Abstract: A multilevel modulation optical transceiver for distributing an OTN frame defined by ITU-T to a plurality of lanes for transmission, the multilevel modulation optical transceiver including: an MLD transmission unit; and a data replication unit, further including a data rearrangement unit arranged at a preceding stage of the MLD transmission unit, for performing data rearrangement processing of replicating, in advance, a frame synchronization pattern of an overhead of the OTN frame before being subjected to the lane rotation processing from a first lane that has the overhead to another lane that does not have the overhead, and of saving a payload to be overwritten with the frame synchronization pattern to a reserved area of the overhead to enable the payload to be restored on a reception side.

Abstract: An optical transmission apparatus includes: an optical transmitter; and an optical receiver. The optical transmitter has a plurality of modulation rules, switches the plurality of modulation rules to generate optical signals, multiplexes the optical signals with orthogonal polarizations, randomizes phases of the optical signals, and transmits the optical signals. The optical receiver includes: a coherent detector for causing interference between received optical signals and local oscillation light to convert the optical signals into electrical signals; a polarization splitter and adaptive equalizer for subjecting the electrical signals to polarization splitting and adaptive equalization; and decoders for performing decoding or differential detection on the electrical signals on which polarization splitting and adaptive equalization have been performed.

Abstract: An input bit error ratio estimating method executed by a communication control unit includes a computing, a condition determining, a first input BER estimating, a second input BER estimating, a third input BER estimating, and an input BER estimation result outputting. In the condition determining, the communication control unit determines which of a plurality of conditions set in advance to be narrowed down to one has been established, based on a post-internal decoding residual error detection ratio. Based on the condition that is determined in the condition determining as one that has been established, the communication control unit selects one out of a plurality of processing procedures for estimating the input BER, namely, selects one of the first input BER estimating to the third input BER estimating and executes the selected processing.

Abstract: A differential code optical transmission and reception device including: a digital signal processing optical transceiver that converts information data into an optical signal and transmits it to a communication channel, a reception front end part that receives the optical signal from the communication channel, an O/E conversion part that converts the optical signal received from the communication channel into an electrical signal, a skew correction part that regulates or correct a skew between lanes contained in the electrical signal, a differential decoder that decodes a differential code of the skew corrected electrical signal, and a lane exchange/rotation part that rearranges the electrical signal having passed through the differential decoder into a lane state thereof at the time of transmission in cases where lane exchange has occurred in the communication channel.

Abstract: An input bit error ratio estimating method executed by a communication control unit includes a computing, a condition determining, a first input BER estimating, a second input BER estimating, a third input BER estimating, and an input BER estimation result outputting. In the condition determining, the communication control unit determines which of a plurality of conditions set in advance to be narrowed down to one has been established, based on a post-internal decoding residual error detection ratio. Based on the condition that is determined in the condition determining as one that has been established, the communication control unit selects one out of a plurality of processing procedures for estimating the input BER, namely, selects one of the first input BER estimating to the third input BER estimating and executes the selected processing.

Abstract: A repeater includes a variable optical attenuating unit that collectively attenuates WDM optical signal input, an optical-attenuation adjusting unit that adjusts attenuation in the variable optical attenuating unit, and an optical amplifying unit that collectively amplifies and outputs the WDM optical signal collectively attenuated, to a downstream side. An optical-attenuation adjusting unit includes an input level detector; an output level detector; an output-level transmitting unit that receives information of a signal level of WDM optical signal output by a repeater at an upstream side and transmits information of a signal level of the WDM optical signal detected by the output level detector to a repeater at a downstream side; and an attenuation amount controller that controls the variable optical attenuating unit by calculating an attenuation amount thereof based on information of a signal level detected by the input level detector and a signal level received by the output-level transmitting unit.

Abstract: A digital signal processing optical transceiver includes: a reception front end for separating an optical reception signal from a communication path into a total of four channels including an I-channel and a Q-channel of an X-polarized wave component and an I-channel and a Q-channel of a Y-polarized wave component; and a digital signal processing unit for: performing signal point determination with respect to signals of the four channels; when there are only two signal points, selecting two channels including an I-channel component of an X-polarized wave and an I-channel component of a Y-polarized wave and performing signal processing thereon; and when there are four signal points, selecting the four channels including the I-channel component and a Q-channel component of the X-polarized wave and the I-channel component and a Q-channel component of the Y-polarized wave and performing the signal processing thereon.

Abstract: A differential code optical transmission and reception device including: a digital signal processing optical transceiver that converts information data into an optical signal and transmits it to a communication channel, a reception front end part that receives the optical signal from the communication channel, an O/E conversion part that converts the optical signal received from the communication channel into an electrical signal, a skew correction part that regulates or correct a skew between lanes contained in the electrical signal, a differential decoder that decodes a differential code of the skew corrected electrical signal, and a lane exchange/rotation part that rearranges the electrical signal having passed through the differential decoder into a lane state thereof at the time of transmission in cases where lane exchange has occurred in the communication channel.

Abstract: A repeater includes a variable optical attenuating unit that collectively attenuates WDM optical signal input, an optical-attenuation adjusting unit that adjusts attenuation in the variable optical attenuating unit, and an optical amplifying unit that collectively amplifies and outputs the WDM optical signal collectively attenuated, to a downstream side. An optical-attenuation adjusting unit includes an input level detector; an output level detector; an output-level transmitting unit that receives information of a signal level of WDM optical signal output by a repeater at an upstream side and transmits information of a signal level of the WDM optical signal detected by the output level detector to a repeater at a downstream side; and an attenuation amount controller that controls the variable optical attenuating unit by calculating an attenuation amount thereof based on information of a signal level detected by the input level detector and a signal level received by the output-level transmitting unit.