Alignment detection by full and partial FEC decoding

A method for finding an alignment of a code block by attempting to fully decode or partially decode one or more data windows in a data stream, wherein the data stream includes a plurality of codewords encoded based on a particular error control coding method, and each codeword has a predetermined size, the method comprising:

• selecting a first data point in the data stream;
• attempting to decode by a forward error correction (FEC) decoder a first data window of the predetermined size starting from the first data point based on the particular error control coding method;
• determining whether a valid codeword can be identified by attempting to decode the first data window;
• and
• in response to determining that a valid codeword can be identified by attempting to decode the first data window,
• determining that an alignment of the codeword with the first data window is found;
• and
• continuing decoding subsequent codewords based on the alignment;
• in response to determining that a valid codeword is not identified by attempting to decode the first data window,
• selecting a second data point in the data stream;
• and
• attempting to decode a second data window starting from the second data point based on the particular error control coding method.

A forward error correction (FEC) decoder having an acquisition mode and a lock mode, wherein:

• when the FEC decoder is in the lock mode, the decoder knows borders of each codeword in a data stream, and the decoder is configured to decode each codeword in the data stream based on a particular error control coding method;
• when the FEC decoder is in the acquisition mode, the FEC decoder does not know the borders of each codeword in the data stream, and the FEC decoder is configured to:
• find an alignment of a code block in the data stream by attempting to fully decode or partially decode one or more data windows of a predetermined size in the data stream, the predetermined size being a size of each codeword, comprising:
• selecting a first data point in the data stream;
• attempting to decode a first data window of the predetermined size starting from the first data point based on the particular error control coding method;
• determining whether a valid codeword can be identified by attempting to decode the first data window;
• in response to determining that a valid codeword can be identified by attempting to decode the first data window,
• determining that an alignment of the code block is found;
• and
• switching the FEC decoder to the lock mode;
• in response to determining that the decoded data window is not a valid codeword,
• selecting a second data point in the data stream;
• and
• attempting to decode a second data window of the predetermined size starting from the second data point based on the particular error control coding method.