Apparatus and method for beamforming with limited feedforward channel in multiple input multiple output wireless communication system

An apparatus for a base station in a Multiple Input Multiple Output (MIMO) wireless communication system, the apparatus comprising:

• a first calculator configured to repeatedly calculate, using information of downlink channel matrixes of spatial multiple access user terminals, downlink beamforming vectors of the user terminals to calculate the optimal beamforming vectors for the user terminals;
• a quantizer configured to quantize the downlink beamforming vectors in order to transmit information of the downlink beamforming vectors;
• a control channel transmitter configured to feed forward information of the quantized downlink beamforming vectors to the user terminals over a control channel;
• a second calculator configured to calculate the final downlink beamforming vectors of the user terminals in consideration of an error due to the quantization;
• and
• a beamforming transmitter configured to sum the beamformed TX signals of the user terminals in accordance with the final downlink beamforming vectors and transmit the summed TX signals through a plurality of TX antennas.