Disclosed is a method and apparatus for correcting clocks for a plurality of local transmitters. In one embodiment, the functions implemented include: receiving base station time from a plurality of local transmitters; assigning each local transmitter of the plurality of local transmitters to at least one subset of a plurality of subsets, wherein each subset corresponds to a single base station, and wherein each local transmitter in a particular subset receives time from a base station corresponding to the subset; selecting a single subset of local transmitters as a reference subset of local transmitters, the reference subset corresponding to a reference base station, each non-reference subset corresponding to a non-reference base station; determining a time difference between the reference base station and each of the non-reference base stations based on time received from one or more local transmitters that belong in more than one of the subsets; and transmitting the time difference to respective non-reference subsets of local transmitters.