| 摘要 |
<P>PROBLEM TO BE SOLVED: To increase a transmission efficiency in a communication system that uses orthogonal frequency division multiple/code spread (OFDM-CDM) transmission system. <P>SOLUTION: A spread modulator 1 spreads a signal sequence. A sub-carrier modulator 2 uses an output from the spread modulator 1 to frequency-modulate a plurality of sub-carriers that have different frequencies from each other. An adder 3 combines each of the modulated sub-carriers. A guard interval control portion 23 decides a length of a guard interval depending on the maximal transmission delay difference in a line between a transmission device and a reception device. At every symbol period, a guard interval inserter 21 inserts a guard interval into the signal sequence in accordance with control by the guard interval control portion 23. A gain adjuster 22 multiplies a transmission signal by a gain factor that corresponds to the inserted guard interval. <P>COPYRIGHT: (C)2010,JPO&INPIT |
