Abstract: An optical transmission system, in which an optical transmission apparatus and an optical reception apparatus are provided, includes a coefficient determination unit configured to optimize, based on a reception signal received by the optical reception apparatus, a coefficient to be used to compensate for deterioration according to characteristics of each device configuring a transmission path between the optical transmission apparatus and the optical reception apparatus, and a device characteristic estimation unit configured to estimate the characteristics of each device by using the optimized coefficient.

Abstract: An aspect of the present invention is an adaptive equalization filter for an optical transmission system, including: a main signal filter; and a coefficient computation unit that updates the filter coefficient of the main signal filter. The pre-stage filter and the post-stage filter receive a sample of the main signal as an input. The pre-stage coefficient computation unit obtains the filter coefficient of the pre-stage filter by feedback control using the gradient method. The post-stage coefficient computation unit obtains the filter coefficient of the post-stage filter by feedforward control. The convolution computation unit obtains the filter coefficient of the main signal filter by convolution computation of the filter coefficient of the pre-stage filter obtained by the pre-stage coefficient computation unit and the filter coefficient of the post-stage filter obtained by the post-stage coefficient computation unit.

Abstract: A communication device includes an amplitude conversion unit configured to generate a symbol sequence according to a bit sequence, a distribution matching unit configured to add redundant bits to the symbol sequence through probabilistic amplitude shaping (PAS) coding, an insertion unit configured to insert a pilot symbol into the symbol sequence to which the redundant bits have been added and transmit the symbol sequence into which the pilot symbol has been inserted to a transmission path, and a control unit configured to acquire information on the transmission path and change, according to the information on the transmission path, allocation of the redundancy of the PAS coding and the redundancy of the pilot symbol in a range of redundancy that is able to be allocated depending on a predetermined throughput.

Abstract: An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.

Abstract: An optical reception device includes a nonlinear optical compensation section which performs compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and compensation of a nonlinear optical effect of the received signal N (N is an integer of at least 1) step(s), and a coefficient update section which updates a coefficient so as to optimize the coefficient used in each step of the nonlinear optical compensation section based on a signal having been subjected to the compensation by the nonlinear optical compensation section and a predetermined training signal.

Abstract: An optical transmission system, in which an optical transmission apparatus and an optical reception apparatus are provided, includes a coefficient determination unit configured to optimize, based on a reception signal received by the optical reception apparatus, a coefficient to be used to compensate for deterioration according to characteristics of each device configuring a transmission path between the optical transmission apparatus and the optical reception apparatus, and a device characteristic estimation unit configured to estimate the characteristics of each device by using the optimized coefficient.

Abstract: An optical reception apparatus includes a wavelength dispersion compensation unit that performs wavelength dispersion compensation individually on reception signals that are obtained by receiving, by a coherent detecting scheme, an optical signal modulated in a subcarrier modulation scheme and by performing division on a subcarrier-by-subcarrier basis, and a plurality of delay compensation units that compensate for a delay between reception signals at different subcarriers among the reception signals at subcarriers obtained by the wavelength dispersion compensation.

Abstract: An optical reception device includes a coefficient update section which optimizes a dispersion coefficient used in compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and a phase rotation amount used in compensation of a nonlinear optical effect of the received signal, and a transmission characteristic estimation section which estimates a transmission characteristic of a transmission line by using the optimized dispersion coefficient and the optimized phase rotation amount.

Abstract: A communication device includes an amplitude conversion unit configured to generate a symbol sequence according to a bit sequence, a distribution matching unit configured to add redundant bits to the symbol sequence through probabilistic amplitude shaping (PAS) coding, an insertion unit configured to insert a pilot symbol into the symbol sequence to which the redundant bits have been added and transmit the symbol sequence into which the pilot symbol has been inserted to a transmission path, and a control unit configured to acquire information on the transmission path and change, according to the information on the transmission path, allocation of the redundancy of the PAS coding and the redundancy of the pilot symbol in a range of redundancy that is able to be allocated depending on a predetermined throughput.

Abstract: An optical reception device includes a nonlinear optical compensation section which performs compensation of wavelength dispersion of a received signal obtained by receiving an optical signal according to a coherent detection method and compensation of a nonlinear optical effect of the received signal N (N is an integer of at least 1) step(s), and a coefficient update section which updates a coefficient so as to optimize the coefficient used in each step of the nonlinear optical compensation section based on a signal having been subjected to the compensation by the nonlinear optical compensation section and a predetermined training signal.