Evm correction transmitter system and method based on real-time feedback and predistortion

Abstract

This application belongs to the field of wireless communication technology, specifically disclosing a transmitter system and method based on real-time feedback and pre-distortion EVM correction. The system includes: a digital pre-corrector, an RF transmit link, a feedback receive link, and a control module connected in sequence; the digital pre-corrector receives correction parameter information from the control module and performs pre-correction processing on the baseband signal according to the correction parameter information; the RF transmit link generates a target RF signal based on the pre-corrected baseband signal and transmits it; the feedback receive link receives the target RF signal and processes it into a feedback digital signal; the control module determines the EVM value of the target RF signal based on the baseband signal and the feedback digital signal, and updates the correction parameter information with the goal of minimizing the EVM value, thereby adjusting the quality of the target RF signal transmitted by the RF transmit link. This application can effectively improve the performance stability and modulation quality of the transmitter in complex operating environments.

Description

Technical Field

[0001] This application belongs to the field of wireless communication technology, specifically to the field of radio frequency processor technology, and more specifically, to an EVM correction transmitter system and method based on real-time feedback and predistortion. Background Technology

[0002] Error Vector Magnitude (EVM) is a key metric for measuring the modulation quality of a digital transmitter. In practical RF transmission links, the nonlinear characteristics of the power amplifier (PA) and defects in the I / Q modulator are two major factors contributing to EVM degradation. Therefore, EVM correction is particularly important to ensure the stable operation of the digital transmitter.

[0003] Traditional EVM calibration methods typically involve a one-time static calibration performed at the transmitter's factory or during initial power-on. However, in actual operation, the nonlinear characteristics of the power amplifier (PA) drift with changes in ambient temperature, operating frequency, and output power level. The aforementioned static calibration method cannot adapt to these dynamic changes, resulting in poor calibration performance and ultimately a decrease in transmitter performance stability.

[0004] Therefore, how to better realize EVM-based transmitters has become a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this application is to better realize a transmitter based on EVM correction, and to solve the problem that the EVM correction method of traditional transmitters has poor correction effect, which leads to a decrease in transmitter performance stability.

[0006] To achieve the above objectives, in a first aspect, this application provides an EVM-corrected transmitter system based on real-time feedback and predistortion, comprising: The digital pre-calibrator, the radio frequency transmission link, the feedback reception link, and the control module are connected in sequence; the digital pre-calibrator is also connected to the control module. The digital pre-calibrator is used to receive calibration parameter information sent by the control module and perform pre-calibration processing on the baseband signal according to the calibration parameter information; The radio frequency transmission link is used to generate a target radio frequency signal based on the pre-corrected baseband signal for transmission. The feedback receiving link is used to receive the target radio frequency signal and process the target radio frequency signal into a feedback digital signal; The control module is used to determine the EVM value of the target radio frequency signal based on the baseband signal and the feedback digital signal, and to update the correction parameter information with the goal of minimizing the EVM value, so as to adjust the quality of the target radio frequency signal transmitted by the radio frequency transmission link.

[0007] Optionally, the digital pre-calibrator includes a pre-calibrator and a digital-to-analog converter connected in sequence; The first input terminal of the pre-calibrator serves as the first input terminal of the digital pre-calibrator for receiving the baseband signal; the second input terminal of the pre-calibrator serves as the second input terminal of the digital pre-calibrator for receiving the calibration parameter information; and the output terminal of the digital-to-analog converter serves as the output terminal of the digital pre-calibrator. The pre-corrector is used to perform joint pre-correction processing on the baseband signal for I / Q defects and PA nonlinearity based on the correction parameter information, and outputs a joint pre-correction signal; The digital-to-analog converter is used to perform digital-to-analog conversion processing on the joint pre-correction signal and output the pre-corrected baseband signal.

[0008] Optionally, the pre-corrector includes an I / Q defect compensation module and a PA nonlinearity pre-distortion module cascaded in sequence. The I / Q defect compensation module is used to correct the I / Q amplitude distortion, I / Q phase error and I / Q DC offset of the I / Q modulator in the RF transmission link. The PA nonlinearity pre-distortion module is used to correct the PA nonlinearity distortion of the power amplifier in the RF transmission link. The correction parameter information includes parameters for compensating for I / Q amplitude distortion, I / Q phase error, and I / Q DC offset, as well as pre-distortion coefficients for PA nonlinear distortion compensation.

[0009] Optionally, the control module includes a synchronization and alignment module, an EVM calculation module, and a correction parameter update module connected in sequence; The input terminal of the synchronization and alignment module serves as the input terminal of the control module, and the output terminal of the correction parameter update module serves as the output terminal of the control module, which is connected to the second input terminal of the pre-corrector. The synchronization and alignment module is used to perform time synchronization and phase rotation alignment processing on the baseband signal and the feedback digital signal; The EVM calculation module is used to calculate the EVM value of the target radio frequency signal based on the aligned baseband signal and the feedback digital signal; The correction parameter update module is used to perform minimum mean square error analysis using the EVM value with the goal of minimizing the EVM value, update the correction parameter information according to the analysis results, and send the updated correction parameter information to the pre-corrector.

[0010] Optionally, the radio frequency transmission link includes an I / Q modulator, a power amplifier, a coupler, and a transmitting antenna connected in sequence; The input terminal of the I / Q modulator is connected to the digital-to-analog converter as the input terminal of the radio frequency transmission link, and is used to perform up-conversion processing on the pre-corrected baseband signal to output the original radio frequency signal. The power amplifier is used to amplify the power of the original radio frequency signal and output the target radio frequency signal; The second output terminal of the coupler is connected to the first output terminal of the radio frequency transmission link and the input terminal of the feedback receiving link, for acquiring the target radio frequency signal and sending the target radio frequency signal to the feedback receiving link; The transmitting antenna serves as the second output terminal of the radio frequency transmission link and is used to transmit the target radio frequency signal.

[0011] Optionally, the feedback receiving link includes an analog-to-digital converter and a demodulator connected in sequence; the input terminal of the analog-to-digital converter serves as the input terminal of the feedback receiving link, and the output terminal of the demodulator serves as the output terminal of the feedback receiving link. The analog-to-digital converter is used to receive the target radio frequency signal and process the target radio frequency signal into a corresponding digital signal; The demodulator is used to perform down-conversion processing on the digital signal and output the feedback digital signal.

[0012] Secondly, this application provides a control method for an EVM-corrected transmitter system based on real-time feedback and predistortion as described in any of the foregoing embodiments, comprising: Receive correction parameter information, perform pre-correction processing on the baseband signal according to the correction parameter information, and output the pre-corrected baseband signal; The target radio frequency signal is generated and transmitted based on the pre-corrected baseband signal, and the target radio frequency signal is collected and processed into a feedback digital signal. The EVM value of the target RF signal is determined based on the baseband signal and the feedback digital signal, and the correction parameter information is updated with the goal of minimizing the EVM value to adjust the quality of the target RF signal.

[0013] Optionally, the step of performing pre-correction processing on the baseband signal based on the correction parameter information and outputting the pre-corrected baseband signal includes: Based on the correction parameter information, the baseband signal is subjected to joint pre-correction processing for I / Q defects and PA nonlinearity, and a joint pre-correction signal is output. The joint pre-corrected signal is subjected to digital-to-analog conversion processing to output the pre-corrected baseband signal.

[0014] Optionally, determining the EVM value of the target RF signal based on the baseband signal and the feedback digital signal, and updating the correction parameter information with the goal of minimizing the EVM value to adjust the quality of the target RF signal, includes: The baseband signal and the feedback digital signal are subjected to time synchronization and phase rotation alignment processing; The EVM value of the target radio frequency signal is calculated based on the aligned baseband signal and the feedback digital signal; With the goal of minimizing the EVM value, minimum mean square error analysis is performed using the EVM value, and the correction parameter information is updated based on the analysis results to adjust the quality of the target radio frequency signal.

[0015] Optionally, the step of generating a target radio frequency signal based on the pre-corrected baseband signal and transmitting it includes: The pre-corrected baseband signal is up-converted to output the original radio frequency signal; The original radio frequency signal is amplified to output the target radio frequency signal; The target radio frequency signal is transmitted through the transmitting antenna.

[0016] Overall, the technical solutions conceived in this application have the following beneficial effects compared with the prior art: This application provides a transmitter system and method based on real-time feedback and predistortion EVM correction. By introducing a digital precorrector, a feedback receiving link, and a control module, the feedback receiving link couples the RF signal from the transmitter to a feedback digital signal. The control module then synchronizes and aligns the feedback digital signal with the original baseband reference signal, and calculates the error vector amplitude (EVM) value in real time. Minimizing this EVM value is the direct objective for dynamically updating the correction parameters of the digital precorrector, which simultaneously compensates for I / Q modulator defects and power amplifier nonlinearity, thus forming a closed-loop control system. This system can dynamically track changes in RF link characteristics, achieving online real-time optimization and correction of EVM. It can effectively improve the performance stability and modulation quality of the transmitter in complex operating environments, solve the shortcomings of traditional static calibration methods, and reduce dependence on external testing equipment, thereby lowering the cost of the transmitter system. Attached Figure Description

[0017] Figure 1 This is one of the structural schematic diagrams of the EVM correction transmitter system based on real-time feedback and predistortion provided in the embodiments of this application; Figure 2 This is the second schematic diagram of the EVM correction transmitter system based on real-time feedback and predistortion provided in the embodiments of this application; Figure 3 This is a schematic diagram of the EVM correction process performed by the EVM correction transmitter system provided in this application embodiment; Figure 4 This is a flowchart illustrating the control method of the EVM correction transmitter system provided in the embodiments of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0019] The terms "first" and "second," etc., used in the specification and claims of this application are used to distinguish different objects, not to describe a specific order of objects. For example, "first input terminal" and "second input terminal," etc., are used to distinguish different input terminals, not to describe a specific order of input terminals.

[0020] In this application, the term "electrical connection" can refer to a direct circuit connection or a signal transmission via a communication protocol.

[0021] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0022] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more, for example, multiple processing units means two or more processing units, multiple elements means two or more elements, etc.

[0023] Currently, existing technologies also offer high-precision EVM measurement methods; however, these methods typically rely on external testing equipment, such as expensive vector signal analyzers (VSAs), which increases the cost and complexity of the transmitter system and makes online real-time monitoring and correction inconvenient. To address the shortcomings of the existing technologies, this application provides an EVM correction transmitter system based on real-time feedback and predistortion.

[0024] The embodiments of this application are described below with reference to the accompanying drawings.

[0025] Figure 1This is one of the structural schematic diagrams of the EVM correction transmitter system based on real-time feedback and predistortion provided in the embodiments of this application, such as... Figure 1 As shown, it includes: The digital pre-calibrator 1, the radio frequency transmission link 2, the feedback reception link 3, and the control module 4 are connected in sequence; the digital pre-calibrator 1 is also connected to the control module 4. The digital pre-calibrator 1 is used to receive calibration parameter information from the control module 4 and perform pre-calibration processing on the baseband signal according to the calibration parameter information; RF transmission link 2 is used to generate a target RF signal based on the pre-calibrated baseband signal for transmission; Feedback receiving link 3 is used to acquire the target radio frequency signal and process the target radio frequency signal into a feedback digital signal; The control module 4 is used to determine the EVM value of the target radio frequency signal based on the baseband signal and the feedback digital signal, and to update the correction parameter information with the goal of minimizing the EVM value, so as to adjust the quality of the target radio frequency signal transmitted by the radio frequency transmission link 2.

[0026] Specifically, the correction parameter information described in the embodiments of this application is used to adjust the relevant parameters of the digital pre-corrector so that the digital pre-corrector can perform joint pre-correction for I / Q defects and PA nonlinearity in the RF transmit link.

[0027] The target radio frequency signal described in this application refers to a radio frequency signal with sufficient power level obtained by signal modulation of a digital baseband signal, suitable for wireless transmission by a transmitter. It should be noted that the baseband signal in this application is a digital baseband signal (I / Q signal).

[0028] In the embodiments of this application, the transmitter system may consist of a digital precalibrator, an RF transmission link, a feedback reception link, and a control module. The digital precalibrator, RF transmission link, feedback reception link, control module, and digital precalibrator are connected in sequence to form a closed-loop control system.

[0029] In the embodiments of this application, the digital precalibrator receives the baseband signal and simultaneously receives the calibration parameter information sent by the current control module. It then adjusts its own module parameters according to the current calibration parameter information to achieve the current precalibration processing of the baseband signal and obtain the precalibrated baseband signal.

[0030] Furthermore, the RF transmission link can receive the pre-corrected baseband signal transmitted from the digital pre-corrector. On the one hand, the pre-corrected baseband signal carries joint pre-correction information for I / Q defects and PA nonlinearity, which can simultaneously compensate for I / Q modulator defects and PA nonlinearity in the RF transmission link. On the other hand, after modulating the pre-corrected baseband signal, the target RF signal is generated and transmitted.

[0031] Meanwhile, the feedback receiving link can acquire the target radio frequency signal by coupling the radio frequency output of the transmitter and process the target radio frequency signal into a feedback digital signal.

[0032] Furthermore, in the embodiments of this application, the introduced control module can accept the baseband signal and use it as a reference signal to perform EVM analysis with the received feedback digital signal to calculate the EVM value of the target RF signal. Here, the EVM value is a precise measure of the quality of the final output RF signal of the system.

[0033] Simultaneously, the system can update the correction parameters based on a pre-set adaptive algorithm, aiming to minimize the EVM value. If the current EVM value has not converged to the optimal value, the digital pre-corrector, upon receiving the updated correction parameters, continues to pre-correct the baseband signal for the next time step. This process is repeated, iteratively processing the EVM value until it converges to the optimal value. Thus, by continuously comparing the transmitted RF signal with the feedback digital signal and using this error to drive the update of the correction parameters, the system can adaptively track changes in the RF link characteristics. Through continuous adjustment of the input signal, it ensures that the system output always maintains the EVM at the optimal level, thereby achieving real-time dynamic optimization of the RF signal quality transmitted by the RF transmission link.

[0034] The EVM-based transmitter system based on real-time feedback and predistortion in this application introduces a digital pre-corrector, a feedback receiving link, and a control module. The feedback receiving link couples the RF signal from the transmitter to a feedback digital signal. The control module then synchronizes and aligns the feedback digital signal with the original baseband reference signal, calculating the error vector amplitude (EVM) value in real time. Minimizing this EVM value is the direct objective for dynamically updating the correction parameters of the digital pre-corrector, simultaneously compensating for I / Q modulator defects and power amplifier nonlinearities. This forms a closed-loop control system that dynamically tracks changes in RF link characteristics, achieving online real-time optimization and correction of the EVM. This effectively improves the transmitter's performance stability and modulation quality in complex operating environments, overcomes the shortcomings of traditional static calibration methods, reduces reliance on external testing equipment, and lowers the transmitter system cost.

[0035] Figure 2 This is the second schematic diagram of the EVM correction transmitter system based on real-time feedback and predistortion provided in the embodiments of this application, as shown below. Figure 2 As shown, in an embodiment of this application, the digital pre-calibrator 1 may include a pre-calibrator 11 and a digital-to-analog converter 12 connected in sequence; The first input terminal of the pre-calibrator 11 serves as the first input terminal of the digital pre-calibrator 1 for receiving baseband signals, and the second input terminal of the pre-calibrator 11 serves as the second input terminal of the digital pre-calibrator 1 for receiving calibration parameter information; the output terminal of the digital-to-analog converter 12 serves as the output terminal of the digital pre-calibrator 1. The pre-corrector 11 is used to perform joint pre-correction processing on the baseband signal for I / Q defects and PA nonlinearity based on the correction parameter information, and outputs a joint pre-correction signal; The digital-to-analog converter 12 is used to perform digital-to-analog conversion processing on the joint pre-correction signal and output the pre-corrected baseband signal.

[0036] Specifically, in the embodiments of this application, the digital pre-calibrator can be composed of a pre-calibrator and a digital-to-analog converter connected in sequence. The pre-calibrator can perform joint pre-calibration processing on the input baseband signal for I / Q defects and PA nonlinearity based on the current calibration parameter information, thereby outputting a joint pre-calibrated signal.

[0037] Here, it can be understood that the correction parameter information is a set of adjustable joint parameters used to control the pre-corrector to perform joint pre-correction of I / Q defects and PA nonlinearity.

[0038] Based on the above embodiments, as an optional embodiment, the pre-corrector includes an I / Q defect compensation module and a PA nonlinearity pre-distortion module cascaded in sequence. The I / Q defect compensation module is used to correct the I / Q amplitude distortion, I / Q phase error and I / Q DC offset of the I / Q modulator in the RF transmission link, and the PA nonlinearity pre-distortion module is used to correct the PA nonlinearity distortion of the power amplifier in the RF transmission link. The correction parameter information includes parameters used to compensate for I / Q amplitude distortion, I / Q phase error, and I / Q DC offset, as well as pre-distortion coefficients used for PA nonlinear distortion compensation.

[0039] Specifically, in the embodiments of this application, the pre-corrector includes an I / Q defect compensation module and a PA nonlinear predistortion module cascaded in sequence. After the digital baseband signal is input to the pre-corrector, the parameters in the I / Q defect compensation module for compensating I / Q amplitude distortion, I / Q phase error, and I / Q DC offset are adjusted according to the current correction parameter information. The predistortion coefficients in the PA nonlinear predistortion module for PA nonlinear distortion compensation are also adjusted. This allows the I / Q defect compensation module to perform pre-correction on the digital baseband signal for I / Q defect compensation. The output pre-corrected signal then undergoes pre-correction processing by the PA nonlinear predistortion module, ultimately outputting a joint pre-corrected signal.

[0040] Existing technologies typically treat I / Q modulator defects and PA nonlinearity as two independent problems, completely ignoring the bidirectional coupling effect between them. That is, I / Q correction changes the signal statistical characteristics of the input PA, thus affecting the PA's nonlinear behavior, while PA nonlinear correction, such as the nonlinear transformation of digital predistortion (DPD), in turn introduces new I / Q distortion, and the two intertwine to generate new coupled distortion components. In the embodiments of this application, the RF transmit link is modeled end-to-end as a unified composite nonlinear system, with the final output EVM as the sole objective. Global optimization is achieved through joint pre-correction parameters (i.e., correction parameter information), thereby transforming the traditional "step-by-step optimization with local optima" approach into a "joint optimization with global optima" approach.

[0041] The transmitter system of this application embodiment constructs a pre-corrector by introducing a cascaded I / Q defect compensation module and a PA nonlinearity pre-distortion module, which can effectively achieve joint pre-correction for I / Q defects and PA nonlinearity. By utilizing the coupling effect between I / Q defect correction and PA nonlinearity correction, the globally optimal correction effect can be achieved.

[0042] Furthermore, in the embodiments of this application, the joint pre-calibrated signal finally output by the pre-calibrator is processed by a digital-to-analog converter and converted into a corresponding analog signal, thus obtaining the pre-calibrated baseband signal. In this way, when the pre-calibrated baseband signal is subsequently processed by the I / Q modulator and power amplifier in the RF transmission link, it can effectively compensate for I / Q modulator defects and PA nonlinearity, ensuring the quality of the RF transmission signal transmitted by the RF transmission link.

[0043] Continue to refer to Figure 2 Based on the above embodiments, as an optional embodiment, the control module 4 includes a synchronization and alignment module 41, an EVM calculation module 42, and a correction parameter update module 43 connected in sequence. The input terminal of the synchronization and alignment module 41 serves as the input terminal of the control module 4, and the output terminal of the correction parameter update module 43 serves as the output terminal of the control module 4, which is connected to the second input terminal of the pre-corrector 11. Synchronization and alignment module 41 is used to perform time synchronization and phase rotation alignment processing on baseband signal and feedback digital signal; EVM calculation module 42 is used to calculate the EVM value of the target radio frequency signal based on the aligned baseband signal and the feedback digital signal; The calibration parameter update module 43 is used to perform minimum mean square error analysis using the EVM value with the goal of minimizing the EVM value, and update the calibration parameter information according to the analysis results, and send the updated calibration parameter information to the pre-calibrator 11.

[0044] Specifically, in the embodiments of this application, the control module may consist of a synchronization and alignment module, an EVM calculation module, and a correction parameter update module connected in sequence. The correction parameter update module can be described as an "adaptive control engine." Through the aforementioned pre-designed connection lines, the synchronization and alignment module can receive the digital baseband signal as a reference signal and the feedback digital signal transmitted from the feedback receiving link, and perform time synchronization and phase rotation alignment on the original baseband reference signal and the feedback digital signal to eliminate the effects of transmission delay and local oscillator phase difference.

[0045] Furthermore, the aligned baseband signal and feedback digital signal are input together into the EVM calculation module for EVM value analysis and calculation, outputting the EVM value of the target RF signal. Then, after receiving this EVM value, the correction parameter update module can use a pre-set adaptive algorithm, such as the Least Mean Square (LMS) algorithm, to minimize the EVM value. It performs minimum mean square error analysis on the EVM value and updates the correction parameter information based on the analysis results. The updated correction parameter information is then sent to the pre-corrector so that if the EVM value is not optimal, the next iteration can be performed. The updated correction parameters are then used to perform joint pre-correction processing on the subsequently transmitted baseband signal, thus forming a closed-loop control based on dynamically adjusting the input to maintain optimal performance.

[0046] The transmitter system of this application embodiment constructs a control module by introducing a synchronization and alignment module, an EVM calculation module and a correction parameter update module connected in sequence. It can continuously compare the reference signal and the feedback signal, and use the EVM error to drive the update of the correction parameters. This enables the system to adaptively track changes in the characteristics of the radio frequency transmission link and continuously adjust its input signal to ensure that the radio frequency signal output is always maintained at the optimal EVM level.

[0047] Continue to refer to Figure 2Based on the above embodiments, as an optional embodiment, the radio frequency transmission link 2 includes an I / Q modulator 21, a power amplifier 22, a coupler 23, and a transmitting antenna 24 connected in sequence. The input terminal of the I / Q modulator 21 is connected to the digital-to-analog converter 12 as the input terminal of the RF transmission link 2, and is used to perform up-conversion processing on the pre-corrected baseband signal to output the original RF signal. Power amplifier 22 is used to amplify the power of the original radio frequency signal and output the target radio frequency signal; The second output terminal of coupler 23 is connected to the first output terminal of RF transmission link 2 and the input terminal of feedback receiving link 3, for acquiring the target RF signal and sending the target RF signal to feedback receiving link 3; The transmitting antenna 24 serves as the second output terminal of the radio frequency transmitting link 2 and is used to transmit the target radio frequency signal.

[0048] Specifically, in the embodiments of this application, a coupler is introduced into the RF transmission link, and the coupler is connected to the output terminal of the power amplifier; the first output terminal of the coupler is connected to the transmitting antenna, and the second output terminal is connected to the input terminal of the feedback receiving link as the first output terminal of the RF transmission link. In this way, after the power amplifier outputs the target RF signal, one path can be transmitted through the transmitting antenna, and the other path can be used to collect the target RF signal through the coupler and send it to the feedback receiving link as a feedback signal to the control module for EVM calculation.

[0049] The transmitter system of this application embodiment introduces a coupler and connects it to the feedback receiving link to form a feedback signal loop, providing a key feedback mechanism and reliable hardware support for the construction of the above-mentioned transmitter closed-loop control system.

[0050] Continue to refer to Figure 2 Based on the above embodiments, as an optional embodiment, the feedback receiving link 3 includes an analog-to-digital converter 31 and a demodulator 32 connected in sequence; the input terminal of the analog-to-digital converter 31 serves as the input terminal of the feedback receiving link 3, and the output terminal of the demodulator 32 serves as the output terminal of the feedback receiving link 3. The analog-to-digital converter 31 is used to receive the target radio frequency signal and process the target radio frequency signal into a corresponding digital signal; Demodulator 32 is used to down-convert the digital signal and output a feedback digital signal.

[0051] Specifically, in the embodiments of this application, the feedback receiving link can be composed of an analog-to-digital converter (ADC) and a demodulator connected in sequence. The input terminal of the ADC serves as the input terminal of the feedback receiving link and can be connected to the output terminal of the coupler in the aforementioned RF transmitting link; the output terminal of the demodulator serves as the output terminal of the feedback receiving link and can be connected to the input terminal of the synchronization and alignment module in the aforementioned control module. In this way, the ADC can receive the target RF signal acquired by the coupler and process it into a corresponding digital signal; the demodulator further performs down-conversion processing on the digital signal and outputs a feedback digital signal, thus achieving signal demodulation, which is then received by the control module for EVM calculation.

[0052] Continue to refer to Figure 2 In one embodiment of this application, the transmitter system includes a digital pre-calibrator, an RF transmit link, a feedback receive link, and a control module. The digital pre-calibrator includes a pre-calibrator and a digital-to-analog converter connected in sequence, and further includes an I / Q defect compensation module and a PA nonlinearity pre-distortion module cascaded in sequence. The control module includes a synchronization and alignment module, an EVM calculation module, and a calibration parameter update module connected in sequence. The RF transmit link includes an I / Q modulator, a power amplifier, a coupler, and a transmit antenna connected in sequence. The feedback receive link includes an analog-to-digital converter and a demodulator connected in sequence. Thus, during transmitter system operation, the digital baseband signal is input to the digital pre-calibrator, processed by the pre-calibrator and the digital-to-analog converter, and output as a pre-calibrated baseband signal. This pre-calibrated baseband signal is then up-converted and power-amplified by the RF transmit link to become the target RF signal, which is then transmitted by the antenna. The coupler branch can acquire the target RF signal, which is then digitized and down-converted by the analog-to-digital converter and demodulator in the feedback receive link before being sent to the synchronization and alignment module in the control module. This module precisely aligns the feedback digital signal with the baseband reference signal in terms of time and phase. The EVM calculation module calculates the EVM values ​​of the two signals after alignment. As a correction parameter update module for the adaptive control engine, it can dynamically adjust the parameters of the digital pre-corrector based on the current EVM value using the LMS algorithm, thereby forming a closed-loop control system that continuously minimizes the EVM.

[0053] Figure 3 This is a schematic diagram of the EVM correction process performed by the EVM correction transmitter system provided in this application embodiment, as shown below. Figure 3 As shown in the embodiments of this application, the EVM calibration process specifically includes the following steps: Step 1, Signal Transmission and Coupling Feedback: The digital baseband signal (I / Q signal) undergoes joint pre-correction processing via a digital pre-corrector, then is up-converted to RF and amplified by the RF transmission link to output the target RF signal. This target RF signal is then acquired via a coupler and digitized and down-converted by the feedback receiving link to obtain the feedback digital signal. This feedback signal represents the final output state of the system.

[0054] Step 2, Synchronization and Alignment of Reference and Feedback Signals: The original baseband signal is used as the reference signal and the feedback digital signal obtained in Step 1 is synchronized in time and phase rotated to eliminate the effects of transmission delay and local oscillator phase difference.

[0055] Step 3, Real-time EVM Calculation and Performance Evaluation: Calculate the EVM value of the current target RF signal in real time based on the aligned reference signal and feedback digital signal.

[0056] Step four, optimizing the decision-making EVM and updating the joint parameters: A joint pre-corrector is established, incorporating I / Q imbalance compensation and PA nonlinearity compensation. The joint pre-correction behavior of this pre-corrector is controlled by correction parameter information, which is a set of adjustable joint parameters. The optimization objective is to minimize the EVM value calculated in step three, and this correction parameter information is dynamically updated using an adaptive algorithm (such as the LMS algorithm or Recursive Least Squares (RLS)). Essentially, this step generates control commands based on the final output quality (EVM) to adjust the predistortion level of the input I / Q signals, thereby achieving closed-loop control based on the output, adjusting the input.

[0057] In the adaptive control engine, the LMS algorithm is specifically implemented as follows: The algorithm's inputs are: the instantaneous error e between the synchronized and aligned reference signal and the feedback digital signal, and the current internal state of the pre-corrector.

[0058] The algorithm output is the update of all adjustable parameters of the joint pre-corrector, i.e., the correction parameter information, including I / Q compensation parameters (control gain, phase, DC offset) and DPD coefficients (predistortion coefficients).

[0059] The parameter adjustment process includes: The algorithm minimizes the squared error e 2 To achieve the goal, fine-tune the parameters along the direction of error reduction. In each iteration, based on the cross-correlation between the current error and the internal signal of the pre-corrector, calculate the adjustment direction and magnitude of each parameter, and then simultaneously update all I / Q compensation parameters and DPD coefficients. For example: (1) If the cross-correlation between the error signal and the I-channel signal is positive, then the gain a of the I-channel should be appropriately reduced; (2) If the error is related to the basis functions of the DPD polynomial, then fine-tune the corresponding polynomial coefficients; (3) The DC offset parameter is adjusted according to the DC component of the error.

[0060] Through this real-time cyclic adjustment, the pre-corrected baseband signal output by the pre-corrector decreases continuously after passing through the RF transmission link, eventually converging to the optimal value.

[0061] Step 5, Closed-loop Iterative Optimization: Continuously repeat steps one through four to form a closed-loop control system. By continuously comparing the baseband signal with the feedback digital signal, and using this error to drive the update of correction parameters, the system can adaptively track changes in the characteristics of the RF transmit link. Through continuous adjustment of the input signal, it ensures that the output always maintains the EVM at the optimal level.

[0062] The method flow of this application embodiment is a continuously running loop process, which ensures the real-time and dynamic nature of EVM correction, effectively solves the problem of dynamic EVM correction, and improves the overall performance of the transmitter.

[0063] The control method of the EVM correction transmitter system provided in this application is described below. The control method of the EVM correction transmitter system described below can be referred to in correspondence with the EVM correction transmitter system based on real-time feedback and predistortion described above.

[0064] Figure 4 This is a flowchart illustrating the control method for the EVM correction transmitter system provided in this application embodiment. It can be understood that it can be applied to any of the aforementioned EVM correction transmitter systems based on real-time feedback and predistortion, such as... Figure 4 As shown, the method includes: Step S1: Receive correction parameter information, perform pre-correction processing on the baseband signal according to the correction parameter information, and output the pre-corrected baseband signal; Step S2: Generate a target radio frequency signal based on the pre-calibrated baseband signal and transmit it, and collect the target radio frequency signal and process the target radio frequency signal into a feedback digital signal; Step S3: Determine the EVM value of the target RF signal based on the baseband signal and the feedback digital signal, and update the correction parameter information with the goal of minimizing the EVM value to adjust the quality of the target RF signal.

[0065] It should be understood that the above method is applied to the EVM correction transmitter system in the above embodiments. The corresponding steps in the method, their implementation principles and technical effects are similar to those described in the relevant modules / units of the above system. The implementation process of this method can refer to the corresponding working process in the above system, and will not be repeated here.

[0066] The control method of the EVM-corrected transmitter system in this application introduces a digital pre-corrector, a feedback receiving link, and a control module. The feedback receiving link couples the RF signal from the transmitter to a feedback digital signal. The control module then synchronizes and aligns the feedback digital signal with the original baseband reference signal. The error vector amplitude (EVM) value is calculated in real time, and the correction parameters of the digital pre-corrector are dynamically updated with minimizing this EVM value as the direct objective. This allows for simultaneous compensation and optimization of I / Q modulator defects and power amplifier nonlinearity, forming a closed-loop control system. This system dynamically tracks changes in RF link characteristics, achieving online real-time optimization and correction of the EVM. It effectively improves the transmitter's performance stability and modulation quality under complex operating environments, overcomes the shortcomings of traditional static calibration methods, reduces reliance on external testing equipment, and lowers the transmitter system cost.

[0067] Based on the above embodiments, as an optional embodiment, pre-calibrating the baseband signal according to the calibration parameter information and outputting the pre-calibrated baseband signal includes: Based on the correction parameter information, the baseband signal is subjected to joint pre-correction processing for I / Q defects and PA nonlinearity, and the joint pre-correction signal is output. The combined pre-calibrated signal is processed by digital-to-analog conversion to output the pre-calibrated baseband signal.

[0068] Based on the above embodiments, as an optional embodiment, the EVM value of the target RF signal is determined based on the baseband signal and the feedback digital signal, and the correction parameter information is updated with the goal of minimizing the EVM value to adjust the quality of the target RF signal, including: Time synchronization and phase rotation alignment are performed on the baseband signal and the feedback digital signal; The EVM value of the target RF signal is calculated based on the aligned baseband signal and the feedback digital signal. With the goal of minimizing the EVM value, minimum mean square error analysis is performed using the EVM value, and the correction parameter information is updated based on the analysis results to adjust the quality of the target RF signal.

[0069] Based on the above embodiments, as an optional embodiment, generating a target radio frequency signal based on the pre-corrected baseband signal and transmitting it includes: The pre-corrected baseband signal is up-converted to output the original radio frequency signal. The original radio frequency signal is amplified to output the target radio frequency signal; The target radio frequency signal is transmitted through the transmitting antenna.

[0070] The method steps in this application embodiment can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside in an ASIC.

[0071] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state disk (SSD)).

[0072] It is understood that the various numerical designations used in the embodiments of this application are merely for the convenience of description and are not intended to limit the scope of the embodiments of this application.

[0073] It should be understood that expressions such as “comprising” and “may include” used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as “comprising” and / or “having” are to be interpreted as indicating a particular characteristic, number, operation, constituent element, component, or combination thereof, but not to exclude the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0074] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A transmitter system based on real-time feedback and predistortion EVM correction, characterized in that, include: The digital precalibrator, RF transmit link, feedback receive link, and control module are connected in sequence. The digital pre-calibrator is also connected to the control module; The digital pre-calibrator is used to receive calibration parameter information sent by the control module and perform pre-calibration processing on the baseband signal according to the calibration parameter information; The radio frequency transmission link is used to generate a target radio frequency signal based on the pre-corrected baseband signal for transmission. The feedback receiving link is used to receive the target radio frequency signal and process the target radio frequency signal into a feedback digital signal; The control module is used to determine the EVM value of the target radio frequency signal based on the baseband signal and the feedback digital signal, and to update the correction parameter information with the goal of minimizing the EVM value, so as to adjust the quality of the target radio frequency signal transmitted by the radio frequency transmission link.

2. The EVM correction transmitter system according to claim 1, characterized in that, The digital pre-calibrator includes a pre-calibrator and a digital-to-analog converter connected in sequence; The first input terminal of the pre-calibrator serves as the first input terminal of the digital pre-calibrator, used to receive the baseband signal; the second input terminal of the pre-calibrator serves as the second input terminal of the digital pre-calibrator, used to receive the calibration parameter information. The output of the digital-to-analog converter serves as the output of the digital pre-corrector. The pre-corrector is used to perform joint pre-correction processing on the baseband signal for I / Q defects and PA nonlinearity based on the correction parameter information, and outputs a joint pre-correction signal; The digital-to-analog converter is used to perform digital-to-analog conversion processing on the joint pre-correction signal and output the pre-corrected baseband signal.

3. The EVM correction transmitter system according to claim 2, characterized in that, The pre-corrector includes an I / Q defect compensation module and a PA nonlinearity pre-distortion module cascaded in sequence. The I / Q defect compensation module is used to correct the I / Q amplitude distortion, I / Q phase error and I / Q DC offset of the I / Q modulator in the RF transmission link. The PA nonlinearity pre-distortion module is used to correct the PA nonlinearity distortion of the power amplifier in the RF transmission link. The correction parameter information includes parameters for compensating for I / Q amplitude distortion, I / Q phase error, and I / Q DC offset, as well as pre-distortion coefficients for PA nonlinear distortion compensation.

4. The EVM correction transmitter system according to claim 2, characterized in that, The control module includes a synchronization and alignment module, an EVM calculation module, and a correction parameter update module connected in sequence. The input terminal of the synchronization and alignment module serves as the input terminal of the control module, and the output terminal of the correction parameter update module serves as the output terminal of the control module, which is connected to the second input terminal of the pre-corrector. The synchronization and alignment module is used to perform time synchronization and phase rotation alignment processing on the baseband signal and the feedback digital signal; The EVM calculation module is used to calculate the EVM value of the target radio frequency signal based on the aligned baseband signal and the feedback digital signal; The correction parameter update module is used to perform minimum mean square error analysis using the EVM value with the goal of minimizing the EVM value, update the correction parameter information according to the analysis results, and send the updated correction parameter information to the pre-corrector.

5. The EVM correction transmitter system according to claim 2, characterized in that, The radio frequency transmission link includes an I / Q modulator, a power amplifier, a coupler, and a transmitting antenna connected in sequence; The input terminal of the I / Q modulator is connected to the digital-to-analog converter as the input terminal of the radio frequency transmission link, and is used to perform up-conversion processing on the pre-corrected baseband signal to output the original radio frequency signal. The power amplifier is used to amplify the power of the original radio frequency signal and output the target radio frequency signal; The second output terminal of the coupler is connected to the first output terminal of the radio frequency transmission link and the input terminal of the feedback receiving link, for acquiring the target radio frequency signal and sending the target radio frequency signal to the feedback receiving link; The transmitting antenna serves as the second output terminal of the radio frequency transmission link and is used to transmit the target radio frequency signal.

6. The EVM correction transmitter system according to any one of claims 1-5, characterized in that, The feedback receiving link includes an analog-to-digital converter and a demodulator connected in sequence; the input terminal of the analog-to-digital converter serves as the input terminal of the feedback receiving link, and the output terminal of the demodulator serves as the output terminal of the feedback receiving link. The analog-to-digital converter is used to receive the target radio frequency signal and process the target radio frequency signal into a corresponding digital signal; The demodulator is used to perform down-conversion processing on the digital signal and output the feedback digital signal.

7. A control method applied to an EVM-corrected transmitter system based on real-time feedback and predistortion as described in any one of claims 1-6, characterized in that, include: Receive correction parameter information, perform pre-correction processing on the baseband signal according to the correction parameter information, and output the pre-corrected baseband signal; The target radio frequency signal is generated and transmitted based on the pre-corrected baseband signal, and the target radio frequency signal is collected and processed into a feedback digital signal. The EVM value of the target RF signal is determined based on the baseband signal and the feedback digital signal, and the correction parameter information is updated with the goal of minimizing the EVM value to adjust the quality of the target RF signal.

8. The control method according to claim 7, characterized in that, The step of pre-correcting the baseband signal according to the correction parameter information and outputting the pre-corrected baseband signal includes: Based on the correction parameter information, the baseband signal is subjected to joint pre-correction processing for I / Q defects and PA nonlinearity, and a joint pre-correction signal is output. The joint pre-corrected signal is subjected to digital-to-analog conversion processing to output the pre-corrected baseband signal.

9. The control method according to claim 8, characterized in that, The step of determining the EVM value of the target RF signal based on the baseband signal and the feedback digital signal, and updating the correction parameter information with the goal of minimizing the EVM value to adjust the quality of the target RF signal, includes: The baseband signal and the feedback digital signal are subjected to time synchronization and phase rotation alignment processing; The EVM value of the target radio frequency signal is calculated based on the aligned baseband signal and the feedback digital signal; With the goal of minimizing the EVM value, minimum mean square error analysis is performed using the EVM value, and the correction parameter information is updated based on the analysis results to adjust the quality of the target radio frequency signal.

10. The control method according to claim 8, characterized in that, The step of generating a target radio frequency signal based on the pre-corrected baseband signal and transmitting it includes: The pre-corrected baseband signal is up-converted to output the original radio frequency signal; The original radio frequency signal is amplified to output the target radio frequency signal; The target radio frequency signal is transmitted through the transmitting antenna.

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