<p>An assigning section (101) in a base station unit sets the transmission rate of a transmission signal to a communication terminal according to a DRC signal transmitted therefrom. A power margin information detecting section (117) detects power margin information from a demodulated signal generated by a demodulating section (115), and a power setting section (118) sets a minimum transmission power value so that the characteristics of a received signal at each communication terminal satisfies the desired quality using the power margin information. The base station unit transmits a signal at the set transmission rate to the communication terminal using the set transmission power value. The interference with a communication terminal performing adaptive modulation communication with another base station unit and the interference with a communication terminal performing adaptive modulation communication with the base station at the same time can thereby be suppressed.</p>
