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Optical transmission distortion compensation device, optical transmission distortion compensation method, and communication device

A technology of distortion compensation and communication device, applied in optical fiber transmission, transmission system, elimination of distortion/chromatic dispersion, etc., can solve problems such as crosstalk and removal, and achieve the effect of compensating for constellation distortion

Active Publication Date: 2019-02-05
NTT ELECTORNICS CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

On the other hand, in the coherent detection method, if the frequencies of the transmitting laser and the local oscillator laser on the receiving side are not exactly matched, the residual carrier wave is not converted to DC at the power level on the receiving side and cannot pass through the DC module. circuit removal
[0008] In addition, in what is known as constellation distortion, there is IQ (In-phase Quadrature) crosstalk
When the phase difference between the in-phase (In-phase) component and the quadrature phase (Quadrature) component is not exactly 90° due to the bias voltage error of the optical modulator, IQ crosstalk occurs

Method used

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  • Optical transmission distortion compensation device, optical transmission distortion compensation method, and communication device
  • Optical transmission distortion compensation device, optical transmission distortion compensation method, and communication device
  • Optical transmission distortion compensation device, optical transmission distortion compensation method, and communication device

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Embodiment approach 1

[0034] figure 1 It is a diagram showing the receiving device of the coherent optical communication device according to Embodiment 1 of the present invention. The receiving device 1 converts the optical signal received from the optical fiber 2 into an electrical signal and performs digital processing.

[0035] In the receiving device 1, first, the polarization splitter 3 splits the optical signal into two orthogonally polarized components. These optical signals and the local light of the local light source 4 are input into the 90° hybrid circuit 5, 6, and a group of output lights obtained by causing the two lights to interfere with each other in the same phase and anti-phase, and a group of output lights obtained by orthogonal (90°) can be obtained. °) and anti-orthogonal (-90°) interference, a total of 4 output lights. These output lights are respectively converted into analog signals by photodiodes (not shown). These analog signals are converted into digital signals by the...

Embodiment approach 2

[0090] Figure 7 It is a diagram showing an optical transmission distortion compensation device according to Embodiment 2 of the present invention. A skew compensation unit 18 is provided between the IQ distortion compensation unit 12 and the carrier phase reproduction unit 13 . With the addition of the skew compensating section 18, the derivation formula of the coefficient in the coefficient calculating section 17 changes. Other structures are the same as those in Embodiment 1.

[0091] Figure 8 It is a figure which shows the skew compensation part of Embodiment 2 of this invention. The skew compensation unit 18 mainly performs skew compensation for compensating the delay difference between the I component signal and the Q component signal at the time of transmission. The skew compensating section 18 has: a filter 19 that performs skew compensation of the outputs of the I component compensating section 15 and the Q component compensating section 16; The filter coefficie...

Embodiment approach 3

[0127] Figure 9 It is a diagram showing an optical transmission distortion compensation device according to Embodiment 3 of the present invention. The adaptive equalization unit 9 and the phase variation compensation unit 11 calculate filter coefficients and compensation amounts for equalization processing and compensation processing, respectively, based on the error between the known signal and the received signal. For example, as the known signal of the adaptive equalization unit 9, a long-period known pattern signal for synchronization arranged at the head position of the packet data at the level of hundreds of symbols, arranged at the level of every several tens of symbols, can be used. A short-period, known pattern signal in the data ensemble. As the known signal of the phase fluctuation compensator 11, the above-mentioned short cycle and known pattern signal can be used.

[0128]IQ distortion remains in the uncompensated received signal, but the known signal does not ...

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Abstract

An I component compensation unit (15) calculates an I component in which a distortion has been compensated, by forming a first polynomial expressing the distortion of the I component based on an I component and a Q component of a quadrature modulation signal and multiplying each term of the first polynomial by a first coefficient. A Q component compensation unit (16) calculates a Q component in which a distortion has been compensated, by forming a second polynomial expressing the distortion of the Q component based on the I component and the Q component of the quadrature modulation signal andmultiplying each term of the second polynomial by a second coefficient. A coefficient calculation unit (17) calculates the first and second coefficients by comparing outputs of the I component compensation unit (15) and the Q component compensation unit (16) and a known signal.

Description

technical field [0001] The present invention relates to an optical transmission distortion compensation device, an optical transmission distortion compensation method and a communication device for quadrature modulation communication in data communication. Background technique [0002] In coherent optical communication, quadrature modulation in which amplitude modulation is independently performed on an in-phase component (In phase component: I component) and a quadrature phase component (Quadrature Phase component: Q component) is used. The transmission rate has been increased by multi-value modulation such as QPSK (Quadrature Phase Shift Keying: Quadrature Phase Shift Keying) and 16QAM (Quadrature Amplitude Modulation: Quadrature Amplitude Modulation). In order to further increase the speed, multi-value conversion to 64QAM and the like is also carried out. On the receiving side, after the optical demodulator converts the optical signal into an electrical signal and perfor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/01H04B10/2507H04B10/60H04L27/06
CPCH04L27/01H04L27/06H04B10/616H04B10/588H04B10/40H04B10/5161H04B10/58H04B10/6163
Inventor 大沼靖治山崎悦史野内裕之高椋智大大山胜一武井和人中村政则吉田光辉富泽将人
Owner NTT ELECTORNICS CORP
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