CN106911607A - The unbalanced method of estimation of inphase/orthogonal and its module in a kind of ofdm system - Google Patents

The unbalanced method of estimation of inphase/orthogonal and its module in a kind of ofdm system Download PDF

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CN106911607A
CN106911607A CN201510975406.6A CN201510975406A CN106911607A CN 106911607 A CN106911607 A CN 106911607A CN 201510975406 A CN201510975406 A CN 201510975406A CN 106911607 A CN106911607 A CN 106911607A
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estimation
subcarrier
imbalance
inphase
orthogonal
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CN106911607B (en
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曹伟
康凯
钱骅
杨旸
胡宏林
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Shanghai Research Center for Wireless Communications
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Shanghai Research Center for Wireless Communications
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/26—Systems using multi-frequency codes
    • H04L27/2601—Multicarrier modulation systems
    • H04L27/2647—Arrangements specific to the receiver only
    • H04L27/2655—Synchronisation arrangements
    • H04L27/2657—Carrier synchronisation
    • 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
    • H04L27/2668—Details of algorithms
    • H04L27/2673—Details of algorithms characterised by synchronisation parameters
    • H04L27/2675—Pilot or known symbols
    • 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
    • H04L27/3863—Compensation for quadrature error in the received signal

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  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention discloses the unbalanced method of estimation of inphase/orthogonal and its module in a kind of ofdm system.The method of estimation is comprised the following steps：S1：Time-domain signal to receiving carries out frequency deviation compensation；S2：After removal Cyclic Prefix, two times upper neighbouring different frequency pilot signs are transformed into frequency domain；S3：The subcarrier that frequency pilot sign takes is extracted according to system bandwidth；S4：For two frequency pilot signs, the reception signal of two pilot signals on each subcarrier is obtained；S5：The coupling of removal IQ imbalance parameters and channel, asks for IQ imbalance estimates.Not only wide application of the invention, the timing requirements for receiver treatment are low；And meeting most of practical application scene demand, algorithm is simple, and amount of calculation is small.

Description

The unbalanced method of estimation of inphase/orthogonal and its module in a kind of ofdm system
Technical field
The present invention relates to one kind in OFDM (OFDM) system, to inphase/orthogonal (In-phase/Quadrature-phase, referred to as IQ) method for being estimated of imbalance and Its module, belongs to wireless communication technology field.
Background technology
In common ofdm communication system (such as 802.11a/g/n/ac series and LTE), In order to lift spectrum utilization efficiency, high order modulation or MIMO technology are generally employed.These are complicated Transmission plan requirement receiver can obtain of a relatively high signal to noise ratio (SNR).And transceiver is received It is limited to production cost, it may be necessary to using the device of more low price, its nonideal IQ is uneven special Property can cause the signal to noise ratio of receiving terminal to decline, and have a strong impact on receptivity.In order to lift receptivity, It is necessary to estimate IQ imbalances to compensate receiving terminal exactly.
For the wide-band communication system based on OFDM technology, itself divides whole frequency band Often use and grasped in frequency domain into multiple subcarriers, therefore common IQ imbalance methods of estimation Calculate.For example estimate for the IQ in ofdm system is uneven, Broadcom Corp is in the U.S. Patent application " IQ imbalance estimation using broadcast signals " is (public The number of opening is US2015103960A1) in be based on symmetrical pilot configuration, it is proposed that using symmetrical on DC Paired pilot sub-carrier obtain statistic, then this statistic is supplied to channel estimation module Channel estimation is asked for, the result of channel estimation finally is delivered into IQ imbalance estimation modules is used to eliminate Uneven and channel information the couplings of IQ, obtain IQ imbalance estimates of parameters.It is required that pilot signal Design be symmetrical on DC, this is larger for the limitation of system pilot Design of Signal.For example, In some communication standards of UMTS LTE, because pilot tone is not disposed in symmetrical frequency, then this side Method is not applied to.Also, the patent application needs first to complete pilot channel estimation, then could estimate IQ is uneven, therefore sequential to implementing is required.Further, the patent application is estimated in channel Assume that adjacent sub-carrier channel is flat in meter, this is assumed for less subcarrier spacing, for example LTE system (subcarrier spacing is 15kHz) is more reasonable；And for there is larger subcarrier spacing For ofdm system, such as 802.11a/g/n/ac systems (subcarrier spacing is 312.5kHz), Then the hypothesis may not be set up.
In order to remove dependence of the IQ imbalance algorithm for estimating for symmetrical pilot configuration, Ericsson In notification number for the Chinese invention patent of CN102057644B " is used to estimate the unbalanced methods of IQ And arrangement " in, proposition substitutes portion of pilot symbol using data symbol, that is, constitute on DC pairs The pilot/data subcarrier pair of title, is used to estimate that IQ is uneven, its main thought is with above-mentioned Botong The patent application of company is similar, it is necessary to the data symbol that will be used carries out channel estimation and demodulation, It is then viewed as known symbol (being equivalent to pilot tone).This method has following weak point：Need first complete Into data symbol demodulation, then could estimate that IQ is uneven, thus sequential to implementing have will Ask, and complexity is higher；Channel estimation on data symbol is typically inserted by the channel estimation in pilot tone Value is produced, and itself causes the uneven accuracy estimated of IQ containing IQ imbalances and interpolation error Not as directly using symmetrical pilot signal；Data symbol demodulation then can directly be led in the event of mistake Cause the uneven estimation errors of IQ.
Ericsson is in notification number for another Chinese invention patent of CN102668483B " is used for The IQ of asymmetric frequency pilot sign is uneven to be estimated " in, propose that uneven based on IQ is static parameter It is assumed that receive ofdm signal initial stage downwards be mixed when add extra frequency shift (FS) so that Symmetrical pilot sub-carrier is obtained in baseband signal (this time-frequency spectrum shifts, no longer centered on DC). Then using the IQ imbalance algorithm for estimating based on symmetrical pilot tone, the extra frequency of compensation is finally also needed to Rate offsets.Obtain after IQ imbalance estimates, received using normal lower mixing, no longer enter Row IQ is uneven to be estimated.The method has following weak point：Need receiving the first of ofdm signal Phase uses different lower frequency mixing methods, and the frequency shift (FS) of extra addition is depended on specifically in lower mixing Pilot design, implementation complexity is high；Assuming that it is quiescent value that IQ is uneven, it is impossible to realize that IQ is uneven The real-time estimation of weighing apparatus；IQ is uneven in actual environment is also subject to the influence of the time-varying factors such as temperature, voltage, Therefore the utility values of the method must be discussed.
The content of the invention
Primary technical problem to be solved by this invention be provide same phase in a kind of ofdm system/ The method of estimation of quadrature imbalance.
Another technical problem to be solved by this invention be provide same phase in a kind of ofdm system/ The estimation module of quadrature imbalance.
For achieving the above object, the present invention uses following technical schemes：
The unbalanced method of estimation of inphase/orthogonal, comprises the following steps in a kind of ofdm system：
S1：Time-domain signal to receiving carries out frequency deviation compensation；
S2：After removal Cyclic Prefix, two times upper neighbouring different frequency pilot signs are transformed into frequency Domain；
S3：The subcarrier that the frequency pilot sign takes is extracted according to system bandwidth；
S4：For described two frequency pilot signs, the described two pilot tones letter on each subcarrier is obtained Number reception signal；
S5：The coupling of removal IQ imbalance parameters and channel, asks for IQ imbalance estimates.
Wherein more preferably, the coupling of IQ imbalance parameters and channel is removed in step S5, is one The ratio of IQ imbalance parameters is asked on the individual subcarrier
Wherein more preferably, tried to achieve respectively at least two subcarriers in the subcarrierWith On at least two subcarrierAverage value come ask for IQ imbalance estimate.
Wherein more preferably, tried to achieve respectively on each subcarrier in the subcarrierWith described On each subcarrierAverage value come ask for IQ imbalance estimate.
Wherein more preferably, it is further comprising the steps of：Upper neighbouring different pilot tones symbol of described two times Number, refer to two leading code sign STF and LTF.
Wherein more preferably, upper neighbouring different frequency pilot signs of described two times, refer to same carrier wave On two leading code sign STF and LTF.
The unbalanced estimation module of inphase/orthogonal in a kind of ofdm system, including：
Frequency offset compensation element：For carrying out frequency deviation compensation to the time-domain signal for receiving；
Removal cyclic prefix unit：For removing Cyclic Prefix；
Frequency-domain transform unit：For two times upper neighbouring different frequency pilot signs to be transformed into frequency domain；
Subcarrier extraction unit：For extracting the son load that the frequency pilot sign takes according to system bandwidth Ripple；And
ν/μ computing units：For to described two frequency pilot signs, obtaining the institute on each subcarrier Two reception signals of pilot signal are stated, the coupling of IQ imbalance parameters and channel is then removed, asked Take IQ imbalance estimates.
Wherein more preferably, the estimation module also includes ν/μ averaging units, for existing to ν/μ It is averaged on subcarrier.
Compared with prior art, the unbalanced method of estimation of inphase/orthogonal provided by the present invention and Its module has the following advantages that：
1. the dependence for symmetrical pilot configuration in conventional method is avoided, but is used on two times Neighbouring different frequency pilot signs, application surface is wider.
2. channel estimation and data demodulation need not be relied on, and the timing requirements for receiver treatment are low.
3. it is applicable for the scene for having frequency-selective channel, meeting most of practical application scene needs Ask.
4. algorithm is simple, and amount of calculation is small, it is easy to accomplish.
Brief description of the drawings
Fig. 1 is the flow chart element of IQ imbalance methods of estimation in ofdm system provided by the present invention Figure；
Fig. 2 is the simulation result that IQ imbalance parameter alphas are estimated；
Fig. 3 is the simulation result that IQ imbalance parameter θs are estimated；
Fig. 4 is the structured flowchart of IQ imbalance estimation modules in ofdm system provided by the present invention.
Specific embodiment
Technology contents of the invention are carried out with specific embodiment below in conjunction with the accompanying drawings specific in detail Explanation.
Present invention assumes that two different pilot tones neighbouring in existence time in ofdm system, the two are led Channel of the frequency signal on same subcarrier is flat.The hypothesis is in common ofdm communication system Generally set up in system.For example, the STF/LTF in (1) 802.11a/g/n/ac systems, when Between on be separated by 8us, for LAN environment, time correlation degree is very high；(2) PUSCH in LTE system On two row DMRS signals, containing different cyclic shifts, 0.5ms is separated by the time, for being less than During the common scene of 120km/h speed per hours, time correlation degree is higher.
Below this is illustrated by taking the IQ imbalance estimation procedures in 802.11a/g/n/ac systems as an example The unbalanced method of estimation of inphase/orthogonal in the provided ofdm system of invention. In 802.11a/g/n/ac systems, using 2 STF (short training in lead code Field, short training sequence) and 2 LTF (1ong training field, long training sequence) To estimate that IQ is uneven, treatment block diagram is as shown in Figure 1.
IQ provided by the present invention imbalance appraisal procedure in, it is assumed that α for IQ branch roads gain not Balance, θ is the unbalance in phase of IQ branch roads.μ, ν are as follows for defined variable：
It is readily obtained, if uneven without IQ, μ=1, ν=0.
As shown in figure 1, this method is comprised the following steps；
S1：Time-domain signal to receiving carries out frequency deviation compensation.
For frequency deviation, it is necessary to be estimated and compensated in advance.The step can use prior art Realize, will not be described here.
S2：After removal Cyclic Prefix, by two times upper neighbouring different frequency pilot signs (time rope Draw respectively n, m) transform to frequency domain.
Specifically, exactly carry out FFT the two frequency pilot signs transform to frequency domain by STF/LTF.
For in ofdm system containing IQ uneven and frequency-selective channel reception signal, due to IQ not The influence of balance, time-domain received signal is sd=μ s+ ν s*.Wherein s is unbalanced original without IQ Time-domain signal, s*Represent the conjugation of s, sdIt is to contain the unbalanced distortion time-domain signals of IQ.
By FFT to frequency domain, reception signal of the frequency pilot sign in time domain is obtained Sd=μ S+ ν Fconj (FHS)=μ S+ ν Z.Expressed to simplify, Z=Fconj (F defined in formulaHS).By It is known pilot in S, then Z can be with precalculated reducing real-time amount of calculation.
S3：The subcarrier that frequency pilot sign takes is extracted according to system bandwidth.
It is assumed herein that the number of sub carrier wave that the reception signal specifically takes is Nsubc.The step can be with Realized using prior art, will not be described here.It should be noted that receiving the son load that signal takes Wave number mesh Nsubc is different from sub-carrier number N, it is however generally that Nsubc<N, Nsubc are carried to take son Ripple, can be extracted calculating IQ uneven.Generally, Nsubc=48 (subcarrier bandwidth 80MHz)； Nsubc=24 (subcarrier bandwidth 40MHz)；Nsubc=12 (subcarrier bandwidth 20MHz).N is FFT size, generally comprise protection sideband.
S4：For two frequency pilot signs, two receptions of pilot signal on each subcarrier are obtained Signal.
Using the S and Z that obtain, for each frequency pilot sign, constitute a pair two on each subcarrier First linear function group.
In view of the influence of frequency-selective channel, receive signal and can be expressed as Sd2=H (μ S+ ν Z).H is The channel that each subcarrier is experienced.Wherein, S and Z can prestore in advance, be obtained by reading, To build linear equation in two unknowns group；Acquisition S and Z can also in real time be calculated.
Two time upper neighbouring different frequency pilot signs (time index is respectively n, m), i.e. STF/LTF The two leading code signs, can be considered flat, i.e. H in same subcarrier k upper signal channelsk,n=Hk,m。 Therefore, the reception letter of two pilot signals (time index is respectively n, m) on k-th subcarrier Number it is：
In known Sd2,k,n,Sd2,k,m,Sk,n,Sk,m,Zk,n,Zk,mIn the case of, it is apparent from μ Hk,n,νHk,nCan pass through The mode for solving linear equation in two unknowns is tried to achieve.From equation group, IQ imbalances are with channel couples one Rise, it is impossible to separate.
S5：The coupling of removal IQ imbalance parameters and channel, asks for IQ imbalance estimates.
In order to remove the coupling of IQ imbalance parameters and channel, it is possible to use simplify algorithm and ask for Therefore, the present invention chooses time upper two neighbouring different frequency pilot sign STF/LTF in ofdm system, The ratio of IQ imbalance parameters is asked on same subcarrier kCounteract channel Hk,nShadow Ring, realize the decoupling of IQ imbalance parameters and channel.
Although it has been observed that μ Hk,n,νHk,nCan be tried to achieve by way of solving linear equation in two unknowns, but In order to ask for IQ imbalance parameter alphas and θ, and above-mentioned linear equation in two unknowns, this hair need not be solved It is bright to use following method for simplifying：
In | α | ＜ ＜ 1, (the unbalanced typical value scopes of IQ, ginseng are more than under the hypothesis of | θ |≤5degree Examine document《Widely linear block-diagonalization type precoding in massive MIMO systems with IQ imbalance》, ICC 2015, p3392-3397, Jun 2015), can obtain such as lower aprons：
Therefore only need to calculateCan obtain and easily ask for IQ Uneven parameter alpha, θ.
Additionally, to improve estimated accuracy, this method of estimation is further included：It is rightSubcarrier is done to put down , lifting α, the estimated accuracy of θ.Because IQ imbalance parameters are slowly varying, can With by asking over the plurality of subcarriersAnd averagely improve α, the degree of accuracy that θ estimates.
Specifically, it is on each subcarrier, signal to be received based on STF/LTF and is tried to achieve Again by each subcarrierSummation, carries out arithmetic average.ObtainAverage, recycles formula (4) (5) α, θ valuations, so as to obtain IQ imbalance estimates are calculated.
Be apparent from, due to when influenceed on sub-carrierk unanimously for two different pilot tones partially, this method pair In when it is partially insensitive.Frequency deviation then needs to be estimated and compensated in advance.
Present invention could apply in ofdm system, realize the estimation for IQ imbalance parameters, So that receiving terminal is compensated for IQ imbalances.
Method of estimation provided by the present invention completely avoid in conventional method for symmetrical pilot configuration Dependence, simplify approximate using rational, ask for IQ imbalance parameter alphas, θ.Nothing in processing procedure Need channel estimation and data to demodulate, therefore realize low to receiver treatment timing requirements.This estimation Method for containing frequency-selective channel and when inclined scene, there is robustness in performance.Algorithm is transported Calculation amount is small, is especially advantageous for realizing.
The treatment branch of method of estimation provided by the present invention frequency deviation compensation after, independently of channel Estimate, channel equalization, the processing module such as data demodulation.Either in receiver or tester Upper application, this feature can optimize reception sequential.
By fixed-point simulation, method of estimation provided by the present invention is demonstrated in typical α, θ spans Interior estimation accuracy.Wherein linear value α be converted into dB expression formula be αdB=10*log10 (α+1).The 802.11a/g/n/ac specifications of survey in emulation according to to(for) modulating characteristic Order justice for a trial, the time for employing 20 frames (frame) averagely obtains accurate measurement result.
Emulation 1, mainly studies in different α, and (scope is more than the unbalanced typical values of IQ to θ values Scope) under, the degree of accuracy of algorithm and applicability.
Simulation parameter setting is as follows：
The mean square error of simulation result is as follows：
MSEα=0.0011dB
MSEθ=0.0207degree
IQ imbalance parameter alphas, the simulation result figure that θ estimates is given below.
As shown in Fig. 2 in given θ, (value is [- 5：5], 11 curves of correspondence) in the case of, α is [- 0.3：0.02：0.3] estimate accurate in the range of dB.What asterisk was marked in figure is for right The reference value of ratio, that is, the α values for setting.
As shown in figure 3, in given α, (value is [- 0.3：0.02：0.3] dB, correspondence 31 Curve) in the case of, θ is [- 5：5] estimate accurate in the range of degree.What asterisk was marked in figure is to use In the reference value of contrast, that is, the θ values for setting.
Emulation 2, mainly studies under typical α, θ values, the degree of accuracy of algorithm.
Simulation parameter setting is as follows：
The mean square error of simulation result is as shown in the table：
Be can see according to above-mentioned simulation result, same phase in ofdm system provided by the present invention/just Hand over unbalanced method of estimation accuracy high, meet actual demand.
Above by taking 802.11a/g/n/ac systems as an example, principle of the invention and implementation method are described. But, the specific embodiment should be considered as illustrative and not restrictive, and the present invention is not construed as It is limited to above-mentioned specific embodiment.In specific ofdm system, specific implementation of the invention can enter The corresponding change of row.For example, in LTE system, it is possible to use two row DMRS letters on PUSCH Number, as two time of the invention upper neighbouring different frequency pilot signs, frequency-domain transform is carried out, so Set up afterwards and receive signal set of equations.The ratio of the IQ imbalance parameters by asking for obtaining on subcarrier ValueTry to achieve the uneven estimation α, θ of IQ.Similar, it is also possible to by rightAsk on sub-carriers Averagely, precision is improved.
IQ imbalance methods of estimation suitable for ofdm system provided by the present invention, use Two different pilot signals on same subcarrier, using neighbouring OFDM symbol upper signal channel at any time Between change less feature, the influence of channel is offset.Simplify approximate by rational, significantly Amount of calculation is reduced, can exactly estimate that IQ is uneven finally by simulation results show this method Weighing apparatus.
The major advantage of above-mentioned method of estimation is：Do not require on DC symmetrical pilot configuration, no Depend on channel estimation and data to demodulate, there is robustness to frequency-selective channel, estimate to calculate Method amount of calculation is small to be easily achieved.
It is appreciated that the present invention also provides a kind of IQ imbalances estimation module, it is foregoing for realizing Each step in ofdm system IQ imbalance methods of estimation, so as to estimate IQ imbalance estimates.
Specifically, include with lower unit with reference to Fig. 1 and Fig. 4, IQ imbalance estimation module：
Frequency offset compensation element：For carrying out frequency deviation compensation to the time-domain signal for receiving；
Removal cyclic prefix unit：For removing Cyclic Prefix；
Frequency-domain transform unit：For two times upper neighbouring different frequency pilot signs to be transformed into frequency domain；
Subcarrier extraction unit：For extracting the son load that the frequency pilot sign takes according to system bandwidth Ripple；
ν/μ computing units：For to described two frequency pilot signs, obtaining the institute on each subcarrier Two reception signals of pilot signal are stated, the coupling of IQ imbalance parameters and channel is then removed, asked Take IQ imbalance estimates.
Be improve precision, ν/μ averaging units can also be increased, for ν/μ on sub-carriers It is averaged.
Above to the unbalanced method of estimation of inphase/orthogonal in ofdm system provided by the present invention And its module has been described in detail.For those of ordinary skill in the art, do not carrying on the back To any obvious change that it is done on the premise of the true spirit, all by structure Paired infringement of patent right of the present invention, will undertake corresponding legal liabilities.

Claims (10)

1. the unbalanced method of estimation of inphase/orthogonal in a kind of ofdm system, it is characterised in that including Following steps：
S1：Time-domain signal to receiving carries out frequency deviation compensation；
S2：After removal Cyclic Prefix, two times upper neighbouring different frequency pilot signs are transformed into frequency Domain；
S3：The subcarrier that the frequency pilot sign takes is extracted according to system bandwidth；
S4：For described two frequency pilot signs, the described two pilot tones letter on each subcarrier is obtained Number reception signal；
S5：The coupling of removal IQ imbalance parameters and channel, asks for IQ imbalance estimates.
2. the unbalanced method of estimation of inphase/orthogonal in ofdm system as claimed in claim 1, It is characterized in that：
The coupling of IQ imbalance parameters and channel is removed in step S5, is in a subcarrier On ask for IQ imbalance parameter ratio
3. the unbalanced method of estimation of inphase/orthogonal in ofdm system as claimed in claim 2, Characterized by further comprising following steps：
Tried to achieve respectively at least two subcarriers in the subcarrier
With at least two subcarrierAverage value come ask for IQ imbalance estimate.
4. the unbalanced method of estimation of inphase/orthogonal in ofdm system as claimed in claim 2, Characterized by further comprising following steps：
Tried to achieve respectively on each subcarrier in the subcarrier
With on described each subcarrierAverage value come ask for IQ imbalance estimate.
5. the unbalanced estimation side of inphase/orthogonal in ofdm system as claimed in claim 2 or claim 3 Method, it is characterised in that：
Upper neighbouring different frequency pilot signs of described two times refer to two leading code sign STF and LTF。
6. the unbalanced method of estimation of inphase/orthogonal in ofdm system as claimed in claim 5, It is characterized in that：
Upper neighbouring different frequency pilot signs of described two times refer to two lead codes on same carrier wave Symbol STF and LTF.
7. the unbalanced estimation side of inphase/orthogonal in ofdm system as claimed in claim 2 or claim 3 Method, it is characterised in that：
Upper neighbouring different frequency pilot signs of described two times refer to two on PUSCH in LTE system Row DMRS signals.
8. inphase/orthogonal is uneven in the ofdm system as described in any one in claims 1 to 3 The method of estimation of weighing apparatus, it is characterised in that：
In the IQ imbalances estimate,
&alpha; = r e a l ( &nu; &mu; )
&theta; = - 2 i m a g ( &nu; &mu; ) .
9. the unbalanced estimation module of inphase/orthogonal in a kind of ofdm system, it is characterised in that including With lower unit：
Frequency offset compensation element：For carrying out frequency deviation compensation to the time-domain signal for receiving；
Removal cyclic prefix unit：For removing Cyclic Prefix；
Frequency-domain transform unit：For two times upper neighbouring different frequency pilot signs to be transformed into frequency domain；
Subcarrier extraction unit：For extracting the son load that the frequency pilot sign takes according to system bandwidth Ripple；
ν/μ computing units：For to described two frequency pilot signs, obtaining the institute on each subcarrier Two reception signals of pilot signal are stated, the coupling of IQ imbalance parameters and channel is then removed, asked Take IQ imbalance estimates.
10. estimation module as claimed in claim 9, it is characterised in that also include：
ν/μ averaging units, for being averaged on sub-carriers to ν/μ.
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CN104717172A (en) * 2015-03-06 2015-06-17 东南大学 IQ imbalance compensation method and device in transmitter

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CN107682287A (en) * 2017-09-14 2018-02-09 上海无线通信研究中心 Detection method/system, computer-readable recording medium and the equipment of signal of communication
CN110471051A (en) * 2019-08-16 2019-11-19 广州大学 OFDM waveform object detection method, device and storage medium under a kind of multiple access
CN111541631A (en) * 2020-04-10 2020-08-14 清华大学 Channel estimation method and device based on IQ imbalance MIMO system

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