Optical transmission system, optical transmitting apparatus and optical receiving apparatus

An optical transmission system comprising an optical transmitter that transmits signal light and an optical receiver that receives the signal light,

• wherein the optical transmitter includes:
• a signal coding unit that generates a symbol for transmission by applying a predetermined coding method to a series of m-valued transmission symbols generated from transmission data;
• and
• a transmission unit that generates the signal light by performing optical modulation on the basis of the symbol for transmission, and transmits the generated signal light,
• the optical receiver includes:
• a reception unit that receives the signal light and generates a series of digital signals from the received signal light;
• and
• a digital signal processing unit that detects a coded symbol by applying predetermined digital signal processing to the series of digital signals, decodes the m-valued transmission symbol from the detected coded symbol, and restores the transmission data from the decoded m-valued transmission symbol, and
• an operation based on the predetermined coding method includes an operation of generating an intermediate symbol as the symbol for transmission through nonlinear coding that generates the coded symbol by generating an m-valued intermediate symbol from the m-valued transmission symbol, the nonlinear coding restricting transitions between series of the coded symbols in time series by assigning bit information to a state transition between coded symbols adjacent in time series and making a number of states that each of the coded symbols can take on greater than a number of states of the m-valued transmission symbol, and when the intermediate symbol is generated as the symbol for transmission through the predetermined coding method, the coded symbol is generated from the intermediate symbol through the predetermined digital signal processing.