 receiving data of two polarization states orthogonal to each other from an Inphase/Quadrature (IQ) balance

converting the data of the two polarization states orthogonal to each other from timedomain data to frequencydomain data by adopting a discrete Fourier transform, with N=2^{t }and t being a natural number greater than 2, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k) respectively, k=0, 1, . . . , N−1, then
$Z\left(k\right)=\sum _{n=0}^{N1}z\left(n\right){W}_{N}^{\mathrm{nk}},k=0,1,\dots \phantom{\rule{0.8em}{0.8ex}},N1,\mathrm{and}$ $Z\left(k\right)=X\left(k\right)+i\xb7Y\left(k\right),$ wherein i^{2}=−1 
where
${W}_{N}={e}^{j\frac{2\pi}{N}},$ z(n) represents a sampled timedomain signal sequence, z(n)=x(n)+i·y(n), and consists of the data x(n) and y(n) of the two polarization states orthogonal to each other, and Z(k) is a frequencydomain signal corresponding to the sampled timedomain signal sequence z(n), where n=0, 1, . . . , N−1 
performing extraction of data from the frequencydomain data according to the following rules:
${X}^{U}\left[k\right]=X\left[k+\frac{N}{4}\frac{M}{2}\right],{X}^{L}\left[k\right]=X\left[k+\frac{3N}{4}\frac{M}{2}\right],\mathrm{and}$ ${Y}^{U}\left[k\right]=X\left[k+\frac{N}{4}\frac{M}{2}\right],{Y}^{L}\left[k\right]=X\left[k+\frac{3N}{4}\frac{M}{2}\right],$ where X^{U}[k] represents upper sideband data extracted from X(k), X^{L }[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),$M=\frac{N}{8},$ where k=0, 1, . . . , M−1  performing a linear combination operation on the extracted data from the frequencydomain data
 obtaining an argument of a CD value of the data of the two polarization states according to a result of the linear combination operation
 estimating the CD value according to the argument of the CD value of the data of the two polarization states
 and sending the CD value to a CD compensation, such that the CD compensation compensates for the CD value.
Chromatic dispersion detection method and device for optical transmission network and storage medium
Updated Time 12 June 2019
Patent Registration DataPublication Number
US10153847
Application Number
US15/506105
Application Date
08 April 2015
Publication Date
11 December 2018
Current Assignee
SANECHIPS TECHNOLOGY CO.,LTD.
Original Assignee (Applicant)
SANECHIPS TECHNOLOGY CO., LTD.
International Classification
H04B10/079,H04B10/58,H04B10/61,H04B17/00,H04B10/2513
Cooperative Classification
H04B10/6162,H04B10/58,H04B10/07951,H04B10/6161,H04B10/25133
Inventor
GUO, JIZHENG,YU, CHENG,ZHOU, HAITAO,ZENG, XIANJUN
Patent Images
This patent contains figures and images illustrating the invention and its embodiment.
Abstract
The disclosure discloses a Chromatic Dispersion (CD) detection method for an optical transmission network. Data of two polarization states orthogonal to each other is converted from timedomain data to frequencydomain data, extraction is performed on the frequencydomain data and a linear combination operation is performed on the extracted frequencydomain data, an argument of a CD value of the data of the two polarization states are obtained according to a result of the linear combination operation, and the CD value is estimated according to the argument of the CD value of the data of the two polarization states. The disclosure further discloses a CD detection device for the optical transmission network and a storage medium.
Claims
1. A Chromatic Dispersion (CD) estimation method for an optical transmission network comprising:
receiving data of two polarization states orthogonal to each other from an Inphase/Quadrature (IQ) balance; converting the data of the two polarization states orthogonal to each other from timedomain data to frequencydomain data by adopting a discrete Fourier transform, with N=2^{t }and t being a natural number greater than 2, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k) respectively, k=0, 1, . . . , N−1, then
wherein i^{2}=−1;
where
performing extraction of data from the frequencydomain data according to the following rules:
where X^{U}[k] represents upper sideband data extracted from X(k), X^{L }[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),
performing a linear combination operation on the extracted data from the frequencydomain data; obtaining an argument of a CD value of the data of the two polarization states according to a result of the linear combination operation; estimating the CD value according to the argument of the CD value of the data of the two polarization states; and sending the CD value to a CD compensation, such that the CD compensation compensates for the CD value.
2. The CD estimation method according to claim 1, wherein performing the linear combination operation on the extracted data from the frequencydomain data comprises:
step a: obtaining two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k]:
where k=0, 1, . . . , N−1;step b: performing conjugate multiplication on the two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }to obtain a CD subsequence R_{1}[k], R_{2}[k] and R_{3 }[k] in the three different directions:
R_{n}[k]=X_{n}^{(U)}[k]·conj{X_{n}^{(L)}[k]}, where conj(⋅) is a conjugate operation, k=0, . . . N−1 and n=1, 2, 3; step c: setting a first interval value as Δ_{1}=2 and a second interval value as Δ_{2}=32, and calculating accumulated values F_{1 }and F_{2 }corresponding to these two interval values in different directions according to R_{1}[k], R_{2}[k] and R_{3}[k]:
step d: performing lowpass filtering on a number T of accumulated values F_{1 }and a number M of accumulated values F_{2 }thus obtained to get F_{1 }and F_{2}:
where k1=0, 1, . . . , T−1, and k2=0, 1, . . . , M−1; and step e: constructing two registers Buffer1 and Buffer2 with a length L, wherein Buffer1 stores F_{1 }calculated for recent L times, Buffer2 stores F_{2 }calculated for recent L times, initial values of Buffer1 and Buffer2 are both a number L of zeros, data in the Buffer1 is summed to obtain F_{1}_{_}_{sum}, and data in Buffer2 is summed to obtain F_{2}_{_}_{sum}:
here, a value of L is selected from [16, 32, 64, 128].
3. The CD estimation method according to claim 2, wherein obtaining the argument of the CD value of the data of the two polarization states according to the result of the linear combination operation comprises: calculating arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states according to F_{1}_{_}_{sum }and F_{2}_{_}_{sum }respectively:
where both φ_{1 }and φ_{2 }belong to an interval [0,1).
4. The CD estimation method according to claim 3, wherein estimating the CD value according to the argument of the CD value of the data of the two polarization states comprises: obtaining a CD estimation coefficient φ_{1}″ according to the arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states, and estimating the CD value CD according to the CD estimation coefficient φ_{1}″:
CD=φ_{1}″×delta_CD, where delta_CD=1000×C×N_fft/(2×f^{2}×lambda^{2}), C is a light velocity in an optical fibre, N_fft is a discrete Fourier transform length, f is a symbol rate, and lambda is a wavelength.
5. A Chromatic Dispersion (CD) estimation device for an optical transmission network comprising:
a processor; and a memory for storing instructions executable by the processor;wherein the processor is configured to:
receive data of two polarization states orthogonal to each other from an Inphase/Quadrature (IQ) balance; convert the data of the two polarization states orthogonal to each other from timedomain data to frequencydomain data by adopting a discrete Fourier transform, with N=2^{t }and t being a natural number greater than 2, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k) respectively, k=0, 1, . . . , N−1, then
where
perform extraction of data from the frequencydomain data according to the following rules:
where X^{U}[k] represents upper sideband data extracted from X(k), X^{L }[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),
perform a linear combination operation on the extracted data from the frequencydomain data to obtain a result of the linear combination operation; obtain an argument of a CD value of the data of the two polarization states according to the result of the linear combination operation; estimate the CD value according to the argument of the CD value of the data of the two polarization states; and send the CD value to a CD compensation, such that the CD compensation compensates for the CD value.
6. The CD estimation device according to claim 5, wherein the processor is configured to:
1): obtain two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U)}as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k]:
where k=0, 1, . . . , N−1;2): perform conjugate multiplication on the two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }to obtain a CD subsequence R_{1}[k], R_{2 }[k] and R_{3}[k] in the three different directions:
R_{n}[k]=X_{n}^{(U)}[k]·conj{X_{n}^{(L)}[k]}, where conj(⋅) is a conjugate operation, k=0, . . . N−1 and n=1, 2, 3; 3): set a first interval value as Δ_{1}=2 and a second interval value as Δ_{2}=32, and calculate accumulated values F_{1 }and F_{2 }corresponding to these two interval values in different directions according to R_{1}[k], R_{2}[k] and R_{3}[k]:
4): perform lowpass filtering on a number T of accumulated values F_{1 }and a number M of accumulated values F_{2 }thus obtained to get F_{1 }and F_{2}:
where k1=0, 1, . . . , T−1, and k2=0, 1, . . . , M−1; and 5): construct two registers Buffer1 and Buffer2 with a length L, wherein Buffer1 stores F_{1 }calculated for recent L times, Buffer2 stores F_{2 }calculated for recent L times, initial values of Buffer1 and Buffer2 are both a number L of zeros, data in the Buffer1 is summed to obtain F_{1}_{_}_{sum}, and data in Buffer2 is summed to obtain F_{2}_{_}_{sum}.
7. The CD estimation device according to claim 6, wherein the processor is configured to calculate arguments φ_{1 }and φ_{2 }of the CD value the data of the two polarization states according to F_{1}_{_}_{sum }and F_{2}_{_}_{sum }respectively:
where both φ_{1 }and φ_{2 }belong to an interval [0,1).
8. The CD estimation device according to claim 7, wherein the processor is configured to obtain a CD estimation coefficient φ_{1}″ according to the arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states, and estimate the CD value CD according to the CD estimation coefficient φ_{1}″:
CD=φ_{1}″×delta_CD, where delta_CD=1000×C×N_fft/(2×f^{2}×lambda^{2}), C is a light velocity in an optical fibre, N_fft is a discrete Fourier transform length, f is a symbol rate, and lambda is a wavelength.
9. A nontransitory computer storage readable medium in which a computer program is stored, wherein when the computer program is executed, a processor is caused to:
receive data of two polarization states orthogonal to each other from an Inphase/Quadrature (IQ) balance; convert the data of the two polarization states orthogonal to each other from timedomain data to frequencydomain data by adopting a discrete Fourier transform, with N=2^{t }and t being a natural number greater than 2, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k) respectively, k=0, 1, . . . , N−1, then
wherein i^{2}=−1; where
perform extraction of data from the frequencydomain data according to the following rules:
where X^{U}[k] represents upper sideband data extracted from X(k), X^{L}[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),
perform a linear combination operation on the extracted data from the frequencydomain data; obtain an argument of a CD value of the data of the two polarization states according to a result of the linear combination operation; estimate the CD value according to the argument of the CD value of the data of the two polarization states; and send the CD value to a CD compensation, such that the CD compensation compensates for the CD value.
10. The nontransitory computer storage readable medium according to claim 9, wherein performing, by the processor, the linear combination operation on the extracted data from the frequencydomain data comprises:
step a: obtaining two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U)}as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k]:
where k=0, 1, . . . , N−1;step b: performing conjugate multiplication on the two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }to obtain a CD subsequence R_{1}[k], R_{2}[k] and R_{3}[k] in the three different directions:
R_{n}[k]=X_{n}^{(U)}[k]·conj{X_{n}^{(L)}[k]}, where conj(⋅) is a conjugate operation, k=0, . . . N−1 and n=1, 2, 3; step c: setting a first interval value as Δ_{1}=2 and a second interval value as Δ_{2}=32, and calculating accumulated values F_{1 }and F_{2 }corresponding to these two interval values in different directions according to R_{1}[k], R_{2}[k] and R_{3}[k]:
step d: performing lowpass filtering on a number T of accumulated values F_{1 }and a number M of accumulated values F_{2 }thus obtained to get F_{1 }and F_{2}:
where k1=0, 1, . . . , T−1, and k2=0, 1, . . . , M−1; and step e: constructing two registers Buffer1 and Buffer2 with a length L, wherein Buffer1 stores F_{1 }calculated for recent L times, Buffer2 stores F_{2 }calculated for recent L times, initial values of Buffer1 and Buffer2 are both a number L of zeros, data in the Buffer1 is summed to obtain F_{1}_{_}_{sum}, and data in Buffer2 is summed to obtain F_{2}_{_}_{sum}:
here, a value of L is selected from [16, 32, 64, 128].
11. The nontransitory computer storage readable medium according to claim 10, wherein obtaining, by the processor, the argument of the CD value of the data of the two polarization states according to the result of the linear combination operation comprises: calculating arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states according to F_{1}_{_}_{sum }and F_{2}_{_}_{sum }respectively:
where both φ_{1 }and φ_{2 }belong to an interval [0,1).
12. The nontransitory computer storage readable medium according to claim 11, wherein estimating, by the processor, the CD value according to the argument of the CD value of the data of the two polarization states comprises:
obtaining a CD estimation coefficient φ_{1}″ according to the arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states, and estimating the CD value CD according to the CD estimation coefficient φ_{1}″:
CD=φ_{1}″×delta_CD, where delta_CD=1000×C×N_fft/(2×f^{2}×lambda^{2}), C is a light velocity in an optical fibre, N_fft is a discrete Fourier transform length, f is a symbol rate, and lambda is a wavelength.
Claim Tree

11. A Chromatic Dispersion (CD) estimation method for an optical transmission network comprising:

22. The CD estimation method according to claim 1, wherein
 performing the linear combination operation on the extracted data from the frequencydomain data comprises:

3. The CD estimation method according to claim 2, wherein
 obtaining the argument of the CD value of the data of the two polarization states according to the result of the linear combination operation comprises:

55. A Chromatic Dispersion (CD) estimation device for an optical transmission network comprising:
 a processor
 and a memory for storing instructions executable by the processor
 wherein the processor is configured to: receive data of two polarization states orthogonal to each other from an Inphase/Quadrature (IQ) balance

convert the data of the two polarization states orthogonal to each other from timedomain data to frequencydomain data by adopting a discrete Fourier transform, with N=2^{t }and t being a natural number greater than 2, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k) respectively, k=0, 1, . . . , N−1, then
$Z\left(k\right)=\sum _{n=0}^{N1}z\left(n\right){W}_{N}^{\mathrm{nk}},k=0,1,\dots \phantom{\rule{0.8em}{0.8ex}},N1,\mathrm{and}$ $Z\left(k\right)=X\left(k\right)+i\xb7Y\left(k\right),$ where${W}_{N}={e}^{j\frac{2\pi}{N}},$ z(n) represents a sampled timedomain signal sequence, z(n)=x(n)+i·y(n), and consists of the data x(n) and y(n) of the two polarization states orthogonal to each other, and Z(k) is a frequencydomain signal corresponding to the sampled timedomain signal sequence z(n), where n=0, 1, . . . , N−1 
perform extraction of data from the frequencydomain data according to the following rules:
${X}^{U}\left[k\right]=X\left[k+\frac{N}{4}\frac{M}{2}\right],{X}^{L}\left[k\right]=X\left[k+\frac{3N}{4}\frac{M}{2}\right],\mathrm{and}$ ${Y}^{U}\left[k\right]=X\left[k+\frac{N}{4}\frac{M}{2}\right],{Y}^{L}\left[k\right]=X\left[k+\frac{3N}{4}\frac{M}{2}\right],$ where X^{U}[k] represents upper sideband data extracted from X(k), X^{L }[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),$M=\frac{N}{8},$ where k=0, 1, . . . , M−1  perform a linear combination operation on the extracted data from the frequencydomain data to obtain a result of the linear combination operation
 obtain an argument of a CD value of the data of the two polarization states according to the result of the linear combination operation
 estimate the CD value according to the argument of the CD value of the data of the two polarization states
 and send the CD value to a CD compensation, such that the CD compensation compensates for the CD value.

6. The CD estimation device according to claim 5, wherein

the processor is configured to:
1): obtain two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U)}as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k]:
$\{\begin{array}{c}{X}_{1}^{\left(U\right)}\left[k\right]=\sqrt{2}{X}^{\left(U\right)}\left[k\right]\\ {X}_{2}^{\left(U\right)}\left[k\right]={X}^{\left(U\right)}\left[k\right]+\sqrt{1}\xb7{Y}^{\left(U\right)}\left[k\right]\\ {X}_{3}^{\left(U\right)}\left[k\right]={X}^{\left(U\right)}\left[k\right]+{Y}^{\left(U\right)}\left[k\right]\end{array}\text{}\{\begin{array}{c}{X}_{1}^{\left(L\right)}\left[k\right]=\sqrt{2}{X}^{\left(L\right)}\left[k\right]\\ {X}_{2}^{\left(L\right)}\left[k\right]={X}^{\left(L\right)}\left[k\right]+\sqrt{1}\xb7{Y}^{\left(L\right)}\left[k\right]\\ {X}_{3}^{\left(L\right)}\left[k\right]={X}^{\left(L\right)}\left[k\right]+{Y}^{\left(L\right)}\left[k\right]\end{array}$ where k=0, 1, . . . , N−1;2): perform conjugate multiplication on the two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }to obtain a CD subsequence R_{1}[k], R_{2 }[k] and R_{3}[k] in the three different directions: R_{n}[k]=X_{n}^{(U)}[k]·conj{X_{n}^{(L)}[k]}, where conj(⋅) is a conjugate operation, k=0, . . . N−1 and n=1, 2, 3; 3): set a first interval value as Δ_{1}=2 and a second interval value as Δ_{2}=32, and calculate accumulated values F_{1 }and F_{2 }corresponding to these two interval values in different directions according to R_{1}[k], R_{2}[k] and R_{3}[k]:${F}_{1}=\sum _{n=1}^{3}\phantom{\rule{0.3em}{0.3ex}}\sum _{k=0}^{N{\Delta}_{1}}\phantom{\rule{0.3em}{0.3ex}}{R}_{n}\left[k\right]\xb7\mathrm{conj}\left({R}_{n}\left[k+{\Delta}_{1}\right]\right),\mathrm{and}$ ${F}_{2}=\sum _{n=1}^{3}\phantom{\rule{0.3em}{0.3ex}}\sum _{k=0}^{N{\Delta}_{2}}\phantom{\rule{0.3em}{0.3ex}}{R}_{n}\left[k\right]\xb7\mathrm{conj}\left({R}_{n}\left[k+{\Delta}_{2}\right]\right);$ 4): perform lowpass filtering on a number T of accumulated values F_{1 }and a number M of accumulated values F_{2 }thus obtained to get F_{1 }and F_{2}:$\stackrel{\_}{{F}_{1}}=\sum _{k\phantom{\rule{0.3em}{0.3ex}}1=0}^{T1}\phantom{\rule{0.3em}{0.3ex}}{F}_{1}\left[k\right],\mathrm{and}$ $\stackrel{\_}{{F}_{2}}=\sum _{k\phantom{\rule{0.3em}{0.3ex}}2=0}^{M1}\phantom{\rule{0.3em}{0.3ex}}{F}_{2}\left[k\phantom{\rule{0.3em}{0.3ex}}2\right],$ where k1=0, 1, . . . , T−1, and k2=0, 1, . . . , M−1; and 5): construct two registers Buffer1 and Buffer2 with a length L, wherein

the processor is configured to:
1): obtain two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U)}as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k]:

99. A nontransitory computer storage readable medium in which
 a computer program is stored, wherein

10. The nontransitory computer storage readable medium according to claim 9, wherein
 performing, by the processor, the linear combination operation on the extracted data from the frequencydomain data comprises:
Description
TECHNICAL FIELD
The disclosure relates to an optical communication technology, and more particularly to a Chromatic Dispersion (CD) detection method and device for an optical transmission network and a storage medium.
BACKGROUND
In an optical transmission network, with increase of a transmission length and a transmission baud rate, for example, in a 100 Gbps ultralongdistance optical transmission network, CD generated an optical signal in a transmission process becomes increasingly serious, and the CD may cause distortion of the transmitted signal, thereby resulting in a transmission error. In order to eliminate influence of the CD, it is necessary to compensate for the CD, and the key for CD compensation is to accurately estimate a CD value.
SUMMARY
In order to solve the existing technical problem, embodiments of the disclosure are desired to provide a CD detection method and device for an optical transmission network and a storage medium.
The technical solutions of the embodiments of the disclosure are implemented as follows.
The embodiments of the disclosure provide a CD detection method for an optical transmission network comprising:
converting data of two polarization states orthogonal to each other from timedomain data to frequencydomain data, performing extraction on the frequencydomain data and performing a linear combination operation on the extracted frequencydomain data, obtaining an argument of a CD value of the data of the two polarization states according to a result of the linear combination operation, and estimating the CD value according to the argument of the CD value of the data of the two polarization states.
The embodiments of the disclosure further provide a CD detection device for an optical transmission network comprising: a data conversion module, a data extraction module, a linear combination operation module, an argument acquisition module and a CD estimation module,
the data conversion module is configured to convert data of two polarization states orthogonal to each other from timedomain data to frequencydomain data;
the data extraction module is configured to perform extraction on the frequencydomain data, and send the extracted frequencydomain data to the linear combination operation module;
the linear combination operation module is configured to perform a linear combination operation on the extracted frequencydomain data, and send a result of the linear combination operation to the argument acquisition module;
the argument acquisition module is configured to obtain an argument of a CD value of the data of the two polarization states according to the result of the linear combination operation, and send the argument of the CD value to the CD estimation module; and
the CD estimation module is configured to estimate the CD value according to the argument of the CD value of the data of the two polarization states.
The embodiments of the disclosure further provide a computer storage medium in which a computer program is stored for execution of the above CD detection method for the optical transmission network.
The embodiments of the disclosure provide the CD detection method and device for the optical transmission network and the storage medium, data of two polarization states orthogonal to each other is converted from timedomain data to frequencydomain data, extraction is performed on the frequencydomain data and a linear combination operation is performed on the frequencydomain data, an argument of a CD value of the data of the two polarization states is obtained according to a result of the linear combination operation, and the CD value is estimated according to the argument of the CD value of the data of the two polarization states; as such, an electric domain estimation may be performed on CD of the optical transmission network to implement CD detection for the optical transmission network.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of implementation of a flow of a CD detection method for an optical transmission network according to an embodiment of the disclosure;
FIG. 2 is a schematic diagram of implementation of a structure of a CD detection device for an optical transmission network according to an embodiment of the disclosure; and
FIG. 3 is a schematic diagram of a position of a CD detection device in an optical transmission network according to an embodiment of the disclosure.
DETAILED DESCRIPTION
In the embodiments of the disclosure, data of two polarization states orthogonal to each other is converted from timedomain data to frequencydomain data, extraction is performed on the frequencydomain data and a linear combination operation is performed on the extracted frequencydomain data, an argument of a CD value of the data of the two polarization states is obtained according to a result of the linear combination operation, and the CD value is estimated according to the argument of the CD value of the data of the two polarization states.
The disclosure will be further described in detail below with reference to the drawings and specific embodiments.
The embodiments of the disclosure implement a CD detection method for an optical transmission network. As shown in FIG. 1, the method includes the following steps.
In Step 101: data of two polarization states orthogonal to each other is converted from timedomain data to frequencydomain data.
In the step, a special algorithm of discrete Fourier transform, i.e. Fast Fourier Transform (FFT), is adopted for implementation, with N=2^{t }and t being a natural number, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k), k=0, 1, . . . , N−1, then
where
z(n) represents a sampled timedomain signal sequence, z(n)=x(n)+i·y(n), and consists of the data x(n) and y(n) of the polarization states in two orthogonal dimensions, and Z(k) is a frequencydomain signal corresponding to the sequence z(n).
In Step 102: extraction is performed on the frequencydomain data.
In the step, the data is extracted from the frequencydomain data according to the following rules:
where X^{U}[k] represents upper sideband data extracted from X(k), X^{L}[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),
and M may be also designated according to the specific precision requirement, where k=0, 1, . . . , M−1.
In Step 103: a linear combination operation is performed on the extracted frequencydomain data.
Here, the following steps are included.
In Step 103a: two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions are obtained according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k]:
where k=0, 1, . . . , N−1.
In Step 103b: conjugate multiplication is performed on the two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in the three different directions to obtain a CD subsequence R_{1}[k], R_{2}[k] and R_{3}[k] in the three different directions:
R_{n}[k]=X_{n}^{(U)}[k]·conj{X_{n}^{(L)}[k]},
where conj(⋅) is a conjugate operation, k=0, . . . N−1 and n=1, 2, 3.
In Step 103c: a first interval value is set as Δ_{1}=2 and a second interval value is set as Δ_{2}=32, and accumulated values F_{1 }and F_{2 }corresponding to these two interval values in different directions are calculated according to R_{1}[k], R_{2}[k] and R_{3}[k]:
In Step 103d: lowpass filtering is performed on a number T of accumulated values F_{1 }and a number M of accumulated values F_{2 }thus obtained to get F_{1} and F_{2}:
where k1=0, 1, . . . , T−1, and k2=0, 1, . . . , M−1.
In Step 103e: two registers Buffer1 and Buffer2 with a length L are constructed, Buffer1 stores F_{1} calculated for recent L times, Buffer2 stores F_{2} calculated for recent L times, initial values of Buffer1 and Buffer2 are both a number L of zeros, data in the Buffer1 is summed to obtain F_{1}_{_}_{sum}, and data in Buffer2 is summed to obtain F_{2}_{_}_{sum}:
here, a value of L may be configured, and may be selected from [16, 32, 64, 128], and a default value of L is 16.
In Step 104: the argument of the CD value of the data of the two polarization states is obtained according to the result of the linear combination operation;
particularly, the arguments φ_{1 }and φ_{2 }of the CD values of the data of the two polarization states are calculated respectively according to F_{1}_{_}_{sum }and F_{2}_{_}_{sum}:
where both φ_{1 }and φ_{2 }belong to an interval [0,1).
In Step 105: the CD value is estimated according to the argument of the CD value of the data of the two polarization states,
particularly, a CD estimation coefficient φ_{1}′ is obtained according to the arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states, and a specific process is as follows:
m=floor(φ_{1}×16), and
u=φ_{1}×16−m,
where floor(⋅) represents rounding down;
φ_{2}u=φ_{2}−u, and
when φ_{2}u≥0.5, u′=φ_{2}−1;
when φ_{2}u<−0.5, u′=φ_{2}+1; and
when −0.5≤φ_{2}u<0.5, u′=φ_{2};
φ_{1}′=m+u′,
φ_{1}′=φ_{1}′/32, and
if φ_{1}″≥0.25, a value obtained by φ_{1}″−0.5 is reassigned to φ_{1}″; and
the CD value CD is estimated according to the CD estimation coefficient φ_{1}″:
CD=φ_{1}″×delta_CD,
where delta_CD=1000×C×N_fft/(2×f^{2}×lambda^{2}), C is a light velocity in an optical fibre, N_fft is an FFT transformation length, f is a symbol rate, lambda is a wavelength, and for specific values, refer to Table 1.
In order to implement the abovementioned method, the disclosure further provides a CD detection device for an optical transmission network. As shown in FIG. 2, the device includes a data conversion module 21, a data extraction module 22, a linear combination operation module 23, an argument acquisition module 24 and a CD estimation module 25, in the device:
the data conversion module 21 is configured to convert data of two polarization states orthogonal to each other from timedomain data to frequencydomain data;
the data extraction module 22 is configured to perform extraction on the frequencydomain data, and send the extracted frequencydomain data to the linear combination operation module 23;
the linear combination operation module 23 is configured to perform a linear combination operation on the extracted frequencydomain data, and send a result of the linear combination operation to the argument acquisition module 24;
the argument acquisition module 24 is configured to obtain an argument of a CD value of the data of the two polarization states according to the result of the linear combination operation, and send the argument of the CD value to the CD estimation module 25; and
the CD estimation module 25 is configured to estimate the CD value according to the argument of the CD value of the data of the two polarization states.
The data conversion module 21 is specifically configured to convert the data of the two polarization states into the frequencydomain data by adopting a discrete Fourier transform, with N=2^{t }and t being a natural number, and the frequencydomain data converted from the data of the two polarization states being set as X(k) and Y(k) respectively, k=0, 1, . . . , N−1, then:
where
z(n) represents a sampled timedomain signal sequence, z(n)=x(n)+i·y(n), and consists of the data x(n) and y(n) of the polarization states in two dimensions orthogonal to each other, and Z(k) is a frequencydomain signal corresponding to the sequence z(n).
The data extraction module 22 is specifically configured to extract data from the frequencydomain data according to the following rules:
where X^{U}[k] represents upper sideband data extracted from X(k), X^{L}[k] represents lower sideband data extracted from X(k), Y^{U}[k] represents upper sideband data extracted from Y(k), Y^{L}[k] represents lower sideband data extracted from Y(k),
and M may be also designated according to the specific precision requirement, where k=0, 1, . . . , M−1.
The linear combination operation module 23 is specifically configured to:
1): obtain two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in three different directions according to X^{U}[k], X^{L}[k], Y^{U}[k] and Y^{L}[k], estimation of the sequences in the three different directions can avoid influence of polarization mode dispersion on CD estimation:
where k=0, 1, . . . , N−1;
2): perform conjugate multiplication on the two groups of sequences X_{1}^{(U)}, X_{2}^{(U) }and X_{3}^{(U) }as well as X_{1}^{(L)}, X_{2}^{(L) }and X_{3}^{(L) }in the three different directions to obtain a CD subsequence R_{1}[k], R_{2}[k] and R_{3}[k] in the three different directions:
R_{n}[k]=X_{n}^{(U)}[k]·conj{X_{n}^{(L)}[k]},
where conj(⋅) is a conjugate operation, k=0, . . . N−1 and n=1, 2, 3;
3): set a first interval value as Δ_{1}=2 and a second interval value as Δ_{2}=32, and calculate accumulated values F_{1 }and F_{2 }corresponding to these two interval values in different directions according to R_{1}[k], R_{2}[k] and R_{3}[k]:
4): perform lowpass filtering on a number T of accumulated values F_{1 }and a number M of accumulated values F_{2 }thus obtained to get F_{1} and F_{2}:
where k1=0, 1, . . . , T−1, and k2=0, 1, . . . , M−1; and
5): construct two registers Buffer1 and Buffer2 with a length L, Buffer1 stores F_{1} calculated for recent L times, Buffer2 stores F_{2} calculated for recent L times, initial values of Buffer1 and Buffer2 are both a number L of zeros, data in the Buffer1 is summed to obtain F_{1}_{_}_{sum}, and data in Buffer2 is summed to obtain F_{2}_{_}_{sum}.
The argument acquisition module 24 is specifically configured to calculate the arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states according to F_{1}_{_}_{sum }and F_{2}_{_}_{sum }respectively:
where both φ_{1 }and φ_{2 }belong to an interval [0,1).
The CD estimation module 25 is specifically configured to obtain a CD estimation coefficient φ_{1}″ according to the arguments φ_{1 }and φ_{2 }of the CD value of the data of the two polarization states, and estimate the CD value CD according to the CD estimation coefficient φ_{1}′:
CD=φ_{1}″×delta_CD,
where delta_CD=1000×C×N_fft/(2×f^{2}×lambda^{2}), C is a light velocity in an optical fibre, N_fft is an FFT transformation length, f is a symbol rate, and lambda is a wavelength.
A position of the CD detection device for the optical transmission network in the optical transmission network is shown in FIG. 3. After an optical signal passes through an Optical Fibre Amplifier (Erbiumdoped Optical Fibre Amplifier, EDFA), a hybrid optical amplifier, a Balanced Photodiode Detector (BPD), an AnaloguetoDigital Converter (ADC), an Inphase/Quadrature (IQ) balance, the data of the two polarization states orthogonal to each other is transmitted to the CD detection device (CD monitor) and CD compensation of the optical transmission network, the CD monitor sends the estimated CD value to the CD compensation, the CD compensation compensates for the CD value for other signal processing, and the optical signal is sent to a userside interface after passing through a Forward Error Corrector (FEC) and a framer.
If being implemented in form of a software function module and sold or used as an independent product, the CD detection method for the optical transmission network according to the embodiments of the disclosure may also be stored in a computerreadable storage medium. Based on such an understanding, the technical solutions of the embodiments of the disclosure naturally or parts contributing to a conventional art may be embodied in form of a software product, and the computer software product is stored in a storage medium, including a plurality of instructions to enable a piece of computer equipment (which may be a personal computer, a server, network equipment or the like) to execute all or part of the method of each embodiment of the disclosure. The storage medium includes various media capable of storing program codes such as a U disk, a mobile hard disk, a ReadOnly Memory (ROM), a magnetic disk or an optical disk. Therefore, the embodiments of the disclosure are not limited to any specific hardware and software combination.
Correspondingly, the embodiments of the disclosure further provide a computer storage medium in which a computer program is stored for execution of the CD detection method for the optical transmission network according to the embodiments of the disclosure.
What are described above are only the particular embodiments of the disclosure and not intended to limit the scope of protection of the disclosure. Any modifications, equivalent replacements, improvements and the like made within the spirit and principle of the disclosure shall fall within the scope of protection of the disclosure.
INDUSTRIAL APPLICABILITY
From each embodiment of the disclosure, the data of the two polarization states orthogonal to each other is converted into the frequencydomain data and a linear combination operation is performed, the argument of the CD value of the data of the two polarization states are obtained, and the CD value is estimated according to the argument of the CD value. Therefore, electric domain estimation may be performed on CD of the optical transmission network to implement CD detection of the optical transmission network.
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