Apparatus and method for determining coefficients of fixed equalizer

An apparatus for determining coefficients of a fixed equalizer, the fixed equalizer being applicable to performing fixed equalization on an optical communications system, the apparatus comprising:

• a memory that stores a plurality of instructions;
• and
• a processor coupled to the memory and configured to:
• determine coefficients of an adaptive equalizer according to an output signal of the optical communications system:
• perform Fourier transform on at least a part of the coefficients of the adaptive equalizer to obtain frequency responses of the at least the part of the coefficients:
• calculate coefficients of the fixed equalizer according to the frequency responses of the at least the part of the coefficients of the adaptive equalizer;
• and
• re-obtain, coefficients of the adaptive equalizer according to an output signal of the optical communications system, recalculate coefficients of the fixed equalizer according to the re-obtained coefficients of the adaptive equalizer, and update the coefficients of the fixed equalizer according to the recalculated coefficients of the fixed equalizer while the optical communications system is in use.

A method for determining coefficients of a fixed equalizer, the fixed equalizer being applicable to performing fixed equalization on an optical communications system, the method comprising:

• determining coefficients of an adaptive equalizer according to an output signal of the optical communications system:
• performing Fourier transform on at least a part of the coefficients of the adaptive equalizer to obtain frequency responses of the at least the part of the coefficients;
• and
• calculating coefficients of the fixed equalizer according to the frequency responses of the at least the part of the coefficients of the adaptive equalizer:
• wherein, the adaptive equalizer is a 4×4 Multiple Input Multiple Output (MIMO) adaptive equalizer or a 2×4 MIMO adaptive equalizer, and
• the performing Fourier transform on the at least the part of the coefficients of the adaptive equalizer to obtain frequency responses of the at least the part of the coefficients and calculating coefficients of the fixed equalizer according to the frequency responses of the at least the part of the coefficients of the adaptive equalizer comprise:
• performing Fourier transform according to four main diagonal coefficients and four secondary diagonal coefficients in 2×4 coefficients obtained by transforming 4×4 coefficients of the 4×4 MI MO adaptive equalizer or 2×4 coefficients of the 2×4 MI MO adaptive equalizer to obtain four main diagonal frequency domain coefficients and four secondary diagonal frequency domain coefficients;
• and
• calculating the coefficients of the fixed equalizer according to the four main diagonal frequency domain coefficients, a first weight of the main diagonal frequency domain coefficients, the four secondary diagonal frequency domain coefficients and a second weight of the secondary diagonal frequency domain coefficients.

A method for determining coefficients of a fixed equalizer, the fixed equalizer being applicable to performing fixed equalization on an optical communications system, the method comprising:

• determining coefficients of an adaptive equalizer according to an output signal of the optical communications system;
• performing Fourier transform on at least a part of the coefficients of the adaptive equalizer to obtain frequency responses of the at least the part of the coefficients;
• calculating coefficients of the fixed equalizer according to the frequency responses of the at least the part of the coefficients of the adaptive equalizer;
• and
• re-obtaining, coefficients of the adaptive equalizer according to an output signal of the optical communications system, recalculating coefficients of the fixed equalizer according to the re-obtained coefficients of the adaptive equalizer, and updating the coefficients of the fixed equalizer according to the recalculated coefficients of the fixed equalizer while the optical communications system is in use.