A method for obtaining IQ imbalance estimation values based on single-tone detection

Abstract

The present invention relates to a method for obtaining an IQ imbalance estimation value based on single-tone detection, including: a zero-IF receiver receives a fixed-frequency single-tone signal and obtains the basic parameters of the fixed-frequency single-tone signal; the fixed-frequency single-tone signal is subjected to a first process to obtain a corresponding digital baseband single-tone signal; the digital baseband single-tone signal is subjected to a second process to obtain a digital baseband single-tone signal after compensating for the received DC offset; the digital baseband single-tone signal after compensating for the received DC offset is subjected to a truncation process to obtain a truncated digital baseband single-tone signal; according to the truncated digital baseband single-tone signal, the I-channel and Q-channel frequency-domain signals of the truncated digital baseband single-tone signal are obtained, and the IQ phase imbalance estimation value and the IQ amplitude imbalance estimation value are obtained based on the I-channel and Q-channel frequency-domain signals. The method of the present 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 field of wireless communication technologies, 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 is simple in structure, high in integration, and low in power consumption compared with the superheterodyne receiver architecture. It has been widely used in communication systems such as mobile communication, wireless broadcast communication, and radar communication.

[0003] Although the zero-IF receiver has many advantages, due to the limitations of the radio frequency circuit structure, the zero-IF receiver also has some inherent defects. For example, poor isolation of radio frequency devices leads to local oscillator leakage, generating a received DC offset. The amplitude gains between the in-phase branch and the quadrature branch of the local oscillator signal are inconsistent, and the phase does not satisfy the quadrature relationship, resulting in IQ imbalance, etc., which will reduce the dynamic range of the receiver and seriously affect the system reception performance. Compared with the received DC offset, the IQ imbalance problem is more difficult to solve.

[0004] IQ imbalance suppression methods mainly include the following two aspects: First, optimizing the radio frequency circuit structure. This method starts from the root cause of the IQ imbalance problem and uses radio frequency devices with higher isolation and better consistency, but the circuit cost increases; Second, adopting digital IQ imbalance estimation and compensation technology. This method overcomes the inherent defects of the radio frequency circuit through digital signal processing, can effectively reduce the cost, 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] (I) Technical Problems to be Solved

[0007] In view of the above-mentioned disadvantages 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 in the IQ imbalance suppression method in the prior art.

[0008] (II) Technical Solutions

[0009] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0010] An embodiment of the present invention provides a method for obtaining an IQ imbalance estimation value based on single-tone detection, including:

[0011] S100. A zero-IF 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; the fixed-frequency single-tone signal is subjected to a first process to obtain a corresponding digital baseband single-tone signal;

[0012] The basic parameters of the fixed-frequency single-tone signal include frequency and duration;

[0013] S200. The zero-IF receiver performs a second process on the digital baseband single-tone signal, obtains the received DC bias value of the digital baseband single-tone signal, and performs DC bias compensation on the digital baseband single-tone signal according to the received DC bias value to obtain a digital baseband single-tone signal after compensating for the received DC bias;

[0014] S300. The zero-IF receiver performs a truncation process on the digital baseband single-tone signal after compensating for the received DC bias to obtain a truncated digital baseband single-tone signal;

[0015] S400. The zero-IF 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 an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency-domain signals.

[0016] Optionally, the method further includes:

[0017] S500. The zero-IF receiver performs IQ imbalance compensation and calibration on the inside according to the obtained IQ phase imbalance estimation value and IQ amplitude imbalance estimation value to obtain a calibrated zero-IF receiver to be measured.

[0018] Optionally, in S100, performing the first process on the fixed-frequency single-tone signal includes:

[0019] Performing down-conversion, analog low-pass filtering, and analog-to-digital conversion processes on the fixed-frequency single-tone signal to obtain a digital baseband single-tone signal corresponding to the fixed-frequency single-tone signal.

[0020] Optionally, S300 includes:

[0021] S310. Search for all zero-crossing positions and their indexes of the I-channel and Q-channel of the digital baseband single-tone signal after compensating for the received DC bias; sort the zero-crossing position indexes of the I-channel and Q-channel from small to large to obtain a sorted zero-crossing position index sequence of the I-channel and Q-channel;

[0022] S320. Perform a truncation process on the digital baseband single-tone signal after compensating for the received DC bias by using the sorted zero-crossing position index sequence of the I-channel and Q-channel to obtain a truncated digital baseband single-tone signal.

[0023] Optionally, S310 includes:

[0024] Search for the zero-crossing positions of the I-channel and Q-channel of the digital baseband single-tone signal after compensating for the received DC bias, and compare the digital baseband single-tone signals of the I-channel and Q-channel after compensating for the received DC bias with the adjacent amplitude in magnitude. If is greater than zero and is less than or equal to zero, or is less than zero and is greater than or equal to zero, then this position is the zero-crossing position, and obtain the index of this zero-crossing position.

[0025] Optionally, the S320 includes:

[0026] Substitute the digital baseband single-tone signal after compensating for the received DC bias into the following formula to obtain the truncated digital baseband single-tone signal:

[0027] ;

[0028] where is the truncated digital baseband single-tone signal, is the digital baseband single-tone signal after compensating for the received DC bias, Z0 is the starting position of the truncation window and is the smallest zero-crossing position index of the zero-crossing position of the I-channel, T A is the period of the digital baseband single-tone signal after compensating for the received DC bias, and 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-channel and Q-channel.

[0029] Optionally, the S400 includes:

[0030] 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:

[0031] ;

[0032] ;

[0033] where k is the frequency-domain index, k = 0, 1, 2,..., T A -1; is the I-channel of is the Q-channel of A is the period of the digital baseband single-tone signal after compensating for the received DC bias, F I (k) is the I-channel frequency-domain signal, F Q (k) is the Q-channel frequency-domain signal, j is the imaginary unit, and n is the time index.

[0034] Optionally, the S400 further includes:

[0035] S420. Obtain the frequency domain signals corresponding to the maximum modulus values in the I-channel and Q-channel frequency domain signals according to the I-channel and Q-channel frequency domain signals of the truncated digital baseband single-tone signal;

[0036] 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 the IQ amplitude imbalance estimation value:

[0037] ;

[0038] where, is the IQ amplitude imbalance estimation value, is the frequency domain signal corresponding to the maximum modulus value in the I-channel frequency domain signal, is the frequency domain signal corresponding to the maximum modulus value in the Q-channel frequency domain signal.

[0039] Optionally, the S400 further includes:

[0040] 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 the IQ phase imbalance estimation value:

[0041] ;

[0042] where, is the IQ phase imbalance estimation value, F I (k) is the I-channel frequency domain signal, F Q (k) is the Q-channel frequency domain signal, k max is the position index corresponding to the maximum modulus values of the I-channel and Q-channel frequency domain signals, and arg is to take the principal value of the complex argument.

[0043] In a second aspect, an embodiment of the present invention provides a wireless communication system, including:

[0044] An antenna module and a zero-IF receiver;

[0045] The antenna module is used to generate a fixed-frequency single-tone signal;

[0046] The zero-IF receiver is used to receive the fixed-frequency single-tone signal generated by the wireless communication system, and obtain the basic parameters of the fixed-frequency single-tone signal; perform a first process on the fixed-frequency single-tone signal to obtain a corresponding digital baseband single-tone signal;

[0047] The basic parameters of the fixed-frequency single-tone signal include frequency and duration;

[0048] The zero-IF receiver is also used to perform a second process on the digital baseband single-tone signal to obtain the received DC bias value of the digital baseband single-tone signal, and perform DC bias compensation on the digital baseband single-tone signal according to the received DC bias value to obtain the digital baseband single-tone signal after compensating the received DC bias;

[0049] The zero-IF receiver is also used to perform a truncation process on the digital baseband single-tone signal after compensating the received DC bias to obtain the truncated digital baseband single-tone signal;

[0050] The zero-IF receiver is also used to obtain 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 obtain the IQ phase imbalance estimation value and the IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency-domain signals.

[0051] (III) Beneficial effects

[0052] The beneficial effects of the present invention are as follows: A method for obtaining an IQ imbalance estimation value based on single-tone detection according to the present invention uses the characteristics of a single-tone signal to estimate IQ imbalance. By using the received DC bias estimation value of the digital baseband single-tone signal to compensate the received DC bias, the influence of the received DC bias on IQ imbalance estimation is reduced. By performing a truncation process on the digital baseband single-tone signal, spectrum leakage is suppressed. By calculating the I-channel and Q-channel frequency-domain signals of the digital baseband single-tone signal, the characteristics of the digital baseband single-tone signal are obtained, and the IQ amplitude imbalance estimation value and the IQ phase imbalance estimation value are calculated. Finally, simple, efficient and highly accurate IQ imbalance estimation is realized, which is convenient for accurate compensation and calibration of IQ imbalance, improves the receiving performance, and saves system costs. Description of the drawings

[0053] Figure 1 It is a schematic flowchart of a method for obtaining an IQ imbalance estimation value based on single-tone detection according to Embodiment 1 of the present invention;

[0054] Figure 2 It is a flowchart block diagram of the steps of a method for obtaining an IQ imbalance estimation value based on single-tone detection according to Embodiment 2 of the present invention;

[0055] Figure 3 It is Figure 2 A continuation diagram of the flowchart block diagram of the steps of a method for obtaining an IQ imbalance estimation value based on single-tone detection, that is, Process A;

[0056] Figure 4 It is Figure 3 A continuation diagram, which is Process B. Detailed implementation manners

[0057] For better explaining the present invention for easy understanding, the present invention will be described in detail below in conjunction with the accompanying drawings through specific embodiments.

[0058] A method for obtaining IQ imbalance estimation values based on single-tone detection proposed by an embodiment of the present invention aims to solve the technical problems of high circuit cost and low accuracy in IQ imbalance suppression methods in the prior art. The present invention utilizes the characteristics of single-tone signals for IQ imbalance estimation. By calculating the received DC bias estimation value of the digital baseband single-tone signal, compensating for the received DC bias, and reducing the influence of the received DC bias on IQ imbalance estimation. By performing truncation processing on the digital baseband single-tone signal, spectrum leakage is suppressed. By calculating the I-channel and Q-channel frequency-domain signals of the digital baseband single-tone signal, the characteristics of the digital baseband single-tone signal are obtained, and the IQ amplitude imbalance estimation value and the IQ phase imbalance estimation value are calculated. Finally, simple and efficient IQ imbalance estimation is realized, which is convenient for accurate compensation and calibration of IQ imbalance, improves the receiving performance, and saves system costs.

[0059] To better understand the above technical solution, the exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the 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 more clear and thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0060] See Figure 1 , a method for obtaining IQ imbalance estimation values based on single-tone detection according to an embodiment of the present invention includes:

[0061] Step S100: A zero-IF receiver receives a fixed-frequency single-tone signal generated by a wireless communication system and obtains the basic parameters of the fixed-frequency single-tone signal; the fixed-frequency single-tone signal is subjected to a first process to obtain a corresponding digital baseband single-tone signal;

[0062] The basic parameters of the fixed-frequency single-tone signal include frequency and duration;

[0063] Step S200: The zero-IF receiver performs a second process on the digital baseband single-tone signal to obtain the received DC bias value of the digital baseband single-tone signal, and performs DC bias compensation on the digital baseband single-tone signal according to the received DC bias value to obtain a digital baseband single-tone signal after compensating for the received DC bias;

[0064] Step S300: The zero-IF receiver performs truncation processing on the digital baseband single-tone signal after compensating for the received DC bias to obtain a truncated digital baseband single-tone signal;

[0065] Step S400: The zero-IF 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.

[0066] In step S200, calculating the received DC bias estimation value of the digital baseband single-tone signal and compensating the received DC bias of the digital baseband single-tone signal can solve the problem that the received DC bias generated by the local oscillator leakage in the zero-IF receiver affects the reception demodulation performance, thereby eliminating the influence of the DC bias on the IQ imbalance estimation.

[0067] In step S300, before calculating the I-channel and Q-channel frequency-domain signals of the digital baseband single-tone signal, the zero-IF receiver calculates the period of the digital baseband single-tone signal by using the zero-crossing detection method, and intercepts the digital baseband single-tone signal with a complete period by using the zero-crossing position, which can suppress the spectrum leakage generated by the Fourier transform.

[0068] In this embodiment, through the above method, simple and efficient IQ imbalance estimation can be achieved, thereby realizing accurate compensation and calibration of IQ imbalance, improving the reception performance of the zero-IF receiver, and saving system costs.

[0069] A method for obtaining an IQ imbalance estimation value based on single-tone detection according to an embodiment of the present invention includes:

[0070] Step S100: The zero-IF receiver receives a fixed-frequency single-tone signal generated by a wireless communication system and obtains the basic parameters of the fixed-frequency single-tone signal; the fixed-frequency single-tone signal is subjected to a first process to obtain a corresponding digital baseband single-tone signal;

[0071] The basic parameters of the fixed-frequency single-tone signal include frequency and duration;

[0072] Step S200: The zero-IF receiver performs a second process on the digital baseband single-tone signal to obtain the received DC bias value of the digital baseband single-tone signal, and performs DC bias compensation on the digital baseband single-tone signal according to the received DC bias value to obtain a digital baseband single-tone signal after compensating the received DC bias;

[0073] Step S300: The zero-IF receiver performs a truncation process on the digital baseband single-tone signal after compensating the received DC bias to obtain a truncated digital baseband single-tone signal;

[0074] Step S400: The zero-IF 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.

[0075] Specifically, the fixed-frequency single-tone signal is an ideal baseband complex single-tone signal with the same frequency and intersecting phases for the I-channel and Q-channel. Assuming the ideal baseband complex single-tone signal is x(t), then the fixed-frequency single-tone signal is also x(t), and x(t) can be expressed as:

[0076] ;

[0077] where f A is the frequency of the fixed-frequency single-tone signal, t A is the duration of the fixed-frequency single-tone signal, and j is the imaginary unit.

[0078] In this embodiment, the method further includes:

[0079] Step S500: The zero-IF receiver performs IQ imbalance compensation and calibration on the internal according to the obtained IQ phase imbalance estimation value and IQ amplitude imbalance estimation value, and obtains the calibrated zero-IF receiver to be measured.

[0080] In step S100, the first processing of the fixed-frequency single-tone signal includes:

[0081] The fixed-frequency single-tone signal is down-converted, analog low-pass filtered, and analog-to-digital converted to obtain the digital baseband single-tone signal corresponding to the fixed-frequency single-tone signal.

[0082] Assuming the digital baseband single-tone signal corresponding to the fixed-frequency single-tone signal is r(n), then r(n) can be expressed as:

[0083] ;

[0084] where n = 0, 1, 2,..., N - 1, N is the length of r(n), r I (n) is the I-channel of r(n), r Q (n) is the Q-channel of r(n), ε is the IQ amplitude imbalance value, θ is the IQ phase imbalance value, and the noise interference is ignored.

[0085] In this embodiment, in step S200, compensating the digital baseband single-tone signal for the received DC bias according to the received DC bias value to obtain the digital baseband single-tone signal after compensating the received DC bias includes:

[0086] Input the received DC bias value of the digital baseband single-tone signal into the following formula to obtain the digital baseband single-tone signal after compensating the received DC bias:

[0087] ;

[0088] Among them, 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, and l is the sliding window factor. is the digital baseband single-tone signal after compensating for the received DC bias;

[0089] The received DC bias value of the digital baseband single-tone signal is obtained by the sliding window averaging method.

[0090] Specifically, obtaining the received DC bias value of the digital baseband single-tone signal by the sliding window averaging method specifically includes:

[0091] Assume that the sliding window length is W = LS, where S is the sliding window step size and L is the sliding window factor, and L is an integer.

[0092] Before the first sliding of the sliding window, accumulate the amplitudes of the digital baseband single-tone signal r(n) within the sliding window. Taking the sliding window step size S as the calculation period, calculate the arithmetic mean of the accumulated amplitudes of the digital baseband single-tone signal period by period to obtain the received DC bias estimate value h( l ), which can be expressed as:

[0093] ;

[0094] 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.

[0095] When the number of accumulated amplitudes of the digital baseband signal is equal to the sliding window length W, start sliding the sliding window. Taking the sliding window step size S as the calculation period, calculate the arithmetic mean of the amplitudes of the digital baseband single-tone signal within the current sliding window length W period by period to obtain the received DC bias estimate value h( l ), which can be expressed as:

[0096] ;

[0097] ;

[0098] Among them, is rounding down.

[0099] By the above method, the received DC bias in the digital baseband single-tone signal is accurately measured and stepped, thereby eliminating or significantly reducing the influence of this 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.

[0100] In the specific implementation process, step S300 includes:

[0101] Step S310: Search for all zero-crossing positions and their indices of the I-channel and Q-channel of the digital baseband single-tone signal after compensating for the received DC bias; sort the zero-crossing position indices of the I-channel and Q-channel from small to large to obtain the sorted zero-crossing position index sequences of the I-channel and Q-channel.

[0102] Step S320: Truncate the digital baseband single-tone signal after compensating for the received DC bias using the sorted zero-crossing position index sequences of the I-channel and Q-channel to obtain the truncated digital baseband single-tone signal.

[0103] Step S310 includes:

[0104] Search for the zero-crossing positions of the I-channel and Q-channel of the digital baseband single-tone signal after compensating for the received DC bias, and compare the digital baseband single-tone signals of the I-channel and Q-channel after compensating for the received DC bias with the adjacent amplitudes If is greater than zero and is less than or equal to zero, or is less than zero and is greater than or equal to zero, then this position is the zero-crossing position, and obtain the index of this zero-crossing position.

[0105] Step S320 includes:

[0106] Substitute the digital baseband single-tone signal after compensating for the received DC bias into the following formula to obtain the truncated digital baseband single-tone signal:

[0107] ;

[0108] where is the truncated digital baseband single-tone signal, is the digital baseband single-tone signal after compensating for the received DC bias, Z0 is the starting position of the truncation window, which is the smallest zero-crossing position index of the zero-crossing position of the I-channel, and T A is the period of the digital baseband single-tone signal after compensating for the received DC bias, and is twice as large as the average value of the zero-crossing position index differences obtained by performing differential calculations and arithmetic averaging on the zero-crossing position index sequences of the I-channel and Q-channel.

[0109] Furthermore, the specific steps to obtain the period T A of the digital baseband single-tone signal after compensating for the received DC bias are:

[0110] Perform differential calculations on the sorted zero-crossing position index sequences of the I-channel and Q-channel respectively to obtain the zero-crossing position index difference sequences, which can be expressed as:

[0111] ;

[0112] ;

[0113] Among them, is the differential sequence of the zero-crossing position index of the I path, and z I (m) is the zero-crossing position index sequence of the I path, is the differential sequence of the zero-crossing position index of the Q path, and z Q (m) is the zero-crossing position index sequence of the Q path, and m is an index variable used to represent each element in the sequence.

[0114] Immediately afterwards, calculate the arithmetic mean of the zero-crossing position index differential sequence to obtain the average value of the zero-crossing position index difference, which can be expressed as:

[0115] ;

[0116] Then the period T of the digital baseband single-tone signal after compensating for the received DC bias A can be expressed as:

[0117] ;

[0118] In this embodiment, step S400 includes:

[0119] Step 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:

[0120] ;

[0121] ;

[0122] Among them, k is the frequency-domain index, k = 0, 1, 2,..., T A -1; is the I-channel of , is the Q-channel of , and T A is the period of the digital baseband single-tone signal after compensating for the received DC bias, and F I (k) is the I-channel frequency-domain signal, and F Q (k) is the Q-channel frequency-domain signal, j is the imaginary unit, and n is the time index.

[0123] Step S420: Obtain the frequency-domain signals corresponding to the maximum modulus values in the I-channel and Q-channel frequency-domain signals according to the I-channel and Q-channel frequency-domain signals of the truncated digital baseband single-tone signal;

[0124] In the specific implementation process, search for the maximum modulus values of the I-channel and Q-channel frequency-domain signals and , and wait until the position index k of the maximum modulus value max , then and can be expressed as:

[0125] ;

[0126] ;

[0127] 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 the IQ amplitude imbalance estimation value:

[0128] ;

[0129] where, is the IQ amplitude imbalance estimation value, is the frequency-domain signal corresponding to the maximum modulus value in the I-channel frequency-domain signal, is the frequency-domain signal corresponding to the maximum modulus value in the Q-channel frequency-domain signal.

[0130] 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 the IQ phase imbalance estimation value:

[0131] ;

[0132] where, is the IQ phase imbalance estimation value, F I (k) is the I-channel frequency-domain signal, F Q (k) is the Q-channel frequency-domain signal, k max is the position index corresponding to the maximum modulus values of the I-channel and Q-channel frequency-domain signals, and arg is the principal value of the complex argument.

[0133] A method for obtaining an IQ imbalance estimation value based on single-tone detection in this embodiment acts on the demodulation output signal of the entire wireless communication system and is applicable to various application scenarios for internal IQ imbalance compensation and calibration in zero-IF receivers.

[0134] Furthermore, the wireless communication system to which the method of the present invention is applied can be a mobile communication terminal device, an Internet of Things node, a satellite communication system, etc.

[0135] A method for obtaining an IQ imbalance estimation value based on single-tone detection in this embodiment can be calibrated once before the zero-IF receiver is put into use. That is, during the production process of the zero-IF receiver, the manufacturer can perform a comprehensive IQ imbalance calibration before leaving the factory. This is usually carried out using a standard signal source in a controlled environment to ensure that each device has the highest possible performance when leaving the production line.

[0136] In addition, when the zero-IF 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 the characteristics of the zero-IF receiver may be affected by environmental factors (such as temperature, humidity, etc.), resulting in deviation from the factory settings.

[0137] After the zero-IF receiver is put into use, a method for obtaining the IQ imbalance estimation value based on single-tone detection of the present invention can also be used, which is carried out during the communication idle period or a specific maintenance window period to maintain the best performance of the system. For some application scenarios with high performance requirements, such as military communication or precision scientific instruments, the zero-IF receiver continuously monitors the IQ imbalance and dynamically adjusts the compensation parameters according to the real-time measurement results. This method can cope with the drift problems caused by environmental changes or long-term use, ensuring long-term stable operation.

[0138] In the actual application process, if the working environment where the zero-IF receiver is located is relatively stable and the requirements for IQ imbalance are not extremely harsh, then only one-time calibration is required in the initial stage. For those systems with large changes in working conditions and requiring high precision for a long time, the method of continuous monitoring and adjustment is more suitable to ensure that the optimal IQ balance state is always maintained.

[0139] The present invention uses the characteristics of the single-tone signal to estimate the IQ imbalance. By calculating the received DC bias estimation value of the digital baseband single-tone signal, compensating the received DC bias, reducing the influence of the received DC bias on the IQ imbalance estimation, by performing truncation processing on the digital baseband single-tone signal to suppress spectral leakage, by calculating the I-channel and Q-channel frequency-domain signals of the digital baseband single-tone signal, obtaining the characteristics of the digital baseband single-tone signal, calculating the IQ amplitude imbalance estimation value and the IQ phase imbalance estimation value, finally realizing simple and efficient IQ imbalance estimation, facilitating accurate compensation and calibration of IQ imbalance, improving the receiving performance, and saving system costs.

[0140] A method for obtaining the IQ imbalance estimation value based on single-tone detection in this embodiment is applied to the wireless physical layer of the dual-mode communication protocol in the power user electricity consumption information acquisition system. The system architecture used refers to the wireless physical layer part of the "Dual-Mode Communication Interconnection and Interworking Technical Specification Part 4-1: Physical Layer Communication Protocol" released by the State Grid. The communication frequency point used by the system radio frequency antenna is f c = 471 MHz, the number of bits of the analog-to-digital converter of the zero-IF receiver is 12 bits, the sampling rate is F S = 2.083 MHz, the frequency of the fixed-frequency single-tone signal is f A = 8 kHz, the length of the fixed-frequency single-tone signal is N = 10000, and the frequency and length of the fixed-frequency single-tone signal satisfy 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 received DC bias h(0) = 0.

[0141] See Figure 2 、 Figure 3 and Figure 4 , the specific steps of the method are as follows:

[0142] (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 processing, the received digital baseband single-tone signal r(n) is sampled.

[0143] (2) Using the sliding window averaging method, with the sliding window step size S as the calculation and compensation period of the received DC bias, the amplitudes of r(n) within the sliding window are accumulated, and the arithmetic mean of the accumulated amplitudes of r(n) is calculated for each period to obtain the estimated value h( l ) of the received DC bias. The received DC bias of r(n) is compensated for each period using h( l ), and the digital baseband signal after receiving DC bias compensation is obtained .

[0144] (3) Using the zero-crossing detection method, compare 's I-channel adjacent amplitudes and , as well as 's Q-channel adjacent amplitudes and to complete and zero-crossing position search and sorting to obtain the I-channel zero-crossing position index sequence z I (m) and the Q-channel zero-crossing position index sequence z Q (m). Differencing calculations are performed on z I (m) and z Q (m) respectively to obtain the zero-crossing position index difference sequence and . Calculate the arithmetic mean of and to obtain the average value of the zero-crossing position index difference, and further obtain the period T A of the digital baseband single-tone signal. The A is truncated with a truncation window of length T , and the starting position of the truncation window is the first index Z0 of z I (m), and the truncated digital baseband single-tone signal is obtained .

[0145] (4) Calculate through FFT I-channel and Q-channel frequency-domain signals F I (k) and F Q (k), search for F I (k) and F Q (k) modulus maximum value and , obtain the position index k of the modulus maximum value max . Calculate and ratio, obtain the IQ amplitude imbalance estimation value . Calculate F I (k) and F Q (k) at k = k max phase difference at this point, obtain the IQ phase imbalance estimation value .

[0146] Through the above method, it is possible to improve the accuracy and reliability of IQ imbalance estimation on the basis of meeting the requirements of low power consumption and low latency, and effectively save the cost of the zero-IF receiver.

[0147] Furthermore, the embodiment of the present invention further includes a wireless communication system, including:

[0148] Antenna module, zero-IF receiver;

[0149] The antenna module is used to generate a fixed-frequency single-tone signal;

[0150] The zero-IF receiver is used to receive the fixed-frequency single-tone signal generated by the wireless communication system and obtain the basic parameters of the fixed-frequency single-tone signal; perform a first processing on the fixed-frequency single-tone signal to obtain the corresponding digital baseband single-tone signal;

[0151] The basic parameters of the fixed-frequency single-tone signal include frequency and duration;

[0152] The zero-IF receiver is further used to perform a second processing on the digital baseband single-tone signal to obtain the 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 the digital baseband single-tone signal after compensating the received DC offset;

[0153] The zero-IF receiver is further used to perform a truncation process on the digital baseband single-tone signal after compensating the received DC offset to obtain the truncated digital baseband single-tone signal;

[0154] The zero-IF receiver is also used to obtain 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 obtain the IQ phase imbalance estimation value and the IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency-domain signals.

[0155] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more unless otherwise specifically defined.

[0156] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "connected to", "fixed" and other terms should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium; it may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0157] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0158] 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 connection 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, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0159] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to 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 including: S100. A zero-IF 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; S200. The zero-IF receiver performs a second processing on the digital baseband single-tone signal to obtain a received 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 received DC offset value to obtain a digital baseband single-tone signal after compensating the received DC offset; S300. The zero-IF receiver performs a truncation processing on the digital baseband single-tone signal after compensating the received DC offset to obtain a truncated digital baseband single-tone signal; S400. The zero-IF receiver obtains 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 an IQ phase imbalance estimation value and an IQ amplitude imbalance estimation value according to the I-channel and Q-channel frequency-domain signals.

2. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 1, wherein The method further includes: S500. The zero-IF receiver performs IQ imbalance compensation and calibration on the inside according to the obtained IQ phase imbalance estimation value and IQ amplitude imbalance estimation value to obtain a calibrated zero-IF receiver to be measured.

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

4. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 1, wherein The S300 includes: S310. Search for all zero-crossing positions and their indexes of the I-channel and Q-channel of the digital baseband single-tone signal after compensating the received DC offset; sort the zero-crossing position indexes of the I-channel and Q-channel from small to large to obtain a sorted zero-crossing position index sequence of the I-channel and Q-channel; S320. Perform a truncation processing on the digital baseband single-tone signal after compensating the received DC offset by using the sorted zero-crossing position index sequence of the I-channel and Q-channel to obtain a truncated digital baseband single-tone signal.

5. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 4, characterized in that, The S310 includes: Search for the zero-crossing positions of the I-channel and Q-channel of the digital baseband single-tone signal after receiving DC bias compensation, and compare the digital baseband single-tone signals of the I-channel and Q-channel after receiving DC bias compensation with the adjacent amplitudes in magnitude. If is greater than zero and is less than or equal to zero, or is less than zero and is greater than or equal to zero, then this position is the zero-crossing position, and obtain the index of this zero-crossing position.

6. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 4, wherein The S320 includes: substitute the digital baseband single-tone signal after compensating the received DC offset into the following formula to obtain a truncated digital baseband single-tone signal: ； Among them, is the truncated digital baseband single-tone signal, is the digital baseband single-tone signal after compensating for the received DC bias. Z0 is the starting position of the truncation window and the minimum zero-crossing position index of the zero-crossing position of the I channel. T A is the period of the digital baseband single-tone signal after compensating for the received DC bias, and is twice as large as the average value of the zero-crossing position index differences obtained by performing differential calculations and arithmetic averaging on the zero-crossing position index sequences of the I and Q channels.

7. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 1, wherein The S400 includes: S410. Input the truncated digital baseband single-tone signal into the following formula to obtain 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; is the I-channel of ; is the Q-channel of ; is the truncated digital baseband single-tone signal, T A is the period of the digital baseband single-tone signal after compensating for the received DC bias, F I (k) is the I-channel frequency-domain signal, F Q (k) is the Q-channel frequency-domain signal, j is the imaginary unit, and n is the time index.

8. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 7, wherein The S400 further includes: S420. According to the I-channel and Q-channel frequency-domain signals of the truncated digital baseband single-tone signal, obtain the frequency-domain signals corresponding to the maximum modulus values in the I-channel and Q-channel frequency-domain signals respectively; 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: ； Wherein, is the IQ amplitude imbalance estimation value, is the frequency domain signal corresponding to the maximum modulus value in the I-channel frequency domain signal, is the frequency domain signal corresponding to the maximum modulus value in the Q-channel frequency domain signal.

9. The method for obtaining the IQ imbalance estimation value based on single-tone detection according to claim 8, characterized in that, The S400 further includes: 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: ； Among them, is the IQ phase imbalance estimation value, F I (k) is the I-channel frequency-domain signal, F Q (k) is the Q-channel frequency-domain signal, k max is the position index corresponding to the maximum modulus value of the I-channel and Q-channel frequency-domain signals, and arg is the principal value of the complex argument.

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

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