Abstract: In a first embodiment, a method and apparatus for encoding a first spectral efficiency into a second spectral efficiency; wherein the second spectral efficiency has a higher order than the first spectral efficiency. In a second embodiment, a method and apparatus for achieving at least two spectral efficiencies using a single type of modulation.

Abstract: In a first embodiment, method and apparatus for encoding a first spectral efficiency into a second spectral efficiency; wherein the second spectral efficiency has a higher order than the first spectral efficiency. In a second embodiment, a method and apparatus for achieving at least two spectral efficiencies using a single type of modulation.

Abstract: Quadrature amplitude modulation (QAM) techniques for use in optical systems are described. An optical transceiver may include a modulator configured to modulate data according to a scaled set-partitioning QAM (SP-QAM) scheme. The modulator may be configured to receive a plurality of bits, associate the plurality of bits with a plurality of symbols according to the scaled (SP-QAM) scheme; and transmit the plurality of symbols over an optical channel. A demodulator in an optical receiver may receive the plurality of symbols transmitted over the optical channel and associate the received symbols with a plurality of bits according to the scaled (SP-QAM) scheme; and provide the plurality of bits to a forward error correction decoder.

Abstract: In a first embodiment, method and apparatus for encoding a first spectral efficiency into a second spectral efficiency; wherein the second spectral efficiency has a higher order than the first spectral efficiency. In a second embodiment, a method and apparatus for achieving at least two spectral efficiencies using a single type of modulation.

Abstract: A method, system, and apparatus for encoding a data for transmission across a communication link, the comprising encoding the data into a constellation; wherein the constellation is of a power 2n; wherein n is an odd number; wherein encoding the constellation creates outer constellation points forming a square at an edge of the constellation.

Abstract: Quadrature amplitude modulation (QAM) techniques for use in optical systems are described. An optical transceiver may include a modulator configured to modulate data according to a scaled set-partitioning QAM (SP-QAM) scheme. The modulator may be configured to receive a plurality of bits, associate the plurality of bits with a plurality of symbols according to the scaled (SP-QAM) scheme; and transmit the plurality of symbols over an optical channel. A demodulator in an optical receiver may receive the plurality of symbols transmitted over the optical channel and associate the received symbols with a plurality of bits according to the scaled (SP-QAM) scheme; and provide the plurality of bits to a forward error correction decoder.

Abstract: Quadrature amplitude modulation (QAM) techniques for use in optical systems are described. An optical transceiver may include a modulator configured to modulate data according to a scaled set-partitioning QAM (SP-QAM) scheme. The modulator may be configured to receive a plurality of bits, associate the plurality of bits with a plurality of symbols according to the scaled (SP-QAM) scheme; and transmit the plurality of symbols over an optical channel. A demodulator in an optical receiver may receive the plurality of symbols transmitted over the optical channel and associate the received symbols with a plurality of bits according to the scaled (SP-QAM) scheme; and provide the plurality of bits to a forward error correction decoder.

Abstract: Disclosed are methods for monitoring and measuring Optical Signal-To-Noise Ratios in optical communications systems. One exemplary method involves intentionally inserting zero power symbols into an optical signal stream such that those periods of time in which only zero power symbols are transmitted may be detected and compared with periods of time in which signals modulated with information including both signal and noise are detected such that the OSNR may be determined.

Abstract: Quadrature amplitude modulation (QAM) techniques for use in optical systems are described. An optical transceiver may include a modulator configured to modulate data according to a scaled set-partitioning QAM (SP-QAM) scheme. The modulator may be configured to receive a plurality of bits, associate the plurality of bits with a plurality of symbols according to the scaled (SP-QAM) scheme; and transmit the plurality of symbols over an optical channel. A demodulator in an optical receiver may receive the plurality of symbols transmitted over the optical channel and associate the received symbols with a plurality of bits according to the scaled (SP-QAM) scheme; and provide the plurality of bits to a forward error correction decoder.

Abstract: Disclosed are methods for monitoring and measuring Optical Signal-To-Noise Ratios in optical communications systems. One exemplary method involves intentionally inserting zero power symbols into an optical signal stream such that those periods of time in which only zero power symbols are transmitted may be detected and compared with periods of time in which signals modulated with information including both signal and noise are detected such that the OSNR may be determined.

Abstract: Disclosed are methods for monitoring and measuring Optical Signal-To-Noise Ratios in optical communications systems. One exemplary method involves intentionally inserting zero power symbols into an optical signal stream such that those periods of time in which only zero power symbols are transmitted may be detected and compared with periods of time in which signals modulated with information including both signal and noise are detected such that the OSNR may be determined.

Abstract: Disclosed are methods for monitoring and measuring Optical Signal-To-Noise Ratios in optical communications systems. One exemplary method involves intentionally inserting zero power symbols into an optical signal stream such that those periods of time in which only zero power symbols are transmitted may be detected and compared with periods of time in which signals modulated with information including both signal and noise are detected such that the OSNR may be determined.

Abstract: A computer implemented method for generating soft bit metric information of telecommunications systems employing differential encoding of data.

Abstract: Soft bit metric generation computational complexity can be reduced by identifying and utilizing only the dominant terms in a reliability calculation such as a logarithmic likelihood ratio (LLR). The dominant terms are those terms for which the signs of the x and y components match those of channel outputs of the channel outputs. One technique for identifying the dominant terms is by determining the most likely transitions from two consecutive channel output samples Values for the dominant terms can be estimated by either the joint reliability of two consecutive samples of the in-phase component (x1,x2) or by the joint reliability of two consecutive samples of the quadrature components (y1,y2).

Abstract: Systems, methods, and an article of manufacture for performing serial concatenated decoding are shown and described. The decoding includes monitoring a measure of the number of corrections made to a plurality data blocks during outer decoding and determining whether applying sub-optimal inner decoding would reduce a computational load experienced by a processor performing the serial concatenated decoding when compared to the computation load experienced by the processor when optimal inner decoding is applied.

Abstract: In an optical transmission system which utilizes polarization multiplexing, a receiver includes an adaptive equalizer which is adjusted at turn-up such that two polarization modes at the equalizer output are time aligned. The adaptive equalizer may be reset in a directed manner in response to an indication that one polarization mode is present at both the first and second outputs. Further, the dominant filters taps of the adaptive equalizer are maintained near a middle of a tap index range. The receiver may also include an interpolation function upstream of the adaptive equalizer and a symbol timing error estimation function that feeds a control signal back to the interpolation function, wherein the interpolation function causes the adaptive equalizer function and symbol timing error estimation function to receive an integer number of samples per symbol.

Abstract: Soft bit metric generation computational complexity can be reduced by identifying and utilizing only the dominant terms in a reliability calculation such as a logarithmic likelihood ratio (LLR). The dominant terms are those terms for which the signs of the x and y components match those of channel outputs of the channel outputs. One technique for identifying the dominant terms is by determining the most likely transitions from two consecutive channel output samples Values for the dominant terms can be estimated by either the joint reliability of two consecutive samples of the in-phase component (x1,x2) or by the joint reliability of two consecutive samples of the quadrature components (y1,y2).

Abstract: A computer implemented method for generating soft bit metric information of telecommunications systems employing differential encoding of data.

Abstract: Systems, methods, and an article of manufacture for performing serial concatenated decoding are shown and described. The decoding includes monitoring a measure of the number of corrections made to a plurality data blocks during outer decoding and determining whether applying sub-optimal inner decoding would reduce a computational load experienced by a processor performing the serial concatenated decoding when compared to the computation load experienced by the processor when optimal inner decoding is applied.