Receiving apparatus and setting method

A receiving apparatus comprising:

• a first processor configured to perform a compensation, in a perturbation back-propagation (PBP) scheme, waveform degradation of a received optical signal due to a nonlinear optical effect by traveling an optical transmission line;
• a memory to store gamma coefficients corresponding to optical powers, respectively, of a channel on the optical transmission line as reception quality parameters of the PBP scheme;
• and
• a second processor coupled to the memory and the second processor configured to,
• perform a plurality of measurements of reception quality of the received optical signal for a plurality of different gamma coefficients in the PBP scheme, respectively,
• specify a gamma coefficient from among the plurality of different gamma coefficients in the plurality of measurements at which a measured reception quality is at least larger than a reference reception quality to control the compensation, and
• update the gamma coefficients in the memory with the specified gamma coefficient corresponding to the measured reception quality as an updated gamma coefficient to update the reception quality parameters of the PBP scheme and update the reference reception quality with the measured reception quality corresponding to the specified gamma coefficient;
• and
• wherein the specified gamma coefficient is specified when determined that a differential value between a current measured reception quality and a comparative reception quality exceeds a threshold.