Patent ID: 7742773

Claim:
A method of determining the floor of a building, on which a first person carrying a first wireless communication device is located, using a second wireless communication device, the method comprising the steps of: (a) determining, utilizing electronics of a first wireless communication device, an (x,y) position of the first wireless communication device; (b) determining, utilizing electronics of a second wireless communication device, an (x,y) position of the second wireless communication device; (c) determining, utilizing electronics of the first wireless communication device or electronics of the second wireless communication device, a distance between the first wireless communication device and the second wireless communication device; (d) communicating, from the second wireless communication device to the first wireless communication device, the determined (x,y) position of the second wireless communication device; and (e) determining, utilizing electronics of the first wireless communication device, a relative elevational differential between the first wireless communication device and the second wireless communication device based on, (i) the determined (x,y) positions of the first and second wireless communication devices, and (ii) the determined distance between the first and second wireless communication devices; (f) determining a number of floors corresponding to the relative elevational differential between the first wireless communication device and the second wireless communication device; (g) wherein the determined relative elevational differential is an absolute magnitude, the method further comprising the step of determining, separately from the determination of the relative elevational differential, the direction, relative to the first wireless communication device, in which the determined relative elevational differential is to be applied.