| 摘要 |
PROBLEM TO BE SOLVED: To enhance the frequency utilization rate for a mobile broadband wireless access. SOLUTION: When the communication propagation environment is excellent, communication is conducted by using only a CH3 with e.g. the 256 QAM method at a transmission rate of e.g. 120 Mbps. When the communication propagation environment gets worse, communication is executed by using CH2 and 3 with e.g. the 16 QAM method at a transmission rate of 120 Mbps. When the communication propagation environment gets worse, communication is executed by using CH1 through CH4 with the QPSK method at a transmission rate of 120 Mbps. In this case, although the bandwidth of one subcarrier is extended, since many numbers of channels are set, total number of the subcarriers can be maintained to be equal to the case with the excellent communication propagation environment, resulting that the transmission rate can be maintained.
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