Space-ground integrated anti-jamming method and system based on multi-satellite cooperation

Abstract

The application relates to the technical field of satellite communication, and particularly discloses a space-ground integrated anti-interference method and system based on multi-satellite cooperation, which comprises the following steps: S1, a ground station sends a communication signal, and an interference station sends an interference signal; S2, a cooperative satellite and a communication satellite simultaneously receive the communication signal and the interference signal, obtain a disturbed signal, and transmit the disturbed signal to a receiving ground station; S3, the receiving ground station performs Taylor series expansion on a delayed communication signal, separates a delay difference of the disturbed signal from a signal waveform, and obtains a disturbed signal of a single satellite after eliminating the delay difference and a disturbed total signal of all satellites; S4, the receiving ground station performs whitening processing on the disturbed total signal, and obtains a whitened signal; and S5, the receiving ground station rotates the whitened signal, extracts an estimated spread signal vector from the whitened signal, and identifies an estimated communication signal. The application effectively suppresses strong external interference and realizes a method and system for reliably recovering a communication signal.

Description

Technical Field

[0001] This invention relates to the field of satellite communication technology, and specifically to a ground-to-ground integrated anti-interference method and system based on multi-satellite collaboration. Background Technology

[0002] As an important supplement to terrestrial networks, satellite communication's open channels are susceptible to interference from complex electromagnetic environments. Traditional anti-jamming technologies, such as spread spectrum communication, suffer from performance degradation under specific interference patterns and have low spectral efficiency; increasing transmission power is limited by the satellite system's energy consumption; and onboard adaptive nulling antennas have insufficient ability to suppress main lobe interference.

[0003] Multi-satellite cooperative technology, which enhances anti-jamming capabilities through spatial diversity, has become a research hotspot. Existing methods focus on resource allocation optimization, cooperative beamforming, and distributed precoding design, but generally overlook a key bottleneck—the signal propagation delay difference (PDD) caused by multi-satellite relays. The large spatial scale (geocene angle 2°–10°) between geostationary orbit satellites leads to significant differences in signal propagation paths. Simulations show that when the ground jamming station is 300km away from the transmitting station, the maximum PDD can reach 1.4 × 10⁻⁶. -4 Seconds, compared to the typical low-speed service symbol period (e.g., 2.08 × 10⁻⁶ for 1.2 kbps voice). -4 The delay difference is equivalent to a second. This delay difference causes severe asynchrony in the communication signals received by the ground station, which not only introduces inter-symbol interference but also completely disables the cooperative reception algorithm that relies on the signal synchronization assumption. Existing literature either avoids this problem or only addresses frequency offset compensation for low-Earth orbit satellites, lacking an effective solution for signal asynchrony caused by large-scale PDD of multiple GEO satellites, which seriously restricts the anti-interference performance of the integrated space-ground cooperative system.

[0004] The closest existing technical solutions focus on multi-satellite collaborative anti-interference, all of which assume satellite-to-ground link signal synchronization or only compensate for frequency domain deviations. They cannot solve the symbol-level asynchrony problem caused by path length differences, resulting in severe degradation of interference suppression performance in practical applications.

[0005] The existing technologies have the following main drawbacks: 1) Ignoring the impact of propagation delay difference: Current multi-satellite cooperative anti-interference schemes generally assume that the satellite-to-ground link signals are synchronized, or only compensate for the Doppler frequency offset of low-orbit satellites, without addressing the significant propagation delay difference (PDD) between geostationary orbit (GEO) satellites caused by large spatial scales (geocene angle 2°–10°); 2) Failure of asynchronous signal processing: The delay difference causes symbol-level asynchrony in the multiple communication signals received by the ground station, which introduces inter-symbol interference (ISI) and undermines the signal synchronization premise on which traditional cooperative reception algorithms rely, resulting in severe degradation or even complete failure of interference suppression performance; 3. Limitations of on-board processing: The on-board platform is difficult to handle the complex calculations required for high-precision signal alignment, while direct processing of asynchronous signals on the ground will exacerbate the bit error rate. Summary of the Invention

[0006] To address the aforementioned problems, the purpose of this invention is to provide a multi-satellite collaborative space-ground integrated anti-interference method and system that overcomes the significant propagation delay difference caused by the differences in the propagation paths of signals from different satellite-to-ground links, thereby effectively suppressing strong external interference and achieving reliable communication signal recovery.

[0007] This invention provides a space-ground integrated anti-interference method based on multi-satellite collaboration, comprising: Step S1: The ground station sends communication signals to the cooperating satellite and the communication satellite, and the jamming station sends jamming signals to the cooperating satellite and the communication satellite. In step S2, the cooperating satellite and the communication satellite simultaneously receive the communication signal and the interference signal, obtain the interfered signal, and transmit the interfered signal to the receiving ground station; Step S3: The receiving ground station uses the propagation path of the satellite with the median delay difference among multiple satellites as the time reference, performs Taylor series expansion on the delayed communication signal, separates the delay difference of the disturbed signal from the signal waveform, and obtains the disturbed signal of a single satellite with the delay difference eliminated and the total disturbed signal of all satellites with the delay difference eliminated. Step S4: The receiving ground station performs whitening processing on the disturbed total signal to obtain a whitened signal; In step S5, the receiving ground station rotates the whitened signal, extracts the estimated extended signal vector from the whitened signal, and identifies the estimated communication signal in the estimated extended signal vector to achieve interference suppression.

[0008] In one possible implementation, step S2 includes: The following formula represents the number received by the ground station. Disturbed signals from individual satellites : ; In the formula, For communication signals, For interference signals, For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For communication signals via the first Total propagation delay of uplink and downlink relayed by each satellite For interference signals via the first Total propagation delay of uplink and downlink relayed by each satellite To receive the first... Total noise of uplink and downlink for each satellite For time.

[0009] In one possible implementation, step S3 includes: The following formula represents the number received by the ground station. The communication signals transmitted by the first satellite are compared to those of the second. The time difference of communication signals transmitted by each satellite : ; In the formula, The communication signal transmitted by the s-th satellite compared to the s-th satellite The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The time difference of communication signals transmitted by each satellite.

[0010] In one possible implementation, step S3 further includes: The Taylor series of a delayed communication signal can be expressed by the following formula. : ; In the formula, For residual error, For communication signals First derivative, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For the residual error term in the Taylor series expansion, For time; Substituting the Taylor series into the disturbed signal yields the disturbed signal of a single satellite with the delay difference eliminated. The formula is as follows: ; In the formula, For the first Error terms of each satellite For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For communication signals, For interference signals, For communication signals First derivative, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For time.

[0011] In one possible implementation, step S3 further includes: The total interference signal received by the ground station from all satellites is expressed by the following formula. : ; In the formula, To extend signal vector, To expand the channel matrix, For error terms, For time.

[0012] In one possible implementation, step S3 further includes: The extended signal vector is represented by the following formula. : ; in For communication signals, For communication signals First derivative, For interference signals, For transpose, For time.

[0013] In one possible implementation, step S4 includes: The whitening signal is represented by the following formula. : ; In the formula, To receive the total interference signals from all satellites received by the ground station; The whitening matrix is ​​expressed by the following formula. : ; In the formula, Covariances arranged in descending order Eigenvalues Eigenvalues Corresponding feature vectors , is the index of the eigenvalue.

[0014] In one possible implementation, step S5 includes: The estimated extended signal vector is extracted from the whitened signal according to the following formula. : ; In the formula, For whitening signal, For whitening matrix, To expand the channel matrix; The extended channel matrix is ​​expressed by the following formula. : ; In the formula, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, The number of cooperating satellites.

[0015] In one possible implementation, step S5 further includes: The two signals representing the estimated communication signal and the first derivative of the estimated communication signal in the extended signal vector are determined based on the covariance matrix of the extended signal vector. The signal with the lower average frequency among the two signals is identified as the estimated communication signal; The covariance matrix of the extended signal vector can be expressed by the following formula. : ; In the formula, For communication signals autocorrelation function For communication signals First derivative of communication signal cross-correlation function The first derivative of the communication signal and communication signals cross-correlation function The autocorrelation function of the first derivative of the communication signal. Interference signal The covariance matrix.

[0016] This invention also provides a multi-satellite collaborative space-ground integrated anti-interference system, applied to any of the aforementioned space-ground integrated anti-interference methods, comprising: The ground station is used to send communication signals to cooperating and communication satellites; Jamming stations are used to send jamming signals to cooperative and communication satellites. The cooperative satellite and communication satellite are used to simultaneously receive the communication signal and the interference signal, obtain the interfered signal, and transmit the interfered signal to the receiving ground station; The receiving ground station is used to perform Taylor series expansion on the delayed communication signal using the propagation path of the satellite with the median delay difference among multiple satellites as the time reference, to separate the delay difference of the disturbed signal from the signal waveform, and to obtain the disturbed signal of a single satellite with the delay difference eliminated and the total disturbed signal of all satellites with the delay difference eliminated. The receiving ground station is also used to whiten the disturbed total signal to obtain a whitened signal; The receiving ground station is also used to rotate the whitened signal, extract the estimated extended signal vector from the whitened signal, and identify the estimated communication signal in the estimated extended signal vector to achieve interference suppression.

[0017] The multi-satellite collaborative anti-interference method and system provided by this invention overcomes the symbol-level asynchrony problem caused by the difference in propagation paths of different satellite-to-ground links in a multi-GEO satellite and ground station collaborative anti-interference system, eliminates the inter-symbol interference and interference suppression failure caused by this, and achieves robust recovery of communication signals under strong interference environment. Attached Figure Description

[0018] Figure 1 A schematic flowchart of the integrated air-ground anti-interference method provided for embodiments of the present invention; Figure 2 A schematic diagram of the integrated air-ground anti-interference system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram showing the location of the communication and jamming terminals provided in an embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the maximum delay difference corresponding to different numbers of cooperating satellites, as provided in an embodiment of the present invention. Figure 5 This is a schematic diagram illustrating the impact of different numbers of cooperating satellites on algorithm performance, provided in an embodiment of the present invention. Figure 6 This is a schematic diagram illustrating the impact of different signal-to-noise ratios on the error rate performance of the algorithm, provided in an embodiment of the present invention. Figure 7 This is a schematic diagram illustrating the impact of different interference-to-signal ratios on the system bit error rate, provided in an embodiment of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. That is, the present invention is not limited to the described preferred embodiments, and the scope of the present invention is defined by the claims.

[0020] In the description of this invention, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance; those skilled in the art can understand the specific meaning of the above terms in this invention as appropriate.

[0021] Because uplink interference has a significant impact on satellite communication systems, this invention considers multi-satellite joint interference suppression during uplink interference. This invention considers N cooperating GEO satellites, one transmitting ground station, one receiving ground station, and one interference station. Each satellite is equipped with an adaptive nulling antenna for initial suppression of interference signals, and each ground station is equipped with a single antenna. The system structure is as follows: Figure 2 As shown.

[0022] Figure 1 A schematic flowchart of the integrated air-ground anti-interference method provided in the embodiments of the present invention is shown below. Figure 1 As shown, this invention provides a space-ground integrated anti-interference method based on multi-satellite collaboration, comprising: Step S1: The ground station sends communication signals to the cooperating satellite and the communication satellite, and the jamming station sends jamming signals to the cooperating satellite and the communication satellite. In step S2, the cooperating satellite and the communication satellite simultaneously receive the communication signal and the interference signal, obtain the interfered signal, and transmit the interfered signal to the receiving ground station; In one possible implementation, the communication satellite and the cooperating satellite use an adaptive nulling antenna to receive the disturbed signal, suppress some of the interference, and transmit the disturbed signal to the receiving ground station for processing via a broadband high-speed downlink. That is, baseband airspace signal processing is performed at the receiving ground station to suppress interference.

[0023] The following formula represents the number received by the ground station. The actual interference signal of each satellite : ; Because the interference signal power is relatively high in each received signal, it is easy to align the waveform of the disturbed signal. At this time, the ground station receives the... The actual interference signal transmitted by each satellite Equivalent to the disturbed signal below .

[0024] The following formula represents the number received by the ground station. Disturbed signals from individual satellites : ; In the formula, For communication signals, For interference signals, For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For communication signals via the first Total propagation delay of uplink and downlink relayed by each satellite For interference signals via the first Total propagation delay of uplink and downlink relayed by each satellite To receive the first... Total noise of uplink and downlink for each satellite For time.

[0025] Step S3: The receiving ground station uses the propagation path of the satellite with the median delay difference among multiple satellites as the time reference, performs Taylor series expansion on the delayed communication signal, separates the delay difference of the disturbed signal from the signal waveform, and obtains the disturbed signal of a single satellite with the delay difference eliminated and the total disturbed signal of all satellites with the delay difference eliminated. In one possible implementation, the receiving ground station receives the first... The communication signals transmitted by the first satellite are compared to those of the second. The time difference of communication signals transmitted by each satellite : ; In the formula, The communication signal transmitted by the s-th satellite compared to the s-th satellite The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The time difference of communication signals transmitted by each satellite.

[0026] As can be seen from the above formula, the delay difference of communication signals relayed by different satellites is not only related to the propagation delay of the communication signals, but also to the propagation delay of the interference signals.

[0027] Figure 3 This is a schematic diagram of the location of communication and jamming terminals provided in an embodiment of the present invention, as shown below. Figure 3 As shown, the first in the air The satellite is A, number The satellite is designated B, the transmitting ground station is C, the receiving ground station is O, and the interfering station is E. Ignoring on-board signal processing delays, the delay difference is expressed by the following formula: ; Therefore, the time delay difference of communication signals passing through different satellites is expressed by the following formula: ; In the formula, c is the speed of light.

[0028] As can be seen from the above formula, the time difference of communication signals relayed by different satellites is independent of the location of the receiving station.

[0029] The analysis process is illustrated using the following conditions as an example. Assume that the transmitting ground station C is located at the sub-satellite point of satellite A, and the interfering station E is located on the equator. Both C and E are within the coverage area of ​​the satellite's main lobe beam, meaning the distance between C and E is... , It is the width of the overlapping coverage area of ​​each cooperating satellite beam.

[0030] ; Case 1: When B and E are on the same side of AC, ; Case 2: When B and E are on different sides of AC, ; In the formula, R is the Earth's radius, L is the altitude of the geostationary orbit, It is the geocentric angle between satellites A and B. It is the geocentric angle between the jamming station E and the ground transmitting station C.

[0031] ; The ITU specifies that the minimum geocentric angle between adjacent geostationary orbits is 2 degrees. If four satellites are used for cooperative reception, the geocentric angle between any two cooperating satellites can be set between 2° and 10°. The main satellite uses a spot beam operating mode, assuming a beam coverage range of 300~700km, meaning the maximum distance between the jamming station and the ground transmitting station is 300~700km.

[0032] Under different interference distances and geocentric angles of cooperating satellites, the maximum propagation delay difference of communication signals across different satellites is approximately 1.4 × 10⁻⁴ seconds, and the maximum propagation delay is roughly equal in both cases. These two scenarios will not be discussed separately in subsequent studies. A common coding and modulation scheme in satellite transmission systems is the combination of 1 / 4-bit LDPC code and BPSK modulation to transmit voice services at information rates of 1.2 kbps and 2.4 kbps, with symbol periods of approximately 2.08 × 10⁻⁴ seconds and 1.04 × 10⁻⁴ seconds, respectively. It can be seen that the maximum propagation delay difference is comparable to the symbol period of the communication signal. In this case, because it is difficult to achieve time alignment between communication signals received by different satellites, the communication signal is not only subject to external interference but also suffers from severe inter-symbol interference, a problem that existing multi-satellite cooperative interference suppression methods have not considered.

[0033] In one possible implementation, since the maximum delay difference of the communication signal is comparable to the symbol period, this invention considers performing a Taylor series expansion on the delayed signal using the propagation path of the satellite with the median delay difference as the time reference, thus separating the signal propagation delay difference from the signal waveform to solve the communication signal alignment problem. Assume the... The number of cooperating satellites is the median of the time delay difference. The following formula represents the number of satellites with the highest time delay. Taylor series of satellite-delayed communication signals : ; In the formula, For residual error, For communication signals First derivative, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For the residual error term in the Taylor series expansion, For time; residual error and delay difference Related. Generally speaking, With delay It decreases as it decreases.

[0034] Substitute the Taylor series into the disturbed signal Obtain the disturbed signal from a single satellite after eliminating the time delay difference. The formula is as follows: ; In the formula, For the first Error terms for each satellite, , For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For communication signals, For interference signals, For communication signals First derivative, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For time.

[0035] In one possible implementation, the total interference signal received by the ground station from all satellites is represented by the following formula. : ; In the formula, To extend signal vector, To expand the channel matrix, For error terms, , For time.

[0036] The extended signal vector is represented by the following formula. : ; in For communication signals, For communication signals First derivative, For interference signals, For transpose, For time.

[0037] From the disturbed total signal As can be seen, the delay difference is extracted into the extended channel matrix. In this array, the random delay problem of multiple disturbed signals is eliminated.

[0038] Step S4: The receiving ground station performs whitening processing on the disturbed total signal to obtain the whitened signal; In one possible implementation, the total disturbed signal In addition to communication signals and interference signals, there also exists a first derivative of the communication signal. Therefore, when Time-spreading channel matrix Full rank allows for interference suppression by inversely recovering the communication signal from the extended channel matrix. Interference suppression can be achieved in two steps: whitening and rotation. Whitening involves using a matrix to process the received signal vector, making the received signals uncorrelated and normalizing the power of each received signal. If... Another function of it is to achieve dimensionality reduction. Rotation is used to recover and estimate the communication signal from the whitened received signal.

[0039] The whitening signal is represented by the following formula. : ; In the formula, To receive the total interference signals from all satellites received by the ground station; The whitening matrix is ​​expressed by the following formula. : ; In the formula, Covariances arranged in descending order Eigenvalues Eigenvalues Corresponding feature vectors , is the index of the eigenvalue.

[0040] In one possible implementation, the whitening matrix This can be determined by the following steps: The covariance matrix of the disturbed total signal vector can be expressed by the following formula. : ; In the formula, For expectation operation, For Dirichlet function, For noise variance, For time, For identity matrix, total disturbed signal Delayed total disturbance signal , For transpose, To expand the channel matrix.

[0041] The extended signal vector is represented by the following formula. covariance matrix : ; In the formula, For communication signals autocorrelation function For communication signals First derivative of communication signal cross-correlation function The first derivative of the communication signal and communication signals cross-correlation function The first derivative of the communication signal autocorrelation function Interference signal covariance matrix For communication signals Interference signals cross-correlation function The first derivative of the communication signal Interference signals cross-correlation function For interference signals and communication signals cross-correlation function Interference signal First derivative of communication signal The cross-correlation function.

[0042] Considering that the correlation function has the following properties: ; In the formula, For communication signals of Derivative and Cross-correlation function of second derivatives For communication signals exist Moment First derivative, For communication signals exist Moment First derivative, For communication signals of The autocorrelation function of the first derivative, and is the order of the derivative.

[0043] but: ; In the formula, .

[0044] therefore, It is a diagonalized matrix.

[0045] when hour, ; Whitening matrix and noise variance It can be derived from the covariance matrix Obtained by eigenvalue decomposition.

[0046] Noise variance estimation can be achieved by adjusting the covariance matrix. of The noise variance is obtained by averaging the lowest eigenvalues, and expressed by the following formula. : ; In the formula, Covariances arranged in descending order Eigenvalues.

[0047] Step S5: The receiving ground station rotates the whitened signal, extracts the estimated extended signal vector from the whitened signal, and identifies the estimated communication signal in the estimated extended signal vector to achieve interference suppression.

[0048] In one possible implementation, step S5 includes: The estimated extended signal vector is extracted from the whitened signal according to the following formula. : ; In the formula, For whitening signal, For whitening matrix, To expand the channel matrix; The extended channel matrix is ​​expressed by the following formula. : ; In the formula, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, The number of cooperating satellites.

[0049] In one possible implementation, the two signals representing the estimated communication signal and the first derivative of the estimated communication signal in the extended signal vector are determined based on the covariance matrix of the extended signal vector. The signal with the lower average frequency among the two signals is identified as the estimated communication signal.

[0050] This invention also provides a multi-satellite collaborative space-ground integrated anti-interference system, applicable to any of the above-mentioned space-ground integrated anti-interference methods, comprising: The ground station is used to send communication signals to cooperating and communication satellites; Jamming stations are used to send jamming signals to cooperative and communication satellites. Cooperative satellites and communication satellites are used to simultaneously receive communication signals and interference signals, obtain the interfered signal, and transmit the interfered signal to the receiving ground station; The receiving ground station is used to perform Taylor series expansion on the delayed communication signal based on the propagation path of the satellite with the median delay difference among multiple satellites. This separates the delay difference of the disturbed signal from the signal waveform, resulting in the disturbed signal of a single satellite with the delay difference eliminated and the total disturbed signal of all satellites with the delay difference eliminated. The receiving ground station is also used to whiten the disturbed total signal to obtain a whitened signal; The receiving ground station is also used to rotate the whitened signal, extract the estimated extended signal vector from the whitened signal, and identify the estimated communication signal in the estimated extended signal vector to achieve interference suppression.

[0051] The present invention will be further explained and illustrated below with reference to examples.

[0052] The number of cooperating satellites is distributed on both sides of satellite A, with a geocentric angle of 2° between adjacent cooperating satellites and a beam coverage radius of 300 km (i.e., the jamming station is 300 km from the ground transmitting station). The modulation method is BPSK, and the information rate is 9.6 kbps. The interference is multi-tone interference, with baseband interference frequencies of 400 Hz, 900 Hz, and 1.5 kHz. There are 5 joint diagonalized covariance matrices. The simulation results are the statistical mean of 3000 independent simulations, with the channel transmission coefficients in each simulation being randomly generated.

[0053] Figure 4 The maximum delay difference corresponding to different numbers of cooperating satellites is given. Under the conditions of a signal-to-noise ratio of 20dB and an interference-to-signal ratio of 40dB, using 3 cooperating satellites, the communication signal waveform after interference suppression using the algorithm of this invention is compared with the transmitted signal waveform. The algorithm of this invention can suppress interference and eliminate signal delay very well.

[0054] Figure 5The impact of the number of cooperating satellites on the algorithm of this invention was simulated at signal-to-noise ratios of 5dB, 10dB, and interference-to-signal ratio of 40dB. It can be seen that when the number of cooperating satellites is less than 6, the system bit error rate decreases as the number of cooperating satellites increases; when the number of cooperating satellites is more than 6, the system bit error rate tends to stabilize and no longer decreases with increasing number of cooperating satellites. Therefore, from the perspective of control system implementation complexity, more cooperating satellites are not necessarily better. Of course, the specific number of cooperating satellites should be determined based on the satellite distribution and the positions of the communicating sender and the interfering party. Under the conditions of this simulation, a number of cooperating satellites of 5 or less can achieve good interference suppression.

[0055] Figure 6 , Figure 7 The effects of different signal-to-noise ratios (SNRs) and different interference-to-signal ratios (ISRs) on the algorithm of this invention were simulated. Figure 6 As can be seen, the system bit error rate decreases with increasing signal-to-noise ratio, and the system bit error rate curves become quite similar after the number of cooperating satellites exceeds 6. Figure 7 Two conclusions can be drawn from this study. First, the bit error rate (BER) decreases as the interference-to-signal ratio (ISR) increases. This means that the method proposed in this invention has a better ability to suppress strong interference than weak interference. This is mainly because the larger the ISR, the greater the difference between the communication signal and the interference signal, and the better the non-singularity of equation (0.9) after normalizing the source signal energy, resulting in a more accurate estimation of the global matrix. Second, the BER tends to stabilize after the ISR increases to a certain value. This is mainly because when the signal difference becomes large enough, the extraction accuracy of the communication signal tends to stabilize. At this point, the interference has a smaller impact on the communication signal, and the key factor affecting the BER is the noise in the system.

[0056] This invention provides a multi-satellite collaborative integrated space-ground anti-interference method and system. By converting the asynchronous mixed signals generated by the large-scale propagation delay difference caused by multi-satellite collaboration into an equivalent synchronous linear mixed model using Taylor series expansion and joint matrix diagonalization techniques, it effectively separates and suppresses strong external interference signals, restoring clean communication signals. This method can be applied to integrated space-ground satellite communication systems based on the collaborative operation of multiple geostationary orbit (GEO) satellites and ground stations, especially in complex electromagnetic interference environments with significant path delay differences. This invention possesses superior real-time processing capabilities and computational efficiency (avoiding complex iterative optimization processes), providing highly reliable and robust anti-interference capabilities for satellite communication links facing strong interference (especially in scenarios with high interference-to-signal ratios, JSRs). Simultaneously, this technology provides a new and effective technical path for solving the signal asynchrony problem in large-scale space diversity receiving systems and achieving centralized and efficient interference suppression at ground stations under a transparent relay satellite system. It has significant application value for improving the survivability and reliability of satellite communication systems in harsh electromagnetic environments in the future.

[0057] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A space-ground integrated anti-interference method based on multi-satellite collaboration, characterized in that, include: Step S1: The ground station sends communication signals to the cooperating satellite and the communication satellite, and the jamming station sends jamming signals to the cooperating satellite and the communication satellite. In step S2, the cooperating satellite and the communication satellite simultaneously receive the communication signal and the interference signal, obtain the interfered signal, and transmit the interfered signal to the receiving ground station; Step S3: The receiving ground station uses the propagation path of the satellite with the median delay difference among multiple satellites as the time reference, performs Taylor series expansion on the delayed communication signal, separates the delay difference of the disturbed signal from the signal waveform, and obtains the disturbed signal of a single satellite with the delay difference eliminated and the total disturbed signal of all satellites with the delay difference eliminated. Step S4: The receiving ground station performs whitening processing on the disturbed total signal to obtain a whitened signal; In step S5, the receiving ground station rotates the whitened signal, extracts the estimated extended signal vector from the whitened signal, and identifies the estimated communication signal in the estimated extended signal vector to achieve interference suppression.

2. The integrated space-ground anti-interference method according to claim 1, characterized in that, Step S2 includes: The following formula represents the number received by the ground station. Disturbed signals from individual satellites : In the formula, For communication signals, For interference signals, For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For communication signals via the first Total propagation delay of uplink and downlink relayed by each satellite For interference signals via the first Total propagation delay of uplink and downlink relayed by each satellite To receive the first... Total noise of uplink and downlink for each satellite For time.

3. The integrated space-ground anti-interference method according to claim 1, characterized in that, Step S3 includes: The following formula represents the number received by the ground station. The communication signals transmitted by the first satellite are compared to those of the second. The time difference of communication signals transmitted by each satellite : In the formula, The communication signal transmitted by the s-th satellite compared to the s-th satellite The delay difference of communication signals transmitted by each satellite For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For communication signals via the first Total propagation delay of uplink and downlink relayed by each satellite For interference signals via the first The total propagation delay of uplink and downlink relayed by each satellite.

4. The integrated space-ground anti-interference method according to claim 1, characterized in that, Step S3 further includes: The Taylor series of a delayed communication signal can be expressed by the following formula. : In the formula, For residual error, For communication signals First derivative, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For time; Substituting the Taylor series into the disturbed signal yields the disturbed signal of a single satellite with the delay difference eliminated. The formula is as follows: In the formula, For the first Error terms of each satellite For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For communication signals, For interference signals, For communication signals First derivative, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For time.

5. The integrated space-ground anti-interference method according to claim 1, characterized in that, Step S3 further includes: The total interference signal received by the ground station from all satellites is expressed by the following formula. : In the formula, To extend signal vector, To expand the channel matrix, For error terms, For time.

6. The integrated air-ground anti-interference method according to claim 5, characterized in that, Step S3 further includes: The extended signal vector is represented by the following formula. : in For communication signals, For communication signals First derivative, For interference signals, For transpose, For time.

7. The integrated space-ground anti-interference method according to claim 1, characterized in that, Step S4 includes: The whitening signal is represented by the following formula. : In the formula, To receive the total interference signals from all satellites received by the ground station; The whitening matrix is ​​expressed by the following formula. : In the formula, Covariances arranged in descending order Eigenvalues Eigenvalues Corresponding feature vectors , is the index of the eigenvalue.

8. The integrated air-ground anti-interference method according to claim 1, characterized in that, Step S5 includes: The estimated extended signal vector is extracted from the whitened signal according to the following formula. : In the formula, For whitening signal, For whitening matrix, To expand the channel matrix; The extended channel matrix is ​​expressed by the following formula. : In the formula, For the first The communication signals transmitted by the first satellite are compared to those of the second. The delay difference of communication signals transmitted by each satellite For communication signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, For interference signals via the first The equivalent channel coefficients of the uplink and downlink concatenated channels of each satellite, The number of cooperating satellites.

9. The integrated space-ground anti-interference method according to claim 1, characterized in that, Step S5 further includes: The two signals representing the estimated communication signal and the first derivative of the estimated communication signal in the extended signal vector are determined based on the covariance matrix of the extended signal vector. The signal with the lower average frequency among the two signals is identified as the estimated communication signal; The covariance matrix of the extended signal vector can be expressed by the following formula. : In the formula, For communication signals autocorrelation function For communication signals First derivative of communication signal cross-correlation function The first derivative of the communication signal and communication signals cross-correlation function The autocorrelation function of the first derivative of the communication signal. Interference signal The covariance matrix.

10. A space-ground integrated anti-interference system based on multi-satellite collaboration, applied to the space-ground integrated anti-interference method according to any one of claims 1-9, characterized in that, include: The ground station is used to send communication signals to cooperating and communication satellites; Jamming stations are used to send jamming signals to cooperative and communication satellites. The cooperative satellite and communication satellite are used to simultaneously receive the communication signal and the interference signal, obtain the interfered signal, and transmit the interfered signal to the receiving ground station; The receiving ground station is used to perform Taylor series expansion on the delayed communication signal using the propagation path of the satellite with the median delay difference among multiple satellites as the time reference, to separate the delay difference of the disturbed signal from the signal waveform, and to obtain the disturbed signal of a single satellite with the delay difference eliminated and the total disturbed signal of all satellites with the delay difference eliminated. The receiving ground station is also used to whiten the disturbed total signal to obtain a whitened signal; The receiving ground station is also used to rotate the whitened signal, extract the estimated extended signal vector from the whitened signal, and identify the estimated communication signal in the estimated extended signal vector to achieve interference suppression.

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