Open-loop method and device for removing interference of transmitting out-of-band nonlinearity on receiving array

Abstract

The invention relates to the technical field of antenna array transceiving interference removal, in particular to a method and device for removing interference of transmitting out-of-band nonlinearity on a receiving array in an open-loop mode, and the method comprises the steps: S1, finding out the transmitting predistortion coefficient of each channel with the minimum interference of a transmitting array on the receiving array through a search algorithm when the array is in a non-working state; and S2, in an array working state, the predistortion coefficient obtained in the step S1 is directly convolved with a downlink transmitting signal, so that the predistortion coefficient is applied to each transmitting channel to destroy coherence of transmitted non-linear signals. According to the invention, the out-of-band interference of transmitting to receiving in an antenna array is effectively solved, so that the demand of a transmitting channel on out-of-band rejection of a filter is greatly reduced, the power consumption, the volume and the weight of the array are reduced, and the efficiency of the array is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of antenna array receiving and transmitting interference removal, and more specifically, to an open-loop method and device for removing nonlinear interference of transmission out-of-band to a receiving array. Background Art

[0002] In a coplanar antenna array, when the antenna works in FDD mode, the transmitted signal will generate nonlinear spectra due to the nonlinear characteristics of the transmit channel. These spectra usually fall into the receive frequency band, and some energy will still remain even after the transmit and receive antennas are isolated and the transmit out-of-band filter suppresses them.

[0003] In non-array systems, such as a one-receive-one-transmit FDD RF system, the usual practice is that as long as the energy of the transmitted nonlinear spectrum falling into the receiving channel is lower than a certain threshold of the air noise floor at the input port of the receiving path, the impact on the receiving channel is considered negligible. Therefore, the out-of-band suppression of the filter at the transmit output port is usually increased to suppress interference to the receiving channel.

[0004] However, in an array system, even if the nonlinear spectrum emitted by each pair of transmitting and receiving antennas falls into the receiving channel below a certain threshold of the air noise floor, the coherence of the main signal transmitted by the multi-path causes its nonlinear spectrum to be coherent, which causes the spectrum falling into the receiving path to be coherent as well. Therefore, these coherent signals will be amplitude and phase weighted through the receiving array, thus being higher than the thermal noise combined by the entire receiving array, thereby affecting the signal-to-noise ratio of the receiving link.

[0005] Usually, the energy outside the transmission band is suppressed by a filter after the last amplifier stage of the transmission. However, increasing the out-of-band suppression of the filter will lead to a decrease in the gain within the transmission band and a corresponding increase in the size and weight of the filter, thereby affecting the efficiency, power consumption, size and weight of the transmission link.

[0006] In order not to affect the efficiency, power consumption and volume of the transmission link, a method is provided to solve the out-of-band interference problem of transmission on reception in the antenna array by pre-distorting the signals of each transmission path without imposing overly stringent requirements on the transmission filter. Summary of the invention

[0007] The present invention aims to overcome at least one defect (shortcoming) of the above-mentioned prior art and provides an open-loop method and device for removing out-of-band nonlinear interference of the transmitting array to the receiving array, which effectively solves the out-of-band interference of the transmitting on the receiving in the antenna array, greatly reduces the demand of the transmitting channel for the out-of-band suppression of the filter, reduces the power consumption, volume and weight of the array, and improves the efficiency of the array.

[0008] In a first aspect, the technical solution adopted by the present invention is an open-loop method for removing interference of nonlinearity out of the transmission band to a receiving array, the method comprising:

[0009] S1: When the array is not in operation, a search algorithm is used to find the transmit predistortion coefficients of each channel with the minimum interference from the transmit array to the receive array;

[0010] S2: When the array is in working state, the predistortion coefficient obtained in step S1 is directly convolved with the downlink transmission signal, so as to be applied to each transmission channel to destroy the coherence of the transmission nonlinear signal.

[0011] In the present application, the digital pre-distortion method is applied to the array. There is no need to suppress the out-of-band nonlinearity of each transmitting power amplifier. Instead, the transmitting antenna array normally forms a data beam, and the receiving channel receives the transmitted out-of-band leakage signal. The transmit pre-distortion coefficients of each channel with the smallest interference of the transmitting array on the receiving array are applied to each transmitting channel, thereby minimizing the transmit nonlinearity of the receiving channel. The pre-distortion coefficients are only for the out-of-band spectrum of the transmitted signal, and the coherence of the normal in-band signal is not destroyed, which does not affect the transmit and receive beams of the antenna array. Moreover, the pre-distortion coefficients are not only for a single power amplifier, but can be optimized on the basis of the entire receiving array, thereby effectively solving the out-of-band interference of the transmission on the reception in the antenna array, greatly reducing the demand for out-of-band suppression of the filter by the transmitting channel, reducing the power consumption, volume and weight of the array, and improving the efficiency of the array.

[0012] Preferably, in step S1, the search algorithm is a genetic algorithm.

[0013] By optimizing the pre-distortion coefficient of the transmitting array through a genetic algorithm, the interference to the receiving array is minimized, the signal quality of the communication system can be improved, the interference caused by nonlinear distortion can be reduced, and the spectrum efficiency can be improved. It can also adapt to different channel conditions and interference environments, ensuring good optimization effects in a dynamically changing communication environment.

[0014] Preferably, in step S1, a genetic algorithm is used to find the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array, including:

[0015] S31: Initialize the population and generate several different transmit predistortion coefficient combinations d = [d1, d2, ..., d m ], where m is the number of transmit channels and d is the transmit predistortion coefficient;

[0016] S32: Establishing a fitness function to calculate the fitness corresponding to each transmit predistortion coefficient combination;

[0017] S33: Generate a new transmit predistortion coefficient combination through iterative optimization of selection, crossover and mutation operations, then repeat the operation of step S32, recalculate the fitness corresponding to each new transmit predistortion coefficient combination, and output the optimal transmit predistortion coefficient combination when the termination condition is met.

[0018] By continuously iterating and updating the genetic algorithm, the optimal pre-distortion coefficient with minimum interference is finally obtained. Applying it to each transmitting channel can prevent the nonlinear spectrum generated by the transmitting channel from falling into the receiving frequency band and affecting the quality of the received signal, effectively avoiding interference with the received signal.

[0019] Preferably, in step S32, the fitness function is composed of several performance indicators, and can be optimized by adjusting the value of a weight coefficient according to different application requirements, wherein the value of the weight coefficient is greater than 0.

[0020] The more performance indicators included in the fitness function, and the importance of different performance indicators is adjusted by adjusting the value of the weight coefficient according to different application requirements, so that the group of pre-distortion coefficients reflected by the obtained fitness value has a better effect on interference and signal quality optimization, and ultimately the obtained pre-distortion coefficient is more ideal, making the antenna array more anti-interference.

[0021] Preferably, the fitness function at least includes the performance indicators of maximum signal-to-noise ratio, minimization of intermodulation distortion, minimization of interference power and minimization of mean square error, and the obtained fitness function formula is:

[0022]

[0023] Among them, P signal is the power of the signal; P noise is the power of the noise; IMD is the minimum intermodulation distortion; P interference is to minimize the interference power; MSE is to minimize the mean square error; ω1, ω2, ω3, ω4 are the weight coefficients of the above performance indicators respectively.

[0024] In the fitness function formula, these indicators can be balanced by setting different weight coefficients. For example, if SNR is more important, the weight of ω1 can be increased; if IMD is more important, the weight of ω2 can be increased accordingly, so as to output the optimal solution and obtain the optimal combination of transmit predistortion coefficients, thereby minimizing the interference of the transmit array to the receive array and optimizing the performance of the system.

[0025] Preferably, step S33 includes: selecting a transmit predistortion coefficient combination with higher fitness as a parent individual, then performing a crossover operation to generate a new transmit predistortion coefficient combination, then performing random mutation on some transmit predistortion coefficients in the new transmit predistortion coefficient combination to introduce new genetic information, and finally re-iterating the operations of steps S32-S33 until the optimal transmit predistortion coefficient combination is obtained.

[0026] Through the above operation, the diversity of transmit predistortion coefficients can be introduced to prevent the algorithm from falling into a local optimal solution, so that the obtained transmit predistortion coefficient combination is close to the global optimal solution, thereby applying it to various transmit channels to effectively improve the performance of the antenna array.

[0027] Preferably, in step S2, the predistortion coefficient obtained in step S1 is directly convolved with the downlink transmission signal, so as to be applied to each transmission channel to destroy the coherence of the transmission nonlinear signal, and the processing formula is:

[0028]

[0029] in, is the downlink transmission signal after pre-distortion processing; d i is the transmit predistortion coefficient of the i-th transmit channel; U i is the i-th downlink transmission signal.

[0030] By using the obtained optimal transmit predistortion coefficient and applying it to the transmit channel through the above formula, the interference of nonlinear distortion on the receiving array is effectively reduced, the spectrum efficiency is improved, and the signal quality of the communication system is improved.

[0031] Preferably, the termination condition is that the fitness reaches a preset threshold or reaches a maximum number of iterations. The termination condition can be selected according to actual needs to obtain the desired optimized transmission predistortion coefficient and reduce the impact of interference in the receiving array.

[0032] On the other hand, the present invention also provides an open-loop device for removing interference of nonlinearity outside the transmission band on the receiving array, the device at least comprising:

[0033] A parameter processing unit, used for finding out the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array by using a genetic algorithm when the array is not in working state;

[0034] The signal control unit is used to directly convolve the optimized pre-distortion system with the downlink transmission signal when the array is in working state, so as to apply it to each transmission channel to realize the pre-distortion processing of the signal.

[0035] In this device, the transmission predistortion coefficient of each channel is obtained through the parameter processing unit, and the digital predistortion method is applied to the array. There is no need to suppress the out-of-band nonlinearity of each transmitting power amplifier. Instead, the transmitting antenna array normally forms a data beam, and the receiving channel receives the transmitted out-of-band leakage signal. The transmission predistortion coefficient of each channel with the smallest interference of the transmitting array on the receiving array is applied to each transmitting channel, thereby minimizing the transmission nonlinearity of the receiving channel. The predistortion coefficient is only for the out-of-band spectrum of the transmitted signal, and the coherence of the normal in-band signal is not destroyed, which does not affect the transmit and receive beams of the antenna array. In addition, the predistortion coefficient is not only for a single power amplifier, but can be optimized on the basis of the entire receiving column, thereby effectively solving the out-of-band interference of transmission on reception in the antenna array, greatly reducing the demand for out-of-band suppression of the filter by the transmitting channel, reducing the power consumption, volume and weight of the array, and improving the efficiency of the array.

[0036] Preferably, the parameter processing unit includes:

[0037] Initialization component: Initialize the population and generate several different transmit predistortion coefficient combinations d = [d1, d2, ..., d m ], where m is the number of transmit channels and d is the transmit predistortion coefficient;

[0038] Fitness calculation component: establishes a fitness function and calculates the fitness corresponding to each transmit predistortion coefficient combination;

[0039] Optimization iteration component: It generates a new transmit pre-distortion coefficient combination through iterative optimization through selection, crossover and mutation operations, and then re-enters the fitness calculation component to perform fitness calculation, and outputs the optimal transmit pre-distortion coefficient combination when the termination condition is met;

[0040] Among them, in the fitness calculation component, the fitness function formula is:

[0041]

[0042] Among them, P signal is the power of the signal; P noise is the power of the noise; IMD is the minimum intermodulation distortion; P interference is to minimize the interference power; MSE is to minimize the mean square error; ω1, ω2, ω3, ω4 are the weight coefficients of the above performance indicators respectively.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The present invention applies digital predistortion to the array. It is not necessary to suppress the out-of-band nonlinearity of each transmitting power amplifier. Instead, the transmitting antenna array normally forms a data beam, and the receiving channel receives the transmitted out-of-band leakage signal. The transmission predistortion coefficients of each channel with the smallest interference of the transmitting array on the receiving array are applied to each transmitting channel, thereby minimizing the transmission nonlinearity of the receiving channel. The predistortion coefficient is only for the out-of-band spectrum of the transmitting signal, and the coherence of the normal in-band signal is not destroyed, which does not affect the transmit and receive beams of the antenna array. Moreover, the predistortion coefficient is not only for a single power amplifier, but can be optimized on the basis of the entire receiving array, thereby effectively solving the out-of-band interference of transmission on reception in the antenna array, greatly reducing the demand of the transmitting channel for out-of-band suppression of the filter, reducing the power consumption, volume and weight of the array, and improving the efficiency of the array. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 A schematic diagram of the method flow provided in this embodiment.

[0046] Figure 2 This is a schematic diagram of the device structure provided in this embodiment.

[0047] Figure 3 A schematic diagram of another device structure provided in this embodiment. DETAILED DESCRIPTION

[0048] The drawings of the present invention are only for illustrative purposes and should not be construed as limiting the present invention. In order to better illustrate the following embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; it is understandable to those skilled in the art that some well-known structures and their descriptions in the drawings may be omitted.

[0049] Example 1

[0050] like Figure 1 As shown, the technical solution adopted by the present invention in this embodiment is an open-loop method for removing the interference of nonlinearity outside the transmission band on the receiving array, and the method includes:

[0051] S1: When the array is not in operation, a search algorithm is used to find the transmit predistortion coefficients of each channel with the minimum interference from the transmit array to the receive array;

[0052] S2: When the array is in working state, the predistortion coefficient obtained in step S1 is directly convolved with the downlink transmission signal, so as to be applied to each transmission channel to destroy the coherence of the transmission nonlinear signal.

[0053] In the present application, the digital pre-distortion method is applied to the array. There is no need to suppress the out-of-band nonlinearity of each transmitting power amplifier. Instead, the transmitting antenna array normally forms a data beam, and the receiving channel receives the transmitted out-of-band leakage signal. The transmit pre-distortion coefficients of each channel with the smallest interference of the transmitting array on the receiving array are applied to each transmitting channel, thereby minimizing the transmit nonlinearity of the receiving channel. The pre-distortion coefficients are only for the out-of-band spectrum of the transmitted signal, and the coherence of the normal in-band signal is not destroyed, which does not affect the transmit and receive beams of the antenna array. Moreover, the pre-distortion coefficients are not only for a single power amplifier, but can be optimized on the basis of the entire receiving array, thereby effectively solving the out-of-band interference of the transmission on the reception in the antenna array, greatly reducing the demand for out-of-band suppression of the filter by the transmitting channel, reducing the power consumption, volume and weight of the array, and improving the efficiency of the array.

[0054] In this embodiment, a typical microstrip coplanar antenna pattern is provided, such as Figure 2 As shown, the blue one is the transmitting microstrip antenna, the light orange one is the receiving microstrip antenna, the transmitting and receiving are coplanar antennas, on the same PCB stack, sharing an antenna interface, and the typical value of the transmitting and receiving isolation is about 20dB. For example, if the maximum output peak power of the final power amplifier of the transmitting antenna can reach 39.5dBm, and the fallback uses an average power of 30dBm, the spectrum leakage of the transmission in the receiving frequency band is mainly the nonlinear intermodulation product of the transmitting signal. Due to different power amplifier characteristics, the nonlinear products are also different. For example, a reasonable nonlinear value of 60dBc of the 7th order nonlinearity is taken, that is, the average power of the transmission falling into the receiving is 30dBm-60dBm. c = -30dBm. If it is a 20M OFDM signal, its power spectral density is -30dBm-73dB = -103dBm / Hz. Usually, the S-segment dielectric cavity filter has a suppression degree of 60 to 70dBc when the transmit and receive isolation is 60MHz. For example, when the array gain of a large receiving antenna is 38dB, the total interference value received by the array is -103dBm / Hz-70dBc-20dBc+38dB = -155dBm / Hz. This value is much larger than the noise floor of the receiving array, which is about -174dBm / Hz of the spectral density.

[0055] Secondly, in addition to considering the interference of the same group of transmitting and receiving antennas, it is also necessary to consider the interference between the transmitting and receiving antennas of the entire array, and consider the coupling of all transmitting antennas to the same receiving antenna unit. This superposition is still a coherent superposition. After simulation and testing, it is found that the signal received by a single receiving antenna in the middle position is not only the previously estimated -103dBm / Hz-70dB-20dB=-193dBm / Hz, but it is increased by 10dB to -183dBm / Hz. The total interference received by the entire receiving array will also be further increased, that is, not only -155dBm / Hz, but close to -145dBm / Hz.

[0056] From the above discussion, it can be seen that the interference of the transmission band to the reception is coherent, so the higher the gain of the receiving antenna array, the greater the nonlinearity of the received transmission leakage. Therefore, in the present invention, a digital pre-distortion method is adopted. When the array is not working, a genetic algorithm is used to find the transmission pre-distortion coefficients of each path with the minimum interference of the transmitting array to the receiving array, and after recording them, these pre-distortion coefficients are applied to each transmission channel when the antenna is in the working state, thereby destroying the coherence of the transmitted nonlinear signal.

[0057] Preferably, in step S1, the search algorithm is a genetic algorithm.

[0058] By optimizing the pre-distortion coefficient of the transmitting array through a genetic algorithm, the interference to the receiving array is minimized, the signal quality of the communication system can be improved, the interference caused by nonlinear distortion can be reduced, and the spectrum efficiency can be improved. It can also adapt to different channel conditions and interference environments, ensuring good optimization effects in a dynamically changing communication environment.

[0059] Preferably, in step S1, a genetic algorithm is used to find the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array, including:

[0060] S31: Initialize the population and generate several different transmit predistortion coefficient combinations d = [d1, d2, ..., d m ], where m is the number of transmit channels and d is the transmit predistortion coefficient;

[0061] S32: Establishing a fitness function to calculate the fitness corresponding to each transmit predistortion coefficient combination;

[0062] S33: Generate a new transmit predistortion coefficient combination through iterative optimization of selection, crossover and mutation operations, then repeat the operation of step S32, recalculate the fitness corresponding to each new transmit predistortion coefficient combination, and output the optimal transmit predistortion coefficient combination when the termination condition is met.

[0063] By continuously iterating and updating the genetic algorithm, the optimal pre-distortion coefficient with minimum interference is finally obtained. Applying it to each transmitting channel can prevent the nonlinear spectrum generated by the transmitting channel from falling into the receiving frequency band and affecting the quality of the received signal, effectively avoiding interference with the received signal.

[0064] Preferably, in step S32, the fitness function is composed of several performance indicators, and can be optimized by adjusting the value of a weight coefficient according to different application requirements, wherein the value of the weight coefficient is greater than 0.

[0065] The more performance indicators included in the fitness function, and the importance of different performance indicators is adjusted by adjusting the value of the weight coefficient according to different application requirements, so that the group of pre-distortion coefficients reflected by the obtained fitness value has a better effect on interference and signal quality optimization, and ultimately the obtained pre-distortion coefficient is more ideal, making the antenna array more anti-interference.

[0066] Preferably, the fitness function at least includes the performance indicators of maximum signal-to-noise ratio, minimization of intermodulation distortion, minimization of interference power and minimization of mean square error, and the obtained fitness function formula is:

[0067]

[0068] Among them, P signal is the power of the signal; P noise is the power of the noise; IMD is the minimum intermodulation distortion; P interference is to minimize the interference power; MSE is to minimize the mean square error; ω1, ω2, ω3, ω4 are the weight coefficients of the above performance indicators respectively.

[0069] Among them, in the above formula Indicates maximizing the signal-to-noise ratio (SNR). The higher the SNR, the higher the fitness. Intermodulation distortion (IMD), interference power, and mean square error (MSE) are usually the goals that we want to minimize, so their weights should be negative. The smaller the intermodulation distortion, interference, and error, the better the system performance and the higher the fitness.

[0070] In the fitness function formula, the relative importance of these indicators in the fitness function can also be emphasized by increasing their weight coefficient values ​​or by adjusting the weight ratio between them. If a certain indicator is more critical to the optimization, it can be given a larger weight. For example, if SNR is more important, the weight of ω1 can be increased; if IMD is more important, the weight of ω2 can be increased accordingly, so as to output the optimal solution and obtain the optimal combination of transmit predistortion coefficients, thereby minimizing the interference of the transmit array to the receive array and optimizing the performance of the system.

[0071] Preferably, the fitness function formula may optionally further include performance indicators such as signal-to-interference ratio SIR and out-of-band power OOBP to determine the ideal degree of the transmit predistortion coefficient, and the resulting formula is as follows:

[0072]

[0073] Among them, for SNR (signal-to-noise ratio), it is usually hoped that the larger the SNR, the better, because it represents the quality of the signal and the clarity of the reception; for IMD (intermodulation distortion), the smaller the intermodulation distortion, the better, because it affects the signal quality; for Interference (interference power), the smaller the interference power, the better, reducing interference can improve the communication quality; for MSE (mean square error), the smaller the mean square error, the better, because it reflects the accuracy and error level of the system; for SIR (signal-to-interference ratio), the larger the signal-to-interference ratio, the better, because it represents the strength ratio of the signal to the interference, and a higher SIR helps to improve the anti-interference ability of the system; for OOBP (out-of-band power), the smaller the out-of-band power, the better, because high out-of-band power will cause spectrum pollution. Therefore, the weights for each target can be adjusted according to the actual application requirements and optimization goals.

[0074] Preferably, step S33 includes: selecting a transmit predistortion coefficient combination with higher fitness as a parent individual, then performing a crossover operation to generate a new transmit predistortion coefficient combination, then performing random mutation on some transmit predistortion coefficients in the new transmit predistortion coefficient combination to introduce new genetic information, and finally re-iterating the operations of steps S32-S33 until the optimal transmit predistortion coefficient combination is obtained.

[0075] Through the above operation, the diversity of transmit predistortion coefficients can be introduced to prevent the algorithm from falling into a local optimal solution, so that the obtained transmit predistortion coefficient combination is close to the global optimal solution, thereby applying it to various transmit channels to effectively improve the performance of the antenna array.

[0076] Preferably, in step S2, the predistortion coefficient obtained in step S1 is directly convolved with the downlink transmission signal, so as to be applied to each transmission channel to destroy the coherence of the transmission nonlinear signal, and the processing formula is:

[0077]

[0078] in, is the downlink transmission signal after pre-distortion processing; d i is the transmit predistortion coefficient of the i-th transmit channel; U i is the i-th downlink transmission signal.

[0079] By using the obtained optimal transmit predistortion coefficient and applying it to the transmit channel through the above formula, the interference of nonlinear distortion on the receiving array is effectively reduced, the spectrum efficiency is improved, and the signal quality of the communication system is improved.

[0080] Preferably, the termination condition is that the fitness reaches a preset threshold or reaches a maximum number of iterations. The termination condition can be selected according to actual needs to obtain the desired optimized transmission predistortion coefficient and reduce the impact of interference in the receiving array.

[0081] Example 2

[0082] like Figure 2 As shown, this embodiment provides an open-loop device for removing interference of nonlinearity outside the transmission band to the receiving array, and the device at least includes:

[0083] A parameter processing unit, used for finding out the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array by using a genetic algorithm when the array is not in working state;

[0084] The signal control unit is used to directly convolve the optimized pre-distortion coefficient with the downlink transmission signal when the array is in working state, so as to apply it to each transmission channel to realize the pre-distortion processing of the signal.

[0085] The parameter processing unit is connected between the receiving channel and the transmitting channel, and the signal control unit is arranged between the DBF module of the transmitting channel and the DAC+upper modulation module. Specifically, one end of the parameter processing unit is connected to the receiving DBF module, and the other end is connected to the signal control unit. In a non-working state, a genetic algorithm is used to find out the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array, and then the coefficients are sent to the signal control unit to perform predistortion processing on the transmitting channel when the array is in a working state, thereby reducing nonlinear interference in the transmitting array.

[0086] In this device, the transmission predistortion coefficient of each channel is obtained through the parameter processing unit, and the digital predistortion method is applied to the array. There is no need to suppress the out-of-band nonlinearity of each transmitting power amplifier. Instead, the transmitting antenna array normally forms a data beam, and the receiving channel receives the transmitted out-of-band leakage signal. The transmission predistortion coefficient of each channel with the smallest interference of the transmitting array on the receiving array is applied to each transmitting channel, thereby minimizing the transmission nonlinearity of the receiving channel. The predistortion coefficient is only for the out-of-band spectrum of the transmitted signal, and the coherence of the normal in-band signal is not destroyed, which does not affect the transmit and receive beams of the antenna array. In addition, the predistortion coefficient is not only for a single power amplifier, but can be optimized on the basis of the entire receiving column, thereby effectively solving the out-of-band interference of transmission on reception in the antenna array, greatly reducing the demand for out-of-band suppression of the filter by the transmitting channel, reducing the power consumption, volume and weight of the array, and improving the efficiency of the array.

[0087] Preferably, the parameter processing unit includes:

[0088] Initialization component: Initialize the population and generate several different transmit predistortion coefficient combinations d = [d1, d2, ..., d m ], where m is the number of transmit channels and d is the transmit predistortion coefficient;

[0089] Fitness calculation component: establishes a fitness function and calculates the fitness corresponding to each transmit predistortion coefficient combination;

[0090] Optimization iteration component: It generates a new transmit pre-distortion coefficient combination through iterative optimization through selection, crossover and mutation operations, and then re-enters the fitness calculation component to perform fitness calculation, and outputs the optimal transmit pre-distortion coefficient combination when the termination condition is met;

[0091] Among them, in the fitness calculation component, the fitness function formula is:

[0092]

[0093] Among them, P signal is the power of the signal; P noise is the power of the noise; IMD is the minimum intermodulation distortion; P interference is to minimize the interference power; MSE is to minimize the mean square error; ω1, ω2, ω3, ω4 are the weight coefficients of the above performance indicators respectively.

[0094] Example 3

[0095] On the basis of embodiments 1 and 2, an interference estimation module is further added in this embodiment to offset the influence of downlink intermodulation on uplink reception, so as to further improve the anti-interference performance of the antenna array by combining the two architectures. Specifically, Figure 3As shown, one end of the interference estimation module is connected to the channel control unit of the transmitting channel, and is used to collect data from the transmitting channel that needs to perform interference cancellation; one end is connected between the DAC+ down-modulation module and the DBF module of the receiving channel, and is used to collect data from all receiving channels.

[0096] Then, based on the collected data, optimization processing is performed in the interference estimation module to obtain the cancellation coefficients of the downlink channel and the uplink interference, and the cancellation coefficients are used to build an anti-interference model. In the anti-interference model, the cancellation coefficients are combined with the downlink signal to obtain a cancellation signal that is equal to the uplink interference in magnitude and opposite in phase. The generated cancellation signal is added or subtracted from the uplink signal to affect the phase, thereby eliminating the interference falling within the uplink band.

[0097] Specifically, the optimization process includes:

[0098] Step S41: constructing a fitting intermodulation signal using the downlink signal and the power amplifier intermodulation model according to the collected data, and performing uplink shaping filtering on the fitting intermodulation signal to obtain a fitting intermodulation signal containing only the uplink passband part;

[0099] Preferably, the power amplifier intermodulation model in this embodiment uses a Volterra series model, and the power amplifier intermodulation model actually used is obtained for the component of the signal falling in the uplink passband, and its formula is:

[0100] Y′(k)=y(k)G(t)

[0101] Among them, 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 containing only the uplink passband part.

[0102] And because the power amplifier model is centered on the downlink signal, and the uplink shaping filter is centered on the uplink signal, it is also necessary to perform band-limiting operation on the power amplifier intermodulation model to align the frequencies of the power amplifier intermodulation model and the uplink shaping filter.

[0103] Step S42: performing a cross-correlation operation on the fitted intermodulation signal filtered in step S41 and the actual uplink interference signal, and comparing the cross-correlation operation result with a preset threshold value. If the cross-correlation result is greater than the threshold value, it means that the intermodulation of the downlink channel has an impact on the uplink reception, and then the collection of all downlink channels that will interfere with the uplink reception is recorded as B;

[0104] Wherein, the cross-correlation calculation formula is:

[0105]

[0106] Among them, x *(kt) represents the uplink signal; Y′(k) represents the output of the power amplifier intermodulation model; r yx (t) represents the cross-correlation result.

[0107] Step S43: Use an optimization algorithm to estimate the cancellation coefficient of the downlink channel set B and the uplink interference, and use the cancellation coefficient to construct an anti-interference model. In the anti-interference model, the cancellation coefficient and the downlink signal are combined to obtain a cancellation signal that is equal to the uplink interference in magnitude and opposite in phase. The generated cancellation signal is added or subtracted from the uplink signal to affect the phase, thereby eliminating the interference within the uplink band.

[0108] Preferably, the using of the optimization algorithm to estimate the cancellation coefficient of the downlink channel set B and the uplink interference specifically includes:

[0109] S51: 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 a plurality of cancellation coefficient groups according to the error;

[0110] S52: Select n cancellation coefficient groups with the best cancellation effect from a number of cancellation coefficient groups to form a new initial set, recorded as initial set C = [H1H2H3 ... H n ];

[0111] S53: Optimizing the cancellation coefficients in the initial set C until the obtained cancellation coefficients can cancel the interference signal below the bottom noise.

[0112] Further preferably, in the step S51, obtaining a plurality of compensation coefficient groups according to the error comprises:

[0113] S511: Use optimization algorithm to find a suitable offset coefficient h so that

[0114]

[0115] S512: Since the overdetermined equation has no unique solution, the least square method is used to solve the approximate solution of the optimal offset coefficient, and several offset coefficient groups H are obtained, whose formula is:

[0116] H=(U*U H ) -1 U H X

[0117] Among them, U represents the downlink transmission signal; X represents the uplink reception signal.

[0118] Further preferably, in step S53, the optimization process includes:

[0119] S531: Select two groups of cancellation coefficients with the best cancellation effect from the initial set C, then randomly exchange a coefficients therein, and calculate the cancellation errors 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 group in the initial set C by more than 1 dB, then add the newly generated cancellation coefficient group to the initial set C to form a new set C1;

[0120] S532: Randomly select two groups of cancellation coefficients in set C1, and randomly exchange a coefficients therein, calculate the cancellation errors of the two new groups of cancellation coefficients, and if the cancellation error of the new cancellation coefficients is better than the cancellation error of the worst performance group in the initial set C by more than 1 dB, then add the newly generated cancellation coefficient group to set C1 to form a new set C2;

[0121] S533: Randomly select a set of offset coefficients from set C2, and then randomly select The number of offset coefficients is m, Indicates rounding up; then the amplitude A of the selected cancellation coefficients is changed to a random value in the interval [0.95A, 1.05A] until the cancellation error of the new cancellation coefficient is more than 1dB better than the cancellation error of the worst performance group in the initial set C, then the newly generated cancellation coefficient group is added to the initial set C to form a new set C3;

[0122] S534: Determine the number of cancellation coefficient groups in the set C3. If the number is greater than 4m, delete several groups of cancellation coefficients with the worst performance until the elements of the set are less than or equal to 4m.

[0123] S535: Repeat steps S531-S534 until the obtained cancellation coefficient can cancel the interference signal below the noise floor.

[0124] Therefore, in this embodiment, while embodiments 1 and 2 effectively solve the out-of-band interference of transmission to reception in the antenna array by adopting digital pre-distortion, digital interference cancellation is further combined to eliminate the interference falling within the uplink band. The two architectures are combined to further improve the anti-interference performance of the antenna array, thereby greatly reducing the demand for out-of-band suppression of the filter in the transmission channel, reducing the power consumption, volume, and weight of the array, and improving the efficiency of the array.

[0125] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the technical solution of the present invention, and are not intended to limit the specific implementation methods of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. An open-loop method for removing nonlinear interference from out-of-band transmission to a receiving array, characterized in that: The method comprises: S1: When the array is not in operation, a search algorithm is used to find the transmit predistortion coefficients of each channel with the minimum interference from the transmit array to the receive array; S2: When the array is in working state, the predistortion coefficient obtained in step S1 is directly convolved with the downlink transmission signal, so as to be applied to each transmission channel to destroy the coherence of the transmission nonlinear signal.

2. The method of removing the interference of nonlinearity out of the transmission band to the receiving array in an open loop according to claim 1, characterized in that: In step S1, the search algorithm is a genetic algorithm.

3. The method of removing the interference of nonlinearity out of the transmission band to the receiving array in an open loop according to claim 2, characterized in that: In step S1, a genetic algorithm is used to find the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array, including: S31: Initialize the population and generate several different transmit predistortion coefficient combinations d = [d1, d2, ..., d m ], where m is the number of transmit channels and d is the transmit predistortion coefficient; S32: Establishing a fitness function to calculate the fitness corresponding to each transmit predistortion coefficient combination; S33: Generate a new transmit predistortion coefficient combination through iterative optimization of selection, crossover and mutation operations, then repeat the operation of step S32, recalculate the fitness corresponding to each new transmit predistortion coefficient combination, and output the optimal transmit predistortion coefficient combination when the termination condition is met.

4. The method of removing the interference of nonlinearity out of the transmission band to the receiving array in an open loop according to claim 3, characterized in that: In step S32, the fitness function is composed of several performance indicators, and can be optimized by adjusting the value of the weight coefficient according to different application requirements, wherein the value of the weight coefficient is greater than 0.

5. The method of removing the interference of nonlinearity out of the transmission band to the receiving array in an open loop according to claim 4, characterized in that: The fitness function at least includes the performance indicators of maximum signal-to-noise ratio, minimization of intermodulation distortion, minimization of interference power and minimization of mean square error. The obtained fitness function formula is: Among them, P signal is the power of the signal; P noise is the power of the noise; IMD is the minimum intermodulation distortion; P interference is to minimize the interference power; MSE is to minimize the mean square error; ω1, ω2, ω3, ω4 are the weight coefficients of the above performance indicators respectively.

6. The method of removing the interference of nonlinearity out of the transmission band to the receiving array in an open loop according to claim 5, characterized in that: The step S33 includes: selecting a transmit predistortion coefficient combination with a higher fitness as a parent individual, then performing a crossover operation to generate a new transmit predistortion coefficient combination, then performing random mutation on some transmit predistortion coefficients in the new transmit predistortion coefficient combination to introduce new genetic information, and finally re-iterating the operations of steps S32-S33 until the optimal transmit predistortion coefficient combination is obtained.

7. The open-loop method for removing nonlinear interference of transmission out-of-band to receiving array according to claim 6, characterized in that: In step S2, the predistortion coefficient obtained in step S1 is directly convolved with the downlink transmission signal, so as to be applied to each transmission channel to destroy the coherence of the transmission nonlinear signal. The processing formula is: in, is the downlink transmission signal after pre-distortion processing; d i is the transmit predistortion coefficient of the i-th transmit channel; U i is the i-th downlink transmission signal.

8. The open-loop method for removing nonlinear interference of transmission out-of-band to receiving array according to any one of claims 1 to 7, characterized in that: The termination condition is that the fitness reaches a preset threshold or reaches a maximum number of iterations.

9. An open-loop device for removing nonlinear interference from out-of-band transmission to a receiving array, characterized in that: The device at least comprises: A parameter processing unit, used for finding out the transmission predistortion coefficients of each channel with the minimum interference of the transmitting array to the receiving array by using a genetic algorithm when the array is not in working state; The signal control unit is used to directly convolve the optimized pre-distortion coefficient with the downlink transmission signal when the array is in working state, so as to apply it to each transmission channel to realize signal pre-distortion processing.

10. The open-loop device for removing nonlinear interference of transmission out-of-band to receiving array according to claim 9, characterized in that: The parameter processing unit includes: Initialization component: Initialize the population and generate several different transmit predistortion coefficient combinations d = [d1, d2, ..., d m ], where m is the number of transmit channels and d is the transmit predistortion coefficient; Fitness calculation component: establishes a fitness function and calculates the fitness corresponding to each transmit predistortion coefficient combination; Optimization iteration component: It generates a new transmit pre-distortion coefficient combination through iterative optimization through selection, crossover and mutation operations, and then re-enters the fitness calculation component to perform fitness calculation, and outputs the optimal transmit pre-distortion coefficient combination when the termination condition is met; Among them, in the fitness calculation component, the fitness function formula is: Among them, P signal is the power of the signal; P noise is the power of the noise; IMD is the minimum intermodulation distortion; P interference is to minimize the interference power; MSE is to minimize the mean square error; ω1, ω2, ω3, ω4 are the weight coefficients of the above performance indicators respectively.

Images