A control circuit, comprising a processor, and a computer readable medium is described. The computer readable medium stores logic that causes the processor to analyze performance data of a link carrying data encoded in a first modulation format with a degradation prediction algorithm to determine a predicted level of degradation of the link. The processor provides first control signals to a transmitter block, and second control signals to a receiver block based upon the predicted level of degradation of the link over time. The first control signals cause the transmitter block to encode data to be transmitted over the link in a second modulation format. The second control signals cause the receiver block to decode data received from the link using the second modulation format. The first and second modulation formats conform to requirements of a same m-quadrature amplitude modulation protocol.

An apparatus comprising a control circuit providing a variable control signal, and a transmitter. The transmitter operable to provide a modulated optical signal including a plurality of optical subcarriers. One of the plurality of optical subcarriers carries a sequence of modulation symbols. The sequence of modulation symbols includes modulation symbols that are output with a variable transmission frequency in accordance with a transmission probability distribution that is variable based on the control signal.

An apparatus comprising a control circuit providing a variable control signal, and a transmitter. The transmitter operable to provide a modulated optical signal including a plurality of optical subcarriers. One of the plurality of optical subcarriers carries a sequence of modulation symbols. The sequence of modulation symbols includes modulation symbols that are output with a variable transmission frequency in accordance with a transmission probability distribution that is variable based on the control signal.

A transmitter block, comprising an optical source, a modulator, a transmission circuit and a control circuit. The optical source has a laser providing an optical signal. The modulator is configured to encode data into the optical signal using an m-quadrature amplitude modulation format. The transmission circuit has circuitry to receive data to be encoded into the optical signal. The transmission circuit has at least one drive circuit supplying driver signals to the modulator to cause the modulator to encode data into the optical signal using the m-quadrature amplitude modulation format. The control circuit supplies control signals to the transmission circuit to cause the transmission circuit to change the m-quadrature amplitude modulation format from a first m-quadrature amplitude modulation format to a second m-quadrature amplitude modulation format based upon predicted degradation of a link to receive modulated data from the modulator.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

A set of media channel (MCh) widths is determined for an optical network. Based on a topology of the network, a first set of original MCh widths are computed for tentative use in the optical network, the first set of original MCh widths defining a target spectral efficiency. A reduced set of new MCh widths are generated from the first set of MCh widths by respectively mapping each of the original MCh widths of the first set of original MCh widths to a corresponding, or respective, new MCh width. An optimization algorithm is used in an example embodiment to facilitate the mapping.

Systems and methods for constellation shaping using low rate loss bit-level distribution matchers include receiving blocks of input bits and, for each input block of a predetermined size, assigning a respective codeword of a predetermined output block size. The number of bits of a given bit value in the codeword is dependent on a predetermined target probability distribution. A one-to-one mapping exists between each possible combination of input bits and a codeword for input blocks containing the combination. Some codewords include a number of bits having the given bit value that is different than the predetermined target probability distribution, but an average number of bits having the given bit value in the available codewords meets the predetermined target probability distribution. The disclosed methods result in more available codewords and a lower rate loss than in bit-level distribution matchers with a constant modulus, while achieving similar shaping.

A network system includes a plurality of transmission devices, each of which being provided with a wavelength selective switch including a wavelength filter, configured to transmit an optical signal for each channel; and a management device configured to manage the plurality of transmission devices. The wavelength selective switch configured to enable band setting that widens a transmission band of an optical signal of a predetermined channel to the wavelength filter of an adjacent channel. The management device is further configured to calculate an OSNR of the optical signal based on power loss, calculate a bandwidth of the optical signal according to narrowing due to the wavelength filter, determine whether or not the OSNR and the bandwidth respectively satisfies a condition of transmission quality of the optical signal, and decide whether or not to cause the wavelength selective switch to perform the band setting based on a result of the determination.

A network system includes a plurality of transmission devices, each of which being provided with a wavelength selective switch including a wavelength filter, configured to transmit an optical signal for each channel; and a management device configured to manage the plurality of transmission devices. The wavelength selective switch configured to enable band setting that widens a transmission band of an optical signal of a predetermined channel to the wavelength filter of an adjacent channel. The management device is further configured to calculate an OSNR of the optical signal based on power loss, calculate a bandwidth of the optical signal according to narrowing due to the wavelength filter, determine whether or not the OSNR and the bandwidth respectively satisfies a condition of transmission quality of the optical signal, and decide whether or not to cause the wavelength selective switch to perform the band setting based on a result of the determination.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.