Locating and tracking a user in a wireless network through environmentally profiled data
First Claim
1. A method for determining a location of a mobile unit, comprising:
- measuring a wireless signal strength;
comparing the measured wireless signal strength to an environmentally profiled table of wireless signal strengths and known locations of the mobile unit, wherein the environmentally profiled table is selected based on the selected table having a closest determined location of a base station from among a plurality of tables of wireless signal strengths and the known locations of the mobile unit, which tables reflect the influence of environmental factors;
finding a table entry whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength; and
, determining the location of the mobile unit with reference to the found table entry.
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Accused Products
Abstract
A method for locating a user in a wireless network is disclosed. A mobile computer which seeks to determine its location within a building detects the signal strength of one or more wireless base stations placed at known locations throughout the building. An environmentally profiled table of known locations within the building and the base station signal strength at those locations is searched to find the stored signal strength most similar to the signal strength detected. The location corresponding to the most similar stored signal strength is determined to be the current location of the mobile computer. The table can be derived empirically, by placing a mobile computer at the known locations and measuring the signal strength of the wireless base stations at those locations, or it can be derived mathematically by taking into account a reference signal strength, the distance between the reference point and the known location, and the number of intervening walls between the reference point and the known location. As an alternative, the base stations can measure the signal strength of the mobile computer. In such a case, the table would relate a known position of the mobile computer to the signal strength of the mobile computer as measured by the one or more base stations. Environmental profiling is achieved by comparing several different tables, corresponding to several different environments, and using the table that minimizes the error. Environmental profiling can be applied to tables determined empirically or mathematically.
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Citations
46 Claims
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1. A method for determining a location of a mobile unit, comprising:
- measuring a wireless signal strength;
comparing the measured wireless signal strength to an environmentally profiled table of wireless signal strengths and known locations of the mobile unit, wherein the environmentally profiled table is selected based on the selected table having a closest determined location of a base station from among a plurality of tables of wireless signal strengths and the known locations of the mobile unit, which tables reflect the influence of environmental factors;
finding a table entry whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength; and
, determining the location of the mobile unit with reference to the found table entry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
- measuring a wireless signal strength;
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17. A computer-readable medium having computer-executable instructions for performing steps, comprising:
- measuring a wireless signal strength;
comparing the measured wireless signal strength to an environmentally profiled table of wireless signal strengths and known locations of the mobile unit, wherein the environmentally profiled table is selected based on the selected table having a closest determined location of a base station from among a plurality of tables of wireless signal strengths and the known locations of the mobile unit, which tables reflect the influence of environmental factors;
finding a table entry whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength; and
, determining the location of the mobile unit with reference to the found table entry. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
- measuring a wireless signal strength;
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33. A method for creating an environmentally profiled table of wireless signal strengths and known locations using at least two base stations, a first base station at a known first base station location and a second base station, the method comprising:
- (a) generating a plurality of tables of wireless signal strengths and the known locations;
(b) measuring, at the first base station, a wireless signal strength of the second base station;
(c) comparing the measured wireless signal strength of the second base station to one of the plurality of tables of wireless signal strengths and the known locations;
(d) finding an entry in the one of the plurality of tables of wireless signal strengths and the known locations whose wireless signal strength is closest by distance in signal space, to the measured signal strength of the second base station;
(e) determining a location of the first base station with reference to the found table entry;
(f) computing a deviation by comparing the determined location of the first base station to the known first base station location;
repeating steps (a) through (f) for each of the plurality of tables of wireless signal strengths and the known locations; and
, selecting, as the environmentally profiled table, a table of the plurality of tables which minimized the deviation. - View Dependent Claims (34, 35)
- (a) generating a plurality of tables of wireless signal strengths and the known locations;
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36. A method for creating an environmentally profiled table of wireless signal strengths and known locations using at least two base stations, a first base station at a known first base station location and a second base station, the method comprising:
- (a) generating the plurality of tables of wireless signal strengths and the known locations;
(b) measuring, at the second base station, a wireless signal strength of the first base station;
(c) comparing the measured wireless signal strength of the first base station to one of the plurality of tables of wireless signal strengths and the known locations;
(d) finding an entry in the one of the plurality of tables of wireless signal strengths and the known locations whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength of the first base station;
(e) determining a location of the first base station with reference to the found table entry;
(f) computing a deviation by comparing the determined location of the first base station to the known first base station location;
repeating steps (a) through (f) for each of the plurality of tables of wireless signal strengths and the known locations; and
, selecting, as the environmentally profiled table, a table of the plurality of tables which minimized the deviation. - View Dependent Claims (37, 38)
- (a) generating the plurality of tables of wireless signal strengths and the known locations;
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39. A method for determining a location of a mobile unit, comprising:
- measuring a wireless signal strength;
comparing the measured wireless signal strength to an environmentally profiled table of wireless signal strengths and known locations of the mobile unit, wherein the environmentally profiled table is selected from a plurality of tables of wireless signal strengths and the known locations of the mobile unit, which tables reflect the influence of environmental factors;
finding a plurality of table entries whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength; and
, determining the location of the mobile unit to be proximate to a spatial average of known locations corresponding to the found plurality of table entries, each corresponding known location having been multiplied by a weighting factor prior to the spatial averaging.
- measuring a wireless signal strength;
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40. A computer-readable medium for creating an environmentally profiled table of wireless signal strengths and known locations using at least two base stations, a first base station at a known first base station location and a second base station, with computer-executable instructions for performing steps, comprising:
- (a) generating the plurality of tables of wireless signal strengths and the known locations;
(b) measuring, at the first base station, a wireless signal strength of the second base station;
(c) comparing the measured wireless signal strength of the second base station to one of the plurality of tables of wireless signal strengths and the known locations;
(d) finding an entry in the one of the plurality of tables of wireless signal strengths and the known locations whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength of the second base station;
(e) determining a location of the first base station with reference to the found table entry;
(f) computing a deviation by comparing the determined location of the first base station to the known first base station location;
repeating steps (a) through (f) for each of the plurality of tables of wireless signal strengths and the known locations; and
, selecting, as the environmentally profiled table, a table of the plurality of tables which minimized the deviation. - View Dependent Claims (41, 42)
- (a) generating the plurality of tables of wireless signal strengths and the known locations;
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43. A computer-readable medium for creating an environmentally profiled table of wireless signal strengths and known locations using at least two base stations, a first base station at a known first base station location and a second base station, with computer-executable instructions for performing steps, comprising:
- (a) generating the plurality of tables of wireless signal strengths and the known locations;
(b) measuring, at the second base station, a wireless signal strength of the first base station;
(c) comparing the measured wireless signal strength of the first base station to one of the plurality of tables of wireless signal strengths and the known locations;
(d) finding an entry in the one of the plurality of tables of wireless signal strengths and the known locations whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength of the first base station;
(e) determining a location of the first base station with reference to the found table entry;
(f) computing a deviation by comparing the determined location of the first base station to the known first base station location;
repeating steps (a) through (f) for each of the plurality of tables of wireless signal strengths and the known locations; and
, selecting, as the environmentally profiled table, a table of the plurality of tables which minimized the deviation. - View Dependent Claims (44, 45)
- (a) generating the plurality of tables of wireless signal strengths and the known locations;
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46. A computer-readable medium having computer-executable instructions for performing steps, comprising:
- measuring a wireless signal strength;
comparing the measured wireless signal strength to an environmentally profiled table of wireless signal strengths and known locations of the mobile unit, wherein the environmentally profiled table is selected from a plurality of tables of wireless signal strengths and the known locations of the mobile unit, which tables reflect the influence of environmental factors;
finding a plurality of table entries whose wireless signal strength is closest, by distance in signal space, to the measured wireless signal strength; and
, determining the location of the mobile unit to be proximate to a spatial average of known locations corresponding to the found plurality of table entries, each corresponding known location having been multiplied by a weighting factor prior to the spatial averaging.
- measuring a wireless signal strength;
Specification