Patent ID: 7274940

Claim:
A method of determining a location of a plurality of units, each unit being communicatively coupled to at least some of the other plurality of units, wherein at least some of the plurality of units are in communication range with one or more reference units, whose location is at least one of determined and known, said method comprising: sub-dividing the plurality of units into a plurality of sub-nets, wherein each sub-net includes two or more units; measuring, in each of the sub-nets, range information between each of the units in the sub-net and the other units in the sub-net, which are in communication range with the unit, and range information between any reference units and at least one of the units in the sub-net within communication range of the corresponding reference unit; gathering the measured range information in at least a selected one of the units associated with each of the sub-nets; estimating, in the at least selected one of the units associated with each of the sub-nets in which the measured range information was gathered, a location for each of the units in each of the sub-nets, which minimizes any error in the measured ranges between the units within communication range in each of the sub-nets and the measured range between any of the reference units and the corresponding units in the sub-net within communication range of at least one of the reference units.