In a radio communication system where a base station provides blank time slots to avoid inter-cell interference, a decrease in throughput by an excess or shortage of blank time slots is prevented. This invention relates to a radio system that avoids interference in cooperation between base stations by providing blank time slots by a (first) base station. Other (second) base stations detect the number of served terminals affected by interference from the first base station that sets blank time slots, calculate required blank time slots so that the number of required blank time slots will increase with an increase in the number of terminals located in cell edges, and send a notification of the required blank time slots to the first base station. The first base station determines whether system throughput is anticipated to improve, based on the above notifications, and adjusts the length of blank time slots.