Abstract: In some embodiments, an apparatus includes an optical transceiver which includes a rate-adaptive forward error correction (FEC) encoder and a rate-adaptive FEC decoder. The rate-adaptive FEC encoder is configured to adjust a number of a set of known symbols associated with a codeword to achieve rate adaption. A length of the codeword is fixed. The rate-adaptive FEC encoder is configured to generate the codeword based on (1) a set of information symbols including the set of known symbols and a set of data symbols, and (2) a fixed number of a set of parity symbols generated using information symbols. The rate-adaptive FEC decoder is configured to receive a set of reliability values associated with a channel word, and expand the set of reliability values to produce an expanded set of reliability values. The rate-adaptive FEC decoder is further configured to decode the expanded set of reliability values.

Abstract: It is disclosed an optical coherent receiver comprising a number of decoding blocks configured to implement iterations of a FEC iterative message-passing decoding algorithm. The decoding blocks are distributed into two (or more) parallel chains of cascaded decoding blocks. The receiver also comprises an intermediate circuit interposed between the two parallel chains. The optical coherent receiver is switchable between (i) a first operating mode, in which the intermediate circuit is inactive and the two parallel chains separately implement the FEC message-passing decoding algorithm on respective client channels; and (ii) a second operating mode, in which the intermediate circuit is active and the two parallel chains jointly implement the FEC message-passing decoding algorithm on a same client channel, by cooperating through the intermediate circuit.

Abstract: In some embodiments, an apparatus includes an optical transceiver which includes a rate-adaptive forward error correction (FEC) encoder and a rate-adaptive FEC decoder. The rate-adaptive FEC encoder is configured to adjust a number of a set of known symbols associated with a codeword to achieve rate adaption. A length of the codeword is fixed. The rate-adaptive FEC encoder is configured to generate the codeword based on (1) a set of information symbols including the set of known symbols and a set of data symbols, and (2) a fixed number of a set of parity symbols generated using information symbols. The rate-adaptive FEC decoder is configured to receive a set of reliability values associated with a channel word, and expand the set of reliability values to produce an expanded set of reliability values. The rate-adaptive FEC decoder is further configured to decode the expanded set of reliability values.

Abstract: Techniques are described for determining pre-compensation parameters to compensate for signal integrity degradation along a signal path. A processor generates a first digital signal and receives a second digital signal. The second digital signal is generated from an optical-to-electrical conversion of a feedback optical signal that is generated from an electrical-to-optical conversion of an electrical signal by an optical module. The processor determines the pre-compensation parameters based on the first and second digital signals.

Abstract: It is disclosed an optical coherent receiver comprising a number of decoding blocks configured to implement iterations of a FEC iterative message-passing decoding algorithm. The decoding blocks are distributed into two (or more) parallel chains of cascaded decoding blocks. The receiver also comprises an intermediate circuit interposed between the two parallel chains. The optical coherent receiver is switchable between (i) a first operating mode, in which the intermediate circuit is inactive and the two parallel chains separately implement the FEC message-passing decoding algorithm on respective client channels; and (ii) a second operating mode, in which the intermediate circuit is active and the two parallel chains jointly implement the FEC message-passing decoding algorithm on a same client channel, by cooperating through the intermediate circuit.

Abstract: Proposed is a method of decoding a differentially encoded PSK modulated optical data signal carrying FEC encoded data values. The optical signal is corrected by an estimated phase offset. From the corrected signal, respective likelihood values for the FEC encoded data values are derived, using an estimation algorithm which accounts for a differential encoding rule used for differentially encoding the optical signal. The derived likelihood values are limited to a predetermined range of values. From the limited likelihood values, FEC decoded data values are derived, using an algorithm which accounts for a FEC encoding rule used for FEC encoding the FEC encoded data values.

Abstract: Proposed is a method of decoding a differentially encoded PSK modulated optical data signal carrying FEC encoded data values. The optical signal is corrected by an estimated phase offset. From the corrected signal, respective likelihood values for the FEC encoded data values are derived, using an estimation algorithm which accounts for a differential encoding rule used for differentially encoding the optical signal. The derived likelihood values are limited to a predetermined range of values. From the limited likelihood values, FEC decoded data values are derived, using an algorithm which accounts for a FEC encoding rule used for FEC encoding the FEC encoded data values.