CN115865594A - Passive intermodulation correction method and system based on FDD system - Google Patents

Abstract

The invention provides a passive intermodulation correction method and system based on an FDD system, and relates to the field of passive intermodulation correction. The method comprises the following steps: selecting sending signals on two carrier waves and sending the sending signals to a PIM distortion signal module together to obtain PIM interference signals on a receiving band; synthesizing the PIM interference signal and the receiving signal to obtain an interference receiving signal; carrying out delay compensation processing on the interference receiving signal to obtain a delay compensation receiving signal; sending the delay compensation receiving signal and the sending signal to a PIM estimation module to obtain an estimated PIM interference signal; an estimated received signal is derived based on the interfering received signal and the estimated PIM interfering signal. The system comprises an interference acquisition module, an interference synthesis module, an interference delay module, an interference estimation module and an interference correction module. By the simple passive intermodulation correction processing method, PIM signals can be corrected conveniently and quickly, and the receiving performance of a communication system is improved.

Description

A passive intermodulation correction method and system based on FDD system

technical field

The invention relates to the field of passive intermodulation correction, in particular to a passive intermodulation correction method and system based on an FDD system.

Background technique

With the increase of the amount of user data in the mobile communication system, the requirements for the throughput and data capacity of the communication system are also getting higher and higher, and there are many solutions for meeting the requirements in this respect. The most widely cited one today is the carrier aggregation technology (Carrier Aggregation, CA) introduced in LTE-A, that is, data is transmitted on multiple carriers. However, there are some passive devices in the radio frequency transceiver, such as duplexers, multiplexers, etc., which will introduce passive intermodulation (Passive Intermodulation, PIM). In some scenarios, the PIM signal will fall within the receiving frequency band, thus affecting the receiving performance.

That is to say, in the communication system, passive intermodulation interference refers to when two or more transmitting carriers pass through the same passive radio frequency transmission system, due to the influence of the nonlinearity of the transmission system, the baseband signal The phenomenon of non-linear frequency components resulting in interference, especially in the context of the prevalence of high-power multi-channel communication systems today, the PIM interference caused by the nonlinearity of various passive devices in the radio frequency system has an increasingly serious impact on the performance of reception. Therefore, there is an urgent need for a simple and quick method to correct the PIM signal at the receiving end to improve the receiving performance.

Contents of the invention

The purpose of the present invention is to provide a passive intermodulation correction method and system based on the FDD system. By proposing a simple passive intermodulation correction processing method, the PIM signal can be corrected conveniently and quickly. Improve the receiving performance of the communication system.

Embodiments of the present invention are achieved like this:

In the first aspect, an embodiment of the present application provides a passive intermodulation correction method based on an FDD system, including the following steps:

Select the transmission signals on the two carriers and send them to the PIM distortion signal module together to obtain the PIM interference signal on the receiving band;

Combining the PIM interference signal with the received signal to obtain the interfered received signal;

Perform delay compensation processing on the interference receiving signal to obtain the delay compensation receiving signal;

Send the delay compensation received signal and transmitted signal to the PIM estimation module to obtain an estimated PIM interference signal;

Based on the interfering received signal and the estimated PIM interfering signal, an estimated received signal is obtained.

In some embodiments of the present invention, the step of synthesizing the PIM interference signal and the received signal to obtain the interfered received signal specifically includes: adding the PIM interfered signal to the received signal to obtain the interfered received signal.

In some embodiments of the present invention, the expression of the above-mentioned estimated PIM interference signal is: y _PIM = αΦ, wherein, y _PIM is the estimated PIM interference signal, α is the PIM interference coefficient, and Φ is the fundamental matrix of the transmitted signal, based on random selection The transmitted signals on the two carriers of are obtained.

In some embodiments of the present invention, the PIM interference coefficient α is estimated based on the minimum mean square error.

其中，/>

为PIM干扰系数α的估计结果值，R为相关计算法则，表达式为：R_xx＝E{x·x^*}，R_yΦ为互相关函数，R_ΦΦ为自相关函数。In some embodiments of the present invention, the expression of the estimation result of the above-mentioned PIM interference coefficient α is:

where, />

is the estimated result value of PIM interference coefficient α, R is the correlation calculation rule, the expression is: R _xx =E{x·x ^* }, R _yΦ is the cross-correlation function, R _ΦΦ is the auto-correlation function.

In some embodiments of the present invention, the calculation process of the above-mentioned PIM interference coefficient α specifically includes:

Based on the transmitted signal and the received signal, the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ are repeatedly calculated to obtain multiple sets of corresponding correlation matrices;

The average value of the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ are obtained based on the correlation matrix respectively, which are recorded as the average value of the cross-correlation function R _yΦ and the average value of the autocorrelation function R _ΦΦ ;

Calculate the inverse matrix of the matrix corresponding to the autocorrelation function R _ΦΦ based on the average value of the autocorrelation function R _ΦΦ

与互相关函数R_yΦ平均值得到PIM干扰系数α的估计结果值。Based on inverse matrix

The estimated value of the PIM interference coefficient α is obtained by the average value of the cross-correlation function R _yΦ .

In the second aspect, an embodiment of the present application provides a passive intermodulation correction system based on an FDD system, which includes:

The interference acquisition module is used to select the transmission signals on the two carriers and send them into the PIM distortion signal module together to obtain the PIM interference signal on the receiving band;

The interference synthesis module is used to synthesize the PIM interference signal and the received signal to obtain the interfered received signal;

The interference delay module is used to perform delay compensation processing on the interference receiving signal to obtain the delay compensation receiving signal;

The interference estimation module is used to send the delay compensation received signal and the transmitted signal into the PIM estimation module to obtain an estimated PIM interference signal;

The interference correction module is used to obtain the estimated received signal based on the interfered received signal and the estimated PIM interfered signal.

In a third aspect, the embodiment of the present application provides an electronic device, which includes a memory for storing one or more programs; and a processor. When the above-mentioned one or more programs are executed by the above-mentioned processor, the above-mentioned method in any one of the above-mentioned first aspects is realized.

In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the method as described in any one of the above-mentioned first aspects is implemented.

Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects:

The present invention proposes a passive intermodulation correction method based on the FDD system, firstly selects the transmission signals on two carriers and sends them to the PIM distortion signal module together to obtain the PIM interference signal on the receiving band. This PIM interference signal is then added to the received signal to obtain a disturbed interfered received signal. Then, the interference received signal is subjected to delay compensation processing to obtain a delay-compensated received signal synchronous with the received signal. Then, the delay-compensated received signal and transmitted signal are sent to the PIM estimation module to obtain an estimated PIM interference signal, that is, an estimated PIM interference signal. Finally, the estimated PIM interference signal is removed from the interference received signal to obtain the final estimated received signal, and the passive intermodulation correction processing on the received signal is completed. The whole method is simple and clear, has low implementation difficulty, consumes less system memory resources, can conveniently and quickly implement correction processing on PIM signals, and improves the receiving performance of the communication system.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is a flow chart of an embodiment of a passive intermodulation correction method based on an FDD system in the present invention;

Fig. 2 is a flow chart of another embodiment of a passive intermodulation correction method based on an FDD system of the present invention;

Fig. 3 is the specific flowchart of the calculation process step of PIM interference coefficient α in the embodiment of the present invention;

Fig. 4 is a structural block diagram of an embodiment of a passive intermodulation correction system based on an FDD system in the present invention;

Fig. 5 is a structural block diagram of an electronic device provided by an embodiment of the present invention.

Icons: 1. Interference acquisition module; 2. Interference synthesis module; 3. Interference delay module; 4. Interference estimation module; 5. Interference correction module; 6. Memory; 7. Processor; 8. Communication interface.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments It is a part of the embodiments of this application, not all of them. The components of the embodiments of the application generally described and illustrated in the figures herein may be arranged and designed in a variety of different configurations.

Accordingly, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of the application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures. At the same time, in the description of the present application, the term "comprising", "comprising" or any other variation thereof is intended to cover a non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements, It also includes other elements not expressly listed, or elements inherent in the process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising said element.

Some implementations of the present application will be described in detail below in conjunction with the accompanying drawings. In the case of no conflict, each of the following embodiments and each feature in the embodiments can be combined with each other.

Example

Please refer to Figure 1 and Figure 2, the passive intermodulation correction method based on the FDD system includes the following steps:

Step S101: Select the transmission signals on the two carriers and send them together to the PIM distortion signal module to obtain the PIM interference signal on the reception band.

Most people have encountered noise or voice distortion during mobile phone calls, and even the inconvenience caused by sudden disconnection of the phone. Although we often blame these failures on the phone manufacturer or ISP for a poor signal in a particular location, sometimes these failures are caused by signal distortion generated by cell towers as one of the causes of this distortion It's PIM (passive intermodulation). Fundamentally speaking, PIM (Passive Intermodulation) is a process in a nonlinear device or propagation medium by the interaction of the spectral components of two or more input signals to generate new interference components whose frequency is equal to that of each input A linear combination of integer multiples of the signal component frequencies. If these new signals enter the receive band, they can interfere and distort the original signal passing between the two wireless systems. Any passive device will generate passive intermodulation products when more than one frequency is present in the device. Therefore, in order to ensure reliable communication performance, it is necessary to limit or eliminate PIM (passive intermodulation) distortion. In the above steps, since there is a loop delay between the received signal and the transmitted signal, it is necessary to perform synchronous processing on the received signal and the transmitted signal. That is to say, by selecting the transmission signals on two carriers and sending them to the PIM distortion signal module together, the PIM interference signal on the receiving band can be obtained, which can provide original data support for subsequent passive intermodulation correction processing.

Exemplarily, the selection of the transmission signals on the two carriers may be randomly selected, or may be selected according to the frequency used. The present invention does not limit the selection method, and the selection of the transmission signals on the two carriers shall prevail.

Step S102: Combining the PIM interference signal with the received signal to obtain an interference received signal.

In the above steps, the interference receiving signal is obtained by first synthesizing the PIM interference signal and the receiving signal, that is, the sending signal is first synthesized and added to the receiving signal, and then the estimated PIM interference signal is removed, so that the received signal can be detected Passive intermodulation correction.

Specifically, the step of combining the PIM interference signal with the received signal to obtain the interfered received signal specifically includes: adding the PIM interfered signal to the received signal to obtain the interfered received signal. That is to say, when synthesizing the PIM interference signal into the received signal, the simplest direct addition process can be used to obtain the received signal with the PIM interference signal added, and then simply directly subtract the corresponding estimated PIM Interference signal, will be able to achieve passive intermodulation correction of the received signal. Of course, other synthesis methods can also be used during synthesis, for example, the PIM interference signal is multiplied by an adjustment coefficient first and then added to the received signal. In this way, when the estimated PIM interference signal is subsequently removed, corresponding adjustments will also be performed. scaling.

Step S103: Perform delay compensation processing on the interference received signal to obtain a delay compensated received signal.

In the above steps, since there is a loop delay between the received signal and the transmitted signal, the interference received signal is subjected to delay compensation processing, which will enable the obtained delay compensation received signal to be synchronized with the received signal, thereby facilitating subsequent corrections deal with.

Step S104: Send the delay-compensated received signal and transmitted signal to the PIM estimation module to obtain an estimated PIM interference signal.

In the above steps, the synchronized delay-compensated received signal and transmitted signal are sent to the PIM estimation module to obtain the estimated PIM interference signal, that is, to obtain the estimated PIM interference signal of the system, so that the estimated PIM interference signal can be removed subsequently The PIM interference signal implements passive intermodulation correction processing on the received signal.

Specifically, the expression of the above estimated PIM interference signal is: y _PIM = αΦ, where y _PIM is the estimated PIM interference signal, α is the PIM interference coefficient, and Φ is the fundamental matrix of the transmitted signal. Based on the Send a signal to get it.

In the above steps, the fundamental matrix Φ of the transmitted signal can be obtained by acquiring the transmitted signals on the two selected carriers. If the signal models used are different, there will be different basis functions, which will not affect the subsequent processing. After constructing the above expression for estimating the PIM interference signal, α is the PIM interference coefficient, that is, the parameter to be estimated, so that the subsequent parameter estimation of the parameter α will obtain an accurate estimate of the PIM interference signal.

具体的原理可以是；利用长度N的两个发射信号构成矩阵Φ，y为对应长度的原始接收信号。对信号进行多次计算，每次计算长度为N的数据得到一组α的估计值，再对若干组估计值求平均值得到最终的估计结果，从而进行交调失真校正。该方案的运算复杂度很高，每次长度为N的信号运算都需要进行矩阵求逆，而对于某些较为复杂的信号模型，进行参数估计时其需要求逆的矩阵阶数较高，且需要多次计算，大大提升了算法实现的难度。In the prior art, the least squares (LS) estimation algorithm is usually used in signal estimation, and its LS-based α parameter estimation can be expressed as:

The specific principle may be: use two transmitted signals of length N to form a matrix Φ, and y is an original received signal of a corresponding length. Perform multiple calculations on the signal, each calculation of data with a length of N to obtain a set of estimated values of α, and then average several sets of estimated values to obtain the final estimated result, thereby performing intermodulation distortion correction. The calculation complexity of this scheme is very high. Each signal operation with a length of N needs to perform matrix inversion. For some more complex signal models, the order of the matrix that needs to be inverted is relatively high when performing parameter estimation, and Multiple calculations are required, which greatly increases the difficulty of algorithm implementation.

Correspondingly, in the embodiment of the present invention, the parameter estimation of the above-mentioned PIM interference coefficient α may be performed based on the minimum mean square error. The main idea is to use the correlation of signals for parameter estimation. Wherein, the interference signal in the received signal is correlated with the transmitted signal, while the non-interfering signal part in the received signal is not correlated with the transmitted signal.

其中，/>

为PIM干扰系数α的估计结果值，R为相关计算法则，表达式为：R_xx＝E{x·x^*}，R_yΦ为互相关函数，R_ΦΦ为自相关函数。Specifically, the expression of the estimation result of the PIM interference coefficient α when performing parameter estimation based on the minimum mean square error can be:

where, />

is the estimated result value of the PIM interference coefficient α, R is the correlation calculation rule, the expression is: R _xx =E{x·x ^* }, R _yΦ is the cross-correlation function, R _ΦΦ is the autocorrelation function.

In the above steps, by constructing the cross-correlation function of the estimated PIM interference signal and the fundamental matrix of the transmitted signal, and the autocorrelation function of the fundamental matrix of the transmitted signal, and then constructing the estimation result expression of the PIM interference coefficient α based on the two, the signal's Correlations are processed for parameter estimation.

Specifically, referring to FIG. 3, the calculation process of the above-mentioned PIM interference coefficient α specifically includes:

Step S201: Repeatedly calculating the cross-correlation function R _yΦ and the auto-correlation function R _ΦΦ based on the transmitted signal and the received signal, respectively, to obtain multiple sets of corresponding correlation matrices.

In the above steps, the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ are respectively calculated by using the transmitted and received signals with a length of N, and multiple sets of corresponding correlation matrices are obtained after repeated calculations, which can be used for subsequent corresponding processing Provide raw data support.

Step S202: Calculate the average value of the cross-correlation function R _yΦ and the auto-correlation function R _ΦΦ based on the correlation matrix respectively, which are recorded as the average value of the cross-correlation function R _yΦ and the average value of the auto-correlation function R _ΦΦ .

In the above steps, by performing averaging processing on the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ , the influence of white noise on the subsequent estimation results can be eliminated to a certain extent, making the subsequent calculation results more accurate and reliable.

Step S203: Calculate the inverse matrix of the matrix corresponding to the autocorrelation function R _ΦΦ based on the average value of the autocorrelation function R _ΦΦ

与互相关函数R_yΦ平均值得到PIM干扰系数α的估计结果值。Step S204: Based on the inverse matrix

The estimated value of the PIM interference coefficient α is obtained by the average value of the cross-correlation function R _yΦ .

然后将

与互相关函数R_yΦ平均值相乘将可以得到准确有效的PIM干扰系数α的估计结果值。In the above steps, the inverse matrix is obtained by inverting the matrix corresponding to the autocorrelation function R _ΦΦ

Then

Multiplying with the average value of the cross-correlation function R _yΦ can obtain an accurate and effective estimation result value of the PIM interference coefficient α.

In summary, compared to the least squares (LS) estimation algorithm commonly used in the prior art for estimation processing, the scheme in the above steps S201-S204 only needs to invert the matrix corresponding to the autocorrelation function R _ΦΦ once Comparing with the scheme based on the least squares estimation algorithm, it can greatly reduce the computational complexity and resource consumption. At the same time, by performing averaging processing on the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ , it can eliminate white space to a certain extent. The impact of noise on subsequent estimation results makes subsequent calculation results more accurate and reliable. That is to say, calculating the estimated value of the PIM interference coefficient α through the scheme in the above steps S201-S204 can simplify the calculation process and be easier to implement, and the system memory consumption is smaller and the anti-noise ability is stronger.

Step S105: Obtain an estimated received signal based on the interfered received signal and the estimated PIM interfered signal.

In the above steps, in the process of obtaining the estimated received signal, the estimated PIM interference signal (the estimated number of PIM interference signals that may be estimated) is removed from the received signal to which the PIM interference signal has been added (i.e. the interfering received signal), thereby An estimated received signal after passive intermodulation correction processing is obtained (that is, a received signal after correction processing is obtained). Of course, if the PIM interference signal and the received signal are synthesized to obtain the interfered received signal, then the estimated received signal is obtained based on the interfered received signal and the estimated PIM interfered signal, which is obtained by using the interfered received signal to subtract Estimate the PIM interference signal, so as to obtain the corresponding estimated received signal. Correspondingly, if other methods are used for combination processing during combination, the corresponding estimated received signal can be obtained by performing reverse processing of the combined process based on the interference received signal and the estimated PIM interference signal.

Based on the same inventive concept, please refer to Fig. 4, the present invention also proposes a passive intermodulation correction system based on the FDD system, including:

The interference acquisition module 1 is used to select the transmission signals on the two carriers and send them into the PIM distortion signal module together to obtain the PIM interference signal on the receiving band;

The interference synthesis module 2 is used to synthesize the PIM interference signal and the received signal to obtain the interfered received signal;

The interference delay module 3 is used to perform delay compensation processing on the interference receiving signal to obtain the delay compensation receiving signal;

The interference estimation module 4 is used to send the delay compensation received signal and the transmitted signal into the PIM estimation module to obtain an estimated PIM interference signal;

The interference correction module 5 is configured to obtain an estimated received signal based on the interfered received signal and the estimated PIM interfered signal.

For the specific implementation process of the above system, please refer to the passive intermodulation correction method based on the FDD system provided in the embodiment of the present application, which will not be repeated here.

Please refer to FIG. 5 . FIG. 5 is a structural block diagram of an electronic device provided by an embodiment of the present invention. The electronic device includes a memory 6, a processor 7 and a communication interface 8, and the memory 6, the processor 7 and the communication interface 8 are electrically connected to each other directly or indirectly to realize data transmission or interaction. For example, these components can be electrically connected to each other through one or more communication buses or signal lines. The memory 6 can be used to store software programs and modules, such as program instructions/modules corresponding to a passive intermodulation correction system based on an FDD system provided in the embodiment of the present application, and the processor 7 executes the software stored in the memory 6 Programs and modules to perform various functional applications and data processing. The communication interface 8 can be used for signaling or data communication with other node devices.

Wherein, memory 6 can be but not limited to, random access memory (Random Access Memory, RAM), read-only memory (Read Only Memory, ROM), programmable read-only memory (Programmable Read-OnlyMemory, PROM), erasable Read-only memory (Erasable Programmable Read-Only Memory, EPROM), Electric Erasable Programmable Read-Only Memory (EEPROM), etc.

The processor 7 may be an integrated circuit chip with signal processing capabilities. The processor 7 can be a general-purpose processor, including a central processing unit (Central Processing Unit, CPU), a network processor (NetworkProcessor, NP), etc.; it can also be a digital signal processor (Digital Signal Processing, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), Field-Programmable Gate Array (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

It can be understood that the structure shown in FIG. 5 is only for illustration, and the electronic device may also include more or less components than those shown in FIG. 5 , or have a configuration different from that shown in FIG. 5 . Each component shown in Fig. 5 may be implemented by hardware, software or a combination thereof.

In the embodiments provided in this application, it should be understood that the disclosed devices and methods may also be implemented in other ways. The device embodiments described above are only illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the architecture, functions and possible implementations of devices, methods and computer program products according to multiple embodiments of the present application. operate. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code that includes one or more Executable instructions. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. It should also be noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by a dedicated hardware-based system that performs the specified function or action , or may be implemented by a combination of dedicated hardware and computer instructions.

In addition, each functional module in each embodiment of the present application may be integrated to form an independent part, each module may exist independently, or two or more modules may be integrated to form an independent part.

If the above functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and other media that can store program codes. .

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

It will be apparent to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, but that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and not restrictive in all points of view, and the scope of the application is defined by the appended claims rather than the foregoing description, and it is intended that the scope of the present application be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in this application. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims (9)

1. A passive intermodulation correction method based on FDD system, is characterized in that, comprises the following steps: Select the transmission signals on the two carriers and send them to the PIM distortion signal module together to obtain the PIM interference signal on the receiving band; Combining the PIM interference signal with the received signal to obtain the interfered received signal; Perform delay compensation processing on the interference receiving signal to obtain the delay compensation receiving signal; Send the delay compensation received signal and transmitted signal to the PIM estimation module to obtain an estimated PIM interference signal; Based on the interfering received signal and the estimated PIM interfering signal, an estimated received signal is obtained. 2. A kind of passive intermodulation correction method based on FDD system as claimed in claim 1, it is characterized in that, described the step that obtains interference received signal by combining PIM interference signal and receiving signal specifically comprises: PIM interference signal Added to the received signal to obtain an interfering received signal. 3. A kind of passive intermodulation correction method based on FDD system as claimed in claim 1, is characterized in that, the expression of described estimated PIM interference signal is: y _PIM =αΦ, wherein, y _PIM is estimated PIM Interference signal, α is the PIM interference coefficient, Φ is the fundamental matrix of the transmitted signal, which is obtained based on the transmitted signals on two randomly selected carriers. 4. A kind of passive intermodulation correction method based on FDD system as claimed in claim 3, is characterized in that, described PIM interference coefficient α carries out parameter estimation based on minimum mean square error. 5. a kind of passive intermodulation correction method based on FDD system as claimed in claim 3, is characterized in that, the estimation result expression of described PIM interference coefficient α is:

where, />

is the estimated result value of PIM interference coefficient α, R is the correlation calculation rule, the expression is: R _xx =E{x·x ^* }, R _yΦ is the cross-correlation function, R _ΦΦ is the auto-correlation function. 6. A kind of passive intermodulation correction method based on FDD system as claimed in claim 5, is characterized in that, the calculation process of described PIM interference coefficient α specifically comprises: Based on the transmitted signal and the received signal, the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ are repeatedly calculated to obtain multiple sets of corresponding correlation matrices; The average value of the cross-correlation function R _yΦ and the autocorrelation function R _ΦΦ are obtained based on the correlation matrix respectively, which are recorded as the average value of the cross-correlation function R _yΦ and the average value of the autocorrelation function R _ΦΦ ; Calculate the inverse matrix of the matrix corresponding to the autocorrelation function R _ΦΦ based on the average value of the autocorrelation function R _ΦΦ

Based on inverse matrix

The estimated value of the PIM interference coefficient α is obtained by the average value of the cross-correlation function R _yΦ . 7. A passive intermodulation correction system based on an FDD system, characterized in that it comprises: The interference acquisition module is used to select the transmission signals on the two carriers and send them into the PIM distortion signal module together to obtain the PIM interference signal on the receiving band; The interference synthesis module is used to synthesize the PIM interference signal and the received signal to obtain the interfered received signal; The interference delay module is used to perform delay compensation processing on the interference receiving signal to obtain the delay compensation receiving signal; The interference estimation module is used to send the delay compensation received signal and the transmitted signal into the PIM estimation module to obtain an estimated PIM interference signal; The interference correction module is used to obtain the estimated received signal based on the interfered received signal and the estimated PIM interfered signal. 8. An electronic device, characterized in that it comprises: memory for storing one or more programs; processor; When the one or more programs are executed by the processor, the method according to any one of claims 1-6 is realized. 9. A computer-readable storage medium, on which a computer program is stored, wherein, when the computer program is executed by a processor, the method according to any one of claims 1-6 is implemented.

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