A design method, apparatus and equipment for a prototype filter for low-Earth orbit satellites

Abstract

The present invention provides a design method, device and equipment for a prototype filter of a low-orbit satellite, the method comprising: constructing a dynamic space-time non-stationary phased array satellite channel response matrix, designing a multi-phase cascade network of a subcarrier filter group and a phased array multi-carrier filter group, completing the time-domain equivalent superposition of a sampling-scaled linear minimum mean square error channel estimation and a filter group, establishing an objective function and a constraint of a prototype filter under a dynamic space-time non-stationary satellite channel, and obtaining the prototype filter coefficients under the space-time non-stationary satellite channel by solving the constrained objective function, thereby reconstructing a satellite FBMC prototype filter. The optimized design of the prototype filter of the low-orbit satellite channel is achieved, and the receiving channel estimation performance of the FBMC system under the condition of a phased array low-orbit satellite is improved.

Description

Technical Field

[0001] The present invention relates to the field of wireless communication technology, and in particular to a design method, device and equipment for a low-orbit satellite prototype filter. Background Art

[0002] With the advancement of science and technology, 5G technology has gradually developed on a large scale in recent years. The 6G vision proposes the important vision of achieving global high-speed mobile communication coverage. The key lies in how to improve the spectrum utilization efficiency and user multiplexing capabilities while ensuring reliable connection between users and satellites based on satellite communication payloads.

[0003] The low-orbit satellite mobile communication system consists of satellite constellations, gateway earth stations, system control centers, network control centers, and user units. The low-orbit satellite channel is more complex than the ground channel, and the design of the prototype filter in the low-orbit satellite channel is more difficult. Generally, the design of the prototype filter only considers the subcarrier interference and carrier interference at the transmitter, which in turn affects the performance of the satellite channel.

[0004] Therefore, how to propose a prototype filter design that can improve the performance of low-orbit satellite channels is an urgent problem to be solved in this field. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a method, apparatus and device for designing a prototype filter of a low-orbit satellite to eliminate or improve one or more defects existing in the prior art.

[0006] One aspect of the present invention provides a method for designing a prototype filter for a low-orbit satellite, the method comprising the following steps:

[0007] Construct the channel response matrix of dynamic space-time non-stationary phased array low-orbit satellite;

[0008] Design polyphase cascade networks of subcarrier filter banks and phased array multicarrier filter banks;

[0009] Performing channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine a root mean square error of the low-orbit satellite channel;

[0010] Based on the root mean square error, an objective function and a constraint amount of a low-orbit satellite prototype filter are established;

[0011] According to the constraint amount, the objective function is optimized to obtain coefficients of the prototype filter.

[0012] In some embodiments of the present invention, constructing a dynamic space-time non-stationary phased array low-orbit satellite channel response matrix includes:

[0013] Construct a normalized correlation model of multi-level channel fading and the behavioral response of LEO satellite phased arrays to multi-carrier signals;

[0014] The normalized correlation model is combined with the behavioral response to obtain the dynamic space-time non-stationary phased array low-orbit satellite channel response matrix.

[0015] In some embodiments of the present invention, the design of a polyphase cascade network of a subcarrier filter bank and a phased array multicarrier filter bank includes:

[0016] Extract the input-output relationship of the FBMC subcarrier filter bank and construct a subcarrier filter bank multiphase network;

[0017] Extract the input-output relationship of the phased array multi-carrier filter group and construct the phased array multi-carrier filter network;

[0018] The subcarrier group multi-phase network and the phased array multi-carrier filter network are cascaded through a weighted mapping relationship to obtain the multi-phase cascade network.

[0019] In some embodiments of the present invention, the performing channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine the root mean square error of the low-orbit satellite channel includes:

[0020] According to the demodulation process when FBMC adopts a multi-phase cascade network structure, a receiving end interpretation filter bank is established;

[0021] Using a sliding window to segment the output signal matrix of the interpretation filter bank, and performing channel estimation on the segmented signal sub-matrices respectively to obtain a channel estimation response matrix of each signal sub-matrix;

[0022] Merging the channel estimation response arrays of each signal sub-array to obtain a channel estimation result of the output result of the interpretation filter bank;

[0023] A root mean square error of the channel estimation is determined according to the channel estimation result and the channel estimation value of the target channel response.

[0024] In some embodiments of the present invention, establishing the objective function and constraint of the low-orbit satellite prototype filter based on the root mean square error includes:

[0025] The root mean square error is solved by using a minimum function to construct an objective function of the low-orbit satellite prototype filter;

[0026] Constructing a first constraint of the objective function based on the power spectrum and main lobe energy of the prototype filter;

[0027] A second constraint of the objective function is constructed based on the frequency response function of the prototype filter.

[0028] In some embodiments of the present invention, the method further comprises:

[0029] The structural parameters of the prototype filter and the polyphase cascade network of the subcarrier filter group and the phased array multi-carrier filter group are determined based on the coefficients of the prototype filter.

[0030] Another aspect of the present invention provides a design device for a low-orbit satellite prototype filter, the device comprising:

[0031] The response matrix construction module is used to construct the channel response matrix of the dynamic space-time non-stationary phased array low-orbit satellite;

[0032] Cascade network building module for designing polyphase cascade networks of subcarrier filter banks and phased array multicarrier filter banks;

[0033] A channel estimation module, configured to perform channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network, and determine a root mean square error of the low-orbit satellite channel;

[0034] An objective function building module is used to establish an objective function and a constraint of a low-orbit satellite prototype filter based on the root mean square error;

[0035] The filter coefficient determination module is used to optimize the objective function according to the constraint amount to obtain the coefficients of the prototype filter.

[0036] In some embodiments of the present invention, the device also includes a filter and cascade network design module, which is used to determine the structural parameters of the prototype filter and the multi-phase cascade network of the subcarrier filter group and the phased array multi-carrier filter group based on the coefficients of the prototype filter.

[0037] Another aspect of the present invention provides a design device for a low-orbit satellite prototype filter, comprising a processor and a memory, wherein the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the device implements the above-mentioned design method for the low-orbit satellite prototype filter.

[0038] Another aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned method for designing a prototype filter for a low-orbit satellite.

[0039] The present invention provides a design method, device and equipment for a prototype filter of a low-orbit satellite. The method constructs a dynamic space-time non-stationary phased array satellite channel response matrix, designs a multi-phase cascade network of a subcarrier filter group and a phased array multi-carrier filter group, completes the time domain equivalent superposition of the sampling scaled linear minimum mean square error channel estimation and the filter group, establishes the objective function and constraint of the prototype filter under the dynamic space-time non-stationary satellite channel, obtains the prototype filter coefficients under the space-time non-stationary satellite channel by solving the objective function with constraints, and then reconstructs the satellite FBMC prototype filter. The optimization design of the prototype filter of the low-orbit satellite channel is realized, and the receiving channel estimation performance of the FBMC system under the condition of a phased array low-orbit satellite is improved.

[0040] Additional advantages, purposes, and features of the present invention will be described in part in the following description, and will become apparent to those skilled in the art after studying the following, or may be learned from the practice of the present invention. The purposes and other advantages of the present invention may be achieved and obtained by the structures specifically indicated in the specification and the accompanying drawings.

[0041] Those skilled in the art will appreciate that the objectives and advantages that can be achieved with the present invention are not limited to the above specific description, and the above and other objectives that can be achieved by the present invention will be more clearly understood from the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings described herein are used to provide a further understanding of the present invention, constitute a part of this application, and do not constitute a limitation of the present invention. The components in the drawings are not drawn to scale, but are only for illustrating the principles of the present invention. In order to facilitate the illustration and description of some parts of the present invention, the corresponding parts in the drawings may be enlarged, that is, they may become larger relative to other components in the exemplary device actually manufactured according to the present invention. In the drawings:

[0043] Figure 1 It is a schematic flow chart of a design method of a prototype filter for a low-orbit satellite provided in one embodiment of this specification;

[0044] Figure 2 is a schematic diagram of a flow chart of a low-orbit satellite prototype filter design in another embodiment of the present specification;

[0045] Figure 3 It is a schematic diagram of the module structure of an embodiment of a design device for a prototype filter for a low-orbit satellite provided in this specification;

[0046] Figure 4 It is a schematic diagram of the module structure of another embodiment of the design device of the low-orbit satellite prototype filter provided in this specification;

[0047] Figure 5It is a hardware structure block diagram of a design server for a low-orbit satellite prototype filter in one embodiment of this specification. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0049] It should also be noted that, in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the solutions according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0050] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, elements, steps or components, but does not exclude the presence or addition of one or more other features, elements, steps or components.

[0051] It should also be noted that, unless otherwise specified, the term “connection” herein may refer not only to a direct connection but also to an indirect connection involving an intermediate.

[0052] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar components, or the same or similar steps.

[0053] The main focus of the embodiments of this specification is the design of a low-orbit satellite FBMC prototype filter for perfect reconstruction under a space-time non-stationary channel for low-orbit satellite Internet. The 6G vision proposes an important vision to achieve global high-speed mobile communication coverage. The key lies in how to improve the spectrum utilization efficiency and user multiplexing capabilities based on the premise of ensuring reliable connection between users and satellites based on satellite communication payloads. The general idea is to introduce phased array antennas and combine the air interface waveform of ground 5G NR (New Radio) to improve the OFDM (Orthogonal Frequency Division Multiplexing) air interface waveform of 5G NR based on the characteristics of satellite payloads, or integrate the design advantages of the 5GNR communication system based on the MF-TDMA system of DVB (Digital Video Broadcasting). At present, the idea of ​​innovating the low-orbit satellite air interface communication system based on the 5G NR communication system has become mainstream.

[0054] In the evolution of the OFDM air interface system of terrestrial 5G NR, waveforms such as GFDM (Generalized Frequency Division Multiplexing), UFMC (Universal Filtered Multi-Carrier), and FBMC (FBMC Filter-bank Multicarrier) have become very promising new alternatives. The main starting points are: 1) OFDM uses rectangular filters to filter subcarriers, and the subcarrier energy out-of-band leakage is serious. It is necessary to limit the out-of-band energy leakage to improve the degree of energy concentration in the frequency domain; 2) OFDM symbol phase uses random mapping, which is prone to continuous same phase modulation, resulting in excessive peak-to-average ratio. It is necessary to take certain measures to reduce the peak-to-average ratio of OFDM signals; 3) OFDM symbols are mainly carried by mutually continuous and strictly orthogonal subcarriers. When there is a carrier frequency offset that cannot be corrected, the frequency domain orthogonality of the subcarrier will be destroyed, resulting in serious inter-symbol interference, and the OFDM system needs to be effectively compensated for the frequency offset. The idea behind new alternative waveforms such as GFDM, UFMC, and FBMC is to effectively limit the sidelobes of the subcarriers by designing appropriate subband filter groups. At the same time, certain channel influences are considered in the prototype and design of the subband filters to improve the adaptability of the alternative waveforms to changing channels.

[0055] Considering that the FBMC waveform has a wider and more flexible waveform optimization potential compared to GFDM and UFMC, the embodiments of this specification mainly select FBMC as the main alternative waveform for low-orbit satellite Internet. In fact, judging from the current research status at home and abroad, the current application of the FBMC waveform in low-orbit satellite Internet is still in the initial stage of exploration. Based on this, the embodiments of this specification mainly start from the actual conditions of the low-orbit satellite channel, combined with the key points that need to be considered in the optimization design of FBMC, to solve some technical problems of the application of FBMC waveform in low-orbit satellite Internet.

[0056] In the embodiments of this specification, full consideration is given to the differences between phased array low-orbit satellite channels and ground channels, and the prototype filter design of FBMC is extended from the constraints between subcarriers to the constraints between phased array multi-carriers, forming a two-stage cascaded multi-phase control network architecture. Furthermore, by constructing a multi-phase decomposition function of the channel model of the phased array low-orbit satellite Internet, a dynamic space-time non-stationary satellite channel response matrix is ​​obtained, and then a linear smoothing minimum root mean square error channel estimation model is jointly established to construct an optimal control problem with the minimum MSE (Mean Squared Error) of the channel estimation, which satisfies the constraints of out-of-band leakage restriction, effective reconstruction restriction, and signal response space-time variation range restriction. Finally, by solving the constrained optimization problem, a satellite FBMC prototype filter design strategy that satisfies perfect reconstruction under space-time non-stationary satellite channels is obtained.

[0057] The low-orbit phased array antenna needs to synthesize multi-channel multi-carrier signals before transmitting signals. The prototype filter group will still need to be re-optimized after optimizing the sub-band out-of-band leakage. In addition, the low-orbit satellite channel is more complex than the ground channel. The actual performance gain of FBMC needs to be reflected by the adaptability to the channel. The embodiment of this specification jointly designs the phased array satellite channel estimation and the FBMC prototype filter to improve the receiving channel estimation performance of the phased array low-orbit satellite.

[0058] Figure 1 FIG. 1 is a flow chart of a design method for a prototype filter of a low-orbit satellite provided in one embodiment of the present specification. Figure 1 As shown, in one embodiment of the design method of the low-orbit satellite prototype filter provided in this specification, the method can be applied to terminal devices such as computers, tablet computers, servers, smart phones, smart wearable devices, etc., and the method may include the following steps:

[0059] Step 102: construct a dynamic space-time non-stationary phased array low-orbit satellite channel response matrix.

[0060] In the specific implementation process, the embodiments of this specification are aimed at the prototype filter design of low-orbit satellites. First, a dynamic space-time non-stationary satellite channel response matrix is ​​constructed, and a joint response correlation relationship is established between the satellite signal attenuation through on-board satellite nonlinear devices, path attenuation, large dynamic Doppler frequency offset attenuation, cloud and rain attenuation, and shadow attenuation.

[0061] In some embodiments of this specification, the construction of a dynamic space-time non-stationary phased array low-orbit satellite channel response matrix includes:

[0062] Construct a normalized correlation model of multi-level channel fading and the behavioral response of LEO satellite phased arrays to multi-carrier signals;

[0063] The normalized correlation model is combined with the behavioral response to obtain the dynamic space-time non-stationary phased array low-orbit satellite channel response matrix.

[0064] In the specific implementation process, Figure 2 FIG. 1 is a flow chart of designing a prototype filter for a low-orbit satellite according to another embodiment of the present specification. Figure 2 As shown in , when constructing the low-orbit satellite channel response matrix, we can first construct a normalized correlation model of multi-level channel fading, then establish the behavioral response of the low-orbit satellite phased array antenna to multi-carrier signals, and finally combine path loss, shadow fading, Doppler effect, cloud and rain fading, etc. to obtain the dynamic space-time non-stationary phased array satellite channel response matrix. Figure 2 The specific process can be referred to as follows:

[0065] (1) Construct a normalized correlation model of multi-level channel fading: Design a model including power frequency Phase Channel response expression model is a closed set of global parameters, that is, the total link channel fading model is If the fading of each channel of the phased array low-orbit satellite is considered to be relatively independent, then The path loss Clouds and rain fade Doppler fading Shadow Fading Multipath Fading Each type of fading is expressed as a corresponding closed set, forming a relatively independent Waiting for response.

[0066] Sets the amplitude extraction factor for a generic channel response Can be used to extract the amplitude of different channel fading; set a frequency extraction factor for a common channel response Can be used to extract the frequencies of different channel fading; set a phase extraction factor for a common channel response It can be used to extract the phase of different channel fading. Therefore, each parameter of the normalized correlation model can be extracted from each fading and the sum of the corresponding parameters, then:

[0067]

[0068]

[0069]

[0070] Specifically, corresponding to each type of fading, the specific processing can be as follows:

[0071] 1) Low-orbit satellite path loss According to the principle that the longer the path, the greater the loss, it can be concluded that the path loss will affect the value of the amplitude parameter. The higher the frequency, the greater the loss. It can be seen that the path loss will affect the value of the frequency parameter. It has no direct relationship with the phase.

[0072] 2) Cloud and rain fading of low-orbit satellites According to the higher the total liquid water column content in the air, the lower the satellite elevation angle, the more serious the cloud and rain fading, it can be concluded that cloud and rain fading will affect the amplitude parameter value. The higher the frequency, the greater the attenuation coefficient and the more serious the cloud and rain fading. It can be seen that cloud and rain fading will affect the value of frequency parameters. It has no direct relationship with the phase.

[0073] 3) Doppler fading of low-orbit satellites According to the fact that the greater the satellite moving speed, the greater the Doppler frequency shift, it can be concluded that the Doppler frequency shift will affect the amplitude parameter value. The higher the operating frequency, the greater the Doppler frequency shift. It can be seen that the Doppler frequency shift will affect the value of the frequency parameter. It has no direct relationship with the phase.

[0074] 4) Low-orbit satellite shadow fading According to the fact that the larger the obstacle width, the more serious the shadow fading, it can be concluded that shadow fading will affect the value of the amplitude parameter. The higher the working frequency, the more serious the shadow fading is. It can be seen that shadow fading will affect the value of frequency parameters. It has no direct relationship with the phase.

[0075] 5) Multipath fading of low-orbit satellites According to the fact that the greater the receiver moving speed, the greater the difference in multipath arrival angles, the greater the Doppler spread, and the more serious the fast fading, it can be concluded that multipath fading will affect the amplitude parameter value. The higher the operating frequency, the greater the Doppler spread and the more severe the fast fading. It can be seen that multipath fading will affect the value of frequency parameters. The greater the difference in multipath transmission distance, the greater the delay spread, and the more serious the frequency selective fading. It can be concluded that multipath fading will affect the value of the phase parameter.

[0076] (2) Establish the behavioral response of low-orbit satellite phased array antennas to multi-carrier signals:

[0077] Build a power frequency Phase Behavior response expression model of phased array antennas for low-orbit satellites It is expressed as:

[0078]

[0079] Among them, h Phasedarray is a closed set of global parameters. The behavioral response of the low-orbit satellite phased array antenna to the multi-carrier signal is divided into the beamforming response and the radiation response after the phased array antenna beam is transmitted. Each response is expressed as a corresponding closed set to form a relatively independent h beamforming and h radiate The beamforming response is expressed as:

[0080]

[0081] Phased Array Antenna Radiated Response It is expressed as:

[0082] Setting a general LEO satellite phased array antenna behavioral response amplitude extraction factor Can be used to extract the magnitude of two phased array antenna responses; set a frequency extraction factor for a common channel response Can be used to extract the frequency of two phased array antenna responses; set the phase extraction factor of a common channel response It can be used to extract the phase of the two phased array antenna responses. Therefore, each parameter of the normalized correlation model can be extracted from each response and the corresponding parameter value, then,

[0083]

[0084]

[0085]

[0086] Specifically, corresponding to each phased array antenna response, the specific processing can be as follows:

[0087] 1) Beamforming response of phased array antennas of low-orbit satellites According to the low-orbit satellite phased array antenna, the transmission power of each element can be flexibly adjusted, and it can be obtained that beamforming will affect the amplitude parameter value. As the phase of each element signal of the low-orbit satellite phased array antenna changes, the direction of the signal transmitted by each element also changes accordingly. It can be seen that the path loss will affect the value of the phase parameter. It has no direct relationship with frequency,

[0088] 2) Radiation response of low-orbit satellite phased array antenna According to the transmission signals of each element of the low-orbit satellite phased array antenna, they are combined into multiple beams in different target directions. After the combination, the beam power increases accordingly. It can be seen that the beam radiation will affect the amplitude parameter value. Since each signal is assigned a different phase in the beamforming stage, the combined transmission signals of each element of the phased array antenna will cause the phase of each beam to change accordingly. It can be seen that path loss will affect the value of the phase parameter. It has no direct relationship with frequency,

[0089] (3) Jointly obtain the dynamic space-time non-stationary phased array satellite channel response matrix: The multi-level fading model is combined with the low-orbit satellite phased array antenna response to establish the dynamic space-time non-stationary phased array satellite channel response matrix.

[0090] The embodiments of this specification fully consider the differences between the phased array low-orbit satellite channel and the ground channel, and extend the prototype filter design of FBMC from the constraints between subcarriers to the constraints between phased array multi-carriers, forming a two-stage cascaded multi-phase control network architecture, and further constructing the multi-phase decomposition function of the channel model of the phased array low-orbit satellite Internet to obtain the dynamic space-time non-stationary satellite channel response matrix. Based on the behavioral response of the phased array antenna to multi-carrier signals, etc., the low-orbit satellite channel response matrix is ​​constructed, which lays a data foundation for the joint design of the phased array and the prototype filter.

[0091] Step 104: design a polyphase cascade network of a subcarrier filter group and a phased array multi-carrier filter group.

[0092] In the specific implementation process, the design of the subcarrier filter group is mainly based on two principles, namely, minimum out-of-band leakage power and filter sampling Nyquist criterion, to optimize the filter width and overlap of the prototype filter group. This optimized single-channel signal still needs to be merged with other multi-channel signals, and multiple carriers pass through the phased array antenna to form a space-division multiplexed synthetic carrier. Therefore, for the phased array, the optimization of carrier performance should be fully reflected in the filter group's suppression of out-of-band leakage for each combined carrier. Based on this, the embodiment of this specification solves the application of FBMC filters in phased array low-orbit satellite channels by constructing a cascaded multi-phase network of multi-carrier phased array responses and sub-band filter groups.

[0093] In some embodiments of this specification, the design of a multi-phase cascade network of a subcarrier filter bank and a phased array multicarrier filter bank includes:

[0094] Extract the input-output relationship of the FBMC subcarrier filter bank and construct a subcarrier filter bank multiphase network;

[0095] Extract the input-output relationship of the phased array multi-carrier filter group and construct the phased array multi-carrier filter network;

[0096] The subcarrier group multi-phase network and the phased array multi-carrier filter network are cascaded through a weighted mapping relationship to obtain the multi-phase cascade network.

[0097] In the specific implementation process, the input-output relationship of the FBMC subcarrier filter group is extracted to construct a polyphase network, and then the input-output relationship of the phased array multicarrier filter group is extracted to construct a beamforming network. Finally, the polyphase network of the FBMC subcarrier filter group and the beamforming network of the phased array multicarrier filter group are cascaded through a weighted mapping relationship. Figure 2 The specific process can be referred to as follows:

[0098] (1) Extract the input-output relationship of the FBMC subcarrier filter bank and construct a subcarrier filter bank multiphase network:

[0099] According to the modulation process when FBMC adopts a multi-phase network structure, the input-output function relationship expression of the FBMC subcarrier filter group is established:

[0100] y fbmc =f fbmc (s M ,g M ,w M )

[0101] Among them, s M represents the input signal bit matrix of the filter bank, g M represents the phase factor of the FBMC multiphase network, w M Represents the rotation factor of the inverse fast Fourier transform. The above functional relationship is matrixed to construct the product of the inverse fast Fourier transform matrix and the PPN (Polyphase network):

[0102] Y fbmc =S M ·G M ·W M

[0103] Then we obtain the polyphase network G of the FBMC subcarrier filter bank: M , M is the order of inverse fast Fourier transform.

[0104] (2) Extract the input-output relationship of the phased array multi-carrier filter group and construct the phased array multi-carrier filter network:

[0105] Settings multicarrier =[s 1 ,s 2 …sN ] T is the signal on N array elements, represents the amplitude and phase gain of the transmitted signal on N array elements. The input-output relationship of the phased array multi-carrier filter bank is expressed as:

[0106]

[0107] The above functional relationship is matrixed and constructed as the product of the data matrix, the filter network and the gain matrix:

[0108] V multicarrier =S multicarrier ·P multicarrier ·Φ multicarrier

[0109] Then we can obtain the phased array multi-carrier filter network P multicarrier .

[0110] (3) The polyphase network of the FBMC subcarrier filter bank and the beamforming network of the phased array multicarrier filter bank are cascaded through a weighted mapping relationship:

[0111] The signal is passed through the polyphase network G of the FBMC subcarrier filter bank. M By extending the network K ex Extension to Phased Array Multicarrier Filter Networks multicarrier , and use this to build a multi-phase cascade network Ω unite .

[0112] Ω unite =f unite (G M ,K ex ,P multicarrier )

[0113] Among them, f unite It represents the cascade relationship between the three. The specific implementation can be described as the signal passing through the FBMC multi-phase network, synthesizing into one signal, and then extending the network K ex , the synthesized signal is extended to N antenna elements, and the N signals are further processed by the phased array multi-carrier filter network and finally transmitted by the phased array antenna.

[0114] The design of the traditional FBMC subcarrier filter group is mainly based on the two principles of minimum out-of-band leakage power and filter sampling Nyquist criterion to optimize the filter width and overlap of the prototype filter group. It does not consider the associated control of a single FBMC carrier after the phased array antenna synthesizes multiple FBMC carriers, so that the interference between FBMC carriers cannot be reduced. At the same time, it only considers the channel as a Gaussian white noise channel, ignoring the fading of multi-signal transmission such as Doppler frequency deviation and large-scale path loss, which will not meet the optimization requirements of complex phased array low-orbit satellite channels. In addition, the single-channel signal after the optimization of the traditional FBMC subcarrier filter still needs to be merged with other multi-channel signals to form multiple carriers through the phased array antenna to form a space-division multiplexed synthetic carrier. Therefore, for the phased array, the optimization of carrier performance should be fully reflected in the out-of-band leakage suppression of each combined carrier by the filter group. The embodiment of this specification intends to use the multi-phase cascade network of the FBMC subcarrier filter group and the phased array multi-carrier filter group to extend the energy limit of the subcarrier to the energy limit between the phased array multi-carriers, and give full play to the optimization control ability of the FBMC filter on the phased array beam.

[0115] Step 106: Perform channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine a root mean square error of the low-orbit satellite channel.

[0116] In the specific implementation process, after constructing the low-orbit satellite channel response matrix and the multi-phase cascade network of subcarrier filters and phased array multi-carrier filters, the signal in the embodiment of this specification passes through the prototype filter, and then is processed by the subcarrier filter group, and then further processed by the phased array multi-carrier filter, and finally transmitted to the receiving end by the phased array. Based on this, the communication environment of the low-orbit satellite channel can be simulated, and the time domain equivalent superposition of the sampling scaled linear minimum mean square error channel estimation and the filter group can be completed. The linear minimum mean square error channel estimation time domain function after passing through the space-time non-stationary channel is related to the response after the filter time domain conversion through the time domain equivalent superposition method, which lays the foundation for the optimization design of the subsequent filter.

[0117] In some embodiments of the present specification, the performing channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine the root mean square error of the low-orbit satellite channel includes:

[0118] According to the demodulation process when FBMC adopts a multi-phase cascade network structure, a receiving end interpretation filter bank is established;

[0119] Using a sliding window to segment the output signal matrix of the interpretation filter bank, and performing channel estimation on the segmented signal sub-matrices respectively to obtain a channel estimation response matrix of each signal sub-matrix;

[0120] Merging the channel estimation response arrays of each signal sub-array to obtain a channel estimation result of the output result of the interpretation filter bank;

[0121] A root mean square error of the channel estimation is determined according to the channel estimation result and the channel estimation value of the target channel response.

[0122] In the specific implementation process, the embodiments of this specification can first construct an interpretation filter group that can be controlled according to channel changes at the receiving end, and then set a linear minimum root mean square error channel estimator with a sliding window and sliding step that can be dynamically adjusted, and complete the equivalent superposition through the joint MSE solution to obtain the root mean square error of the channel estimation. By combining the linear smoothing minimum root mean square error channel estimation model, the MSE of the channel estimation is minimized to meet the optimal control problem of out-of-band leakage constraints, effective reconstruction constraints, and signal response time and space variation range constraints. Figure 2 The specific process can be referred to as follows:

[0123] (1) The receiver constructs an interpretation filter bank that can be controlled according to channel changes

[0124] According to the demodulation process when FBMC adopts a multi-phase network structure, the input-output function relationship expression of the receiving end interpretation filter bank is established:

[0125]

[0126] Among them, r M represents the received signal matrix explaining the filter bank, represents the phase factor of the polyphase network explaining the filter, represents the fast Fourier transform rotation factor, Represents the output signal matrix of the interpretation filter. The above functional relationship is matrixed and constructed as the product of the fast Fourier transform matrix and the polyphase network:

[0127]

[0128] Then we get the FBMC interpretation filter bank M is the order of the fast Fourier transform.

[0129] (2) Set a linear minimum root mean square error channel estimator with a sliding window and dynamically adjustable sliding steps

[0130] Set the output signal matrix of the interpretation filter bank The dimension is K divi ×L divi , through the window matrix Λ and the sliding step matrix Γ Sliding partition into N non-overlapping divisub-matrices, each containing p i pilot symbol and q i Data symbols. Establish the functional relationship between the window matrix Λ, the sliding step matrix Γ and the signal sub-matrix:

[0131]

[0132] Among them, according to the different channel qualities, the window matrix Λ can dynamically adjust the window size, and the sliding step matrix Γ can dynamically adjust the step length to match the channel state. Perform LMMSE channel estimation respectively and calculate the channel estimation response matrix of each subarray:

[0133]

[0134] in, Represents a subarray The pilot symbols in Represents a subarray The data symbols in the channel estimation response matrix of each sub-array are combined to obtain the channel estimation result of the interpretation filter output signal:

[0135]

[0136] (3) Calculate the mean square error of the channel estimate

[0137] The channel estimation error is obtained by subtracting the ideal channel response from the channel estimation value after LMMSE: Furthermore, by calculating the channel estimation error vector Δ LMMSE The expectation of its conjugate transposed product gives the root mean square error of the channel estimate:

[0138]

[0139] Low-orbit satellite channels are more complex than terrestrial channels, including large-scale fading, cloud and rain fading, shadow fading, multipath fading, Doppler fading, etc. The performance gain of the signal waveform should ultimately be reflected in the signal reception performance, but the gain of channel coding should not be considered. In the embodiments of this specification, the prototype filter design of FBMC should be able to provide gain for channel estimation performance to a certain extent through a specific receiving channel estimation algorithm, thereby reducing the impact of the phased array low-orbit satellite channel on the transmission signal. Then, the joint design of phased array satellite channel estimation and FBMC prototype filter is realized to solve the receiving channel estimation performance of phased array low-orbit satellites.

[0140] Step 108: Based on the root mean square error, establish the objective function and constraint of the low-orbit satellite prototype filter.

[0141] In the specific implementation process, the objective function of optimizing the FBMC prototype filter under the satellite channel is established based on the root mean square error of the channel estimation obtained in the above embodiment, the constraint amount required for the perfect reconstruction of the FBMC prototype filter under the satellite channel is set, and the objective function and the constraint amount are combined to establish the FBMC optimization problem under the dynamic space-time non-stationary satellite channel. In some embodiments of this specification, the objective function can be the minimum MSE (mean square error) of the channel estimation, and the constraint conditions are to meet the out-of-band leakage constraint, the effective reconstruction constraint, the signal response time and space variation range constraint, etc.

[0142] In some embodiments of this specification, the objective function and constraint amount of the low-orbit satellite prototype filter are established based on the root mean square error, including:

[0143] The root mean square error is solved by using a minimum function to construct an objective function of the low-orbit satellite prototype filter;

[0144] Constructing a first constraint of the objective function based on the power spectrum and main lobe energy of the prototype filter;

[0145] A second constraint of the objective function is constructed based on the frequency response function of the prototype filter.

[0146] In the specific implementation process, Figure 2 As shown in the figure, the transmission reliability of the FBMC system under the dynamic space-time non-stationary satellite channel is taken as the primary consideration of the prototype filter optimization problem, and the MSE of the channel estimation of the FBMC system is minimized as the target optimization function. The MSE obtained by the above embodiment is calculated using the minimum function min(x). sat Solve it and then construct the objective function of the low-orbit satellite prototype filter:

[0147]

[0148] Set f dec ,f dec <f TH The sidelobe attenuation depth h of the normalized power spectrum of the FBMC prototype filter is sufficient dec (f dec ) when the bandwidth occupied, the decay rate is determined by f TH Limitation. The first constraint is to reduce the protection bandwidth in the satellite occupied frequency band, concentrate the prototype filter main lobe energy, and improve the satellite spectrum utilization rate:

[0149]

[0150] Among them, |G dec (f)| 2 is the power spectrum of the FBMC prototype filter, ETH is the main lobe energy. dec (f) The corresponding frequency response function of the FBMC prototype filter g dec (k) is set to a real symmetric form, and x is set to represent half of the coefficient vector to be solved. dec The energy of (k) is normalized:

[0151]

[0152] Then determine the second constraint of the objective function:

[0153] The objective function of minimizing the channel estimation MSE is combined with constraints such as attenuation depth, attenuation speed, real symmetric frequency response function, and energy normalization to establish the FBMC optimization problem under dynamic space-time non-stationary satellite channels:

[0154]

[0155] Step 110: Optimize the objective function according to the constraint amount to obtain coefficients of the prototype filter.

[0156] In the specific implementation process, the objective function is optimized and solved based on the constraints in the above embodiment, and then the coefficients of the prototype filter are determined. The optimization problem under the constraints can be converted into an unconstrained problem using the optimization function, and the unconstrained optimization problem is solved to obtain the filter coefficients. Figure 2 The specific process can be referred to as follows:

[0157] (1) Convert the optimization problem under constraints into an unconstrained problem using the optimization function

[0158] According to the objective optimization function J of the FBMC optimization problem under dynamic space-time non-stationary satellite channels 1 (x) and the constraint J 2 (x), J 3 (x) Establish the optimization function F(x,η), F(x,η) is determined by J 1 It consists of two parts: (x) and ηQ(x).

[0159] F(x,η)=J 1 (x)+ηQ(x)

[0160] Where η is the optimization factor, expressed as J 2 (x), ω is represented by J 3 (x), Q(x) is given by χ(J 2 (x)) and ω(J 3(x)). Assuming a≥1, b≥1, the function χ, ω is further expressed as χ=[max{0,-J 2 (x)}] a ,ω=|J 3 (x)| b .

[0161] Q(x)=χ(J 2 (x))+ω(J 3 (x)

[0162] (2) Solving unconstrained optimization problems

[0163] The main step in solving the unconstrained optimization problem is to take a monotonically increasing sequence {η k}, {η k} tends to infinity. From η 1 First, for any k, solve minF(x,η k ) thus obtaining a sequence of minimum points.

[0164] The specific implementation method is to give an initial point x (0) , initial optimization factor η 1 , amplification factor e>1, error factor ε>0, k=1. k-1 As the initial point, solve the unconstrained problem:

[0165] min 1 (x)+η k Q(x)

[0166] Set the minimum point to x (k) , when η k Q(x (k) )<ε, then stop the calculation and get x (k) , in other cases η k+1 =eη k , let k = k + 1, let x k-1 Repeat the above steps for the initial point to continue solving.

[0167] By repeatedly iterating and solving the minimum sequence of minF(x,η), the coefficients of the FBMC prototype filter under the dynamic space-time non-stationary satellite channel are obtained. The other half of the filter coefficients are further calculated according to the real symmetry characteristics of the prototype filter, and all the coefficients of the prototype filter for the low-orbit satellite channel are obtained.

[0168] In some embodiments of this specification, the method further includes:

[0169] The structural parameters of the prototype filter and the polyphase cascade network of the subcarrier filter group and the phased array multi-carrier filter group are determined based on the coefficients of the prototype filter.

[0170] In the specific implementation process, after determining the coefficients of the prototype filter, the obtained filter coefficients Substitute the prototype function g of the FBMC filter sat (t), and then the FBMC prototype filter can be reconstructed based on the coefficients of the prototype filter.

[0171] At the same time, after reconstructing the prototype filter, the multiphase network structure G of the FBMC transmitter integrated filter bank can be obtained through further frequency shifting. M , and the corresponding multi-phase network structure of the receiver interpretation filter bank This then enables the joint design of the prototype filter and the phased array beamforming network.

[0172] The embodiment of this specification provides a design method for a prototype filter of a low-orbit satellite. The low-orbit satellite channel is more complex than the ground channel, including large-scale fading, cloud and rain fading, shadow fading, multipath fading, Doppler fading, etc. The performance gain of the signal waveform should ultimately be reflected in the signal reception performance. In the receiving model, the processing of the signal by the channel estimation includes the adaptation processing of the prototype filter response. Therefore, by further optimizing the design of the prototype filter, the reception channel estimation performance of the phased array low-orbit satellite can be further improved. By constructing the multiphase decomposition function of the channel model of the phased array low-orbit satellite Internet, the dynamic space-time non-stationary satellite channel response matrix is ​​obtained, and then the linear smoothing minimum root mean square error channel estimation model is combined to construct the channel estimation with the minimum MSE, satisfying the optimal control problem of out-of-band leakage constraint, effective reconstruction constraint, signal response space-time variation range constraint, etc. Finally, by solving the optimization problem, the satellite FBMC prototype filter design strategy that satisfies the perfect reconstruction under the space-time non-stationary satellite channel is obtained, and the reception channel estimation performance of the FBMC system under the condition of the phased array low-orbit satellite is improved.

[0173] Based on the design method of the low-orbit satellite prototype filter described above, one or more embodiments of this specification also provide a device for designing a low-orbit satellite prototype filter. The device may include a device (including a distributed system), software (application), module, component, server, client, etc. using the method described in the embodiments of this specification and a device combined with necessary implementation hardware. Based on the same innovative concept, the device in one or more embodiments provided in the embodiments of this specification is as described in the following embodiments. Since the implementation scheme and method of the device to solve the problem are similar, the implementation of the specific device in the embodiments of this specification can refer to the implementation of the aforementioned method, and the repetitions will not be repeated. As used below, the term "unit" or "module" can be a combination of software and / or hardware that implements predetermined functions. Although the device described in the following embodiments is preferably implemented in software, the implementation of hardware, or a combination of software and hardware, is also possible and conceived.

[0174] Specifically, Figure 3 : is a schematic diagram of the module structure of an embodiment of a design device for a prototype filter of a low-orbit satellite provided in this specification, such as Figure 3 As shown, the device provided in this specification may include:

[0175] A response matrix construction module 31 is used to construct a dynamic space-time non-stationary phased array low-orbit satellite channel response matrix;

[0176] A cascade network construction module 32, used to design a polyphase cascade network of a subcarrier filter bank and a phased array multi-carrier filter bank;

[0177] A channel estimation module 33, configured to perform channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network, and determine a root mean square error of the low-orbit satellite channel;

[0178] An objective function building module 34 is used to establish an objective function and a constraint amount of a low-orbit satellite prototype filter based on the root mean square error;

[0179] The filter coefficient determination module 35 is used to optimize the objective function according to the constraint amount to obtain the coefficients of the prototype filter.

[0180] Figure 4 FIG. 1 is a schematic diagram of a module structure of another embodiment of a design device for a prototype filter for a low-orbit satellite provided in this specification. Figure 4 As shown, in some embodiments of the present specification, the device also includes a filter and cascade network design module 41, which is used to determine the structural parameters of the prototype filter and the multi-phase cascade network of the subcarrier filter group and the phased array multi-carrier filter group based on the coefficients of the prototype filter.

[0181] It should be noted that the above-mentioned device may also include other implementations according to the description of the method embodiment. The specific implementation methods can refer to the description of the relevant method embodiment, and will not be described one by one here.

[0182] The method embodiments provided in the embodiments of this specification can be executed in a mobile terminal, a computer terminal, a server or a similar computing device. Taking running on a server as an example, Figure 5 1 is a hardware structure block diagram of a design server of a low-orbit satellite prototype filter in one embodiment of this specification. The computer terminal may be a design server of a low-orbit satellite prototype filter in the above embodiment and a design device of a low-orbit satellite prototype filter. Figure 5 The server 10 shown may include one or more (only one is shown in the figure) processors 100 (the processor 100 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA), a non-volatile memory 200 for storing data, and a transmission module 300 for communication functions. Those skilled in the art will understand that Figure 5 The structure shown is only for illustration and does not limit the structure of the above electronic device. Figure 5 More or fewer components shown in the figure may also include other processing hardware, such as a database or multi-level cache, GPU, or other hardware with Figure 5 Different configurations shown.

[0183] The non-volatile memory 200 can be used to store software programs and modules of application software, such as the program instructions / modules corresponding to the design method of the prototype filter of the low-orbit satellite in the embodiment of this specification. The processor 100 executes various functional applications and resource data updates by running the software programs and modules stored in the non-volatile memory 200. The non-volatile memory 200 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the non-volatile memory 200 may further include a memory remotely arranged relative to the processor 100, and these remote memories may be connected to the computer terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0184] The transmission module 300 is used to receive or send data via a network. The specific example of the above network may include a wireless network provided by a communication provider of a computer terminal. In one example, the transmission module 300 includes a network adapter (Network Interface Controller, NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission module 300 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0185] Corresponding to the above method, the present invention also provides an apparatus, which includes a computer device, the computer device includes a processor and a memory, the memory stores computer instructions, the processor is used to execute the computer instructions stored in the memory, and when the computer instructions are executed by the processor, the apparatus implements the steps of the method described above.

[0186] The embodiment of the present invention also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, the steps of the aforementioned edge computing server deployment method are implemented. The computer-readable storage medium can be a tangible storage medium, such as a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a floppy disk, a hard disk, a removable storage disk, a CD-ROM, or any other form of storage medium known in the technical field.

[0187] It should be understood by those skilled in the art that the exemplary components, systems and methods described in conjunction with the embodiments disclosed herein can be implemented in hardware, software or a combination of the two. Whether it is performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in, a function card, etc. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link via a data signal carried in a carrier.

[0188] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0189] In the present invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with features of other embodiments or replace features of other embodiments.

[0190] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the embodiments of the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A design method for a prototype filter of a low-orbit satellite, characterized in that: The method comprises the following steps: Construct the channel response matrix of dynamic space-time non-stationary phased array low-orbit satellite; Design polyphase cascade networks of subcarrier filter banks and phased array multicarrier filter banks; Performing channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine a root mean square error of the low-orbit satellite channel; Based on the root mean square error, an objective function and a constraint amount of a low-orbit satellite prototype filter are established; According to the constraint amount, the objective function is optimized to obtain coefficients of the prototype filter; The design of a multi-phase cascade network of a subcarrier filter group and a phased array multicarrier filter group includes: Extract the input-output relationship of the FBMC subcarrier filter bank and construct a subcarrier filter bank multiphase network; Extract the input-output relationship of the phased array multi-carrier filter group and construct the phased array multi-carrier filter network; Cascading the subcarrier group multi-phase network and the phased array multi-carrier filter network through a weighted mapping relationship to obtain the multi-phase cascade network; The performing channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine the root mean square error of the low-orbit satellite channel includes: According to the demodulation process when FBMC adopts a multi-phase cascade network structure, a receiving end interpretation filter bank is established; Using a sliding window to segment the output signal matrix of the interpretation filter bank, and performing channel estimation on the segmented signal sub-matrices respectively to obtain a channel estimation response matrix of each signal sub-matrix; Merging the channel estimation response matrices of the signal sub-arrays to obtain a channel estimation result of the output result of the interpretation filter bank; A root mean square error of the channel estimation is determined according to the channel estimation result and the channel estimation value of the target channel response.

2. The method according to claim 1, characterized in that The constructing of a dynamic space-time non-stationary phased array low-orbit satellite channel response matrix comprises: Construct a normalized correlation model of multi-level channel fading and the behavioral response of LEO satellite phased arrays to multi-carrier signals; The normalized correlation model is combined with the behavioral response to obtain the dynamic space-time non-stationary phased array low-orbit satellite channel response matrix.

3. The method according to claim 1, characterized in that The objective function and constraint amount of the low-orbit satellite prototype filter are established based on the root mean square error, including: The root mean square error is solved by using a minimum function to construct an objective function of the low-orbit satellite prototype filter; Constructing a first constraint of the objective function based on the power spectrum and main lobe energy of the prototype filter; A second constraint of the objective function is constructed based on the frequency response function of the prototype filter.

4. The method according to claim 1, characterized in that The method further comprises: The structural parameters of the prototype filter and the polyphase cascade network of the subcarrier filter group and the phased array multi-carrier filter group are determined based on the coefficients of the prototype filter.

5. A design device for a prototype filter of a low-orbit satellite, characterized in that: The device includes: The response matrix construction module is used to construct the channel response matrix of the dynamic space-time non-stationary phased array low-orbit satellite; A cascade network construction module is used to design a multi-phase cascade network of a subcarrier filter group and a phased array multicarrier filter group; the design of the multi-phase cascade network of the subcarrier filter group and the phased array multicarrier filter group includes: extracting the input-output relationship of the FBMC subcarrier filter group to construct a subcarrier device group multi-phase network; extracting the input-output relationship of the phased array multicarrier filter group to construct a phased array multicarrier filter network; cascading the subcarrier device group multi-phase network and the phased array multicarrier filter network through a weighted mapping relationship to obtain the multi-phase cascade network; A channel estimation module, used to perform channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine the root mean square error of the low-orbit satellite channel; the channel estimation based on the low-orbit satellite channel response matrix and the multi-phase cascade network to determine the root mean square error of the low-orbit satellite channel includes: establishing a receiving end interpretation filter group according to the demodulation process when FBMC adopts a multi-phase cascade network structure; using a sliding window to divide the output signal matrix of the interpretation filter group, and performing channel estimation on the divided signal sub-arrays respectively to obtain the channel estimation response matrix of each signal sub-array; merging the channel estimation response matrices of each signal sub-array to obtain the channel estimation result of the output result of the interpretation filter group; determining the root mean square error of the channel estimation according to the channel estimation result and the channel estimation value of the target channel response; An objective function building module is used to establish an objective function and a constraint of a low-orbit satellite prototype filter based on the root mean square error; The filter coefficient determination module is used to optimize the objective function according to the constraint amount to obtain the coefficients of the prototype filter.

6. The device according to claim 5, characterized in that The device also includes a filter and cascade network design module, which is used to determine the structural parameters of the prototype filter and the multi-phase cascade network of the subcarrier filter group and the phased array multi-carrier filter group based on the coefficients of the prototype filter.

7. A design device for a prototype filter of a low-orbit satellite, comprising a processor and a memory, characterized in that: The memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor, the device implements the steps of the method according to any one of claims 1 to 4.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 4 are implemented.

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