| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an OFDM transmission system improving an SNR without exceeding the upper-limit specified value of a mean sending power in a sub-channel band when reducing a transfer rate. <P>SOLUTION: Modem devices A and B are connected to a power-line transmission line 1. In a transmission section 2 for the modem device A, 12 represents a serial-parallel conversion section, is controlled by a transmission control section 5, uses at least a partial sub-channel and series-parallel converts transmission data at a symbol unit by using at least the partial symbol period of the used sub-channel. The transmission control section 5 lowers the rate of the used sub-channel and/or the rate of the used symbol period in response to a setting lowering the transfer rate. An amplifying section 18 raises a transmission level in response to the rate of the used symbol period when a gain is controlled by the transmission control section 5. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
