Patent ID: 7715852
Filing Date: 2010-05-11
Classification: H04W

Abstract:
1. A location estimation method for locating a mobile station (MS) by a plurality of base stations (BS), comprising: analyzing a geometric distribution of the BSs to provide a list of conditional equations; allocating virtual BSs having virtual distances to the MS to provide constraint equations; and estimating the MS location based on the conditional equations and the constraint equations; wherein analysis of the geometric distribution comprises: transmitting coordinates of each BS to the MS; estimating time-of arrival (TOA) of signals transmitted to or from the BSs to obtain measured distances correspondingly; measuring noise level of each transmission to calculate standard deviations of the measured distances; generating the conditional equations based on the measured distances and the standard deviations; calculating an initial estimate of the MS location based on the standard deviations and coordinates of the BSs; determining the virtual distances based on the initial estimate of the MS location, the coordinates of the BSs and a plurality of virtual coefficients each corresponding to a BS; and rendering a GDOP contour based on the analysis of the geometric distribution, statistically presenting measurement error distribution of the BSs; wherein allocation of the virtual BS comprises: observing peak values distributed in the GDOP contour; and allocating the virtual BSs to the positions where at least one peak value is causally smoothed away.