Optical coherent receiver with forward error correction

A method for operating an optical coherent receiver comprising a number of decoding blocks, each decoding block being configured to implement an iteration of a forward error correction iterative message-passing decoding algorithm, said number of decoding blocks being distributed into at least two parallel chains of cascaded decoding blocks, wherein said optical coherent receiver also comprises at least one intermediate circuit interposed between said two parallel chains, wherein said method comprises switching said optical coherent receiver between:

• a first operating mode, in which said intermediate circuit is inactive and each one of said two parallel chains separately implements said forward error correction message-passing decoding algorithm on a respective client channel;
• and
• a second operating mode, in which said intermediate circuit is active and said two parallel chains jointly implement said forward error correction message-passing decoding algorithm on a same client channel by cooperating through said intermediate circuit.