Provided is a wireless communication system including a first communication device configured to perform spectral shaping on a frequency signal and transmit the signal, and a second communication device configured to receive the signal transmitted by the first communication device, and the second communication device includes: a frequency averaging unit configured to dividing information on transmission power gains in all the discrete frequencies into blocks by a plurality of discrete frequencies, information being necessary for the first communication device to perform the spectral shaping; a quantizing unit configured to quantize representative values of the blocks; and a transmitting unit configured to transmit the quantized signals.