CN1327623C - Symbol detection and inhibiting method of phase noise in multi-carrier signaling system - Google Patents
Symbol detection and inhibiting method of phase noise in multi-carrier signaling system Download PDFInfo
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Abstract
The present invention provides a symbol-by-symbol detection and suppression method for the phase noise of a receiver in a multi-carrier communication system. Through adding a definitely quantitative of phase noise detecting sub-carrier groups at both ends of a channel passband of the sending end, the receiving end obtains the phase noise influencing symbols by distortion caused by the self-vibration phase noise of the received end of the detecting sub-carrier groups and by a deconvolution method, and solved information is used for suppressing the phase noise of the symbols effectively symbol by symbol. The method can be used for effectively estimating and suppressing low-frequency noise and most high-frequency noise introduced by the phase noise. Before channel estimation and equalization, the method of the present invention complete the tracking and the suppression of the phase noise symbol by symbol, the later processing of information symbols only considers deformation introduced by a channel, and thereof, the method is favorable to improve the performance of the multi-carrier communication system.
Description
Technical field:
The invention belongs to communication technical field, particularly the treatment technology of the phase noise that oscillation source is introduced in the multi-carrier communications systems.
Background technology:
OFDM (being called for short OFDM) technology based on multi-carrier scheme is one of the most promising modulation-demodulation technique of communication technical field.The OFDM technology is that the information code current that speed is very high is divided into many low speed code streams, carries out the technology of parallel transmission on the subchannel of one group of quadrature.Adopt the OFDM technology can expand the width of subchannel transmission symbol, thus the design of equalizer in the simplified receiver greatly.The OFDM technology adopts guardtime (to be called for short TGI) at interval and removes intersymbol interference (being called for short ISI) effectively simultaneously, disturbs thereby overcome the multipath that is shorter than TGI.On the other hand, the OFDM technology is utilized the orthogonality between subcarrier, has improved the availability of frequency spectrum effectively.This is the major advantage of OFDM technology.
But the OFDM modulation system to transmitting-receiving local oscillator phase noise (be called for short and make an uproar mutually) than the single-carrier system sensitivity many, this is one of shortcoming of OFDM.Oscillator make an uproar mutually be exactly various imperfect physical factors to stablizing the Stochastic Modulation of sinusoidal waveform phase place, show as to phase place the time become dry and to disturb.The Mathematical Modeling of making an uproar mutually is that a dimension is received random process, and make an uproar the mutually influence that produces is a random value by symbol to system.So will follow the tracks of by symbol ground to the processing of making an uproar mutually, suppress by symbol ground, could eliminate the influence of making an uproar mutually to system.
In the multi-carrier communications systems to multiple spot, transmitter local oscillator quality is higher on one point, and the level of making an uproar mutually is lower, so when considering to make an uproar mutually, that only considers generally that receiver local oscillator low-converter introduces makes an uproar mutually.Fig. 1 is that the typical case of ofdm system receiver radio frequency front end constitutes (list of references: Claus Muschallik, " Influence of RF oscillatorson an OFDM signal; " IEEE Trans.Consumer Electronics, vol.41, No.3, pp.592-603, August1995.), wherein voltage controlled oscillator (being called for short VCO) has been introduced and has been made an uproar mutually and carrier frequency shift (being called for short CFO).CFO is by the Frequency Synchronization cell processing of receiver, so making an uproar mutually of only considering when VCO influences to introduce is discussed here.Radiofrequency signal is received by antenna, by low noise amplification, bandpass filtering the signal that needs frequency range is taken out.Bandpass signal becomes intermediate-freuqncy signal by receiver down converter, becomes digital baseband signal by intermediate frequency amplification, surface acoustic wave (being called for short SAW) bandpass filtering, quadrature frequency conversion and mould/number conversion again, carries out Digital Signal Processing at last.Digital signal processor provides automatic frequency control (AFC) signal to suppress the interference of relatively low frequency in the VCXO (being called for short VCXO).Phase noise is introduced by local oscillator voltage controlled oscillator (being called for short VCO), and the feasible low frequency component of making an uproar mutually of phase-locked loop frequency stabilization obtains certain inhibition.
The broad band tuner of some communication system (as television system) shows higher making an uproar mutually, be because its commercial inductor capacitor resonant circuit quality factor q value is lower on the one hand, reason on the other hand is the white noise of introducing from the resistance of connecting with variable capacitance diode.Making an uproar mutually is a kind of time domain multiplicative noise, have a strong impact on that (disturb between subcarrier, ICI), particularly higher (number of sub carrier wave is big for band efficiency with the form of frequency domain convolution the ofdm system performance being produced immediately after the local oscillator, subcarrier QAM order of modulation height) time, its influence is more serious.The Base-Band Processing part is handled making an uproar mutually in system, can relax the designing requirement to the receiver local oscillator, thereby effectively reduce development cost.
The short-term frequency stability characteristics of making an uproar mutually and having characterized oscillation source is generally described with the monolateral band power spectral density of offset carrier.Phase noise cancellation metric unit implication is: the power spectral density (being called for short PSD) of making an uproar mutually during as " 67dBc/Hz@2kHz " expression offset carrier 2 KHz is-67dBc/Hz, promptly in every hertz noise power than the low 67dB of carrier wave.Fig. 2 is make an uproar the mutually measured curve of characteristic of typical oscillation source, and the one-sided power spectrum density of as can be seen from the figure making an uproar mutually descends rapidly along with the increase of offset carrier frequency.But in the design of receiver front end frequency synthesizer, generally use phase-locked loop (being called for short PLL) to improve the stability characteristic (quality) of VCO.The introducing of PLL changes the curve of making an uproar mutually shown in Figure 2 because of suppressing low-frequency noise, makes low frequency part more smooth (as Fig. 3), and three segment tables that can be approximated to Fig. 4 to the curve of making an uproar mutually after the PLL locking show.Parameter according to Fig. 4 can be discussed the influence of making an uproar mutually to ofdm system qualitatively.
Fig. 4 medium and low frequency flex point f
LGenerally in a few kHz magnitudes, and high frequency flex point f
HIn hundreds of kHz magnitude.When dividing phase separation to make an uproar, with OFDM modulated sub-carriers f at interval to the influencing of system
sBe the boundary, less than f
sMake an uproar the mutually low-frequency noise introduced of part causes the rotation of whole signal constellation (in digital modulation); Greater than f
sMake an uproar the mutually high-frequency noise introduced of part causes that the cloud form of signal constellation point disperses, and causes the loss of orthogonality between subcarrier, makes the signal to noise ratio of system descend.In two kinds of influences, often the influence of the low-frequency noise of making an uproar is mutually called common phase error (being called for short CPE) in the above, and the influence of the high-frequency noise of making an uproar mutually is called between subcarrier and disturbs (being called for short ICI).At present, can only correct CPE to the processing of making an uproar mutually in ofdm system, this method is called CPEC (CPE Correction), its basic principle such as Fig. 5.CPEC estimates that the method for making an uproar mutually with pilot tone solves.After the receiving end FFT demodulation, extract the pilot sub-carrier of making a start, estimate the CPE value of the low-frequency noise introducing of making an uproar mutually according to the distortion of pilot sub-carrier
CPEThen data subcarrier be multiply by e
-j CPETo finish the compensation of making an uproar mutually.Therefore after handling with the CPEC method, residue is made an uproar influence to system mutually just by f
LAnd f
sRelation decision.If f
LLess than f
s, the influence of CPE will occupy main status, and CPEC can eliminate the overwhelming majority influence of making an uproar mutually; Otherwise the influence of ICI will occupy main status, because the CPEC method can not be handled the high-frequency noise of making an uproar mutually, so this method lost efficacy.So traditional CPEC method is very halfway to the inhibition of making an uproar mutually, can not fundamentally eliminate the influence of making an uproar mutually to ofdm system.
Summary of the invention:
The purpose of this invention is to provide make an uproar mutually in a kind of multi-carrier communications systems by symbol detection and inhibition method, it not only can accurately correct CPE, can also estimate preferably and the high-frequency noise that suppresses to make an uproar mutually and introduce, make an uproar mutually to the influence of ofdm system thereby eliminate more up hill and dale.
Make an uproar mutually in the multi-carrier communications systems provided by the invention by symbol detection and inhibition method, its operation principle as shown in Figure 6, its adopts following treatment step:
Step 3 is estimated thick common phase error value from the monitoring subcarrier that receives, promptly thick CPE value, and thick CPE value is designated as
CEP_C, described thick CPE value is meant with real CPE value and differs bigger CPE estimated value:
Ф wherein
iBe the phase place of the monitoring subcarrier that receives, θ
iBe the first phase of the monitoring subcarrier of making a start, subscript i is a natural number, span 1～2N.
Feature of the present invention is that it also comprises following step:
It is P that step 4 is established the high frequency sideband vector of making an uproar mutually, smart common phase error value, and promptly smart CPE value is
CPE_F, the making a start monitoring subcarrier vector of making an uproar mutually is T, described smart CPE value is meant with CPE value really and differs less CPE estimated value, then can obtain following overdetermined equation:
Wherein represents linear convolution.Utilizing the relation of making an uproar mutually between sideband is that conjugation is got negative relation with equation (2) abbreviation, obtains P and with singular value decomposition (being called for short SVD) method
CPE_F, obtain total common phase error value then, promptly total CPE value is designated as
CPE:
CPE＝
CPE_C+
CPE_F (3)
PP
-1＝δ (4)
The central value of its frequency domain unit impulse function vector delta is 1, and all the other are zero; From equation (4), can solve P
-1
Through behind the above treatment step, system just can realize to make an uproar mutually by symbol tracking, and when correcting CPE better, the inhibition overwhelming majority high-frequency noise of making an uproar mutually.
Above step need to prove:
The time domain multiplicative noise of making an uproar mutually that local oscillator is brought, removing it at frequency domain with the form of deconvolution immediately after the receiving terminal local oscillator produces to have a strong impact on to the ofdm system performance and (comprises common phase error, disturb between CPE and subcarrier, ICI), the information source of frequency domain deconvolution is the detection sub carrier group of making an uproar mutually described in the step 1, by present the interfere information of making an uproar mutually after the FFT conversion in frequency domain;
In step 3-5, adopted two step methods of estimation of all unknown quantitys of thick CPE, smart CPE and the high frequency sideband of making an uproar mutually, and utilized the conjugation of making an uproar mutually between sideband to get negative relation equation (2) abbreviation is found the solution, improve solving precision and reduced amount of calculation;
In step 6, to the data subcarrier after the FFT demodulation, carried out the compensation of making an uproar mutually with the form of frequency domain deconvolution, thereby effectively suppress the local oscillator phase noise having a strong impact on of ofdm system performance generation (comprised common phase error by symbol ground, disturb between CPE and subcarrier, ICI).
That therefore, makes an uproar mutually in the multi-carrier communications systems of the present invention can fundamentally eliminate the influence of making an uproar mutually to system by symbol detection with the inhibition method.
The multi-carrier communications systems phase noise that the present invention proposes is by symbol detection and inhibition method, its essence is by add the detection subcarrier of making an uproar mutually of some at the channel passband two ends, receiving end is according to the distortion of surveying subcarrier, utilizing the method for deconvolution to try to achieve influences making an uproar mutually of this symbol, and effectively suppresses making an uproar mutually with the information that solves.
Survey subcarrier and 5 space subcarriers with each 5 at channel passband two ends below, promptly N=5 is the operation principle that example is narrated the inventive method.
(1) thick CPE estimates and compensation
To the CPE that the low-frequency noise of making an uproar is mutually introduced, in order to improve estimated accuracy, this method is estimated in two steps: the first step is estimated thick CPE value (the CPE value is meant the angle of signal constellation (in digital modulation) rotation); Second step was estimated residue CPE, promptly smart CPE value (a small amount of).When smart CPE value is estimated, most high-frequency noises (being ICI) have also been estimated.
Surveying the sub carrier group data extract with making an uproar mutually from the data after the FFT demodulation comes out, owing between they and information subcarrier certain intervals is arranged, so can think makes an uproar mutually surveys sub carrier group and only is subjected to make an uproar mutually and influences, and is not subjected to the information subcarrier because the influence that the convolution of making an uproar mutually produces.Therefore the ten-four owing to make a start on this sub carrier group can therefrom solve relevant information of making an uproar mutually.
Can know each monitoring subcarrier be subjected to make an uproar mutually phase place Ф after disturbing from receiving data
i, it is deducted its first phase θ
i(can know from the Given information of making a start) just obtains phase difference, and wherein subscript i represents to survey the subcarrier label, gets natural number 1～10.10 subcarriers of making an uproar mutually can get 10 phase differences, and phase difference has on average just been obtained thick CPE value
CPE_C(being equation (1)).It is exactly to multiply by e that the detection subcarrier information is carried out thick CPE compensation
-j CPE_C
(2) smart CPE estimates and part ICI estimation
The power spectral density of making an uproar mutually is that continuous distribution and offset carrier are quick downward trend (as Fig. 2).Because the sampling of multicarrier system frequency domain, make the PSD discretization of continuous distribution, like this we just can frequency domain simply with about limited sideband come to carry out modeling to making an uproar mutually, limited sideband represented with vector P.Interval between its Intermediate Side Band equates with the multicarrier system subcarrier spacing.The ratio that the HFS energy accounts for owing to make an uproar mutually seldom, so limited lower sideband can have been satisfied the requirement of systematic function to the estimated accuracy of making an uproar mutually.
Making an uproar mutually is the time domain multiplicative noise, so be the process of rolling up mutually with the known information of making a start (being made as vector T) at frequency domain.Limited the sideband of frequency domain low frequency of making an uproar mutually is made as unknown number P, and it does convolution algorithm with the known information of surveying the sub carrier group load of making an uproar mutually is exactly the information (being made as vector R) that receiving end obtains.When finding the solution P, extract make an uproar mutually monitoring subcarrier data and several gap carrier data of closing on of receiving end in the lump, because the gap carrier wave contains the high frequency side information of making an uproar mutually.So just can obtain a convolution equation (being equation (2)), therefrom just can solve the frequency domain information of making an uproar mutually.
Convolution equation is an overdetermined equation, can try to achieve minimum variance with the SVD method and separate.The number of unknown number is few more in the equation, and the precision of separating is just high more.So reduce the number of equation unknown number is to improve the key of algorithm performance.
The restriction relation that goes up between lower sideband of making an uproar mutually after can utilizing thick CPE to compensate reduces equation unknown number number.After the thick CPE compensation, making an uproar mutually on the carrier frequency is made as real number, the small anglec of rotation of constellation (smart CPE value) is placed in the data after CPE compensates to be considered.Satisfy conjugation between the last lower sideband of correspondence about offset carrier and get negative relation, so just can make the number of equation unknown number reduce half, thereby improve the solving precision of making an uproar mutually greatly.
We just can solve effectively to make an uproar mutually and go up the information of lower sideband in the overdetermined equation that obtains from above, and the thick CPE compensation remaining smart CPE value in back
CPE_FThe side information up and down here is exactly the most ICI that high-frequency noise introduces that make an uproar mutually.Offset carrier descends fast owing to make an uproar mutually, so limited side information can suppress ICI to enough degree.
(3) compensation of making an uproar mutually
After solving the relevant frequency domain information of making an uproar mutually, also to solve the contrary P that makes an uproar mutually
-1Could compensate making an uproar mutually in the information symbol.That makes an uproar mutually contrary is meant that the anti-phase convolution of making an uproar mutually and making an uproar mutually obtains the impulse function of a frequency domain.Asking the contrary problem of making an uproar mutually is a problem of finding the solution overdetermined equation (4).
The compensation of making an uproar is mutually carried out in two steps: it is exactly the CPE value that finally is used for the compensated information symbol that the CPE value that will estimate in thick smart two steps lumps together
CPE(being equation (3)) just can carry out the CPE compensation to information symbol with this value, promptly multiply by e
-j CPETo the compensation of high-frequency noise ICI, do convolution algorithm one time with the information data after the contrary and CPE compensation of making an uproar mutually that solves exactly.So just finished the compensation of make an uproar mutually low-frequency noise and part high-frequency noise.
From above principle Analysis as can be seen, that makes an uproar mutually in the multi-carrier communications systems provided by the invention compares with the CPEC method with the inhibition method by symbol detection, has following characteristics:
1) this method adopted for two steps estimated CPE, so correct more thorough for CPE;
2) most ICI that the estimation of the high frequency sideband of making an uproar is mutually made this method to eliminate to make an uproar mutually and introduce;
3) estimate that the algorithm of making an uproar mutually with compensation is fairly simple, the hardware costs of paying is less.
In sum, that makes an uproar mutually in the multi-carrier communications systems provided by the invention can pursue the phase noise that symbol tracking/suppression receiver local oscillator is introduced effectively by symbol detection and inhibition method, has fundamentally solved the problem of making an uproar mutually in the ofdm system.
Description of drawings:
Fig. 1 multicarrier system receiver radio frequency front end constitutes
Wherein, Antenna represents antenna, and Tuner represents tuner, and IF Amplifier represents intermediate frequency amplifier, and SAW represents Surface Acoustic Wave Filter, and VCO represents voltage controlled oscillator.
Fig. 2 oscillation source characteristic measured curve of making an uproar mutually
The oscillation source characteristic measured curve of making an uproar mutually behind Fig. 3 phase-locked loop frequency stabilization
1 flat that points to is represented the low frequency part of making an uproar mutually among the figure.
Make an uproar the mutually approximate representation of power spectral density plot of Fig. 4
F among the figure
LRepresent to make an uproar mutually the low frequency flex point, f
HExpression high frequency flex point.
Fig. 5 CPEC method theory diagram
Fig. 6 makes an uproar mutually and surveys the distribution of sub carrier group
Fig. 7 make an uproar mutually by symbol detection and inhibition method schematic diagram
Fig. 8 embodiment simulated program flow chart
Fig. 9 emulation monolateral band power spectral density (PSD) curve of making an uproar mutually
Among the figure, the power spectral density of making an uproar mutually when 2 expression offset carrier frequency are a subcarrier spacing :-67dBc/Hz; The power spectral density of making an uproar mutually when 3 expression offset carrier frequency are two subcarrier spacings :-72dBc/Hz; The power spectral density of making an uproar mutually when 4 expression offset carrier frequency are 100 subcarrier spacings :-113dBc/Hz.
Signal constellation which after Figure 10 phase noise disturbs
Signal constellation which after Figure 11 CPEC method is handled
Figure 12 make an uproar mutually by the signal constellation which after the processing of symbol detection and inhibition method
The symbol error performance that Figure 13 makes an uproar mutually by symbol detection and inhibition method
5 expression systems are subjected to making an uproar mutually and disturb but do not carry out symbol error rate curve under any treatment conditions to making an uproar mutually among the figure, 6 expression CPEC methods are corrected the symbol error rate curve of the back system that makes an uproar mutually, 7 expressions are made an uproar mutually by the symbol error rate curve of symbol detection and inhibition method processing back system, the desirable symbol error rate curve of system when interference is not made an uproar in 8 expressions mutually.
Embodiment
That makes an uproar mutually in the multi-carrier communications systems provided by the invention can pass through the DSP circuit by symbol detection and inhibition method, or field programmable gate array (being called for short FPGA) (as the Stratix Series FPGA of altera corp) is realized, also can be realized by application-specific integrated circuit (ASIC) (ASIC).No matter adopt any method, all need design by software systems emulation and verify that the method with software emulation provides an embodiment here, and the result that this method provides can be comprehensive by the software conversion, be mapped as one of above-mentioned realization.Simulation software adopts Matlab 6.1, and program flow diagram as shown in Figure 8.In order simplifying, not consider the Cyclic Prefix (be called for short CP) in the ofdm system in the emulation, and to think ideal synchronisation, what channel condition was considered is additive white Gaussian noise channel (being called for short AWGN).
Simulation parameter:
Nominal number of sub carrier wave: 4096
The OFDM symbol period:
Second, promptly subcarrier spacing is 2.124kHz
Information number of sub carrier wave: 3584
Containing makes an uproar mutually surveys subcarrier at interior number of sub carrier wave: 3584+20=3604
Channel width: 8MHz
Transmission bandwidth: 3604 * 2124=7.654896MHz
Protection bandwidth: 172.552kHz
Sampling frequency: 4096 * 2124=8.699904MHz
Consider to make an uproar mutually and go up the lower sideband number: go up each 2 of lower sidebands, add totally 5 of carrier waves
The level :-67dBc/Hz@2kHz that makes an uproar mutually ,-72 dBc/Hz@4kHz
-112 dBc/Hz@200kHz (Fig. 9 has provided the monolateral band PSD curve of making an uproar mutually)
It is that the both sides of information sub-carrier band are respectively put one and made an uproar mutually and survey an example of sub carrier group that Fig. 6 has provided at passband two ends, every group adds 5 detection subcarriers in Fig. 6, survey between subcarrier and the information subcarrier and vacate 5 subcarrier spacings, can ignore the information subcarrier like this to surveying the influence of subcarrier, when consider surveying the interference that subcarrier is subjected to, just only consider phase noise.
Figure 10～13 have provided simulation result.
Figure 10～12nd, bit signal to noise ratio are 40dB, the signal constellation which that obtains during 64 rank quadrature amplitude modulation (64QAM).Signal constellation which is made up of in-phase component and quadrature component, and they have represented the amplitude and the phase place of signal jointly.During the 64QAM modulation, if desirable fully transmission, then planisphere has 64 constellation point.Because the influence of making an uproar mutually makes desirable constellation point disperse.Signal constellation point is convergence more, and the distance between them is just big more, just can differentiate constellation point better, and then the error rate will be low more.As can be seen from Figure 10, when not carrying out any processing to making an uproar mutually, making an uproar mutually has two kinds of influences to system: the dispersing of the rotation of whole constellation and signal constellation point.As shown in Figure 11, after the CPEC method was handled making an uproar mutually, the rotation of planisphere had been repaired, but dispersing still of constellation point exists.So, the CPEC method can only handle make an uproar mutually introduce less than the low-frequency noise in the subcarrier spacing frequency range, powerless to the high-frequency noise of making an uproar mutually.With making an uproar mutually, know the rotation of not only having corrected planisphere by Figure 12, and signal constellation point restrains manyly than Figure 11 by after symbol detection and the inhibition method.So the CPE that this method has not only suppressed to make an uproar mutually and introduced has also suppressed most high-frequency noises, makes systematic function take on a new look greatly.Signal constellation which intuitively showed by symbol make an uproar mutually detect with compensation method be effectively, much more superior than conventional CPEC method.
Ber curve can well reflect the performance of system.Figure 13 is the symbol error rate curve that obtains under above-mentioned simulated conditions.Symbol error rate is low more, and the performance of illustrative system is just good more.As can be seen from Figure 13, during low signal-to-noise ratio (it is close that bit signal to noise ratio Eb/No＜15dB) only corrects CPE method performance by symbol compensation method and routine.At SER is 10
-4The time, worsen about 0.8dB with not making an uproar mutually to compare, but be better than the about 1.2dB of CPEC method.And the CPEC method has " residue error code " phenomenon, after promptly signal to noise ratio is higher than about 22dB, improves signal to noise ratio the error rate is not obviously improved.This is because this algorithm has only been corrected low-frequency noise, and high-frequency noise is not had inhibitory action, and the high-frequency noise of making an uproar mutually just is equivalent to the level of channel 22dB Gaussian noise, so " residue error code " phenomenon occurred.That makes an uproar mutually can obtain very high processing gain (particularly when the interference of making an uproar mutually is big) by symbol detection and inhibition method, compares with the algorithm that can only handle CPE of routine, and it is much superior that this method is also wanted.
Claims (1)
1. make an uproar mutually in the multi-carrier communications systems by symbol detection and inhibition method, its adopts following treatment step:
Step 1 respectively increases N continuous sub-carriers group as the phase noise monitor signal at channel passband two ends of making a start, and is also used as running parameter signaling group and uses; The interval of making an uproar mutually between detection sub carrier group and the information subcarrier keeps N subcarrier space; The purpose of reserving the subcarrier space is that avoiding surveying the convolution that causes by making an uproar mutually between subcarrier and the information subcarrier disturbs; Wherein, passband two ends are meant the two ends of information sub-carrier band, and the size of N depends on the requirement of system for the processing accuracy of making an uproar mutually;
Step 2 is make an uproar mutually a modulation intelligence on monitoring sub carrier group and the contiguous several gap carrier waves of extracting data after the FFT demodulation from the fast fourier transform demodulation, is made as data vector R;
Step 3 is estimated thick common phase error value from the monitoring subcarrier that receives, promptly thick CPE value, and thick CPE value is designated as first
CPE_C, wherein said thick CPE value is meant with real CPE value and differs bigger CPE estimated value:
Φ wherein
iBe the phase place of the monitoring subcarrier that receives, θ
iBe the first phase of the monitoring subcarrier of making a start, subscript i is a natural number, span 1～2N;
Feature of the present invention is that it also comprises following step:
It is P that step 4 is established the high frequency sideband vector of making an uproar mutually, smart common phase error value, and promptly smart CPE value is
CPE_F, the making a start monitoring subcarrier vector of making an uproar mutually is T, described smart CPE value is meant with CPE value really and differs less CPE estimated value, then can obtain following overdetermined equation:
Wherein represents linear convolution; Utilize the relation of making an uproar mutually between sideband with the overdetermined equation abbreviation in the step 4, obtain P and with singular value decomposition method
CPE_F, obtain total common phase error value then, promptly total CPE value is designated as
CPE:
CPE＝
CPE_C+
CPE_F
Step 5 is established the contrary P of being of the high frequency sideband vector of making an uproar mutually
-1, can obtain following overdetermined equation:
PP
-1＝δ
The central value of its frequency domain unit impulse function vector delta is 1, and all the other are zero; Can solve P in the equation from step 5
-1
Step 6 pair fast fourier transform demodulation is the compensation of making an uproar mutually of the data subcarrier after the FFT demodulation: at first each subcarrier be multiply by e
-j CPE, to compensate the common phase error that the low-frequency noise of making an uproar is mutually introduced; With data and the vector P after the common phase error compensation
-1Do convolution one time, just can be compensated the data behind the high-frequency noise of making an uproar mutually;
Through behind the above treatment step, system just can realize pursuing symbol tracking and inhibition to what make an uproar mutually.
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| CN103095405A (en) * | 2012-11-19 | 2013-05-08 | 西安理工大学 | Method for restraining multiplicative noise in wireless optical communication system |
| CN103414461A (en) * | 2013-06-27 | 2013-11-27 | 深圳市创成微电子有限公司 | RFID low noise PLL (Phase Locked Loop) technology |
| CN112148059B (en) * | 2020-10-12 | 2022-07-05 | 四川科陆新能电气有限公司 | MPPT maximum power tracking method for photovoltaic power station |
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| CN1171666A (en) * | 1996-07-05 | 1998-01-28 | 德国汤姆逊-布朗特公司 | Method for frequency correction of multicarrier signals and related apparatus |
| CN1213920A (en) * | 1997-09-04 | 1999-04-14 | 德国汤姆逊-布朗特公司 | Method and circuit arrangement for correction of phase and/or frequency errors in digital multicarrier signals |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1171666A (en) * | 1996-07-05 | 1998-01-28 | 德国汤姆逊-布朗特公司 | Method for frequency correction of multicarrier signals and related apparatus |
| CN1213920A (en) * | 1997-09-04 | 1999-04-14 | 德国汤姆逊-布朗特公司 | Method and circuit arrangement for correction of phase and/or frequency errors in digital multicarrier signals |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103460609A (en) * | 2011-02-08 | 2013-12-18 | 伊卡诺斯通讯公司 | System and method for improving spectral efficiency and profiling of crosstalk noise in synchronized multi-user multi-carrier communications |
| CN103460609B (en) * | 2011-02-08 | 2016-06-29 | 伊卡诺斯通讯公司 | For improving spectrum efficiency in Synchronous Multi-User multi-carrier communication and dissecting the system and method for crosstalk noise |
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