CN110011734A - CPE compensation method in CO-OFDM system based on pilot tone and two-dimensional projection's histogram - Google Patents
CPE compensation method in CO-OFDM system based on pilot tone and two-dimensional projection's histogram Download PDFInfo
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- 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
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Abstract
The present invention proposes the CPE compensation method in a kind of CO-OFDM system based on pilot tone and two-dimensional projection's histogram, the corresponding phase noise value of pilot tone is obtained as pilot tone using less several subcarriers first, the substantially value range of each OFDM symbol CPE phase noise is averagely obtained to it, and does preliminary phase noise compensation on the corresponding planisphere of each OFDM symbol.Then, preliminary compensated planisphere is projected respectively in in-phase component and quadrature component, it averages to obtain finer phase noise estimated value to the phase noise value that projection histogram algorithm obtains is done in same phase and orthogonal two dimensions, and obtains final CPE phase noise compensation value in conjunction with initial compensation value.The present invention solves the problems, such as the spectrum efficiency problems of CPE phase noise compensation and traditional pilot auxiliary CPE compensation method in CO-OFDM system with the decision error of tradition CPE blind estimating method and using pi/2 as the phase deviation problem in period.
Description
Technical field
The present invention relates to optical transport technology fields, and in particular to one kind is used for coherent light ofdm system
(Coherent Optical Orthogonal Frequency Division Multiplexing, CO-OFDM) based on leading
Frequently (Pilots-aided, PA) and two-dimensional projection's histogram (2-dimensional Projection Histogram, 2PH)
Phase noise compensation method.
Background technique
The advantages of coherent light orthogonal frequency division multiplexing (CO-OFDM) system combines coherent light communication and OFDM, resisting chromatic dispersion
Ability is strong, receiver sensitivity and spectrum efficiency are high.Phase noise is the main damage of CO-OFDM system, is mostly come from
The line width of laser is caused by the phase of transmitting terminal and receiving end mismatch.Firstly, OFDM is a kind of multi-carrier modulation technology,
Compared with single carrier modulation technique, symbol period is larger, more sensitive to phase noise, and phase noise can destroy between subcarrier
Orthogonality, cause common phase error (Common Phase Error, CPE) and inter-sub-carrier interference (Inter-carrier
Interference, ICI) to deteriorate system performance, and laser phase noise can be converted to after the transmission of dispersive optical fiber kind
Intensity noise restricts maximum transmission distance.Secondly, the modulation system of CO-OFDM is usually M-ary Quadrature Amplitude modulation
(Multiple Quadrature Amplitude Modulation, MQAM), and MQAM as a kind of high order modulation easily by
To the influence of phase noise.Finally, the coherent detection technology in CO-OFDM system needs accurate tracking transmission signal and local vibration
The phase and frequency between device output is swung, and laser phase noise can interfere it.
It is found through being retrieved to existing literature, phase noise reduction algorithm is broadly divided into CPE backoff algorithm and ICI compensation at present
Algorithm.In CO-OFDM system, CPE phase noise makes each subcarrier phase noise having the same in frequency-domain OFDM symbol
Component shows as the integral-rotation of constellation point on planisphere；ICI phase noise is the random phase rotation that different sub-carrier has
Turn, the rotation of constellation point is shown as on planisphere.When laser linewidth is smaller, ICI can be equivalent to the Gauss of zero-mean
Noise processed only need to estimate that CPE can have preferable compensation effect；When laser linewidth is larger, then need using ICI as dimension
Process of receiving processing.
CPE backoff algorithm includes data aided algorithm and blind backoff algorithm.Such as Xingwen Yi et al. is delivered
The pilot aided (Pilot-Aided, PA) proposed in " Phase Estimation for Coherent Optical OFDM "
Algorithm, main thought are to estimate CPE by calculating the phase noise mean value of all pilot tones in an OFDM symbol.PA algorithm
Using wide and accuracy rate, higher but additional pilot-frequency expense reduces the availability of frequency spectrum.Mohammad E.Mousa-
" the Zero-overhead phase noise compensation via decision- that Pasandi et al. is delivered
Directed phase equalizer for coherent optical OFDM " in propose decision-directed (Decision-
Directed, DD) algorithm, main thought is to reevaluate and compensate phase noise using the initial judgement of current sign,
And balance parameters are updated one by one, but the algorithm increases the time complexity height of system.In addition, what Junjie Ma et al. was delivered
《Projection Histogram Assisted Common Phase Estimation Algorithm in Coherent
Optical OFDM System " in propose it is a kind of based on projection histogram (Projection Histogram Assisted,
PH the busy backoff algorithm of CPE), main thought is the image regarded M-QAM planisphere as in two-dimensional surface, makes CO-OFDM system
Phase estimation problem in system is converted to the problem of seeking image inclination angle, can be made by determining one to the rotation of constellation point coordinate
There is log in projection histogram2The angle of M peak-peak is compensated as optimal CPE value.DD algorithm and PH do not need any
Pilot tone, spectrum efficiency are high, but it is sufficiently small to be only applicable to CPE, is not sufficient to the case where leading to decision error.
Summary of the invention
For the defects in the prior art, the present invention provides a kind of CO- based on pilot tone and two-dimensional projection's histogram
CPE compensation method in ofdm system, includes the following steps:
Step 1: the OFDM digital signal with pilot sub-carrier and training sequence is converted to optical signal by Electro-optical Modulation
It is transmitted through optical link, electric signal is converted to for optical signal is received using coherent optical detection in receiving end.
Step 2: when calculating the channel transfer function estimated value of each OFDM subcarrier using training sequence, and be based on
The average channel equalization in domain.
Step 3: each OFDM symbol being calculated to the ofdm signal after channel equalization and is made an uproar in the phase of pilot subcarrier positions
Sound value is simultaneously averaged, as the initial CPE phase noise estimated value of each OFDM symbol.
Step 4: the planisphere of each OFDM symbol compensated in step 3 being mapped to two-dimensional digital image and is utilized
Radon transformation carries out coordinate rotation, is obtained according to projection histogram of the image in same phase and orthogonal both direction finer
CPE phase noise estimated value.
Step 5: in conjunction with finer common phase noise in the initial CPE phase noise estimated value and step 4 in step 3
Estimated value obtains the phase noise estimated value of final each OFDM symbol and compensates.
Preferably, in the step 1, the infix form of pilot sub-carrier is Comb Pilot, and carries the son of pilot data
Number of carrier wave is a small amount of.
Preferably, in the step 3, rough phase noise is carried out first with a small amount of pilot sub-carrier and is estimated, and
This estimated value is used for the first compensation of phase noise, is week with pi/2 when solving to do CPE blind estimate with two-dimensional projection's histogram
The offset issue of phase.
Preferably, in the step 4, for the ofdm signal of M-QAM modulation, by same phase and orthogonal both direction
Projection histogram will make respectively with the appearance log mutually with the projection histogram of orthogonal direction2M most apparent Gaussian Profiles
When two common phase noise estimated values average value as finer CPE phase noise estimated value.
Preferably, in the step 5, final relevant optical OFDM system common phase noise estimated value is by step 2
Finer estimated value two parts composition in initial estimate and step 4.Initial estimate is used for CPE estimated value in CPE reality
The deviation of actual value controls in [- π/4, π/4] range, and finer estimated value is for further adjusting CPE estimated value to CPE
Near actual value.
Specific step is as follows for two-dimensional projection's histogram CPE blind estimate:
1) it, is carried out the rough common phase noise estimated value obtained using a small amount of pilot tone as the initial compensation value of CPE
Compensation, the rotation angular deviation of planisphere and ideal constellation after guaranteeing initial compensation is in [- π/4, π/4] range.
2) it, is used in an OFDM symbol with a fixed step size value as CPE test value in [- π/4, π/4] range
Above-mentioned all test values are compensated as offset, and compensated planisphere are sampled into two-dimensional digital image, then pass through
Radon converts to obtain these two-dimensional digital images in the projection histogram of same phase and orthogonal two dimensions.
3), picking out can make log occur with the projection histogram mutually or in orthogonal two dimensions in step 22M most obvious
Gaussian Profile spike, and in log2Test value when the sum of pixel quantity in the certain field of M projection centre is maximum,
And the two test values are averaged as CPE estimated value finer in an OFDM symbol.
4), for each received OFDM symbol, repeat the above steps 1, step 2, step 3 after channel equalization,
Obtain the optimal finer CPE estimated value of each OFDM.
Preferably, in the step 1), used pilot number be it is a small amount of, purposes is the initial benefit as CPE
Value is repaid, existing decision error when the CPE blind estimate based on two-dimensional projection's histogram is avoided and is asked by the deviation in period of pi/2
Topic.
Preferably, in the step 2), for each test phase, the deflection angle being converted on planisphere,
And using Radon transformation and the coordinate transformation relation between polar coordinate system and rectangular coordinate system, two-dimensional digital image is completed
Rotation.Relative to directly to digital picture do rotation process or directly by each test phase substitute into it is balanced after reception signal
For compensating again, reduce computation complexity.
Preferably, the step 3), due in some cases, receiving end I, Q as caused by when channel equalization is not ideal enough
It mismatches, not being so as to cause planisphere is an approximating square, therefore, by the optimal survey in same phase and orthogonal both direction
Examination value averages to compromise.
CPE compensation method of the invention is two-dimensional projection's histogramming algorithm based on pilot tone.The CPE of traditional pilot aided
Backoff algorithm accuracy is high, and use scope is wide, but needs additional pilot-frequency expense, therefore spectrum efficiency is low.The blind benefit of traditional CPE
It repays algorithm and does not need any pilot tone, spectrum efficiency is high, but receives the prior information of signal due to lacking, for the benefit of phase noise
It repays and needs to carry out by decision-feedback, therefore, in the case of phase noise is slightly larger, will lead to mistake in judgment, to produce
Raw error accumulation.The present invention sufficiently combines the advantage of two kinds of CPE compensation methodes, will receive signal first with a small amount of pilot tone
Within the scope of phase noise compensation to blind estimate algorithm acceptable, the blind benefit based on two-dimensional projection's histogram is then recycled
It repays algorithm and further compensates it.
Compared with prior art, the present invention have it is following the utility model has the advantages that
1, the present invention reaches same BER and EVM performance when institute compared with the CPE compensation method of traditional pilot aided
The pilot number needed substantially reduces, and spectrum efficiency is higher.
2, for the present invention compared with traditional blind compensation method of the CPE based on projection histogram, use scope is wider, solves
Decision error of the blind backoff algorithm of CPE when phase noise is larger with using pi/2 as the phase deviation problem in period.
The present invention is used for the CPE compensation method based on pilot tone and projection histogram of CO-OFDM system, first using less
Several subcarriers obtain the corresponding phase noise value of pilot tone as pilot tone, each OFDM symbol CPE phase is averagely obtained to it
The substantially value range of noise, and preliminary phase noise compensation is done on the corresponding planisphere of each OFDM symbol.Then, right
Preliminary compensated planisphere projects respectively in in-phase component and quadrature component, straight to projection is done in same phase and orthogonal two dimensions
The phase noise value that square nomography obtains averages to obtain finer phase noise estimated value, and initial compensation is combined to be worth
To final CPE phase noise compensation value.The present invention solves the problems, such as the CPE phase noise compensation in CO-OFDM system, and
Traditional pilot assists the spectrum efficiency problems of CPE compensation method and the decision error of tradition CPE blind estimating method and is week with pi/2
The phase deviation problem of phase.
Detailed description of the invention
By reading referring to the following drawings, by comparing tradition CPE compensation technique, other feature of the invention, purpose and
Advantage will become more apparent upon:
Fig. 1 is the CO-OFDM system structure diagram using the transformation of direct up/down.
Fig. 2 is two-dimensional projection's schematic diagram of 16QAM planisphere.
Fig. 3 is the CPE backoff algorithm flow chart based on pilot tone and two-dimensional projection's histogram.
The BER and received optical power relational graph of three kinds of algorithms when Fig. 4 is different pilot tone accountings, in figure: horizontal axis is to receive light
Power, the longitudinal axis are BER values, and wherein BER performance comparison has respectively: the blind backoff algorithm of CPE and pilot tone accounting difference based on PH
CPE backoff algorithm when being 1.25%, 2.5%, 5%, 10% based on PA and proposed by the present invention it is based on pilot tone and two-dimensional projection
The CPE backoff algorithm of histogram.
Specific embodiment
The present invention is described in detail combined with specific embodiments below.Following embodiment will be helpful to the technology of this field
Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill of this field
For personnel, without departing from the inventive concept of the premise, several changes and improvements can also be made.These belong to the present invention
Protection scope.For this purpose, the present invention is tested to verify the effect of CPE compensation using 16QAM signal.
The present invention is used for the CPE compensation method based on pilot tone and two-dimensional projection's histogram of CO-OFDM system, and process is as schemed
Shown in 1, in transmitting terminal, high code rate symbol stream is converted into multiple low by serial pseudo-random signal to be transmitted by serial/parallel conversion
Code rate symbol stream, and it is inserted into the leading instruction of initial estimation and part that a small amount of subcarrier is used for phase noise as pilot sub-carrier
Practice sequence and is used for channel estimation.Then, information corresponding with subcarrier is mapped in OFDM symbol by 16QAM modulation to accord with
Number, then OFDM symbol is transformed into from frequency domain by time domain by inverse Fourier transform, cyclic prefix is inserted into prevent due to channel color
Intersymbol interference caused by dissipating.Be then passed through it is parallel/serial be converted into live signal waveform, the real and imaginary parts of signal pass through I/Q
Be modulated to mutually and quadrature component is sent into fibre channel transmission, and receiving end using relevant detection to same phase and quadrature component into
Reception signal after the isolated transmission of row.To reception signal serial/parallel conversion, removal cyclic prefix and Fourier transformation
Afterwards, the frequency-region signal of received OFDM symbol is obtained.The planisphere of rough compensated each ofdm signal is mapped to two again
Dimension word image, and it is calculated in the projection histogram of same phase and orthogonal direction, it obtains the finer CPE of each OFDM symbol and estimates
Evaluation simultaneously compensates.Specifically includes the following steps:
Step 1: the OFDM frequency-region signal through 16QAM modulation with training sequence and a small amount of pilot sub-carrier is by Fu
Leaf inverse transformation is simultaneously inserted into after cyclic prefix and is converted to real-time time-domain signal, and real and imaginary parts are same phase by I/Q modulation conversion
And quadrature component, it is sent into fibre channel transmission.
Step 2: receiving end simultaneously removes cyclic prefix with phase and quadrature component, serial/parallel conversion using coherent optical detection separation
Afterwards, received OFDM time-domain signal is obtained using Fourier transformation.
Step 3: carrying out time domain average channel equalization using leading training sequence, obtained using a small amount of pilot sub-carrier each
The common phase noise initial estimate of OFDM symbol simultaneously carries out initial compensation.
Step 4: for the OFDM symbol after each initial compensation, carrying out the CPE phase based on two-dimensional projection's histogram and make an uproar
Sound is estimated and is compensated.
Step 5: being combined the CPE phase noise initial estimate and utilize two-dimensional projection's histogram that a small amount of pilot tone obtains
The finer CPE phase noise estimated value that figure obtains is as final phase noise estimated value.
Further the term in step is explained:
1, the phase noise being concerned in optical OFDM system consists of two parts, between common phase noise (CPE) and subcarrier
It interferes (ICI).
Assuming that receiving end perfect synchronization and be not present spectrum offset, then the time-domain signal r before Fourier transformationi,kIt can be with
It indicates are as follows:
Wherein, subscript i and k represents k-th of subcarrier of i-th of OFDM symbol, si,kRepresent originally transmitted signal, hi,kIt is
The unit impulse response of system,It is previously mentioned laser phase noise, ωi,kIt is additive white Gaussian noise
(Additive White Gaussian Noise,AWGN).The presence of ISI is not considered, and the frequency-region signal after FFT is by following three
Part forms:
Wherein, first item is common phase noise, and Section 2 is inter-sub-carrier interference, and Section 3 is additive Gaussian white noise
Sound.The present invention is for estimating and compensating the common phase noise part in phase noise.
2, the estimation and compensation of CPE phase noise are used a pilot for
As known to 1, CPE phase noise makes each subcarrier phase noise having the same in frequency-domain OFDM symbol point
Amount, shows as the integral-rotation of constellation point, the CPE phase noise of i-th of OFDM symbol can indicate on planisphere are as follows:
The corresponding phase noise of p-th of pilot tone isIt indicates are as follows:
Tradition based on the CPE phase noise estimation method of pilot tone by the mean value of the phase noise of subcarrier where pilot tone come
CPE phase noise value is approached, can be indicated are as follows:
Compensated OFDM frequency-region signal estimated value table is used a pilot for be shown as:
Therefore, pilot number NpBigger, estimated result is more accurate, but the availability of frequency spectrum is also lower.
3, common phase noise estimation and compensation based on two-dimensional projection's histogram
Common phase noise compensation method based on two-dimensional projection's histogram is a kind of blind compensation method, and specific steps are such as
Under:
1), for a reception OFDM symbol, its planisphere is mapped to two-dimensional digital image.
2) it, is converted using Radon, obtains two projection histograms of the two-dimensional digital image in same phase and orthogonal direction.
3) it, takes test phase to rotate integrally planisphere with a fixed step size in [- π/4, π/4] range, and repeats
Step 1 and step 2, picking out two can make the projection histogram of two dimensions 4 apparent Gaussian Profiles occur respectively
Spike, and test value when the sum of pixel quantity in 4 certain fields of projection centre is maximum, and by the two test values
It averages, the optimal CPE phase noise compensation value as the OFDM symbol.
4) it, for the OFDM symbol that each is received, repeats the above steps.
Therefore, the common phase noise compensation method based on two-dimensional projection's histogram does not need any pilot tone, but works as CPE phase
Position noise is larger so that planisphere entirety angular deflection caused by CPE has exceeded [- π/4, π/4], if at this time still only with
CPE phase noise compensation algorithm based on two-dimensional projection's histogram, since compensation range is in [- π/4, π/4] range, therefore
Although the result finally compensated can make the planisphere for receiving signal that the distribution of 16 constellation points be presented, part is by phase noise
The planisphere for the OFDM symbol being affected and its ideal constellation can exist using pi/2 as the angular deviation in period, cause final
All data decision mistakes in these OFDM symbols.
CPE compensation method based on pilot tone and two-dimensional projection's histogram of the invention includes two parts: based on pilot tone
Initial compensation and finer compensation based on two-dimensional projection's histogram.
Referred to based on the initial compensation of pilot tone using a small amount of pilot tone guarantee the ofdm signal planisphere after initial compensation with
Its ideal constellation angular deviation is in [- π/4, π/4] range, in order to carry out based on the finer of two-dimensional projection's histogram
CPE compensation.
[- π/4, π/4] are divided into M parts as test phase, the test phase of i-th of OFDM symbol firstIt can be with
It indicates are as follows:
Then compensated signal is obtained using each test phase as compensation phase
As shown in Figures 2 and 3, the compensated ofdm signal of test phase is used for each, by the constellation in its planisphere
Respectively to I axis and Q axial projection, the projection histogram of postrotational two dimensions of planisphere can be converted by Radon and be indicated point:
When receiving signal there is no when CPE phase noise, the planisphere for receiving signal is not rotated integrally, at this time constellation point
It is in Gaussian Profile near 16 ideal constellation points, by it respectively to I axis, Q axial projection, then projection histogram also shows as 4
Gaussian Profile；When receiving signal there are when phase noise, CPE leads to the integral-rotation for receiving the planisphere of signal, projects histogram
4 Gaussian Profile ranges of figure are superimposed, and are caused without apparent spike.ForCompensated two-dimensional projection's histogram, point
Not Ji Suan I axis, Q axis 4 projection centre contiguous ranges (in radius of neighbourhood a) constellation point sumAnd by the number of constellation points of I axis, Q axial projection immediate vicinity
Summation obtainsWithIt is shown below:
It willWhen being maximizedValueWithWhen being maximizedValueIt asks
It is average, and the CPE tentatively compensated is combined to be worth according to a preliminary estimateObtain more accurate CPE phase noise estimation
Simulating, verifying is carried out based on the CPE backoff algorithm of pilot tone and two-dimensional projection's histogram to proposed by the present invention.OFDM
Signal uses rectangular 16QAM modulation format, and FFT/IFFT is dimensioned to 128, sample rate 10GSa/s.In the wavelength of laser
The heart is 1550nm, and best transmission power is set as 10dBm, and laser linewidth is set as 50kHZ.In transmitting terminal, respectively in frequency band
10 protection subcarriers are distributed in two sides, set data subcarrier for 80 subcarriers, and by 0 distribution in remaining subcarrier
On, by base band and high-frequency separating.After the ifft, the CP that length is 16 is inserted into each OFDM symbol.In receiving end,
Signal is received to mix in 90 ° of optical mixers with local laser signal and be divided into 4 outputs.Then, 4 outputs respectively enter
A pair of of BPD, to obtain the I and Q component of CO-OFDM signal.500 OFDM symbols are in the standard single mode light that loss is 0.2dB/km
50km is transmitted in fine (Standard SMF, SSMF), the gain of EDFA is 10dB.
The BER and received optical power relational graph of three kinds of CPE phase noise compensation algorithms, right when Fig. 4 is different pilot tone accountings
In the CPE compensation method of traditional pilot aided (PA), with the increase of pilot tone accounting, the mean value of phase noise will be more at pilot tone
Carry out the phase noise average value in an OFDM symbol, to reach the estimation and compensation of CPE.Also, with pilot tone
The increase of accounting, BER performance also enhance.For be based on projection histogram (PH) the blind compensation method of CPE, due to above-mentioned π/
2 period tripping problems, BER performance allow of no optimist compared to other two kinds of CPE compensation methodes.The PA-2PH proposed is calculated
Method, with the increase of pilot tone accounting, BER performance is almost stable, and when pilot tone accounting only has 1.25%, BER performance is still
So reach 10% PA compensation method better than pilot tone accounting.Therefore, the PH-2PH algorithm proposed is relative to traditional PA algorithm
Higher BER performance can be reached using less pilot-frequency expense.
In conclusion the present invention has only used a small amount of pilot tone, pilot-frequency expense is reduced to a certain extent, enhances frequency
Compose utilization rate, solve the problems, such as the blind backoff algorithm of the CPE based on two-dimensional projection's histogram using pi/2 as the angular deviation in period with sentence
Certainly error problem, and reached higher accuracy.It thus can be compared in the CPE backoff algorithm of two-dimensional projection's histogram based on pilot tone
It is applied in CO-OFDM system well, and meets low pilot-frequency expense.
Specific embodiments of the present invention are described above.It is to be appreciated that the invention is not limited to above-mentioned
Particular implementation, those skilled in the art can make a variety of changes or modify within the scope of the claims, this not shadow
Ring substantive content of the invention.In the absence of conflict, the feature in embodiments herein and embodiment can any phase
Mutually combination.
Claims (6)
1. the CPE compensation method in the CO-OFDM system based on pilot tone and two-dimensional projection's histogram, which is characterized in that including such as
Lower step:
Step 1: the OFDM digital signal with pilot sub-carrier and training sequence is converted to optical signal transmission by Electro-optical Modulation,
Electric signal is converted to for optical signal is received using coherent optical detection in receiving end；
Step 2: calculating the channel transfer function estimated value of each OFDM subcarrier using training sequence, and carry out channel equalization；
Step 3: each OFDM symbol is calculated in the phase noise value of pilot subcarrier positions to the ofdm signal after channel equalization
And average, the initial CPE estimated value as each OFDM symbol；
Step 4: the planisphere of each OFDM symbol compensated in step 2 being mapped to two-dimensional digital image and carries out image rotation
Turn, finer CPE estimated value is obtained according to projection histogram of the image in same phase and orthogonal both direction；
Step 5: in conjunction with finer CPE estimated value in the initial CPE estimated value and step 4 in step 3, obtaining final each
The CPE estimated value of OFDM symbol simultaneously compensates.
2. compensation method according to claim 1, which is characterized in that in step 1, the infix form of pilot sub-carrier is comb
Shape pilot tone, and the number of subcarriers for carrying pilot data is a small amount of.
3. compensation method according to claim 1, which is characterized in that in step 2, fiber channel is considered as slow fading letter
Road is each determined from the channel transfer function of subcarrier by training sequence.
4. compensation method according to claim 1, which is characterized in that in step 3, first with a small amount of pilot sub-carrier
Initial CPE estimation is carried out, and initial CPE estimated value is used for the first compensation of phase noise.
5. compensation method according to claim 1, which is characterized in that in step 4, by same phase and orthogonal both direction
Projection histogram, will make respectively with mutually and orthogonal direction projection histogram occur 4 most obvious spikes when two CPE
The average value of estimated value is as finer CPE estimated value.
6. compensation method according to claim 1, which is characterized in that in step 5, final relevant optical OFDM system is public
Phase noise estimated value is made of finer CPE estimated value two parts in the initial CPE estimated value and step 4 in step 2.
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| CN111355679A (en) * | 2020-03-18 | 2020-06-30 | 苏州华兴源创科技股份有限公司 | Phase angle calculation method, device and system for digital communication |
| CN111447159A (en) * | 2020-04-02 | 2020-07-24 | 宁波艾欧迪互联科技有限公司 | Channel estimation method |
| CN111884727A (en) * | 2020-07-15 | 2020-11-03 | 杭州电子科技大学 | High-speed photon digital-to-analog conversion method and system based on digital mapping |
| CN113300779A (en) * | 2021-04-26 | 2021-08-24 | 浙江工业大学 | Pilot-assisted CO-FBMC/OQAM system phase noise compensation method |
| CN114039829A (en) * | 2021-11-09 | 2022-02-11 | 北京邮电大学 | Phase recovery method and system based on pilot frequency assistance |
| CN114338334A (en) * | 2021-11-22 | 2022-04-12 | 北京理工大学 | Phase noise estimation and compensation method based on pseudo code pilot frequency |
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