Abstract: A decoding method includes: receiving a plurality of subcarrier signals each including encoded data; acquiring a predetermined amount of data from each of the plurality of subcarrier signals; correcting errors in the plurality of subcarrier signals by performing decoding arithmetic processing on the respective predetermined amounts of data acquired from the plurality of subcarrier signals in a time-division manner; and causing the decoding arithmetic processing to be consecutively performed on each of the predetermined amounts of data a predetermined number of times.

Abstract: An encoding circuit includes an allocator configured to allocate symbols among a plurality of symbols within a constellation of multilevel modulation and correspond to values of a plurality of bit stings, a converter configured to convert values of each of bit strings excluding a first bit string so that, as a region within the constellation is closer to the center of the constellation, the number of symbols allocated in the region is larger, a switch configured to switch between a first time period in which a first error correction code is inserted and a second time period in which the first error correction code is not inserted, and an insertor configured to generate the first error correction code from a second bit string in the second time period and inserts the first error correction code in two or more bit strings in the first time period according to the switching.

Abstract: A decoding method includes: receiving a plurality of subcarrier signals each including encoded data; acquiring a predetermined amount of data from each of the plurality of subcarrier signals; correcting errors in the plurality of subcarrier signals by performing decoding arithmetic processing on the respective predetermined amounts of data acquired from the plurality of subcarrier signals in a time-division manner; and causing the decoding arithmetic processing to be consecutively performed on each of the predetermined amounts of data a predetermined number of times.

Abstract: An encoding circuit includes an allocator configured to allocate symbols among a plurality of symbols within a constellation of multilevel modulation and correspond to values of a plurality of bit stings, a converter configured to convert values of each of bit strings excluding a first bit string so that, as a region within the constellation is closer to the center of the constellation, the number of symbols allocated in the region is larger, a switch configured to switch between a first time period in which a first error correction code is inserted and a second time period in which the first error correction code is not inserted, and an insertor configured to generate the first error correction code from a second bit string in the second time period and inserts the first error correction code in two or more bit strings in the first time period according to the switching.

Abstract: An encoding circuit includes an allocator configured to allocate symbols among a plurality of symbols within a constellation of multilevel modulation and correspond to values of a plurality of bit strings, a converter configured to convert values of each of bit strings excluding a first bit string so that, as a region within the constellation is closer to the center of the constellation, the number of symbols allocated in the region is larger, a switch configured to switch between a first time period in which a first error correction code is inserted and a second time period in which the first error correction code is not inserted, and an insertor configured to generate the first error correction code from a second bit string in the second time period and inserts the first error correction code in two or more bit strings in the first time period according to the switching.

Abstract: An optical communication system includes a first communication device configured to transmit optical signals, and a second communication device configured to receive the optical signals. The first transmission device includes encoding circuit that configured to assign, to a plurality of bit strings, symbols each corresponding to a value of every one of the plurality of bit strings, the symbols being among a plurality of symbols in a constellation of a multi-level modulation scheme, convert values of bit strings, generate the second error correction code from a second bit string among the plurality of bit strings in every one of a plurality of periods, delay the first error correction code, and delay the second error correction code, wherein the encoding circuit uses the delayed first error correction code and the delayed second error correction code to convert a value of the second bit string.

Abstract: An encoding circuit includes an allocator configured to allocate symbols among a plurality of symbols within a constellation of multilevel modulation and correspond to values of a plurality of bit strings, a converter configured to convert values of each of bit strings excluding a first bit string so that, as a region within the constellation is closer to the center of the constellation, the number of symbols allocated in the region is larger, a switch configured to switch between a first time period in which a first error correction code is inserted and a second time period in which the first error correction code is not inserted, and an insertor configured to generate the first error correction code from a second bit string in the second time period and inserts the first error correction code in two or more bit strings in the first time period according to the switching.

Abstract: An optical communication system includes a first communication device configured to transmit optical signals, and a second communication device configured to receive the optical signals. The first transmission device includes encoding circuit that configured to assign, to a plurality of bit strings, symbols each corresponding to a value of every one of the plurality of bit strings, the symbols being among a plurality of symbols in a constellation of a multi-level modulation scheme, convert values of bit strings, generate the second error correction code from a second bit string among the plurality of bit strings in every one of a plurality of periods, delay the first error correction code, and delay the second error correction code, wherein the encoding circuit uses the delayed first error correction code and the delayed second error correction code to convert a value of the second bit string.

Abstract: An optical communication apparatus includes a first monitor that monitors a first signal carried on a first polarization and outputs a first monitor value representing a transmission characteristic of the first signal, a second monitor that monitors a second signal carried on a second polarization orthogonal to the first polarization and outputs a second monitor value representing a transmission characteristic of the second signal, and a transmitting circuit that notifies a transmitting source of the first signal and the second signal of the first monitor value and the second monitor value.

Abstract: A transmission device to multiplex in a first signal a plurality of second signals each having a low rate as compared with the first signal, the transmission device includes: a plurality of memories to store the plurality of second signals; a selector to select one of the second signals read from the plurality of memories; and a controller to control read timing to read the plurality of second signals from the plurality of memories and signal selection timing to select the one of the second signals by the selector so as to execute rearrangement processing of the plurality of second signals read from the plurality of memories in accordance with cross-connect setting information for the plurality of second signals and shift processing of the plurality of second signals read from the plurality of memories in accordance with multiplexing positions of the plurality of second signals for the first signal.

Abstract: A transmission device to multiplex in a first signal a plurality of second signals each having a low rate as compared with the first signal, the transmission device includes: a plurality of memories to store the plurality of second signals; a selector to select one of the second signals read from the plurality of memories; and a controller to control read timing to read the plurality of second signals from the plurality of memories and signal selection timing to select the one of the second signals by the selector so as to execute rearrangement processing of the plurality of second signals read from the plurality of memories in accordance with cross-connect setting information for the plurality of second signals and shift processing of the plurality of second signals read from the plurality of memories in accordance with multiplexing positions of the plurality of second signals for the first signal.