CN106911607B - The unbalanced estimation method of inphase/orthogonal and its module in a kind of ofdm system - Google Patents
The unbalanced estimation method of inphase/orthogonal and its module in a kind of ofdm system Download PDFInfo
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- CN106911607B CN106911607B CN201510975406.6A CN201510975406A CN106911607B CN 106911607 B CN106911607 B CN 106911607B CN 201510975406 A CN201510975406 A CN 201510975406A CN 106911607 B CN106911607 B CN 106911607B
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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
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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
- H04L27/2668—Details of algorithms
- H04L27/2673—Details of algorithms characterised by synchronisation parameters
- H04L27/2675—Pilot or known symbols
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/32—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
Abstract
The invention discloses the unbalanced estimation method of inphase/orthogonal and its modules in a kind of ofdm system.The estimation method is the following steps are included: S1: carrying out frequency deviation compensation to the time-domain signal received；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 occupies 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: IQ imbalance estimated value is sought in the coupling of removal IQ imbalance parameter and channel.Not only wide application, the timing requirements handled for receiver are low by the present invention；And meeting most of practical application scene demand, algorithm is simple, and calculation amount is small.
Description
Technical field
The present invention relates to one kind in OFDM (orthogonal frequency division multiplexing) system, to inphase/orthogonal (In-phase/
Quadrature-phase, referred to as IQ) the uneven method and its module estimated, belong to wireless communication technology field.
Background technique
In common ofdm communication system (such as 802.11a/g/n/ac series and LTE), in order to promote spectrum utilization
Efficiency has generallyd use high order modulation or MIMO technology.These complicated transmission plans require receiver that can obtain relatively
Higher signal-to-noise ratio (SNR).And transceiver is limited to production cost, it may be necessary to non-ideal using the device of more low price
IQ unbalance response will lead to receiving end signal-to-noise ratio decline, seriously affect receptivity.In order to promote receptivity, having must
To estimate IQ imbalance accurately to compensate to receiving end.
For the wide-band communication system based on OFDM technology, entire frequency band has been divided into multiple sub- loads by itself
Wave, therefore common IQ imbalance estimation method often carries out operation calculating using in frequency domain.Such as in ofdm system
The estimation of IQ imbalance, Broadcom Corp is in U.S. Patent application " IQ imbalance estimation using
It is based on symmetrical pilot configuration in broadcast signals " (Publication No. US2015103960A1), proposes using about DC
Then this statistic is supplied to channel estimation module and seeks channel and estimated by symmetrical pilot sub-carrier in pairs to obtain statistic
The result of channel estimation, is finally sent to IQ imbalance estimation module the coupling for being used to eliminate IQ imbalance and channel information by meter,
Obtain IQ imbalance estimates of parameters.It is required that the design of pilot signal be it is symmetrical about DC, this sets system pilot signal
The limitation of meter is larger.For example, in certain communication standards of UMTS LTE, since pilot tone is not disposed in symmetrical frequency, then this
Method is not applicable.Also, the patent application needs first to complete pilot channel estimation, then could estimate IQ imbalance, therefore right
The timing of specific implementation requires.Further more, the patent application assumes that adjacent sub-carrier channel is flat in channel estimation, this is false
If for lesser subcarrier spacing, such as LTE system (subcarrier spacing 15kHz) is more reasonable；And for there is larger son
For the ofdm system at carrier wave interval, such as 802.11a/g/n/ac system (subcarrier spacing 312.5kHz), then the hypothesis
It may not set up.
In order to remove dependence of the IQ imbalance algorithm for estimating for symmetrical pilot configuration, Ericsson is in notification number
In the Chinese invention patent " for estimating the unbalanced method and arrangement of IQ " of CN102057644B, propose using data symbol come
Portion of pilot symbol is substituted, that is, is constituted about the symmetrical pilot/data subcarrier pair of DC, to estimate IQ imbalance, main body
Thinking is similar with the patent application of above-mentioned company, Botong, needs the data symbol used carrying out channel estimation and demodulation,
It is then viewed as known symbol (being equivalent to pilot tone).This method has following shortcoming: needing first to complete data symbol demodulation, so
After could estimate IQ imbalance, therefore the timing of specific implementation is required, and complexity is higher；Channel on data symbol is estimated
Meter is generally generated by the channel estimation interpolation in pilot tone, itself causes IQ imbalance to be estimated containing IQ imbalance and interpolation error
Accuracy not as good as directly use symmetrical pilot signal；Data symbol demodulation can then directly result in IQ injustice in case of mistake
Weighing apparatus estimation error.
Ericsson " accords in another Chinese invention patent that notification number is CN102668483B for asymmetric pilot tone
Number IQ imbalance estimation " in, propose based on IQ imbalance be static parameter it is assumed that receive ofdm signal initial stage it is downward
Additional frequency shift (FS) is added when mixing, (this time-frequency spectrum shifts, no so that obtaining symmetrical pilot sub-carrier in baseband signal
Again centered on DC).Then the IQ imbalance algorithm for estimating based on symmetrical pilot tone is used, finally also needs to compensate additional frequency
Offset.After obtaining IQ imbalance estimated value, received using normal lower mixing, no longer progress IQ imbalance estimation.The party
Method has following shortcoming: needing additional using different lower frequency mixing methods, and in lower mixing at the initial stage for receiving ofdm signal
The frequency shift (FS) of addition depends on specific pilot design, and implementation complexity is high；Assuming that IQ imbalance is quiescent value, IQ cannot achieve
Unbalanced real-time estimation；Also by temperature, the time-varying factor such as voltage influences IQ imbalance in actual environment, therefore this method
Utility values must be discussed.
Summary of the invention
Primary technical problem to be solved by this invention is to provide in a kind of ofdm system that inphase/orthogonal is unbalanced to be estimated
Meter method.
Another technical problem to be solved by this invention is to provide in a kind of ofdm system that inphase/orthogonal is unbalanced to be estimated
Count module.
For achieving the above object, the present invention uses following technical solutions:
The unbalanced estimation method of inphase/orthogonal in a kind of ofdm system, comprising the following steps:
S1: frequency deviation compensation is carried out to the time-domain signal received；
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 occupies is extracted according to system bandwidth；
S4: for described two frequency pilot signs, the reception signal of described two pilot signals on each subcarrier is obtained；
S5: IQ imbalance estimated value is sought in the coupling of removal IQ imbalance parameter and channel.
Wherein more preferably, the coupling that IQ imbalance parameter and channel are removed in step S5, is on a subcarrier
Seek the ratio of IQ imbalance parameter
Wherein more preferably, it is acquired respectively at least two subcarriers in the subcarrierWith described at least two
On subcarrierAverage value seek IQ imbalance estimated value.
Wherein more preferably, it is acquired respectively on each subcarrier in the subcarrierOn each subcarrier
'sAverage value seek IQ imbalance estimated value.
Wherein more preferably, further comprising the steps of: upper neighbouring different frequency pilot signs of described two times, before referring to two
Leading code symbol STF and LTF.
Wherein more preferably, upper neighbouring different frequency pilot signs of described two times, refer to that two on same carrier wave are leading
Code sign STF and LTF.
The unbalanced estimation module of inphase/orthogonal in a kind of ofdm system, comprising:
Frequency offset compensation element: for carrying out frequency deviation compensation to the time-domain signal received；
Remove cyclic prefix unit: for removing cyclic prefix；
Frequency-domain transform unit: for two times upper neighbouring different frequency pilot signs to be transformed to frequency domain；
Subcarrier extraction unit: for extracting the subcarrier that the frequency pilot sign occupies according to system bandwidth；And
ν/μ computing unit: for obtaining described two pilot signals on each subcarrier to described two frequency pilot signs
Reception signal, then remove IQ imbalance parameter and channel coupling, seek IQ imbalance estimated value.
Wherein more preferably, the estimation module further includes ν/μ averaging unit, for being averaged on sub-carriers to ν/μ.
Compared with prior art, the unbalanced estimation method of inphase/orthogonal provided by the present invention and its module have
Following advantage:
1. avoiding the dependence in conventional method for symmetrical pilot configuration, but led using two times upper neighbouring difference
Frequency symbol, application surface are wider.
2. low for the timing requirements of receiver processing without relying on channel estimation and data demodulation.
3. meeting most of practical application scene demand for there is the scene of frequency-selective channel to be applicable in.
4. algorithm is simple, calculation amount is small, it is easy to accomplish.
Detailed description of the invention
Fig. 1 is the flow diagram of IQ imbalance estimation method in ofdm system provided by the present invention；
Fig. 2 is the simulation result of IQ imbalance parameter alpha estimation；
Fig. 3 is the simulation result of IQ imbalance parameter θ estimation；
Fig. 4 is the structural block diagram of IQ imbalance estimation module in ofdm system provided by the present invention.
Specific embodiment
Detailed specific description is carried out to technology contents of the invention in the following with reference to the drawings and specific embodiments.
Present invention assumes that the two pilot signals are same there are time upper two neighbouring different pilot tones in ofdm system
Channel on a subcarrier is flat.The hypothesis is generally set up in common ofdm communication system.For example, (1)
STF/LTF in 802.11a/g/n/ac system, is separated by 8us on the time, be used for LAN environment, and time correlation degree is very high；(2)
Two column DMRS signals in LTE system on PUSCH are separated by 0.5ms containing different cyclic shifts on the time, for being less than
When the common scene of 120km/h speed per hour, time correlation degree is higher.
It is provided by the present invention to illustrate by taking the IQ imbalance estimation procedure in 802.11a/g/n/ac system as an example below
The unbalanced estimation method of inphase/orthogonal in ofdm system.In 802.11a/g/n/ac system, 2 in lead code are utilized
STF (short training field, short training sequence) and 2 LTF (1ong training field, long training sequence)
Come estimate IQ imbalance, processing block diagram it is as shown in Figure 1.
In IQ imbalance appraisal procedure provided by the present invention, it is assumed that α is that the gain of IQ branch is uneven, and θ is IQ branch
The unbalance in phase on road.Defined variable μ, ν is as follows:
It is easy to get, if without IQ imbalance, μ=1, ν=0.
As shown in Figure 1, this method includes the following steps；
S1: frequency deviation compensation is carried out to the time-domain signal received.
For frequency deviation, need to be estimated in advance and compensated.The step can be realized using the prior art, not gone to live in the household of one's in-laws on getting married herein
It states.
S2: after removal cyclic prefix, two times upper neighbouring different frequency pilot signs (time index is respectively n, m) are become
Change to frequency domain.
Specifically, being exactly to carry out FFT the two frequency pilot signs transform to frequency domain by STF/LTF.
For the reception signal in ofdm system containing IQ imbalance and frequency-selective channel, due to the unbalanced influence of IQ, when
It is s that domain, which receives signal,d=μ s+ ν s*.Wherein s is without the unbalanced original time domain signal of IQ, s*Indicate the conjugation of s, sdFor containing
There is the unbalanced distortion time-domain signal of IQ.
By FFT transform to frequency domain, frequency pilot sign is obtained in the reception signal S of time domaind=μ S+ ν Fconj (FHS)=μ S
+νZ.To simplify expression, Z=Fconj (F is defined in formulaHS).Since S is known pilot, then Z can be precalculated to subtract
Few real-time calculation amount.
S3: the subcarrier that frequency pilot sign occupies is extracted according to system bandwidth.
It is assumed herein that the number of sub carrier wave that the reception signal specifically occupies is Nsubc.The step can use existing skill
Art realizes that this will not be repeated here.It should be noted that receiving the number of sub carrier wave Nsubc that signal occupies is different from sub-carrier number N,
In general Nsubc < N, Nsubc are to occupy subcarrier, can be extracted and calculate IQ imbalance.In general, Nsubc=48 (son
Carrier bandwidths 80MHz)；Nsubc=24 (subcarrier bandwidth 40MHz)；Nsubc=12 (subcarrier bandwidth 20MHz).N is FFT
Size generally comprises protection sideband.
S4: for two frequency pilot signs, the reception signal of two pilot signals on each subcarrier is obtained.
Using the S and Z of acquisition, for each frequency pilot sign, a pair of of linear equation in two unknowns group is constituted on each subcarrier.
In view of the influence of frequency-selective channel, receiving signal can be expressed as Sd2=H (μ S+ ν Z).H is passed through by each subcarrier
The channel gone through.Wherein, S and Z can be prestored in advance, be obtained by reading, to construct linear equation in two unknowns group；It can also count in real time
It calculates and obtains S and Z.
Two times upper neighbouring different frequency pilot signs (time index is respectively n, m), that is, the two are leading by STF/LTF
Code sign can be considered flat in the same subcarrier k upper signal channel, i.e. Hk,n=Hk,m.Therefore, two on k-th of subcarrier
The reception signal of pilot signal (time index is respectively n, m) are as follows:
In known Sd2,k,n,Sd2,k,m,Sk,n,Sk,m,Zk,n,Zk,mIn the case where, it is apparent from μ Hk,n,νHk,nIt can be by solving binary
The mode of linear function acquires.From equation group as it can be seen that IQ imbalance with channel couples together, can not separate.
S5: IQ imbalance estimated value is sought in the coupling of removal IQ imbalance parameter and channel.
In order to remove the coupling of IQ imbalance parameter and channel, it can use simplified algorithm and seekTherefore, of the invention
The upper two neighbouring different frequency pilot sign STF/LTF of time in ofdm system are chosen, IQ injustice is sought on the same subcarrier k
The ratio for the parameter that weighsCounteract channel Hk,nInfluence, realize IQ imbalance parameter and channel decoupling.
Although it has been observed that μ Hk,n,νHk,nIt can be acquired by way of solving linear equation in two unknowns, but in order to seek IQ not
Balance parameters α and θ do not need to solve above-mentioned linear equation in two unknowns, and the present invention uses following simplification method:
| α | < < 1, | θ | (it is greater than the unbalanced typical value range of IQ, bibliography under the hypothesis of≤5degree
《Widely linear block-diagonalization type precoding in massive MIMO systems
With IQ imbalance ", ICC 2015, p3392-3397, Jun 2015), it is available such as lower aprons:
Therefore it only needs to calculateIt can obtain and easily seek IQ imbalance
Parameter alpha, θ.
In addition, this estimation method further comprises: right to improve estimated accuracyIt is average to do subcarrier, to promote α, θ's
Estimated accuracy.This is because IQ imbalance parameter be it is slowly varying, can be by asking over the plurality of subcarriersAnd it is put down
Improve α, the accuracy of θ estimation.
Specifically, being on each subcarrier, to receive signal based on STF/LTF and acquireAgain by each subcarrier
OnSummation carries out arithmetic average.It obtainsMean value recycles formula (4) and (5) that α, θ valuation is calculated, to obtain
To IQ imbalance estimated value.
Be apparent from, due to when pilot tones partially different for two influence on sub-carrierk unanimously, this method for when it is partially unwise
Sense.Frequency deviation then needs to be estimated and compensated in advance.
Present invention could apply in ofdm system, realize the estimation for IQ imbalance parameter, so as to receiving end for
IQ imbalance compensates.
Estimation method provided by the present invention completely avoids the dependence in conventional method for symmetrical pilot configuration, utilizes
It is reasonable to simplify approximation, seek IQ imbalance parameter alpha, θ.It is not necessarily to channel estimation and data demodulation in treatment process, therefore realizes
On to receiver processing timing requirements it is low.This estimation method for containing frequency-selective channel and when inclined scene, have in performance
There is robustness.Algorithm operation quantity is small, is especially advantageous for realizing.
The processing branch of estimation method provided by the present invention is after frequency deviation compensation, and independently of channel estimation, channel is equal
Weighing apparatus, the processing modules such as data demodulation.It is either applied on receiver or test equipment, when this feature can optimize reception
Sequence.
By fixed-point simulation, it is quasi- to demonstrate estimation of the estimation method provided by the present invention in typical α, θ value range
True property.It is α that wherein linear value α, which is converted into the formula of dB expression,dB=10*log10 (α+1).According to 802.11a/g/n/ in emulation
Ac standardizes the test definition for modulating characteristic, and the time for using 20 frames (frame) averagely obtains accurately measurement knot
Fruit.
Emulation 1, mainly research are at different α, θ value (range is greater than the unbalanced typical value range of IQ), algorithm
Accuracy 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 alpha, the simulation result diagram of θ estimation is given below.
As shown in Fig. 2, in the case where given θ (value be [- 5:5] corresponding 11 curves), α [- 0.3:0.02:
0.3] it is accurate to estimate within the scope of dB.What asterisk marked is the reference value for comparison in figure, that is, the α value set.
As shown in figure 3, in the case where given α (value be [- 0.3:0.02:0.3] dB corresponding 31 curves), θ [-
5:5] the interior estimation of degree range is accurately.What asterisk marked is the reference value for comparison in figure, that is, the θ value set.
Emulation 2, mainly research is at typical α, θ value, the accuracy of algorithm.
Simulation parameter setting is as follows:
The mean square error of simulation result is as shown in the table:
It can see according to above-mentioned simulation result, inphase/orthogonal is unbalanced in ofdm system provided by the present invention estimates
Meter method accuracy is high, meets actual demand.
Front describes the principle of the present invention and embodiment by taking 802.11a/g/n/ac system as an example.But this is specific
Embodiment should be considered as illustrative and not restrictive, and the present invention should not be considered limited to above-mentioned specific embodiment.Specific
In ofdm system, specific implementation of the invention can be changed accordingly.For example, can use PUSCH in LTE system
On two column DMRS signals carry out frequency-domain transform as two times of the invention upper neighbouring different frequency pilot signs, then build
It is vertical to receive signal set of equations.Pass through the ratio for the IQ imbalance parameter sought on subcarrierIQ imbalance is acquired to estimate
Count α, θ.Similar, it can also be by rightIt is averaging on sub-carriers, improves precision.
IQ imbalance estimation method provided by the present invention suitable for ofdm system, has used on the same subcarrier
Two different pilot signals change over time lesser feature using neighbouring OFDM symbol upper signal channel, the influence of channel are offset.
It is approximate by reasonably simplifying, calculation amount is greatly reduced, finally by simulation results show this method can accurately be estimated
IQ is uneven.
The major advantage of above-mentioned estimation method are as follows: do not require about the symmetrical pilot configuration of DC, independent of channel estimation
And data demodulation, there is robustness to frequency-selective channel, algorithm for estimating calculation amount is small to be easily achieved.
It is appreciated that the present invention also provides a kind of IQ imbalance estimation module, it is uneven for realizing aforementioned OFDM system IQ
Each step in the estimation method that weighs, to estimate IQ imbalance estimated value.
Specifically, IQ imbalance estimation module includes with lower unit with reference to Fig. 1 and Fig. 4:
Frequency offset compensation element: for carrying out frequency deviation compensation to the time-domain signal received；
Remove cyclic prefix unit: for removing cyclic prefix；
Frequency-domain transform unit: for two times upper neighbouring different frequency pilot signs to be transformed to frequency domain；
Subcarrier extraction unit: for extracting the subcarrier that the frequency pilot sign occupies according to system bandwidth；
ν/μ computing unit: for obtaining described two pilot signals on each subcarrier to described two frequency pilot signs
Reception signal, then remove IQ imbalance parameter and channel coupling, seek IQ imbalance estimated value.
To improve precision, ν/μ averaging unit can also be increased, for being averaged on sub-carriers to ν/μ.
The unbalanced estimation method of inphase/orthogonal and its module in ofdm system provided by the present invention are carried out above
Detailed description.For those of ordinary skill in the art, it is done under the premise of without departing substantially from true spirit
Any obvious change, will all constitute the infringement weighed to the invention patent, corresponding legal liabilities will be undertaken.
Claims (10)
1. the unbalanced estimation method of inphase/orthogonal in a kind of ofdm system, it is characterised in that the following steps are included:
S1: frequency deviation compensation is carried out to the time-domain signal received；
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 occupies is extracted according to system bandwidth；
S4: for described two frequency pilot signs, the reception signal of described two pilot signals on each subcarrier is obtained；
S5: using the coupling of following formula removal IQ imbalance parameter and channel, seeking IQ imbalance estimated value,
WhereinIt is the ratio that IQ imbalance parameter is sought on a subcarrier, α is the gain imbalance ginseng of IQ branch
Number, θ are the unbalance in phase parameter of IQ branch.
2. the unbalanced estimation method of inphase/orthogonal in ofdm system as described in claim 1, it is characterised in that:
In step S2, upper neighbouring different frequency pilot signs of described two times are flat in the same subcarrier upper signal channel.
3. the unbalanced estimation method of inphase/orthogonal in ofdm system as claimed in claim 2, it is characterised in that further include with
Lower step:
It is acquired respectively at least two subcarriers in the subcarrier
On at least two subcarrierAverage value seek IQ imbalance estimated value.
4. the unbalanced estimation method of inphase/orthogonal in ofdm system as claimed in claim 2, it is characterised in that further include with
Lower step:
It is acquired respectively on each subcarrier in the subcarrier
On each subcarrierAverage value seek IQ imbalance estimated value.
5. the unbalanced estimation method of inphase/orthogonal in ofdm system as claimed in claim 2 or claim 3, it is characterised in that:
Described two times, upper neighbouring different frequency pilot signs referred to two leading code sign STF and LTF.
6. the unbalanced estimation method of inphase/orthogonal in ofdm system as claimed in claim 5, it is characterised in that:
Described two times, upper neighbouring different frequency pilot signs referred to two leading code sign STF and LTF on same carrier wave.
7. the unbalanced estimation method of inphase/orthogonal in ofdm system as claimed in claim 2 or claim 3, it is characterised in that:
Upper neighbouring different frequency pilot signs of described two times refer to two column DMRS signals in LTE system on PUSCH.
8. the unbalanced estimation method of inphase/orthogonal in the ofdm system as described in any one of claims 1 to 3, special
Sign is:
In the IQ imbalance estimated value, | α | < < 1, | θ |≤5degree
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 received；
Remove cyclic prefix unit: for removing cyclic prefix；
Frequency-domain transform unit: for two times upper neighbouring different frequency pilot signs to be transformed to frequency domain；
Subcarrier extraction unit: for extracting the subcarrier that the frequency pilot sign occupies according to system bandwidth；
Computing unit: for obtaining connecing for described two pilot signals on each subcarrier to described two frequency pilot signs
The collection of letters number seeks IQ imbalance estimated value then using the coupling of following formula removal IQ imbalance parameter and channel,
WhereinIt is the ratio that IQ imbalance parameter is sought on a subcarrier, α is the gain imbalance ginseng of IQ branch
Number, θ are the unbalance in phase parameter of IQ branch.
10. estimation module as claimed in claim 9, it is characterised in that further include:
Averaging unit, for pairIt is averaged on sub-carriers.
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| CN110471051B (en) * | 2019-08-16 | 2021-08-13 | 广州大学 | OFDM waveform target detection method and device under multi-user access and storage medium |
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| EP2109273A1 (en) * | 2008-04-11 | 2009-10-14 | Telefonaktiebolaget LM Ericsson (PUBL) | Methods and arrangements for estimating IQ-imbalance |
| US7649832B2 (en) * | 2006-07-05 | 2010-01-19 | Kabushiki Kaisha Toshiba | Wireless communication method using OFDM, OFDM receiving method and apparatus thereof |
| CN103152308A (en) * | 2013-03-04 | 2013-06-12 | 北京科技大学 | Joint estimation method of frequency offset, DC (Direct Current) and imbalance of orthogonal frequency division multiplexing system |
| CN104468430A (en) * | 2014-12-23 | 2015-03-25 | 南京理工大学 | Channel parameter evaluation method for IQ imbalance type OFDM system receiver |
| CN104717172A (en) * | 2015-03-06 | 2015-06-17 | 东南大学 | IQ imbalance compensation method and device in transmitter |
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|---|---|---|---|---|
| US7649832B2 (en) * | 2006-07-05 | 2010-01-19 | Kabushiki Kaisha Toshiba | Wireless communication method using OFDM, OFDM receiving method and apparatus thereof |
| EP2109273A1 (en) * | 2008-04-11 | 2009-10-14 | Telefonaktiebolaget LM Ericsson (PUBL) | Methods and arrangements for estimating IQ-imbalance |
| CN103152308A (en) * | 2013-03-04 | 2013-06-12 | 北京科技大学 | Joint estimation method of frequency offset, DC (Direct Current) and imbalance of orthogonal frequency division multiplexing system |
| CN104468430A (en) * | 2014-12-23 | 2015-03-25 | 南京理工大学 | Channel parameter evaluation method for IQ imbalance type OFDM system receiver |
| CN104717172A (en) * | 2015-03-06 | 2015-06-17 | 东南大学 | IQ imbalance compensation method and device in transmitter |
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