CN113132028A

CN113132028A - Originating IQ correction method

Info

Publication number: CN113132028A
Application number: CN202110447884.5A
Authority: CN
Inventors: 马雅男; 邹建; 李振川
Original assignee: Chengdu Jovian Technology Exploitation Co ltd
Current assignee: Chengdu Jovian Technology Exploitation Co ltd
Priority date: 2021-04-25
Filing date: 2021-04-25
Publication date: 2021-07-16
Anticipated expiration: 2041-04-25
Also published as: CN113132028B

Abstract

The invention discloses an originating IQ correction method, which comprises the following steps: s1, the transmitting end respectively sends a plurality of groups of signals TX, and the plurality of groups of signals TX enter a receiving channel for processing after self-multiplication to respectively obtain a plurality of groups of signals RX; s2, after cross-correlation is carried out between multiple groups of signals RX and multiple groups of sinusoidal signals generated at the receiving end, a signal corresponding to the maximum value of a cross-correlation curve is taken for delay phase estimation and the like; the invention can correct IQ imbalance of the signal at the transmitting end, simultaneously avoids the influence of IQ imbalance at the receiving end on the system, improves the signal-to-noise ratio of the signal at the transmitting end, has high realizability, can effectively reduce the influence of mirror image components, improves the performance of the system, and has strong practical value and the like.

Description

Originating IQ correction method

Technical Field

The present invention relates to the field of communications, and more particularly, to an originating IQ correction method.

Background

With the development of wireless communication, higher and higher requirements are put on miniaturization, easy integration, and the like of devices [1 ]. The development of industry is severely restricted by the traditional super-extrapolation structure transceiver at present, and the novel zero intermediate frequency transceiver is gradually paid attention to by people to become a hotspot of research in the years with the advantages of simple structure, easy integration, low power consumption and small volume [ 2-4 ]. However, in the practical application process, due to the limitation of device processes, the devices such as filters, amplifiers, mixers and the like on the in-phase branch and the quadrature branch cannot be completely consistent, and the two outputs of the local oscillator signals cannot be completely orthogonal, so that the output of the I-path response signal and the Q-path response signal is unbalanced, which means that the signal spectrum has image components, and the image signals reach a certain power, which causes serious distortion of the main signal, further reduces the dynamic range of the system, and deteriorates the overall performance of the system [5 ]. Therefore, how to eliminate the IQ imbalance phenomenon is a hot problem of current research, and has certain practical significance.

Currently, there are two types of analog domain and digital domain for IQ imbalance correction. The analog domain improves the consistency of the devices by optimizing the circuit structure and changing the layout mode of the devices, thereby reducing the influence of IQ imbalance [6], but the damage caused by IQ imbalance still cannot be eliminated by utilizing the mode. Subsequently, document [7] reports a compensation mode of a digital domain, and a mode of inserting a training sequence into a signal is utilized to estimate IQ amplitude and phase imbalance parameters for compensation. In recent years, people introduce concepts such as a channel estimation algorithm, a sparse matrix algorithm, a simulated annealing algorithm and the like based on a least square method into an IQ correction method to obtain favorable performance [ 8-10 ], but due to the complex structure and high implementation difficulty, the IQ correction method cannot be used in practice for commercial use at present, so that the search for a simple and easy-to-implement algorithm is an urgent need at present.

The classic structure of the zero-if transmitter is shown in fig. 1, the generated baseband signal is split into an I path and a Q path, which enter an upper path and a lower path respectively, the upper path signal is converted into an analog signal by a DAC and then multiplied by cos ω t, the lower path signal is multiplied by a-sin ω t carrier wave after passing through a DAC module, where ω ═ 2 π f, f represents the carrier frequency, and through this mixing process, the transmitter up-converts the baseband signal with a center frequency of zero to the center frequency point of the radio frequency signal. Under an ideal model, the amplitude-frequency and phase-frequency characteristics of the I path and the Q path should be completely consistent, the local oscillator amplitudes of the Q path and the I path are the same, and the phase difference is 90 degrees. However, the above conditions are very difficult to satisfy for process reasons, and therefore, there is an IQ imbalance phenomenon, and a model at this time is shown in fig. 2.

In the figure:

wherein x is_I(t) and x_Q(t) represents the frequency conversion output of the I path and the Q path, the I path and the Q path represent the input signals of the I path and the Q path, the I path and the Q path_DCAnd Q_DCCharacterizing the DC component, ω, of the paths I and Q_LO＝2πf_LO，f_LORepresenting the carrier frequency, g represents the amplitude deviation of the I and Q responses,

the phase deviation of the I-path response and the Q-path response is reflected. Combining the above formulas to obtain an output result as follows:

therefore, according to the above formula, the equivalent model of the originating IQ imbalance is shown in fig. 3.

For a transmitting-end system, IQ imbalance is unavoidable, and causes the phenomenon are various, including IQ imbalance caused by process problems of a plurality of devices such as a modulator, a local oscillator, a filter, a DAC and the like. The most remarkable characteristic of this phenomenon is that image frequency components are generated for the original signal, thereby affecting the signal-to-noise ratio of the originating signal. Therefore, how to reduce the influence of IQ imbalance and improve the system performance of the transmitter is a current research hotspot and has important practical significance.

The existing references:

[1] the development and application of data communication microsatellite constellation systems [ J ] spacecraft engineering, 2011, 2: 66.

[2] chiffon zero intermediate frequency transmitter design and implementation [ J ] electronics, 2014, 27 (3): 73.

[3]SLUK A,WALSH D.Transcutaneous electrical nerve stimulation:basic science mechanisms and clinical effectiveness[J].J Pain,2003,4(3)：109.

[4]PECKHAM P H,KNUTSON J S.Functional electrical stimulation for neuromuscular applications[J].Annu Revi Biomed Engineer,2005,7(7)：327.

[5]EVERETT E,SAHAI A,SABHARWAL A,et al.Passiveself-interference suppression for full-duplex infrastructure nodes[J].IEEE Transactions on Wireless Communications,2014,13(2)：680.

[6] roc, feiyanchun, analysis and optimization design of sideband and local oscillator leakage of direct orthogonal up-conversion [ J ] war, 2004, 25 (6): 712.

[7]GU C F,LAW C L,WU W.Time domain IQ imbalance compensation for wideband wireless systems[J].IEEE Communications Letters,2010,14(6):539.

[8]WANG J,YU H,WU Y,et al.Pilot optimization and power allocation for OFDM-based full-duplex relay networks with IQ-imbalances[J].IEEE Access,2017,5:24344.

[9]SHU F,ZHAO J H,YOU X H,et al.An efficient sparse channel estimator combining time-domain LS and iterative shrinkage for OFDM systems with IQ-imbalances[J].Science China Information Sciences,2012,55(11):2604.

[10] huang jiajun, teng lai, zhang houjie, wang chunhui, brave naughty I/Q imbalance correction based on simulated annealing algorithm [ J ]. university of zhejiang, 2018, 52 (11): 2218.

disclosure of Invention

The invention aims to overcome the defects of the prior art and provides an IQ correction method for an originating signal, which can correct IQ imbalance of the originating signal, avoid the influence of IQ imbalance of a receiving end on a system, improve the signal-to-noise ratio of the originating signal, has high realizability, can effectively reduce the influence of a mirror component, improve the performance of the system, and has strong practical value and the like.

The purpose of the invention is realized by the following scheme:

an outbound IQ correction method, comprising:

s1, the transmitting end respectively sends a plurality of groups of signals TX, and the plurality of groups of signals TX enter a receiving channel for processing after self-multiplication to respectively obtain a plurality of groups of signals RX;

s2, cross-correlating the multiple sets of signals RX with the multiple sets of sinusoidal signals generated at the receiving end, and then performing delay phase estimation by taking the signal corresponding to the maximum value of the cross-correlation curve.

Further, in step S2, the method further includes taking the signal corresponding to the minimum value of the cross-correlation curve to perform I-path and Q-path DC error estimation, gain imbalance parameter estimation, and phase imbalance parameter estimation.

Further, in step S1, the originating end sends three sets of signals TX1, TX2, TX3, respectively, which are respectively expressed as:

wherein t represents time, I (t) represents I-path sending signal of the sending end, Q (t) represents Q-path sending signal of the sending end, omega₀Representing the angular frequency of the transmitted signal.

Further, in step S2, the sets of sinusoidal signals generated at the receiving end include four sets of sinusoidal signals, which are denoted as Rx _1(i), Rx _2(i), Rx _3(i), and Rx _4(i), respectively, and each set of sinusoidal signals includes N signals with the same frequency and different initial phases, that is:

wherein N represents a defined positive integer, and i represents an integer value selected within [0, N-1 ].

Further, in step S2, after the three groups of signals TX1, TX2, and TX3 are self-multiplied and enter the receiving channel for processing, three groups of signals RX1, RX2, and RX3 are obtained, and then the three groups of signals RX1, RX2, and RX3 are cross-correlated with the four groups of sinusoidal signals RX _1(i), RX _2(i), RX _3(i), and RX _4(i) generated by the receiving end to obtain maximum values, so as to obtain N1, N2, N3, and N4, respectively, that is:

N1＝max{corr(Rx1,Rx_1(i))|_{i＝0,1,2...N-1}}

N2＝max{corr(Rx2,Rx_2(i))|_{i＝0,1,2...N-1}}

N3＝max{corr(Rx3,Rx_3(i))|_{i＝0,1,2...N-1}}

N4＝max{corr(Rx3,Rx_4(i))|_{i＝0,1,2...N-1}}

the three sets of signals R1, R2, R3 corresponding to the maximum values are:

where corr is the identifier of the cross-correlation.

Further, in step S2, the range of the I-path DC offset [ -g _ I [ ]_max，+g_I_max]Divide it intoIs N_I+1, the originating transmission signal TX is expressed as:

wherein i ═ 0,1, … N_I]Received N_I+1 groups of signals, each correlated with R1 with the smallest corresponding delta_I＝E_I(k₀) Estimate of the I-way DC error:

wherein E is_I(i) Indicating the value of DC offset of the originating I-path signal during measurement, N_IIndicating the set equipartition value, I (I) indicating the I signal output of the originating terminal, Q (I) indicating the Q signal output of the originating terminal, k₀Representing the value of i, delta, corresponding to the minimum value found after cross-correlation_ITo obtain an I-way DC error estimate.

Further, in step S2, the Q-way DC offset is set to range [ -g _ Q [ ]_max，+g_Q_max]Divide it into N_Q+1, the originating transmission signal TX is expressed as:

wherein i ═ 0,1, … N_Q]Is connected toReceived N_I+1 groups of signals, each correlated with R2 with the smallest corresponding delta_Q＝E_Q(k₁) For the Q-way DC error estimate:

wherein E is_Q(i) Representing the DC compensation value, N, of the Q-path signal at the measurement time_QDenotes the set equivalence value, k1 denotes the value of i corresponding to the minimum value found after cross-correlation, δ_QTo obtain a Q-path DC error estimate.

Further, let the range of the gain imbalance parameter [ -g ]_max，+g_max]Divide it into N_g+1, the transmission signal TX is expressed as:

wherein i ═ 1, … N_g+1]Received N_g+1 groups of signals are respectively cross-correlated with R2 and R3, and g corresponding to the averaged minimum value of the correlation is calculated_t＝E_g(k₂) For gain imbalance parameter estimation:

wherein E is_g(i) Represents the gain imbalance estimate, N, used in the test_gRepresenting the set equivalence value, k2 representing the minimum value i found after cross-correlation, and then averaging; g_tTo obtain an estimate of the gain imbalance parameter.

Further, let the parameter range of the phase imbalance

Divide it into

And if yes, the sending end sending signal TX is expressed as:

wherein

Received (a)

The group signals are respectively cross-correlated with R2 and R3, and the correlation minimum values are averaged to correspond to

For phase imbalance parameter estimation:

wherein the content of the first and second substances,

representing the I, Q two-way phase imbalance estimate used for the test,

indicating the set equipartition value, k₃Representing the minimum value i found after cross-correlation, and then averaging;

to obtain the estimated value of the phase imbalance parameter.

Further, in step S1, the multiple sets of signals TX after self-multiplication enter the receiving channel for processing, including filtering and amplifying.

The invention has the beneficial effects that:

the method is simple, does not need to add additional devices or equipment, can be completed in the system initialization process only by the method, and has high realizability;

the method can effectively reduce the influence of the image component and improve the performance of the system;

the method of the invention can avoid the influence of IQ imbalance of the receiver, thereby having strong practical value.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a block diagram of a classical transmitter;

FIG. 2 is a schematic diagram of an originating IQ imbalance;

FIG. 3 is a diagram of an equivalent model of an originating IQ imbalance;

FIG. 4 is a block diagram of an originating IQ correction scheme;

FIG. 5 is a diagram of a transmit-end cosine signal spectrum;

FIG. 6 is a frequency spectrum diagram of the transmit-end cosine signal after up-conversion;

FIG. 7 is a graph of the spectrum of a self-multiplied originating signal;

FIG. 8 is a graph of the spectrum after receive filtering;

FIG. 9 is a cross-correlation plot of a received signal with a receive cos signal;

FIG. 10 is a graph of the spectrum of an originating sinusoidal signal;

FIG. 11 is a frequency spectrum diagram of an up-converted transmit-end cosine signal;

FIG. 12 is a graph of the spectrum of a self-multiplied originating signal;

FIG. 13 is a graph of the spectrum after receive filtering;

fig. 14 is a graph of the cross-correlation of a received signal with a receive sin signal;

FIG. 15 is a graph of the spectrum of an originating single-tone signal;

fig. 16 is a graph of the frequency spectrum of an up-converted originating single-tone signal;

FIG. 17 is a graph of the spectrum of a self-multiplied originating single-tone signal;

FIG. 18 is a graph of the spectrum after receive filtering;

FIG. 19 is a graph of cross-correlation of a received signal with a receive 2cos signal;

fig. 20 is a graph of the cross-correlation of a received signal with a received 2sin signal;

FIG. 21 is a diagram of a transmit-end cosine signal spectrum;

FIG. 22 is a graph of the spectrum of a self-multiplied originating signal;

FIG. 23 is a graph of the spectrum of a self-multiplied originating signal;

fig. 24 is a graph of the spectrum after receive filtering;

fig. 25 is a graph of cross-correlation of 20 sets of received signals with a receive cos signal;

FIG. 26 is a diagram of a transmit-end cosine signal spectrum;

FIG. 27 is a frequency spectrum diagram of an originating sinusoidal signal after up-conversion;

FIG. 28 is a graph of the spectrum of a self-multiplied originating signal;

fig. 29 is a graph of the spectrum after receive filtering;

fig. 30 is a cross-correlation plot of 20 sets of received signals with a receive sin signal;

FIG. 31 is a diagram of the spectrum of an originating single-tone signal;

fig. 32 is a graph of the frequency spectrum of an up-converted originating single-tone signal;

FIG. 33 is a graph of the spectrum of the self-multiplied originating signal;

fig. 34 is a graph of the spectrum after receive filtering;

fig. 35 is a graph of cross-correlation of 20 sets of received signals with a receive 2cos signal;

FIG. 36 is a diagram of the spectrum of an originating single-tone signal;

fig. 37 is a graph of the frequency spectrum of an up-converted originating single-tone signal;

FIG. 38 is a graph of the spectrum of a self-multiplied originating signal;

FIG. 39 is a graph of the spectrum after receive filtering;

fig. 40 is a graph of cross-correlation of 20 sets of received signals with a receive 2cos signal.

Detailed Description

All features disclosed in all embodiments in this specification, or all methods or process steps implicitly disclosed, may be combined and/or expanded, or substituted, in any way, except for mutually exclusive features and/or steps.

In order to make the thought and the technical scheme improvement thought of the invention more understandable for those skilled in the art, the principle of the invention is explained in detail as follows:

first, according to fig. 3, the TX signal is output as follows through the IQ imbalance procedure of the transmitter:

the TX end does not send a signal directly, but performs self-multiplication to obtain:

the self-multiplied signals are transmitted through the antenna, the RX end receives the signals, and then the signals are directly received by the PD after filtering and amplification, so that the effects of down-conversion, filtering and the like of the RX end are avoided, therefore, the influences of two paths of PD errors, local oscillator leakage and filter amplitude-frequency response difference of the RX end are removed, the received signals cannot be influenced, and the signals received by the receiving end deteriorate the influence of IQ imbalance from the transmitting end. The invention finds that when the receiving end RX receives a signal consistent with the transmitted signal during B2B transmission, according to equation (3-2):

wherein ω is₀And substituting the frequency points defined in the transmission bandwidth range into a formula to obtain:

from the above formula, wherein

The information on the frequency point is

Where g represents the magnitude deviation of the I and Q responses,

reflects the phase deviation of the I path and the Q path_DCAnd Q_DCAnd characterizing the direct current components of the I path and the Q path. Then, based on the above analysis, the present invention finds that when the IQ-two paths are fully balanced,

the bins should not carry information and therefore their objective function should be zero. Due to the fact that

The number of imbalance parameters involved is three, and it is not easy to find the best value of self-consistency, so here the invention only finds the best δ_ITo stand againstXiao I_DCThe influence of (c). By setting different delta at the originating end_ISending the values into the transmitter structure shown in fig. 4, performing fourier transform on the signals at the receiving end, and recording the signals in the frequency spectrum

The magnitude of the frequency bins. Finding the minimum of the amplitude after polling, which corresponds to delta_IIs marked as I_DCIs measured.

The invention then sends another set of data:

substituting into the formula, we get:

from the above formula, wherein

The information on the frequency point is

Then, based on analysis, the present invention finds that when the IQ-two paths are fully balanced,

the bins should not carry information and therefore their objective function should also be zero. Due to the fact that

The number of imbalance parameters involved is three, and it is not easy to find the best value of self-consistency, so here the invention only finds the best δ_QTo cancel Q_DCThe influence of (c). By setting different delta at the originating end_QSending the values into the transmitter structure shown in fig. 4, performing fourier transform on the signals at the receiving end, and recording the signals in the frequency spectrum

The magnitude of the frequency bins. Finding the minimum of the amplitude after polling, which corresponds to delta_QIs recorded as Q_DCIs measured.

The invention then sends a signal:

substituting into the formula, we get:

from the above formula, wherein

The information on the frequency point is

the bins should not carry information and therefore their objective function should also be zero. Therefore here the invention seeks to find the best g_tAnd

to counteract g and

the influence of (c). By setting different g at the transmitting end_tAnd

sending the values into the transmitter structure shown in fig. 4, performing fourier transform on the signals at the receiving end, and recording the signals in the frequency spectrum

The magnitude of the frequency bins. Finding the minimum of amplitude after polling, which corresponds to g_tThe estimated parameter noted g is then used to estimate the parameters,

is marked as

Is measured.

Based on the above principle analysis, the specific embodiment of the present invention includes the following steps:

according to the description of the transmitting IQ correction method, verification is performed by matlab simulation, wherein the main parameters are shown in the following table 1, and the simulation process of the system comprises delay error search, I-path DC offset estimation, Q-path DC offset estimation, gain imbalance parameter estimation and phase imbalance parameter estimation.

TABLE 1 reference table for setting originating correction parameters

The simulation verification is carried out by utilizing the parameters, and the method comprises the following steps:

1. generating a signal:

the frequency spectrum is shown in fig. 5, and the frequencies corresponding to the peaks in the graph are ± 0.1MHz, respectively, and are consistent with the single-tone signal frequencies set in table 1.

2. The signal enters an originating radio frequency model with IQ imbalance parameters, the output spectrum is shown in FIG. 6, the + -0.4 MHz signal in FIG. 6 represents the influence caused by the DC offset of the I path and the Q path, and the + -0.3 MHz and + -0.5 MHz signals represent the signal after the cosine signal is up-converted.

3. The signal after radio frequency output is self-multiplied, and the function is expressed as:

the output spectrum is shown in fig. 7, and it can be seen from fig. 7 that the signal not only includes a zero-frequency signal, but also includes a plus-minus one-frequency-multiplied signal ± 0.1MHz and a plus-minus two-frequency-multiplied signal ± 0.2 MHz.

4. The output enters the receiving end for filtering, the frequency spectrum of the filtered signal is shown in fig. 8, only the signal in the bandwidth of the receiver is reserved in fig. 8, and other periodic signals are filtered.

5. The received signal and the signal of the receiving end with different phases are cross-correlated, and the signal of the receiving end is:

where N characterization divides 2 pi into N, i ═ 0,1,2.. N-1, 2 pi (i-1)/N represents each phase value. Here set to 64 equally divided phases. The correlation curve of the received signal with the cos signal is shown in fig. 9.

From the above, it is found that the maximum value is at the position of 19, and the phase error corresponding to the delay of the filter, etc. is 101.25 °, so the present invention sets the first curve generated by the receiving end as:

6. the originating end generates a signal:

the frequency spectrum is shown in fig. 10, in which the frequencies corresponding to the peaks are ± 0.1MHz, respectively, and are consistent with the single-tone signal frequencies set in table 1.

7. The signal enters an originating radio frequency model with IQ imbalance parameters, the output spectrum is shown in FIG. 11, ± 0.4MHz signal represents the influence caused by DC offset of I path and Q path, and ± 0.3MHz and ± 0.5MHz signals represent the signal after cosine signal up-conversion.

8. The signal after radio frequency output is self-multiplied, and the function is expressed as:

the output spectrum is shown in fig. 12, and it can be seen from fig. 12 that the signal includes not only the zero-frequency signal, but also the plus/minus one-frequency-multiplied signal ± 0.1MHz and the plus/minus two-frequency-multiplied signal ± 0.2 MHz.

9. The output enters the receiving end for filtering, the frequency spectrum of the filtered signal is as shown in fig. 13, only the signal in the bandwidth of the receiver is reserved in fig. 13, and other periodic signals are filtered.

10. The received signal and the signal of the receiving end with different phases are cross-correlated, and the signal of the receiving end is:

where N characterization divides 2 pi into N, i ═ 0,1,2.. N-1, 2 pi (i-1)/N represents each phase value. Here set to 64 equally divided phases. The curve of the received signal after being most correlated with the above signal is shown in fig. 14. The invention finds that the maximum value is at the position of 19, the phase error corresponding to the delay of a filter and the like is 101.25 degrees, therefore, the invention sets the first curve generated by the receiving end as:

11. the originating end generates a signal:

the frequency spectrum is shown in fig. 15, and the frequencies corresponding to the peaks in fig. 15 are 0.1MHz, respectively, and are consistent with the single-tone signal frequencies set in table 1.

12. The signal enters an originating radio frequency model with IQ imbalance parameters, and the output spectrum is as follows: in the figure, the +/-0.4 MHz signal represents the influence caused by the DC offset of the I path and the Q path, and the +/-0.3 MHz signal and the +/-0.5 MHz signal represent the up-converted signal of the sine-cosine signal.

13. The signal after radio frequency output is self-multiplied, and the function is expressed as:

the output spectrum is shown in fig. 17, and it can be seen from fig. 17 that the signal includes not only the zero-frequency signal, but also the plus/minus one-frequency-multiplied signal ± 0.1MHz and the plus/minus two-frequency-multiplied signal ± 0.2 MHz.

14. The output enters the receiving end for filtering, the spectrum of the filtered signal is shown in fig. 18, only the signal in the bandwidth of the receiver is reserved in the graph, and other periodic signals are filtered.

15. The received signal and the signal of the receiving end with different phases are cross-correlated, and the signal of the receiving end is:

where N characterization divides 2 pi into N, i ═ 0,1,2.. N-1, 2 pi (i-1)/N represents each phase value. Here set to 64 equally divided phases. The curves after the received signal is most correlated with the above signal are shown in fig. 19 and 20. The invention finds that the maximum value of the two curves is at the position of 19, and the phase error corresponding to the delay of a filter and the like is 101.25 degrees, so the invention sets the third curve generated by the receiving end as:

16. after finding the accurate phase delay, the transmitting end carries out I-path DC correction to generate a signal:

the frequency spectrum is shown in fig. 21, the frequencies corresponding to the peaks in the graph are ± 0.1MHz, respectively, and are consistent with the single-tone signal frequency set in table 1, and the zero-frequency signal represents the initially transmitted DC correction signal.

17. The signal enters an originating radio frequency model with IQ imbalance parameters, and the output spectrum is as follows:

in the figure, the +/-0.4 MHz signal represents the influence caused by the DC offset of the I path and the Q path, and the +/-0.3 MHz signal and the +/-0.5 MHz signal represent the up-converted signal of the cosine signal.

18. The signals output by the radio frequency are self-multiplied, the output frequency spectrum is shown in fig. 23, and it can be seen from fig. 23 that the signals not only include zero-frequency signals, but also include plus/minus one-frequency-multiplied signals ± 0.1MHz and plus/minus two-frequency-multiplied signals ± 0.2 MHz.

19. The output enters the receiving end for filtering, the frequency spectrum of the filtered signal is as shown in fig. 24, only the signal in the bandwidth of the receiver is reserved in fig. 24, and other periodic signals are filtered.

20. The received signal and the first signal stored in the receiving end are cross-correlated and then data is stored, and the receiving end signal is:

subsequently, 20 different groups of I-path DC test data are sent one by one, and are cross-correlated with equations (4-16), respectively, and the resulting curve is shown in fig. 25. The invention finds that the offset of the I-path DC offset corresponding to the lowest point position is-0.04, and can completely compensate the I-path DC initial error value of 0.04 in the table 1.

21. Then, the transmitting end carries out Q-path DC rectification and generates a signal:

the frequency spectrum is shown in fig. 27, the frequencies corresponding to the peak values in fig. 27 are ± 0.1MHz, respectively, and are consistent with the single-tone signal frequency set in table 1, and the zero-frequency signal represents the initially transmitted I-path and Q-path DC correction signals.

22. The signal enters an originating radio frequency model with IQ imbalance parameters, and the output spectrum is as follows: in the figure, the +/-0.4 MHz signal represents the influence caused by the DC offset of the I path and the Q path, and the +/-0.3 MHz signal and the +/-0.5 MHz signal represent the up-converted signal of the cosine signal.

23. The signals output by the radio frequency are self-multiplied, the output frequency spectrum is shown in fig. 28, and it can be seen from fig. 28 that the signals not only include zero-frequency signals, but also include plus/minus one-frequency-multiplied signals ± 0.1MHz and plus/minus two-frequency-multiplied signals ± 0.2 MHz.

24. The output enters the receiving end for filtering, the frequency spectrum of the filtered signal is as shown in fig. 29, only the signal in the bandwidth of the receiver is reserved in fig. 29, and other periodic signals are filtered.

25. The received signal is cross-correlated with the first signal stored at the receiving end and the data is saved,

the receiving end signals are:

then 20 different groups of Q-path DC test data are sent one by one and are respectively cross-correlated with the equations (4-19), and the obtained curve is shown in figure 30. The invention finds that the deviation of the DC offset of the Q path corresponding to the lowest point position is-0.05, and can completely compensate the initial error value of the DC of the Q path of 0.05 in the table 4-1, so that the compensation method is correct.

26. Subsequently, the transmitting end carries out gain imbalance parameter estimation and generates a signal:

the frequency spectrum is shown in fig. 31, the frequencies corresponding to the peaks in the diagram are ± 0.1MHz, respectively, and are consistent with the single-tone signal frequency set in table 1, and the zero-frequency signal represents the initially transmitted I-path and Q-path DC correction signals. Since the amplitudes of the cos and sin signals are different, the amplitudes of the two signal bins, which are symmetric about the zero frequency, are different.

27. The signal enters an originating radio frequency model with IQ imbalance parameters, and the output spectrum is as follows:

in the figure, the +/-0.4 MHz signal represents the influence caused by the DC offset of the I path and the Q path, and the frequency point has no signal because the existence of a correct estimation value is already counteracted. The + -0.3 MHz and + -0.5 MHz signals represent the up-converted cosine signal.

28. The signal after radio frequency output is self-multiplied, and the function is expressed as:

the output spectrum is shown in fig. 33, which shows that the signal not only includes zero frequency signal, but also includes plus and minus frequency doubling signal + -0.2 MHz, because of I_DCAnd Q_DCAll are zero after correct compensation, so that no signal can be shown at plus and minus one frequency multiplication signal plus or minus 0.1MHz according to the formula and the picture.

29. The output enters the receiving end for filtering, the spectrum of the filtered signal is as shown in fig. 34, only the signal in the bandwidth of the receiver is reserved in fig. 34, and other periodic signals are filtered.

30. And the received signal and a third signal stored by a receiving end are subjected to cross correlation and then data are stored, wherein the receiving end signal is as follows:

the subsequent 20 sets of different gain test data were sent one by one and cross-correlated with equations (4-26), respectively, to obtain the curve shown in fig. 35. The gain imbalance corresponding to the lowest point position is found to be 1.05, and is completely the same as the gain imbalance parameters set in the table 1, so that the estimation algorithm is correct.

31. Then, the transmitting end carries out phase imbalance parameter estimation and generates a signal:

the frequency spectrum is shown in fig. 36, the frequencies corresponding to the peak values in fig. 36 are ± 0.1MHz, respectively, and are consistent with the single-tone signal frequency set in table 1, and the zero-frequency signal represents the initially transmitted I-path and Q-path DC correction signals. Since the amplitudes of the cos and sin signals are different, the amplitudes of the two signal bins, which are symmetric about the zero frequency, are different.

32. The signal enters an originating radio frequency model with IQ imbalance parameters, and the output spectrum is as follows:

33. The signal after radio frequency output is self-multiplied, and the function is expressed as:

the output spectrum is shown in fig. 38, and it can be seen that the signal includes not only the zero-frequency signal but also the plus and minus frequency doubling signal ± 0.2MHz, because of I_DCAnd Q_DCAll are zero after correct compensation, so that no signal can be shown at plus and minus one frequency multiplication signal plus or minus 0.1MHz according to the formula and the picture.

34. The output enters the receiving end for filtering, the frequency spectrum of the filtered signal is as shown in fig. 39, only the signal in the bandwidth of the receiver is reserved in fig. 39, and other periodic signals are filtered.

35. And the received signal and a third signal stored by a receiving end are subjected to cross correlation and then data are stored, wherein the receiving end signal is as follows:

the subsequent 20 sets of different gain test data were sent one by one and cross-correlated with equations (4-27), respectively, to obtain the curve shown in fig. 40. The invention finds that the phase imbalance corresponding to the lowest point position is 5 degrees, which is completely the same as the gain imbalance parameter set in the table 1, so the estimation algorithm is correct.

The invention can be used in any system generating IQ imbalance, and is not limited to a broadband system, and a narrow-band system is still applicable.

Other embodiments than the above examples may be devised by those skilled in the art based on the foregoing disclosure, or by adapting and using knowledge or techniques of the relevant art, and features of various embodiments may be interchanged or substituted and such modifications and variations that may be made by those skilled in the art without departing from the spirit and scope of the present invention are intended to be within the scope of the following claims.

The functionality of the present invention, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium, and all or part of the steps of the method according to the embodiments of the present invention are executed in a computer device (which may be a personal computer, a server, or a network device) and corresponding software. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, or an optical disk, exist in a read-only Memory (RAM), a Random Access Memory (RAM), and the like, for performing a test or actual data in a program implementation.

Claims

1. An outbound IQ correction method, comprising:

2. The IQ correction method according to claim 1, further comprising taking the signal corresponding to the minimum value of the cross-correlation curve to perform I-path and Q-path DC error estimation, gain imbalance parameter estimation and phase imbalance parameter estimation in step S2.

3. The IQ correction method according to any of claims 1 or 2, wherein in step S1, the transmitter transmits three sets of signals TX1, TX2 and TX3, respectively, as:

TX1：

TX2：

TX3：

4. The method of claim 3, wherein in step S2, the sets of sinusoidal signals generated at the receiving end include four sets of sinusoidal signals, denoted as Rx _1(i), Rx _2(i), Rx _3(i), and Rx _4(i), and each set of sinusoidal signals includes N signals with the same frequency and different initial phases, that is:

5. The method for IQ correction according to claim 4, wherein in step S2, three sets of signals TX1, TX2 and TX3 are processed in the receiving channel after self-multiplication to obtain three sets of signals RX1, RX2 and RX3, and then cross-correlated with four sets of sinusoidal signals Rx _1(i), Rx _2(i), Rx _3(i) and Rx _4(i) generated by the receiving end to obtain maximum values, and obtain N1, N2, N3 and N4 respectively:

N1＝max{corr(Rx1,Rx_1(i))|_{i＝0,1,2...N-1}}

N2＝max{corr(Rx2,Rx_2(i))|_{i＝0,1,2...N-1}}

N3＝max{corr(Rx3,Rx_3(i))|_{i＝0,1,2...N-1}}

N4＝max{corr(Rx3,Rx_4(i))|_{i＝0,1,2...N-1}}

the three sets of signals R1, R2, R3 corresponding to the maximum values are:

where corr is the identifier of the cross-correlation.

6. The IQ correction method according to claim 5, wherein in step S2, the range of the I-path DC offset [ -g _ I [ ]_max，+g_I_max]Divide it into N_I+1, the originating transmission signal TX is expressed as:

TX1：

7. The IQ correction method according to claim 5, wherein in step S2, the Q-way DC offset is set to range [ -g _ Q ]_max，+g_Q_max]Divide it into N_Q+1, the originating transmission signal TX is expressed as:

TX2：

wherein i ═ 0,1, … N_Q]Received N_I+1 groups of signals, each correlated with R2 with the smallest corresponding delta_Q＝E_Q(k₁) For the Q-way DC error estimate:

8. The IQ correction method according to claim 5, wherein the gain imbalance parameter is set in the range [ -g ]_max，+g_max]Divide it into N_g+1, the transmission signal TX is expressed as:

TX2：

wherein i ═ 1, … N_g+1]Received N_g+1 sets of signals, which interact with R2 and R3, respectivelyOff, g corresponding to the average of the correlation minima_t＝E_g(k₂) For gain imbalance parameter estimation:

9. The IQ correction method according to claim 5, wherein a parameter range of phase imbalance is defined

Divide it into

And if yes, the sending end sending signal TX is expressed as:

wherein

Received (a)

For phase imbalance parameter estimation:

wherein the content of the first and second substances,

representing the I, Q two-way phase imbalance estimate used for the test,

to obtain the estimated value of the phase imbalance parameter.

10. The IQ correction method according to any of claims 1-9, wherein in step S1, the self-multiplied signals TX are processed in the receiving channel, including filtering and amplification.