An Adaptive Receiving Array Intermodulation Interference Cancellation Method and Device

Abstract

The present invention relates to a method and apparatus for self - adaptive receive array inter - modulation interference cancellation. The method includes: collecting data from all downlink channels and collecting data from the uplink channels where interference cancellation is required; using the downlink signal and power amplifier inter - modulation model to construct a fitting inter - modulation signal, and performing uplink shaping filtering on it to obtain a fitting inter - modulation signal that only contains the uplink passband part; performing cross - correlation operation on the filtered fitting inter - modulation signal and the actual uplink interference signal, comparing the cross - correlation operation result with a preset threshold, and recording the set of all downlink channels that will interfere with the uplink reception as B according to the comparison result; using an optimization algorithm to estimate the downlink channel set B and the cancellation coefficient of the uplink interference, then combining the cancellation coefficient with the downlink signal to generate a cancellation signal with the same magnitude and opposite phase as the uplink interference, and finally adding or subtracting the generated cancellation signal from the uplink signal to eliminate the interference falling within the uplink band.

Description

Technical Field

[0001] The present invention relates to the technical field of antenna array transceiver interference cancellation, and more particularly, to an adaptive receive array intermodulation interference cancellation method and apparatus. Background Art

[0002] In a transceiver coplanar antenna array, when the antenna operates in the FDD mode, the transmitted signal generates non-linear spectra due to the non-linear characteristics of the transmitting channel. These spectra usually fall into the receiving frequency band, and even after the isolation of the transceiver antennas and the suppression of the out-of-band filter of the transmitter, a part of the energy still remains, thus affecting the signal-to-noise ratio of the receiving link.

[0003] Usually, the energy outside the transmitting band is suppressed by a filter after the last-stage amplifier of the transmitter. However, increasing the out-of-band suppression of the filter will lead to a decrease in the in-band gain of the transmitter and an increase in the volume and weight of the filter, thus affecting the efficiency, power consumption, volume and weight of the transmitting link.

[0004] In order not to affect the efficiency, power consumption and volume of the transmitting link, the present invention provides a method that does not require overly strict requirements for the transmitting filter, only needs a smaller sampling rate to achieve the purpose, reduces the algorithm resource pressure, and cancels the interference of the received signal. Summary of the Invention

[0005] The present invention aims to overcome at least one defect (insufficiency) of the above-mentioned prior art, and provides an adaptive receive array intermodulation interference cancellation method and apparatus, which effectively solves the out-of-band interference of the transmission to the reception in the antenna array, greatly reduces the requirement for the out-of-band suppression of the filter by the transmitting channel, reduces the power consumption, volume, weight of the array, and reduces the algorithm resource pressure, and improves the efficiency of the array.

[0006] In a first aspect, the technical solution adopted by the present invention is an adaptive receive array intermodulation interference cancellation method, and the method includes:

[0007] S1: Collect data from all downlink channels and collect data from the uplink channels that need interference cancellation;

[0008] S2: Use the downlink signal and the power amplifier intermodulation model to construct a fitting intermodulation signal, and perform uplink shaping filtering on it to obtain a fitting intermodulation signal that only contains the uplink passband part;

[0009] S3: Perform a cross-correlation operation on the filtered fitting intermodulation signal in step S2 and the uplink actual interference signal, and compare the cross-correlation operation result with a preset threshold. If the cross-correlation result is greater than the threshold, it means that the intermodulation of this downlink channel affects the uplink reception, and then record the set of all downlink channels that will interfere with the uplink reception as B;

[0010] S4: Use an optimization algorithm to estimate the downlink channel set B and the cancellation coefficient of the uplink interference. Construct an anti-interference model using the cancellation coefficient. In the anti-interference model, combine the cancellation coefficient with the downlink signal to obtain a cancellation signal that is equal in magnitude and opposite in phase to the uplink interference. Add or subtract the generated cancellation signal from the uplink signal to affect the phase, thereby eliminating the interference falling within the uplink band.

[0011] In this application, digital interference cancellation is adopted. The optimal cancellation coefficient is calculated using an optimization algorithm to generate a signal that is opposite to the intermodulation of the downlink signal. It can effectively remove the interference of the nonlinearity in the uplink receiving band on the receiving array, improve the quality of the uplink signal, improve the signal-to-noise ratio, reduce the bit error rate, and improve the reliability and data transmission rate of the communication system. Such technical effects are particularly important for communication systems operating in complex environments (such as high interference, multi-band sharing, etc.), which helps to improve the spectral efficiency and overall performance of the system. Moreover, since the solution of the present invention only needs to focus on the part of the intermodulation interference falling within the uplink passband, rather than canceling the intermodulation of all frequency bands, and it processes the signal at the receiver without any impact on the downlink chain. In this way, only a smaller sampling rate is required to achieve the purpose of removing the interference of the nonlinearity in the uplink receiving band on the receiving array, greatly reducing the algorithm resource pressure.

[0012] Preferably, in the step S2, the power amplifier intermodulation model is the Saleh model or the Rapp model or the Volterra series model or other models. In this application, the selection of the power amplifier intermodulation model can be made according to the working environment and performance requirements of the power amplifier to achieve the optimal fitting intermodulation signal.

[0013] More preferably, the Volterra series model is selected as the power amplifier intermodulation model, and the actually used power amplifier intermodulation model is obtained for the component of the signal falling within the uplink passband. The formula is:

[0014] Y’(k) = y(k)G(t)

[0015] where y(k) is the output of the Volterra series model; G(t) is the output of the uplink shaping filter; Y’(k) represents the output of the power amplifier intermodulation model, which is the fitting intermodulation signal only containing the uplink passband part.

[0016] The Volterra series model selected in this application can handle the high-order nonlinear effects of the power amplifier. Especially when the input signal is strong, the power amplifier exhibits significant nonlinear behavior, and it has good flexibility and wide applicability. It can be used to describe various types of nonlinear systems, including various operating modes of the power amplifier. In addition, it can also handle the intermodulation distortion of multi-frequency components. By adjusting the order of the Volterra model (i.e., the order of the polynomial terms included), it is possible to trade off between different accuracies and computational efficiencies, and improve the accuracy of the constructed fitting intermodulation signal.

[0017] Preferably, in step S2, a band-limiting operation is further included for the power amplifier intermodulation model to align the frequency points of the power amplifier intermodulation model and the uplink shaping filter.

[0018] Since the power amplifier model is centered on the downlink signal frequency point, and the uplink shaping filter is centered on the uplink signal frequency point, it is necessary to align the frequency points of the two to avoid spectral misalignment between the power amplifier and the filter, ensure the phase and frequency consistency of the signal during transmission, ensure that the power amplifier and the filter can work within the correct frequency bandwidth range, improve the signal quality, reduce the error caused by inaccurate frequency alignment, and make the constructed fitting intermodulation signal more accurate.

[0019] Preferably, in step S3, the cross-correlation operation formula is:

[0020]

[0021] where x * (k - t) represents the uplink signal; Y′(k) represents the output of the power amplifier intermodulation model; r yx (t) represents the cross-correlation result.

[0022] Comparing the cross-correlation result calculated using the above formula with a preset threshold can quickly find the downlink channels where the intermodulation has an impact on the uplink reception. Among them, the threshold is set according to empirical values. When the cross-correlation result is greater than the preset threshold, it means that the intermodulation of this downlink channel has an impact on the uplink reception, and it is necessary to find out these downlink channels that will interfere with the uplink reception and perform the operations of subsequent steps to eliminate the interference falling within the uplink band.

[0023] Preferably, in step S4, it includes:

[0024] S41: Subtract the output Y′(k) of the power amplifier intermodulation model from the actual uplink interference signal x(k) to obtain the error e(k) of the anti-interference model, and obtain several cancellation coefficient groups based on the error;

[0025] S42: Select the n cancellation coefficient groups with the best cancellation effect from several cancellation coefficient groups to form a new initial set, denoted as the initial set C = [H1 H2 H3 … H n ;

[0026] S43: Optimize the cancellation coefficients in the initial set C until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

[0027] Through the above method, the downlink channel set B and the cancellation coefficients of the uplink interference are obtained, so that a cancellation signal with the same magnitude and opposite phase as the uplink interference can be generated by combining it with the downlink signal, and the generated cancellation signal is added or subtracted from the uplink signal to affect the phase, thereby effectively eliminating the interference falling within the uplink band.

[0028] Preferably, in the step S41, the obtaining of several cancellation coefficients according to the error includes:

[0029] S411: Use an optimization algorithm to find a suitable cancellation coefficient h such that

[0030]

[0031] S412: Since the overdetermined equation has no unique solution, the least squares method is used to solve the approximate solution of the optimal cancellation coefficient, and several cancellation coefficient groups H are obtained. The formula is:

[0032] H = (UU * ) -1 U * X

[0033] where U represents the downlink transmission signal; X represents the uplink received signal.

[0034] Through the above method, the problem that the overdetermined equation has no unique solution can be effectively solved, so that the error between the obtained cancellation coefficients and the actual optimal cancellation coefficients is minimized, and the anti-interference performance of the system is improved.

[0035] Preferably, in the step S43, the optimization process includes:

[0036] S431: Select the two groups of cancellation coefficients with the best cancellation effect from the initial set C, then randomly exchange a coefficients among them, and calculate the cancellation error of the two new groups of cancellation coefficients. If the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst performing group in the initial set C by more than 1 dB, add the newly generated group of cancellation coefficients to the initial set C to form a new set C1;

[0037] S432: Randomly select two sets of cancellation coefficients from set C1, randomly exchange a coefficients among them, calculate the cancellation error of the two new sets of cancellation coefficients. If the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, add the newly generated set of cancellation coefficients to set C1 to form a new set C2;

[0038] S433: Randomly select a set of cancellation coefficients from set C2, and then randomly select cancellation coefficients from this set of coefficients, where m is the number of cancellation coefficients in this set, denotes rounding up; then change the amplitude A of the selected cancellation coefficients to a random value in the range [0.95A, 1.05A] until the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, and then add the newly generated set of cancellation coefficients to the initial set C to form a new set C3;

[0039] S434: Determine the number of sets of cancellation coefficients in set C3. If it is greater than 4m, delete several sets of the worst-performing cancellation coefficients until the number of elements in the set is less than or equal to 4m;

[0040] S435: Repeat steps S431 - S434 until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

[0041] By implementing the above steps to continuously optimize the cancellation coefficients, it can be ensured that the obtained cancellation coefficients can cancel the interference signal below the noise floor, thereby effectively removing the interference of the in-band nonlinearity of the uplink reception to the receiving array.

[0042] On the other hand, the present invention also provides an adaptive receiving array intermodulation interference cancellation device, which at least includes a plurality of uplink channels, a plurality of downlink channels, and an interference estimation module;

[0043] Among them, the interference estimation module includes:

[0044] A data acquisition unit for acquiring data from all downlink channels and acquiring data from the uplink channels that need interference cancellation;

[0045] An intermodulation signal processing unit for constructing a fitting intermodulation signal using the downlink signal and the power amplifier intermodulation model and performing uplink shaping filtering on it to obtain a fitting intermodulation signal that only contains the uplink passband part;

[0046] The cross-correlation operation unit is used to perform a cross-correlation operation on the fitted intermodulation signal obtained after being processed by the intermodulation signal processing unit and the actual uplink interference signal, and compare the cross-correlation operation result with a preset threshold. If the cross-correlation result is greater than the threshold, it indicates that the intermodulation of the downlink channel affects the uplink reception. Then, the set of all downlink channels that interfere with the uplink reception is recorded as B;

[0047] The interference cancellation unit is used to estimate the cancellation coefficients of the downlink channel set B and the uplink interference using an optimization algorithm, construct an anti-interference model using the cancellation coefficients, combine the cancellation coefficients with the downlink signal in the anti-interference model to generate a cancellation signal with the same magnitude and opposite phase as the uplink interference, and add or subtract the generated cancellation signal from the uplink signal to affect the phase, thereby eliminating the interference falling within the uplink band.

[0048] Preferably, in the interference cancellation unit, it further includes:

[0049] The cancellation coefficient acquisition component is used to obtain the error e(k) of the anti-interference model by subtracting the output Y′(k) of the power amplifier intermodulation model from the actual uplink interference signal x(k), and obtain several groups of cancellation coefficients according to the error;

[0050] The cancellation coefficient selection component is used to select the n groups of cancellation coefficients with the best cancellation effect from several groups of cancellation coefficients to form a new initial set, denoted as the initial set C = [H1H2H3…H n ;

[0051] The cancellation coefficient optimization component is used to optimize the cancellation coefficients in the initial set C until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

[0052] Compared with the prior art, the beneficial effects of the present invention are:

[0053] The present invention adopts the method of digital interference cancellation, uses an optimization algorithm to find the cancellation coefficients with the best interference cancellation effect for reception. When the antenna is working, a signal with a phase opposite to the intermodulation of the downlink signal falling within the uplink band is generated to cancel the influence of the downlink intermodulation on the uplink reception. In addition, since this solution only needs to focus on the part of the intermodulation interference falling within the uplink passband and does not need to cancel the intermodulation of all frequency bands, only a smaller sampling rate is required to achieve the purpose, reducing the algorithm resource pressure. At the same time, the algorithm used in the present invention is based on correlation and optimization algorithm, and will not generate components of non-interference signals and will not affect the original uplink signal. Therefore, this patent effectively solves the out-of-band interference of the transmission to the reception in the antenna array, greatly reducing the requirement for out-of-band suppression of the filter by the transmission channel, reducing the power consumption, volume, and weight of the entire array, and improving the efficiency of the entire array. Description of the Drawings

[0054] Figure 1 Schematic diagram of the method flow provided by this embodiment.

[0055] Figure 2 Schematic diagram of the device structure provided by this embodiment. Detailed implementation manners

[0056] The attached drawings of the present invention are only for illustrative purposes and should not be construed as limitations on the present invention. To better illustrate the following embodiments, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0057] Embodiment 1

[0058] As Figure 1 shown, this embodiment provides an adaptive receiving array intermodulation interference cancellation method, and the method includes:

[0059] S1: Collect data from all downlink channels and collect data from the uplink channels that need interference cancellation;

[0060] S2: Use the downlink signal and power amplifier intermodulation model to construct a fitting intermodulation signal, and perform uplink shaping filtering on it to obtain a fitting intermodulation signal that only contains the uplink passband part;

[0061] S3: Perform cross-correlation operation on the filtered fitting intermodulation signal in step S2 and the uplink actual interference signal, and compare the cross-correlation operation result with a preset threshold. If the cross-correlation result is greater than the threshold, it means that the intermodulation of this downlink channel affects the uplink reception. Then, record the set of all downlink channels that will interfere with the uplink reception as B;

[0062] S4: Use an optimization algorithm to estimate the cancellation coefficients of the downlink channel set B and the uplink interference, construct an anti-interference model using the cancellation coefficients, combine the cancellation coefficients with the downlink signal in the anti-interference model to obtain a cancellation signal with the same magnitude and opposite phase as the uplink interference, and add or subtract the generated cancellation signal from the uplink signal to affect the phase, so as to eliminate the interference falling within the uplink band.

[0063] In this application, a digital interference cancellation method is adopted to calculate the optimal cancellation coefficient using an optimization algorithm, generating a signal opposite to the intermodulation of the downlink signal. This can effectively remove the interference of the in-band non-linearity of the uplink reception on the receiving array, improve the quality of the uplink signal, enhance the signal-to-noise ratio, reduce the bit error rate, and improve the reliability and data transmission rate of the communication system. Such technical effects are particularly important for communication systems operating in complex environments (such as high interference, multi-band sharing, etc.), helping to improve the spectral efficiency and overall performance of the system. Moreover, since the solution of the present invention only needs to focus on the part of the intermodulation interference falling within the uplink passband, rather than canceling the intermodulation of all frequency bands, and it processes the signal at the receiver without any impact on the downlink chain, only a smaller sampling rate is required to achieve the purpose of removing the interference of the in-band non-linearity of the uplink reception on the receiving array, greatly reducing the algorithm resource pressure.

[0064] Preferably, in the step S2, the power amplifier intermodulation model is the Saleh model or the Rapp model or the Volterra series model or other models. In this application, the selection of the power amplifier intermodulation model can be made according to the working environment and performance requirements of the power amplifier to achieve the optimal fitting intermodulation signal.

[0065] More preferably, in this embodiment, the Volterra series model is selected as the power amplifier intermodulation model, and its expression is as follows:

[0066] y(k) = y0 + ∑h1(m)u(k - m) + ∑h2(m1,m2)u(k - m1)u(k - m2) + …

[0067] where u(k) is the downlink signal, y(k) is the output of the Volterra series model, and h is the coefficient corresponding to the model;

[0068] In addition, this solution only focuses on the components of the signal falling within the uplink passband. Therefore, the formula of the actually used power amplifier intermodulation model is:

[0069] Y′(k) = y(k)G(t) where y(k) is the output of the Volterra series model; G(t) is the output of the uplink shaping filter; Y′(k) represents the output of the power amplifier intermodulation model, which is a fitting intermodulation signal only containing the uplink passband part.

[0070] The Volterra series model selected in this application can handle the high-order nonlinear effects of power amplifiers. Especially when the input signal is strong, the power amplifier exhibits significant nonlinear behavior, and it has good flexibility and wide applicability. It can be used to describe various types of nonlinear systems, including various operating modes of power amplifiers. In addition, it can also handle the intermodulation distortion of multi-frequency components. By adjusting the order of the Volterra model (i.e., the order of the polynomial terms included), a trade-off can be achieved between different accuracies and computational efficiencies, improving the accuracy of the constructed fitting intermodulation signal.

[0071] Preferably, in the step S2, a band-limiting operation is further included on the power amplifier intermodulation model to align the frequency points of the power amplifier intermodulation model and the uplink shaping filter.

[0072] Since the power amplifier model is centered on the downlink signal frequency point, and the uplink shaping filter is centered on the uplink signal frequency point, it is necessary to align the frequency points of the two to avoid spectral misalignment between the power amplifier and the filter, ensure the phase and frequency consistency of the signal during transmission, ensure that the power amplifier and the filter can work within the correct frequency bandwidth range, improve the signal quality, reduce the errors caused by inaccurate frequency alignment, and make the constructed fitting intermodulation signal more accurate.

[0073] Preferably, in the step S3, the cross-correlation operation formula is:

[0074]

[0075] where, x * (k - t) represents the uplink signal; Y′(k) represents the output of the power amplifier intermodulation model; r yx (t) represents the cross-correlation result.

[0076] Comparing the cross-correlation result calculated using the above formula with a preset threshold, the downlink channels where intermodulation affects the uplink reception can be quickly found. Among them, the threshold is set according to empirical values. When the cross-correlation result is greater than the preset threshold, it indicates that the intermodulation of this downlink channel affects the uplink reception. It is necessary to find out these downlink channels that interfere with the uplink reception and perform the operations of subsequent steps to eliminate the interference falling within the uplink band.

[0077] Preferably, in the step S4, it includes:

[0078] S41: Using the actual uplink interference signal x(k) minus the output Y′(k) of the power amplifier intermodulation model to obtain the error e(k) of the anti-interference model, and obtaining several groups of cancellation coefficients according to the error;

[0079] Specifically, in the step S41, the calculation formula for the error is:

[0080] e(k) = x(k) - Y′(k)

[0081] Then use the optimization algorithm to find the appropriate cancellation coefficient h such that:

[0082]

[0083] Since the overdetermined equation has no unique solution, the least squares method is used to solve the approximate solution of the optimal cancellation coefficient, and several cancellation coefficient groups H are obtained. The formula is:

[0084] H = (UU * ) -1 U * X

[0085] where U represents the downlink transmission signal; X represents the uplink received signal.

[0086] Through the above method, a series of cancellation coefficients can be obtained. If these cancellation coefficients at this time cannot cancel the interference signal below the noise floor, the following operations are still required to optimize the above cancellation coefficients, so that the error between the obtained cancellation coefficients and the actual optimal cancellation coefficients is minimized, and the anti-interference performance of the system is improved.

[0087] S42: Select the n cancellation coefficient groups with the best cancellation effect from several cancellation coefficient groups to form a new initial set, denoted as the initial set C = [H1 H2 H3 … H n ;

[0088] S43: Optimize the cancellation coefficients in the initial set C until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

[0089] Specifically, in the step S43, the optimization process includes:

[0090] Step S431: First, select the two groups of cancellation coefficients with the best cancellation effect from the initial set C, then randomly exchange a of their coefficients, and calculate the cancellation error of the two new cancellation coefficient groups. If the cancellation error of the new cancellation coefficient groups is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, then add the newly generated cancellation coefficient groups to the initial set C to form a new set C1;

[0091] Step S432: Randomly select two groups of cancellation coefficients from the set C1, and randomly exchange a of their coefficients, calculate the cancellation error of the two new cancellation coefficient groups. If the cancellation error of the new cancellation coefficient groups is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, then add the newly generated cancellation coefficient groups to the set C1 to form a new set C2;

[0092] Step S433: Randomly select a set of cancellation coefficients from set C2, and then randomly select of these cancellation coefficients, where m is the number of cancellation coefficients in this set, denotes rounding up; then change the amplitude A of the selected cancellation coefficients to a random value in the range [0.95A, 1.05A] until the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB. Then add the newly generated set of cancellation coefficients to the initial set C to form a new set C3;

[0093] Step S434: Determine the number of sets of cancellation coefficients in set C3. If it is greater than 4m, then delete several sets of the worst-performing cancellation coefficients until the number of elements in the set is less than or equal to 4m;

[0094] Step S435: Repeat steps S431 - S434 until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

[0095] By continuously optimizing the cancellation coefficients through the above steps, it can be ensured that the obtained cancellation coefficients can cancel the interference signal below the noise floor, thereby effectively removing the interference of the in-band nonlinearity of the uplink reception on the receiving array.

[0096] Thus, by using the obtained downlink channel set B and the cancellation coefficients of the uplink interference, combining them with the downlink signal to generate a cancellation signal with the same magnitude and opposite phase as the uplink interference, and adding or subtracting the generated cancellation signal from the uplink signal to affect the phase, the interference falling within the uplink band can be effectively eliminated.

[0097] Embodiment 2

[0098] As Figure 2 shown, this embodiment provides an adaptive receiving array intermodulation interference cancellation device, which at least includes a plurality of uplink channels, a plurality of downlink channels, and an interference estimation module; one end of the interference estimation module is connected after the DBF module of the transmitting channel for collecting data from the transmitting channels that need interference cancellation; one end is connected between the DAC + down-modulation module and the DBF module of the receiving channel for collecting data from all receiving channels.

[0099] Specifically, the interference estimation module includes:

[0100] A data acquisition unit for collecting data from all downlink channels and collecting data from the uplink channels that need interference cancellation;

[0101] An intermodulation signal processing unit, which is used to construct a fitted intermodulation signal by using a downlink signal and a power amplifier intermodulation model, and perform uplink shaping filtering on it to obtain a fitted intermodulation signal that only contains the uplink passband part;

[0102] A cross-correlation operation unit, which is used to perform a cross-correlation operation on the fitted intermodulation signal obtained after being processed by the intermodulation signal processing unit and the actual uplink interference signal, and compare the cross-correlation operation result with a preset threshold. If the cross-correlation result is greater than the threshold, it means that the intermodulation of this downlink channel affects the uplink reception, and then the set of all downlink channels that will interfere with the uplink reception is recorded as B;

[0103] An interference cancellation unit, which is used to use an optimization algorithm to estimate the cancellation coefficients of the downlink channel set B and the uplink interference, construct an anti-interference model by using the cancellation coefficients, combine the cancellation coefficients with the downlink signal in the anti-interference model to generate a cancellation signal with the same magnitude and opposite phase as the uplink interference, and add or subtract the generated cancellation signal from the uplink signal to affect the phase, so as to eliminate the interference falling within the uplink band.

[0104] Preferably, in the intermodulation signal processing unit, the used power amplifier intermodulation model is the Volterra series model, and its expression is as follows:

[0105] y(k) = y0 + ∑h1(m)u(k - m) + ∑h2(m1,m2)u(k - m1)u(k - m2) + …

[0106] where u(k) is the downlink signal, y(k) is the output of the Volterra series model, and h is the coefficient corresponding to the model;

[0107] In addition, this solution only focuses on the components of the signal falling within the uplink passband. Therefore, the formula of the actually used power amplifier intermodulation model is:

[0108] Y′(k) = y(k)G(t) where y(k) is the output of the Volterra series model; G(t) is the output of the uplink shaping filter; Y′(k) represents the output of the power amplifier intermodulation model, which is a fitted intermodulation signal that only contains the uplink passband part.

[0109] And since the power amplifier model is centered on the downlink signal frequency, and the uplink shaping filter is centered on the uplink signal frequency, in this embodiment, the frequency points of the two are also aligned to avoid spectral misalignment between the power amplifier and the filter, ensure the phase and frequency consistency of the signal during transmission, ensure that the power amplifier and the filter can work within the correct frequency bandwidth range, improve the signal quality, reduce the error caused by inaccurate frequency alignment, and make the constructed fitted intermodulation signal more accurate.

[0110] Preferably, in the cross-correlation operation unit, the cross-correlation operation formula is:

[0111]

[0112] where x * (k - t) represents the uplink signal; Y′(k) represents the output of the power amplifier intermodulation model; r yx (t) represents the cross-correlation result.

[0113] Using the above formula, the cross-correlation result between the filtered fitted intermodulation signal and the actual uplink interference signal can be calculated. Then, the cross-correlation operation result is compared with a preset threshold through the comparison component in the cross-correlation operation unit. When the cross-correlation result is greater than the threshold, it indicates that the intermodulation of the downlink channel affects the uplink reception; otherwise, it indicates that the intermodulation of the downlink channel has no effect on the uplink reception. Then, the set B of all downlink channels that interfere with the uplink reception is recorded, and then the obtained set B is sent to the interference cancellation unit for interference cancellation processing.

[0114] Preferably, in the interference cancellation unit, it further includes:

[0115] An interference cancellation coefficient acquisition component, which is used to subtract the output Y′(k) of the power amplifier intermodulation model from the actual uplink interference signal x(k) to obtain the error e(k) of the anti-interference model, and obtain several groups of interference cancellation coefficients H according to the error;

[0116] An interference cancellation coefficient selection component, which is used to select the n groups of interference cancellation coefficients with the best cancellation effect from several groups of interference cancellation coefficients to form a new initial set, denoted as the initial set C = [H1 H2 H3 … H n ;

[0117] An interference cancellation coefficient optimization component, which is used to optimize the interference cancellation coefficients in the initial set C until the obtained interference cancellation coefficients can cancel the interference signal below the noise floor.

[0118] Specifically, the processing flow in the interference cancellation coefficient optimization component includes:

[0119] First, select the two groups of interference cancellation coefficients with the best cancellation effect from the initial set C, then randomly exchange a coefficients among them, and calculate the cancellation error of the two new groups of interference cancellation coefficients. If the cancellation error of the new groups of interference cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, then add the newly generated groups of interference cancellation coefficients to the initial set C to form a new set C1;

[0120] Then, randomly select two sets of cancellation coefficients from set C1, randomly exchange a coefficients among them, calculate the cancellation error of the two sets of new cancellation coefficients. If the cancellation error of the new cancellation coefficients is better than that of the worst-performing group in the initial set C by more than 1 dB, add the newly generated set of cancellation coefficients to set C1 to form a new set C2.

[0121] Then, randomly select a set of cancellation coefficients from set C2, and then randomly select cancellation coefficients from this set, where m is the number of cancellation coefficients in this set, denotes rounding up; then change the amplitude A of the selected cancellation coefficients to a random value in the range [0.95A, 1.05A] until the cancellation error of the new cancellation coefficients is better than that of the worst-performing group in the initial set C by more than 1 dB, then add the newly generated set of cancellation coefficients to the initial set C to form a new set C3; and judge the number of sets of cancellation coefficients in set C3. If it is greater than 4m, delete several groups of the worst-performing cancellation coefficients until the number of elements in the set is less than or equal to 4m.

[0122] Finally, repeat the above steps until the obtained cancellation coefficients can cancel the interference signal below the noise floor, thus realizing the continuous optimization of the cancellation coefficients, ensuring that the obtained cancellation coefficients can cancel the interference signal below the noise floor, and effectively removing the interference of the in-band nonlinearity of the uplink reception to the receiving array.

[0123] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, rather than limitations on the specific implementation manners of the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the claims of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. An adaptive receiving array intermodulation interference cancellation method, characterized in that The method includes: S1: Collect data from all downlink channels and collect data from the uplink channels that need interference cancellation. S2: According to the collected data, use the downlink signal and the power amplifier intermodulation model to construct a fitted intermodulation signal, and perform uplink shaping filtering on it to obtain a fitted intermodulation signal that only contains the uplink passband part. S3: Perform cross-correlation operation on the filtered fitted intermodulation signal in step S2 and the actual uplink interference signal, and compare the cross-correlation operation result with a preset threshold. If the cross-correlation result is greater than the threshold, it indicates that the intermodulation of this downlink channel affects the uplink reception. Then, record the set of all downlink channels that will interfere with the uplink reception as B. S4: Use an optimization algorithm to estimate the downlink channel set B and the cancellation coefficient of the uplink interference. Use the cancellation coefficient to construct an anti-interference model. In the anti-interference model, combine the cancellation coefficient and the downlink signal to obtain a cancellation signal that is equal in magnitude and opposite in phase to the uplink interference. Add or subtract the generated cancellation signal from the uplink signal to affect the phase, thereby eliminating the interference falling within the uplink band.

2. The adaptive receiving array intermodulation interference cancellation method according to claim 1, wherein In the step S2, the power amplifier intermodulation model is the Saleh model or the Rapp model or the Volterra series model or other models.

3. An adaptive receiving array intermodulation interference cancellation method according to claim 2, characterized in that The power amplifier intermodulation model selects the Volterra series model, and obtains the actually used power amplifier intermodulation model for the component of the signal falling within the uplink passband. Its formula is: Y′(k) = y(k)G(t) where y(k) is the output of the Volterra series model; G(t) is the output of the uplink shaping filter; Y′(k) represents the output of the power amplifier intermodulation model, which is a fitted intermodulation signal that only contains the uplink passband part.

4. An adaptive receiving array intermodulation interference cancellation method according to claim 3, characterized in that, In the step S2, it also includes performing band-limiting operation on the power amplifier intermodulation model to align the frequency points of the power amplifier intermodulation model and the uplink shaping filter.

5. An adaptive receiving array intermodulation interference cancellation method according to claim 4, characterized in that In the step S3, the cross-correlation operation formula is: Among them, x * (k - t) represents the uplink signal; Y′(k) represents the output of the power amplifier intermodulation model; r yx (t) represents the cross-correlation result.

6. An adaptive receiving array intermodulation interference cancellation method according to claim 5, characterized in that, In the step S4, it includes: S41: Use the actual uplink interference signal x(k) minus the output Y′(k) of the power amplifier intermodulation model to obtain the error e(k) of the anti-interference model, and obtain several groups of cancellation coefficients according to the error. S42: Select the n cancellation coefficient groups with the best cancellation effect from several cancellation coefficient groups to form a new initial set, denoted as the initial set C = [H1H2H3…H n ; S43: Optimize the cancellation coefficients in the initial set C until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

7. The adaptive receiving array intermodulation interference cancellation method according to claim 6, characterized in that In the step S41, the obtaining of several cancellation coefficients according to the error includes: S411: Use an optimization algorithm to find a suitable cancellation coefficient h such that S412: Since the overdetermined equation has no unique solution, the least squares method is used to solve the approximate solution of the optimal cancellation coefficient, and several groups of cancellation coefficients H are obtained. Its formula is: H = (UU*) -1 U*X where U represents the downlink transmission signal; X represents the uplink reception signal.

8. An adaptive receiving array intermodulation interference cancellation method according to claim 6, characterized in that, In the step S43, the optimization process includes: S431: Select two sets of cancellation coefficients with the best cancellation effect from the initial set C, then randomly swap a coefficients among them, and calculate the cancellation error of the two new sets of cancellation coefficients. If the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, add the newly generated set of cancellation coefficients to the initial set C to form a new set C1. S432: Randomly select two sets of cancellation coefficients from the set C1, and randomly swap a coefficients among them. Calculate the cancellation error of the two new sets of cancellation coefficients. If the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, add the newly generated set of cancellation coefficients to the set C1 to form a new set C2. S433: Randomly select a set of cancellation coefficients from set C2, and then randomly select of these cancellation coefficients, where m is the number of cancellation coefficients in this set, represents rounding up; then change the amplitude A of the selected cancellation coefficients to a random value in the interval [0.95A, 1.05A], until the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst-performing group in the initial set C by more than 1 dB, then add the newly generated set of cancellation coefficients to the initial set C to form a new set C3; S434: Determine the number of sets of cancellation coefficients in the set C3. If it is greater than 4m, delete several sets of cancellation coefficients with the worst performance until the number of elements in the set is less than or equal to 4m. S435: Repeat steps S431 - S434 until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

9. An adaptive receiving array intermodulation interference cancellation device, characterized in that, The device at least includes several uplink channels, several downlink channels, and an interference estimation module. Among them, the interference estimation module includes: A data acquisition unit, which is used to acquire data from all downlink channels and acquire data from the uplink channels that need interference cancellation. An intermodulation signal processing unit, which is used to construct a fitting intermodulation signal using the downlink signal and the power amplifier intermodulation model, and perform uplink shaping filtering on it to obtain a fitting intermodulation signal that only contains the uplink passband part. A cross-correlation operation unit, which is used to perform cross-correlation operation on the fitting intermodulation signal obtained after being processed by the intermodulation signal processing unit and the actual uplink interference signal, and compare the cross-correlation operation result with a preset threshold. If the cross-correlation result is greater than the threshold, it means that the intermodulation of this downlink channel affects the uplink reception. Then, record the set of all downlink channels that will interfere with the uplink reception as B. An interference cancellation unit, which is used to estimate the cancellation coefficients of the downlink channel set B and the uplink interference using an optimization algorithm, construct an anti-interference model using the cancellation coefficients, combine the cancellation coefficients with the downlink signal in the anti-interference model to generate a cancellation signal with the same magnitude and opposite phase as the uplink interference, and add or subtract the generated cancellation signal from the uplink signal to affect the phase, so as to eliminate the interference falling within the uplink band.

10. An adaptive receiving array intermodulation interference cancellation device according to claim 9, characterized in that In the interference cancellation unit, there is also included: A cancellation coefficient acquisition component, which is used to obtain the error e(k) of the anti-interference model by subtracting the output Y′(k) of the power amplifier intermodulation model from the actual uplink interference signal x(k), and obtain several sets of cancellation coefficients according to the error. Cancellation coefficient selection component, which is used to select the n cancellation coefficient groups with the best cancellation effect from several groups of cancellation coefficients to form a new initial set, denoted as the initial set C = [H1H2H3…H n ; A cancellation coefficient optimization component, which is used to optimize the cancellation coefficients in the initial set C until the obtained cancellation coefficients can cancel the interference signal below the noise floor.

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