| 摘要 |
<P>PROBLEM TO BE SOLVED: To maximize transmission line capacity and to improve a communication quality by determining an optimal modulated multilevel number corresponding to a dynamic change in tertiary mutual modulation distortion. <P>SOLUTION: A mutual modulation distortion detecting part 23a calculates a spectrum for each frequency from a photo-current RF signal, extracts the spectrum of a frequency located in the center of all bands and detects the distortion component information of the mutual modulation distortion. An evaluation function arithmetic part 23b operates an evaluation function on the basis of the distortion component information and calculates an optimal optical modulation factor mopt and entire transmission line capacity Ct including an optical fiber transmission line and a wireless transmission line for each modulation multilevel number. An optimal modulation multilevel number determining part 25a determines the optimal modulation multilevel number taking the maximum value of the entire transmission line capacity Ct. An RF modulation part 25b generates an RF modulated signal by applying RF modulation to transmission data while using the optimal modulation multilevel number. An optical signal transmitting part 26 generates and transmits an optical RF modulated signal by controlling the electric/optic conversion of the RF modulation signal while using the optimal optical modulation factor mopt. <P>COPYRIGHT: (C)2003,JPO |
