Optical transmission distortion compensation device, optical transmission distortion compensation method, and communication device

An optical transmission distortion compensation device comprising:

• an I component compensation unit calculating an I component in which a distortion has been compensated, by forming a first polynomial expressing the distortion of the I component based on an I component and a Q component of a quadrature modulation signal and multiplying each term of the first polynomial by a first coefficient;
• a Q component compensation unit calculating a Q component in which a distortion has been compensated, by forming a second polynomial expressing the distortion of the Q component based on the I component and the Q component of the quadrature modulation signal and multiplying each term of the second polynomial by a second coefficient;
• a coefficient calculation unit calculating the first and second coefficients by comparing outputs of the I component compensation unit and the Q component compensation unit and a known signal;
• and
• a carrier phase recovery unit compensating phase fluctuation of outputs of the I component compensation unit and the Q component compensation unit,
• wherein the coefficient calculation unit calculates the first and second coefficients, using a result from performing a reverse compensation process of a compensation in the carrier phase recovery unit, to an error between an output of the carrier phase recovery unit and the known signal.

An optical transmission distortion compensation device comprising:

• an I component compensation unit calculating an I component in which a distortion has been compensated, by forming a first polynomial expressing the distortion of the I component based on an I component and a Q component of a quadrature modulation signal and multiplying each term of the first polynomial by a first coefficient;
• a Q component compensation unit calculating a Q component in which a distortion has been compensated, by forming a second polynomial expressing the distortion of the Q component based on the I component and the Q component of the quadrature modulation signal and multiplying each term of the second polynomial by a second coefficient;
• a coefficient calculation unit calculating the first and second coefficients by comparing outputs of the I component compensation unit and the Q component compensation unit and a known signal;
• and
• an adaptive equalization unit performing an equalization process to the quadrature modulation signal;
• and
• a phase fluctuation compensation unit performing a compensation process to the quadrature modulation signal,
• wherein the I component compensation unit and the Q component compensation unit are provided at a subsequent stage of the adaptive equalization unit and the phase fluctuation compensation unit, and
• the adaptive equalization unit and the phase fluctuation compensation unit calculate a filter coefficient and a compensation amount for the equalization process and the compensation process, using a known signal to which an IQ distortion evaluated from a calculation result of the coefficient calculation unit has been added.

An optical transmission distortion compensation method performed by an optical transmission distortion compensation device compensating a distortion in a receiving device, comprising:

• calculating an I component in which a distortion has been compensated, by forming a first polynomial expressing the distortion of the I component based on an I component and a Q component of a quadrature modulation signal and multiplying each term of the first polynomial by a first coefficient;
• calculating a Q component in which a distortion has been compensated, by forming a second polynomial expressing the distortion of the Q component based on the I component and the Q component of the quadrature modulation signal and multiplying each term of the second polynomial by a second coefficient;
• and
• calculating the first and second coefficients by comparing the I component and the Q component in which the distortion have been compensated and a known signal.