Patent ID: 7424300

Claim:
A method for locating within an area a mobile unit arranged for a wireless radio communications with fixed devices, wherein location is determined by comparing radio signal characteristics between said mobile unit and said fixed devices to a database relating said radio signal characteristics to location within said area, wherein at least one portion of said area includes a barrier, comprising; assigning the at least one portion including the barrier with a probability of zero; taking sequential samples of said radio signal characteristics; for each sample of said radio signal characteristics determining two or more possible initial locations for said mobile unit and assigning a location probability that said mobile unit is at each of said possible locations, each location probability modified to account for the barrier; for each possible location determined using a sample after an initial sample, determining a movement probability that a mobile unit has moved from each possible location for one or more prior samples to said possible location, said movement probability being derived from proximity of said possible location for said one or more prior samples and said possible locations for said current sample, wherein said movement probability is modified by factors including at least the probability of zero for the at least one portion including the barrier of the mobile unit between said possible location for said one or more prior samples and said possible location for a current sample; and selecting a location for said mobile unit as the most probable location for said current sample based on a combination of said location and movement probabilities.