Abstract: A method of controlling a transmission signal, includes transmitting a training signal including four polarization states having a given relation; and performing rotation control and transmission power level control of a polarization component of a data signal, based on a rotation control matrix for a polarization state and an inverse-operation control matrix for a power level imbalance, which are estimated from Stokes parameters related to input power level present on a Poincare sphere acquired from the training signal and Stokes parameters related to output power level present on the Poincare sphere.

Abstract: An optical signal-to-noise ratio measurement device includes a measurement unit and a determination unit and measures an optical signal-to-noise ratio of an optical signal including a fixed pattern in a specified cycle. The measurement unit measures an optical signal-to-noise ratio of the optical signal respectively in a plurality of time sections in a measurement period so as to generate a plurality of measured values, a length of the measurement period being the same or substantially the same as a length of the specified cycle. The determination unit selects, from the plurality of measured values generated by the measurement unit, at least one measured value other than a worst measured value in the plurality of measured values, and determines an optical signal-to-noise ratio of the optical signal based on the selected at least one measured value.

Abstract: A transmission device includes: a receiving unit that receives an optical signal; an acquiring unit that acquires spectrum information from the optical signal, the spectrum information relating to a spectrum of the optical signal; and a narrowing calculating unit that calculates an index value for narrowing of a band of the optical signal by calculating a sampling timing error in accordance with the spectrum information, the sampling timing error being an error when a clock signal is extracted from the optical signal.

Abstract: An optical signal-to-noise ratio (OSNR) measuring device includes a processor, wherein the processor executes a process. The process includes: converting an optical signal to an electrical signal; first acquiring a signal intensity from the electrical signal; second acquiring a noise intensity of a predetermined frequency band from the electrical signal; performing a digital conversion on the noise intensity; and computing an OSNR of the optical signal based on the signal intensity and the converted noise intensity. The predetermined frequency band is a frequency band including a folding noise that occurs when the digital conversion is performed.

Abstract: A network controller includes: a first acquisition unit configured to acquire, based on a signal quality amount of each of wavelength paths set in a network of an optical wavelength-multiplexed transmission system, a signal quality amount of each of spans in each of the wavelength paths; an arithmetic unit configured to calculate a signal quality amount of each of spans in a wavelength path of an estimation target, based on the signal quality amount acquired by the first acquisition unit; and an estimation unit configured to estimate a signal quality amount of the wavelength path of the estimation target, based on the signal quality amount calculated by the arithmetic unit.

Abstract: A transmission device includes: a receiving unit that receives an optical signal; an acquiring unit that acquires spectrum information from the optical signal, the spectrum information relating to a spectrum of the optical signal; and a narrowing calculating unit that calculates an index value for narrowing of a band of the optical signal by calculating a sampling timing error in accordance with the spectrum information, the sampling timing error being an error when a clock signal is extracted from the optical signal.

Abstract: An optical transmission characteristic measurement method includes starting transmission of an optical signal from a transmitting node to a receiving node; receiving a bit error rate value measured by the receiving node and relates to the optical signal; determining whether the bit error rate value is higher than a given threshold; adjusting input power of the optical signal to lower until it is determined that the bit error rate value is higher than the given threshold when it is determined that the bit error rate value is not higher than the given threshold; estimating an optical signal to noise ratio from the bit error rate value when it is determined that the bit error rate value is higher than the given threshold; and calculating an optical signal to noise ratio based on the estimated optical signal to noise ratio and an amount of lowering of the input power.

Abstract: A transmitter generates a frequency-modulated CW light so as to transmit it to a path. A receiver receives the CW light that has passed through passband filters included in the path. The receiver includes a processor. The processor measures an optical power of the received CW light every time a center frequency of the CW light is changed and transmitted by the transmitter. The processor calculates transmission characteristics of the CW light that has passed through the passband filters, on the basis of an average value of the optical power that corresponds to a center frequency of the CW light and on the basis of an amplitude component that indicates an amount of change in the optical power, the average value and the amplitude component being obtained as a result of the measurement.

Abstract: A network control apparatus includes a processor. The processor calculates a first OSNR corresponding to an allowable limit BER from an OSNR yield strength curve of a transmission end in a node of a transmission end. The processor acquires a reception BER of a second node of a reception end, and calculates a second OSNR corresponding to the reception BER from the OSNR yield strength curve of the transmission end. The processor calculates a first noise intensity corresponding to the allowable limit BER from the first OSNR. The processor calculates a second noise intensity corresponding to the reception BER from the second OSNR. The processor calculates a noise intensity margin, based on the first noise intensity and the second noise intensity.

Abstract: A signal quality measurement device includes: a setting processing unit that sets respective passbands of WSSs; and a calculating unit that calculates quality of an optical signal by acquiring a first power of an optical component in a first wavelength band, and a second power of an optical component in a second wavelength band adjacent to the first wavelength band. When the setting processing unit sets each of the passbands of the WWSs, the calculating unit detects a combined power of various ASEs of the optical amplifiers from the second power, and detects the power of the optical signal from the first power and the second power. When the setting processing unit sets the passband of one of the WSSs, the calculating unit detects, from the second power, the ASE of an optical amplifier existing between one of the wavelength selective switches and the receiver.

Abstract: There is provided an apparatus configured to estimate optical transmission performance in a transmission path of an optical signal, the apparatus including a memory, and a processor coupled to the memory and the processor configured to acquire a first index related to a first transmission performance of an optical signal transmitted through a span group between a first node and an n-th node and a second index related to a second transmission performance of an optical signal transmitted through a span or a span group between the first node and an m-th node, wherein n is an integer of 3 or more, and m is the integer satisfying m<n, and estimate a third index related to a third transmission performance of an optical signal to be transmitted through a span between the m-th node and the n-th node, based on the first index and the second index.

Abstract: An optical signal-to-noise ratio measurement device includes a measurement unit and a determination unit and measures an optical signal-to-noise ratio of an optical signal including a fixed pattern in a specified cycle. The measurement unit measures an optical signal-to-noise ratio of the optical signal respectively in a plurality of time sections in a measurement period so as to generate a plurality of measured values, a length of the measurement period being the same or substantially the same as a length of the specified cycle. The determination unit selects, from the plurality of measured values generated by the measurement unit, at least one measured value other than a worst measured value in the plurality of measured values, and determines an optical signal-to-noise ratio of the optical signal based on the selected at least one measured value.

Abstract: A signal quality measurement device includes: a setting processing unit that sets respective passbands of WSSs; and a calculating unit that calculates quality of an optical signal by acquiring a first power of an optical component in a first wavelength band, and a second power of an optical component in a second wavelength band adjacent to the first wavelength band. When the setting processing unit sets each of the passbands of the WWSs, the calculating unit detects a combined power of various ASEs of the optical amplifiers from the second power, and detects the power of the optical signal from the first power and the second power. When the setting processing unit sets the passband of one of the WSSs, the calculating unit detects, from the second power, the ASE of an optical amplifier existing between one of the wavelength selective switches and the receiver.

Abstract: A method of controlling a transmission signal, includes transmitting a training signal including four polarization states having a given relation; and performing rotation control and transmission power level control of a polarization component of a data signal, based on a rotation control matrix for a polarization state and an inverse-operation control matrix for a power level imbalance, which are estimated from Stokes parameters related to input power level present on a Poincare sphere acquired from the training signal and Stokes parameters related to output power level present on the Poincare sphere.

Abstract: An optical signal-to-noise ratio monitor includes: a measuring unit that measures an optical signal-to-noise ratio of a polarization multiplexed optical signal, a polarization state of the polarization multiplexed optical signal changing with respect to time; a selector that selects, from a plurality of optical signal-to-noise ratios measured by the measuring unit at a plurality of measurement points within a designated measurement period, an optical signal-to-noise ratio that is higher than an average of the plurality of optical signal-to-noise ratios; and an output unit that outputs the optical signal-to-noise ratio selected by the selector.

Abstract: An optical transmission characteristic measurement method includes starting transmission of an optical signal from a transmitting node to a receiving node; receiving a bit error rate value measured by the receiving node and relates to the optical signal; determining whether the bit error rate value is higher than a given threshold; adjusting input power of the optical signal to lower until it is determined that the bit error rate value is higher than the given threshold when it is determined that the bit error rate value is not higher than the given threshold; estimating an optical signal to noise ratio from the bit error rate value when it is determined that the bit error rate value is higher than the given threshold; and calculating an optical signal to noise ratio based on the estimated optical signal to noise ratio and an amount of lowering of the input power.

Abstract: A network controller includes: a first acquisition unit configured to acquire, based on a signal quality amount of each of wavelength paths set in a network of an optical wavelength-multiplexed transmission system, a signal quality amount of each of spans in each of the wavelength paths; an arithmetic unit configured to calculate a signal quality amount of each of spans in a wavelength path of an estimation target, based on the signal quality amount acquired by the first acquisition unit; and an estimation unit configured to estimate a signal quality amount of the wavelength path of the estimation target, based on the signal quality amount calculated by the arithmetic unit.

Abstract: An optical transmission apparatus includes a variable attenuator configured to adjust output intensity of each wavelength signal included in a multiplexed optical signal having been input; a monitor configured to measure an output spectrum of the variable attenuator; a calculation unit configured to calculate an amount of spectral narrowing and an amount of spectral surplus, based on a measured value by the monitor, and a target value set in advance; and a control unit configured to control an amount of attenuation of the variable attenuator, based on the amount of spectral narrowing and the amount of spectral surplus.

Abstract: An optical signal quality monitoring apparatus includes: a holding unit configured to hold a relational expression representing a relationship among an optical signal intensity, a noise intensity, and an optical signal-to-noise ratio and a plurality of calibration coefficients used in the relational expression; a measurement unit configured to measure an optical power of input light and a noise power in the input light; an arithmetic unit configured to calculate a plurality of optical signal-to-noise ratios, based on the optical power and the noise power measured by the measurement unit, by using the relational expression and the plurality of calibration coefficients; and a determination unit configured to select one optical signal-to-noise ratio from the plurality of optical signal-to-noise ratios, based on a magnitude relationship of the plurality of optical signal-to-noise ratios calculated by the arithmetic unit.

Abstract: A network controller includes: a first acquisition unit configured to acquire, based on a signal quality amount of each of wavelength paths set in a network of an optical wavelength-multiplexed transmission system, a signal quality amount of each of spans in each of the wavelength paths; an arithmetic unit configured to calculate a signal quality amount of each of spans in a wavelength path of an estimation target, based on the signal quality amount acquired by the first acquisition unit; and an estimation unit configured to estimate a signal quality amount of the wavelength path of the estimation target, based on the signal quality amount calculated by the arithmetic unit.