System and method of estimating the position of a mobile terminal in a radio telecommunications network
First Claim
1. A method of estimating a position of a mobile terminal operating in a coverage area of a radio telecommunications network having a plurality of base station transceivers and a plurality of service area sectors, said method comprising the steps of:
- determining, for a plurality of positions throughout the coverage area of the network, expected Received Signal Strength (RSS) values of a signal transmitted by the base station transceivers and received by a typical mobile terminal;
storing the expected RSS values at a plurality of locations in a database;
obtaining, by the mobile terminal for which the position is to be estimated, RSS measurements of signals transmitted by the base station transceivers;
comparing the RSS measurements obtained from the mobile terminal with the expected RSS values stored in the database; and
estimating the position of the mobile terminal based on differences between the RSS measurements and the expected RSS values.
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Accused Products
Abstract
A system and method of estimating the position of a mobile terminal (MT) operating in a radio telecommunications network. Expected Received Signal Strength (RSS) values are predicted by a computer-aided prediction tool, and/or are measured by a test MT from base station transceivers. The predicted and measured RSS values are then tagged to indicate whether each value was predicted or measured. The RSS values are then stored at a plurality of locations in a database. When RSS measurements are received from the MT being located, a covariance matrix is used to compute metrics for the locations in the database. If more than a threshold percentage of the locations were populated with measured values, a Maximum-Likelihood (ML) estimator is used to estimate the position of the MT. If fewer than the threshold percentage of locations were populated with measured values, a Minimum-Mean-Square-Error (MMSE) estimator is used to estimate the position.
67 Citations
27 Claims
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1. A method of estimating a position of a mobile terminal operating in a coverage area of a radio telecommunications network having a plurality of base station transceivers and a plurality of service area sectors, said method comprising the steps of:
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determining, for a plurality of positions throughout the coverage area of the network, expected Received Signal Strength (RSS) values of a signal transmitted by the base station transceivers and received by a typical mobile terminal;
storing the expected RSS values at a plurality of locations in a database;
obtaining, by the mobile terminal for which the position is to be estimated, RSS measurements of signals transmitted by the base station transceivers;
comparing the RSS measurements obtained from the mobile terminal with the expected RSS values stored in the database; and
estimating the position of the mobile terminal based on differences between the RSS measurements and the expected RSS values. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of estimating a position of a mobile terminal operating in a coverage area of a radio telecommunications network having a plurality of base station transceivers and a plurality of service sectors, said method comprising the steps of:
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determining, for a plurality of positions throughout the coverage area of the network, expected Received Signal Strength (RSS) values of a signal transmitted by the base station transceivers and received by a typical mobile terminal, said determining step comprising;
predicting the expected RSS values for a first portion of the positions with a computer-aided prediction tool; and
taking actual measurements of the RSS of signals transmitted by the base station transceivers and received by a test mobile terminal for a second portion of the positions;
storing the expected RSS values at a plurality of locations in a database with an indicator for each location indicating whether each stored value is a predicted value or a measured value, said storing step including;
storing in the database, for each service sector, a first expected measurement variance for all locations in the database that are populated with measured values; and
storing in the database, for each service sector, a second expected measurement variance for all locations in the database that are populated with predicted values;
obtaining, by the mobile terminal for which the position is to be estimated, RSS measurements of signals transmitted by the base station transceivers;
weighting the RSS measurements obtained by the mobile terminal with the first expected measurement variance for locations in the database that are populated with measured values;
weighting the RSS measurements obtained by the mobile terminal with the second expected measurement variance for locations in the database that are populated with predicted values; and
comparing the weighted RSS measurements with the expected RSS values stored in the database;
estimating the position of the mobile terminal based on differences between the weighted RSS measurements and the expected RSS values, said estimating step comprising;
determining whether the percentage of locations being considered in the database that are populated with measured values exceeds a predefined threshold;
utilizing an estimator based on a maximum-likelihood criterion to estimate the position, upon determining that the percentage of locations being considered in the database that are populated with measured values exceeds the predefined threshold; and
utilizing an estimator based on a minimum-mean-square-error criterion to estimate the position, upon determining that the percentage of locations being considered in the database that are populated with measured values does not exceed the predefined threshold.
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21. A system for estimating a position of a mobile terminal operating in a coverage area of a radio telecommunications network having a plurality of base station transceivers and a plurality of service sectors, said system comprising:
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means for determining expected Received Signal Strength (RSS) values of signals transmitted by the base station transceivers and received by a typical mobile terminal for a plurality of positions throughout the coverage area of the network;
means for storing the expected RSS values at a plurality of locations in a database;
means for measuring by the mobile terminal for which the position is to be estimated, the RSS of signals transmitted by the base station transceivers; and
means for comparing the RSS measurements obtained by the mobile terminal with expected RSS values, and estimating the position of the mobile terminal based on differences between the RSS measurements and the expected RSS values. - View Dependent Claims (22, 23, 24, 25)
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26. A method of populating a database with expected Received Signal Strength (RSS) values for a typical mobile terminal operating in a coverage area of a radio telecommunications network having a plurality of base station transceivers that transmit radio signals received by the mobile terminal, said method comprising the steps of:
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determining, for a plurality of positions throughout the coverage area of the network, expected RSS values of a signal transmitted by the base station transceivers and received by the typical mobile terminal, said determining step comprising the steps of;
predicting the expected RSS values for a first portion of the positions with a computer-aided prediction tool; and
taking actual measurements of the RSS of signals transmitted by the base station transceivers and received by a test mobile terminal for a second portion of the positions; and
storing the predicted and measured expected RSS values at a plurality of locations in the database. - View Dependent Claims (27)
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Specification