Abstract: Consistent with the present disclosure, an optical communication system is provided in which data is carried over optical signals including subcarriers. The subcarriers may be modulated with the standard modulation formats noted above, but the modulation formats are selectively assigned to the subcarriers, such that some subcarriers are modulated with different standard modulation formats than others. As used herein, a “standard modulation format” is one of BPSK, and n-QAM, where n is an integer greater than one. Such n-QAM modulation formats include of 3-QAM, 4-QAM (QPSK), 8-QAM, 16-QAM, 64-QAM, 128-QAM, and 256-QAM. By selecting the number of subcarriers and the types of modulation formats employed, an optical signal with an effective SE that is between that of the standard modulation formats can be generated for transmission over a distances that more closely matches the link distance.

Abstract: Consistent with the present disclosure, an optical communication system is provided in which data is carried over optical signals including subcarriers. The subcarriers may be modulated with the standard modulation formats noted above, but the modulation formats are selectively assigned to the subcarriers, such that some subcarriers are modulated with different standard modulation formats than others. As used herein, a “standard modulation format” is one of BPSK, and n-QAM, where n is an integer greater than one. Such n-QAM modulation formats include of 3-QAM, 4-QAM (QPSK), 8-QAM, 16-QAM, 64-QAM, 128-QAM, and 256-QAM. By selecting the number of subcarriers and the types of modulation formats employed, an optical signal with an effective SE that is between that of the standard modulation formats can be generated for transmission over a distances that more closely matches the link distance.

Abstract: Various apparatus and methods may use iterative de-mapping/decoding to on received symbol estimates corresponding to interleaved coded modulation (ICM) using low-density parity check convolutional coding (LPDC-CC). The iterative de-mapping/decoding, may take the form of a multi-stage feed-forward arrangement that may include multiple identically designed stages, and the stages may use parallelism to increase speed and efficiency.

Abstract: A processor circuit is provided in a coherent optical receiver module. The processor receives a series of electrical signals over a time period, representative of a series of optical signals received at instants of time within the time period. Each of the electrical signals is indicative of a respective one of a plurality of points on an IQ plane, each of the points being spaced from one of a plurality of predetermined points in the IQ plane by a corresponding one of a plurality of distortion values. In addition, the processor circuit calculates one or more perturbative coefficients based on one or more of the distortion values and determines data from the series of electrical signals based on the perturbative coefficient.

Abstract: Various apparatus and methods may use iterative de-mapping/decoding to on received symbol estimates corresponding to interleaved coded modulation (ICM) using low-density parity check convolutional coding (LPDC-CC). The iterative de-mapping/decoding, may take the form of a multi-stage feed-forward arrangement that may include multiple identically designed stages, and the stages may use parallelism to increase speed and efficiency.

Abstract: Consistent with the present disclosure, an optical communication system is provided in which data is carried over optical signals including subcarriers. The subcarriers may be modulated with the standard modulation formats noted above, but the modulation formats are selectively assigned to the subcarriers, such that some subcarriers are modulated with different standard modulation formats than others. As used herein, a “standard modulation format” is one of BPSK, and n-QAM, where n is an integer greater than one. Such n-QAM modulation formats include of 3-QAM, 4-QAM (QPSK), 8-QAM, 16-QAM, 64-QAM, 128-QAM, and 256-QAM. By selecting the number of subcarriers and the types of modulation formats employed, an optical signal with an effective SE that is between that of the standard modulation formats can be generated for transmission over a distances that more closely matches the link distance.

Abstract: Methods and systems are disclosed including receiving, with a processor circuit in a coherent optical receiver module, a series of electrical signals over a time period, representative of a series of optical signals received at instants of time within the time period, each of the electrical signals being indicative of a respective one of a plurality of points on an IQ plane, each of the points being spaced from one of a plurality of predetermined points in the IQ plane by a corresponding one of a plurality of distortion values; calculating, with the processor circuit, one or more perturbative coefficients based on one or more of the distortion values; and determining, with the processor circuit, data from the series of electrical signals based on the perturbative coefficient.