CN109474553B - Method and system for estimating signal distortion parameters of terminal transmission path - Google Patents

Method and system for estimating signal distortion parameters of terminal transmission path Download PDF

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CN109474553B
CN109474553B CN201811485498.XA CN201811485498A CN109474553B CN 109474553 B CN109474553 B CN 109474553B CN 201811485498 A CN201811485498 A CN 201811485498A CN 109474553 B CN109474553 B CN 109474553B
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CN109474553A (en
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周亮
贺雷
王帅杰
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Shanghai Mobile Core Communication Technology Co ltd
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Shanghai Eigencomm Communication Technology Co ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/06—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
    • H04L25/061—Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/38—Synchronous or start-stop systems, e.g. for Baudot code
    • H04L25/40—Transmitting circuits; Receiving circuits
    • H04L25/49—Transmitting circuits; Receiving circuits using code conversion at the transmitter; using predistortion; using insertion of idle bits for obtaining a desired frequency spectrum; using three or more amplitude levels ; Baseband coding techniques specific to data transmission systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0018—Arrangements at the transmitter end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0024—Carrier regulation at the receiver end
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/0014—Carrier regulation
    • H04L2027/0024—Carrier regulation at the receiver end
    • H04L2027/0026—Correction of carrier offset

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Abstract

The invention provides a method and a system for estimating signal distortion parameters of a terminal transmitting path, which comprises the following steps: selecting at least three phase deviation values, respectively taking each phase deviation value as a preset IQ mismatch parameter, and carrying out IQ mismatch test to obtain a corresponding first power measurement value; obtaining a phase deviation estimated value and a gain deviation estimated value according to all the phase deviation values and the corresponding first power measured values; the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter; and obtaining a signal distortion parameter according to the IQ mismatch parameter. The invention can reduce the test workload and reduce the estimation time of the signal distortion parameters.

Description

Method and system for estimating signal distortion parameters of terminal transmission path
Technical Field
The present invention relates to the field of mobile communication technologies, and in particular, to a method and a system for estimating signal distortion parameters of a terminal transmit path.
Background
The rf transceiver of the wireless communication system generally has IQ two signals in the transmission path and the reception path: an In-phase signal (I-path) and a Quadrature signal (Q-path). Due to the manufacturing cost, process and power consumption, the local oscillator in the rf transceiver cannot achieve the equal amplitude of the IQ two signals and the precise 90 degree phase difference (i.e. complete orthogonality), so the IQ mismatch occurs in the transmitting channel and the receiving channel.
The method mainly aims at a transmitting end of a terminal, and signal distortions such as direct current offset and the like can be generated in a radio frequency path besides IQ mismatch, wherein the IQ mismatch comprises phase mismatch and amplitude gain mismatch, and the direct current offset comprises I direct current offset and Q direct current offset. Both signal distortions affect the quality of the transmitted signal, so predistortion at baseband is required to remove their effect.
To perform predistortion, specific values of the IQ mismatch parameter and the dc offset parameter need to be estimated first. A commonly used estimation method of IQ mismatch parameters is: when phase mismatch parameters of a transmitter are estimated, amplitude mismatch parameters of the transmitter are fixed, the phase mismatch parameters are scanned successively, a baseband signal is correspondingly generated at a transmitting end in each scanning, and the corresponding phase mismatch parameters when the energy of the baseband signal is minimum in the phase parameter scanning process are found out; and fixing the estimated phase mismatch parameter, scanning the amplitude mismatch parameter one by one, generating a baseband signal at a transmitting end correspondingly in each scanning, and finding out the amplitude mismatch parameter corresponding to the minimum energy of the baseband signal in the amplitude parameter scanning process. The method has the advantages of large testing workload and long time, and if the estimation precision requirement is high, the time is longer.
Disclosure of Invention
The invention aims to provide a method and a system for estimating signal distortion parameters of a terminal transmitting path, which can reduce the test workload and reduce the estimation time of the signal distortion parameters.
The technical scheme provided by the invention is as follows:
a method for estimating signal distortion parameters of a terminal transmission path comprises the following steps: carrying out IQ mismatch parameter estimation on a transmitting channel to obtain IQ mismatch parameters; obtaining a signal distortion parameter according to the IQ mismatch parameter;
wherein the IQ mismatch parameter estimation is:
selecting at least three different phase deviation values, respectively taking each phase deviation value as a preset IQ mismatch parameter, and carrying out IQ mismatch test to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter; obtaining a phase deviation estimated value and a gain deviation estimated value according to all the phase deviation values and the corresponding first power measured values; the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
In the technical scheme, the signal distortion parameters are obtained through least 3 times of measurement, so that the test workload is reduced, and the estimation time of the signal distortion parameters is shortened.
Further preferably, the obtaining of the phase deviation estimated value and the gain deviation estimated value according to all the phase deviation values and the corresponding first power measured values specifically includes: obtaining a phase deviation estimated value and two gain deviation candidate values according to all the phase deviation values and the corresponding first power measured values; combining the phase deviation estimated value and the two gain deviation candidate values respectively, combining each combination into another preset IQ mismatch parameter respectively, and performing IQ mismatch test to obtain a corresponding first power measurement value; and selecting a gain deviation candidate value of the corresponding combination with a small power value from the first power measurement values corresponding to all the combinations as a gain deviation estimated value.
In the technical scheme, the accuracy of the gain deviation estimation value is improved through further 2 times of measurement, so that the estimation accuracy of the signal distortion parameter is improved.
Further preferably, the obtaining a signal distortion parameter according to the IQ mismatch parameter further includes: according to the IQ mismatch parameter, carrying out IQ pre-distortion on the initial baseband signal to obtain an IQ corrected baseband signal; carrying out direct current offset parameter estimation on the transmission channel after IQ correction to obtain a direct current offset parameter; obtaining a signal distortion parameter according to the IQ mismatch parameter and the direct current offset parameter;
wherein the DC offset parameter estimation is as follows:
selecting at least three different I-path direct current offset values, respectively taking each I-path direct current offset value as a preset direct current offset parameter, and performing direct current offset test on the I-path to obtain a second power measurement value corresponding to the I-path direct current offset value; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component; obtaining an I path estimated intermediate value according to all the I path direct current offset values and the corresponding second power measurement values; at least selecting three different Q-path direct current offset values, respectively taking each Q-path direct current offset value as another preset direct current offset parameter, and performing direct current offset test on the Q-path to obtain a second power measurement value corresponding to the Q-path direct current offset value; obtaining a Q-path estimated intermediate value according to the I-path estimated intermediate value, all the Q-path direct current offset values and second power measurement values corresponding to the Q-path direct current offset values; obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; and the I path estimation value and the Q path estimation value form a direct current offset parameter.
In the technical scheme, the method for estimating the IQ mismatch parameter and the direct current offset parameter is provided for the condition that signal distortion has IQ mismatch and direct current offset, and compared with the traditional method, the method reduces the test workload and improves the estimation efficiency.
Further preferably, the obtaining a signal distortion parameter according to the IQ mismatch parameter and the dc offset parameter further includes: the IQ mismatch parameter is used as a first round of IQ mismatch parameter, the direct current offset parameter is used as a first round of direct current offset parameter, and the initial baseband signal is subjected to IQ pre-distortion and direct current pre-offset according to the first round of IQ mismatch parameter and the first round of direct current offset parameter to obtain a first round of corrected baseband signal; taking the baseband signal after the first round of correction as an initial baseband signal, and performing IQ mismatch parameter estimation on the transmission channel after the first round of correction again to obtain IQ mismatch parameters serving as second round of IQ mismatch parameters; and obtaining a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter and the second round IQ mismatch parameter.
Further preferably, the obtaining a signal distortion parameter according to the first round IQ mismatch parameter, the first round dc offset parameter, and the second round IQ mismatch parameter further includes: according to a second round of IQ mismatch parameter, carrying out pre-IQ distortion on the baseband signal after the first round of IQ correction to obtain a second round of IQ corrected baseband signal; taking the baseband signal after the second round of IQ correction as a baseband signal after IQ correction, and performing direct current offset parameter estimation on a transmission channel after the second round of IQ correction to obtain a second round of direct current offset parameter; and obtaining a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter, the second round IQ mismatch parameter and the second round direct current offset parameter.
In the technical scheme, after one round of estimation is performed on IQ mismatch and direct current offset, a second round of estimation is performed on IQ mismatch and direct current offset on the basis of the first round of correction, so that mutual influence of IQ mismatch and direct current offset can be effectively eliminated, and the estimation accuracy of signal distortion parameters is improved.
Further preferably, the pre-IQ distortion of the initial baseband signal according to the pre-IQ mismatch parameter includes: carrying out pre-IQ distortion on an initial baseband signal through the following formula;
I'＝I+Q·tan(θ3)
Figure BDA0001894373410000041
wherein I 'is an in-phase signal of the pre-IQ distorted baseband signal, Q' is a quadrature signal of the pre-IQ distorted baseband signal, I is an in-phase signal of the initial baseband signal, Q is a quadrature signal of the initial baseband signal, ∈3Is a gain deviation estimation value of a preset IQ mismatch parameter, theta3Is the estimated value of the phase deviation of the preset IQ mismatch parameter.
The invention also provides a system for estimating signal distortion parameters of a terminal transmission path, which comprises: an IQ mismatch estimation module for performing IQ mismatch parameter estimation on the transmission path to obtain IQ mismatch parameters; a distortion parameter obtaining module, configured to obtain a signal distortion parameter according to the IQ mismatch parameter;
the IQ mismatch estimation module comprises: a pre-IQ distortion unit for pre-IQ distorting the initial baseband signal; an IQ mismatch test unit, configured to select at least three different phase deviation values, respectively use each phase deviation value as a preset IQ mismatch parameter, and perform IQ mismatch test to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter; an IQ mismatch parameter estimation unit, configured to obtain a phase deviation estimation value and a gain deviation estimation value according to all the phase deviation values and corresponding first power measurement values; and the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
In the technical scheme, the signal distortion parameters are obtained through least 3 times of measurement, so that the test workload is reduced, and the estimation time of the signal distortion parameters is shortened.
Preferably, the IQ pre-distortion unit is further configured to perform IQ pre-distortion on the initial baseband signal according to the IQ mismatch parameter to obtain an IQ-corrected baseband signal; the direct current offset estimation module is used for carrying out direct current offset parameter estimation on the transmission channel after IQ correction to obtain a direct current offset parameter; the distortion parameter obtaining module is further configured to obtain a signal distortion parameter according to the IQ mismatch parameter and the dc offset parameter;
the DC offset estimation module comprises:
a pre-DC offset unit, configured to perform pre-DC offset processing on the baseband signal after IQ correction; the direct current offset testing unit is used for selecting at least three different I-path direct current offset values, taking each I-path direct current offset value as a preset direct current offset parameter, and performing direct current offset testing on the I-path to obtain a second power measurement value corresponding to the I-path direct current offset value; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component; the direct current offset parameter estimation unit is used for obtaining an I-path estimated intermediate value according to all the I-path direct current offset values and the corresponding second power measurement values; the direct current offset testing unit is further used for selecting at least three different Q-path direct current offset values, taking each Q-path direct current offset value as another preset direct current offset parameter, and performing direct current offset testing on the Q-path to obtain a second power measurement value corresponding to the Q-path direct current offset value; the direct current offset parameter estimation unit is further configured to obtain a Q-path estimated intermediate value according to the I-path estimated intermediate value, all the Q-path direct current offset values, and second power measurement values corresponding thereto; obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; and the I path estimation value and the Q path estimation value form a direct current offset parameter.
In the technical scheme, the method for estimating the IQ mismatch parameter and the direct current offset parameter is provided for the condition that signal distortion has IQ mismatch and direct current offset, and compared with the traditional method, the method reduces the test workload and improves the estimation efficiency.
Preferably, the IQ mismatch parameter is used as a first round of IQ mismatch parameter, and the IQ mismatch parameter is used as a second round of IQ mismatch parameter; the pre-dc offset unit is further configured to perform pre-dc offset on the first round of IQ-corrected baseband signals according to the first round of dc offset parameters to obtain first round of corrected baseband signals, where the first round of dc offset parameters are the dc offset parameters; the IQ mismatch estimation module is further configured to use the baseband signal after the first round of correction as an initial baseband signal, perform IQ mismatch parameter estimation on the transmission path after the first round of correction again, and use an obtained IQ mismatch parameter as an IQ mismatch parameter of a second round; the distortion parameter obtaining module is further configured to obtain a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter, and the second round IQ mismatch parameter.
In the technical scheme, after one round of estimation is performed on IQ mismatch and direct current offset, a second round of estimation is performed on IQ mismatch and direct current offset on the basis of the first round of correction, so that mutual influence of IQ mismatch and direct current offset can be effectively eliminated, and the estimation accuracy of signal distortion parameters is improved.
The method and the system for estimating the signal distortion parameters of the terminal transmitting path can bring at least one of the following beneficial effects:
1. the invention can reduce the test workload, reduce the estimation time of the signal distortion parameter and improve the estimation efficiency.
2. The method carries out two rounds of estimation on the IQ mismatch and the direct current offset, and improves the estimation accuracy of IQ mismatch parameters and direct current offset parameters.
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The above features, technical features, advantages and implementations of a method and system for estimating a signal distortion parameter of a transmission path of a terminal will be further described in the following preferred embodiments in a clearly understandable manner with reference to the accompanying drawings.
Fig. 1 is a flowchart of an embodiment of a method for estimating a signal distortion parameter of a transmission path of a terminal according to the present invention;
fig. 2 is a flowchart of another embodiment of a method for estimating signal distortion parameters of a terminal transmission path according to the present invention;
fig. 3 is a flowchart of another embodiment of a method for estimating signal distortion parameters of a terminal transmission path according to the present invention;
FIG. 4 is a schematic diagram illustrating an embodiment of a system for estimating a signal distortion parameter of a transmission path of a terminal according to the present invention;
fig. 5 is a schematic structural diagram of another embodiment of the system for estimating the signal distortion parameter of the terminal transmission path according to the present invention.
The reference numbers illustrate:
110, an IQ mismatch estimation module, 111, a pre-IQ distortion unit, 112, an IQ mismatch test unit, 113, an IQ mismatch parameter estimation unit, 120, a dc offset estimation module, 121, a pre-dc offset unit, 122, a dc offset test unit, 123, a dc offset parameter estimation unit, 130, a distortion parameter acquisition module.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description will be made with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the invention, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.
For the sake of simplicity, the drawings only schematically show the parts relevant to the present invention, and they do not represent the actual structure as a product. In addition, in order to make the drawings concise and understandable, components having the same structure or function in some of the drawings are only schematically illustrated or only labeled. In this document, "one" means not only "only one" but also a case of "more than one".
In one embodiment of the present invention, as shown in fig. 1, a method for estimating a signal distortion parameter of a terminal transmission path includes:
step S100, at least three different phase deviation values are selected, each phase deviation value is respectively used as a preset IQ mismatch parameter, IQ mismatch test is carried out, and a corresponding first power measurement value is obtained; the IQ mismatch test is as follows: at a transmitting end of a terminal, performing pre-IQ distortion on an initial baseband signal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and performing power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter.
Step S200 obtains a phase deviation estimated value and a gain deviation estimated value according to all the phase deviation values and the corresponding first power measurement values.
Specifically, at the terminal transmitting end, a radio frequency signal formed after a baseband signal passes through a transmitting path introduces signal distortion due to the transmitting path. Signal distortion includes IQ mismatch and dc offset.
Assume that the baseband signal is: the I path is a cosine signal, the Q path is a sine signal, IQ mismatch and direct current offset pollution are transmitted through a transmission path, and the data form of the transmitted radio frequency signal is as follows:
y(t)＝[DCI+cos(ωt)]·cos(ωct)-(1+ε)·[DCQ+sin(ωt)]·sin(ωct+θ)
where ε is the IQ mismatch induced gain offset, θ is the IQ mismatch induced phase offset, DCIIs a direct current offset introduced I-way direct current offset, DCQIs Q-path DC offset introduced by DC offset, omega is base band frequency, omegacIs the radio frequency carrier frequency.
If the RF path does not introduce DC offset, or the DC offset has negligible effect, it is equivalent to DC in the above equationI、DCQIs 0.
In order to estimate the influence of ∈, θ, i.e., IQ mismatch, an IQ mismatch test needs to be performed. The IQ mismatch test is: generating a test signal at a baseband of a terminal transmitting end, namely an initial baseband signal (a cosine signal in an I path and a sine signal in a Q path), pre-distorting the initial baseband signal according to a preset IQ mismatch parameter, passing through a transmitting path, passing through a squaring circuit, looping back to a receiving end, and performing Fast Fourier Transform (FFT) on the received baseband signal at the receiving end to obtain power of a double baseband frequency component as a first power measurement value corresponding to the preset IQ mismatch parameter.
The default IQ mismatch parameter generally includes a default phase deviation value and a default gain deviation value, and if only the phase deviation is predistorted, the default gain deviation value is defaulted to 0. The present embodiment is to predistort only the phase deviation. Selecting phase deviation values at will within the estimated phase deviation range, for example, selecting three phase deviation values of-5 °, 0 ° and 5 °, respectively as a preset IQ mismatch parameter (default gain deviation value is 0), and performing IQ mismatch test to obtain three times of P2ω(power of twice frequency component of received sideband signal), i.e.
Figure BDA0001894373410000092
Or selecting three phase deviation values of 0 degrees, 1 degrees and 2 degrees as preset IQ mismatch parameters respectively to perform IQ mismatch test.
Suppose that three phase deviation values of-5 degrees, 0 degrees and 5 degrees are selected to respectively carry out IQ mismatch test to obtain three times of P2ωMeasured value of (i), i.e.
Figure BDA0001894373410000093
According to the three phase deviation values and the corresponding first power measured values, namely-5 degrees, 0 degrees, 5 degrees,
Figure BDA0001894373410000094
Calculating to obtain the estimated value of the phase deviation according to the following formula
Figure BDA0001894373410000091
Figure BDA0001894373410000101
Two gain deviation candidate values epsilon are calculated according to the following formula1、ε2：
Figure BDA0001894373410000102
Figure BDA0001894373410000103
Figure BDA0001894373410000104
Figure BDA0001894373410000105
Figure BDA0001894373410000106
According to epsilon1、ε2Taking the average of the two or taking one of the two or taking the other
Figure BDA0001894373410000107
Figure BDA0001894373410000108
IQ mismatch tests are respectively carried out on the combinations, and the gain deviation candidate value of the corresponding combination with the small first power measurement value is taken as the gain deviation estimation value
Figure BDA0001894373410000109
The selection of at least three different phase deviation values, preferably mutually opposite values, makes the calculation of the phase deviation estimate simpler: suppose that three angles of-x, 0 and x are selected as phase deviation values, IQ mismatch test is respectively carried out to obtain three times of P2ωMeasured value of (i), i.e. P2ω(-x)、P2ω(0)、P2ω(x) The phase deviation estimated value is calculated by the following formula
Figure BDA00018943734100001010
Figure BDA00018943734100001011
In step S500, the phase deviation estimation value and the gain deviation estimation value form an IQ mismatch parameter.
Step S600 obtains signal distortion parameters according to the IQ mismatch parameters.
Specifically, in this embodiment, for the case that the signal distortion has only IQ mismatch or the influence caused by dc offset is negligible, the IQ mismatch parameter is measured at least 3 times to obtain the estimated value of the parameter, thereby greatly saving the estimation time of the signal distortion parameter.
In another embodiment of the present invention, as shown in fig. 2, a method for estimating a signal distortion parameter of a terminal transmission path includes:
step S100, at least three different phase deviation values are selected, each phase deviation value is respectively used as a preset IQ mismatch parameter, IQ mismatch test is carried out, and a corresponding first power measurement value is obtained; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
pre-IQ-distorting the initial baseband signal by:
I'＝I+Q·tan(θ3)
Figure BDA0001894373410000111
wherein I 'is an in-phase signal of the pre-IQ distorted baseband signal, Q' is a quadrature signal of the pre-IQ distorted baseband signal, I is an in-phase signal of the initial baseband signal, Q is a quadrature signal of the initial baseband signal, ∈3Is a gain deviation estimation value of a preset IQ mismatch parameter, theta3Is a phase deviation estimated value of a preset IQ mismatch parameter;
step S210, obtaining a phase deviation estimated value and two gain deviation candidate values according to all the phase deviation values and the corresponding first power measurement values;
step S220, combining the phase deviation estimated value and the two gain deviation candidate values respectively, combining each combination into another preset IQ mismatch parameter respectively, and carrying out IQ mismatch test to obtain a corresponding first power measurement value;
step S230 selects a gain deviation candidate value of the corresponding combination with a smaller power value from the first power measurement values corresponding to all the combinations as a gain deviation estimation value;
specifically, the estimated phase deviation value and the two gain deviation candidate values are combined respectively to obtain two combinations, each combination is combined as another preset IQ mismatch parameter, and IQ mismatch is performedTest to obtain two times of P2ωAnd (6) measuring the values. For two times P2ωThe measured values are compared, and the gain deviation candidate value in the corresponding combination which is smaller is used as the gain deviation estimated value.
Step S500, the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter;
step S610 is to carry out pre-IQ distortion on the initial baseband signal according to the IQ mismatch parameter to obtain the baseband signal after IQ correction;
step S620, at least three different I-path direct current offset values are selected, each I-path direct current offset value is respectively used as a preset direct current offset parameter, and direct current offset test is carried out on an I-path to obtain a second power measurement value corresponding to the I-path direct current offset value; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component;
step S630, obtaining an I-path estimated intermediate value according to all the I-path direct current offset values and the corresponding second power measurement values;
step S640 at least selects three different Q-path direct current offset values, each Q-path direct current offset value is respectively used as another preset direct current offset parameter, and direct current offset test is carried out on the Q-path to obtain a second power measurement value corresponding to the Q-path direct current offset value;
step S650, obtaining a Q-path estimated intermediate value according to the I-path estimated intermediate value, all the Q-path direct current offset values and the corresponding second power measurement values;
step S660, obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; the I path estimation value and the Q path estimation value form a direct current offset parameter;
step S670 obtains a signal distortion parameter according to the IQ mismatch parameter and the dc offset parameter.
Specifically, for a radio frequency path with both IQ mismatch and DC offset, in addition to IQ correction, DC offset correction (DC correction for short) is required, so after estimating IQ mismatch parameters, DC offset parameters are required to be estimated again.
And performing IQ pre-distortion on the initial baseband signal according to the IQ mismatch parameter to eliminate the influence of IQ mismatch introduced by a transmission channel, namely performing IQ correction to obtain an IQ corrected baseband signal. Then, estimation of the dc offset parameter is performed, for example:
performing direct current offset x on an I shunt signal of the IQ corrected baseband signal, looping back to a receiving end of a terminal after passing through a transmitting channel and a squaring circuit, performing FFT on the baseband signal at the receiving end to obtain a power value on a frequency component multiplied by one, and recording the power value as a second power measurement value Pω(+ x), calculating a direct current offset test in the process; repeating the DC offset test twice to obtain a second power measurement value P corresponding to the DC offset 0ω(0) And a second power measurement P corresponding to the DC offset-xω(-x)。
Direct current offset values x, 0, -x according to I branch and corresponding power value Pω(+x)、Pω(0)、Pω(-x) calculating the way I estimated mean DC according to the following formulaI'：
Figure BDA0001894373410000131
Performing DC offset test on the Q branch by using a similar method according to DC offset values x-x of the Q branch and corresponding second power measurement value
Figure BDA0001894373410000138
Calculating the Q-path estimated intermediate value DC according to the following formulaQ'：
Figure BDA0001894373410000132
Wherein
Figure BDA0001894373410000133
Is the phase deviation estimate of the IQ mismatch parameters.
According to DCI'、DCQ' obtaining the estimated I-path value DC according to the following formulaIQ-path estimated value DCQ；
Figure BDA0001894373410000134
Figure BDA0001894373410000135
Wherein
Figure BDA0001894373410000136
Is a gain deviation estimate of the IQ mismatch parameters,
Figure BDA0001894373410000137
is the phase deviation estimate of the IQ mismatch parameters. DC (direct current)I、DCQConstituting a dc offset parameter.
In another embodiment of the present invention, as shown in fig. 3, a method for estimating a signal distortion parameter of a terminal transmission path includes:
step S100, at least three different phase deviation values are selected, each phase deviation value is respectively used as a preset IQ mismatch parameter, IQ mismatch test is carried out, and a corresponding first power measurement value is obtained; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
pre-IQ-distorting the initial baseband signal by:
I'＝I+Q·tan(θ3)
Figure BDA0001894373410000141
wherein I 'is an in-phase signal of the pre-IQ distorted baseband signal, Q' is a quadrature signal of the pre-IQ distorted baseband signal, I is an in-phase signal of the initial baseband signal, Q is a quadrature signal of the initial baseband signal, ∈3Is a gain deviation estimation value of a preset IQ mismatch parameter, theta3Is a phase deviation estimated value of a preset IQ mismatch parameter;
step S210, obtaining a phase deviation estimated value and two gain deviation candidate values according to all the phase deviation values and the corresponding first power measurement values;
step S220, combining the phase deviation estimated value and the two gain deviation candidate values respectively, combining each combination into another preset IQ mismatch parameter respectively, and carrying out IQ mismatch test to obtain a corresponding first power measurement value;
step S230 selects a gain deviation candidate value of the corresponding combination with a smaller power value from the first power measurement values corresponding to all the combinations as a gain deviation estimation value;
step S500, the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter;
step S610 is to carry out pre-IQ distortion on the initial baseband signal according to the IQ mismatch parameter to obtain the baseband signal after IQ correction;
step S620, at least three different I-path direct current offset values are selected, each I-path direct current offset value is respectively used as a preset direct current offset parameter, and direct current offset test is carried out on an I-path to obtain a second power measurement value corresponding to the I-path direct current offset value; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component;
step S630, obtaining an I-path estimated intermediate value according to all the I-path direct current offset values and the corresponding second power measurement values;
step S640 at least selects three different Q-path direct current offset values, each Q-path direct current offset value is respectively used as another preset direct current offset parameter, and direct current offset test is carried out on the Q-path to obtain a second power measurement value corresponding to the Q-path direct current offset value;
step S650, obtaining a Q-path estimated intermediate value according to the I-path estimated intermediate value, all the Q-path direct current offset values and the corresponding second power measurement values;
step S660, obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; the I path estimation value and the Q path estimation value form a direct current offset parameter;
step S671, the IQ mismatch parameter is used as a first round of IQ mismatch parameter, the direct current offset parameter is used as a first round of direct current offset parameter, and pre-IQ distortion and pre-direct current offset are carried out on an initial baseband signal according to the first round of IQ mismatch parameter and the first round of direct current offset parameter to obtain a first round of corrected baseband signal;
step S672 takes the baseband signal after the first round of correction as an initial baseband signal, carries out IQ mismatch parameter estimation on the transmission channel after the first round of correction again, repeats the steps S100-S500, and takes the obtained IQ mismatch parameter as a second round of IQ mismatch parameter;
step S673, according to the second round IQ mismatch parameter, carrying out pre-IQ distortion on the baseband signal after the first round of correction to obtain a second round IQ corrected baseband signal;
step S674, the baseband signal after the second round of IQ correction is used as the baseband signal after IQ correction, the direct current offset parameter estimation is carried out on the transmitting path after the second round of IQ correction, and the steps S620 to S660 are repeated to obtain a second round of direct current offset parameter;
step S675 obtains a signal distortion parameter according to the first round IQ mismatch parameter, the first round dc offset parameter, the second round IQ mismatch parameter, and the second round dc offset parameter. Specifically, in order to eliminate the mutual influence between the IQ mismatch and the dc offset and improve the estimation accuracy of the signal distortion parameter, after one round of estimation is performed on the IQ mismatch and the dc offset, a first round of correction is performed on the transmission path according to a first round of IQ mismatch parameter and a first round of dc offset parameter, and then a second round of estimation is performed on the IQ mismatch and the dc offset on the basis:
according to the first round of IQ mismatch parameters, carrying out pre-IQ distortion on the initial baseband signals, then according to the first round of direct current offset parameters, carrying out pre-direct current offset, namely subtracting the first round of direct current offset parameters from the path I and the path Q respectively to obtain first round corrected baseband signals, and simultaneously carrying out first round correction on the transmitting path.
And taking the baseband signal after the first round of correction as an initial baseband signal, performing IQ mismatch parameter estimation and direct current offset parameter estimation on the transmission channel after the first round of correction again, repeating the IQ mismatch parameter estimation method and the direct current offset parameter estimation method for the first round, taking the IQ mismatch parameter estimation value obtained again as an IQ mismatch parameter for the second round, and taking the direct current offset parameter estimation value obtained again as a direct current offset parameter for the second round.
Adding the phase deviation estimated value of the first round of IQ mismatch parameters and the phase deviation estimated value of the second round of IQ mismatch parameters to obtain a target phase deviation estimated value; gain deviation estimated value epsilon according to first round IQ mismatch parameterround1An estimate of gain deviation epsilon from the second round IQ mismatch parameterround2By ε ═ 1+ εround1)×(1+εround2) -1 obtaining a target gain deviation estimate; the target phase deviation estimated value and the target gain deviation estimated value form an IQ mismatch parameter;
adding the first round of direct current offset parameters and the second round of direct current offset parameters correspondingly and respectively to obtain an I-path target estimation value and a Q-path target estimation value; the I path target estimation value and the Q path target estimation value form a direct current offset parameter. The IQ mismatch parameter and the dc offset parameter constitute a signal distortion parameter. In one embodiment of the present invention, as shown in fig. 4, a system for estimating signal distortion parameters of a terminal transmission path includes:
an IQ mismatch estimation module 110, configured to perform IQ mismatch parameter estimation on a transmission path to obtain an IQ mismatch parameter;
a distortion parameter obtaining module 130, configured to obtain a signal distortion parameter according to the IQ mismatch parameter;
the IQ mismatch estimation module comprises:
a pre-IQ distortion unit 111, configured to perform pre-IQ distortion on the initial baseband signal according to a preset IQ mismatch parameter;
an IQ mismatch test unit 112, configured to select at least three different phase deviation values, and perform an IQ mismatch test using each phase deviation value as a preset IQ mismatch parameter to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
an IQ mismatch parameter estimation unit 113, configured to obtain a phase deviation estimation value and a gain deviation estimation value according to all the phase deviation values and corresponding first power measurement values; the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
Specifically, at the terminal transmitting end, a radio frequency signal formed after a baseband signal passes through a transmitting path introduces signal distortion due to the transmitting path. Signal distortion includes IQ mismatch and dc offset.
Assume that the baseband signal is: the I path is a cosine signal, the Q path is a sine signal, IQ mismatch and direct current offset pollution are transmitted through a transmission path, and the data form of the transmitted radio frequency signal is as follows:
y(t)＝[DCI+cos(ωt)]·cos(ωct)-(1+ε)·[DCQ+sin(ωt)]·sin(ωct+θ)
where ε is the IQ mismatch induced gain offset, θ is the IQ mismatch induced phase offset, DCIIs a direct current offset induced direct current offset of path I, DCQIs Q-path DC offset introduced by DC offset, omega is base band frequency, omegacIs the radio frequency carrier frequency.
If the RF path does not introduce DC offset, or the DC offset has negligible effect, it is equivalent to DC in the above equationI、DCQIs 0.
In order to estimate the influence of ∈, θ, i.e., IQ mismatch, an IQ mismatch test needs to be performed. The IQ mismatch test is: generating a test signal at a baseband of a terminal transmitting end, namely an initial baseband signal (a cosine signal in an I path and a sine signal in a Q path), pre-distorting the initial baseband signal according to a preset IQ mismatch parameter, passing through a transmitting path, passing through a squaring circuit, looping back to a receiving end, and performing Fast Fourier Transform (FFT) on the received baseband signal at the receiving end to obtain power of a double baseband frequency component as a first power measurement value corresponding to the preset IQ mismatch parameter.
The default IQ mismatch parameter generally includes a default phase deviation value and a default gain deviation value, and if only the phase deviation is predistorted, the default gain deviation value is defaulted to 0. The present embodiment is to predistort only the phase deviation. Selecting a phase deviation value at will within the estimated phase deviation range, for example, selecting three phase deviation values of-5 o, 0o and 5 degrees as a preset IQ mismatch parameter (default gain deviation value is 0), and performing IQ mismatch test to obtain three times of P2ω(power of twice frequency component of received sideband signal), i.e.
Figure BDA0001894373410000184
Or selecting three phase deviation values of 0 degrees, 1 degrees and 2 degrees as preset IQ mismatch parameters respectively to perform IQ mismatch test.
Suppose that three phase deviation values of-5 degrees, 0 degrees and 5 degrees are selected to respectively carry out IQ mismatch test to obtain three times of P2ωMeasured value of (i), i.e.
Figure BDA0001894373410000185
According to the three phase deviation values and the corresponding first power measured values, namely-5 degrees, 0 degrees, 5 degrees,
Figure BDA0001894373410000183
Calculating to obtain the estimated value of the phase deviation according to the following formula
Figure BDA0001894373410000181
Figure BDA0001894373410000182
Two gain deviation candidate values epsilon are calculated according to the following formula1、ε2：
Figure BDA0001894373410000191
Figure BDA0001894373410000192
Figure BDA0001894373410000193
Figure BDA0001894373410000194
Figure BDA0001894373410000195
According to epsilon1、ε2Taking the average of the two or taking one of the two or taking the other
Figure BDA0001894373410000196
Figure BDA0001894373410000197
IQ mismatch tests are respectively carried out on the combinations, and the gain deviation candidate value of the corresponding combination with the small first power measurement value is taken as the gain deviation estimation value
Figure BDA00018943734100001910
The selection of at least three different phase deviation values, preferably mutually opposite values, makes the calculation of the phase deviation estimate simpler: suppose that three angles of-x, 0 and x are selected as phase deviation values, IQ mismatch test is respectively carried out to obtain three times of P2ωMeasured value of (i), i.e. P2ω(-x)、P2ω(0)、P2ω(x) The phase deviation estimated value is calculated by the following formula
Figure BDA0001894373410000198
Figure BDA0001894373410000199
In the embodiment, for the case that the signal distortion only has IQ mismatch or the influence caused by the dc offset is negligible, the estimation value of the IQ mismatch parameter can be obtained by measuring the parameter for at least 3 times, thereby greatly saving the estimation time of the signal distortion parameter.
In another embodiment of the present invention, as shown in fig. 4, a system for estimating a signal distortion parameter of a transmission path of a terminal includes:
an IQ mismatch estimation module 110, configured to perform IQ mismatch parameter estimation on a transmission path to obtain an IQ mismatch parameter;
the IQ mismatch estimation module 110 comprises:
a pre-IQ distortion unit 111, configured to perform pre-IQ distortion on the initial baseband signal according to a preset IQ mismatch parameter;
an IQ mismatch test unit 112, configured to select at least three different phase deviation values, and perform an IQ mismatch test using each phase deviation value as a preset IQ mismatch parameter to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
the pre-IQ distortion unit 111 performs pre-IQ distortion on the initial baseband signal by the following formula;
I'＝I+Q·tan(θ3)
Figure BDA0001894373410000201
wherein I 'is an in-phase signal of the pre-IQ distorted baseband signal, Q' is a quadrature signal of the pre-IQ distorted baseband signal, I is an in-phase signal of the initial baseband signal, Q is a quadrature signal of the initial baseband signal, ∈3Is a gain deviation estimation value of a preset IQ mismatch parameter, theta3Is the estimated value of the phase deviation of the preset IQ mismatch parameter.
An IQ mismatch parameter estimation unit 113, configured to obtain a phase deviation estimation value and two gain deviation candidate values according to all the phase deviation values and corresponding first power measurement values;
the IQ mismatch testing unit 112 is further configured to combine the phase deviation estimated value and the two gain deviation candidate values, combine each combination as another preset IQ mismatch parameter, and perform an IQ mismatch test to obtain a corresponding first power measurement value;
the IQ mismatch parameter estimation unit 113 is further configured to select a gain offset candidate value of the corresponding combination with a smaller power value from the first power measurement values corresponding to all the combinations as a gain offset estimation value; and the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
Specifically, the estimated phase deviation value and the two gain deviation candidate values are combined respectively to obtain two combinations, each combination is combined into another preset IQ mismatch parameter respectively, IQ mismatch test is carried out, and two times of P mismatch are obtained2ωAnd (6) measuring the values. For two times P2ωThe measured values are compared, and the gain deviation candidate value in the corresponding combination which is smaller is used as the gain deviation estimated value.
The pre-IQ distortion unit 111 is further configured to perform pre-IQ distortion on the initial baseband signal according to the IQ mismatch parameter, so as to obtain an IQ-corrected baseband signal;
a dc offset estimation module 120, configured to perform dc offset parameter estimation on the transmission path after IQ correction to obtain a dc offset parameter;
a distortion parameter obtaining module 130, configured to obtain a signal distortion parameter according to the IQ mismatch parameter and the dc offset parameter;
the DC offset estimation module comprises:
a pre-dc offset unit 121, configured to perform pre-dc offset processing on the baseband signal after IQ correction;
the dc offset test unit 122 is configured to select at least three different I-path dc offset values, respectively use each I-path dc offset value as a preset dc offset parameter, and perform a dc offset test on the I-branch path to obtain a second power measurement value corresponding to the I-branch path; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component;
a dc offset parameter estimation unit 123, configured to obtain an I-path estimated intermediate value according to all I-path dc offset values and second power measurement values corresponding to the I-path dc offset values;
the dc offset test unit 122 is further configured to select at least three different Q-path dc offset values, respectively use each Q-path dc offset value as another preset dc offset parameter, and perform a dc offset test on the Q-path to obtain a second power measurement value corresponding to the Q-path dc offset value;
the dc offset parameter estimation unit 123 is further configured to obtain a Q-path estimated intermediate value according to the I-path estimated intermediate value, all Q-path dc offset values, and second power measurement values corresponding thereto; obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; and the I path estimation value and the Q path estimation value form a direct current offset parameter.
Specifically, for a radio frequency path with both IQ mismatch and DC offset, in addition to IQ correction, DC offset correction (DC correction for short) is required, so after estimating IQ mismatch parameters, DC offset parameters are required to be estimated again.
And performing IQ pre-distortion on the initial baseband signal according to the IQ mismatch parameter to eliminate the influence of IQ mismatch introduced by a transmission channel, namely performing IQ correction to obtain an IQ corrected baseband signal. Then, estimation of the dc offset parameter is performed, for example:
performing direct current offset x on an I shunt signal of the IQ corrected baseband signal, looping back to a receiving end of a terminal after passing through a transmitting channel and a squaring circuit, performing FFT on the baseband signal at the receiving end to obtain a power value on a frequency component multiplied by one, and recording the power value as a second power measurement value Pω(+ x), calculating a direct current offset test in the process; repeating the DC offset test twice to obtain a second power measurement value P corresponding to the DC offset 0ω(0) And a second power measurement P corresponding to the DC offset-xω(-x)。
Direct current offset values x, 0, -x according to I branch and corresponding power value Pω(+x)、Pω(0)、Pω(-x) calculating the way I estimated mean DC according to the following formulaI'：
Figure BDA0001894373410000221
Performing DC offset test on the Q branch by using a similar method according to DC offset values x-x of the Q branch and corresponding second power measurement value
Figure BDA0001894373410000224
Calculating the Q-path estimated intermediate value DC according to the following formulaQ'：
Figure BDA0001894373410000222
Wherein
Figure BDA0001894373410000223
Is the phase deviation estimate of the IQ mismatch parameters.
According to DCI'、DCQ' obtaining the estimated I-path value DC according to the following formulaIQ-path estimated value DCQ；
Figure BDA0001894373410000231
Figure BDA0001894373410000232
Wherein
Figure BDA0001894373410000233
Is a gain deviation estimate of the IQ mismatch parameters,
Figure BDA0001894373410000234
is the phase deviation estimate of the IQ mismatch parameters. DC (direct current)I、DCQConstituting a dc offset parameter.
In another embodiment of the present invention, as shown in fig. 5, a system for estimating a signal distortion parameter of a transmission path of a terminal includes:
an IQ mismatch estimation module 110, configured to perform IQ mismatch parameter estimation on a transmission path to obtain an IQ mismatch parameter;
the IQ mismatch estimation module 110 comprises:
a pre-IQ distortion unit 111, configured to perform pre-IQ distortion on the initial baseband signal according to a preset IQ mismatch parameter;
an IQ mismatch test unit 112, configured to select at least three different phase deviation values, and perform an IQ mismatch test using each phase deviation value as a preset IQ mismatch parameter to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
the pre-IQ distortion unit 111 performs pre-IQ distortion on the initial baseband signal by the following formula;
I'＝I+Q·tan(θ3)
Figure BDA0001894373410000235
wherein I 'is an in-phase signal of the pre-IQ distorted baseband signal, Q' is a quadrature signal of the pre-IQ distorted baseband signal, I is an in-phase signal of the initial baseband signal, Q is a quadrature signal of the initial baseband signal, ∈3Is a gain deviation estimation value of a preset IQ mismatch parameter, theta3Is the estimated value of the phase deviation of the preset IQ mismatch parameter.
An IQ mismatch parameter estimation unit 113, configured to obtain a phase deviation estimation value and two gain deviation candidate values according to all the phase deviation values and corresponding first power measurement values;
the IQ mismatch testing unit 112 is further configured to combine the phase deviation estimated value and the two gain deviation candidate values, combine each combination as another preset IQ mismatch parameter, and perform an IQ mismatch test to obtain a corresponding first power measurement value;
the IQ mismatch parameter estimation unit 113 is further configured to select a gain offset candidate value of the corresponding combination with a smaller power value from the first power measurement values corresponding to all the combinations as a gain offset estimation value; and the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
The pre-IQ distortion unit 111 is further configured to perform pre-IQ distortion on the initial baseband signal according to the IQ mismatch parameter, so as to obtain an IQ-corrected baseband signal;
a dc offset estimation module 120, configured to perform dc offset parameter estimation on the transmission path after IQ correction to obtain a dc offset parameter;
the dc offset estimation module 120 includes:
a pre-dc offset unit 121, configured to perform pre-dc offset processing on the baseband signal after IQ correction;
the dc offset test unit 122 is configured to select at least three different I-path dc offset values, respectively use each I-path dc offset value as a preset dc offset parameter, and perform a dc offset test on the I-branch path to obtain a second power measurement value corresponding to the I-branch path; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component;
a dc offset parameter estimation unit 123, configured to obtain an I-path estimated intermediate value according to all I-path dc offset values and second power measurement values corresponding to the I-path dc offset values;
the dc offset test unit 122 is further configured to select at least three different Q-path dc offset values, respectively use each Q-path dc offset value as another preset dc offset parameter, and perform a dc offset test on the Q-path to obtain a second power measurement value corresponding to the Q-path dc offset value;
the dc offset parameter estimation unit 123 is further configured to obtain a Q-path estimated intermediate value according to the I-path estimated intermediate value, all Q-path dc offset values, and second power measurement values corresponding thereto; obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; and the I path estimation value and the Q path estimation value form a direct current offset parameter.
The pre-IQ distortion unit 111 is further configured to use the IQ mismatch parameter as a first round of IQ mismatch parameter, and perform pre-IQ distortion on an initial baseband signal according to the first round of IQ mismatch parameter to obtain a first round of IQ-corrected baseband signal;
the pre-dc offset unit 121 is further configured to perform pre-dc offset on the first round of IQ-corrected baseband signals according to the first round of dc offset parameters to obtain first round of corrected baseband signals, where the first round of dc offset parameters are the dc offset parameters;
the IQ mismatch estimation module 110 is further configured to use the baseband signal after the first round of correction as an initial baseband signal, perform IQ mismatch parameter estimation on the transmission path after the first round of correction again, and use an obtained IQ mismatch parameter as an IQ mismatch parameter of a second round;
the pre-IQ distortion unit 111 is further configured to perform pre-IQ distortion on the baseband signal after the first round of IQ mismatch according to a second round of IQ mismatch parameters, so as to obtain a second round of IQ-corrected baseband signal;
the dc offset estimation module 120 is further configured to use the baseband signal after the second round of IQ correction as a baseband signal after IQ correction, and perform dc offset parameter estimation on the transmission path after the second round of IQ correction to obtain a second round of dc offset parameters;
a distortion parameter obtaining module 130, configured to obtain a signal distortion parameter according to the first round IQ mismatch parameter, the first round dc offset parameter, the second round IQ mismatch parameter, and the second round dc offset parameter.
Specifically, in order to eliminate the mutual influence between the IQ mismatch and the dc offset and improve the estimation accuracy of the signal distortion parameter, after one round of estimation is performed on the IQ mismatch and the dc offset, a first round of correction is performed on the transmission path according to a first round of IQ mismatch parameter and a first round of dc offset parameter, and then a second round of estimation is performed on the IQ mismatch and the dc offset on the basis:
according to the first round of IQ mismatch parameters, carrying out pre-IQ distortion on the initial baseband signals, then according to the first round of direct current offset parameters, carrying out pre-direct current offset, namely subtracting the first round of direct current offset parameters from the path I and the path Q respectively to obtain first round corrected baseband signals, and simultaneously carrying out first round correction on the transmitting path.
And taking the baseband signal after the first round of correction as an initial baseband signal, performing IQ mismatch parameter estimation and direct current offset parameter estimation on the transmission channel after the first round of correction again, repeating the IQ mismatch parameter estimation method and the direct current offset parameter estimation method for the first round, taking the IQ mismatch parameter estimation value obtained again as an IQ mismatch parameter for the second round, and taking the direct current offset parameter estimation value obtained again as a direct current offset parameter for the second round.
Adding the phase deviation estimated value of the first round of IQ mismatch parameters and the phase deviation estimated value of the second round of IQ mismatch parameters to obtain a target phase deviation estimated value; gain deviation estimated value epsilon according to first round IQ mismatch parameterround1An estimate of gain deviation epsilon from the second round IQ mismatch parameterround2By ε ═ 1+ εround1)×(1+εround2) -1 obtaining a target gain deviation estimate; the target phase deviation estimated value and the target gain deviation estimated value form an IQ mismatch parameter;
adding the first round of direct current offset parameters and the second round of direct current offset parameters correspondingly and respectively to obtain an I-path target estimation value and a Q-path target estimation value; the I path target estimation value and the Q path target estimation value form a direct current offset parameter. The IQ mismatch parameter and the dc offset parameter constitute a signal distortion parameter.
It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (9)

1. A method for estimating signal distortion parameters for a transmission path of a terminal, comprising:
carrying out IQ mismatch parameter estimation on a transmitting channel to obtain IQ mismatch parameters; the IQ mismatch parameters comprise phase deviation and gain deviation of I, Q two-path signals caused by IQ mismatch of the transmission path;
obtaining a signal distortion parameter according to the IQ mismatch parameter;
wherein the IQ mismatch parameter estimation is:
selecting at least three different phase deviation values, respectively taking each phase deviation value as a preset IQ mismatch parameter, and carrying out IQ mismatch test to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
obtaining a phase deviation estimated value and two gain deviation candidate values according to all the phase deviation values and the corresponding first power measured values;
combining the phase deviation estimated value and the two gain deviation candidate values respectively, combining each combination into another preset IQ mismatch parameter respectively, and performing IQ mismatch test to obtain a corresponding first power measurement value;
selecting a gain deviation candidate value of the corresponding combination with a small power value from first power measurement values corresponding to all the combinations as a gain deviation estimated value;
the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
2. The method according to claim 1, wherein the obtaining of the signal distortion parameter according to the IQ mismatch parameter further comprises:
according to the IQ mismatch parameter, carrying out IQ pre-distortion on the initial baseband signal to obtain an IQ corrected baseband signal;
carrying out direct current offset parameter estimation on the transmission channel after IQ correction to obtain a direct current offset parameter;
obtaining a signal distortion parameter according to the IQ mismatch parameter and the direct current offset parameter;
wherein the DC offset parameter estimation is as follows:
selecting at least three different I-path direct current offset values, respectively taking each I-path direct current offset value as a preset direct current offset parameter, and performing direct current offset test on the I-path to obtain a second power measurement value corresponding to the I-path direct current offset value; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component;
obtaining an I path estimated intermediate value according to all the I path direct current offset values and the corresponding second power measurement values;
at least selecting three different Q-path direct current offset values, respectively taking each Q-path direct current offset value as another preset direct current offset parameter, and performing direct current offset test on the Q-path to obtain a second power measurement value corresponding to the Q-path direct current offset value;
obtaining a Q-path estimated intermediate value according to the I-path estimated intermediate value, all the Q-path direct current offset values and second power measurement values corresponding to the Q-path direct current offset values;
obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; and the I path estimation value and the Q path estimation value form a direct current offset parameter.
3. The method according to claim 2, wherein the method for estimating the signal distortion parameter of the terminal transmission path obtains the signal distortion parameter according to the IQ mismatch parameter and the dc offset parameter, and further comprises:
the IQ mismatch parameter is used as a first round of IQ mismatch parameter, the direct current offset parameter is used as a first round of direct current offset parameter, and the initial baseband signal is subjected to IQ pre-distortion and direct current pre-offset according to the first round of IQ mismatch parameter and the first round of direct current offset parameter to obtain a first round of corrected baseband signal;
taking the baseband signal after the first round of correction as an initial baseband signal, and performing IQ mismatch parameter estimation on the transmission channel after the first round of correction again to obtain IQ mismatch parameters serving as second round of IQ mismatch parameters;
and obtaining a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter and the second round IQ mismatch parameter.
4. The method according to claim 3, wherein the obtaining of the signal distortion parameter according to the first round of IQ mismatch parameters, the first round of dc offset parameters, and the second round of IQ mismatch parameters further comprises:
according to a second round of IQ mismatch parameter, carrying out pre-IQ distortion on the baseband signal after the first round of IQ correction to obtain a second round of IQ corrected baseband signal;
taking the baseband signal after the second round of IQ correction as a baseband signal after IQ correction, and performing direct current offset parameter estimation on a transmission channel after the second round of IQ correction to obtain a second round of direct current offset parameter;
and obtaining a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter, the second round IQ mismatch parameter and the second round direct current offset parameter.
5. The method according to claim 1, wherein the pre-IQ distorting the initial baseband signal according to the pre-set IQ mismatch parameter comprises:
carrying out pre-IQ distortion on an initial baseband signal through the following formula;
I'＝I+Q·tan(θ3)
Figure FDA0002399947550000031
wherein I' is the pre-IQ distortionThe in-phase signal of the post baseband signal, Q' is the quadrature signal of the pre-IQ distorted baseband signal, I is the in-phase signal of the initial baseband signal, Q is the quadrature signal of the initial baseband signal, ∈3Is a gain deviation estimation value of a preset IQ mismatch parameter, theta3Is the estimated value of the phase deviation of the preset IQ mismatch parameter.
6. A system for estimating signal distortion parameters for a transmit path of a terminal, comprising:
an IQ mismatch estimation module for performing IQ mismatch parameter estimation on the transmission path to obtain IQ mismatch parameters; the IQ mismatch parameters comprise phase deviation and gain deviation of I, Q two-path signals caused by IQ mismatch of the transmission path;
a distortion parameter obtaining module, configured to obtain a signal distortion parameter according to the IQ mismatch parameter;
the IQ mismatch estimation module comprises:
a pre-IQ distortion unit for pre-IQ distorting the initial baseband signal;
an IQ mismatch test unit, configured to select at least three different phase deviation values, respectively use each phase deviation value as a preset IQ mismatch parameter, and perform IQ mismatch test to obtain a corresponding first power measurement value; the IQ mismatch test is as follows: carrying out pre-IQ distortion on an initial baseband signal at a transmitting end of a terminal according to a preset IQ mismatch parameter, looping back to a receiving end of the terminal after passing through a transmitting channel and a squaring circuit, and carrying out power test on a frequency component twice of the baseband signal at the receiving end to obtain a first power measurement value corresponding to the preset IQ mismatch parameter;
an IQ mismatch parameter estimation unit, configured to obtain a phase deviation estimation value and two gain deviation candidate values according to all the phase deviation values and corresponding first power measurement values; combining the phase deviation estimated value and the two gain deviation candidate values respectively, combining each combination into another preset IQ mismatch parameter respectively, and performing IQ mismatch test to obtain a corresponding first power measurement value; selecting a gain deviation candidate value of the corresponding combination with a small power value from first power measurement values corresponding to all the combinations as a gain deviation estimated value; and the phase deviation estimated value and the gain deviation estimated value form an IQ mismatch parameter.
7. The system according to claim 6, wherein said system comprises:
the pre-IQ distortion unit is further configured to perform pre-IQ distortion on the initial baseband signal according to the IQ mismatch parameter to obtain an IQ-corrected baseband signal;
the direct current offset estimation module is used for carrying out direct current offset parameter estimation on the transmission channel after IQ correction to obtain a direct current offset parameter;
the distortion parameter obtaining module is further configured to obtain a signal distortion parameter according to the IQ mismatch parameter and the dc offset parameter;
the DC offset estimation module comprises:
a pre-DC offset unit, configured to perform pre-DC offset processing on the baseband signal after IQ correction;
the direct current offset testing unit is used for selecting at least three different I-path direct current offset values, taking each I-path direct current offset value as a preset direct current offset parameter, and performing direct current offset testing on the I-path to obtain a second power measurement value corresponding to the I-path direct current offset value; the DC offset test is as follows: at a transmitting end of the terminal, pre-DC offset processing is carried out on the baseband signal after IQ correction according to a preset DC offset parameter at an I shunt or a Q shunt, the baseband signal passes through a transmitting channel and a squaring circuit and then returns to a receiving end of the terminal, and power testing is carried out on the frequency component of the baseband signal at the receiving end to obtain a second power measurement value corresponding to the frequency component;
the direct current offset parameter estimation unit is used for obtaining an I-path estimated intermediate value according to all the I-path direct current offset values and the corresponding second power measurement values;
the direct current offset testing unit is further used for selecting at least three different Q-path direct current offset values, taking each Q-path direct current offset value as another preset direct current offset parameter, and performing direct current offset testing on the Q-path to obtain a second power measurement value corresponding to the Q-path direct current offset value;
the direct current offset parameter estimation unit is further configured to obtain a Q-path estimated intermediate value according to the I-path estimated intermediate value, all the Q-path direct current offset values, and second power measurement values corresponding thereto; obtaining an I path estimation value and a Q path estimation value according to the I path estimation intermediate value and the Q path estimation intermediate value; and the I path estimation value and the Q path estimation value form a direct current offset parameter.
8. The system according to claim 7, wherein the system comprises:
the pre-IQ distortion unit is further configured to use the IQ mismatch parameter as a first round of IQ mismatch parameter, and perform pre-IQ distortion on an initial baseband signal according to the first round of IQ mismatch parameter to obtain a first round of IQ corrected baseband signal;
the pre-dc offset unit is further configured to perform pre-dc offset on the first round of IQ-corrected baseband signals according to the first round of dc offset parameters to obtain first round of corrected baseband signals, where the first round of dc offset parameters are the dc offset parameters;
the IQ mismatch estimation module is further configured to use the baseband signal after the first round of correction as an initial baseband signal, perform IQ mismatch parameter estimation on the transmission path after the first round of correction again, and use an obtained IQ mismatch parameter as an IQ mismatch parameter of a second round;
the distortion parameter obtaining module is further configured to obtain a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter, and the second round IQ mismatch parameter.
9. The system according to claim 8, wherein the system comprises:
the pre-IQ distortion unit is further configured to perform pre-IQ distortion on the baseband signal after the first round of IQ correction according to a second round of IQ mismatch parameter to obtain a second round of IQ corrected baseband signal;
the direct current offset estimation module is further configured to use the baseband signal after the second round of IQ correction as a baseband signal after IQ correction, and perform direct current offset parameter estimation on a transmission path after the second round of IQ correction to obtain a second round of direct current offset parameter;
the distortion parameter obtaining module is further configured to obtain a signal distortion parameter according to the first round IQ mismatch parameter, the first round direct current offset parameter, the second round IQ mismatch parameter, and the second round direct current offset parameter.
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