Timing division multiplexing is conducted between the cells to avoid intercell interference. Transmission timing in a time slot pattern has a given interval. A base station determines the transmission timing based on measured uplink interference power. For example, an uplink time slot pattern in which the measured uplink interference power is smaller is selected. A downlink time slot pattern is assigned so that a response to HARQ is returned at that timing. If traffic is busy, additional time slot pattern may be assigned. In determination of the traffic volume, for example, the queued buffer size, the number of connected terminals, or the number of connections to a higher-level device can be used. Assignment timing can be an initial setup time, or a fluctuation detection time of a channel which can be realized by collection of report information on a downlink communication quality, periodic monitor of uplink interference information.