In a radio-communication system and a radio station, one or more
subcarriers are grouped, and the maximum bit number per symbol of the
modulation method used for each subcarrier is determined for each group
and shared between a transmitting station and a receiving station. The
transmitting station divides and allocates a coded signal to subcarriers
in accordance with the bit number per symbol, modulates each of the
allocated signals by a predetermined modulation method, and transmits the
modulated signals. The receiving station demodulates the received signal
by the predetermined modulation method, adds a signal having zero
likelihood when the bit number per symbol of a modulation method for
demodulation is different from a maximum bit number, and decodes the
demodulated signal by summarizing the demodulated results.