CN108881087A - One kind being used for the received frequency deviation estimating method of K-K - Google Patents
One kind being used for the received frequency deviation estimating method of K-K Download PDFInfo
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- CN108881087A CN108881087A CN201811068902.3A CN201811068902A CN108881087A CN 108881087 A CN108881087 A CN 108881087A CN 201811068902 A CN201811068902 A CN 201811068902A CN 108881087 A CN108881087 A CN 108881087A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
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- 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
- H04B10/6164—Estimation or correction of the frequency offset between the received optical signal and the optical local oscillator
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- 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
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/0014—Carrier regulation
- H04L2027/0024—Carrier regulation at the receiver end
- H04L2027/0026—Correction of carrier offset
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Abstract
The present invention provides one kind to be used for the received frequency deviation estimating method of K-K, which is characterized in that includes the following steps：S1, signal baud rate B is determined；S2, it is received using K-K and restores signal whole audience information and carry out offset estimation and restore.The beneficial effects of the invention are as follows：It is received using K-K and realizes that frequency deviation is restored, on the one hand reduce the requirement of local oscillator laser, reduced into cost, on the other hand improve signal quality.
Description
Technical field
The present invention relates to optic communication parameter Estimations, more particularly to one kind to be used for the received frequency deviation estimating method of K-K.
Background technique
In recent years, explosive growth was presented in the information interaction amount of short-distance and medium-distance in data center, between data center etc., this
The rate of communication system is put forward new requirements；On the other hand, this kind of communication is also extremely sensitive to cost of implementation.For meet with
Upper requirement, the K-K proposed in the recent period (Kramers-Kronig) reception technique are one of very promising schemes.It can lead to
The whole audience information that the mode directly detected restores signal is crossed, therefore is suitable for IQ modulated signal, while some receptions can be used
End DSP algorithm compensates signal impairment.Relatively traditional direct detection scheme, greatly improves the availability of frequency spectrum and biography
Defeated distance.On the other hand, since K-K reception technique realizes that difficulty is low, in elastic optical network of new generation in terms of signal monitoring
In the presence of very big application potential.And in K-K reception system, estimation and the compensation of frequency shift (FS) are also a particularly important mould
Block and link.
Therefore, how to be received using K-K and realize that frequency deviation is restored, to realize the requirement for reducing local oscillator laser, meanwhile, it improves
Signal quality is those skilled in the art's technical problem urgently to be resolved.
Summary of the invention
In order to solve the problems in the prior art, the present invention provides one kind be used for the received frequency deviation estimating method of K-K, one
Aspect reduces the requirement of local oscillator laser, on the other hand improves signal quality.
The present invention provides one kind to be used for the received frequency deviation estimating method of K-K, which is characterized in that includes the following steps：
S1, signal baud rate B is determined；
S2, it is received using K-K and restores the whole audience information of transmission signal and carry out offset estimation and restore.
As a further improvement of the present invention, step S1 includes：Photoswitch is in close state, and local oscillator laser is not involved in
The partial information light field E of fiber transmission link is extracted in work by couplers(t), corresponding intensity letter is obtained after PD is detected
Cease Is(t), strength information Is(t) Fast Fourier Transform (FFT) is carried out after ADC acquisition quantization determine signal baud rate B.
As a further improvement of the present invention, step S2 includes following sub-step：
S21, signal optical electric field are restored；
S22, offset estimation and recovery.
As a further improvement of the present invention, step S21 includes：
After determining signal baud rate B, photoswitch is opened, local oscillator laser is started to work, it is assumed that the local oscillator light of addition can be with
Signal is set to meet minimum phase condition, the local oscillator light E of generationLOWith part signal light field Es(t) it closes beam and obtains light field E (t)=ELO+
Es(t), it is detected by PD, the electric signal of output is：
I (t)=[ELO+Es(t)]2 (1)
The electric signal I (t) of PD output quantifies the DSP under laggard line through ADC acquisition and handles；
The phase information φ that the strength information received is reverted to minimum phase signal E (t) is received first with K-KE
(t), and then the whole audience information for transmitting signal is acquiredAs following formula describes：
Wherein p.v. is Cauchy's principal value, and I (t ') is the I (t) in (1) formula；T and t ' is the time, and t is independent variable, and t ' is
Integration variable, i are imaginary units, receive to have obtained the whole audience information of transmission signal by K-K
As a further improvement of the present invention, step S22 includes：First to the whole audience information of transmission signalCarry out 4
Power operation then carries out Fast Fourier Transform (FFT) to it, finds the maximum spectrum component in Fourier spectrum, frequency deviation and maximum
Spectrum component is related, carries out offset estimation according to maximum spectrum component and restores.
The beneficial effects of the invention are as follows：Through the above scheme, it is received using K-K and realizes that frequency deviation is restored, on the one hand reduced
The requirement of local oscillator laser reduces into cost, on the other hand improves signal quality.
Detailed description of the invention
Fig. 1 is a kind of direct receipt signal frequency spectrum figure for the received frequency deviation estimating method of K-K of the present invention.
Fig. 2 is signal spectrum figure after a kind of removal phase information for the received frequency deviation estimating method of K-K of the present invention.
Fig. 3 is a kind of flow chart for the received frequency deviation estimating method of K-K of the present invention.
Specific embodiment
The invention will be further described for explanation and specific embodiment with reference to the accompanying drawing.
One kind being used for the received frequency deviation estimating method of K-K, is primarily adapted for use in and receives system in the K-K of receiving end addition local oscillator light
System in these cases, can use program realization as signal monitoring in signal reception and dynamic elasticity optical-fiber network
Frequency deviation is restored.On the one hand the requirement of local oscillator laser is reduced, while signal quality can be improved.
K-K (Kramers-Kronig) receives system, and to signal, there are two require：1) received optical signal is unilateral takes a message
Number；2) CSPR (local oscillator light and signal light power ratio, unit dB) is sufficiently large to meet minimum phase condition.To first item
Part, it is desirable that there are sufficiently large offset, which should be greater than the one of signal bandwidth for the frequency of local oscillator light and the frequency of signal carrier
Half；To second condition, it is desirable that local oscillation optical power is sufficiently large, it is however generally that, CSPR should be greater than 7dB.In the case where meeting conditions above,
It can use K-K and receive the phase information that the strength information that (also known as K-K algorithm) direct detection arrives restores signal.However, adding
When adding local oscillator light, the wavelength control of tunable laser is there are certain precision, and there may be certain drifts for local oscillator optical wavelength.
In addition, the defect that laser itself is also likely to be present, so that the local oscillator light frequency of actual loaded and given frequency exist centainly
Offset.These offsets finally transfer in signal after K-K algorithm, and the error performance received is caused to deteriorate.Therefore it needs
Frequency deviation recovery is carried out, different from traditional coherent reception frequency deviation, frequency deviation at this time is actual carrier, local oscillator light frequency difference and
The offset of the carrier wave, local oscillator light frequency difference known.In the present solution, the method using maximum spectrum component carries out frequency deviation recovery.
As shown in figure 3, a kind of be used for the received frequency deviation estimating method of K-K, implementation process can be divided into two stages：The
One stage determined signal baud rate B；Second stage is gone forward side by side line frequency using the whole audience information that K-K coherent reception restores transmission signal
Estimation and recovery partially.
First stage：
As shown in figure 3, photoswitch, for closed state, local oscillator laser is not involved in work, optical fiber is extracted by coupler
The partial information light field E of transmission links(t), corresponding strength information I is obtained after PD detects (photodetection)s(t), intensity is believed
Cease Is(t) Fast Fourier Transform (FFT) (FFT) is carried out after ADC (analog-digital converter) acquisition quantization determine signal baud rate B.Such as figure
Shown in 1, as long as extracting the spectrum component of diagram, that is, it can determine that signal wave spy leads B.Baud rate B will be extensive with K-K algorithm later
Complex signal phase information, as shown in formula (3).
Second stage：
1, signal optical electric field is restored
As shown in figure 3, opening photoswitch after determining signal baud rate, local oscillator laser is started to work, it is assumed that the sheet of addition
Vibration light can make signal meet minimum phase condition.The local oscillator light E of generationLOWith part signal light field Es(t) it closes beam and obtains light field E
(t)=ELO+Es(t), (photodetection) is detected by PD, the electric signal of output is：
I (t)=[ELO+Es(t)]2 (1)
The electric signal I (t) of PD output quantifies the DSP under laggard line through ADC (analog-digital converter) acquisition and handles.It is sharp first
Restore the phase information φ of minimum phase signal E (t) by the strength information received with K-K algorithmE(t), and then transmission is acquired
The whole audience information of signalSpecifically available following formula description：
Wherein p.v. is Cauchy's principal value, and I (t ') is the I (t) in (1) formula；T and t ' is the time, and t is independent variable, and t ' is
Integration variable, i are imaginary units.The whole audience information of transmission signal has been obtained by K-K algorithmDue to failing accurate determination
The offset of practical local oscillator light and carrier frequency, is only calculated using baud rate B as reference value, therefore actual offset and wave
There may be certain offsets by special rate B.Therefore need to carry out frequency deviation recovery, can using find maximum spectrum component method into
Row offset estimation and recovery.
2, offset estimation and recovery
As shown in figure 3, firstly, the whole audience information for transmitting signal restored to K-K4 power operations are carried out, it is then right
It carries out FFT transform, finds the maximum spectrum component in Fourier spectrum, frequency deviation is related to maximum spectrum component, can foundation
Maximum spectrum component carries out offset estimation and restores, as shown in Fig. 2, for frequency spectrum after 4 power operations, maximum spectrum intensity institute in figure
Corresponding frequency is frequency deviation.Frequency shift (FS) used in the calculating of K-K algorithm can be removed by this method and actual shifts are poor
The influence of value.
K-K reception technique is explained as follows：
K-K, that is, Kramers-Kronig, K-K reception technique be A.Mecozzi et al. in 2016 in document Kramers-
What is proposed in Kronig coherent receiver is a kind of by directly detecting recovery signal whole audience information (amplitude and phase)
Receiving side signal case, the program are based primarily upon Kramers-Kronig relationship.
It is provided by the invention a kind of for the received frequency deviation estimating method of K-K, it can be used for K-K and receive frequency deviation recovery, master
It will be suitable for receiving system in the K-K of receiving end addition local oscillator light, as believing in signal reception and dynamic elasticity optical-fiber network
Number monitoring, in these cases, can use the program realize frequency deviation restore.On the one hand the requirement of local oscillator laser is reduced,
Received signal quality can be improved simultaneously.
The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be said that
Specific implementation of the invention is only limited to these instructions.For those of ordinary skill in the art to which the present invention belongs, exist
Under the premise of not departing from present inventive concept, a number of simple deductions or replacements can also be made, all shall be regarded as belonging to of the invention
Protection scope.
Claims (5)
1. one kind is used for the received frequency deviation estimating method of K-K, which is characterized in that include the following steps：
S1, signal baud rate B is determined；
S2, it is received using K-K and restores the whole audience information of transmission signal and carry out offset estimation and restore.
2. according to claim 1 be used for the received frequency deviation estimating method of K-K, which is characterized in that step S1 includes：Light is opened
Pass is in close state, and local oscillator laser is not involved in work, and the partial information light field of fiber transmission link is extracted by coupler
Es(t), corresponding strength information I is obtained after PD is detecteds(t), strength information Is(t) quick Fu is carried out after ADC acquisition quantization
In leaf transformation determine signal baud rate B.
3. according to claim 2 be used for the received frequency deviation estimating method of K-K, which is characterized in that step S2 includes following
Sub-step：
S21, signal optical electric field are restored；
S22, offset estimation and recovery.
4. according to claim 3 be used for the received frequency deviation estimating method of K-K, which is characterized in that step S21 includes：
After determining signal baud rate B, photoswitch is opened, local oscillator laser is started to work, it is assumed that the local oscillator light of addition can make letter
Number meet minimum phase condition, the local oscillator light E of generationLOWith part signal light field Es(t) it closes beam and obtains light field E (t)=ELO+Es
(t), it is detected by PD, the electric signal of output is：
I (t)=[ELO+Es(t)]2 (1)
The electric signal I (t) of PD output quantifies the DSP under laggard line through ADC acquisition and handles；
The phase information φ that the strength information received is reverted to minimum phase signal E (t) is received first with K-KE(t), into
And acquire the whole audience information of transmission signalAs following formula describes：
Wherein p.v. is Cauchy's principal value, and I (t ') is the I (t) in (1) formula；T and t ' is the time, and t is independent variable, and t ' is integral
Variable, i are imaginary units, receive to have obtained the whole audience information of transmission signal by K-K
5. according to claim 4 be used for the received frequency deviation estimating method of K-K, which is characterized in that step S22 includes：It is first
First, to the whole audience information of transmission signal4 power operations are carried out, Fast Fourier Transform (FFT) is then carried out to it, are found in Fu
Maximum spectrum component in leaf frequency spectrum, frequency deviation is related to maximum spectrum component, according to maximum spectrum component carry out offset estimation with
Restore.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111478734A (en) * | 2019-01-24 | 2020-07-31 | 西安电子科技大学 | Low intermediate frequency photon broadband radio frequency receiving method based on K-K detection |
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| CN106101044A (en) * | 2016-06-01 | 2016-11-09 | 中国电力科学研究院 | A kind of frequency deviation estimating method based on multistep interpolation for coherent optical communication system |
| WO2017212492A1 (en) * | 2016-06-08 | 2017-12-14 | Ramot At Tel-Aviv University Ltd. | Kramers-kronig receiver |
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2018
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| CN105207043A (en) * | 2015-09-23 | 2015-12-30 | 北京邮电大学 | Photoelectric oscillator |
| CN106101044A (en) * | 2016-06-01 | 2016-11-09 | 中国电力科学研究院 | A kind of frequency deviation estimating method based on multistep interpolation for coherent optical communication system |
| WO2017212492A1 (en) * | 2016-06-08 | 2017-12-14 | Ramot At Tel-Aviv University Ltd. | Kramers-kronig receiver |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111478734A (en) * | 2019-01-24 | 2020-07-31 | 西安电子科技大学 | Low intermediate frequency photon broadband radio frequency receiving method based on K-K detection |
| CN111478734B (en) * | 2019-01-24 | 2021-08-20 | 西安电子科技大学 | Low intermediate frequency photon broadband radio frequency receiving method based on K-K detection |
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Application publication date: 20181123 |