Optical receiver, optical reception method, and optical communication system

An optical communication system comprising:

• an optical transmitter that transmits an optical modulation signal;
• and
• an optical receiver that receives the optical modulation signal, demodulates the optical modulation signal into a baseband signal that is an electrical signal, and decodes a received symbol acquired by converting the baseband signal,
• wherein the optical receiver includes:
• an analog-to-digital converter that converts the baseband signal into a digital signal of which the number of samples per received symbol is M/N (samples/symbol), M and N being positive integers, M/N being not an integer, and “M >N” being satisfied;
• and
• an adaptive equalization processing unit that executes an equalization operation set in advance to output the received symbol on a basis of the digital signal of which the number of samples per received symbol is M/N (samples/symbol) and at least one tap coefficient used for equalization of a signal, the at least one tap coefficient being updated in any sampling period.