access point received signal strength indicators and the stored physical distance between the reference points and each one of the access points; obtaining received signal strength indicators at the mobile unit from the access points; calculating a physical distance between the mobile unit and each of the access points based on the received signal strength indicators obtained at the mobile unit and the coefficients for each of the access points; and calculating a position of the mobile unit based on the calculated physical distances between the mobile unit and each of the access points; wherein the network is in an environment comprising sub-regions, and the step of determining coefficients further comprises determining coefficients for each sub-region respectively. - View Dependent Claims (20)
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Specification