A communication system and an operating method thereof are provided. The communication system includes at least one user equipment, at least one remote radio head (RRH), a measuring unit, a set determining unit and an antenna selecting unit. The RRH is electrically connected to a plurality of antennas. The measuring unit is for controlling a measurement of a signal strength of the at least one user equipment. The set determining unit is used for selecting one of a plurality of antenna configuration sets according to the signal strength for the at least one user equipment. Each of the antenna configuration sets includes a plurality of antenna configurations. Each of the antenna configurations is composed of P of a plurality of antennas. The antenna selecting unit is used for allocating one of the antenna configurations from the antenna configuration set which is selected for the at least one user equipment.