Patent ID: 8086248
Filing Date: 2011-12-27
Classification: G01S,H04W

Abstract:
1. An apparatus for estimating location of an object by monitoring radio packets, said packets being periodically transmitted by a plurality of radio beacons deployed at known positions over a location estimation area, said packets comprising (i) an identifier unique to a given one of the beacons and (ii) a unique sequence number, said apparatus comprising: a plurality of antennas, each of said antennas having an output; a memory; and at least one processor, coupled to said memory and said antenna outputs, said processor being operative to carry out the following steps for k=1 to K: said processor being further operative to estimate the location as an approximate intersection of spheres with radii {circumflex over (d)} wherein K is at least two in a case where said object is constrained to move in a single spatial dimension, K is at least three in a case where said object is constrained to move in two spatial dimensions, and K is at least four in a case where said object is free to move in three spatial dimensions, and wherein K comprises a number of said beacons that have successfully transmitted one or more of said radio packets to the object during the time window T.