Communications: directive radio wave systems and devices (e.g. – Directive – Position indicating
Reexamination Certificate
2007-06-26
2007-06-26
Tarcza, Thomas H. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Directive
Position indicating
C342S174000, C342S463000
Reexamination Certificate
active
10976509
ABSTRACT:
Techniques for reducing the complexity and improving the accuracy of receive signal strength based location systems. The system comprises a plurality of radio sensor devices placed at known positions within a space in which devices are to be located. According to one technique, the path loss is measured between all combinations of pairs of radio sensor devices based on a test signal transmitted by each radio sensor device. A path loss model is evaluated to compute modeled path loss data between all combinations of pairs of radio sensor devices. For each measured path loss, a path loss error relative to each radio sensor device is computed by taking the difference between the measured path loss and the modeled path loss. The path loss error relative to each radio sensor device at any candidate position is interpolated from the computed path loss errors. A path loss estimate between a candidate position and each radio sensor device is computed by adding the interpolated path loss error relative to that radio sensor device at the candidate position and path loss data obtained by evaluating the path loss model based on the distance between at each candidate position and the corresponding radio sensor device. When determining the position of a device emitting radio signals (called a target device), the improved path loss estimate is used. According to another technique, for each radio sensor device, parameters are derived for a path loss model function from the measured path loss between that radio sensor device and each of the other radio sensor devices using a minimization computation. Then, a path loss estimate between a position and each radio sensor device is computed by evaluating the path loss model function using the parameters derived for each radio sensor device.
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Sugar Gary L.
Tesfai Yohannes
Cognio, Inc.
Edell Shapiro & Finnan LLC
Mull Fred H.
Tarcza Thomas H.
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