IQ imbalance estimation value acquisition method based on single-tone detection

Abstract

The invention relates to an IQ imbalance estimation value obtaining method based on single-tone detection, and the method comprises the steps: receiving a fixed-frequency single-tone signal through a zero-intermediate-frequency receiver, and obtaining the basic parameters of the fixed-frequency single-tone signal; performing first processing on the fixed-frequency single-tone signal to obtain a corresponding digital baseband single-tone signal; performing second processing on the digital baseband single-tone signal to obtain the digital baseband single-tone signal after compensation of the received direct current bias; performing truncation processing on the digital baseband single-tone signal after compensation of the received direct current bias to obtain a truncated digital baseband single-tone signal; and obtaining I-path and Q-path frequency domain signals of the truncated digital baseband single-tone signal according to the truncated digital baseband single-tone signal, and obtaining an IQ phase imbalance estimated value and an IQ amplitude imbalance estimated value according to the I-path and Q-path frequency domain signals. The method provided by the invention solves the problems of low accuracy and high complexity of the IQ imbalance estimation value in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless communications, and in particular to a method for obtaining an IQ imbalance estimation value based on single-tone detection. Background Art

[0002] As a wireless receiver technology, the zero-IF receiver architecture has a simple structure, high integration, and low power consumption compared to the superheterodyne receiver architecture. It has been widely used in communication systems such as mobile communications, wireless broadcast communications, and radar communications.

[0003] Although zero-IF receivers have many advantages, they also have some inherent defects due to the limitations of the RF circuit structure. For example, poor isolation of RF devices leads to leakage of the local oscillator, resulting in a DC bias in reception, inconsistent amplitude gain between the in-phase branch and the orthogonal branch of the local oscillator signal, and the phase does not meet the orthogonal relationship, resulting in IQ imbalance, which will reduce the dynamic range of the receiver and seriously affect the system's reception performance. Compared with the DC bias in reception, the IQ imbalance problem is more difficult to solve.

[0004] The IQ imbalance suppression method mainly includes the following two aspects: First, optimize the RF circuit structure. This method is triggered from the root cause of the IQ imbalance problem and uses RF devices with higher isolation and better consistency, but the circuit cost increases; second, use digital IQ imbalance estimation and compensation technology. This method overcomes the inherent defects of the RF circuit through digital signal processing and can effectively reduce costs, but the estimation accuracy is low.

[0005] Therefore, there is an urgent need for a method for obtaining an IQ imbalance estimation value based on single tone detection. Summary of the invention

[0006] 1. Technical issues to be resolved In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a method for obtaining an IQ imbalance estimation value based on single-tone detection, which solves the technical problems of high circuit cost and low accuracy of the IQ imbalance suppression method in the prior art.

[0007] (II) Technical solution In order to achieve the above object, the main technical solutions adopted by the present invention include: An embodiment of the present invention provides a method for obtaining an IQ imbalance estimation value based on single-tone detection, comprising: S100, a zero intermediate frequency receiver receives a fixed frequency single tone signal generated by a wireless communication system, and obtains basic parameters of the fixed frequency single tone signal; performs a first process on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of the fixed frequency single tone signal include frequency and duration; S200, the zero intermediate frequency receiver performs a second processing on the digital baseband single-tone signal, obtains a receiving DC offset value of the digital baseband single-tone signal, and performs DC offset compensation on the digital baseband single-tone signal according to the receiving DC offset value to obtain a digital baseband single-tone signal after the receiving DC offset is compensated; S300, the zero intermediate frequency receiver truncates the digital baseband single tone signal after the compensation reception DC bias to obtain a truncated digital baseband single tone signal; S400, the zero intermediate frequency receiver obtains the I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal according to the truncated digital baseband single-tone signal, and obtains the IQ phase imbalance estimation value and the IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency domain signals.

[0008] Optionally, the method further comprises: S500: The zero intermediate frequency receiver performs IQ imbalance compensation and calibration internally according to the acquired IQ phase imbalance estimation value and IQ amplitude imbalance estimation value, thereby obtaining a calibrated zero intermediate frequency receiver to be tested.

[0009] Optionally, in S100, performing a first process on the fixed frequency single tone signal includes: The fixed frequency single tone signal is subjected to down-conversion, analog low-pass filtering and analog-to-digital conversion processing to obtain a digital baseband single tone signal corresponding to the fixed frequency single tone signal.

[0010] Optionally, the S300 includes: S310, searching for all zero-crossing positions and indexes of the I and Q paths of the digital baseband single-tone signals after receiving and compensating the DC bias; sorting the zero-crossing position indexes of the I and Q paths from small to large, and obtaining an arranged zero-crossing position index sequence of the I and Q paths; S320, using the arranged zero-crossing position index sequences of the I path and the Q path to perform truncation processing on the digital baseband single-tone signal after compensation of the received DC bias, to obtain the truncated digital baseband single-tone signal.

[0011] Optionally, the S310 includes: Search for the zero crossing position of the I and Q paths of the digital baseband single tone signal after compensation for the DC bias, and compare the I and Q paths of the digital baseband single tone signal after compensation for the DC bias. With adjacent amplitude The size of Greater than zero and Less than or equal to zero, or Less than zero and If it is greater than or equal to zero, the position is the zero-crossing position, and the index of the zero-crossing position is obtained.

[0012] Optionally, the S320 includes: Substitute the digital baseband single tone signal after compensating the received DC offset into the following formula to obtain the truncated digital baseband single tone signal: ; in, is the truncated digital baseband single tone signal, To compensate for the digital baseband single tone signal after receiving DC bias, Z0 is the minimum zero-crossing position index of the zero-crossing position of the I-way, and T A To compensate for the period of the digital baseband single tone signal after receiving the DC bias, the value is twice as large as the average value of the zero-crossing position index difference obtained by performing differential calculation and arithmetic averaging on the zero-crossing position index sequences of the I and Q paths.

[0013] Optionally, the S400 includes: S410, input the truncated digital baseband single tone signal into the following formula to obtain the I-channel and Q-channel frequency domain signals of the truncated digital baseband single tone signal: ; ; Where k is the frequency domain index, k=0,1,2,…,T A -1; for I Road, for Q Road, T A To compensate for the period of the digital baseband tone signal after receiving DC bias, F I (k) is the frequency domain signal of channel I, F Q (k) is the Q-path frequency domain signal, j is the imaginary unit, and n is the time index.

[0014] Optionally, the S400 further includes: S420, acquiring frequency domain signals corresponding to respective maximum values ​​of the modulus values ​​in the I-channel and Q-channel frequency domain signals according to the truncated digital baseband single-tone signal; S430, input the frequency domain signals corresponding to the maximum modulus values ​​in the I-channel and Q-channel frequency domain signals into the following formula to obtain an IQ amplitude imbalance estimation value: ; in, is the estimated value of IQ magnitude imbalance, is the frequency domain signal corresponding to the maximum value of the modulus value in the I-channel frequency domain signal, It is the frequency domain signal corresponding to the maximum modulus value in the Q-path frequency domain signal.

[0015] Optionally, the S400 further includes: S440, inputting the I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal into the following formula to obtain an IQ phase imbalance estimation value: ; in, is the estimated value of IQ phase imbalance, F I (k) is the frequency domain signal of channel I, F Q (k) is the frequency domain signal of Q path, k max is the position index corresponding to the maximum value of the I-channel and Q-channel frequency domain signal modulus values, and arg is the principal value of the complex angle.

[0016] In a second aspect, an embodiment of the present invention provides a wireless communication system, including: Antenna module, zero intermediate frequency receiver; The antenna module is used to generate a fixed frequency single tone signal; The zero intermediate frequency receiver is used to receive a fixed frequency single tone signal generated by a wireless communication system and obtain basic parameters of the fixed frequency single tone signal; perform a first processing on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of the fixed frequency single tone signal include frequency and duration; The zero intermediate frequency receiver is also used to perform a second processing on the digital baseband single-tone signal, obtain a received DC offset value of the digital baseband single-tone signal, and perform DC offset compensation on the digital baseband single-tone signal according to the received DC offset value to obtain a digital baseband single-tone signal after the received DC offset is compensated; The zero intermediate frequency receiver is also used to perform truncation processing on the digital baseband single tone signal after the compensation reception DC bias, and obtain the truncated digital baseband single tone signal; The zero intermediate frequency receiver is also used to obtain I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal according to the truncated digital baseband single-tone signal, and obtain an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency domain signals.

[0017] (III) Beneficial effects The beneficial effects of the present invention are as follows: the present invention is a method for obtaining an IQ imbalance estimation value based on single-tone detection, which uses the characteristics of a single-tone signal to perform IQ imbalance estimation, compensates for the received DC bias through the received DC bias estimation value of the digital baseband single-tone signal, reduces the influence of the received DC bias on the IQ imbalance estimation, suppresses spectrum leakage by truncation processing of the digital baseband single-tone signal, obtains the characteristics of the digital baseband single-tone signal by calculating the I-path and Q-path frequency domain signals of the digital baseband single-tone signal, calculates the IQ amplitude imbalance estimation value and the IQ phase imbalance estimation value, and finally realizes simple, efficient and highly accurate IQ imbalance estimation, facilitates accurate compensation and calibration of IQ imbalance, improves receiving performance, and saves system cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a flow chart of a method for obtaining an IQ imbalance estimation value based on single-tone detection according to Embodiment 1 of the present invention; Figure 2 A flowchart of a method for obtaining an IQ imbalance estimation value based on single tone detection according to Embodiment 2 of the present invention; Figure 3 for Figure 2 A continuation of a flowchart of a method for obtaining an IQ imbalance estimation value based on single tone detection, namely, process A; Figure 4 for Figure 3 The continuation of is process B. DETAILED DESCRIPTION

[0019] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0020] An embodiment of the present invention proposes a method for obtaining an IQ imbalance estimation value based on single-tone detection. In order to solve the technical problems of high circuit cost and low accuracy of the IQ imbalance suppression method in the prior art, the present invention uses the characteristics of a single-tone signal to perform IQ imbalance estimation, calculates a received DC bias estimation value of a digital baseband single-tone signal, compensates for the received DC bias, reduces the influence of the received DC bias on the IQ imbalance estimation, truncates the digital baseband single-tone signal, suppresses spectrum leakage, calculates the I-path and Q-path frequency domain signals of the digital baseband single-tone signal, obtains the characteristics of the digital baseband single-tone signal, calculates the IQ amplitude imbalance estimation value and the IQ phase imbalance estimation value, and finally realizes simple and efficient IQ imbalance estimation, facilitates accurate IQ imbalance compensation and calibration, improves receiving performance, and saves system cost.

[0021] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0022] See also Figure 1 , a method for obtaining an IQ imbalance estimation value based on single tone detection according to an embodiment of the present invention comprises: Step S100, the zero intermediate frequency receiver receives a fixed frequency single tone signal generated by a wireless communication system, and obtains basic parameters of the fixed frequency single tone signal; performs a first processing on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of the fixed frequency single tone signal include frequency and duration; Step S200: The zero intermediate frequency receiver performs a second processing on the digital baseband tone signal, obtains a receiving DC offset value of the digital baseband tone signal, and performs DC offset compensation on the digital baseband tone signal according to the receiving DC offset value to obtain a digital baseband tone signal after the receiving DC offset is compensated; Step S300: The zero intermediate frequency receiver performs truncation processing on the digital baseband single tone signal after the compensation reception DC bias, and obtains the truncated digital baseband single tone signal; Step S400: The zero intermediate frequency receiver obtains I and Q frequency domain signals of the truncated digital baseband tone signal according to the truncated digital baseband tone signal, and obtains an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I and Q frequency domain signals.

[0023] In step S200, the received DC offset estimation value of the digital baseband single tone signal is calculated, and the received DC offset of the digital baseband single tone signal is compensated, which can solve the problem that the received DC offset caused by the local oscillator leakage of the zero intermediate frequency receiver affects the receiving demodulation performance, thereby eliminating the influence of the DC offset on the IQ imbalance estimation.

[0024] In step S300, before calculating the I-path and Q-path frequency domain signals of the digital baseband tone signal, a zero-crossing detection method is used to calculate the period of the digital baseband tone signal, and the digital baseband tone signal of a complete period is intercepted using the zero-crossing position, which can suppress the spectrum leakage caused by Fourier transform.

[0025] In this embodiment, through the above method, simple and efficient IQ imbalance estimation can be achieved, thereby achieving accurate IQ imbalance compensation and calibration, improving the reception performance of the zero intermediate frequency receiver, and saving system costs.

[0026] A method for obtaining an IQ imbalance estimation value based on single-tone detection according to an embodiment of the present invention includes: Step S100, the zero intermediate frequency receiver receives a fixed frequency single tone signal generated by a wireless communication system, and obtains basic parameters of the fixed frequency single tone signal; performs a first processing on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of a fixed-frequency tone signal include frequency and duration; Step S200: The zero intermediate frequency receiver performs a second processing on the digital baseband tone signal, obtains a receiving DC offset value of the digital baseband tone signal, and performs DC offset compensation on the digital baseband tone signal according to the receiving DC offset value to obtain a digital baseband tone signal after the receiving DC offset is compensated; Step S300: The zero intermediate frequency receiver performs truncation processing on the digital baseband single tone signal after the compensation reception DC bias, and obtains the truncated digital baseband single tone signal; Step S400: The zero intermediate frequency receiver obtains I and Q frequency domain signals of the truncated digital baseband tone signal according to the truncated digital baseband tone signal, and obtains an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I and Q frequency domain signals.

[0027] Specifically, the fixed frequency single tone signal is an ideal baseband complex single tone signal with the same frequency and intersecting phases in the I and Q channels. Assuming that the ideal baseband complex single tone signal is x(t), the fixed frequency single tone signal is also x(t), and x(t) can be expressed as: ; Among them, f A is the frequency of the fixed frequency single tone signal, t A is the duration of a fixed-frequency tone signal, and j is an imaginary unit.

[0028] In this embodiment, the method further includes: Step S500: The zero intermediate frequency receiver performs IQ imbalance compensation and calibration internally according to the acquired IQ phase imbalance estimation value and IQ amplitude imbalance estimation value, thereby obtaining a calibrated zero intermediate frequency receiver to be tested.

[0029] In step S100, performing a first process on the fixed frequency single tone signal includes: The fixed frequency single tone signal is subjected to down-conversion, analog low-pass filtering and analog-to-digital conversion processing to obtain a digital baseband single tone signal corresponding to the fixed frequency single tone signal.

[0030] Assuming that the digital baseband tone signal corresponding to the fixed frequency tone signal is r(n), r(n) can be expressed as: ; Where n=0,1,2,…,N-1, N is the length of r(n), r I (n) is the I path of r(n), r Q (n) is the Q path of r(n), ε is the IQ amplitude imbalance value, θ is the IQ phase imbalance value, and noise interference is negligible.

[0031] In this embodiment, in step S200, DC offset compensation is performed on the digital baseband tone signal according to the received DC offset value to obtain the digital baseband tone signal after the received DC offset is compensated, which includes: Input the receiving DC offset value of the digital baseband single tone signal into the following formula to obtain the digital baseband single tone signal after compensating the receiving DC offset: ; Where r(n) is the digital baseband single tone signal, h0 is the received DC bias value, is a complex constant, N is the length of r(n), S is the sliding window step size, l is the sliding window factor, To compensate for the digital baseband single tone signal after receiving DC bias; The received DC offset value of the digital baseband single-tone signal is obtained by using a sliding window averaging method.

[0032] Specifically, the method of obtaining the receiving DC offset value of the digital baseband single tone signal by using the sliding window averaging method specifically includes: Assume that the sliding window length is W=LS, where S is the sliding window step size, L is the sliding window factor, and L is an integer.

[0033] Before the sliding window slides for the first time, the amplitude of the digital baseband tone signal r(n) in the sliding window is accumulated, and the arithmetic mean of the accumulated digital baseband tone signal amplitude is calculated cycle by cycle with the sliding window step length S as the calculation period to obtain the received DC offset estimation value h( l ), which can be expressed as: ; Among them, S is the sliding window step size, L is the sliding window factor, and r(n) is the digital baseband single tone signal.

[0034] When the number of accumulated digital baseband signal amplitudes reaches the sliding window length W, the sliding window starts to slide, and the sliding window step length S is used as the calculation cycle. The arithmetic mean of the amplitude of the digital baseband single tone signal within the current sliding window length W is calculated cycle by cycle to obtain the received DC offset estimation value h ( l ), which can be expressed as: ; ; in, for Round down.

[0035] Through the above method, the receiving DC bias in the digital baseband single-tone signal is accurately measured and stepped, thereby eliminating or significantly reducing the influence of the bias on subsequent signal processing and analysis. Specifically, this step can ensure that the average value of the signal is close to the ideal zero point, avoid the demodulation error caused by the DC component, and improve the accuracy of signal demodulation.

[0036] In the specific implementation process, step S300 includes: Step S310, searching for all zero-crossing positions and indexes of the I and Q paths of the digital baseband single-tone signals after receiving and compensating the DC bias; sorting the zero-crossing position indexes of the I and Q paths from small to large, and obtaining an arranged zero-crossing position index sequence of the I and Q paths; Step S320: Using the arranged zero-crossing position index sequences of the I path and the Q path, truncation processing is performed on the digital baseband single-tone signal after compensation of the received DC offset to obtain the truncated digital baseband single-tone signal.

[0037] Step S310 includes: Search for the zero crossing position of the I and Q paths of the digital baseband single tone signal after compensation for the DC bias, and compare the I and Q paths of the digital baseband single tone signal after compensation for the DC bias. With adjacent amplitude The size of Greater than zero and Less than or equal to zero, or Less than zero and If it is greater than or equal to zero, the position is the zero-crossing position, and the index of the zero-crossing position is obtained.

[0038] Step S320 includes: Substitute the digital baseband single tone signal after compensating the received DC offset into the following formula to obtain the truncated digital baseband single tone signal: ; in, is the truncated digital baseband single tone signal, To compensate for the digital baseband single tone signal after receiving DC bias, Z0 is the minimum zero-crossing position index of the zero-crossing position of the I-way, and T A To compensate for the period of the digital baseband single tone signal after receiving the DC bias, the value is twice as large as the average value of the zero-crossing position index difference obtained by performing differential calculation and arithmetic averaging on the zero-crossing position index sequences of the I and Q paths.

[0039] Further, the period T of the digital baseband single tone signal after compensating the DC bias of the reception is obtained. A The specific steps are: The zero-crossing position index sequences of the arranged I and Q paths are differentially calculated to obtain the zero-crossing position index differential sequence, which can be expressed as: ; ; in, is the index difference sequence of I passing through zero position, z I (m) is the index sequence of the zero position where I passes through, is the index difference sequence of Q passing through zero position, z Q (m) is the index sequence of Q passing through the zero position, and m is an index variable used to represent each element in the sequence.

[0040] Next, the arithmetic mean of the zero-crossing position index difference sequence is calculated to obtain the average value of the zero-crossing position index difference, which can be expressed as: ; Then the period T of the digital baseband tone signal after receiving DC bias is compensated A It can be expressed as: ; In this embodiment, step S400 includes: Step S410: Input the truncated digital baseband tone signal into the following formula to obtain the I-channel and Q-channel frequency domain signals of the truncated digital baseband tone signal: ; ; Where k is the frequency domain index, k=0,1,2,…,T A -1; for I Road, for Q Road, T A To compensate for the period of the digital baseband tone signal after receiving DC bias, F I (k) is the frequency domain signal of channel I, F Q (k) is the Q-path frequency domain signal, j is the imaginary unit, and n is the time index.

[0041] Step S420, obtaining frequency domain signals corresponding to the maximum modulus values ​​in the I-path and Q-path frequency domain signals according to the truncated digital baseband single-tone signal; In the specific implementation process, the maximum value of the frequency domain signal modulus of the I and Q channels is searched. and , wait until the maximum value of the modulus is indexed k max ,but and It can be expressed as: ; ; Step S430: Input the frequency domain signals corresponding to the maximum modulus values ​​in the I-channel and Q-channel frequency domain signals into the following formula to obtain an IQ amplitude imbalance estimation value: ; in, is the estimated value of IQ magnitude imbalance, is the frequency domain signal corresponding to the maximum value of the modulus value in the I-channel frequency domain signal, It is the frequency domain signal corresponding to the maximum modulus value in the Q-path frequency domain signal.

[0042] Step S440: Input the I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal into the following formula to obtain an IQ phase imbalance estimation value: ; in, is the estimated value of IQ phase imbalance, F I (k) is the frequency domain signal of channel I, F Q (k) is the frequency domain signal of Q path, k max is the position index corresponding to the maximum value of the I-channel and Q-channel frequency domain signal modulus values, and arg is the principal value of the complex angle.

[0043] The single-tone detection-based IQ imbalance estimation value acquisition method of this embodiment acts on the demodulated output signal of the entire wireless communication system and is applicable to application scenarios of internal IQ imbalance compensation and calibration in various zero intermediate frequency receivers.

[0044] Furthermore, the wireless communication system on which the method of the present invention acts may be a mobile communication terminal device, an Internet of Things node, a satellite communication system, etc.

[0045] In this embodiment, a method for obtaining an IQ imbalance estimation value based on single-tone detection can be used to perform a one-time calibration before the zero intermediate frequency receiver is put into use, that is, during the production process of the zero intermediate frequency receiver, the manufacturer can perform a comprehensive IQ imbalance calibration before leaving the factory. This is usually performed in a controlled environment using a standard signal source, with the purpose of ensuring that each device has the highest possible performance when it leaves the production line.

[0046] In addition, when the zero intermediate frequency receiver is initially installed or deployed, the method of the present invention can be executed to perform IQ imbalance calibration, thereby solving the problem that environmental factors (such as temperature, humidity, etc.) may affect the characteristics of the zero intermediate frequency receiver and cause deviations from factory settings.

[0047] After the zero intermediate frequency receiver is put into use, the IQ imbalance estimation value acquisition method based on single tone detection of the present invention can also be used to maintain the optimal performance of the system by utilizing the communication idle period or a specific maintenance window period. For certain application scenarios with high performance requirements, such as military communications or precision scientific instruments, the zero intermediate frequency receiver will continuously monitor the IQ imbalance and dynamically adjust the compensation parameters according to the real-time measurement results. This method can cope with drift problems caused by environmental changes or long-term use, and ensure long-term stable operation.

[0048] In actual applications, if the working environment of the zero-IF receiver is relatively stable and the requirements for IQ imbalance are not extremely stringent, then only a one-time calibration is required in the early stage. For systems with large changes in working conditions and the need to maintain high accuracy for a long time, it is more appropriate to adopt a continuous monitoring and adjustment method to ensure that the optimal IQ balance state is always maintained.

[0049] The present invention uses the characteristics of a single-tone signal to perform IQ imbalance estimation, calculates a receiving DC bias estimation value of a digital baseband single-tone signal, compensates for the receiving DC bias, reduces the influence of the receiving DC bias on the IQ imbalance estimation, performs truncation processing on the digital baseband single-tone signal, suppresses spectrum leakage, calculates I-path and Q-path frequency domain signals of the digital baseband single-tone signal, obtains the characteristics of the digital baseband single-tone signal, calculates an IQ amplitude imbalance estimation value and an IQ phase imbalance estimation value, and finally realizes simple and efficient IQ imbalance estimation, facilitates accurate IQ imbalance compensation and calibration, improves receiving performance, and saves system cost.

[0050] In this embodiment, a method for obtaining an IQ imbalance estimation value based on single-tone detection is applied to the wireless physical layer of the dual-mode communication protocol of the power user power consumption information collection system. The system architecture used refers to the wireless physical layer part of the "Dual-mode Communication Interconnection Technical Specification Part 4-1: Physical Layer Communication Protocol" issued by the State Grid. The communication frequency used by the system RF antenna is f c =471MHz, the zero-IF receiver analog-to-digital converter has 12 bits and the sampling rate is F S =2.083MHz, the frequency of the fixed frequency single tone signal is f A =8kHz, the new length of the fixed frequency tone is N=10000, and the frequency and length of the fixed frequency tone signal meet the condition f A ≥F S / N. The sliding window length W = 2048, the sliding window step size S = 1024, the sliding window factor L = 2, and the default value of the receiving DC bias h (0) = 0.

[0051] See also Figure 2 , Figure 3 and Figure 4, the specific steps of the method are as follows: (1) The zero-IF receiver receives the fixed-frequency single-tone signal generated by the wireless communication system and obtains the basic parameters of the fixed-frequency single-tone signal. The received fixed-frequency single-tone signal is subjected to IQ mixing through the local oscillator signal, and after low-pass filtering and analog-to-digital conversion, the received digital baseband single-tone signal r(n) is sampled.

[0052] (2) The sliding window averaging method is used. The sliding window step size S is used as the receiving DC offset calculation and compensation period. The amplitude of r(n) in the sliding window is accumulated. The arithmetic mean of the accumulated amplitude of r(n) is calculated period by period to obtain the receiving DC offset estimation value h( l ). Using h( l ) compensates the receiving DC offset of r(n) cycle by cycle to obtain the digital baseband signal after receiving DC offset compensation .

[0053] (3) Using the zero-crossing detection method, compare I Road Adjacent Amplitude and ,as well as Q Road Adjacent Amplitude and Size, Finish and Search and sort the zero-crossing positions to obtain the zero-crossing position index sequence z of path I I (m) and Q pass through the zero position index sequence z Q (m). For z I (m) and z Q (m) Perform differential calculation to obtain the zero-crossing position index differential sequence and .calculate and The arithmetic mean of the zero-crossing position index difference is obtained. , and then get the period T of the digital baseband single tone signal A . With a length of T A The cut-off window for Perform truncation processing, the starting position of the truncation window is z I The first index Z0 of (m) obtains the truncated digital baseband single tone signal .

[0054] (4) Calculation by FFT The I and Q frequency domain signals F I (k) and F Q (k), search for F I (k) and FQ (k) Maximum value of modulus and , get the maximum modulus position index k max .calculate and The ratio of IQ amplitude imbalance is obtained Calculate F I (k) and F Q (k) when k=k max The phase difference at the point is used to obtain the estimated IQ phase imbalance value. .

[0055] Through the above method, the accuracy and reliability of IQ imbalance estimation can be improved while meeting the requirements of low power consumption and low latency, effectively saving the cost of zero intermediate frequency receivers.

[0056] Furthermore, an embodiment of the present invention also includes a wireless communication system, including: Antenna module, zero intermediate frequency receiver; The antenna module is used to generate a fixed frequency single tone signal; The zero intermediate frequency receiver is used to receive a fixed frequency single tone signal generated by a wireless communication system and obtain basic parameters of the fixed frequency single tone signal; perform a first processing on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of a fixed-frequency tone signal include frequency and duration; The zero intermediate frequency receiver is also used to perform a second processing on the digital baseband single-tone signal, obtain a received DC offset value of the digital baseband single-tone signal, and perform DC offset compensation on the digital baseband single-tone signal according to the received DC offset value to obtain a digital baseband single-tone signal after the received DC offset is compensated; The zero intermediate frequency receiver is also used to perform truncation processing on the digital baseband single tone signal after compensating the DC bias of the reception, so as to obtain the truncated digital baseband single tone signal; The zero intermediate frequency receiver is also used to obtain I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal according to the truncated digital baseband single-tone signal, and to obtain an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency domain signals.

[0057] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0058] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0060] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0061] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for obtaining an IQ imbalance estimation value based on single tone detection, characterized in that: include: S100, a zero intermediate frequency receiver receives a fixed frequency single tone signal generated by a wireless communication system, and obtains basic parameters of the fixed frequency single tone signal; Performing a first process on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of the fixed frequency single tone signal include frequency and duration; S200, the zero intermediate frequency receiver performs a second processing on the digital baseband single-tone signal, obtains a receiving DC offset value of the digital baseband single-tone signal, and performs DC offset compensation on the digital baseband single-tone signal according to the receiving DC offset value to obtain a digital baseband single-tone signal after the receiving DC offset is compensated; S300, the zero intermediate frequency receiver truncates the digital baseband single tone signal after the compensation reception DC bias to obtain a truncated digital baseband single tone signal; S400, the zero intermediate frequency receiver obtains the I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal according to the truncated digital baseband single-tone signal, and obtains the IQ phase imbalance estimation value and the IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency domain signals.

2. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 1, characterized in that: The method further comprises: S500: The zero intermediate frequency receiver performs IQ imbalance compensation and calibration internally according to the acquired IQ phase imbalance estimation value and IQ amplitude imbalance estimation value, thereby obtaining a calibrated zero intermediate frequency receiver to be tested.

3. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 1, characterized in that: In S100, performing a first process on the fixed frequency single tone signal includes: The fixed frequency single tone signal is subjected to down-conversion, analog low-pass filtering and analog-to-digital conversion processing to obtain a digital baseband single tone signal corresponding to the fixed frequency single tone signal.

4. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 1, characterized in that: The S300 includes: S310, searching for all zero-crossing positions and indexes of the I and Q paths of the digital baseband single-tone signals after receiving and compensating the DC bias; sorting the zero-crossing position indexes of the I and Q paths from small to large, and obtaining an arranged zero-crossing position index sequence of the I and Q paths; S320, using the arranged zero-crossing position index sequence of the I path and the Q path to perform truncation processing on the digital baseband single-tone signal after compensation of the received DC bias, to obtain the truncated digital baseband single-tone signal.

5. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 4, characterized in that: The S310 includes: Search for the zero crossing position of the I and Q paths of the digital baseband single tone signal after compensation for the DC bias, and compare the I and Q paths of the digital baseband single tone signal after compensation for the DC bias. With adjacent amplitude The size of Greater than zero and Less than or equal to zero, or Less than zero and If it is greater than or equal to zero, the position is the zero-crossing position, and the index of the zero-crossing position is obtained.

6. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 4, characterized in that: The S320 includes: Substitute the digital baseband single tone signal after compensating the received DC offset into the following formula to obtain the truncated digital baseband single tone signal: ； in, is the truncated digital baseband single tone signal, To compensate for the digital baseband single tone signal after receiving DC bias, Z0 is the minimum zero-crossing position index of the zero-crossing position of the I-way, and T A To compensate for the period of the digital baseband single tone signal after receiving the DC bias, the value is twice as large as the average value of the zero crossing position index difference obtained by performing differential calculation and arithmetic averaging on the zero crossing position index sequences of the I path and the Q path.

7. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 1, characterized in that: The S400 includes: S410, input the truncated digital baseband single tone signal into the following formula to obtain the I-channel and Q-channel frequency domain signals of the truncated digital baseband single tone signal: ； ； Where k is the frequency domain index, k=0,1,2,…,T A -1; for I Road, for Q Road, T A To compensate for the period of the digital baseband tone signal after receiving DC bias, F I (k) is the frequency domain signal of channel I, F Q (k) is the Q-path frequency domain signal, j is the imaginary unit, and n is the time index.

8. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 7, characterized in that: The S400 further includes: S420, acquiring frequency domain signals corresponding to respective maximum values ​​of the modulus values ​​in the I-channel and Q-channel frequency domain signals according to the truncated digital baseband single-tone signal; S430, input the frequency domain signals corresponding to the maximum modulus values ​​in the I-channel and Q-channel frequency domain signals into the following formula to obtain an IQ amplitude imbalance estimation value: ； in, is the estimated value of IQ magnitude imbalance, is the frequency domain signal corresponding to the maximum value of the modulus value in the I-channel frequency domain signal, It is the frequency domain signal corresponding to the maximum modulus value in the Q-path frequency domain signal.

9. The method for obtaining an IQ imbalance estimation value based on single tone detection according to claim 8, characterized in that: The S400 further includes: S440, inputting the I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal into the following formula to obtain an IQ phase imbalance estimation value: ； in, is the estimated value of IQ phase imbalance, F I (k) is the frequency domain signal of channel I, F Q (k) is the frequency domain signal of Q path, k max is the position index corresponding to the maximum value of the I-channel and Q-channel frequency domain signal modulus values, and arg is the principal value of the complex angle.

10. A wireless communication system, characterized in that: include: Antenna module, zero intermediate frequency receiver; The antenna module is used to generate a fixed frequency single tone signal; The zero intermediate frequency receiver is used to receive a fixed frequency single tone signal generated by a wireless communication system and obtain basic parameters of the fixed frequency single tone signal; perform a first processing on the fixed frequency single tone signal to obtain a corresponding digital baseband single tone signal; The basic parameters of the fixed frequency single tone signal include frequency and duration; The zero intermediate frequency receiver is also used to perform a second processing on the digital baseband single-tone signal, obtain a received DC offset value of the digital baseband single-tone signal, and perform DC offset compensation on the digital baseband single-tone signal according to the received DC offset value to obtain a digital baseband single-tone signal after the received DC offset is compensated; The zero intermediate frequency receiver is also used to perform truncation processing on the digital baseband single tone signal after the compensation reception DC bias, and obtain the truncated digital baseband single tone signal; The zero intermediate frequency receiver is also used to obtain I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal according to the truncated digital baseband single-tone signal, and obtain an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency domain signals.

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