To increase an efficiency of frequency usage and a transmission speed while communication quality is kept.

According to a condition of propagation paths, switching is carried out adequately in a variety of transmission, such as (spacial multiplexing) transmission of different information (transmission signal A ≠transmission signal B) from a plurality of antennae 106 and 116 in the same frequency, (frequency multiplexing) transmission of different information (transmission signal A ≠ transmission signal B) from the plurality of antennae 106 and 116 in different frequencies, and (spacial diversity) transmission of the same information (transmission signal A = transmission signal B) from the plurality of antennae 106 and 116 in different frequencies. In this case, each frequency with no risk of interference is detected from a plurality of usable frequencies, and each transmission frequency for the antennae 106 and 116 is set from the detected frequencies.

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