Patent ID: 7885545

Claim:
A dispersion compensation method compensating for chromatic dispersion occurring in a channel transmitting therein a signal in which optical signals having different bit rates are wavelength-multiplexed, comprising: providing a compensation node for each predetermined number of in-line repeaters of a plurality of predetermined numbers of in-line repeaters; carrying out dispersion compensation in common for the different bit rates in the in-line repeaters; carrying out wavelength demultiplexing on the optical signals for the respective different bit rates in the compensation node provided for each predetermined number of in-line repeaters; performing per-bit-rate dispersion compensating of the optical signals for setting an optimum dispersion compensation value for the optical signal at each bit rate and carrying out dispersion compensation for each bit rate; carrying out wavelength multiplexing of the optical signals each having undergone the dispersion compensation by means of the per-bit-rate dispersion compensating; and carrying out optical adding/dropping or optical cross-connect for each of different bit rates, wherein: the setting sets an optimum residual dispersion amount for each bit rate at a reproduction repeating span when the optical adding/dropping or optical cross-connect is carried out for each of the different bit rates to a value in proportion to the number of repeater spans from a transmission end with respect to an optimum residual dispersion reference amount for a maximum transmission distance at the corresponding bit rate.