The present disclosure relates to a radio base station serving a user equipment in a first radio cell of a mobile communication system. The radio base station comprises processing circuitry which determines that a neighbor radio base station does not provide a beamformed reference signal to the user equipment. The neighbor radio base station controls the transmission in its neighbor radio cell of an omni-directional reference signal and the beamformed reference signal. A transmitter transmits a reference signal request to the neighbor radio base station. The reference signal request requests the neighbor radio base station to provide the beamformed reference signal to the user equipment. A receiver receives from the neighbor radio base station a reference signal request response, including information on the transmission of the requested beamformed reference signal. The transmitter transmits a notification to the user equipment, comprising information on the requested beamformed reference signal.