1. 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 locations are at least one of determined and known, said method comprising: measuring range information between each of the units and any reference units within communication range of one another; establishing a possible location area for each of the units including a plurality of possible initial location estimates; selecting an initial location estimate for each of the units, whose location is not known, from an area corresponding to the possible location area; estimating a location for each of the units, which minimizes an error value, based on the difference between the measured range values and a range calculated from the estimated location values; repeating, at least once, the selection of initial location estimates using a different set of initial location estimates for each of the units from the plurality of possible initial location estimates and the estimation of a location for each of the units, which minimizes an error value; and selecting the set of location estimates from the repeated estimations having the smallest minimized error value.