Optical transmitter, optical communication system, and optical communication method

An optical communication system, comprising:

• an optical transmitter configured to send out a modulated optical signal to an optical transmission medium;
• and
• an optical receiver configured to receive the modulated optical signal propagated through the optical transmission medium,
• wherein the optical transmitter includes
• an encoder configured to encode digital signals to be transmitted under a predetermined transmission condition over an optical carrier wave by using one of a plurality of encoding methods,
• an encoding control unit configured to select a predetermined encoding method corresponding to the predetermined transmission condition from among the plurality of encoding methods and causing the encoder to operate in accordance with the predetermined encoding method,
• a mapping unit configured to map output bit signals output from the encoder to modulation symbols, and
• an optical modulation unit configured to modulate the optical carrier wave based on symbol signals output from the mapping unit and outputting an optical modulated signal,
• wherein the optical receiver includes
• a photoelectric conversion unit configured to receive and convert the optical modulated signal into an electrical signal and outputting a received signal,
• a demapping unit configured to demap the received signal and output a received bit signal,
• a decoder configured to receive input of the received bit signal and decode the received bit signal by using one of a plurality of decoding methods, and
• a decoding control unit configured to select a predetermined decoding method from among the plurality of decoding methods and cause the decoder to operate in accordance with the predetermined decoding method.

An optical communication method comprising:

• encoding digital signals to be transmitted under a predetermined transmission condition over an optical carrier wave by selecting a predetermined encoding method corresponding to the predetermined transmission condition;
• generating symbol signals by mapping encoded bit signals to modulation symbols;
• and
• generating an optical modulated signal obtained by modulating the optical carrier wave based on the symbol signals.