CN-122026945-A - Low-orbit radar satellite constellation cooperative frequency hopping anti-interference method and system

CN122026945ACN 122026945 ACN122026945 ACN 122026945ACN-122026945-A

Abstract

The invention provides a low-orbit radar satellite constellation cooperative frequency hopping anti-interference method and system, which comprise the steps that a ground control center generates a global frequency hopping time-frequency allocation table based on future orbit forecast data of a constellation, a satellite monitors interference signals in real time, local negotiation is initiated with a master control satellite through an inter-satellite link when an unforeseen interference source or task change is detected, a frequency band is selected in a reserved frequency resource table based on a negotiation result to be transmitted to an interfered satellite, the satellite receives interference signals to position the interfered satellite and analyze interference signal characteristics, and the satellite periodically evaluates the integral anti-interference performance index of the constellation by collecting historical interference data and reserving part of frequency resources as an anti-interference special frequency band so as to optimize the next round of pre-planning parameters. The invention solves the problems of poor dynamic adaptability, low cooperative efficiency and the like in the prior art by combining centralized pre-planning with on-board dynamic adjustment, and improves the anti-interference capability and the spectrum resource utilization rate of the low-orbit radar satellite constellation under a complex electromagnetic environment.

Inventors

CHEN JUNLI
LU QING
QU WEI
LIU YANYANG
XI PEILI
WAN XIANGCHENG

Assignees

上海卫星工程研究所

Dates

Publication Date: 20260512
Application Date: 20260114

Claims (10)

1. The low-orbit radar satellite constellation cooperative frequency hopping anti-interference method is characterized by comprising the following steps of: The method comprises the steps of 1, in a centralized pre-planning stage, a ground control center generates a global frequency hopping time-frequency allocation table based on orbit forecast data in a constellation future preset time length and uploads the global frequency hopping time-frequency allocation table to each satellite in the constellation, wherein the generation principle of the global frequency hopping time-frequency allocation table is that for any two satellites with a distance smaller than a preset distance threshold and with overlapping wave beams, the transmission frequency interval in the same time slot is larger than the preset frequency interval threshold; Step 2, in a dynamic adjustment stage on the satellite, the satellite in the constellation monitors interference signals in real time, and when the satellite detects an unforeseen interference source or task change, the satellite is used as an initiating satellite to initiate local negotiation with a main control satellite on the track surface through an inter-satellite link; And step 3, in the interference collection and optimization stage, the satellite positions the received interference signals and analyzes the interference signal characteristics, interference data comprising the positions of the interference sources and the signal characteristics are stored and periodically returned to the ground control center, and the ground control center reserves part of frequency resources in the global frequency hopping time-frequency allocation table as an anti-interference special frequency band based on the historical interference data collection result and periodically evaluates the overall anti-interference performance index of the constellation to optimize the next round of pre-planning parameters.
2. The method for low-orbit radar satellite constellation collaborative frequency hopping and interference avoidance according to claim 1, wherein in the centralized pre-planning stage, the specific step of generating the global frequency hopping time-frequency allocation table comprises: The ground control center calculates a distance matrix between satellites in a future period based on the orbit forecast data And beam overlap probability matrix Wherein Representation of Time satellite And satellite Is used for the distance of (a), Representation of Time satellite And satellite Is a beam overlap probability of (1); for distances less than a preset distance threshold And the beam overlapping probability is larger than a preset probability threshold Is assigned a frequency interval greater than a preset frequency interval threshold A transmission frequency; the method comprises the steps of performing frequency allocation optimization by adopting a graph coloring algorithm, wherein the optimization target is to minimize the total number of frequency segments used, the frequency interval redundancy of adjacent satellites and the frequency change of a single satellite in a period of time on the premise of meeting the frequency constraint of all satellites; the frequency allocation optimization is achieved by constructing and minimizing a comprehensive cost function F: Wherein: For the total number of frequency bins used, The sum of squares of the deviations of the satellite from the actual frequency spacing and the minimum requirement, Is the sum of squares of the frequency intervals in the satellite front and rear time periods, 、、 Is the weight; representing a minimized frequency allocation composite cost function; Representing a time interval between two adjacent planned time slots; The transmitting frequency of the satellite i at the time t is represented; the transmitting frequency of the satellite j at the time t is represented; And solving the comprehensive cost function F by adopting a genetic algorithm to generate the global frequency hopping time-frequency allocation table, wherein the allocation table agrees with the frequency band used by each satellite in the constellation in each planning time slot.
3. The method for resisting disturbance of cooperative frequency hopping of low-orbit radar satellite constellation according to claim 1, wherein in the on-board dynamic adjustment stage, a main control satellite dynamic coordination local decision is set, specifically comprising that a satellite is designated as a main control node for each orbit surface, a frequency adjustment request is sent to the main control satellite of the orbit surface where the main control satellite is positioned by an initiating satellite, the main control node arbitrates and generates a new frequency allocation decision containing a new frequency value and effective time, and the new frequency allocation decision is broadcasted to the relevant satellite through an inter-satellite link, when the main control satellite fails, the system is automatically switched to a standby main control node of the orbit surface; The local negotiation includes the steps of the initiating satellite broadcasting interference detection information and a frequency adjustment request to the master satellite through an inter-satellite link, the master satellite determining that the initiating satellite meets the requirements according to the received request The method comprises the steps of acquiring a set of related satellites, inquiring a reserved frequency resource table by a main control satellite, evaluating the influence of different frequency selections on satellite receiving performance in the set of related satellites, selecting a proper frequency band according to the influence and generating a frequency adjustment feedback decision, broadcasting the frequency adjustment feedback decision to an initiating satellite and the satellites in the set of related satellites by the main control satellite through inter-satellite links, and adjusting self-transmitting frequency by each satellite according to the decision; When a plurality of satellites initiate frequency adjustment requests at the same time, a priority mechanism is adopted to coordinate conflicts, specifically, priority values are given to the satellites according to the task types and the interference intensity of the requested satellites, wherein the priority of military task satellites is higher than that of civil task satellites, the priority of high-value target observation tasks is higher than that of conventional patrol tasks, the priority of satellites affected by strong interference is higher than that of satellites affected by weak interference, the interference intensity is quantified through the signal-to-interference-and-noise ratio reduction degree or the radar echo quality deterioration degree measured by the satellites in real time, the main control satellites process the frequency adjustment requests according to the order of the priority values from high to low, and the high-priority requests preferentially acquire and adjust frequency resources.
4. The method for low-orbit radar satellite constellation collaborative frequency hopping interference avoidance according to claim 1, wherein in the interference collection optimization stage, the satellite locates and performs feature analysis on the interference signal, and specifically comprises: the satellite carries out arrival angle estimation and time difference measurement through multichannel received signals so as to determine the spatial position of an interference source; Analyzing the frequency characteristic, the modulation mode and the time domain characteristic of the interference signal, identifying the interference type and extracting signal parameters including pulse width, repetition period and duty ratio; storing interference data records containing the position, signal characteristics and occurrence time of an interference source in a satellite solid-state storage module, and periodically returning the interference data records to a ground control center through a satellite-ground link to form an interference signal characteristic database; The reserved part of frequency resources are used as anti-interference special frequency bands, specifically, a ground control center marks part of frequency intervals which are not interfered or have low interference risks as the anti-interference special frequency bands when generating an all-office frequency hopping time-frequency allocation table aiming at specific frequency intervals with high interference probability or continuous interference risks in historical statistics based on a historical interference data feature library and threat information, and the special frequency bands are preferentially allocated to the satellite with the risk of being interfered in a pre-planning stage or are called as emergency frequency resources in an on-board dynamic adjustment stage.
5. The low-orbit radar satellite constellation collaborative frequency hopping anti-interference method according to claim 1, wherein the periodic evaluation of the overall anti-interference performance index of the constellation and optimization of the next round of pre-planning parameters specifically comprises: The ground control center calculates the interference suppression ratio, the bit error rate and the task completion rate of the constellation regularly as anti-interference performance indexes; According to the evaluation result of the performance index, adjusting and optimizing the preset distance threshold, the preset probability threshold and the preset frequency interval threshold used in the centralized pre-planning stage, and parameters of a graph coloring algorithm and a genetic algorithm to generate a new pre-planning parameter set; And generating a global frequency hopping time-frequency allocation table of the next round by using the optimized pre-planning parameter set, and realizing closed loop iterative optimization of the anti-interference strategy.
6. The utility model provides a low orbit radar satellite constellation cooperatees frequency hopping anti-interference system which characterized in that includes: The method comprises a module M1, a centralized pre-planning stage, a ground control center, a global frequency hopping time-frequency allocation table and a power module, wherein the ground control center generates a global frequency hopping time-frequency allocation table based on orbit forecast data in a constellation future preset time length and uploads the global frequency hopping time-frequency allocation table to each satellite in the constellation; The module M2 is used for monitoring interference signals in real time by satellites in a constellation in a dynamic adjustment stage on the satellite, and when the satellites detect unforeseen interference sources or task changes, the satellites are used as initiating satellites to initiate local negotiation with a main control satellite on the track surface where the satellites are positioned through inter-satellite links; And the ground control center reserves part of frequency resources in a global frequency hopping time-frequency allocation table as an anti-interference special frequency band based on the historical interference data collection result, and periodically evaluates the overall anti-interference performance index of the constellation to optimize the next round of pre-planning parameters.
7. The low-orbit radar satellite constellation collaborative frequency hopping anti-interference system according to claim 6, wherein in the centralized pre-planning stage, the specific step of generating the global frequency hopping time-frequency allocation table comprises: The ground control center calculates a distance matrix between satellites in a future period based on the orbit forecast data And beam overlap probability matrix Wherein Representation of Time satellite And satellite Is used for the distance of (a), Representation of Time satellite And satellite Is a beam overlap probability of (1); for distances less than a preset distance threshold And the beam overlapping probability is larger than a preset probability threshold Is assigned a frequency interval greater than a preset frequency interval threshold A transmission frequency; the method comprises the steps of performing frequency allocation optimization by adopting a graph coloring algorithm, wherein the optimization target is to minimize the total number of frequency segments used, the frequency interval redundancy of adjacent satellites and the frequency change of a single satellite in a period of time on the premise of meeting the frequency constraint of all satellites; the frequency allocation optimization is achieved by constructing and minimizing a comprehensive cost function F: Wherein: For the total number of frequency bins used, The sum of squares of the deviations of the satellite from the actual frequency spacing and the minimum requirement, Is the sum of squares of the frequency intervals in the satellite front and rear time periods, 、、 Is the weight; representing a minimized frequency allocation composite cost function; Representing a time interval between two adjacent planned time slots; The transmitting frequency of the satellite i at the time t is represented; the transmitting frequency of the satellite j at the time t is represented; And solving the comprehensive cost function F by adopting a genetic algorithm to generate the global frequency hopping time-frequency allocation table, wherein the allocation table agrees with the frequency band used by each satellite in the constellation in each planning time slot.
8. The system of claim 6, wherein in the on-board dynamic adjustment stage, a master satellite dynamic coordination local decision is set, specifically comprising designating a satellite as a master node for each track plane, wherein the frequency adjustment request is sent to the master satellite of the track plane where the master satellite is located by an initiating satellite, arbitrating by the master node, generating a new frequency allocation decision comprising a new frequency value and effective time, and broadcasting the new frequency allocation decision to related satellites through inter-satellite links; The local negotiation includes the steps of the initiating satellite broadcasting interference detection information and a frequency adjustment request to the master satellite through an inter-satellite link, the master satellite determining that the initiating satellite meets the requirements according to the received request The method comprises the steps of acquiring a set of related satellites, inquiring a reserved frequency resource table by a main control satellite, evaluating the influence of different frequency selections on satellite receiving performance in the set of related satellites, selecting a proper frequency band according to the influence and generating a frequency adjustment feedback decision, broadcasting the frequency adjustment feedback decision to an initiating satellite and the satellites in the set of related satellites by the main control satellite through inter-satellite links, and adjusting self-transmitting frequency by each satellite according to the decision; When a plurality of satellites initiate frequency adjustment requests at the same time, a priority mechanism is adopted to coordinate conflicts, specifically, priority values are given to the satellites according to the task types and the interference intensity of the requested satellites, wherein the priority of military task satellites is higher than that of civil task satellites, the priority of high-value target observation tasks is higher than that of conventional patrol tasks, the priority of satellites affected by strong interference is higher than that of satellites affected by weak interference, the interference intensity is quantified through the signal-to-interference-and-noise ratio reduction degree or the radar echo quality deterioration degree measured by the satellites in real time, the main control satellites process the frequency adjustment requests according to the order of the priority values from high to low, and the high-priority requests preferentially acquire and adjust frequency resources.
9. The low-orbit radar satellite constellation collaborative frequency hopping anti-interference system according to claim 6, wherein in the interference collection optimization phase, the satellite locates and analyzes the characteristics of the interference signal, comprising: the satellite carries out arrival angle estimation and time difference measurement through multichannel received signals so as to determine the spatial position of an interference source; Analyzing the frequency characteristic, the modulation mode and the time domain characteristic of the interference signal, identifying the interference type and extracting signal parameters including pulse width, repetition period and duty ratio; storing interference data records containing the position, signal characteristics and occurrence time of an interference source in a satellite solid-state storage module, and periodically returning the interference data records to a ground control center through a satellite-ground link to form an interference signal characteristic database; The reserved part of frequency resources are used as anti-interference special frequency bands, specifically, a ground control center marks part of frequency intervals which are not interfered or have low interference risks as the anti-interference special frequency bands when generating an all-office frequency hopping time-frequency allocation table aiming at specific frequency intervals with high interference probability or continuous interference risks in historical statistics based on a historical interference data feature library and threat information, and the special frequency bands are preferentially allocated to the satellite with the risk of being interfered in a pre-planning stage or are called as emergency frequency resources in an on-board dynamic adjustment stage.
10. The low-orbit radar satellite constellation collaborative frequency hopping anti-interference system according to claim 6, wherein the periodic evaluation of the overall anti-interference performance index of the constellation and optimization of the next round of pre-planning parameters specifically comprises: The ground control center calculates the interference suppression ratio, the bit error rate and the task completion rate of the constellation regularly as anti-interference performance indexes; According to the evaluation result of the performance index, adjusting and optimizing the preset distance threshold, the preset probability threshold and the preset frequency interval threshold used in the centralized pre-planning stage, and parameters of a graph coloring algorithm and a genetic algorithm to generate a new pre-planning parameter set; And generating a global frequency hopping time-frequency allocation table of the next round by using the optimized pre-planning parameter set, and realizing closed loop iterative optimization of the anti-interference strategy.

Description

Low-orbit radar satellite constellation cooperative frequency hopping anti-interference method and system Technical Field The invention relates to the technical field of low-orbit radar satellite anti-interference, in particular to a low-orbit radar satellite constellation cooperative frequency hopping anti-interference method and system. Background The low orbit radar satellite constellation is a key means for earth observation and target monitoring by virtue of global coverage and high space-time resolution. Along with SpaceX, planet Labs and other companies accelerating deployment of large-scale low-orbit remote sensing constellations (> 100 satellites), the space density of satellites in the constellations is obviously improved, the minimum space of low-orbit radar satellites is reduced to below 300km, along with the increasing tension of spectrum resources, the signal interference among satellites (the same-frequency/adjacent-frequency interference caused by overlapping and too close distance with the constellation satellite wave beams) and the frequency of external malicious interference (such as hostile targeted electromagnetic suppression and stray interference invasion) severely limit the reliability of constellation tasks. The frequency hopping technology is used as an anti-interference classical means and is preliminarily applied to single-satellite or simple satellite networking, but under the complex scene of multi-satellite, multi-track surface and dynamic topology of a low-orbit constellation, the traditional frequency hopping scheme has the problems of insufficient coordination, difficult resource allocation and the like, and a cooperative frequency hopping anti-interference system adapting to the constellation characteristics of the low-orbit radar satellite needs to be constructed. The literature (Shi, zhang Bangning, etc. computer engineering, 2018,02) discloses a multi-beam satellite power bandwidth joint allocation algorithm considering inter-beam interference, which is characterized in that a bandwidth power joint allocation model is constructed by introducing interference coefficients, a resource allocation problem is split into three sub-problems of power allocation, bandwidth allocation and dual variable updating, and a corresponding allocation algorithm is provided. The method is mainly used for solving the problem that interference exists among beams due to frequency multiplexing of a communication satellite, and is not suitable for a radar satellite system. The document 'wireless communication anti-interference research based on constellation diagram transformation' (Yu Xingguo, yuan Tao, etc. computer knowledge and technology, 2024,01.) proposes an anti-interference method based on constellation diagram transformation of a phase modulator combined with modulation hopping technology. The signal is encrypted by constellation diagram transformation of the transmitted signal, and simultaneously, the signal is combined with a modulation hopping technology, so that different modulation modes are adopted when the signal is transmitted at different carrier frequencies. The method improves the security of signal transmission in an encryption mode, and cannot be suitable for anti-interference application among constellations. The literature (Shi Yoxin, li Yusheng, etc. the journal of electric wave science, 2023,05.) proposes three coping strategies of utilizing interference, countering interference or not needing measures, and is a more flexible and effective anti-interference means compared with the traditional index modulation frequency hopping method. The method improves the anti-interference capability of the system by improving the bit error rate performance, and does not consider the problem of mutual interference among satellites in a constellation. The literature (Yue, wu Xiaofu, etc. radio communication technology, 2023,06.) designs an anti-interference deep Q network algorithm decision neural network based on the combination of an attention mechanism and a long-short-time memory network, which can rapidly extract time-frequency structure information in a short-time frequency spectrum waterfall diagram, thereby realizing the on-line training acceleration of the decision neural network. Aiming at the intelligent anti-interference communication scene of frequency hopping, the method for analyzing the interference by utilizing the deep learning method is provided, and is not suitable for anti-interference among radar satellites. The patent 'satellite-borne SAR anti-interference method based on frequency modulation time-varying complex waveform' (patent number: CN 202110313983.4) designs a class of complex modulation signals with low cross correlation and high autocorrelation characteristics, and simultaneously, the energy of originally focused deception interference is dispersed to a distance-azimuth two-dimensional plane by periodically transmitting and adding a random phase transm