A mobile network comprises a cell, with one or more subordinate cells having regions that are each located at least partially within a coverage region of the cell. A base station serving the cell receives a measurement report from a further base station. The further base station is operable for serving one of the subordinate cells. The measurement report indicates a result of a measurement performed by the further base station on an uplink reference signal transmitted by a user equipment. On the basis of the measurement report, the base station controls activity of the subordinate cell.