Closed-loop shortwave communication method, device, equipment and readable storage medium

Abstract

The present application provides a short-wave communication method, apparatus, device and readable storage medium based on a closed loop. Each time the electronic device sends a baseband signal, the current pre-distortion model is used to pre-distort the baseband information to obtain a distorted signal, and the pre-distortion coefficient is determined by the distorted signal and the current pre-distortion model is updated to obtain a new pre-distortion model, so that the baseband signal can be pre-distorted when a new baseband signal is sent next time. With this solution, for electronic devices with a feedback loop and abundant FPGA resources, by updating the pre-distortion model in real time, the nonlinearity of the short-wave power amplifier can be tracked to a great extent, and the nonlinearity of the power amplifier can be compensated in time.

Description

Technical Field

[0001] The present application relates to the field of digital predistortion technology in the field of shortwave communication technology, and in particular to a shortwave communication method, device, equipment and readable storage medium based on a closed loop. Background Art

[0002] Shortwave communication mainly relies on sky wave transmission, which has the characteristics of long transmission distance and no need for relaying. It is an important means of modern communication.

[0003] At present, there are many kinds of losses in the shortwave communication process, which will weaken the received power of the signal. In order to increase the transmission distance of shortwave communication, it is necessary to increase the transmission power of the transmitting device. The power amplifier at the transmitting end is a typical nonlinear system. When the transmission power of the transmitting device is close to saturation, the output will show nonlinear characteristics, resulting in nonlinear effects such as spurious and intermodulation distortion, which will increase the bit error rate of the communication system and interfere with adjacent channels. Therefore, shortwave communication has very high requirements for the linearity of the power amplifier. In order to improve the linearity of the power amplifier, the power back-off method is usually used, that is, the input power of the power amplifier is backed off from the 1 decibel (dB) compression point by several dB, so that the power amplifier works in an area far away from the 1dB compression point, so that the power amplifier returns to the linear amplification area.

[0004] However, the power back-off method reduces the utilization efficiency of the power amplifier and increases heat dissipation. Summary of the invention

[0005] The embodiments of the present application provide a closed-loop shortwave communication method, apparatus, device and readable storage medium, which utilize a closed-loop feedback mechanism to compensate for the nonlinearity of a power amplifier while ensuring the efficiency of the power amplifier.

[0006] In a first aspect, an embodiment of the present application provides a shortwave communication method based on a closed loop, which is applied to an electronic device, including:

[0007] Performing predistortion processing on the first baseband signal using a first predistortion model to obtain a first distorted signal;

[0008] updating the first predistortion model according to the first distortion signal to obtain a second predistortion model;

[0009] Using the second predistortion model to perform predistortion processing on the second baseband signal to obtain a second distorted signal, wherein the first baseband signal and the second baseband signal are signals transmitted twice by the transmitter of the electronic device;

[0010] Shortwave communication is performed according to the second distorted signal.

[0011] In a second aspect, an embodiment of the present application provides a shortwave communication device based on a closed loop, comprising:

[0012] A predistortion module, configured to perform predistortion processing on the first baseband signal using a first predistortion model to obtain a first distorted signal;

[0013] An updating module, configured to update the first pre-distortion model according to the first distortion signal to obtain a second pre-distortion model;

[0014] The predistortion module is further used to perform predistortion processing on the second baseband signal using the second predistortion model to obtain a second distorted signal, wherein the first baseband signal and the second baseband signal are signals transmitted twice successively by the transmitter of the electronic device;

[0015] A communication module is used to perform shortwave communication according to the second distorted signal.

[0016] In a third aspect, an embodiment of the present application provides an electronic device, comprising: a processor, a memory, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the electronic device implements the above-mentioned shortwave communication method based on a closed loop.

[0017] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer instructions are stored. When the computer instructions are executed by a processor, they are used to implement the above-mentioned closed-loop based shortwave communication method.

[0018] In a fifth aspect, an embodiment of the present application provides a computer program product comprising a computing program, and when the computer program is executed by a processor, the closed-loop-based shortwave communication method as described above is implemented.

[0019] The embodiments of the present application provide a short-wave communication method, apparatus, device and readable storage medium based on a closed loop. Each time the electronic device sends a baseband signal, the current pre-distortion model is used to pre-distort the baseband information to obtain a distorted signal, and the pre-distortion coefficient is determined by the distorted signal and the current pre-distortion model is updated to obtain a new pre-distortion model, so that the baseband signal can be pre-distorted when a new baseband signal is sent next time. With this solution, for electronic devices with a feedback loop and abundant FPGA resources, by updating the pre-distortion model in real time, the nonlinearity of the short-wave power amplifier can be tracked to a great extent, and the nonlinearity of the power amplifier can be compensated in time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0021] Figure 1A is a schematic diagram of an AM-AM characteristic curve of a shortwave power amplifier of an electronic device for executing the method provided in an embodiment of the present application;

[0022] Figure 1B is a schematic diagram of an AM-PM characteristic curve of a shortwave power amplifier of an electronic device for executing the method provided in an embodiment of the present application;

[0023] Figure 2 It is a basic principle diagram of the closed-loop shortwave communication method provided in an embodiment of the present application;

[0024] Figure 3 It is a schematic diagram of the connection structure of a transmitter and a predistortion-related part of an electronic device for performing a closed-loop-based shortwave communication method;

[0025] Figure 4 is a flow chart of a closed-loop shortwave communication method provided in an embodiment of the present application;

[0026] Figure 5 is another flow chart of the closed-loop shortwave communication method provided in an embodiment of the present application;

[0027] Figure 6 It is a structural schematic diagram of a first predistortion model in an electronic device for executing the closed-loop based shortwave communication method provided in an embodiment of the present application;

[0028] Figure 7 Characteristic curve diagrams of fractional alignment and non-fractional alignment in the closed-loop shortwave communication method provided in an embodiment of the present application;

[0029] Figure 8 It is a block diagram of the internal structure of FPGA in the closed-loop shortwave communication method provided in an embodiment of the present application;

[0030] Fig. 9 It is a rendering of a closed-loop shortwave communication method provided in an embodiment of the present application;

[0031] Fig.10 A schematic diagram of the structure of a shortwave communication device based on a closed loop provided in an embodiment of the present application;

[0032] Fig.11 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] It should be noted that the terms "including" and "having" and any variations thereof in the embodiments of the present application and the accompanying drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0035] At present, electronic devices based on shortwave communication have strict requirements on power consumption. Low power consumption is an inevitable trend in the development of electronic devices. In order to reduce the power consumption of electronic devices, it is necessary to improve the working efficiency of the power amplifier so that the transmitter of the electronic device has lower input power consumption under the premise of the same output power. The shortwave power amplifier (hereinafter referred to as the power amplifier or power amplifier) ​​is the core component of the shortwave transmission link. The performance of the power amplifier has a significant impact on the overall effect of the electronic equipment, intermodulation distortion and other indicators.

[0036] In order to improve the efficiency of the power amplifier, the power amplifier of the transmitter is usually required to work in a state close to saturation. Although this method can increase the output power of the electronic device under the same input power, the closer the power amplifier works to the saturation point, the stronger the nonlinear characteristics of the power amplifier will be, and the greater the nonlinear distortion of the power amplifier output signal will be. The nonlinear distortion of the signal will not only produce in-band distortion, affecting the signal bit error rate, but also produce out-of-band distortion, causing interference to adjacent frequency band channels.

[0037] Therefore, shortwave communication places very high demands on the linearity of the power amplifier of electronic equipment. It is extremely important to improve the linearity of the power amplifier while maintaining high efficiency. Power amplifier linearization technology is called a key technology in shortwave communication systems.

[0038] In order to improve the linearity of the power amplifier, the traditional method is power back-off, that is, to back off the input power of the power amplifier from the 1dB compression point by several dB, so that the power amplifier works in an area far away from the 1dB compression point, thereby making the power amplifier work in the linear amplification area.

[0039] However, the power back-off method reduces the utilization efficiency of the power amplifier and increases heat dissipation. This method of sacrificing the efficiency of the power amplifier in exchange for linearity is obviously undesirable. Moreover, when the power is backed off to a certain extent, the linearity of the power amplifier cannot be changed. Therefore, the power back-off method is not suitable for shortwave communication systems that have high requirements for both linearity and efficiency of the power amplifier.

[0040] In addition, there are some other power amplifier linearization technologies in the industry, such as Doherty power amplifier technology, feedforward technology, digital pre-distortion technology, etc. Among them, Doherty power amplifier technology requires additional hardware overhead. The circuit characteristic parameters of feedforward technology are affected by device aging and temperature changes, and the performance is unstable. In addition, the efficiency of feedforward technology is low, generally around 10%, and the design and debugging are relatively complicated. Digital pre-distortion technology can improve the nonlinearity of the power amplifier by changing the baseband signal waveform without reducing the working efficiency of the shortwave power amplifier.

[0041] Based on this, the embodiments of the present application provide a closed-loop shortwave communication method, device, electronic device and readable storage medium based on digital pre-distortion theory, which utilizes a closed-loop feedback mechanism to compensate for the nonlinearity of the power amplifier while ensuring the efficiency of the power amplifier.

[0042] This solution is suitable for scenarios with complex and changing usage scenarios that require tracking and compensation of the power amplifier. This solution requires that the transmitter of the electronic device has a feedback loop and sufficient field programmable gate array (FPGA) resources. In this way, the nonlinearity of the power amplifier can be tracked to the greatest extent and compensated.

[0043] Figure 1A Schematic diagram of the AM-AM characteristic curve of the shortwave power amplifier of the electronic device used to execute the method provided in the embodiment of the present application. Figure 1A , the horizontal axis represents input amplitude modulation (AM), and the vertical axis represents output AM. The input AM and output AM are nonlinear.

[0044] Figure 1B Schematic diagram of the AM-PM characteristic curve of the shortwave power amplifier of the electronic device used to execute the method provided in the embodiment of the present application. Figure 1A The horizontal axis represents input AM, and the vertical axis represents output phase modulation (PM). The input AM and output PM are nonlinear.

[0045] The technical concept of the embodiment of the present application is to construct a digital pre-distortion (DPD) model that is opposite to the characteristics of a shortwave power amplifier. The digital pre-distortion model is also called a pre-distortion model or a DPD model. After the baseband signal is input into the pre-distortion model, the pre-distortion model changes the baseband signal into a distorted signal, and then the distorted signal is input into the shortwave power amplifier, so that the output signal of the shortwave power amplifier forms a linear relationship with the original baseband signal. Among them, the pre-distortion model can also be called a pre-distorter.

[0046] Ideally, the cascaded system of "predistortion-power amplifier" exhibits linear characteristics. For example, please refer to Figure 2 .

[0047] Figure 2 This is a basic principle diagram of the closed-loop shortwave communication method provided by the embodiment of the present application. Figure 2 , the upper left corner coordinate system represents the pre-distortion model, that is, the characteristic curve of the DPD model. The input of this characteristic curve (V i ) and output (V d ) is nonlinear. The coordinate system in the upper right corner represents the characteristic curve of the power amplifier (PA). The input (v d ) and output (V0) are also non-linear.

[0048] The bottom coordinate system represents the characteristic curve of the cascade model composed of the pre-distortion model and the PA. The input of the characteristic curve (V i ) and output (V0) are linearly related.

[0049] based on Figure 1A , Figure 1B and Figure 2 In order to solve the nonlinear problem of the power amplifier, based on the basic theory of pre-distortion, the purpose of the embodiment of the present application is to provide a shortwave communication method, device, electronic device and readable storage medium based on a closed loop. The shortwave communication device based on a closed loop can be flexibly built into the shortwave digital channel unit of the electronic device, which is easy to install and easy to implement. Moreover, by adopting the method described in the embodiment of the present application, after adopting the pre-distortion processing technology, the third-order intermodulation index (2MHz-30MHz) of the transmitter of the electronic device is improved from the original -20dB to more than -40dB, and the spectrum quality of the transmitter is also greatly improved.

[0050] Figure 3 This is a schematic diagram of the connection structure of the transmitter and predistortion related parts of the electronic device for implementing the closed-loop shortwave communication method. Figure 3, the connection structure includes a digital domain and an analog domain. The baseband signals transmitted twice by the transmitter of the electronic device are called the first baseband signal and the second baseband signal. When transmitting the first baseband signal x(n), the predistortion model is the first predistortion model, and the predistortion coefficient of the first predistortion model is called the first predistortion coefficient. During the signal transmission process, the first baseband signal x(n) is predistorted by the first predistortion model to obtain the first distortion signal z(n). After that, the update parameter, i.e., the second predistortion coefficient, is determined according to the first distortion signal z(n), and the first predistortion model is updated by the second predistortion coefficient to obtain the second predistortion model. In the process of determining the second predistortion coefficient, the first distortion signal is up-converted to radio frequency to obtain a radio frequency signal. The radio frequency signal is sent out after a series of processing such as digital-to-analog conversion and power amplification in the analog domain. At the same time, a part of the signal is fed back to the digital domain through a coupling loop in the analog domain, and the second predistortion coefficient is determined in the digital domain according to the feedback signal and the first distortion signal to update the first predistortion model.

[0051] When transmitting the second baseband signal, the electronic device uses the second predistortion model to perform predistortion processing on the second baseband signal to obtain a second distorted signal. The distorted signal is used to continue to determine new predistortion coefficients and update the predistortion model, thereby tracking the nonlinearity of the power amplifier to the greatest extent and compensating for the nonlinearity of the power amplifier.

[0052] Below, based on Figure 2 The basic principles and Figure 3 The connection structure shown is used to describe in detail the closed-loop shortwave communication method described in the embodiment of the present application. For example, please refer to Figure 4 .

[0053] Figure 4 This is a flow chart of a closed-loop shortwave communication method provided by an embodiment of the present application. The execution subject of this embodiment is an electronic device that uses shortwave for communication, and the method includes the following steps:

[0054] 401. Perform predistortion processing on a first baseband signal by using a first predistortion model to obtain a first distorted signal.

[0055] In the embodiment of the present application, the first baseband signal is the first baseband signal sent by the emitter of the electronic device between two adjacent baseband signals, and the second baseband signal is the signal sent by the electronic device after sending the first baseband signal. The first baseband signal may be the baseband signal sent for the first time after the electronic device is started, in which case the second baseband signal is the signal sent for the second time by the electronic device. In addition, the first baseband signal may not be the signal sent for the first time, for example, the first baseband signal is the signal sent for the 49th time after the electronic device is started, and the second baseband signal is the signal sent for the 50th time after the electronic device is started.

[0056] The predistortion coefficient of the first predistortion model is the first predistortion coefficient. The electronic device uses the first predistortion model to perform predistortion compensation on the first baseband signal to obtain a first distorted signal.

[0057] 402. Update the first pre-distortion model according to the first distortion signal to obtain a second pre-distortion model.

[0058] Exemplarily, please refer to FIG. 1, the electronic device determines the second predistortion coefficient according to the first distortion signal, and uses the second predistortion coefficient to update the first predistortion model to obtain the second predistortion model. In the process of determining the second predistortion coefficient, the first distortion signal is up-converted to radio frequency to obtain a radio frequency signal. The radio frequency signal is sent out after a series of processing such as digital-to-analog conversion and power amplification in the analog domain. At the same time, a part of the signal is fed back to the digital domain through a coupling loop in the analog domain, and the second predistortion coefficient is determined in the digital domain according to the feedback signal and the first distortion signal to update the first predistortion model.

[0059] 403. Perform predistortion processing on a second baseband signal using the second predistortion model to obtain a second distorted signal, wherein the first baseband signal and the second baseband signal are signals transmitted twice successively by a transmitter of the electronic device.

[0060] When the electronic device sends the second baseband signal, the updated predistortion model, that is, the second predistortion model, is used to perform predistortion processing on the second baseband signal to obtain a second distorted signal.

[0061] 404. Perform shortwave communication according to the second distorted signal.

[0062] After obtaining the second distorted signal, the electronic device performs up-conversion, digital-to-analog conversion, power amplification, harmonic filtering, etc. on the second distorted signal and outputs it. At the same time, a new feedback signal is obtained according to the second distorted signal, and the second pre-distortion model is continuously updated using the feedback signal, so that the updated pre-distortion model is used to process the baseband signal when the baseband signal is transmitted next time.

[0063] The closed-loop shortwave communication method provided by the embodiment of the present application is that each time the electronic device sends a baseband signal, the current predistortion model is used to predistort the baseband information to obtain a distorted signal, and the predistortion coefficient is determined by the distorted signal and the current predistortion model is updated to obtain a new predistortion model, so that the baseband signal can be predistorted and compensated when a new baseband signal is sent next time. With this solution, for electronic devices with a feedback loop and abundant FPGA resources, the nonlinearity of the shortwave power amplifier can be tracked to a great extent by updating the predistortion model in real time, and the nonlinearity of the power amplifier can be compensated in time.

[0064] Optionally, in the above embodiment, in the process of the electronic device updating the first pre-distortion model according to the first distortion signal to obtain the second pre-distortion model, first, a feedback signal is determined according to the first distortion signal. Thereafter, a correlation coefficient is determined according to the first baseband signal and the feedback signal. When the correlation coefficient is greater than a preset threshold, the first pre-distortion model is updated according to the first distortion signal to obtain the second pre-distortion model.

[0065] Exemplarily, the electronic device up-converts the first distorted signal to radio frequency to obtain a radio frequency signal. The radio frequency signal is processed in the analog domain such as digital-to-analog conversion, power amplification, harmonic filtering, etc. and then output. At the same time, the partially processed radio frequency signal is down-converted to obtain a down-converted baseband signal, which is also referred to as a feedback signal. Afterwards, the electronic device determines whether to update the first pre-distortion model based on the first baseband signal and the feedback signal. If the first pre-distortion model is updated, it is necessary to determine the second pre-distortion coefficient, and use the second pre-distortion coefficient to update the first pre-distortion model to obtain the second pre-distortion model. If the first pre-distortion model is not updated, it means that there is no need to update the first pre-distortion model, and the first pre-distortion model continues to be used during the process of sending the second baseband signal.

[0066] When the electronic device determines whether to update the first pre-distortion model according to the first baseband signal and the feedback signal, the electronic device determines a correlation coefficient according to the first baseband signal and the feedback signal. If the correlation coefficient is greater than a preset threshold, the first pre-distortion model is updated; if the correlation coefficient is less than or equal to the preset threshold, the first pre-distortion model is continued to be used when sending the second baseband signal.

[0067] By adopting this solution, the nonlinearity of the first predistortion signal predistorted by the first predistortion model is evaluated through the feedback signal, and whether to update the first predistortion model is determined according to the evaluation result, which can effectively reduce the calculation complexity and save calculation time.

[0068] Figure 5 is another flow chart of the shortwave communication method based on closed loop provided by the embodiment of the present application. The execution subject of this embodiment is an electronic device that uses shortwave for communication. Figure 3 , Figure 5 The steps include:

[0069] 501. Perform predistortion processing on a first baseband signal by using a first predistortion model to obtain a first distorted signal.

[0070] Exemplarily, the electronic device obtains the first predistortion coefficient in advance, and obtains the first predistortion model based on the first predistortion coefficient in advance. For example, when the electronic device is initially started, the first predistortion coefficient is 0. For another example, the first electronic device has sent other baseband signals before sending the first baseband signal, then the first predistortion coefficient is determined by the electronic device according to feedback signals corresponding to the other baseband signals.

[0071] When transmitting the first baseband signal, the electronic device uses the pre-obtained first predistortion coefficient and the first predistortion model to perform predistortion compensation on the first baseband signal to obtain a first distorted signal.

[0072] Afterwards, the electronic device updates the first pre-distortion model according to the first distortion signal to obtain a second pre-distortion model. During the updating process, the feedback signal is determined according to the first distortion signal, as shown in steps 502-505. Then, the electronic device aligns the first distortion signal and the feedback signal, as shown in step 506; then, the correlation coefficient is calculated, as shown in step 507. When the correlation coefficient is greater than a preset threshold, the first pre-distortion model is updated according to the first distortion signal to obtain a second pre-distortion model.

[0073] The process of the electronic device determining the feedback signal according to the first distorted signal is shown in the following step 502.

[0074] 502. Up-convert the first distorted signal to a radio frequency domain to obtain a radio frequency signal.

[0075] Please refer to 3 at the same time. The electronic device sends the pre-distortion compensated baseband signal, i.e., the first distorted signal, to the digital up converter (DUC) module to achieve the purpose of up-converting the pre-distortion compensated first baseband signal to the RF domain. In other words, after the first distorted signal passes through the up-conversion module, an RF signal is obtained. The RF signal is also called an RF digital signal. By up-converting the distorted first distorted signal to the RF frequency band required for shortwave, the obtained RF signal can be transmitted in the atmosphere.

[0076] 503. Perform digital-to-analog conversion on the radio frequency signal to obtain an analog signal, and amplify the power of the analog signal to obtain an amplified signal.

[0077] For example, please refer to Figure 3 In the analog domain, digital-analog (DA) conversion modules, power amplifiers, harmonic filters, directional couplers, and analog-to-digital conversion modules are set up.

[0078] The electronic device converts the up-converted RF signal into an analog signal through a digital-to-analog conversion module. After that, the electronic device sends the analog signal obtained through the digital-to-analog conversion to a power amplifier for power amplification, thereby obtaining an amplified signal.

[0079] 504. Perform harmonic filtering on the amplified signal to obtain a filtered signal.

[0080] The electronic device sends the amplified signal obtained after the power amplifier to the harmonic filter to filter out the harmonic distortion at the harmonic position generated by the power amplifier to reduce the nonlinear effect of the harmonic distortion on the RF signal. After harmonic filtering, the filtered signal is obtained, which is also called the filtered RF signal.

[0081] 505. The filtered RF signal is output through the output port of the directional coupler as the output of the power amplifier, and the forward coupling port of the directional coupler outputs the RF signal and down-converts it to a baseband signal.

[0082] Exemplarily, a portion of the filtered signal passes through a directional coupler as the output of the power amplifier, and another small amount of the filtered signal is converted into a digital signal and then passes through a digital down converter (DDC) module to obtain a baseband signal. The baseband signal obtained by down conversion is also called a feedback signal.

[0083] In the specific implementation process, the directional coupler is used to divide the power of the input filtered signal according to a certain percentage, and most of the filtered signal is used as the output of the power amplifier, and less filtered signal is coupled to the candidate analog-to-digital conversion module. The coupling ratio of the directional coupler is, for example, 999:1, 998:2, 990:10, etc., which is not limited in the embodiments of the present application.

[0084] 506. The electronic device aligns the feedback signal and the first distorted signal.

[0085] Please refer to Figure 3 The input of the delay alignment module includes a feedback signal and a first distorted signal. The electronic device uses the delay alignment module to align the feedback signal and the first distorted signal obtained by down-conversion, thereby removing the influence of distortion caused by signal delay.

[0086] 507. Determine a correlation coefficient between the first baseband signal and the feedback signal, compare the correlation coefficient with a preset threshold, and if the correlation coefficient is greater than the preset threshold, execute step 508; if the correlation coefficient is less than or equal to the preset threshold, execute step 510.

[0087] Please also refer to Figure 3The digital domain is provided with a coefficient update control module, which calculates the correlation coefficient between the first baseband signal and the feedback signal. In addition, the coefficient update control module also transmits the feedback signal and the fractionally aligned distorted signal to the LS estimation module.

[0088] The coefficient update control module integrates the nonlinear parameters required by the power amplifier according to certain weights and certain scores, merges them into a correlation coefficient, and compares the correlation coefficient with a preset threshold. When the correlation coefficient is greater than the preset threshold, the LS estimation module is enabled to calculate the second predistortion coefficient.

[0089] 508. The electronic device determines a predistortion coefficient of a second predistortion model according to the aligned first predistortion signal and the feedback signal, and uses the predistortion coefficient to update the first predistortion model to obtain a second predistortion model.

[0090] For example, please refer to Figure 3 , a least squares (LS) estimation module is provided in the digital domain, and the input of the LS estimation module includes an enable signal, an aligned first predistortion signal, and a feedback signal. Assuming that the enable signal is 1, indicating that the correlation coefficient is greater than a preset threshold, the LS module performs LS estimation on the aligned first predistortion signal and the feedback signal, thereby obtaining a predistortion coefficient of a second predistortion model, and inputs the predistortion coefficient into the predistortion module, and uses the predistortion coefficient to update the first predistortion model, thereby obtaining a second predistortion model.

[0091] 509. Predistort the second baseband signal using a second predistortion model.

[0092] Exemplarily, after the second pre-distortion model is obtained, the subsequently input baseband signal, ie, the second baseband signal, will be pre-distortion compensated based on the second pre-distortion model.

[0093] 510. Perform predistortion processing on the second baseband signal using the first predistortion model.

[0094] Exemplarily, assuming that the enable signal is 0, it indicates that the correlation coefficient is less than or equal to a preset threshold, which means that there is no need to update the first pre-distortion model, and the first pre-distortion model is continuously used to compensate the second baseband signal.

[0095] By adopting this solution, the electronic device performs up-conversion, digital-to-analog conversion, amplification, harmonic filtering, etc. on the first distorted signal to output and obtain a feedback signal, thereby ensuring the output power while obtaining the feedback signal to prepare for the subsequent update of the first pre-distortion model.

[0096] Optional, above Figure 5 In the illustrated embodiment, in step 501, the expression of the first pre-distortion model is shown in the following formula (1):

[0097]

[0098] Wherein, x(n) represents the first baseband signal, that is, the input signal of the first predistortion model. a represents the predistortion coefficient of the first predistortion model. n represents the sampling number of the signal, and M is a memory polynomial, which is used to characterize the memory characteristics of the power amplifier, indicating that the output of the power amplifier is related to the first m symbols of the input signal. K is the nonlinear characteristic characterized by the memory polynomial. Considering that shortwave power amplifiers may have memory characteristics in addition to the commonly existing nonlinear characteristics, the first predistortion model needs to compensate for the memory characteristics of the power amplifier, so a memory term is added. The orders of M and K are preset. When m>0, k>0, all a are mk Initialized to 0; when m = 0, k = 0, a 00 =1.

[0099] By writing formula (1) in matrix form, we get the following formula (2):

[0100] z=XA formula (2)

[0101] In formula (2), X represents the input vector matrix of the first predistortion model, and A represents the predistortion coefficient matrix of the first predistortion model.

[0102] The expressions of X and A are shown in the following formula (3):

[0103] Z=[z(n),…,z(n)|z(n)| K ,…,z(nM),…,z(nM)|z(nM)| K ]

[0104] A=[a 00 ,…,a 0K ,…,a M0 ,…,a MK ]Formula (3)

[0105] Figure 6 It is a structural schematic diagram of a first pre-distortion model in an electronic device for executing the closed-loop based shortwave communication method provided in an embodiment of the present application.

[0106] Please refer to Figure 6 , the first predistortion model is a 5th order model, and the input of the model includes the predistortion coefficient and the first baseband signal. The predistortion coefficient is the coefficient in the figure, and the first baseband signal is divided into two signals, one of which is delayed by one clock cycle, so that the first predistortion model obtains a memory item. The delay is as shown in the figure Z -1 As shown, the memory term is shown as M1 in the figure. Another signal reaches M0, and the expansion of M0 is shown in the polynomial model on the right.

[0107] The input of the polynomial model is the first baseband signal and the predistortion coefficient. After taking the absolute value of the input first baseband signal, the first power, the second power, the third power and the fourth power of the absolute value are calculated to obtain four powers. After that, each "power" obtained is multiplied by the input first baseband signal itself to obtain multiple products. The multiple products and the first baseband signal itself have a total of 5 data. After obtaining 5 data, each data is further multiplied by the predistortion coefficient to obtain the output of M0.

[0108] The input of M1 is delayed by one cycle compared to M0. The predistortion coefficient of M1 is another set of coefficients. The sum of the output of M0 and the output of M1 constitutes the output of the predistortion model.

[0109] Figure 8 In the example, the predistortion coefficients are expressed as [a0, a1, a2, a3, a4]. For M0, the predistortion coefficients are, for example, [a 00 ,a 01 ,a 02 ,a 03 ,a 04 ], the predistortion coefficient of M1 is, for example, [a 10 ,a 11 ,a 12 ,a 13 ,a 14 ].

[0110] Optionally, in an embodiment of the present application, the delay alignment in the above step 506 includes integer alignment and fractional alignment. That is, in the above step 506, when the electronic device aligns the first pre-distortion signal and the feedback signal, first, the feedback signal is used as a reference signal, and integer delay alignment is performed on the first distorted signal to obtain an integer-aligned distorted signal. Afterwards, the electronic device uses the feedback signal as a reference signal and performs fractional delay alignment on the integer-aligned distorted signal to obtain a fractionally-aligned distorted signal.

[0111] Exemplarily, during the integer alignment process, the electronic device uses one signal as a reference and performs a shift operation on another signal that needs to be aligned, and the minimum unit of the shift operation is the sampling period of the signal. For example, the electronic device uses the feedback signal f(n) as the base station signal and the first distorted signal z(n) as the signal that needs to be aligned. During the alignment process, the electronic device performs a correlation operation on the two signals and obtains the number corresponding to the maximum value. The expression of integer alignment is shown in the following formula (4):

[0112]

[0113] In formula (4), N represents the total number of signal points, P represents the integer delay, and the superscript "*" represents the conjugate operation. After obtaining the value of the integer delay P, the first distorted signal z(n) is shifted to obtain the integer-aligned distorted signal z', as shown in the following formula (5):

[0114] z′=[z(NP:N),z(1:NP-1)]Formula (5)

[0115] Since only integer alignment cannot align the first distorted signal and the feedback signal to a satisfactory degree, a delay error of less than a sampling unit time remains. Therefore, in the embodiment of the present application, fractional alignment is performed on the basis of integer alignment, and a fractional level alignment operation is also required.

[0116] In the fractional alignment process, the integer-aligned distorted signal z' undergoes Fourier transform and its phase is aligned in the frequency domain, as shown in the following formula (6):

[0117]

[0118] In formula (6), the range of q is as shown in formula (7):

[0119]

[0120] Where Q represents the fractional delay, F * (e jw ) represents the frequency domain expression of the conjugate of the feedback signal f(n) after Fourier transform, Z′(e jw ) represents the expression of z′ in the frequency domain after Fourier transform, and Fac represents the fractional delay accuracy, which represents the total number of fractional delay shifts within one time unit.

[0121] After the fractional delay is obtained according to formula (7), the corresponding shift operation is performed on the integer-aligned distortion signal z' to obtain data for establishing the second pre-distortion model, that is, the fractionally aligned distortion signal z", as shown in the following formula (8):

[0122]

[0123] Figure 7 The following are characteristic curves of the closed-loop shortwave communication method provided in an embodiment of the present application after and without fractional alignment.

[0124] Please refer to Figure 7 , the gray represents the characteristic curve of the first distorted signal after only integer alignment, and the black represents the characteristic curve after adding fractional alignment on the basis of integer alignment. Figure 7It can be seen that after the delay alignment, the divergence of the characteristic curve can be reduced, thereby reducing the complexity of obtaining the second pre-distortion model.

[0125] Optionally, in the above step 507, the electronic device uses the LS algorithm to determine the predistortion coefficient of the second predistortion model. During the determination process, the electronic device determines the first matrix transpose of the feedback signal and the second matrix transpose of the fractionally aligned distortion signal, as shown in the following formula (9):

[0126]

[0127] Among them, f on the left side of the equal sign represents the first matrix transpose of the feedback signal, z″ on the left side of the equal sign represents the second matrix transpose of the fractionally aligned distortion signal, the superscript “T” represents the matrix transpose, and N represents the number of points of the test signal. The second pre-distortion model takes the polynomial model as an example (the memory polynomial model can be expanded by memory terms on this basis), the input signal matrix of the second pre-distortion model is shown in the following formula (10), and the pre-distortion coefficient of the second pre-distortion model is shown in the following formula (11):

[0128] F=[f,f|f|,f|f| 2 ,…,f|f| K-1 ] T Formula (10)

[0129] A=[a0,a1,a2,…,a K-1 ] T Formula (11)

[0130] After the electronic device determines the first transposed matrix and the second transposed matrix, it determines an expression of the second pre-distortion model according to the first matrix transposed matrix and the second matrix transposed matrix. The expression is shown in the following formula (12):

[0131] z″=FA formula (12)

[0132] Afterwards, the electronic device processes the expression using a least square method to determine the predistortion coefficient of the second predistortion model, and determines the second predistortion model according to the expression of the second predistortion model and the predistortion coefficient of the second predistortion model.

[0133] Optionally, when the electronic device processes the expression using the least squares method, the number of sampling points N of the signal and the number of parameters K of the second predistortion model generally satisfy N>>K. Therefore, there is a unique least squares solution to formula (12). According to the LS algorithm, the least squares solution is shown in the following formula (13):

[0134] A=(F H F) -1 F Hz″ Formula (13)

[0135] in," H " represents the conjugate transpose operation," -1 " represents the traditional matrix inversion operation, (F H F) -1 F H It is also called the generalized inverse matrix of the matrix F, that is, the left inverse matrix, and A is the predistortion coefficient of the second predistortion model obtained by the LS algorithm.

[0136] With this solution, the least squares algorithm is used to calculate and update the coefficients of the predistortion model, avoiding the risk of non-convergence of the traditional iterative algorithm.

[0137] Optionally, in the above embodiment, when the electronic device uses the least squares method to process the expression to determine the predistortion coefficient of the second predistortion model, the least squares method is used to process the expression by orthogonal triangular decomposition and / or Given rotation to determine the predistortion coefficient of the second predistortion model.

[0138] Exemplarily, in the above step 507, the electronic device uses the orthogonal triangular QR calculation in the matrix inversion process of the LS algorithm. In the QR-based calculation process, any matrix can be expressed as the product of an orthogonal matrix and an upper triangular matrix, as described in the following formula (14):

[0139] B=Q×R Formula (14)

[0140] Wherein, B represents any matrix, Q represents an orthogonal matrix, the inverse matrix of an orthogonal matrix is ​​its own conjugate transpose, and R represents an upper triangular matrix. According to formula (14), the inverse operation of any matrix B can be obtained as follows (15):

[0141] B=(Q*R) -1 =R -1 *Q -1 =R -1 *Q H Formula (15)

[0142] QR decomposition uses the Given rotation method. When implementing Given rotation in FPGA, it is completed through the Cordic rotation algorithm. Taking a 3×3 matrix as an example, the QR decomposition using Givens expression is shown in the following formula (16):

[0143]

[0144] in, The MATLAB algorithm for the elements that change due to Givens rotation is as follows:

[0145]

[0146] In the embodiment of the present application, the QR decomposition adopts the Givens rotation method, which can also be referred to as the Given QR decomposition algorithm, and can complete the inversion operation of a large matrix. Since the Given QR decomposition algorithm uses a loop iteration method to solve the matrix, the FPGA can further optimize the Givens QR decomposition operation process through a pipeline method. While ensuring that the FPGA resource occupancy is acceptable, the efficiency of the matrix inversion operation is improved.

[0147] Optionally, in the above embodiment, the evaluation formula of the correlation coefficient in step 507 is as shown in formula (17):

[0148]

[0149] Among them, S represents the correlation coefficient, w n represents the weight factor of the nth item, s n It represents the scoring result of the nth item, N represents the total number of nonlinear evaluation items. The distribution of weights needs to be evaluated based on the characteristics of the specific power amplifier and cannot be generalized.

[0150] Preferably, the optional nonlinear evaluation items are: 1dB compression point, third-order AC coefficient, adjacent channel power ratio, error vector magnitude and normalized mean square error. Finally, when S>P, the LS estimation module is enabled to calculate the second predistortion coefficient. P represents a preset threshold.

[0151] Optionally, in the above embodiment, the purpose of the electronic device performing the delay alignment in step 506 is to estimate an accurate second predistortion coefficient. During the delay alignment process, it is necessary to perform delay estimation on the first predistortion signal z(n) and the feedback signal f(n), and the integer alignment method is a correlation operation, as shown in the following formula (18):

[0152]

[0153] Where N represents the number of sample points sampled during delay estimation, n represents the sampling sequence number, p represents the delay time sequence, and the p corresponding to the maximum modulus value of R(p) is the loop delay time, that is, the integer delay amount. The calculation method of the integer delay amount is shown in formula (19):

[0154]

[0155] The specific method of fractional alignment is to align the phase of the signal in the frequency domain after Fourier transform, as shown in the above formula (6).

[0156]

[0157] In formula (6), the range of q is as shown in formula (7):

[0158]

[0159] Where Q represents the fractional delay, F * (e jw ) represents the frequency domain expression of the conjugate of the feedback signal f(n) after Fourier transform, Z′(e jw ) represents the expression of z′ in the frequency domain after Fourier transform, and Fac represents the fractional delay accuracy, which represents the total number of fractional delay shifts within one time unit.

[0160] After the electronic device calculates the loop delay value with a fractional order, that is, the fractional delay amount, N aligned sequences z" (n), f (n) are obtained, and the signal is normalized. The normalized z" (n) is shown in the following formula (20), and the normalized f (n) is shown in the following formula (21):

[0161] z″(n)=z″(n) / max(|z″(n)|Formula (20)

[0162] f(n)=f(n) / max(|f(n)|) Formula (21)

[0163] In formula (20), z" (n) on the left side of the equal sign represents the normalized z" (n), and in formula (21), f (n) on the left side of the equal sign represents the normalized f (n).

[0164] In step 507, the predistortion coefficients are solved for the normalized signal according to the LS algorithm, as shown in the following formula (13):

[0165] A=(F H F) -1 F H z″ Formula (13)

[0166] The meaning of each parameter in formula (13) can be found in the above description and will not be repeated here.

[0167] In formula (13), A is the predistortion coefficient vector, F is the predistortion model input matrix, and z'' is the predistortion model output vector. Taking the predistortion model selection polynomial as an example, the expressions of a, F, and z'' are shown in the following formulas (22), (10), and (23):

[0168] a=[a0,a1,a2,a3,…,a K-1 ]Formula (22)

[0169] F=[f,f|f|,f|f| 2 ,…,f|f| K-1 ] T Formula (10)

[0170] z″=[z″(1),z″(2),…z″(N)] T Formula (23)

[0171] Wherein, K represents the nonlinear order of the second predistortion model. The selection of K value is related to the nonlinear characteristics of the power amplifier. It is usually 5 or 7. The specific selection is related to the actual characteristics of the power amplifier. T ” represents the transpose operation of the matrix, f=[f(1),f(2),f(3),…,f(N)]; N is the number of sample points for calculating the predistortion coefficients, which is the same as the number of signal sampling points.

[0172] In the process of solving the predistortion coefficient, it is necessary to solve F H The inverse matrix of F, since F H F is a large matrix of order N*N. If the inverse matrix is ​​solved by a direct inversion algorithm, the amount of calculation is very large. At the same time, in the data fixed-point calculation process, it is also very likely to introduce errors caused by data accuracy. Therefore, the conventional LS algorithm is not suitable for the case of online updating of pre-distortion coefficients in this application. Among them, the conventional LS algorithm is, for example, a calculation method for offline pre-distortion coefficients.

[0173] In order to solve the difficulty of inverting large matrices, the embodiment of the present application introduces a QR decomposition algorithm for matrix inversion, which can simplify the calculation process and amount of matrix inversion operations while ensuring calculation accuracy, and use QR decomposition for simplification.

[0174] First, define B as the large matrix to be inverted, as shown in the following formula (24):

[0175] B=F H *F formula (24)

[0176] From the knowledge of matrix theory, we know that any matrix can be expressed as the product of a positive matrix and an upper triangular matrix, as shown in formula (14):

[0177] B=Q×R formula (14).

[0178] Wherein, B represents any matrix, Q represents an orthogonal matrix, the inverse matrix of an orthogonal matrix is ​​its own conjugate transpose, and R represents an upper triangular matrix. According to formula (14), the inverse operation of any matrix B can be obtained as follows (15):

[0179] B=(Q*R) -1 =R-1 *Q -1 =R -1 *Q H Formula (15)

[0180] QR decomposition uses Given rotation. When Given rotation is implemented in FPGA, it is completed through Cordic rotation algorithm.

[0181] After obtaining the inverse matrix of B according to the above matrix inversion algorithm, the predistortion coefficient A can be obtained by substituting it into formula (13).

[0182] A=(F H F) -1 F H z″ Formula (13)

[0183] The predistortion coefficient A of the second predistortion model is obtained by solving according to the above steps. Then, the first predistortion model is updated according to the second predistortion coefficient to obtain the second predistortion model.

[0184] Assuming that the second baseband signal is represented by x(n), the second predistortion model is used to perform predistortion processing on the second baseband signal x(n) to obtain a second predistortion signal z(n), as shown in the following formula (25):

[0185]

[0186] The above is a process of updating the predistortion coefficients. By repeating the above process in sequence, the next update of the predistortion coefficients can be completed based on the current predistortion state.

[0187] The above-mentioned closed-loop predistortion method is suitable for scenarios where the transmitter usage scenarios are complex and changeable and have a signal feedback loop.

[0188] Figure 8 This is a block diagram of the internal structure of the FPGA in the closed-loop shortwave communication method provided in the embodiment of the present application. Figure 8 In the block diagram of the closed-loop predistortion structure inside the FPGA, the input signal represents the digital baseband signal before up-conversion, that is, the first baseband signal mentioned above. The feedback signal represents the signal of the first baseband signal after passing through the predistortion module, up-conversion module, digital-to-analog conversion module, power amplifier, harmonic filter, directional coupler, analog-to-digital conversion module, and down-conversion module.

[0189] The control interface is used to complete the setting of the working state of the entire pre-distortion module, including the comparison of the correlation coefficient of the current feedback signal and the preset threshold and the switching of the enabling state. The pre-distortion state interface is used to identify the working state of the pre-distortion.

[0190] The output signal represents the baseband signal after pre-distortion processing, and the subsequent stage will be sent to the digital up-conversion module to complete the optimization process of the pre-distortion technology.

[0191] Fig. 9 This is a diagram showing the effect of the closed-loop shortwave communication method provided by the embodiment of the present application. Fig. 9 The dotted line indicates that the signal has not been pre-distorted, and the solid line indicates that the signal has been pre-distorted. It can be seen that after the pre-distortion processing technology is used, the transmitter's third-order intermodulation index (2MHz~30MHz) is improved from the original -20dB to more than -40dB, and the transmitter's spectrum quality is also greatly improved.

[0192] The following is an embodiment of the device of the present application, which can be used to execute the embodiment of the method of the present application. For details not disclosed in the embodiment of the device of the present application, please refer to the embodiment of the method of the present application.

[0193] Fig.10 A schematic diagram of the structure of a shortwave communication device based on a closed loop provided in an embodiment of the present application. The shortwave communication device based on a closed loop 1000 comprises: a predistortion module 1001 , an update module 1002 , and a communication module 1003 .

[0194] The predistortion module 1001 is used to perform predistortion processing on the first baseband signal by using a first predistortion model to obtain a first distorted signal;

[0195] An updating module 1002, configured to update the first pre-distortion model according to the first distorted signal to obtain a second pre-distortion model;

[0196] The predistortion module 1001 is further configured to perform predistortion processing on the second baseband signal using the second predistortion model to obtain a second distorted signal, wherein the first baseband signal and the second baseband signal are signals transmitted twice successively by the transmitter of the electronic device;

[0197] The communication module 1003 is configured to perform shortwave communication according to the second distorted signal.

[0198] In a feasible implementation, the updating module 1002 is used to determine a feedback signal according to the first distortion signal; determine a correlation coefficient according to the first baseband signal and the feedback signal; when the correlation coefficient is greater than a preset threshold, update the first pre-distortion model according to the first distortion signal to obtain a second pre-distortion model.

[0199] In a feasible implementation, when the update module 1002 determines the feedback signal based on the first distorted signal, it is used to up-convert the first distorted signal to the RF domain to obtain a RF signal; perform digital-to-analog conversion on the RF signal to obtain an analog signal; amplify the power of the analog signal to obtain an amplified signal; perform harmonic filtering on the amplified signal to obtain a filtered signal; and determine the feedback signal based on the filtered signal.

[0200] In a feasible implementation, when the correlation coefficient is greater than a preset threshold, the updating module 1002 updates the first pre-distortion model according to the first distortion signal to obtain the second pre-distortion model, and is used to use the feedback signal as a reference signal to perform integer delay alignment on the first distortion signal to obtain an integer-aligned distortion signal; use the feedback signal as a reference signal to perform fractional delay alignment on the integer-aligned distortion signal to obtain a fractionally-aligned distortion signal; determine a pre-distortion coefficient according to the fractionally-aligned distortion signal and the feedback signal; and update the first pre-distortion model according to the pre-distortion coefficient to obtain the second pre-distortion model.

[0201] In a feasible implementation, when the updating module 1002 determines the predistortion coefficient according to the fractionally aligned distortion signal and the feedback signal, it is used to determine the first matrix transpose of the feedback signal and the second matrix transpose of the fractionally aligned distortion signal; determine the expression of the second predistortion model according to the first matrix transpose and the second matrix transpose; and process the expression using the least squares method to determine the predistortion coefficient of the second predistortion model.

[0202] In a feasible implementation, when the updating module 1002 processes the expression using the least squares method to determine the predistortion coefficient of the second predistortion model, it is configured to process the expression using the orthogonal triangular decomposition and / or Given rotation when using the least squares method to determine the predistortion coefficient of the second predistortion model.

[0203] In a feasible implementation manner, when the correlation coefficient is less than or equal to a preset threshold, the predistortion coefficient of the second predistortion model is equal to the predistortion coefficient of the first predistortion model.

[0204] The closed-loop shortwave communication device provided in the embodiment of the present application can execute the actions of the electronic device in the above embodiment. Its implementation principle and technical effects are similar and will not be repeated here.

[0205] Fig.11 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Fig.11 As shown, the electronic device 1100 includes:

[0206] Processor 1101 and memory 1102;

[0207] The memory 1102 stores computer instructions;

[0208] The processor 1101 executes the computer instructions stored in the memory 1102, so that the processor 1101 executes the closed-loop-based shortwave communication method as described above.

[0209] The specific implementation process of the processor 1101 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0210] Optionally, the electronic device 11000 further includes a communication component 1103 . The processor 1101 , the memory 1102 and the communication component 1103 may be connected via a bus 1104 .

[0211] The embodiment of the present application also provides a computer-readable storage medium, in which computer instructions are stored. When the computer instructions are executed by a processor, they are used to implement the above shortwave communication method based on a closed loop.

[0212] The embodiment of the present application also provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the shortwave communication method based on a closed loop as described above is implemented.

[0213] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0214] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A shortwave communication method based on a closed loop, characterized in that: Applied to electronic equipment, the method comprises: Performing predistortion processing on the first baseband signal using a first predistortion model to obtain a first distorted signal; Up-converting the first distorted signal to a radio frequency domain to obtain a radio frequency signal; Performing digital-to-analog conversion on the radio frequency signal to obtain an analog signal; amplifying the power of the analog signal to obtain an amplified signal; Performing harmonic filtering on the amplified signal to obtain a filtered signal; Performing analog-to-digital conversion on the filtered signal, and down-converting the filtered signal after the analog-to-digital conversion to obtain a baseband signal, and using the baseband signal obtained by the down-conversion as a feedback signal; aligning the feedback signal and the first distorted signal; Determine a correlation coefficient according to the first baseband signal and the feedback signal; the correlation coefficient is obtained by integrating the scores and weights corresponding to the nonlinear parameters required by the power amplifier; When the correlation coefficient is greater than a preset threshold, performing least squares estimation on the aligned first distorted signal and the feedback signal to obtain a predistortion coefficient of a second predistortion model; updating the first predistortion model according to the predistortion coefficient to obtain the second predistortion model; Using the second predistortion model to perform predistortion processing on the second baseband signal to obtain a second distorted signal, wherein the first baseband signal and the second baseband signal are signals transmitted twice by the transmitter of the electronic device; Shortwave communication is performed according to the second distorted signal.

2. The method according to claim 1, characterized in that The aligning the feedback signal and the first distortion signal comprises: Using the feedback signal as a reference signal, performing integer delay alignment on the first distorted signal to obtain an integer-aligned distorted signal; Using the feedback signal as a reference signal, performing fractional delay alignment on the integer-aligned distorted signal to obtain a fractionally-aligned distorted signal; When the correlation coefficient is greater than a preset threshold, performing least squares estimation on the aligned first distortion signal and the feedback signal to obtain a predistortion coefficient of a second predistortion model includes: When the correlation coefficient is greater than a preset threshold, a least squares method is performed on the fractionally aligned distortion signal and the feedback signal to determine a predistortion coefficient.

3. The method according to claim 2, characterized in that The performing least squares estimation on the fractionally aligned distortion signal and the feedback signal comprises: determining a first matrix transpose of the feedback signal and a second matrix transpose of the fractionally aligned distortion signal; Determining an expression of the second predistortion model according to the first matrix transpose and the second matrix transpose; The expression is processed using a least square method to determine predistortion coefficients of the second predistortion model.

4. The method according to claim 3, characterized in that The using least square method to process the expression to determine the predistortion coefficient of the second predistortion model includes: When using the least square method, the expression is processed by adopting orthogonal triangular decomposition and / or Given rotation to determine the predistortion coefficients of the second predistortion model.

5. The method according to any one of claims 1 to 4, characterized in that: When the correlation coefficient is less than or equal to a preset threshold, the predistortion coefficient of the second predistortion model is equal to the predistortion coefficient of the first predistortion model.

6. A shortwave communication device based on a closed loop, characterized in that: Applied to electronic equipment, the device comprises: A predistortion module, configured to perform predistortion processing on the first baseband signal using a first predistortion model to obtain a first distorted signal; An updating module, configured to up-convert the first distorted signal to a radio frequency domain to obtain a radio frequency signal; perform digital-to-analog conversion on the radio frequency signal to obtain an analog signal; amplify the power of the analog signal to obtain an amplified signal; perform harmonic filtering on the amplified signal to obtain a filtered signal; perform analog-to-digital conversion on the filtered signal, and down-convert the filtered signal after analog-to-digital conversion to obtain a baseband signal, and use the baseband signal obtained by down-conversion as a feedback signal; align the feedback signal and the first distorted signal; determine a correlation coefficient based on the first baseband signal and the feedback signal; the correlation coefficient is obtained by integrating the scores and weights corresponding to the nonlinear parameters required by the power amplifier; when the correlation coefficient is greater than a preset threshold, perform least squares estimation on the aligned first distorted signal and the feedback signal to obtain a predistortion coefficient of a second predistortion model; update the first predistortion model based on the predistortion coefficient to obtain the second predistortion model; The predistortion module is further used to perform predistortion processing on the second baseband signal using the second predistortion model to obtain a second distorted signal, wherein the first baseband signal and the second baseband signal are signals transmitted twice by the transmitter of the electronic device; A communication module is used to perform shortwave communication according to the second distorted signal.

7. An electronic device comprising a processor, a memory, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the electronic device implements the method according to any one of claims 1 to 5.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, which are used to implement the method according to any one of claims 1 to 5 when executed by a processor.

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