A timing offset value between at least one macro node and a common global navigation satellite system, GNSS, derived reference time is measured. The timing offset value is transmitted to at least a cell node that does not have a GNSS reference for transmission timing adjusting at the cell node. In some embodiments, where no small cell in a cluster has a GNSS reference time, a timing of a macro base station is used as a reference for synchronizing small cells in the cluster.