Method and system for determining user location in a wireless communication network
First Claim
1. A method for locating an addressable receiver of electromagnetic radiation relative to locations of a plurality of addressable sources of the electromagnetic radiation in a wireless communication network, the method comprising the steps of:
- establishing a plurality of radio maps having coordinates corresponding to locations in space at which a calibration signal strength from each of a set of the plurality of addressable sources is measured, each of said radio maps having stored at said coordinates thereof a probability distribution of said calibration signal strength from a corresponding one of said set of said plurality of addressable sources;
measuring a received signal strength of each of said set of addressable sources at the addressable receiver;
compensating said received signal strength measurement of each of said set of addressable sources for temporal variations therein; and
identifying one of said coordinates of said plurality of radio maps corresponding to a location in space at which said compensated signal strength measurement of said set of addressable sources would be measured with maximum probability given said probability distribution of calibration signal strength of said set of addressable sources thereat, said identified coordinate being a discrete-space estimate of the location of the addressable receiver.
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Abstract
In a wireless communication network, the location of an addressable receiver relative to the locations of a plurality of addressable sources of electromagnetic radiation is found using probabilistic models of the signal strength measured at the addressable receiver. The inventive method provides location determination on a finer spatial scale than was heretofore available. A region of interest is calibrated via a discrete-space radio map storing probability distributions of received signal strength at the measurement locations. The stored probability distributions are compensated for temporal variability and biases, such as through temporal correlations of the sampled received signal strength. A measurement of the signal strength at the addressable receiver from each of the plurality of addressable sources is used in conjunction with the discrete-space radio map to identify one of the coordinates thereof that maximizes the conditional probability P(x|s), where x is the radio map location and s is a vector of measured signal strengths. Small spatial scale variability can be compensated for using a perturbation technique. The method further implements a continuous-space estimator to return an estimated user location that falls between discrete-space radio map locations.
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Citations
39 Claims
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1. A method for locating an addressable receiver of electromagnetic radiation relative to locations of a plurality of addressable sources of the electromagnetic radiation in a wireless communication network, the method comprising the steps of:
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establishing a plurality of radio maps having coordinates corresponding to locations in space at which a calibration signal strength from each of a set of the plurality of addressable sources is measured, each of said radio maps having stored at said coordinates thereof a probability distribution of said calibration signal strength from a corresponding one of said set of said plurality of addressable sources;
measuring a received signal strength of each of said set of addressable sources at the addressable receiver;
compensating said received signal strength measurement of each of said set of addressable sources for temporal variations therein; and
identifying one of said coordinates of said plurality of radio maps corresponding to a location in space at which said compensated signal strength measurement of said set of addressable sources would be measured with maximum probability given said probability distribution of calibration signal strength of said set of addressable sources thereat, said identified coordinate being a discrete-space estimate of the location of the addressable receiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for locating an addressable source of electromagnetic radiation relative to locations of a plurality of addressable receivers of the electromagnetic radiation in a wireless communication network, the method comprising the steps of:
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establishing a plurality of radio maps having coordinates corresponding to locations in space at which a calibration signal strength from the addressable source is measured at each of a set of the plurality of addressable receivers, each of said radio maps having stored at said coordinates thereof a probability distribution of said calibration signal strength measured at a corresponding one of said set of said plurality of addressable receivers;
measuring a received signal strength of the addressable source at each of said set of addressable receivers;
compensating said received signal strength measurement of the addressable source at each of said set of addressable receivers for temporal variations therein; and
identifying one of said coordinates of said plurality of radio maps corresponding to a location in space at which said compensated signal strength of the addressable source would be measured at said set of addressable receivers with maximum probability given said probability distribution of calibration signal strength of said addressable source at said set of addressable receivers, said identified coordinate being a discrete-space estimate of the location of the addressable source. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A system for locating a user in a wireless communication network comprising:
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a computing device having a wireless network interface card installed therein, said wireless network interface card adapted to the wireless communication network;
a plurality of access points for communicating signals between said wireless network interface card and the wireless communication network;
a radio map builder for establishing a plurality of radio maps having coordinates corresponding to locations in space at which a calibration signal strength as measured between each of a set of said plurality of access points and said wireless network interface card, each of said radio maps having stored at said coordinates thereof a probability distribution of said calibration signal strength for each of said plurality of access points;
a radio map database for storing said plurality of radio maps therein;
a correlation modeler for performing time-series analysis on said calibration signal measurement and compensating said calibration signal measurement for temporal variations therein;
a correlation handler for compensating a location determination signal between said wireless network interface card and each of said access points; and
a discrete-space estimator for providing a discrete-space estimate of the user location by identifying one of said coordinates of said plurality of radio maps corresponding to a location in space at which said compensated location determination signal would be measured with maximum probability given said probability distribution of calibration signal strength measurements between said wireless network interface card and said plurality of access points stored in said corresponding radio maps. - View Dependent Claims (36, 37, 38, 39)
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Specification