Intelligent reflecting surface based wireless charging method for planetary explorer
By deploying intelligent reflectors and space-based solar satellites on planetary probes, and combining identity authentication and optimization algorithms, the problems of wireless charging efficiency and security for planetary probes have been solved, achieving continuous power supply and secure access.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHWESTERN POLYTECHNICAL UNIV
- Filing Date
- 2026-01-29
- Publication Date
- 2026-06-23
AI Technical Summary
Existing laser-based wireless charging methods for planetary probes face challenges in terms of charging efficiency and access security, especially with efficiency degradation in long-distance transmission, highly dynamic networks, and extreme environments, and they fail to effectively prevent attacks from malicious nodes.
A wireless charging method for planetary probes based on intelligent reflectors is adopted, combining a space solar satellite and an intelligent reflector (IRS). Through an identity authentication mechanism and an alternating optimization algorithm, the beamforming vector and the IRS phase shift matrix are optimized to maximize energy transmission. Furthermore, the wireless transmission environment is reconfigured through the IRS to reshape the signal wavefront and ensure secure access.
It achieves continuous 24/7 power supply in extreme environments, improves charging efficiency, and ensures system access security through an identity authentication mechanism to prevent attacks from malicious detectors.
Smart Images
Figure CN122267337A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of planetary exploration and wireless charging, and specifically to a wireless charging method for planetary probes based on Intelligent Reflecting Surfaces (IRS). Background Technology
[0002] Planetary exploration is of great scientific significance in exploring the origin of life, expanding human living space, developing space energy, preventing asteroid impacts, and studying severe weather. During planetary exploration, it is necessary to systematically observe and collect data on planetary topography, soil composition, and environmental characteristics, and then transmit key data back to Earth via a stable communication link. These missions place extremely high demands on energy resources; the probes must have a reliable and continuous power supply, making efficient charging technology particularly crucial.
[0003] Current technologies typically combine lithium-ion batteries and solar panels to charge planetary probes. However, because planets are usually far from the sun (such as Mars and Jupiter), solar irradiance is weak, significantly reducing solar charging efficiency. Furthermore, extreme weather events on planets (such as dust storms that can last for weeks or even months on Mars, and extreme winds and torrential rains on Jupiter) further weaken sunlight, easily causing energy interruptions. On the other hand, during a solar eclipse or when a planetary probe is in the sun's shadow, solar systems cannot be used for charging, preventing a continuous energy supply. While nuclear energy can provide a stable and continuous energy supply, its research and deployment costs are high, applicable radioactive isotope resources are limited, and it carries radiation safety risks.
[0004] To address the aforementioned challenges, wireless charging methods based on space-based solar satellites are considered a potential solution for providing stable and green energy to planetary probes. Among these, laser-based wireless charging methods have become an important research direction due to their advantages such as strong directionality, high energy density, and long transmission distance. However, due to the extremely long transmission distance between planets and space-based solar satellites, the extreme environments of planets, and the highly dynamic characteristics of space-based solar satellites, the charging efficiency of laser-based wireless charging methods still faces many challenges. Furthermore, most existing research focuses only on energy transmission efficiency, neglecting the serious security risks that may result from attacks such as malicious nodes impersonating legitimate devices. Summary of the Invention
[0005] The purpose of this invention is to provide a wireless charging method for planetary probes based on intelligent reflective surfaces, which, in conjunction with space solar-powered satellites, solves the problems of existing laser-based wireless charging methods in terms of charging efficiency and access security.
[0006] To achieve the above objectives, the present invention employs the following technical solution: A wireless charging method for planetary probes based on smart reflective surfaces includes: The plan includes deploying a wireless charging system on the target planet, including multiple space solar satellites deployed in geosynchronous orbit on the target planet and an intelligent reflective surface (IRS) on the surface of the target planet; and having planetary probes on the target planet, including legitimate planetary probes and potentially malicious planetary probes. The space solar satellite employs an IRS-based challenge-response physical layer authentication mechanism to authenticate the receiver. Once the receiver is confirmed to be a legitimate planetary probe, the energy transfer phase begins. First, the beamforming vector and IRS phase shift matrix of the space solar satellite are jointly solved using an alternating optimization algorithm. Simultaneously, from the currently visible space solar satellites, the space solar satellite used for energy transfer is selected with the goal of maximizing the received energy of the legitimate planetary probe. Then, the transmit power and IRS phase of the space solar satellite are configured according to the beamforming vector and IRS phase shift matrix. Finally, the selected space solar satellite begins energy transfer, with a portion of the energy being directly absorbed via the space solar satellite-legitimate planetary probe direct link, and the other portion reaching the legitimate planetary probe via the IRS reflection link, thereby maximizing the received energy of the legitimate planetary probe.
[0007] Furthermore, the space-based solar satellite employs an IRS-based challenge-response physical layer authentication mechanism to authenticate the receiver, which includes two stages: identity association and identity verification. During the identity verification phase, legitimate planetary probes send signals to space-based solar satellites. Sending a pilot signal, space solar satellite By activating all IRS phase configurations in turn, the received signals are detected and estimated, thereby constructing the channel response of a legitimate planetary probe under different configurations. This completes the identity verification process and forms the physical layer fingerprint information of the legitimate planetary probe.
[0008] During the identity verification phase, the space-based solar satellite Randomly configuring IRS as a challenge; when space solar satellites Upon receiving a signal from a planetary probe, it uses its pre-stored channel response. With real-time received channel response Perform matching; if the signal originates from a legitimate planetary probe, the estimated channel response is: , For the identity verification phase of space solar satellites The estimation error at that point; if it originates from a malicious planetary probe, the estimated channel response is... , The channel response was forged by a malicious planetary probe.
[0009] Furthermore, malicious planetary probes spoofed channel responses Represented as: , Expressing expectations, For space-based solar satellites The equivalent channel response is formed by the channel response of the direct channel to the planetary probe and the channel of the IRS reflection link. For space-based solar satellites Channel response of the direct channel between the planetary probe and the probe; For space-based solar satellites To the IRS Channel response of each reflecting element; For the IRS Channel response from each reflector element to the planetary probe; Indicates random phase shift Statistical expectation; For the IRS Optimal phase offset configuration of each reflective element It is a natural constant. The imaginary unit, It is a collection of space-based solar-powered satellites.
[0010] Furthermore, when verifying the identity of the launcher, the space solar satellite... The currently estimated channel response Compared with previously stored channel responses Compare; define for: ; in As an identity indicator variable, This indicates that the launcher is a legitimate planetary probe. This indicates that the launcher is a malicious planetary probe; Based on this, the following two assumptions are made: Null hypothesis H0: It is assumed that the sender of the message is a legitimate planetary probe; Alternative hypothesis H1: It is assumed that the sender of the message is a malicious planetary probe; The verification result is denoted as... ,like If so, it indicates that the authentication has been successful; The generalized likelihood ratio test is used for calculation, based on the H0 assumption and the IRS phase shift matrix selected by the given space solar satellite. Test statistic It can be written as: This is used to measure the difference between the current channel response and the stored fingerprint; where This represents the IRS phase shift matrix selected for a given space solar satellite. Channel response of a legal planetary probe; This represents the variance of the additive white Gaussian noise; next, the test statistic is... With threshold The comparison and authentication rules are as follows: ; That is when If the launcher is legitimate, it is determined to be a legitimate planetary probe; otherwise, it is determined to be a malicious planetary probe.
[0011] Furthermore, when space-based solar satellites transmit energy to planetary probes, the signals experience free-space path loss. Molecular absorption loss and scattering caused by dust Transmission loss It can be represented as: ;in, For carrier frequency, This indicates the propagation delay of a signal from a space-based solar-powered satellite to a planetary probe; At any moment Space-based solar satellite The channel response of the direct channel between the planetary probe and the probe can be expressed as: ,in and These are space-based solar satellites Gain of the transmitting antenna in the direction of the planetary probe and gain of the receiving antenna in the space solar satellite Directional gain; space-based solar satellites To the IRS The channel response of a single reflecting element can be expressed as: ,in The reflectivity is the incident energy. For carrier wavelength, for Time Space Solar Satellite Location, For the IRS The position of each reflective element and For space-based solar satellites The upper transmitting antenna is in the IRS. Gain in the direction of each reflector and IRS A reflective element in a space solar satellite Gain in the direction of the transmitting antenna; IRS number Channel response from each reflecting element to the planetary probe: ,in and For the IRS The gain of each reflective element in the direction of the planetary probe and the receiving gain of the planetary probe; for The location of the planetary probe at any given time; Based on the above results, we can obtain Time Space Solar Satellite The emitted energy passes through the IRS. Cascaded channel response of a reflective element: And the equivalent channel response formed by the channel response of the direct channel and the channel of the IRS reflection link: ;in, IRS phase shift matrix The Middle The complex phase shift coefficient of each reflecting element, for Time IRS Phase shift of each reflective element; This leads to the development of space-based solar satellites. The received power of the emitted energy at the planetary probe is expressed as: ; where the parameter superscript This indicates the conjugate transpose. express Beamforming vector of a space-time solar satellite; Finally, we get Energy collected by the planetary probe: ; in ,when When, it means at Time Space Solar Satellite Selected for energy transfer This indicates that it was not selected; This indicates the efficiency with which radio frequency energy is converted into DC energy at the planetary probe after transmission; This refers to the time it takes for energy to transfer.
[0012] Furthermore, when jointly solving the selection of space solar satellites, beamforming vectors, and IRS phase shift matrices using an alternating optimization algorithm, the objective function and constraints of the optimization problem are as follows: ; in, Indicates space-based solar satellite The choice of variables, express Beamforming vector of a space-based solar satellite at any given time. for Time IRS The complex phase shift coefficient of each reflecting element; for The selection of space-based solar satellites at any given time express A collection of space-based solar-powered satellites that are always visible to planetary probes; This is the maximum acceptable false negative threshold for the system.
[0013] Furthermore, the optimization problem is solved using an alternating optimization algorithm. By alternatingly optimizing the IRS phase shift matrix, the beamforming vector of the space solar satellite, and the selection strategy of the space solar satellite, the energy received by the planetary probe is maximized.
[0014] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor executes the computer program, it implements the wireless charging method for a planetary probe based on a smart reflector.
[0015] A computer-readable storage medium storing a computer program; when executed by a processor, the computer program implements the wireless charging method for a planetary probe based on a smart reflector.
[0016] Compared with the prior art, the present invention has the following technical features: This invention effectively solves the problem of reduced transmission efficiency caused by long-distance transmission, highly dynamic networks, and extreme environments, and achieves continuous 24 / 7 power supply. It can reconfigure the wireless transmission environment using the IRS and reshape the signal wavefront of the planetary probe. By jointly optimizing the selection of space solar satellites, beamforming vectors, and the phase shift matrix of the IRS, it improves the energy reception of the planetary probe. Simultaneously, it authenticates the target probe through an IRS-based challenge-response physical layer authentication mechanism, achieving secure access; thus improving the charging efficiency of the planetary probe while ensuring system access security. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the wireless charging method for a Mars probe based on IRS in this invention. Figure 2 A schematic diagram illustrating the charging of the Mars probe based on IRS in this invention; Figure 3 This is the convergence graph of the alternating optimization algorithm in this invention; Figure 4 This is a graph showing the time consumption of the alternating optimization algorithm in this invention as a function of the number of IRS reflective elements; Figure 5 This is a graph showing the variation of the energy received by the Mars probe as a function of the number of IRS reflective elements in this invention. Figure 6 This is a graph showing the variation of the safety indicator false detection rate with the number of IRS reflective elements in this invention. Detailed Implementation
[0018] This invention provides a wireless charging method for planetary probes based on a smart reflector. It leverages an IRS (Infrastructure Responsibility Regulator) to reconfigure the wireless transmission environment and reshape the signal wavefront of the planetary probe. By jointly optimizing the selection of space solar-powered satellites, beamforming vectors, and the phase shift matrix of the IRS, it improves the energy reception of the planetary probe. Simultaneously, it authenticates the target probe through an IRS-based challenge-response physical layer authentication mechanism, achieving secure access. This system improves the charging efficiency of planetary probes while ensuring system access security. Figure 1 As shown, the method includes: The plan includes deploying a wireless charging system on the target planet, including multiple space solar satellites deployed in geosynchronous orbit on the target planet and an intelligent reflective surface (IRS) on the surface of the target planet; and having planetary probes on the target planet, including legitimate planetary probes and potentially malicious planetary probes. The space solar satellite employs an IRS-based challenge-response physical layer authentication mechanism to authenticate the receiver. Once the receiver is confirmed to be a legitimate planetary probe, the energy transfer phase begins. First, an alternating optimization algorithm is used to jointly solve for the selection of the space solar satellite, the beamforming vector, and the IRS phase shift matrix. Then, based on the beamforming vector and the IRS phase shift matrix, the transmit signals of each antenna of the selected space solar satellite and the IRS phase are configured. From the currently visible space solar satellites, the space solar satellite used for energy transfer is selected with the goal of maximizing the received energy of the legitimate planetary probe. Finally, the selected space solar satellite begins energy transfer, with a portion of the energy being directly absorbed via the space solar satellite-legitimate planetary probe direct link, and the remaining energy reaching the legitimate planetary probe via the IRS reflection link, thus maximizing the received energy of the legitimate planetary probe. The specific implementation process of this invention will be further described in detail below with reference to the accompanying drawings.
[0019] In this embodiment of the invention, Mars is used as an example for illustration; first, the wireless charging system is deployed, and then the following steps are performed: Step 1: Construct a safe wireless charging model for the Mars rover based on a space-based solar satellite and an intelligent reflector IRS.
[0020] like Figure 2 As shown, the wireless charging system deployed for Mars specifically includes a radius of... Quality is Mars, The orbital height is Mars-Sun-synchronous orbital planes, each orbital plane includes Each equipped with A space-based solar satellite with one antenna receives solar energy and converts it into electrical energy; its radius is denoted as... The wireless charging system has a total of A set of space-based solar satellites. .
[0021] In addition, features were also set up on the surface of Mars. OK The intelligent reflective surface IRS of the array of reflective elements, the number of reflective elements The IRS phase shift matrix is represented as follows: ,in Indicates the IRS number Phase shift introduced by each reflective element It is a natural constant. The unit is the imaginary unit, and each reflective element satisfies the unit modulus constraint. ,in, For the IRS The complex phase shift coefficient of each reflecting element, , ; express Complex space of dimension 1 and These are row indexes and column indexes, respectively; the Mars probe includes a legitimate Mars probe with a single antenna and a malicious Mars probe with a single antenna; assuming in the worst-case scenario the malicious Mars probe is located around the legitimate Mars probe and possesses all real-time channel state information except for the IRS; the space solar satellite uses beamforming vectors... Send data, Satisfying constraints , The maximum power budget for the space solar satellite; to defend against malicious Mars probes masquerading as legitimate probes and stealing energy from the space solar satellite, a challenge-response-based physical layer security authentication using IRS is employed; specifically, the secure wireless charging model for Mars probes based on the space solar satellite and IRS comprises the following three sub-models: (1) Solar energy collection model of space solar satellite.
[0022] Generally, the energy collected by a space-based solar satellite depends on the area of its solar panels. Photovoltaic energy conversion efficiency and the angle between sunlight and the normal to the solar panels of a space-based solar satellite. Based on this, we first construct a model of the angle between sunlight and the normal to the solar panel of a space-based solar satellite: ; in The rotation angle of the space-based solar satellite starting from the center of the shaded area. The angle between the orbital plane of a space-based solar satellite and sunlight is defined; a solar energy collection model is then constructed based on this angle.
[0023] Assuming the sun is at its aphelion and the rays are approximately parallel; since the space-based solar satellite is in continuous motion, the energy it collects varies at different times. Therefore, this scheme characterizes the overall energy collected by integrating the energy collection process: ; in Solar irradiance per unit area. , The angular velocity of the space-based solar-powered satellite. For time parameters, An angle equal to half the shaded area, determined by the radius of Mars. Track height Orbital radius of space solar satellites as well as Decide: ; in, As an indicator variable, when hour, This indicates that the space-based solar satellite can receive sunlight at this time; otherwise... .in, This indicates the modulo operation.
[0024] (2) IRS-assisted wireless power transfer model for space solar satellites and Mars probes.
[0025] The efficiency of wireless power transmission determines the amount of energy the Mars probe can receive, and this efficiency mainly depends on the channel gain of the wireless transmission link. In this embodiment, when a space-based solar satellite transmits energy to the Mars probe, the signal experiences free-space path loss. Molecular absorption loss and scattering caused by dust Therefore, transmission loss It can be represented as: ;in, For carrier frequency, This indicates the propagation delay of a signal from a space-based solar-powered satellite to a Mars probe. This refers to the distance a signal travels from the transmitter (a space-based solar satellite) through dust to the receiver (a Mars probe). and They are The positions of the receiver and transmitter at all times. It represents the speed of light.
[0026] Considering the dynamic characteristics of space-based solar satellites, the channel response in this scheme is modeled as a function of time. The function. Therefore, based on the above analysis, at time... Space-based solar satellite The channel response of the direct channel between the Mars probe and the Mars rover can be expressed as: ,in and These are space-based solar satellites Gain of the transmitting antenna in the direction of the Mars probe and gain of the receiving antenna in the space solar satellite Gain in direction.
[0027] Similarly, at time Space solar satellite To the IRS The channel response of a single reflecting element can be expressed as: ,in The reflectivity is the incident energy. For carrier wavelength, for Time Space Solar Satellite Location, For the IRS The position of each reflective element and For space-based solar satellites The upper transmitting antenna is in the IRS. Gain in the direction of each reflector and IRS A reflective element in a space solar satellite Gain in the direction of the transmitting antenna.
[0028] Furthermore, calculate using the same method. Time IRS Channel response from each reflector to the Mars rover: ,in and For the IRS The gain of each reflector in the direction of the Mars probe and the receiving gain of the Mars probe; for The location of the Mars rover at any given time.
[0029] Based on the above results, we can obtain Time Space Solar Satellite The emitted energy passes through the IRS. Cascaded channel response of a reflective element: And the equivalent channel response formed by the channel response of the direct channel and the channel of the IRS reflection link: ;in, for The median coordinate is The element represents the IRS number. The complex phase shift coefficient of each reflecting element, for Time IRS Phase shift of each reflective element.
[0030] This leads to the development of space-based solar satellites. The received power of the emitted energy at the Mars probe is expressed as: ; where the parameter superscript This indicates the conjugate transpose. express Beamforming vector of a space-time solar satellite.
[0031] Finally, we get Energy collected by the Mars rover: ; in ,when When, it means at Time Space Solar Satellite Selected for energy transfer This indicates that it was not selected; This indicates the efficiency of converting radio frequency energy into DC energy at the Mars probe after transmission; the energy transfer time. It can be represented as: ,in This represents the efficiency of converting DC energy into radio frequency energy for transmission in a space solar satellite. The formula represents the upper limit of wireless energy transmission time, which is determined by the energy supply capacity and the line-of-sight window of the space solar satellite to the Mars probe, taking the minimum of the two.
[0032] (3) Challenge-response physical layer authentication model based on IRS.
[0033] This embodiment considers the possibility of malicious Mars probes masquerading as legitimate Mars probes to receive energy transmitted by space solar satellites, thereby reducing transmission efficiency and potentially damaging transmission equipment. To address this, the present invention proposes a challenge-response physical layer authentication mechanism based on IRS, which mainly includes two stages: identity association and identity verification. Given that challenge-response physical layer authentication mechanisms require rapid completion, this step assumes that the channel during the authentication process is quasi-static, meaning that the impact of time on the channel response is not considered in this step.
[0034] Specifically, during the identity verification phase, the legitimate Mars probe sends a signal to the space-based solar-powered satellite. Sending a pilot signal, space solar satellite By activating all IRS phase configurations in turn, the received signals are detected and estimated, thereby constructing the channel response of a legitimate Mars rover under different configurations. This completes the identity verification process and forms the physical fingerprint information of the legitimate Mars probe.
[0035] During the identity verification phase, the space-based solar satellite Randomly configuring IRS as a challenge; when space solar satellites Upon receiving a signal from the Mars probe, it uses its pre-stored channel response... With real-time received channel response Perform matching; if the signal originates from a legitimate Mars probe, the estimated channel response is: , For the identity verification phase of space solar satellites The estimation error at point follows a mean of 0 and a variance of . The additive white Gaussian noise distribution; if it originates from a malicious Mars probe, the estimated channel response is... , The channel response was forged by a malicious Mars probe.
[0036] Because malicious Mars probes can use their knowledge of space-based solar satellites... The information is used to adjust the attack strategy, therefore It can be represented as: , For space-based solar satellites The equivalent channel response is formed by the channel response of the direct channel to the Mars probe and the channel of the IRS reflection link. For space-based solar satellites Channel response of the direct channel between Mars probe and Mars probe; For space-based solar satellites To the IRS Channel response of each reflecting element; For the IRS Channel response from each reflector element to the Mars rover; Indicates random phase shift The statistical expectation, i.e., the random channel response of a malicious Mars probe. Expectations Used as the best guess; For the IRS Optimal phase offset configuration of each reflective element.
[0037] Specifically, when verifying the identity of the launcher, the space solar satellite... The currently estimated channel response Compared with previously stored channel responses Compare; define for: ; in As an identity indicator variable, This indicates that the launch vehicle is a legitimate Mars probe. This indicates that the launcher is a malicious Mars probe.
[0038] Based on this, the following two assumptions are made: Null hypothesis H0: It is assumed that the message was sent by a legitimate Mars probe; Alternative hypothesis H1: It is assumed that the message was sent by a malicious Mars probe.
[0039] The verified judgment result is denoted as ,like This indicates that the certification has been passed; for example, when the launcher is indeed a legitimate Mars probe, that is... And at this time, space-based solar satellites The launch vehicle was determined to be a legitimate Mars probe, i.e., the judgment result. If the result is , it indicates that the identity verification was successful.
[0040] Due to space solar satellites While possessing information on legitimate Mars probe channel information, the system lacks information on malicious Mars probe channel information. Therefore, a test statistic is established based on the known legitimate channel model. Specifically, the system employs the Generalized Likelihood Ratio Test (GLRT) for calculation. Under this method, the GLRT is based on the H0 hypothesis and the IRS phase shift matrix selected by the given space solar satellite. Test statistic It can be written as: This is used to measure the difference between the current channel response and the stored fingerprint; where This represents the IRS phase shift matrix selected for a given space solar satellite. Channel response of a legitimate Mars probe; This represents the variance of the additive white Gaussian noise; next, the test statistic is... With threshold The comparison and authentication rules are as follows: ; That is when If the launcher is legitimate, it is determined to be a Mars probe; otherwise, it is determined to be a malicious Mars probe.
[0041] Based on the above judgment, the security performance of this authentication mechanism should be further evaluated from a statistical perspective.
[0042] Specifically, two metrics are used for measurement: false alarm (FA) and missed detection (MD). FA refers to the false alarm rate, assuming the launch source is a legitimate Mars probe, and the space solar satellite... The launch vehicle was determined to be a malicious Mars probe. Specifically, under H0 conditions, a space-based solar-powered satellite... Accepting the H1 hypothesis, it can be expressed as: ; It represents probability.
[0043] Under the hypothesis H0, the test statistic is... It follows a central chi-square distribution with 2 degrees of freedom, therefore the above formula can be expressed as: ;in It has 2 degrees of freedom and the non-central parameter is The cumulative distribution function of a non-central chi-square random variable; by inversely solving this equation, the threshold is obtained. The expression: .
[0044] MD refers to a space-based solar-powered satellite launched under the premise that the launcher is a malicious Mars probe. The launch vehicle was determined to be a legitimate Mars probe; that is, under conditions H1, a space-based solar-powered satellite. The hypothesis H0 was accepted. Under hypothesis H1, the test statistic... The transformation to a noncentral chi-square distribution with 2 degrees of freedom is expressed as: Therefore, the probability of MD can be expressed as: The above formula can be written as: ;in It has 2 degrees of freedom and the non-central parameter is The cumulative distribution function of a noncentral chi-square random variable.
[0045] As mentioned earlier, malicious Mars probes can adjust their attack strategies based on information about space-based solar satellites; therefore, this scheme uses expected value. This is used to represent the channel response of a malicious Mars probe. Similarly, this scheme is based on... calculate expect: ,in Represents expectation, parameters It is expressed as follows: ; in, This is the optimal phase shift matrix for the IRS. To select the optimal phase shift matrix for space-time solar satellites The equivalent channel response is formed by combining the channel response of the direct channel to the Mars probe and the channel of the IRS reflection link. IRS phase shift matrix selected for a given space solar satellite Lower space solar satellite The equivalent channel response is formed by combining the channel response of the direct channel to the Mars probe and the channel of the IRS reflection link. The IRS selected for space solar satellites Phase shift of each reflective element, .
[0046] Step 2: Jointly optimize the selection of space solar satellites, beamforming vectors, and IRS phase shift matrix in the wireless charging system of Step 1, and consider security constraints to establish an optimization problem that maximizes the received energy.
[0047] Specifically, the objective function is the maximization defined in step (2) of step 1. The Mars probe receives energy at all times. Considering constraints such as the selection of a space solar satellite, transmission power constraints, IRS phase shift constraints, and security constraints, the objective function and constraints of the optimization problem can be written as follows: ; in express Beamforming vector of a space-based solar satellite at any given time. for Time IRS The complex phase shift coefficient of each reflecting element; for The selection of space-based solar satellites at any given time express A collection of space-based solar-powered satellites that are always visible to the Mars probe; This is the maximum acceptable false negative threshold for the system.
[0048] Step 3: Solve the optimization problem using an alternating optimization algorithm. By alternating the optimization of the IRS phase shift matrix, the beamforming vector of the space solar satellite, and the selection strategy of the space solar satellite, maximize the energy received by the Mars probe.
[0049] The optimization problem is decomposed into three solvable subproblems. Within each subproblem, while solving for one variable, the other two variables are fixed, and a closed-form solution is derived for each variable, using an iterative method to solve step by step. Before solving the optimization problem, firstly based on... The safety constraints are calculated, and then it is determined whether the results satisfy the safety constraints during subsequent solution processes. The specific process is as follows: Step 3-1, Derivation The formula relating the phase of the IRS reflection is used to determine whether the IRS phase shift matrix satisfies the condition in each iteration of the alternating optimization algorithm. constraint.
[0050] Specifically, from the above The formula is used to calculate the result. : ; For convenience, this solution uses .because Follow the mean variance is The Gaussian distribution, i.e. ,but It follows an exponential distribution, and its cumulative density function can be expressed as: Based on this, It can be rewritten as: ; Substitute the above formula into From the constraints, we get: And it is calculated using the following formula. : ; As can be seen from the above formula, The value mainly depends on . Specifically, Increase, then Decline. Furthermore, depending on , The larger the value, the more random the IRS phase shift. The larger the value, the better; therefore, this solution can be controlled. This ensures that safety constraints remain within a given range. Furthermore, this solution requires selecting the optimal [method / strategy]. In other words, it needs to be reduced. To minimize the randomness of the data and maximize the energy collected by the Mars rover, an alternating optimization algorithm is chosen to balance these two objectives.
[0051] Step 3-2: Solve for the optimal IRS phase configuration using an element-wise alternating optimization algorithm. .
[0052] Step 3-2-1, Fix the beamforming vector at the transmitting end and selection set of space solar satellites Rewrite the objective function: ; Since in this optimization step, all variables at any time The calculation and update methods are the same; to simplify the expression, the time subscript will be omitted uniformly in the following text. .
[0053] Step 3-2-2, Rewrite Separate And rewrite the objective function.
[0054] Specifically, rewrite for and use the following variables , , Representing direct channel response and space-based solar satellite respectively. -IRS channel response and IRS-Mars rover channel response. Substitute these variables into the above... The formula yields: ; in This is a vector representation of the IRS phase offset. For Hadama accumulation.
[0055] Furthermore, let , Then the objective function can be further rewritten as: ; in, , , , for The complex conjugate, This represents taking the real part of the complex number. The objective function is finally rewritten as: ; Step 3-2-3: Use the element-wise alternating optimization algorithm to obtain the optimal IRS phase shift matrix. .
[0056] make Expand on its discussion of the IRS A portion of the reflective element. For ease of description, the two-dimensional element arrangement of the IRS is mapped to a one-dimensional index. Let... ,in ,but The only corresponding IRS number One reflective element. (This is followed by a seemingly unrelated sentence: "Obtain a reflective element.") .in, , indicating the IRS number Phase shift of each reflective element, For the IRS Optimal phase offset of each reflective element Representation matrix The first in One element, For the IRS Phase shift of each reflective element Representing vectors The Each element. Is with Irrelevant constants, in This can be removed during optimization. Further consideration should be given to the constraints. The objective function can be rewritten as ; in Solving this problem yields the following results: ; Vector representation is ,in The optimal phase shift matrix for the IRS is derived from the current phase shift matrix. Calculated.
[0057] Step 3-2-4, the test results Does it satisfy the security constraints in step 3-1?
[0058] Specifically, if the constraints are satisfied, the original result is retained; if the constraints are not satisfied, then... in Indicates satisfaction The amount of phase change constrained can be obtained through step 3-1.
[0059] Step 3-3: Solve for the optimal beamforming vector through eigenvalue decomposition.
[0060] Specifically, assuming the IRS phase shift matrix and selection set of space solar satellites Given, the objective function can therefore be expressed as:
[0061] because Since it is a known quantity, it can be removed from the objective function when calculating the optimal beamforming vector. Similarly, it refers to space-based solar satellites. The equivalent channel response is formed by the channel response of the direct channel to the Mars probe and the channel of the IRS reflection link. Furthermore, let... The objective function can be rewritten as: ; The optimization problem described above is the Rayleigh quotient maximization problem, and its optimal solution lies in the matrix. In the direction of the principal eigenvector, therefore this scheme is effective for... Perform eigenvalue decomposition to obtain .in, For matrix eigenvectors, for eigenvalues.
[0062] Considering the constraints of the transmitter beamforming vector Using Rayleigh quotient theory, the optimal solution for the beamforming vector is obtained: ; in For matrix Maximum eigenvalue The corresponding feature vector.
[0063] Steps 3-5: Select a space-based solar-powered satellite for charging based on its power contribution.
[0064] Specifically, the IRS phase shift matrix and beamforming vector Given, the objective function can be written as: ; because Since it is a known quantity, it can be removed from the objective function when calculating the optimal beamforming vector. Indicates space-based solar satellite The received power of the emitted energy at the Mars probe. The selection of space solar satellite arrays and the space solar satellite arrays visible to the Mars probe at different times. They are different, therefore the variables are not omitted here. and The time index in the text.
[0065] The above constraint means that, among all the space solar satellites visible to the Mars probe, three space solar satellites that can receive the highest power will be selected for energy transfer.
[0066] Steps 3-6 return to step 3-2 until the Mars probe receives the ideal energy or the number of iterations reaches the upper limit.
[0067] Figure 3 The convergence of the alternative optimization algorithm proposed in this invention under different numbers of IRS reflective elements is presented. It can be seen that the alternative optimization algorithm can achieve stable convergence under different numbers of IRS reflective elements, and the convergence is fastest when the number of IRS reflective elements is 1600.
[0068] Figure 4 The time consumption of the proposed optimization algorithm varies with the number of IRS reflective elements. Figure 4 The results show that as the number of IRS reflectors increases from 1600 to 4900, the computation time of the proposed algorithm also increases from 0.4s to 1.3s, but remains within an acceptable range. Meanwhile, when the number of IRS reflectors is 2500, the channel gain reaches a relatively high 34dB, and the computation time is only 0.7s, achieving a balance between efficiency and complexity.
[0069] Figure 5 The invention presents a comparison of the total received energy as a function of the number of IRS reflective elements with two mechanisms: the IRS-assisted safe wireless charging method for Mars rovers proposed in this invention, and the IRS without IRS (w / o IRS) and the IRS with random phase shift (w / Rand. IRS). Figure 5 The results show that the total received energy obtained by the algorithm proposed in this invention far exceeds that of the other two mechanisms, and the performance is more stable.
[0070] Figure 6 This paper presents a comparison of the false detection rate (FDR) of the proposed IRS-assisted safe wireless charging method for Mars rovers with and without IRS and with Rand. IRS, as the number of IRS reflective elements varies. It can be seen that the deployment and optimization of the IRS effectively reduces the FDR and ensures the safety performance of the system.
[0071] Example: Without loss of generality, to achieve continuous 24 / 7 power supply, this embodiment employs seven Mars-Sun-synchronous orbital planes, each at an altitude of 550 km, and deploys seven space-based solar power satellites, each equipped with 16 antennas and 2500 IRS elements. In addition, a single-antenna legitimate Mars probe performs its mission on the Martian surface, while a single-antenna malicious Mars probe is positioned around the legitimate probe, attempting to impersonate it and receive energy transmitted from the space-based solar power satellites.
[0072] This embodiment assumes that each space solar satellite is equipped with an area of 1000m². 2 The solar panels have a conversion efficiency of 0.35. The space-based solar satellite uses a laser with a wavelength of 1064 micrometers to charge the Mars rover, emitting a maximum transmission power of 1,000,000 W. The efficiency of converting DC power to radio frequency (RF) signals is 0.85. The energy reflectivity of the RF signal after passing through the IRS reflector is 0.95, and the efficiency of converting the signal back to DC power at the Mars rover is 0.8. To ensure the safety of the wireless charging system, the false alarm rate threshold is set to 0.01, and the false negative rate threshold is set to 0.05.
[0073] In summary, the system of this invention can improve the charging efficiency of Mars probes while ensuring system access security. This invention first constructs a secure wireless charging model for Mars probes based on a space-based solar satellite and an IRS, and then establishes an objective function to maximize received energy. Next, an alternating optimization algorithm is used to solve this optimization problem. By decomposing the difficult original problem into three solvable sub-problems and iteratively optimizing these sub-problems, the system ultimately maximizes received energy while maintaining the false alarm rate and false negative rate within a safe range. This invention significantly improves received energy, reduces the false negative rate, and exhibits good stability.
[0074] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.
Claims
1. A wireless charging method for planetary probes based on intelligent reflective surfaces, characterized in that, include: Deploy a wireless charging system for the target planet, including multiple space solar satellites mounted on the target planet's geosynchronous orbit and an intelligent reflective surface (IRS) set on the target planet's surface; The target planet has planetary probes, including legitimate planetary probes and potentially malicious planetary probes; The space solar satellite employs an IRS-based challenge-response physical layer authentication mechanism to authenticate the receiver. Once the receiver is confirmed to be a legitimate planetary probe, the energy transfer phase begins. First, the beamforming vector and IRS phase shift matrix of the space solar satellite are jointly solved using an alternating optimization algorithm. Simultaneously, from the currently visible space solar satellites, the space solar satellite used for energy transfer is selected with the goal of maximizing the received energy of the legitimate planetary probe. Then, the transmit power and IRS phase of the space solar satellite are configured according to the beamforming vector and IRS phase shift matrix. Finally, the selected space solar satellite begins energy transfer, with a portion of the energy being directly absorbed via the space solar satellite-legitimate planetary probe direct link, and the other portion reaching the legitimate planetary probe via the IRS reflection link, thereby maximizing the received energy of the legitimate planetary probe.
2. The wireless charging method for planetary probes based on intelligent reflective surfaces according to claim 1, characterized in that, The space-based solar satellite employs an IRS-based challenge-response physical layer authentication mechanism to authenticate the receiver, which includes two phases: identity association and identity verification. During the identity verification phase, legitimate planetary probes send signals to space-based solar satellites. Sending a pilot signal, space solar satellite By activating all IRS phase configurations in turn, the received signals are detected and estimated, thereby constructing the channel response of a legitimate planetary probe under different configurations. This completes the identity verification process and forms the physical layer fingerprint information of the legitimate planetary probe. During the identity verification phase, the space-based solar satellite Randomly configuring IRS as a challenge; when space solar satellites Upon receiving a signal from a planetary probe, it uses its pre-stored channel response. With real-time received channel response Perform matching; if the signal originates from a legitimate planetary probe, the estimated channel response is: , For the identity verification phase of space solar satellites The estimation error at that point; if it originates from a malicious planetary probe, the estimated channel response is... , The channel response was forged by a malicious planetary probe.
3. The wireless charging method for planetary probes based on intelligent reflective surfaces according to claim 1, characterized in that, Malicious planetary probes spoofing channel responses Represented as: , Expressing expectations, For space-based solar satellites The equivalent channel response is formed by the channel response of the direct channel to the planetary probe and the channel of the IRS reflection link. For space-based solar satellites Channel response of the direct channel between the planetary probe and the probe; For space-based solar satellites To the IRS Channel response of each reflecting element; For the IRS Channel response from each reflector element to the planetary probe; Indicates random phase shift Statistical expectation; For the IRS Optimal phase offset configuration of each reflective element It is a natural constant. The imaginary unit, It is a collection of space-based solar-powered satellites.
4. The wireless charging method for planetary probes based on intelligent reflective surfaces according to claim 1, characterized in that, When verifying the identity of the launcher, the space solar satellite The currently estimated channel response Compared with previously stored channel responses Compare; define for: ； in As an identity indicator variable, This indicates that the launcher is a legitimate planetary probe. This indicates that the launcher is a malicious planetary probe; Based on this, the following two assumptions are made: Null hypothesis H0: It is assumed that the sender of the message is a legitimate planetary probe; Alternative hypothesis H1: It is assumed that the sender of the message is a malicious planetary probe; The verification result is denoted as... ,like If so, it indicates that the authentication has been successful; The generalized likelihood ratio test is used for calculation, based on the H0 assumption and the IRS phase shift matrix selected by the given space solar satellite. Test statistic It can be written as: This is used to measure the difference between the current channel response and the stored fingerprint; where This represents the IRS phase shift matrix selected for a given space solar satellite. Channel response of a legal planetary probe; This represents the variance of the additive white Gaussian noise; next, the test statistic is... With threshold The comparison and authentication rules are as follows: ； That is when At that time, the launcher was determined to be a legitimate planetary probe; Conversely, if the launcher does not meet the criteria, it is determined to be a malicious planetary probe.
5. The wireless charging method for planetary probes based on intelligent reflective surfaces according to claim 1, characterized in that, When a space-based solar satellite transmits energy to a planetary probe, the signal experiences free-space path loss. Molecular absorption loss and scattering caused by dust Transmission loss It can be represented as: ;in, For carrier frequency, This indicates the propagation delay of a signal from a space-based solar-powered satellite to a planetary probe; At any moment Space-based solar satellite The channel response of the direct channel between the planetary probe and the probe can be expressed as: ,in and These are space-based solar satellites Gain of the transmitting antenna in the direction of the planetary probe and gain of the receiving antenna in the space solar satellite Directional gain; space-based solar satellites To the IRS The channel response of a single reflecting element can be expressed as: ,in The reflectivity is the incident energy. For carrier wavelength, for Time Space Solar Satellite Location, For the IRS The position of each reflective element and For space-based solar satellites The upper transmitting antenna is in the IRS. Gain in the direction of each reflector and IRS A reflective element in a space solar satellite Gain in the direction of the transmitting antenna; IRS number Channel response from each reflecting element to the planetary probe: ,in and For the IRS The gain of each reflective element in the direction of the planetary probe and the receiving gain of the planetary probe; for The location of the planetary probe at any given time; Based on the above results, we can obtain Time Space Solar Satellite The emitted energy passes through the IRS. Cascaded channel response of a reflective element: And the equivalent channel response formed by the channel response of the direct channel and the channel of the IRS reflection link: ;in, IRS phase shift matrix The Middle The complex phase shift coefficient of each reflecting element, for Time IRS Phase shift of each reflective element; This leads to the development of space-based solar satellites. The received power of the emitted energy at the planetary probe is expressed as: ; where the parameter superscript This indicates the conjugate transpose. express Beamforming vector of a space-time solar satellite; Finally, we get Energy collected by the planetary probe: ； in ,when When, it means at Time Space Solar Satellite Selected for energy transfer This indicates that it was not selected; This indicates the efficiency with which radio frequency energy is converted into DC energy at the planetary probe after transmission; This refers to the time it takes for energy to transfer.
6. The wireless charging method for planetary probes based on intelligent reflective surfaces according to claim 1, characterized in that, When using an alternating optimization algorithm to jointly solve for the selection of space solar satellites, beamforming vectors, and IRS phase shift matrices, the objective function and constraints of the optimization problem are as follows: ； in, Indicates space-based solar satellite The choice of variables, express Beamforming vector of a space-based solar satellite at any given time. for Time IRS The complex phase shift coefficient of each reflecting element; for The selection of space-based solar satellites at any given time express A collection of space-based solar-powered satellites that are always visible to planetary probes; This is the maximum acceptable false negative threshold for the system.
7. The wireless charging method for planetary probes based on intelligent reflective surfaces according to claim 6, characterized in that, The optimization problem is solved by using an alternating optimization algorithm. By alternately optimizing the IRS phase shift matrix, the beamforming vector of the space solar satellite, and the selection strategy of the space solar satellite, the energy received by the planetary probe is maximized.
8. A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, When the processor executes the computer program, it implements the wireless charging method for planetary probes based on smart reflective surfaces as described in any one of claims 1-7.
9. A computer-readable storage medium storing a computer program; characterized in that, When the computer program is executed by the processor, it implements the wireless charging method for planetary probes based on smart reflective surfaces as described in any one of claims 1-7.