US 12,671,498 B2Granted

Optical receiving apparatus and optical receiving method using changing coefficient values for fast fourier transform

AssigneeNTT, Inc.

InventorsKengo Horikoshi, Masanori Nakamura, Seiji Okamoto, Etsushi Yamazaki, Asuka Matsushita, Takeo Sasai

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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.

Claims4

Dependent claims

An optical reception apparatus comprising:

at least one wavelength dispersion compensation unit configured to perform wavelength dispersion compensation for each subcarrier contained in a reception signal obtained by interfering a received optical signal and a local light emission;
and
a plurality of delay compensation units configured to compensate for a delay between reception signals at different subcarriers among the reception signals at subcarriers obtained by the wavelength dispersion compensation, wherein
the at least one wavelength dispersion compensation unit comprises a plurality of wavelength dispersion compensation units, and
each of the plurality of wavelength dispersion compensation units delimits a reception signal of the reception signals input into blocks each having a specific length such that an overlapping portion having a predetermined length between adjacent blocks is generated, outputs the blocks delimited, performs a Fourier transform for each of the blocks, holds the blocks that are temporally consecutive after the Fourier transform, applies a coefficients defined according to a wavelength dispersion compensation amount in accordance with a frequency position and a delay amount in accordance with the frequency position and a time position to each of the blocks held, generates a coefficients applied block by adding up a coefficients applied frequency component value for each frequency position, performs an inverse Fourier transform on the coefficient-applied block generated, and removes the overlapping portion from the coefficient-applied block after the inverse Fourier transform,
wherein the coefficients are a different value for each time position and are different for each frequency position.

3 more elements

An optical reception method comprising:

performing wavelength dispersion compensation for each subcarrier contained in a reception signal obtained by interfering a received optical signal and a local light emission;
and
compensating for a delay between reception signals at different subcarriers among the reception signals at subcarriers obtained by the wavelength dispersion compensation, delimiting, by each of the plurality of wavelength dispersion compensation units, a reception signal of the reception signals input into blocks each having a specific length such that an overlapping portion having a predetermined length between adjacent blocks is generated,
outputting, by each of the plurality of wavelength dispersion compensation units, the blocks delimited,
performing, by each of the plurality of wavelength dispersion compensation units, a Fourier transform for each of the blocks,
holding, by each of the plurality of wavelength dispersion compensation units, the blocks that are temporally consecutive after the Fourier transform,
applying, by each of the plurality of wavelength dispersion compensation units, coefficients defined according to a wavelength dispersion compensation amount in accordance with a frequency position and a delay amount in accordance with the frequency position and a time position to each of the blocks held,
generating, by each of the plurality of wavelength dispersion compensation units, a coefficients applied block by adding up a coefficients applied frequency component value for each frequency position,
performing, by each of the plurality of wavelength dispersion compensation units, an inverse Fourier transform on the coefficient-applied block generated, and removing, by each of the plurality of wavelength dispersion compensation units, the overlapping portion from the coefficient-applied block after the inverse Fourier transform,
wherein the coefficients are a different value for each time position and are different for each frequency position.

7 more elements

Dependencies are inferred from the claim text.