Abstract: An optical transceiver includes processing circuitry to calculate, when test signals are sent to a transmission line from a transmitter and a receiver receives the test signals having passed through a wavelength filter, a bandwidth of the received test signals, the transmitter generating, as the test signals, a collection of narrowband signals, the narrowband signals having a narrower bandwidth than a bandwidth of the wavelength filter and having different frequencies, and the wavelength filter included in an optical splitter inserted in the transmission line, and the collection of narrowband signals including a narrowband signal having a higher frequency than a highest frequency in the bandwidth of the wavelength filter and a narrowband signal having a lower frequency than a lowest frequency in the bandwidth of the wavelength filter, and to determine a modulation rate and a modulation level of the transmission signal depending on the calculated bandwidth.

Abstract: An optical transceiver includes processing circuitry to calculate, when test signals are sent to a transmission line from a transmitter and a receiver receives the test signals having passed through a wavelength filter, a bandwidth of the received test signals, the transmitter generating, as the test signals, a collection of narrowband signals, the narrowband signals having a narrower bandwidth than a bandwidth of the wavelength filter and having different frequencies, and the wavelength filter included in an optical splitter inserted in the transmission line, and the collection of narrowband signals including a narrowband signal having a higher frequency than a highest frequency in the bandwidth of the wavelength filter and a narrowband signal having a lower frequency than a lowest frequency in the bandwidth of the wavelength filter, and to determine a modulation rate and a modulation level of the transmission signal depending on the calculated bandwidth.

Abstract: A coherent receiver performing coherent detection on polarization multiplex light into which first polarization light and second polarization light are multiplexed, and splitting the polarization multiplex light into the first polarization light and the second polarization light, an adaptive equalizer compensating the waveform distortion of a signal superimposed onto the first polarization light by using a first FIR filter, compensating the waveform distortion of a signal superimposed onto the second polarization light by using a second FIR filter, and by decoding each of the signals whose waveform distortion has been compensated, generating their respective decoded data, an error ratio calculator calculating the bit error ratio of each decoded data generated by the adaptive equalizer, a margin calculator calculating a margin from the bit error ratio of an error correction limit in each bit error ratio calculated by the error ratio calculator, and a tap number controller setting up the numbers of taps of the

Abstract: A signal shaping device includes: a generation unit to perform plural types of predetermined processes on blocks obtained by dividing plural sequences of bit strings by a predetermined length, and generate a plurality of candidate blocks that are candidates for a shaped block to be transmitted; a calculation unit to calculate, on a candidate-block-by-candidate-block basis, a weight of a one-dimensional modulation symbol when a plurality of bits included in the candidate block are converted into the one-dimensional modulation symbol; a selection unit to select, from among the candidate blocks, the shaped block on a basis of the weight; an addition unit to add, to the shaped block, selection information indicating a selection result; and a symbol mapping unit to generate a one-dimensional modulation signal by converting a plurality of bits included in the shaped block, into the one-dimensional modulation symbol.

Abstract: A signal shaping device includes: a generation unit to perform plural types of predetermined processes on blocks obtained by dividing plural sequences of bit strings by a predetermined length, and generate a plurality of candidate blocks that are candidates for a shaped block to be transmitted; a calculation unit to calculate, on a candidate-block-by-candidate-block basis, a weight of a one-dimensional modulation symbol when a plurality of bits included in the candidate block are converted into the one-dimensional modulation symbol; a selection unit to select, from among the candidate blocks, the shaped block on a basis of the weight; an addition unit to add, to the shaped block, selection information indicating a selection result; and a symbol mapping unit to generate a one-dimensional modulation signal by converting a plurality of bits included in the shaped block, into the one-dimensional modulation symbol.

Abstract: A coherent receiver performing coherent detection on polarization multiplex light into which first polarization light and second polarization light are multiplexed, and splitting the polarization multiplex light into the first polarization light and the second polarization light, an adaptive equalizer compensating the waveform distortion of a signal superimposed onto the first polarization light by using a first FIR filter, compensating the waveform distortion of a signal superimposed onto the second polarization light by using a second FIR filter, and by decoding each of the signals whose waveform distortion has been compensated, generating their respective decoded data, an error ratio calculator calculating the bit error ratio of each decoded data generated by the adaptive equalizer, a margin calculator calculating a margin from the bit error ratio of an error correction limit in each bit error ratio calculated by the error ratio calculator, and a tap number controller setting up the numbers of taps of the

Abstract: Each of a first filter to a fourth filter is an FIR filter having one tap. Each of a fifth filter and a sixth filter is an FIR filter having less than 46 taps. As a result, it is possible to obtain an adaptive equalization filter having a smaller total number of taps than an adaptive equalization filter using an FIR filter having 24 taps as each of the first to fourth filters.

Abstract: Each of a first filter to a fourth filter is an FIR filter having one tap. Each of a fifth filter and a sixth filter is an FIR filter having less than 46 taps. As a result, it is possible to obtain an adaptive equalization filter having a smaller total number of taps than an adaptive equalization filter using an FIR filter having 24 taps as each of the first to fourth filters.

Abstract: An optical communication apparatus receives a signal in which optical signals each including multiplexed subcarriers are frequency multiplexed, and includes: transceivers to perform reception process on a processing target band in which any one of the optical signals is included and to calculate a frequency offset amount between local light and a reception target optical signal that is included in the processing target band and calculate a carrier frequency interval between the local light and an optical signal adjacent to the reception target optical signal; and a frequency control unit to calculate an adjustment amount when an optical communication apparatus that is a source of the optical signals adjusts the frequencies of the optical signals based on the frequency offset amount and the carrier frequency interval calculated by the transceivers and to transmit the calculated adjustment amount to the optical communication apparatus that is a source of the optical signals.

Abstract: An optical communication apparatus receives a signal in which optical signals each including multiplexed subcarriers are frequency multiplexed, and includes: transceivers to perform reception process on a processing target band in which any one of the optical signals is included and to calculate a frequency offset amount between local light and a reception target optical signal that is included in the processing target band and calculate a carrier frequency interval between the local light and an optical signal adjacent to the reception target optical signal; and a frequency control unit to calculate an adjustment amount when an optical communication apparatus that is a source of the optical signals adjusts the frequencies of the optical signals based on the frequency offset amount and the carrier frequency interval calculated by the transceivers and to transmit the calculated adjustment amount to the optical communication apparatus that is a source of the optical signals.

Abstract: An optical transmission method wavelength-multiplexing and transmitting multiple channels including data. The data are composed of data areas independent between the channels and data areas non-independent between the channels. Data patterns of the data areas non-independent between the channels are variable. The data patterns of the data areas non-independent between the channels are set so that in time periods of the non-independent data areas on an optical transmission section, a time period during which polarization states of the multiple channels are correlated in the optical transmission section has a length such that an error rate is less than or equal to a threshold value, the error rate being determined from a temporal distribution of bit errors obtained from a result of error decision after demodulation in an optical receiver.

Abstract: A communication apparatus including: an optical transmission device including transceivers to transmit and receive optical signals at carrier wave frequencies different from one another; a multiplexing unit to subject the optical signals input from the transceivers to frequency multiplexing; an auxiliary transceiver to perform mixing interference of a frequency multiplexing signal and a local emission light signal having the same frequency setting as a carrier wave frequency used in a control target transceiver, to generate and output a control signal for correcting the carrier wave frequency of the control target transceiver, the auxiliary transceiver being a spare transceiver for the plurality of transceivers; and a control unit to perform control to output, to the control target transceiver, the control signal input from the auxiliary transceiver.

Abstract: An optical transmission device includes a data duplicating unit that duplicates signals of each of the lanes subjected to symbol mapping and sets the number of the lanes to the number of lanes of a first number; a waveform converting unit that waveform-converts a signal that can take a value of a type of a second number into a signal that can take a value of a type of a third number larger than the second number; a polarity inverting unit that inverts polarity; a lane replacing unit that performs replacement of lanes in two or more lanes; and an optical-signal generating unit that converts electric signals of the signals of each of the lanes input from the lane replacing unit into optical signals and combines and outputs the optical signals of the lanes.

Abstract: A communication apparatus including: an optical transmission device including transceivers to transmit and receive optical signals at carrier wave frequencies different from one another; a multiplexing unit to subject the optical signals input from the transceivers to frequency multiplexing; an auxiliary transceiver to perform mixing interference of a frequency multiplexing signal and a local emission light signal having the same frequency setting as a carrier wave frequency used in a control target transceiver, to generate and output a control signal for correcting the carrier wave frequency of the control target transceiver, the auxiliary transceiver being a spare transceiver for the plurality of transceivers; and a control unit to perform control to output, to the control target transceiver, the control signal input from the auxiliary transceiver.

Abstract: An optical transmission method wavelength-multiplexes and transmits multiple channels. Data transmitted on the wavelength-multiplexed channels are composed of data areas independent between the channels and data areas non-independent between the channels. Data patterns of the data areas non-independent between the channels are variable. This reduces the time period during which polarization states of the multiple channels are correlated, thereby reducing non-linear optical effects occurring between the channels and reducing deterioration in signal quality at a receiving end.