A control system connected to a plurality of array antenna performs beamforming. The control system comprises a beam radiation controller for requesting a predetermined first antenna group to radiate beams and requesting a second antenna group including the first antenna group to radiate beams to an optimized sector, a beam receiver for receiving response beams from the first antenna group and the second antenna group, and a sector selector for setting up an optimized sector based on the received beams for the first antenna group, and transmitting information on the optimized sector to the beam radiation controller in order to control the second antenna group to radiate beams to the optimized sector.