CN106850497A - A kind of method of coherent-light OFDM communication system cascade compensation - Google Patents

A kind of method of coherent-light OFDM communication system cascade compensation Download PDF

Info

Publication number
CN106850497A
CN106850497A CN201710032907.XA CN201710032907A CN106850497A CN 106850497 A CN106850497 A CN 106850497A CN 201710032907 A CN201710032907 A CN 201710032907A CN 106850497 A CN106850497 A CN 106850497A
Authority
CN
China
Prior art keywords
transmitting end
communication system
phase
ofdm communication
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN201710032907.XA
Other languages
Chinese (zh)
Other versions
CN106850497B (en
Inventor
李超
徐正元
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University of Science and Technology of China USTC
Original Assignee
University of Science and Technology of China USTC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by University of Science and Technology of China USTC filed Critical University of Science and Technology of China USTC
Priority to CN201710032907.XA priority Critical patent/CN106850497B/en
Publication of CN106850497A publication Critical patent/CN106850497A/en
Application granted granted Critical
Publication of CN106850497B publication Critical patent/CN106850497B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/32—Carrier systems characterised by combinations of two or more of the types covered by groups H04L27/02, H04L27/10, H04L27/18 or H04L27/26
    • H04L27/34—Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
    • H04L27/38—Demodulator circuits; Receiver circuits
    • H04L27/3845—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier
    • H04L27/3854—Demodulator circuits; Receiver circuits using non - coherent demodulation, i.e. not using a phase synchronous carrier using a non - coherent carrier, including systems with baseband correction for phase or frequency offset
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/60—Receivers
    • H04B10/61—Coherent receivers
    • H04B10/616—Details of the electronic signal processing in coherent optical receivers
    • H04B10/6165—Estimation of the phase of the received optical signal, phase error estimation or phase error correction
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2689—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation
    • H04L27/2695—Link with other circuits, i.e. special connections between synchronisation arrangements and other circuits for achieving synchronisation with channel estimation, e.g. determination of delay spread, derivative or peak tracking

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Optical Communication System (AREA)

Abstract

The invention discloses a kind of method of coherent-light OFDM communication system cascade compensation, the transmitting terminal in coherent-light OFDM communication system first designs pilot sub-carrier allocative decision；The laser phase noise of the transmitting terminal is compensated using phase conjugation pilot aided method in the receiving terminal of coherent-light OFDM communication system；The IQ amplitudes and the unbalance in phase factor of the transmitting terminal are further estimated using frequency domain second order algorithm for estimating in the receiving terminal；The IQ for further eliminating the transmitting terminal mismatches the system performance degradation for causing, and the signal to noise ratio of signal is received to be lifted.The method can solve the problem that the influence that laser phase noise is demodulated to signal in relevant optical OFDM system, estimates and compensate for transmitting terminal IQ unbalance factors, improve Transmission system performance.

Description

Cascade compensation method in coherent light OFDM communication system
Technical Field
The invention relates to the technical field of optical communication systems, in particular to a method for cascade compensation in a coherent optical OFDM communication system.
Background
At present, coherent detection becomes the first choice of a high-speed long-distance optical transmission system, single carrier 100G coherent reception is already put into commercial use, and a coherent optical OFDM communication technology is a powerful alternative for a future 400G and 1T optical transmission system. OFDM technology has high tolerance to fiber Chromatic Dispersion (CD) and Polarization Mode Dispersion (PMD), and is easily combined with high-order modulation formats (e.g., m-QAM and m-PSK) to achieve high spectral efficiency. However, coherent detection is particularly sensitive to phase noise caused by laser line width, and especially, the OFDM signal has a long symbol period, and the phase noise will seriously affect and deteriorate system performance, so strict digital domain tracking, estimation and compensation are required at the receiving end of coherent detection.
Meanwhile, due to the inherent characteristics of signal modulation and demodulation of coherent optical communication, the I path signal and the Q path signal are strictly required to be orthogonal to each other theoretically, and the amplitudes of the two paths are required to be equal. In practical applications, however, the mismatch of the bias points of the IQ modulators, the mismatch of the I/Q two-way cables, the non-ideal 90 ° optical mixer, the difference of the responsivity of the photodiodes, etc. all cause the mismatch of the amplitude and phase of the received signals. The phase and amplitude mismatch of the modulation signal is called IQ imbalance, and the IQ imbalance includes a transmitting IQ imbalance and a receiving IQ imbalance, and the performance of the system is seriously affected by the IQ imbalance of the transmitting end or the receiving end.
Disclosure of Invention
The invention aims to provide a method for cascade compensation in a coherent light OFDM communication system, which solves the problem that the phase noise of a laser in the coherent light OFDM system affects signal demodulation, estimates and compensates an IQ imbalance factor of a transmitting end, and improves the transmission performance of the system.
A method of cascade compensation in a coherent optical OFDM communication system, the method comprising:
step 1, designing a pilot frequency subcarrier distribution scheme at a transmitting end of a coherent light OFDM communication system;
step 2, compensating the laser phase noise of the transmitting end by adopting a phase conjugate pilot frequency auxiliary method at the receiving end of the coherent light OFDM communication system;
step 3, estimating IQ amplitude and phase imbalance factors of the transmitting end at the receiving end by further adopting a frequency domain second-order estimation algorithm;
and step 4, further eliminating system performance deterioration caused by IQ mismatching of the transmitting end so as to improve the signal-to-noise ratio of the received signal.
In the step 1:
the designed pilot subcarrier allocation scheme comprises: local subcarrier allocation and interleaved subcarrier allocation.
In the step 2, the process of compensating the laser phase noise at the transmitting end by using the phase conjugate pilot frequency aided method specifically includes:
multiplying each pilot subcarrier by a phase quantityφmIs the common phase error caused by the laser linewidth;
the expression of the estimated value of the public phase error obtained by using the conjugate pilot frequency sequence designed by the transmitting end is as follows:
wherein arg (·) represents the phase of the pilot sequence after multiplication,is the common phase error value estimated by the pilot frequency sequence;
then multiplying the signal sub-carrier of the coherent optical OFDM communication systemThereby removing the effect of laser phase noise.
In step 3, the estimated IQ amplitude and phase imbalance factor expression of the transmitting end is:
wherein, and Δ φ respectively represent IQ amplitude and phase imbalance factors of the transmitting end;
c is a known constant, NPFor the number of pilot frequency sub-carriers, I and Q represent two paths of signals at the transmitting end of the coherent optical communication system, rIAnd rQAnd the signals of the I path and the Q path of the receiving end are shown.
In the step 4, the process of eliminating system performance degradation caused by IQ mismatch at the transmitting end specifically includes:
suppose that the I path and the Q path of a coherent optical communication system transmitting end signal are S respectivelyIAnd SQAnd if the I/Q two paths of amplitude and phase imbalance and delta phi of the transmitting end exist, the signal expression of the receiving end is obtained as follows:
the final compensated signal expression is
Wherein,
according to the technical scheme provided by the invention, the method solves the influence of laser phase noise on signal demodulation in a coherent light OFDM system, estimates and compensates IQ imbalance factors of a transmitting terminal, and improves the transmission performance of the system.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on the drawings without creative efforts.
Fig. 1 is a schematic flowchart of a method for cascade compensation in a coherent optical OFDM communication system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a pilot subcarrier design according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
Firstly, the influence of transmitting end IQ imbalance and receiving end IQ imbalance on received signals in a coherent optical communication system is explained:
assuming that there is a transmit-side phase mismatch factor θtAnd amplitude mismatch factortAfter passing through the optical IQ modulator, the output electric field strength expression is as follows:
wherein,is the electric field strength, omega, of the input laserSAndrespectively representing the initial angular frequency and phase of the laser at the transmitting end. In the ideal case, θt＝0，tWhen the output electric field strength becomes E at 1out(t)＝Ein(t)·(IS+jQS)。
A coherent receiver based on 3dB coupler is composed of 4 3dB couplers and a 90 DEG phase shifter, and for the sake of simplicity and no loss of generality, the amplitude of the coupler C1 is assumed to existDegree mismatch factorr(i.e., the coupling coefficient of the coupler) the remaining 3 couplers are in an ideal state with a phase mismatch factor θr. Coupling coefficient of a 3dB coupler in an ideal caserWhen 1/2, the transfer function can be expressed as:
the electric field transfer function through couplers C1, C2, C3 and C4 are expressed as:
the 4 formulas are cascaded to obtain an input signal electric field, a local oscillator signal electric field and an output E1(t)、E2(t)、E3(t) and E4The relationship of (t) is:
after the receiver is balanced, the expression of the output photocurrent can be obtained as follows:
wherein,is the responsivity of a photodiode, ideally in coherent detectionThe electric field expression obtained by solving equation (9) is substituted for equations (10) and (11) without considering the case where the responsivity of the photodiode does not match:
further simplification yields an expression of:
()*denotes conjugation by X (t) + X*The properties of (t) ═ 2Re { x (t) } can be simplified as shown below
Assuming that the influence of noise is not taken into account, ES(t) is the intensity of the optical electric field of the carried signal after the optical fiber transmission, the expression of the intensity of the electric field is shown as the formula (3), and the expression of the intensity of the electric field of the local oscillator isωLOAndrespectively, the initial angular frequency and phase of the local oscillator.
Will ES(t) and ELOThe expression of (t) can be substituted for the formulae (16) and (17)
Wherein,when θ is 0 under the condition that the signal laser and the local oscillator laser have the same frequency and no phase noise, equations (18) and (19) are rewritten as follows:
the above equation is a relational expression between the signals of the transmitting end I path and Q path and the signals of the receiving end under the condition of IQ imbalance, and can be expressed as follows in a matrix form:
in the ideal case, θt＝0，θr＝0，t＝1，Can be substituted by formula (22)
At this time, the I and Q paths are perfectly orthogonal and equal in amplitude.
Starting from the OFDM signal, when IQ imbalance exists at the transmitting end, the following derivation procedure can be obtained:
at the transmitting end, the OFDM baseband signal is x (t), and the expression of the mth symbol of the time domain obtained after IDFT conversion is as follows
Where N is the number of subcarriers of the OFDM signal, dt[k]Denotes the k sub-carrier, TSIs the OFDM symbol period, fkIs the frequency of the kth subcarrier, and the orthogonality requirement f of each subcarrier is ensuredk＝(k-1)/TS。
At the receiving end, after DFT, transform to frequency domain, then the expression of k sub-carrier is
w[m]The received mth OFDM symbol is represented by w (t) z (t), z (t) x (t), and z (t) is the received OFDM baseband signal, and the receiving end d is obtained without considering IQ imbalance and channel noiser[k]Equal to the transmitting end value dt[k]。
Assuming that there are amplitude and phase mismatch factors of the transmitting end, which are respectively expressed by variables and sums, the time domain baseband signal of the receiving end is affected by IQ imbalance of the transmitting end, and the expression is rewritten as follows:
w(t)＝μz(t)+λz*(t) (26)
wherein distortion parameters μ and λ due to the IQ imbalance at the transmitting end are introduced, which are related to the sum of the magnitude and phase mismatch at the transmitting end, μ ═ cos () + jsin (), λ ═ cos () -j sin ().
When the I and Q paths of the transmitting terminal are in an equilibrium state, equation (26) is equal to 0 and 0, and μ is equal to 1 and λ is equal to 0.
Therefore, in the presence of the transmitting end IQ imbalance, the expression of the k sub-carrier of the received frequency domain OFDM signal becomes
When noise is not considered, z (t) x (t), thenIt is substituted by formula (27) to obtain
Wherein,is thatMirror image of (a).
When there is IQ imbalance at the transmitting end, the OFDM subcarrier generates a mirror image by taking the optical carrier at the transmitting end as a symmetric center; similarly, when there is IQ imbalance at the receiving end, the received OFDM sub-carriers will generate a mirror image centered around the local oscillator frequency. Therefore, due to the interference of the subcarrier images at the symmetrical positions, the constellation diagram of the modulated signal is distorted, which causes the interference between the carriers, seriously affects and reduces the transmission performance of the signal.
The following describes an embodiment of the present invention in further detail with reference to the accompanying drawings, and fig. 1 is a schematic flow chart of a method for cascade compensation in a coherent optical OFDM communication system according to the embodiment of the present invention, where the method includes:
step 1, designing a pilot frequency subcarrier distribution scheme at a transmitting end of a coherent light OFDM communication system;
in step 1, the designed pilot subcarrier allocation scheme includes: local subcarrier allocation and interleaved subcarrier allocation.
Fig. 2 is a schematic diagram of a pilot subcarrier design scheme provided in an embodiment of the present invention, where a denotes a local subcarrier allocation scheme and b denotes an interleaved subcarrier allocation scheme, specifically:
suppose the number of pilot subcarriers is 2NPThe two-phase alternating current DC power supply is symmetrically distributed on two sides with a direct current component DC as a center, and the following relation is satisfied:
assuming that the DC component DC is marked with 0 position, N on the left of DCPThe pilot is located at the negative half shaft and the DC right NPThe pilots are located on the positive half axis. The phase difference of adjacent pilot frequency sub-carriers on two half shafts is pi/2, and the corresponding pilot frequency on the positive half shaft and the negative half shaft meets the phase conjugationIs described.
Step 2, compensating the laser phase noise of the transmitting end by adopting a phase conjugate pilot frequency auxiliary method at the receiving end of the coherent light OFDM communication system;
in step 2, the process of compensating the laser phase noise at the transmitting end by using the phase conjugate pilot frequency assistance method specifically includes:
multiplying each pilot subcarrier by a phase quantityφmIs the common phase error caused by the laser linewidth;
the expression of the estimated value of the public phase error obtained by using the conjugate pilot frequency sequence designed by the transmitting end is as follows:
wherein arg (·) represents the phase of the pilot sequence after multiplication,is the common phase error value estimated by the pilot frequency sequence;
then multiplying the signal sub-carrier of the coherent optical OFDM communication systemThereby removing the effect of laser phase noise.
Step 3, estimating IQ amplitude and phase imbalance factors of the transmitting end at the receiving end by further adopting a frequency domain second-order estimation algorithm;
specifically, the process of estimating the IQ amplitude and phase imbalance factor of the transmitting end by using a frequency domain second order estimation algorithm comprises the following steps:
setting the pilot subcarrier signal expression of the transmitting end as follows:
p[k]＝ck·ejkπ/2,|k|＝0,1,2...,NP. (31)
p[k]expression representing the k sub-carrier, ckIs the amplitude of the kth strength pilot;
performing frequency conversion modulation on the pilot frequency subcarrier signal to obtain a signal expression of the transmitting end, wherein the signal expression is as follows:
PI(k)＝cos(2πf0t+kπ/2)，PQ(k)＝sin(2πf0t+kπ/2)；
if there is IQ imbalance at the transmitting end, the I/Q paths at the receiving end are in an ideal state and are not considered. The expression of the baseband electrical signal received after passing through the optical fiber channel according to the formula (22) is
Where the sum Δ φ is the amplitude and phase imbalance factor, H, respectively, of the transmit sidekIs the channel response transfer function, f0Representing the frequency, ω k, of the modulated optical carrier]Is the channel gaussian noise.
Then, the sum Δ φ is estimated by using the strength pilot signals, and the specific implementation process is as follows:
order toSubstituted formula (33), for rI[k]By the following transformation, can be obtained
And after channel equalization, extracting an IQ imbalance factor of a transmitting terminal by adopting a frequency domain second moment estimation algorithm. The phase difference between adjacent pilots is pi/2, and the following expected relational expression can be obtained
In pilot design process ckAnd ck+1Using the received pilot signal, the calculated average value is substituted into equations (35) and (36) to obtain:
whereinThe IQ amplitude and phase imbalance factors can be solved by substituting the values of A and B into equation (37)
c is a known constant, NPFor the number of pilot frequency sub-carriers, I and Q represent two paths of signals at the transmitting end of the coherent optical OFDM communication system.
And step 4, further eliminating system performance deterioration caused by IQ mismatching of the transmitting end so as to improve the signal-to-noise ratio of the received signal.
In step 4, the process of eliminating system performance degradation caused by IQ mismatch at the transmitting end specifically includes:
the method assumes that an I path and a Q path of a coherent optical OFDM communication system transmitting end signal are S respectivelyIAnd SQAnd if the I/Q two paths of amplitude and phase imbalance and delta phi of the transmitting end exist, the signal expression of the receiving end is obtained as follows:
the final compensated signal expression is
Wherein,
in summary, the method provided by the embodiment of the present invention can solve the influence of the laser phase noise on signal demodulation in the coherent light OFDM system, estimate and compensate the IQ imbalance factor at the transmitting end, improve the performance of the transmission system, have low computational complexity, and can be easily implemented on a hardware platform.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (5)

1. A method for cascade compensation in a coherent optical OFDM communication system, the method comprising:
step 1, designing a pilot frequency subcarrier distribution scheme at a transmitting end of a coherent light OFDM communication system;
step 2, compensating the laser phase noise of the transmitting end by adopting a phase conjugate pilot frequency auxiliary method at the receiving end of the coherent light OFDM communication system;
step 3, estimating IQ amplitude and phase imbalance factors of the transmitting end at the receiving end by further adopting a frequency domain second-order estimation algorithm;
and step 4, further eliminating system performance deterioration caused by IQ mismatching of the transmitting end so as to improve the signal-to-noise ratio of the received signal.
2. The method of cascade compensation in the coherent optical OFDM communication system according to claim 1, wherein in the step 1:
the designed pilot subcarrier allocation scheme comprises: local subcarrier allocation and interleaved subcarrier allocation.
3. The method of cascade compensation in the coherent optical OFDM communication system according to claim 1, wherein in the step 2, the process of compensating the laser phase noise at the transmitting end by using the phase conjugate pilot aided method specifically comprises:
multiplying each pilot subcarrier by a phase quantityφmIs the common phase error caused by the laser linewidth;
the expression of the estimated value of the public phase error obtained by using the conjugate pilot frequency sequence designed by the transmitting end is as follows:
φ m ^ = arg ( Σ k = 1 N P p m , k · p m , - k ) 2 N P
wherein arg (·) represents the phase of the pilot sequence after multiplication,is the common phase error value estimated by the pilot frequency sequence;
then multiplying the signal sub-carrier of the coherent optical OFDM communication systemThereby removing the effect of laser phase noise.
4. The method of cascade compensation in the coherent optical OFDM communication system according to claim 1, wherein in the step 3, the IQ amplitude and phase imbalance factor expression of the estimated transmitting end is:
ϵ = A + B - c 2 c Δ φ = ± a r c t a n A - c 2 B
wherein, and Δ φ respectively represent IQ amplitude and phase imbalance factors of the transmitting end;
A = Σ k = 1 2 N P r I 2 [ k ] / N P ;
B = Σ k = 1 2 N P r Q 2 [ k ] / N P ;
c is a known constant, NPBeing pilot sub-carriersThe number, I and Q, represents two paths of signals at the transmitting end of the coherent light OFDM communication system.
5. The method of claim 4, wherein in the step 4, the procedure of eliminating system performance degradation caused by IQ mismatch at the transmitting end specifically comprises:
the method assumes that an I path and a Q path of a coherent optical OFDM communication system transmitting end signal are S respectivelyIAnd SQAnd if the I/Q two paths of amplitude and phase imbalance and delta phi of the transmitting end exist, the signal expression of the receiving end is obtained as follows:
r I r Q = 1 - ϵ s i n Δ φ 0 ϵ cos Δ φ S I S Q - - - ( 39 )
the final compensated signal expression is
r I _ c o m . r Q _ c o m . = f [ ϵ , Δ φ ] r I r Q - - - ( 40 )
Wherein,
CN201710032907.XA 2017-01-16 2017-01-16 Cascade compensation method in coherent light OFDM communication system Active CN106850497B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201710032907.XA CN106850497B (en) 2017-01-16 2017-01-16 Cascade compensation method in coherent light OFDM communication system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201710032907.XA CN106850497B (en) 2017-01-16 2017-01-16 Cascade compensation method in coherent light OFDM communication system

Publications (2)

Publication Number Publication Date
CN106850497A true CN106850497A (en) 2017-06-13
CN106850497B CN106850497B (en) 2020-05-15

Family

ID=59124582

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201710032907.XA Active CN106850497B (en) 2017-01-16 2017-01-16 Cascade compensation method in coherent light OFDM communication system

Country Status (1)

Country Link
CN (1) CN106850497B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108718217A (en) * 2018-03-16 2018-10-30 华北电力大学扬中智能电气研究中心 A kind of compensation method and device based on coherent optical communication system
CN109728856A (en) * 2017-10-27 2019-05-07 富士通株式会社 The unbalanced estimation device of optical sender IQ, compensation device and electronic equipment
CN112769497A (en) * 2021-02-23 2021-05-07 苏州大学 Method for carrying out nonlinear compensation on high-capacity high-order QAM coherent light
CN114124640A (en) * 2020-08-31 2022-03-01 中兴通讯股份有限公司 Signal compensation processing method and device

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103401829A (en) * 2013-06-26 2013-11-20 吉林大学 IQ imbalance compensation method for coherent-light orthogonal frequency division multiplexing (OFDM) communication system
CN103746947A (en) * 2014-01-07 2014-04-23 电子科技大学 Phase noise estimation method
CN104519006A (en) * 2014-12-25 2015-04-15 北京邮电大学 OFDM system phase noise elimination method based on orthogonal polarization transmission
US9270381B2 (en) * 2010-12-17 2016-02-23 Electronics And Telecommunications Research Institute Method and apparatus for transmitting and receiving coherent optical OFDM

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9270381B2 (en) * 2010-12-17 2016-02-23 Electronics And Telecommunications Research Institute Method and apparatus for transmitting and receiving coherent optical OFDM
CN103401829A (en) * 2013-06-26 2013-11-20 吉林大学 IQ imbalance compensation method for coherent-light orthogonal frequency division multiplexing (OFDM) communication system
CN103746947A (en) * 2014-01-07 2014-04-23 电子科技大学 Phase noise estimation method
CN104519006A (en) * 2014-12-25 2015-04-15 北京邮电大学 OFDM system phase noise elimination method based on orthogonal polarization transmission

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
徐湘艺，朱江: "OFDM中联合IQ不平衡和相位噪声估计补偿新算法", 《通信技术》 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109728856A (en) * 2017-10-27 2019-05-07 富士通株式会社 The unbalanced estimation device of optical sender IQ, compensation device and electronic equipment
CN109728856B (en) * 2017-10-27 2021-12-31 富士通株式会社 Estimation device and compensation device for IQ imbalance of optical transmitter and electronic equipment
CN108718217A (en) * 2018-03-16 2018-10-30 华北电力大学扬中智能电气研究中心 A kind of compensation method and device based on coherent optical communication system
CN114124640A (en) * 2020-08-31 2022-03-01 中兴通讯股份有限公司 Signal compensation processing method and device
CN112769497A (en) * 2021-02-23 2021-05-07 苏州大学 Method for carrying out nonlinear compensation on high-capacity high-order QAM coherent light
CN112769497B (en) * 2021-02-23 2022-02-22 苏州大学 Method for carrying out nonlinear compensation on high-capacity high-order QAM coherent light

Also Published As

Publication number Publication date
CN106850497B (en) 2020-05-15

Similar Documents

Publication Publication Date Title
JP6104948B2 (en) System and method for blind equalization and carrier phase recovery in quadrature amplitude modulation systems
Liang et al. Transceiver imbalances compensation and monitoring by receiver DSP
CA3047882C (en) Optical transmission characteristic estimation method, optical transmission characteristic compensation method, optical transmission characteristic estimation system and optical transmission characteristic compensation system
Leven et al. Real-time implementation of digital signal processing for coherent optical digital communication systems
CN106850497B (en) Cascade compensation method in coherent light OFDM communication system
US11218224B2 (en) DSP-free coherent receiver
US8855501B2 (en) Method for carrier frequency recovery and optical intradyne coherent receiver
US8306438B2 (en) Coherent optical receiver systems and methods
CN108566250B (en) Modulation and demodulation method and system based on carrier quadrature bias single sideband signal
CN105187345A (en) Non-iterative blind phase noise compensation method suitable for CO-OFDM system
US11277207B1 (en) Apparatus and method for in-phase and quadrature skew calibration in a coherent transceiver
Fan et al. Transceiver IQ imperfection monitor by digital signal processing in coherent receiver
JP7009890B2 (en) Bias drift compensator, received signal restoration device and receiver
Li et al. A joint recovery scheme for carrier frequency offset and carrier phase noise using extended Kalman filter
Lagha et al. Blind Joint Polarization Demultiplexing and IQ Imbalance Compensation for $ M $-QAM Coherent Optical Communications
Yoshida et al. Simultaneous monitoring of frequency-dependent IQ imbalances in a dual-polarization IQ modulator by using a single photodetector: A phase retrieval approach
CN109728856B (en) Estimation device and compensation device for IQ imbalance of optical transmitter and electronic equipment
US8718481B2 (en) Method and device for phase recovery and communication system comprising such device
US9106326B2 (en) Method for determining the imperfections of a transmit pathway and of a receive pathway of an apparatus, and associated radio apparatus
WO2023061213A1 (en) Optical signal skew extraction method and apparatus, electronic device, and storage medium
Lin et al. Pilot-aided low-complexity CFO and I/Q imbalance compensation for OFDM systems
EP2502365B1 (en) Signal processing apparatus, transmitter, receiver and method
Puntsri A Very Simple Algorithm of Sequential IQ Imbalance and Carrier Frequency Offset Compensation in Coherent Optical OFDM
Yang et al. Fiber nonlinearity and tight filtering impairments mitigation of DP-16QAM Nyquist-WDM systems using multiplier-free MAP detection
US20240187107A1 (en) Frequency offset estimation apparatus, receiving apparatus, frequency offset estimation method and program

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant