CHAIN ENCODING AND DECODING OF HIGH SPEED OPTICAL SIGNALS WITH MODULATION WITH POWER SHAPING

A method of determining a client bit pattern communicated through an optical communication system, the method comprising detecting a first part of a received symbol from samples comprising several dimensions; correcting bit errors in the first part of the received symbol with a Forward Error Correction, FEC, decoder to a bit error rate of approximately zero; and using the error-free first part to select a value of a second part of the received symbol, wherein the number of bits in the second part of the received symbol is less than the number of bits in the first part of the received symbol, wherein data bits of the client bit pattern were encoded within a sequence of symbols at a transmitter, the encoding including adapting a number of the data bits encoded within each symbol of the sequence to suit an optical channel of the optical communication system and a client bit-rate; power shaping including encoding a power of each symbol of the sequence as a function of the client bit pattern; and using a FEC encoder that employs a FEC overhead of at least 20% of the data bits to generate FEC-encoded power-shaped bits, wherein some portion of the Most Significant Bit (MSB) part of a symbol of the sequence corresponds to the FEC overhead.