Importance

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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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First Claim