Inter-satellite link secure transmission method based on hybrid covert strategy

Abstract

The invention discloses an inter-satellite link secure transmission method based on a hybrid covert strategy, and belongs to the field of electronic communication. According to the invention, more randomness and friendly interference are introduced from three layers of a network layer, an MAC layer and a physical layer, and potential eavesdroppers are confused; in a network layer, a random routing unit is adopted, a plurality of routing paths meeting communication requirements are dynamically selected to replace a single optimal path, and a selection probability is distributed to each routing path according to routing metrics. In the MAC layer, the spectrum sharing technology is utilized to distribute less power for the information needing to be hidden, so that the signal detection probability is reduced, and the communication security is improved. In a physical layer, a rate division multiple access unit and a superposition coding technology are adopted, so that a plurality of users can efficiently share the same time-frequency resource at the same time. According to the invention, the communication efficiency can be improved, and the transmission randomness and complexity can be further improved, so that the communication security is enhanced.

Description

Technical Field

[0001] The invention relates to an inter-satellite link security transmission method based on a hybrid concealment strategy, and belongs to the field of electronic communications. Background Art

[0002] In the modern world of space exploration and global connectivity, intersatellite communication networks have become a critical infrastructure that enables seamless data exchange, powerful collaboration, and coordination of various space operations. As intersatellite communication networks continue to evolve and play a critical role in space missions, ensuring their security and integrity has become a primary challenge. The unique characteristics of intersatellite communications, such as predictable satellite motion and utilization of high-frequency bands, present three distinct challenges in protecting against potential threats, including interception, unauthorized access, and tampering. Due to the special nature of intersatellite communications, physical layer security and encryption technologies commonly used for communication network security face limitations. By hiding the presence of transmissions from potential adversaries, covert communications provide a strong defense against interception and unauthorized access, ensuring the confidentiality and integrity of sensitive data exchanged between satellites. Summary of the invention

[0003] In order to solve the problems of easy tracking and open access faced by existing intersatellite networks, the purpose of the present invention is to provide an intersatellite link security transmission method based on a hybrid concealment strategy. The present invention fully considers the unique characteristics of intersatellite communication and introduces more randomness and friendly interference from the three levels of network layer, MAC layer and physical layer to confuse potential eavesdroppers; at the network layer, the present invention adopts a random routing unit to dynamically select multiple routing paths that meet communication requirements instead of a single optimal path, and each routing path is assigned a selection probability according to the routing metric. The unpredictability of transmission is increased by randomly selecting paths, making it more difficult for attackers to determine the exact communication path. At the MAC layer, the present invention uses spectrum sharing technology to allocate less power to information that needs to be hidden to reduce the probability of signal detection, thereby improving the security of communication. This technology makes it difficult for attackers to detect transmitted signals, further enhancing the concealment of communication. At the physical layer, the present invention adopts rate division multiple access units and superposition coding technology to enable multiple users to efficiently share the same time-frequency resources at the same time. The present invention can not only improve the efficiency of communication, but also further increase the randomness and complexity of transmission, thereby enhancing the security of communication.

[0004] The objects of the present invention are achieved by the following methods.

[0005] The intersatellite link secure transmission method based on a hybrid concealment strategy disclosed in the present invention comprises the following steps:

[0006] Step 1: Based on the network connection topology, considering the LoS-dominated propagation environment and beam-focused link characteristics, simplify the selection of routing candidates and set two basic routing design rules; the rules are: first, when the administrator is located in the beam direction of the satellite transmitter, no routing is established; second, the signal is sent only when the communication distance of the nearby satellite receiver is shorter than the communication distance to the administrator. According to the rules, multiple routing paths that meet the communication requirements are selected;

[0007] Step 2: According to the communication requirements, select several routing paths that meet the conditions from the multiple routing paths designed in Step 1; then assign a selection probability to each routing path based on the routing metric. Finally, randomly select one of the paths to transmit information based on the selection probability;

[0008] The routing metrics include: latency, outages, costs, and history of potential eavesdropping or attacks;

[0009] Step 3: Make adaptive routing decisions based on real-time network status and demand. By monitoring the network status in real time, including satellite position, link quality, and communication load, adjust the path selection described in Step 2 in real time to perform covert information transmission.

[0010] Step 4: Based on the selected path, the rate division multiple access (RSMA) protocol is used to complete the covert signal transmission; the signal transmission process mainly includes superposition coding at the transmitter and power allocation at the receiver. The specific transmission process is as follows:

[0011] i. At the transmitting end, the data stream to be transmitted is divided into a public data stream and a private data stream. The public data stream adopts a broadcast transmission strategy, and the private data stream adopts a unicast-based spatial division multiple access SDMA transmission strategy.

[0012] ii. The transmitter uses superposition coding technology to superimpose the public data stream onto the private data stream to form a mixed data stream for transmission.

[0013] iii. At the receiving end, the serial interference cancellation (SIC) method is used to preferentially decode and eliminate the public data stream to reduce interference when decoding the private data stream.

[0014] iv. The receiving end dynamically adjusts the power allocation of public and private data streams according to channel conditions and user needs.

[0015] To achieve the best performance balance.

[0016] Beneficial effects:

[0017] 1. Enhanced communication concealment: By introducing more randomness and friendly interference at the network layer, MAC layer and physical layer, the present invention significantly increases the concealment of intersatellite communication. The use of random routing units, the application of spectrum sharing technology, and the application of rate division multiple access units and superposition coding technology make it difficult for potential eavesdroppers to track and detect communication signals, thereby significantly improving the security of communications.

[0018] 2. Improve the unpredictability of communication: Use a random path selection method to replace the traditional single optimal path communication, making it difficult for attackers to determine the exact communication path. This unpredictability makes communication more difficult to track and interfere with, improving the reliability and stability of communication.

[0019] 3. Optimize communication efficiency: The application of rate division multiple access unit and superposition coding technology enables multiple users to efficiently share the same time-frequency resources at the same time, thereby improving communication efficiency and throughput while optimizing the utilization of spectrum resources.

[0020] 4. Improve the adaptability of communication: The present invention can make adaptive routing decisions based on real-time network status and requirements, monitor network status in real time and adjust path selection to achieve the transmission of covert information. This adaptability makes communication more flexible and reliable, and can adapt to various complex network environments and requirements.

[0021] 5. Reduce communication risks: By introducing a hybrid concealment strategy, the present invention can reduce the risk of communication being intercepted and cracked. This strategy can not only increase the concealment and unpredictability of communication, but also further improve the security and reliability of communication by optimizing communication processes and resource allocation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Comparison of the detected performance between direct transmission and dynamically adjusted routing transmission. DETAILED DESCRIPTION

[0023] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0024] Embodiment 1:

[0025] like Figure 1 As shown, the inter-satellite link secure transmission method based on the hybrid concealment strategy disclosed in this embodiment has the following specific implementation steps:

[0026] Use the FPGA development board and VIVADO development tools to build the system environment. Then write programs on the FPGA chip including multiple functional modules such as position detection module, distance calculation module, path selection module and communication control.

[0027] The FPGA chip obtains satellite position information by connecting to the GP5MX1513F1 navigation chip, obtains link quality information by connecting to the signal strength sensor, and obtains communication load information by connecting to the data transmission module. Then, the adapter circuit is designed to connect these sensors to the FPGA chip, and the data acquisition and processing circuit is designed to process the sensor data. The state monitoring logic circuit performs state monitoring and updates based on the processed data. The controller interface circuit uses the respective communication protocols of the sensors (such as the NMEA 0183 protocol for satellite positioning sensors and the ITU-T G.99x series standards for link quality sensors) to transmit the monitored network status information to other modules.

[0028] Step 1: Route candidate selection

[0029] In view of the LoS propagation characteristics and beam focusing link characteristics in the satellite network, the present invention constructs a simplified route candidate selection mechanism.

[0030] In the location detection module at the PS end of the FPGA chip, the FPGA chip is connected to the GP5MX1513F1 navigation chip. The GP5MX1513F1 navigation chip receives satellite signals through the antenna unit, filters the signals, down-converts them, amplifies them, and performs a series of processing such as analog-to-digital conversion to obtain digital intermediate frequency signals, and then captures, tracks, synchronizes bits and frames the intermediate frequency signals, demodulates the navigation data, and finally calculates the user's latitude, longitude, altitude, speed, time and other information, packages them into data frames in the NMEA-0183 protocol format, and then outputs the data through the standard serial port. The hardware circuit generated by the NMEA-0183 protocol parsing module is embedded in the FPGA. On the one hand, it receives the serial data sent by the GP5MX1513F1 chip through the serial port module, and sends the received signal to the parsing module for processing. On the other hand, the parsing module extracts the required information according to the data format of the NMEA-0183 protocol, and then monitors the administrator's location information in real time.

[0031] Set the following two core routing design rules and specific implementation methods:

[0032] Rule 1: When the administrator is within the beam coverage of the satellite transmitter, no communication route is established.

[0033] Based on the location information detected by the location detection module, it is determined whether the administrator is within the coverage of the satellite transmission according to the preset beam coverage. If yes, the programming part on the PL side controls the communication module or signal transmission device to avoid establishing a communication route to reduce the risk of the administrator eavesdropping on the information.

[0034] Rule 2: Signal transmission is allowed only when the communication distance of the satellite receiver is shorter than the communication distance to the administrator.

[0035] In the distance calculation module on the PS side, the Euclidean distance between the administrator and the receiver is calculated based on the received location information. Then, through the path selection module, based on the calculated distance information of each possible path, the shortest path algorithm is used to determine the best path to ensure that the information reaches the target receiver via the shortest path, thereby reducing the possibility of information leakage.

[0036] According to the above rules and related operations, two bit stream files are generated and burned into the FLASH chip in advance. At the PS end, the rising edge of the two design-regulated flag information triggers an interrupt to achieve reconfigurable switching scheduling.

[0037] To quantify the above rules, the following mathematical expression is introduced:

[0038] Assume B beam is the beam coverage of the satellite transmitter, d admin is the distance from the administrator to the satellite transmitter, d receiver is the distance from the satellite receiver to the transmitter, D threshold is the communication distance threshold.

[0039] Rule 1 can be expressed mathematically as follows: If d admin ≤B beam , no route is established

[0040] Rule 2 can be expressed mathematically as follows: If d receiver <d admin And d receiver ≤D threshold , then the signal is sent based on the above rules. The present invention calculates and compares the d of different paths. admin and d receiver The routing candidates that meet the communication requirements are screened out and stored in the external memory FLASH.

[0041] The comparison of the detected performance between direct transmission and the transmission using the method to dynamically adjust the routing is shown in the attached figure. Figure 1 shown.

[0042] Step 2: Routing path selection and probability allocation

[0043] The route candidates stored in the FLASH are read, and the present invention selects a number of paths that meet the conditions according to the communication requirements. In order to enhance the unpredictability of transmission, the present invention adopts a probability selection mechanism based on route metrics.

[0044] Define the routing metric vector as M = [m1, m2, ..., m n ], where m irepresents the routing metric value of the i-th path, including delay, interruption probability, cost, and historical eavesdropping records. Then, the calculation unit inside the FPGA chip is used to perform the corresponding calculation to calculate the selection probability of each path. i Calculated by the following formula:

[0045]

[0046] Among them, α is an adjustment parameter used to control the sensitivity of route selection to the metric value. By adjusting the value of α, a balance can be achieved between routing security and efficiency.

[0047] In order to comprehensively consider multiple routing metrics, the present invention further introduces a weighted routing metric m′ i :

[0048]

[0049] Among them, w1, w2, w3, and w4 are the weights of each measurement item, which are adjusted according to the actual application scenario.

[0050] Next, a random number generator module is used to generate a random number, and then the calculation module is used to compare the calculated selection probability with the random number through a comparator, and a state machine is set to use the obtained size relationship as a state transition condition to determine the selected path. In addition, the present invention also introduces a routing selection strategy based on dynamic game, and designs a corresponding control logic module according to the PS end integration algorithm. By simulating the behavior of potential eavesdroppers, the communication status, path selection and other status information of each node in the system are monitored in real time, and dynamic adjustments are made according to pre-set strategies to dynamically adjust the routing selection to maximize the security of transmission.

[0051] Step 3: Adaptive routing decision and hidden information transmission

[0052] The present invention makes adaptive routing decisions based on real-time network status (including satellite position, link quality and communication load) and demand. The network status detection module collects and processes various sensor data and communication load information through AD, monitors network status such as satellite position, link quality and communication load in real time, and then the real-time routing decision module dynamically adjusts the path selected in Step 2 through the state machine according to the set utility function and constraints to maximize the efficiency and security of covert information transmission.

[0053] Let S t is the network state vector at time (t), R t is the routing decision vector at time t. The adaptive routing decision problem can be transformed into solving the following optimization problem:

[0054] maxRt Utility(St,Rt)stConstraints(St,Rt)

[0055] Among them, Utility(S t , R t ) is the utility function, which represents the performance of routing decision under given network conditions; Constraints(S t , R t ) are constraints, including communication requirements, resource limitations, etc.

[0056] Step 4: Based on the selected path, the rate division multiple access (RSMA) protocol is used to complete the covert signal transmission; the signal transmission process mainly includes superposition coding at the transmitter and power allocation at the receiver. The specific transmission process is as follows:

[0057] i. At the transmitting end, the data stream to be transmitted is divided into a public data stream and a private data stream, and the register is used to store the relevant parameter settings of the data stream division, and the QPSK data modulation module is configured to modulate the data stream into a signal suitable for transmission. The public data stream adopts a broadcast transmission strategy, and transmits the public data stream to all receiving ends through a broadcast module. The private data stream adopts a unicast-based spatial division multiple access SDMA transmission strategy.

[0058] ii. Superposition coding is implemented using logic circuits and controllers at the transmitter. The logic circuit adds the public data stream and the private data stream in a weighted manner according to the power allocation coefficient to form a mixed data stream. The controller is responsible for monitoring and managing the entire superposition coding process, including the setting of the power allocation coefficient and the processing of the data stream. The mathematical model of superposition coding can be expressed as:

[0059] Xmixed=Pcommon·Xcommon+Pprivate·Xprivate

[0060] Among them, P common and P private They are the power allocation coefficients for the public data flow and the private data flow, respectively, and are used to control the weights of the two in the mixed data flow.

[0061] iii. At the receiving end, the interference elimination module is set to use the serial interference elimination SIC method, through multiple decoder IP cores and interference eliminators, to preferentially decode and eliminate the public data stream to reduce the interference when decoding the private data stream. The decoder gradually decodes and eliminates different data streams through serial processing, and is configured according to the type and reception order of the data stream. At the same time, the parameters of the interference eliminator are set to ensure that the serial interference is effectively eliminated.

[0062] The signal-to-noise ratio (SNR) of the decoding process at the receiving end can be expressed as:

[0063]

[0064] Among them, h private and h common are the channel coefficients of private data stream and public data stream respectively, σ 2 is the noise power.

[0065] iv. The power allocation module at the receiving end communicates with the external hardware device power amplifier in real time according to channel conditions and user needs, and dynamically adjusts the power allocation of public data streams and private data streams to achieve the best performance balance.

[0066] The optimization problem of dynamic power allocation can be expressed as:

[0067]

[0068] Among them, Utility(P common , P private ) is the utility function, which represents the comprehensive performance of transmission efficiency and security; Constraints (P common , P private ) are constraints, including power limitation, channel conditions, etc.

[0069] By solving the above optimization problem, the optimal power allocation coefficient P can be obtained. common and P private , thereby achieving efficient and secure transmission of covert signals.

[0070] The main contents of the intersatellite link secure transmission method based on the hybrid concealment strategy described above can hide the concealed information through the system structure provided by the embodiment of the present invention, thereby achieving the purpose of improving transmission security. In actual application, some or all of the modules can be selected as needed to achieve the purpose of the scheme of this embodiment. Through the description of the above implementation methods, those skilled in the art can clearly understand the structure of the intersatellite link secure transmission method based on the hybrid concealment strategy.

Claims

1. A method for secure transmission of intersatellite links based on a hybrid concealment strategy, characterized in that: The following steps are included: Step 1: Based on the network connection topology, considering the LoS-dominated propagation environment and beam-focused link characteristics, simplify the selection of routing candidates and set two basic routing design rules; the rules are: first, when the administrator is located in the beam direction of the satellite transmitter, no routing is established; second, the signal is sent only when the communication distance of the nearby satellite receiver is shorter than the communication distance to the administrator; multiple routing paths that meet the communication requirements are selected according to the rules; Step 2: According to the communication requirements, select several routing paths that meet the conditions from the multiple routing paths designed in Step 1; then assign a selection probability to each routing path based on the routing metric; finally, randomly select one of the paths to transmit information based on the selection probability; The routing metrics include: latency, outages, costs, and history of potential eavesdropping or attacks; Step 3: Make adaptive routing decisions based on real-time network status and demand. By monitoring the network status in real time, including satellite position, link quality, and communication load, adjust the path selection described in Step 2 in real time to perform covert information transmission. Step 4: Based on the selected path, the rate division multiple access (RSMA) protocol is used to complete the covert signal transmission.

2. The intersatellite link secure transmission method based on a hybrid concealment strategy as claimed in claim 1, characterized in that: In Step 4, the concealed signal transmission process includes superposition coding at the transmitter and power allocation at the receiver. The specific transmission process is as follows: i. At the transmitting end, the data stream to be transmitted is divided into a public data stream and a private data stream; the public data stream adopts a broadcast transmission strategy, and the private data stream adopts a unicast-based spatial division multiple access SDMA transmission strategy; ii. The transmitter uses superposition coding technology to superimpose the public data stream onto the private data stream to form a mixed data stream for transmission; iii. At the receiving end, the serial interference cancellation SIC method is used to preferentially decode and eliminate the public data stream to reduce interference when decoding the private data stream; iv. The receiving end dynamically adjusts the power allocation of public and private data streams according to channel conditions and user needs. To achieve the best performance balance.

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