Abstract: A communication system includes a transmitting device that transmits a signal based on pluralities of symbol coordinates on a constellation and pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates, average coordinates of the pluralities of trajectory coordinates being different coordinates from coordinates of origin, and a receiving device that accumulates pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates on the constellation in the signal received from the transmitting device, and estimates a phase of the signal received from the transmitting device based on a value representing a difference between average coordinates of the pluralities of trajectory coordinates accumulated and the different coordinates.

Abstract: An optical transmission system includes: a first optical transmission apparatus configured to add an error correction code (ECC) having a code length in accordance with transmission quality of each of sub-carriers forming a super channel to a main signal, retrieve, from the ECC added to the main signal on a sub-carrier to be processed, a code portion in excess of a predetermined redundancy level, distribute the code portion to another sub-carrier, and concatenate the code portion of the ECC to be added to a main signal on the another sub-carrier into the ECC added to a main signal on the sub-carrier to be processed; and a second optical transmission apparatus configured to concatenate the cord portion of the ECC distributed from another sub-carrier into the ECC included in the optical signal, and decode a main signal in the optical signal on a corresponding sub-carrier by using the concatenated ECC.

Abstract: A communication system includes a transmission device that transmits a signal, based on a plurality of symbol coordinates on a constellation, which characterize a shape having a predetermined rotational asymmetrical shape, and a receiving device that accumulates symbol coordinates on the constellation in the signal received from the transmission device and estimates the phase of the signal received from the transmission device, based on a difference between the direction of a shape characterized by the accumulated symbol coordinates and the direction of the predetermined shape.

Abstract: A communication system includes a transmission device that transmits a signal, based on a plurality of symbol coordinates on a constellation, which characterize a shape having a predetermined rotational asymmetrical shape, and a receiving device that accumulates symbol coordinates on the constellation in the signal received from the transmission device and estimates the phase of the signal received from the transmission device, based on a difference between the direction of a shape characterized by the accumulated symbol coordinates and the direction of the predetermined shape.

Abstract: A communication system includes a transmitting device that transmits a signal based on pluralities of symbol coordinates on a constellation and pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates, average coordinates of the pluralities of trajectory coordinates being different coordinates from coordinates of origin, and a receiving device that accumulates pluralities of trajectory coordinates between respective ones of the pluralities of symbol coordinates on the constellation in the signal received from the transmitting device, and estimates a phase of the signal received from the transmitting device based on a value representing a difference between average coordinates of the pluralities of trajectory coordinates accumulated and the different coordinates.

Abstract: A plurality of error correction circuits connected in series include a calculator circuit that corrects the codeword when the determination results of a determination circuit indicate that the error correction circuit at the present stage is to correct the codeword, and a determination circuit at a subsequent error correction apparatus determines whether the error correction circuit at the subsequent stage is to correct the codeword when the determination results of the determination circuit indicate that the error correction circuit at the present stage is not to correct the codeword.

Abstract: An optical transmission apparatus including a variable optical attenuator is provided. The optical transmission apparatus includes a module detection portion for detecting a type of module that receives light attenuated by the variable optical attenuator; and a variable optical attenuator control portion for controlling so as to change control parameters of the variable optical attenuator in accordance with the type of module detected by the module detection portion.

Abstract: An optical transmission system transmits an optical signal of multi-level modulation. In a transmitter module, a data string in a specified frame is rearranged into a plurality of logical lanes. A lane ID, which specifies in what logical lane out of the plurality of logical lanes a start of the data string is arranged, is assigned to a non-scrambled area in an overhead portion of the frame. The lane ID corresponding to one of the plurality of logical lanes is different from the lane IDs corresponding to the other remaining logical lanes. The optical signal is generated using the data string rearranged into the plurality of logical lanes. In a receiver, the lane ID is detected according to a majority method. The inversion of bits and the swapping of lanes are detected using the lane ID and compensated.

Abstract: A plurality error correction circuits connected with series includes a calculator circuit corrects the codeword when the determination results of a determining circuit indicate that the error correcting circuit at the present stage is to correct the codeword, and a determining circuit at a subsequent error correction apparatus determines whether the error correcting circuit at the subsequent stage is to correct the codeword when the determination results of the determining circuit indicate that the error correcting circuit at the present stage is not to correct the codeword.

Abstract: An optical transmission system transmits an optical signal of multi-level modulation. In a transmitter module, a data string in a specified frame is rearranged into a plurality of logical lanes. A lane ID, which specifies in what logical lane out of the plurality of logical lanes a start of the data string is arranged, is assigned to a non-scrambled area in an overhead portion of the frame. The lane ID corresponding to one of the plurality of logical lanes is different from the lane IDs corresponding to the other remaining logical lanes. The optical signal is generated using the data string rearranged into the plurality of logical lanes. In a receiver, the lane ID is detected according to a majority method. The inversion of bits and the swapping of lanes are detected using the lane ID and compensated.

Abstract: A clock recovery apparatus allows that a clock of data is transparent before and after a relay. A clock recovery apparatus for performing clock recovery from a received signal, the clock recovery apparatus receiving a signal transmitted from a transmission apparatus converting a signal having a first signal-format with a first clock frequency into a signal having a second signal-format and transmitting the signal to the clock recovery apparatus in accordance with a second clock frequency, the clock recovery apparatus includes a signal processing section for converting the received signal into a signal having the first signal-format, and a clock recovery section for recovering the first clock frequency on a basis of a cycle produced by counting data of the signal obtained by the signal having the first signal-format processing section in a certain number.

Abstract: An optical transmission apparatus including a variable optical attenuator is provided. The optical transmission apparatus includes a module detection portion for detecting a type of module that receives light attenuated by the variable optical attenuator; and a variable optical attenuator control portion for controlling so as to change control parameters of the variable optical attenuator in accordance with the type of module detected by the module detection portion.

Abstract: An optical amplifier is provided with a controlling unit for controlling a gain of the optical amplifier based on input light power and output light power of the optical amplifier, as well as a gain control amount variable unit for changing the gain control amount of the optical amplifier by the controlling unit according to at least one of the input light power and the output light power. Thereby, optical communication, which can follow the change in the input power of the optical amplifier in high speed and also is stable, can be realized, without causing the occurrence of an oscillation phenomenon, the large size of the optical amplifier, and the increase in power consumption and heating.

Abstract: An optical amplifier is provided with a controlling unit for controlling a gain of the optical amplifier based on input light power and output light power of the optical amplifier, as well as a gain control amount variable unit for changing the gain control amount of the optical amplifier by the controlling unit according to at least one of the input light power and the output light power. Thereby, optical communication, which can follow the change in the input power of the optical amplifier in high speed and also is stable, can be realized, without causing the occurrence of an oscillation phenomenon, the large size of the optical amplifier, and the increase in power consumption and heating.

Abstract: An optical amplifier is provided with a controlling unit for controlling a gain of the optical amplifier based on input light power and output light power of the optical amplifier, as well as a gain control amount variable unit for changing the gain control amount of the optical amplifier by the controlling unit according to at least one of the input light power and the output light power. Thereby, optical communication, which can follow the change in the input power of the optical amplifier in high speed and also is stable, can be realized, without causing the occurrence of an oscillation phenomenon, the large size of the optical amplifier, and the increase in power consumption and heating.

Abstract: An optical amplifier is provided with a controlling unit for controlling a gain of the optical amplifier based on input light power and output light power of the optical amplifier, as well as a gain control amount variable unit for changing the gain control amount of the optical amplifier by the controlling unit according to at least one of the input light power and the output light power. Thereby, optical communication, which can follow the change in the input power of the optical amplifier in high speed and also is stable, can be realized, without causing the occurrence of an oscillation phenomenon, the large size of the optical amplifier, and the increase in power consumption and heating.