Anti-interception communication access method, system, device, storage medium and program product

Abstract

The application provides an anti-reconnaissance communication access method, system, device, storage medium and program product, and relates to the technical field of wireless communication networks.The method comprises the following steps: generating a radio frequency signal through an intelligent array antenna based on a time slot index and a beam power index, and sending the radio frequency signal to a satellite to obtain service data of a service copy package; the radio frequency signal comprises a transmission signal corresponding to each time slot, and each transmission signal carries a service copy package; within any two adjacent time slots, the intelligent array antenna adopts a wide beam mode and a high power mode to send the corresponding transmission signal in one time slot, and adopts a narrow beam mode and a low power mode to send the corresponding transmission signal in the other time slot. Through the above mode, the orthogonality of beams and power can be fully utilized to avoid the situation that the signal is detected by an electronic reconnaissance satellite, the performance of the aircraft against reconnaissance is improved, and the risk of exposure of the aircraft is reduced.

Description

Technical Field

[0001] This invention relates to the field of wireless communication network technology, and in particular to an anti-surveillance communication access method, system, device, storage medium, and program product. Background Technology

[0002] With the development of the low-altitude economy, applications such as drone logistics and low-altitude transportation are increasing, and the issue of low-altitude communication security is becoming increasingly prominent. Due to the rapid development of electronic reconnaissance satellite technology, the communication signals of low-altitude aircraft are easily intercepted and cracked by electronic reconnaissance satellites. Therefore, traditional communication access methods are difficult to cope with the detection of electronic reconnaissance satellites and cannot meet the requirements for communication security and stealth when aircraft swarm operations.

[0003] In existing technologies, aircraft mainly use CRDSA (Contention Resolution Diversity Slotted ALOHA) technology to access reconnaissance satellites, thereby sending service data to the reconnaissance satellites in the form of service copy packets. At the same time, high-orbit or low-orbit electronic reconnaissance satellites in the air are constantly reconnaissance of the aircraft's radio frequency signals (i.e., uplink access signals). When the power of the radio frequency signal detected by the electronic reconnaissance satellite exceeds the detection threshold, it is considered that the aircraft's communication signal has been successfully intercepted by the electronic reconnaissance satellite, and the covert communication between the aircraft and the reconnaissance satellite fails.

[0004] Reconnaissance satellites detect and receive the radio frequency (RF) signals of aircraft by detecting their energy density. Methods such as the Rayleigh detection method and the dual-threshold detection method both achieve communication between the aircraft and the reconnaissance satellite through signal energy density detection. For a single aircraft, if it uses a high-power RF signal, while this ensures its signal can be detected and received by the reconnaissance satellite, it is also easily detected by electronic reconnaissance satellites, resulting in a high risk of exposure. For an aircraft swarm, if multiple aircraft in the swarm transmit RF signals simultaneously, even if each aircraft uses a low-power RF signal, the superposition of signal energy from multiple aircraft at the same time can cause the total RF signal power of the swarm to exceed the detection threshold of the electronic reconnaissance satellite, resulting in a high risk of exposure for the entire swarm.

[0005] However, existing technologies lack communication access methods that can resist detection, so as to achieve covert communication between the aircraft and the detection satellite and ensure that the detection satellite can safely obtain the aircraft's operational data. Summary of the Invention

[0006] This invention provides an anti-surveillance communication access method, system, device, storage medium, and program product to address the lack of an anti-surveillance communication access method in the prior art, thereby enabling covert communication between aircraft and reconnaissance satellites and ensuring that reconnaissance satellites can securely acquire the operational data of aircraft.

[0007] This invention provides an anti-surveillance communication access method applied to an aircraft node. The aircraft node is equipped with a smart array antenna, comprising: generating a time slot index and a beam power index; the time slot index is used to identify each time slot of the aircraft node within an uplink communication time frame, and the beam power index is used to identify the beam mode and power mode adopted by the smart array antenna in each time slot; based on the time slot index and beam power index, a radio frequency (RF) signal is generated through the smart array antenna and transmitted to a satellite to enable the satellite to acquire service data of a service replica packet; wherein, the RF signal includes a transmission signal corresponding to each time slot, each transmission signal carries a service replica packet, and each service replica packet is generated based on the service data corresponding to the aircraft node; in any two adjacent time slots, the smart array antenna transmits the corresponding transmission signal in one time slot using a wide beam mode and a high power mode, and in the other time slot, the smart array antenna transmits the corresponding transmission signal using a narrow beam mode and a low power mode.

[0008] According to the anti-surveillance communication access method provided by the present invention, the wide beam mode is a mode in which the signal beamwidth of the smart array antenna is greater than a first preset threshold, the narrow beam mode is a mode in which the signal beamwidth of the smart array antenna is less than a second preset threshold, and the first preset threshold is greater than the second preset threshold; the high power mode is a mode in which the signal transmission power of the smart array antenna is greater than a third preset threshold, and the low power mode is a mode in which the signal transmission power of the smart array antenna is less than a fourth preset threshold, and the third preset threshold is greater than the fourth preset threshold.

[0009] According to the anti-surveillance communication access method provided by the present invention, the satellite acquires service data through the following steps: acquiring access signals; the access signals are radio frequency signals superimposed with Doppler frequency shift, communication interference, and receiver thermal noise; determining whether the current iteration count has reached the maximum iteration count; if the current iteration count has not reached the maximum iteration count, performing time-slot-by-time signal detection on the access signals to determine whether the current time slot of the access signals has reached the maximum time slot; if the current time slot of the access signals has not reached the maximum time slot, performing parameter estimation based on the number of active nodes in the current time slot and updating the current time slot; the number of active nodes is the total number of spacecraft nodes that have sent service copy packets in the current time slot; returning to the step of determining whether the current time slot of the access signals has reached the maximum time slot until the current time slot reaches the maximum time slot, updating the current iteration count; returning to the step of determining whether the current iteration count has reached the maximum iteration count until the current iteration count reaches the maximum iteration count, and obtaining service data.

[0010] According to the anti-surveillance communication access method provided by the present invention, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is at least two, then the current time slot is determined to be a dirty time slot; if there are known aircraft nodes in the dirty time slot, then frame reconstruction, parameter estimation, and physical layer waveform reconstruction are performed sequentially on the known aircraft nodes to obtain dirty time slot parameter estimation results; the known aircraft nodes are aircraft nodes whose corresponding service data has been decoded; based on the dirty time slot parameter estimation results, serial interference is removed from the access signal to obtain a de-interference signal; the de-interference signal is sequentially demodulated, deframed, and decoded to obtain the service data of the aircraft nodes.

[0011] According to the anti-surveillance communication access method provided by the present invention, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is one, the current time slot is determined to be a net time slot; the access signal is sequentially subjected to net time slot parameter estimation, demodulation processing, deframe processing and decoding processing to obtain the service data of the aircraft node.

[0012] According to the anti-surveillance communication access method provided by the present invention, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is zero, the current time slot is determined to be an empty time slot and no parameter estimation is performed.

[0013] This invention also provides an anti-surveillance communication access system, comprising: an index module for generating a time slot index and a beam power index; the time slot index is used to identify each time slot of the aircraft node within an uplink communication time frame, and the beam power index is used to identify the beam mode and power mode adopted by the intelligent array antenna in each time slot; an antenna signal output module for generating radio frequency (RF) signals through the intelligent array antenna based on the time slot index and the beam power index, and transmitting the RF signals to the satellite so that the satellite can acquire service data of the service copy packet; wherein, the RF signals include a transmission signal corresponding to each time slot, each transmission signal carries a service copy packet, and each service copy packet is generated based on the service data corresponding to the aircraft node; in any two adjacent time slots, the intelligent array antenna transmits the corresponding transmission signal in one time slot using a wide beam mode and a high power mode, and in another time slot, the intelligent array antenna transmits the corresponding transmission signal using a narrow beam mode and a low power mode.

[0014] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement any of the anti-surveillance communication access methods described above.

[0015] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements any of the anti-surveillance communication access methods described above.

[0016] The present invention also provides a computer program product, including a computer program that, when executed by a processor, implements any of the anti-surveillance communication access methods described above.

[0017] The anti-surveillance communication access method, system, device, storage medium, and program product provided by this invention involve setting up a smart array antenna at the spacecraft node. The smart array antenna can generate radio frequency (RF) signals based on time slot indices and beam power indices, and transmit these RF signals to the satellite. Since the RF signals include the transmission signals corresponding to each time slot in the uplink communication frame of the spacecraft node, and each transmission signal carries a service replica packet generated based on the service data corresponding to the spacecraft node, the satellite can obtain the service data of the service replica packet through the RF signals. Simultaneously, for any two adjacent time slots, the smart array antenna transmits the corresponding transmission signals using a wide beam mode and a high-power mode in one time slot, and uses a narrow beam mode and a low-power mode in the other time slot. That is, the two consecutive service replica packets of the spacecraft node can be transmitted using "wide beam mode superimposed with high-power mode" and "narrow beam mode superimposed with low-power mode," respectively. The aircraft employs a dual-mode access strategy, combining a narrow beam pattern with a low-power mode, to transmit signals to satellites. While this strategy results in highly directional but low-power signals, making it difficult for electronic reconnaissance satellites to detect the signal's power, the communication signal is less susceptible to interception, enabling covert communication between the aircraft and the satellite. Conversely, the "wide beam pattern with a high-power mode" strategy, while increasing signal power, suffers from shorter time slots, making it difficult for electronic reconnaissance satellites to reliably detect high-power signals within these short time slots. This dual-mode access strategy, alternating between "wide beam pattern with high-power mode" and "narrow beam pattern with low-power mode" in adjacent time slots, fully leverages the orthogonality of beam and power to prevent signal interception by electronic reconnaissance satellites, improving the aircraft's anti-interception performance and reducing the risk of exposure. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1This is one of the flowcharts of the anti-surveillance communication access method provided by the present invention.

[0020] Figure 2 This is a schematic diagram of an anti-surveillance satellite communication scenario provided by the present invention.

[0021] Figure 3 This is the second flowchart of the anti-surveillance communication access method provided by the present invention.

[0022] Figure 4 This is a schematic diagram of the satellite communication system provided by the present invention.

[0023] Figure 5 This is a schematic diagram of the anti-surveillance communication access system provided by the present invention.

[0024] Figure 6 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] Please see Figures 1 to 4 , Figure 1 This is one of the flowcharts illustrating the anti-surveillance communication access method provided by the present invention. Figure 2 This is a schematic diagram of an anti-surveillance satellite communication scenario provided by the present invention. Figure 3 This is the second flowchart illustrating the anti-surveillance communication access method provided by the present invention. Figure 4 This is a schematic diagram of the satellite communication system provided by the present invention. Figure 1 As shown, in this embodiment, the anti-surveillance communication access method is applied to an aircraft node. The aircraft node is equipped with a smart array antenna. The anti-surveillance communication access method includes steps S110 to S120, and the specific steps are as follows:

[0027] S110: Generate time slot index and beam power index.

[0028] The time slot index is used to identify each time slot of the aircraft node within the uplink communication frame, and the beam power index is used to identify the beam mode and power mode adopted by the smart array antenna in each time slot.

[0029] S120: Based on time slot index and beam power index, it generates radio frequency signals through a smart array antenna and sends the radio frequency signals to the satellite so that the satellite can obtain service data of the service copy packet.

[0030] The radio frequency signal includes the transmission signal corresponding to each time slot, each transmission signal carries a service replica packet, and each service replica packet is generated based on the service data corresponding to the aircraft node.

[0031] In any two adjacent time slots, the smart array antenna transmits the corresponding signal in one time slot using a wide beam mode and a high power mode, and in the other time slot, it transmits the corresponding signal in a narrow beam mode and a low power mode.

[0032] To facilitate understanding of the covert anti-surveillance satellite random access (CCWNS-CRDSA) method based on wide and narrow beamwidths of smart antennas proposed in this invention, this paper combines... Figure 2 and Figure 3 The application scenarios and application principles of the smart array antenna in this embodiment are explained.

[0033] like Figure 2 As shown, assuming the aircraft cluster includes a total of ( There are (positive integer) spacecraft nodes, denoted as... Each spacecraft node needs to be connected to a satellite (here and in the following text, "satellite" refers to a reconnaissance satellite, i.e.) Figure 2 The term "low-Earth orbit communication satellite" (to distinguish it from "electronic reconnaissance satellite") refers to a satellite that maintains communication with the spacecraft, transmitting its own operational data. Both the satellite and all spacecraft nodes share a unified time reference. Simultaneously, high-Earth orbit or low-Earth orbit electronic reconnaissance satellites continuously intercept the spacecraft's radio frequency signals (i.e., uplink access signals). When the power of the radio frequency signal detected by the electronic reconnaissance satellite exceeds a detection threshold, the spacecraft's communication signal is considered successfully intercepted, and the covert communication between the spacecraft and the receiving satellite fails.

[0034] For a single aircraft node In other words, when electronic reconnaissance satellites capture spacecraft nodes When the radio frequency signal exceeds the detection threshold, the spacecraft node is considered to be... Successfully detected by electronic reconnaissance satellite, spacecraft node Covert communication failure; For aircraft swarms, if multiple aircraft nodes in the swarm send radio frequency signals at the same time, the signal energy generated by the radio frequency signals of multiple aircraft nodes at the same time will be superimposed, which will cause the total power of the radio frequency signals of the aircraft swarm to exceed the detection threshold of the electronic reconnaissance satellite. This will undoubtedly increase the probability of the aircraft swarm being detected.

[0035] In existing technologies, a common approach to covert anti-reconnaissance is to reduce the radio frequency signal power of the spacecraft node. However, this reduces the success rate of the spacecraft node in accessing the satellite, because the reconnaissance satellite also detects and receives the radio frequency signal of the spacecraft node by detecting the energy density of the spacecraft node's radio frequency signal.

[0036] Based on this, this embodiment proposes a new covert anti-reconnaissance method, which sets up a smart array antenna at the aircraft node and uses different operating modes of the smart array antenna, namely, adjusting the beamwidth and transmit power of the smart array antenna to control the directivity of the radio frequency signal, and combines the multi-service replica packet access mechanism in CRDSA technology to achieve covert anti-reconnaissance of the aircraft node.

[0037] The smart array antenna has two basic operating modes: wide-beam mode and narrow-beam mode. In wide-beam mode, the beam gain is low, requiring increased signal transmission power to maintain communication link reliability; however, the wide beam makes satellite alignment easier for spacecraft nodes. In narrow-beam mode, the beam gain is high, allowing communication link reliability to be maintained even with lower signal transmission power; however, the narrow beam makes satellite alignment difficult for spacecraft nodes.

[0038] In CRDSA communication technology, for each spacecraft node, the satellite can divide each uplink communication time frame of that spacecraft node into... ( (a positive integer greater than 1) of length... The access time slot, that is, each uplink communication time frame of the spacecraft node includes There are 1 time slot, and the length of each time slot is 1. During uplink communication, the time slot index within the frame is used ( The time slot index indicates that it is used to identify each time slot of the aircraft node within the uplink communication frame.

[0039] If the first aircraft nodes If the spacecraft node needs to access the satellite and send its own service data to the satellite, then... Radio frequency signals can be generated according to the CRDSA communication mechanism and selected during uplink communication frames. ( It is a positive integer. Send service copy packets in 10 time slots.

[0040] It should be noted that the aircraft node Sent in an uplink communication frame Each service replica packet is generated based on the service data corresponding to the spacecraft node. That is, the service data carried by each service replica packet is the same, and the symbol vectors of all service replica packets are identical. They are all identical and can point out each other's positions.

[0041] Based on the characteristics of different operating modes of the aforementioned smart array antenna and the multi-service copy packet access mechanism in CRDSA technology, this embodiment proposes a dual-mode access strategy that alternates between "wide beam mode superimposed with high power mode" and "narrow beam mode superimposed with low power mode".

[0042] Specifically, if the aircraft nodes If the spacecraft node needs to access the satellite and send its own service data to the satellite, then... It can generate the time slot index of the current uplink communication frame. This provides an identifier basis for subsequent signal processing and generates a beam power index. Beam power index Used to determine the beam pattern and power mode that the smart array antenna uses in each time slot.

[0043] Furthermore, spacecraft nodes Based on the generated time slot index and beam power index Radio frequency (RF) signals are generated through a smart array antenna. These RF signals specifically include... One signal sent ; Send a signal in a time slot Carry a business copy package.

[0044] At the same time, the smart array antenna will index according to the beam power. Controlling the beam pattern and power mode used for signal transmission in different time slots: For each time slot, if the beam power index... The smart array antenna then transmits the corresponding signal in the wide beam mode and high power mode during that time slot; if the beam power index In this time slot, the smart array antenna transmits the corresponding signal using narrow beam mode and low power mode.

[0045] In this embodiment, within any two adjacent time slots of the uplink communication time frame, the smart array antenna transmits the corresponding transmission signal to the satellite in one time slot using a wide beam mode and a high power mode, and in the other time slot using a narrow beam mode and a low power mode.

[0046] It should be noted that when the spacecraft node When transmitting signals in a narrow-beam mode and a low-power mode in a certain time slot, the smart array antenna maintains communication link reliability even when transmitting signals in low-power mode due to the high beam gain and directivity of the narrow beam. The "narrow-beam mode superimposed with low-power mode" access strategy not only ensures the success rate of spacecraft node access to the satellite, but also effectively reduces the probability of spacecraft nodes and spacecraft clusters being detected because the narrow beam itself has more concentrated energy, making it difficult to reach the power detection threshold of electronic reconnaissance satellites.

[0047] However, the access strategy of "narrow beam mode superimposed with low power mode" has an "alignment" problem in the scenario of spacecraft node accessing low-Earth orbit satellites: the narrow beam has high directivity, which requires the spacecraft node to have high accuracy in satellite pointing error. However, due to the high speed of spacecraft node and satellite movement and rapid topology changes, the use of narrow beam will make it difficult for spacecraft node to align with satellites.

[0048] To avoid situations where satellites fail to accurately receive service copy packets due to difficulties in satellite alignment when using the "narrow beam mode superimposed with low power mode" access strategy, it is necessary to alternate between the "wide beam mode superimposed with high power mode" and "narrow beam mode superimposed with low power mode" access strategies in different time slots.

[0049] It should be noted that when the spacecraft node When transmitting corresponding signals in a wide-beam mode and high-power mode in a certain time slot, the spacecraft node can easily align with the satellite due to the sufficient beam width, thus avoiding the situation where the satellite fails to accurately receive the service copy packet due to the difficulty of the spacecraft node aligning with the satellite. In addition, although this access strategy increases the power of the transmitted signal, the time of a single time slot is relatively short, making it difficult for electronic reconnaissance satellites to detect high-power transmitted signals in a timely and stable manner in such a short time slot.

[0050] For a single aircraft node, the access strategy of "wide beam mode superimposed with high power mode" can ensure easy alignment, while the access strategy of "narrow beam mode superimposed with low power mode" can achieve covert anti-reconnaissance.

[0051] For aircraft swarms, in one time slot, one group of aircraft nodes uses an access strategy of "wide beam mode superimposed with high power mode" to send service replica packets, while another group of aircraft nodes uses an access strategy of "narrow beam mode superimposed with low power mode" to send service replica packets. In the next time slot, the access strategies used by the two groups of aircraft nodes are swapped. This mechanism can make full use of the orthogonality of beam and power to avoid the superposition of signal energy from multiple aircraft nodes, thereby avoiding the situation where the signal of the aircraft swarm can be intercepted by electronic reconnaissance satellites, reducing the overall detection probability of the aircraft swarm, improving the anti-reconnaissance performance of the aircraft swarm, and reducing the risk of exposure of the aircraft swarm.

[0052] The anti-surveillance communication access method provided in this embodiment involves setting up a smart array antenna at the spacecraft node. The smart array antenna can generate radio frequency (RF) signals based on time slot indices and beam power indices, and transmit these RF signals to the satellite. Since the RF signals include the transmission signals corresponding to each time slot in the uplink communication frame of the spacecraft node, and each transmission signal carries a service replica packet generated based on the service data corresponding to the spacecraft node, the satellite can obtain the service data of the service replica packet through the RF signals. Simultaneously, for any two adjacent time slots, the smart array antenna transmits the corresponding transmission signals using a wide beam mode and a high-power mode in one time slot, and uses a narrow beam mode and a low-power mode in the other time slot. That is, the two consecutive service replica packets of the spacecraft node can be transmitted using "wide beam mode superimposed with high-power mode" and "narrow beam mode superimposed with low-power mode," respectively. The dual-mode access strategy transmits signals to the satellite in two ways. When using the "narrow beam mode superimposed with low power mode" access strategy, the transmitted signal has high directivity and low power, making it difficult to reach the power detection threshold of electronic reconnaissance satellites. Therefore, the communication signal is not easily intercepted by electronic reconnaissance satellites, enabling covert communication between the spacecraft and the receiving satellite. When using the "wide beam mode superimposed with high power mode" access strategy, although the transmitted signal power is increased, the time slot of a single time slot is too short. It is difficult for electronic reconnaissance satellites to detect high-power transmitted signals in a timely and stable manner within such a short time slot. This dual-mode access strategy, which alternates between "wide beam mode superimposed with high power mode" and "narrow beam mode superimposed with low power mode" in adjacent time slots, can make full use of the orthogonality of beam and power to avoid the signal being intercepted by electronic reconnaissance satellites, thereby improving the spacecraft's anti-interception performance and reducing the risk of the spacecraft being exposed.

[0053] In some embodiments, the wide beam mode is a mode in which the signal beamwidth of the smart array antenna is greater than a first preset threshold, and the narrow beam mode is a mode in which the signal beamwidth of the smart array antenna is less than a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; the high power mode is a mode in which the signal transmission power of the smart array antenna is greater than a third preset threshold, and the low power mode is a mode in which the signal transmission power of the smart array antenna is less than a fourth preset threshold, wherein the third preset threshold is greater than the fourth preset threshold.

[0054] In some embodiments, the satellite acquires service data through the following steps: acquiring access signals; the access signals are radio frequency signals superimposed with Doppler frequency shift, communication interference, and receiver thermal noise; determining whether the current iteration count has reached the maximum iteration count; if the current iteration count has not reached the maximum iteration count, performing time-slot-by-time signal detection on the access signals to determine whether the current time slot of the access signals has reached the maximum time slot; if the current time slot of the access signals has not reached the maximum time slot, performing parameter estimation based on the number of active nodes in the current time slot and updating the current time slot; the number of active nodes is the total number of spacecraft nodes that have sent service replica packets in the current time slot; returning to the step of determining whether the current time slot of the access signals has reached the maximum time slot until the current time slot reaches the maximum time slot, updating the current iteration count; returning to the step of determining whether the current iteration count has reached the maximum iteration count until the current iteration count reaches the maximum iteration count, and obtaining service data.

[0055] Understandably, after a spacecraft node accesses its communication channel with a satellite and transmits radio frequency signals to the satellite, it may be affected by external interference signals during data transmission. This interference can cause Doppler shift, interference from other users, and receiver thermal noise to be superimposed on the wireless channel. Therefore, the radio frequency signal inevitably undergoes waveform distortion during data transmission, which in turn affects the actual access signal acquired by the satellite. It is a radio frequency signal superimposed with Doppler frequency shift, communication interference and receiver thermal noise.

[0056] Due to the actual access signal collected by the satellite It is a radio frequency signal superimposed with Doppler frequency shift, communication interference and receiver thermal noise. The waveform has been distorted, resulting in signal distortion. Therefore, the satellite, as the receiving and processing end, needs to perform additional time-slot signal detection and parameter estimation to extract the service data of the spacecraft node.

[0057] Specifically, such as Figure 3 As shown, initialize the current iteration number. This sets the initial state for subsequent iterations; then the iteration process begins, with the current iteration number... Add 1, that is (Here, "=" indicates assignment), and determine the current iteration number. Has the maximum number of iterations been reached? (An uplink communication time frame includes) (time slot).

[0058] If the current iteration number Maximum number of iterations not reached Then, time-slot-by-time signal detection is performed on the access signal to determine whether the current time slot of the access signal has reached the maximum time slot.

[0059] If the current time slot of the access signal has not reached the maximum time slot, then parameter estimation is performed based on the number of active nodes in the current time slot to obtain the characteristics and channel-related parameters of the current time slot signal, and the current time slot is updated (i.e., entering the next time slot).

[0060] It should be noted that since there may be more than one airborne vehicle node, and different airborne vehicle nodes may send their own service copy packets to the satellite simultaneously in the same time slot, in this embodiment, the airborne vehicle node that has sent its own service copy packet in the current time slot is regarded as an active node, and the airborne vehicle node that has not sent its own service copy packet in the current time slot is regarded as a silent node. The number of active nodes is the total number of airborne vehicle nodes that have sent service copy packets in the current time slot, and the number of silent nodes is the total number of airborne vehicle nodes that have not sent service copy packets in the current time slot.

[0061] Furthermore, the process returns to the step of determining whether the current time slot of the access signal has reached the maximum time slot, and continues until the current time slot reaches the maximum time slot, completing one round of iteration processing, and updating the current iteration number. Add 1.

[0062] Further, return to the step of determining whether the current iteration count has reached the maximum iteration count, until the current iteration count reaches the maximum iteration count, and obtain the business data.

[0063] Understandably, if the current iteration number Reaching the maximum number of iterations If the signal is detected, it means that the transmission signal of each time slot in the current uplink communication time frame has been detected. At this time, the next uplink communication time frame can be entered to continue the reception and processing of radio frequency signals.

[0064] In some embodiments, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is at least two, then the current time slot is determined to be a dirty time slot; if there are known aircraft nodes in the dirty time slot, then frame reconstruction, parameter estimation, and physical layer waveform reconstruction are performed sequentially on the known aircraft nodes to obtain dirty time slot parameter estimation results; the known aircraft nodes are aircraft nodes whose corresponding service data has been decoded; based on the dirty time slot parameter estimation results, serial interference is removed from the access signal to obtain a de-interference signal; the de-interference signal is sequentially demodulated, deframed, and decoded to obtain the service data of the aircraft nodes.

[0065] Specifically, for each current time slot, the number of active nodes in the current time slot is first calculated. .

[0066] If the number of active nodes in the current time slot There must be at least two, that is If the current time slot is determined to be a dirty time slot, the satellite will query the time slot index of the known spacecraft nodes to further determine whether there are known spacecraft nodes in the dirty time slot. The known spacecraft nodes are the spacecraft nodes whose corresponding service data has been decoded (i.e., known users).

[0067] If there is no known spacecraft node in the dirty time slot, the next time slot can be entered directly.

[0068] If a known aircraft node exists within a dirty time slot, then perform MAC (Media Access Control) layer frame reconstruction, parameter estimation, and physical layer waveform reconstruction sequentially on the known aircraft node to obtain the dirty time slot parameter estimation result.

[0069] Specifically, different active nodes simultaneously send their own service copy packets to the satellite in the same time slot. The service copy packets in the same time slot will cause serial interference to each other. However, if there is a known aircraft node among these active nodes, since the known aircraft node is the aircraft node whose corresponding service data has been decoded, the service copy packet of the known aircraft node in the current time slot can be directly removed, thereby eliminating the serial interference caused by the known aircraft node.

[0070] Since the service copy packets of a known aircraft node can be directly extracted from its preceding and following time slots, after MAC layer frame reconstruction of the known aircraft node, the preceding and following time slots of the known aircraft node can be combined to perform maximum likelihood parameter estimation and physical layer waveform reconstruction, identify the serial interference that can be eliminated, and obtain dirty time slot parameter estimation results.

[0071] Furthermore, based on the dirty time slot parameter estimation results, serial interference removal is performed on the access signal to eliminate the waveform signals of known aircraft nodes and obtain the de-interference signal. The de-interference signal is the signal with serial interference eliminated. The de-interference signal is then subjected to demodulation, deframe processing and decoding processing in sequence to obtain the service data of the aircraft node.

[0072] In some embodiments, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is one, then the current time slot is determined to be a net time slot; net time slot parameter estimation, demodulation processing, deframe processing and decoding processing are performed sequentially on the access signal to obtain the service data of the aircraft node.

[0073] Specifically, for each current time slot, the number of active nodes in the current time slot is first calculated. .

[0074] If the number of active nodes in the current time slot For one, that is If so, the current time slot is determined to be the net time slot.

[0075] Since no other aircraft nodes generate serial interference within the net time slot, the access signal can be directly subjected to net time slot parameter estimation, demodulation, deframe processing, and decoding processing sequentially to obtain the aircraft node's service data (i.e., Figure 3 and Figure 4 (The result of decoding the business data in the middle).

[0076] In some embodiments, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is zero, then the current time slot is determined to be an empty time slot and no parameter estimation is performed.

[0077] For ease of understanding, this section combines... Figure 4 The communication principle of this invention will be further explained.

[0078] like Figure 4 As shown, a cluster of spacecraft nodes and satellites can form a communication system. In this embodiment, the satellites do not require hardware modifications, while the spacecraft nodes need to be equipped with smart array antennas. The spacecraft cluster includes... There are 1 aircraft node, denoted as _____. Since the structure and principle of each spacecraft node are the same, for ease of understanding, only the first node will be discussed here. aircraft nodes Let's take an example to illustrate.

[0079] Aircraft Node The CRDSA array antenna transmission unit can fully reuse the traditional CRDSA algorithm. This unit includes a service data input module, a MAC layer framing module, an encoding and modulation module, an access timing control module, an access pattern generation module, and an antenna control and signal output module.

[0080] In the business data input module, the symbol vector of the business replica package It is temporarily stored in the business queue.

[0081] After the service data in the service queue enters the MAC layer for framing, the service data will be organized into a CRDSA frame structure.

[0082] The encoding and modulation module can encode and modulate the service data after framing to generate service copy packets.

[0083] The access timing control module generates access patterns through timing control. (i.e., slot index) and beam power index and determine The index number of each time slot; the access pattern generation module works with the RF gating to control the transmission time and mode of the RF signal; beam power index. In conjunction with a smart array antenna, it controls the beam and power mode of the transmitted signal.

[0084] The antenna control and signal output module is used to generate radio frequency (RF) signals and output them to the multi-user access channel. The expression for the RF signal is:

[0085] ;

[0086] in, Defined as: in time slot aircraft node Generate wide-beam transmission signal Wide beam transmission signal signal power For high power; Defined as: in time slot In other time slots, spacecraft nodes Generate narrow beam transmission signal Narrow beam signal transmission signal power It is for low power.

[0087] On the satellite side, the satellite is equipped with an onboard multi-user CRDSA access processing unit, which can fully reuse the traditional CRDSA algorithm. This unit includes a time-slot-by-time signal detection module, a net time slot judgment and processing module, a multi-user iterative serial interference removal module, and a known user optimal ranging and velocity measurement module.

[0088] The time-slot-by-time signal detection module is used to perform time-slot-by-time signal detection for multiple users (i.e., multiple aircraft nodes).

[0089] The net timeslot determination and processing module is used to determine whether the current timeslot of the access signal is a net timeslot. If it is a net timeslot, the net timeslot parameter is estimated, and demodulation, deframe processing and decoding are performed in sequence to obtain the service data decoding result. If it is not a net timeslot, it enters other processing procedures such as interference removal.

[0090] The multi-user iterative serial interference removal module is used for MAC frame reconstruction of known users, maximum likelihood parameter estimation based on the time slots before and after known users, and physical layer waveform reconstruction of known users. It also includes a SIC (Serial Interference Cancellation Module) module to achieve effective processing and interference removal of multi-user signals.

[0091] Optionally, to improve the accuracy of satellite side wave parameter estimation, multiple service copy packets (e.g., 3 to 4) can be used simultaneously to construct a time-series Kalman filter and conduct joint channel estimation.

[0092] Optionally, artificial intelligence technologies such as reinforcement learning can be used to further reduce serial interference among multiple users.

[0093] The anti-surveillance communication access method provided in this embodiment has at least the following advantages compared with the prior art:

[0094] (1) Significantly improved concealment: Under the condition that the communication success rate is basically the same as that of traditional CRDSA technology, it can significantly improve the anti-reconnaissance performance of single aircraft nodes and aircraft clusters, and can meet the needs of satellite covert communication.

[0095] (2) Strong hardware feasibility: The intelligent array antenna technology is relatively mature and does not require reconstruction of the communication protocol, and can be adapted to existing aircraft platforms.

[0096] (3) Strong system compatibility: No need to modify the existing onboard multi-user CRDSA access processing unit of the satellite, only need to set up a smart array antenna at the spacecraft node, and the hardware improvement cost is low.

[0097] This invention also provides an anti-surveillance communication access system. Please refer to [link / reference]. Figure 5 , Figure 5 This is a schematic diagram of the anti-surveillance communication access system provided by the present invention. In this embodiment, the anti-surveillance communication access system includes an index module 510 and an antenna signal output module 520.

[0098] Index module 510 is used to generate time slot indexes and beam power indexes.

[0099] The time slot index is used to identify each time slot of the aircraft node within the uplink communication frame, and the beam power index is used to identify the beam mode and power mode adopted by the smart array antenna in each time slot.

[0100] The antenna signal output module 520 is used to generate radio frequency signals based on time slot index and beam power index through a smart array antenna, and send the radio frequency signals to the satellite so that the satellite can obtain service data of the service copy packet.

[0101] The radio frequency signal includes the transmission signal corresponding to each time slot, each transmission signal carries a service replica packet, and each service replica packet is generated based on the service data corresponding to the aircraft node.

[0102] In any two adjacent time slots, the smart array antenna transmits the corresponding signal in one time slot using a wide beam mode and a high power mode, and in the other time slot, it transmits the corresponding signal in a narrow beam mode and a low power mode.

[0103] In some embodiments, the wide beam mode is a mode in which the signal beamwidth of the smart array antenna is greater than a first preset threshold, and the narrow beam mode is a mode in which the signal beamwidth of the smart array antenna is less than a second preset threshold, wherein the first preset threshold is greater than the second preset threshold; the high power mode is a mode in which the signal transmission power of the smart array antenna is greater than a third preset threshold, and the low power mode is a mode in which the signal transmission power of the smart array antenna is less than a fourth preset threshold, wherein the third preset threshold is greater than the fourth preset threshold.

[0104] In some embodiments, the satellite acquires service data through the following steps: acquiring access signals; the access signals are radio frequency signals superimposed with Doppler frequency shift, communication interference, and receiver thermal noise; determining whether the current iteration count has reached the maximum iteration count; if the current iteration count has not reached the maximum iteration count, performing time-slot-by-time signal detection on the access signals to determine whether the current time slot of the access signals has reached the maximum time slot; if the current time slot of the access signals has not reached the maximum time slot, performing parameter estimation based on the number of active nodes in the current time slot and updating the current time slot; the number of active nodes is the total number of spacecraft nodes that have sent service replica packets in the current time slot; returning to the step of determining whether the current time slot of the access signals has reached the maximum time slot until the current time slot reaches the maximum time slot, updating the current iteration count; returning to the step of determining whether the current iteration count has reached the maximum iteration count until the current iteration count reaches the maximum iteration count, and obtaining service data.

[0105] In some embodiments, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is at least two, then the current time slot is determined to be a dirty time slot; if there are known aircraft nodes in the dirty time slot, then frame reconstruction, parameter estimation, and physical layer waveform reconstruction are performed sequentially on the known aircraft nodes to obtain dirty time slot parameter estimation results; the known aircraft nodes are aircraft nodes whose corresponding service data has been decoded; based on the dirty time slot parameter estimation results, serial interference is removed from the access signal to obtain a de-interference signal; the de-interference signal is sequentially demodulated, deframed, and decoded to obtain the service data of the aircraft nodes.

[0106] In some embodiments, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is one, then the current time slot is determined to be a net time slot; net time slot parameter estimation, demodulation processing, deframe processing and decoding processing are performed sequentially on the access signal to obtain the service data of the aircraft node.

[0107] In some embodiments, parameter estimation is performed based on the number of active nodes in the current time slot, including: if the number of active nodes in the current time slot is zero, then the current time slot is determined to be an empty time slot and no parameter estimation is performed.

[0108] The present invention also provides an electronic device. Figure 6 This is a schematic diagram of the structure of the electronic device provided by the present invention, such as... Figure 6 As shown, the electronic device may include a processor 610, a communications interface 620, a memory 630, and a communication bus 640. The processor 610, communications interface 620, and memory 630 communicate with each other via the communication bus 640. The processor 610 can call logical instructions from the memory 630 to execute an anti-surveillance communication access method.

[0109] Furthermore, the logical instructions in the aforementioned memory 630 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0110] The present invention also provides a non-transitory computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the anti-surveillance communication access method provided by the above methods.

[0111] The present invention also provides a computer program product, which includes a computer program that can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the anti-surveillance communication access method provided by the above methods.

[0112] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0113] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention 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; and these 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 the present invention.

Claims

1. A method for anti-surveillance communication access, characterized in that, Applied to aircraft nodes, the aircraft nodes are equipped with smart array antennas, including: Generate a time slot index and a beam power index; the time slot index is used to identify each time slot of the aircraft node in the uplink communication time frame, and the beam power index is used to identify the beam mode and power mode adopted by the smart array antenna in each time slot; Based on the time slot index and the beam power index, a radio frequency signal is generated through the smart array antenna and transmitted to the satellite so that the satellite can obtain the service data of the service copy packet; The radio frequency signal includes a transmission signal corresponding to each time slot, each transmission signal carries a service replica packet, and each service replica packet is generated based on the service data corresponding to the spacecraft node. In any two adjacent time slots, the smart array antenna transmits the corresponding transmission signal in one time slot using a wide beam mode and a high power mode, and in the other time slot, the smart array antenna transmits the corresponding transmission signal in a narrow beam mode and a low power mode.

2. The anti-surveillance communication access method according to claim 1, characterized in that, The wide beam mode is a mode in which the signal beamwidth of the smart array antenna is greater than a first preset threshold, and the narrow beam mode is a mode in which the signal beamwidth of the smart array antenna is less than a second preset threshold, wherein the first preset threshold is greater than the second preset threshold. The high-power mode is when the signal transmission power of the smart array antenna is greater than a third preset threshold, and the low-power mode is when the signal transmission power of the smart array antenna is less than a fourth preset threshold, wherein the third preset threshold is greater than the fourth preset threshold.

3. The anti-surveillance communication access method according to claim 1, characterized in that, The satellite acquires the service data through the following steps: Acquire access signals; the access signals are the radio frequency signals superimposed with Doppler frequency shift, communication interference, and receiver thermal noise. Determine if the current iteration count has reached the maximum iteration count; If the current iteration count has not reached the maximum iteration count, then the access signal is subjected to time-slot-by-time signal detection to determine whether the current time slot of the access signal has reached the maximum time slot. If the current time slot of the access signal has not reached the maximum time slot, then the parameters are estimated based on the number of active nodes in the current time slot, and the current time slot is updated; the number of active nodes is the total number of aircraft nodes that have sent the service replica packet in the current time slot. Return to the step of determining whether the current time slot of the access signal has reached the maximum time slot, until the current time slot reaches the maximum time slot, and update the current iteration number; Return to the step of determining whether the current iteration count has reached the maximum iteration count, until the current iteration count reaches the maximum iteration count, and obtain the business data.

4. The anti-surveillance communication access method according to claim 3, characterized in that, The parameter estimation based on the number of active nodes in the current time slot includes: If the number of active nodes in the current time slot is at least two, then the current time slot is determined to be a dirty time slot. If a known aircraft node exists in the dirty time slot, then frame reconstruction, parameter estimation, and physical layer waveform reconstruction are performed sequentially on the known aircraft node to obtain the dirty time slot parameter estimation result; the known aircraft node is the aircraft node whose corresponding service data has been decoded. Based on the dirty time slot parameter estimation results, serial interference is removed from the access signal to obtain a de-interference signal; The interference-removed signal is sequentially demodulated, deframed, and decoded to obtain the service data of the aircraft node.

5. The anti-surveillance communication access method according to claim 3, characterized in that, The parameter estimation based on the number of active nodes in the current time slot includes: If the number of active nodes in the current time slot is one, then the current time slot is determined to be a net time slot; The access signal is sequentially subjected to net time slot parameter estimation, demodulation, deframe processing, and decoding to obtain the service data of the aircraft node.

6. The anti-surveillance communication access method according to claim 3, characterized in that, The parameter estimation based on the number of active nodes in the current time slot includes: If the number of active nodes in the current time slot is zero, then the current time slot is determined to be an empty time slot, and no parameter estimation is performed.

7. An anti-surveillance communication access system, characterized in that, include: An index module is used to generate a time slot index and a beam power index; the time slot index is used to identify each time slot of the aircraft node within the uplink communication time frame, and the beam power index is used to identify the beam mode and power mode adopted by the smart array antenna in each time slot; The antenna signal output module is used to generate a radio frequency signal based on the time slot index and the beam power index through the smart array antenna, and send the radio frequency signal to the satellite so that the satellite can obtain the service data of the service copy packet; The radio frequency signal includes a transmission signal corresponding to each time slot, each transmission signal carries a service replica packet, and each service replica packet is generated based on the service data corresponding to the spacecraft node. In any two adjacent time slots, the smart array antenna transmits the corresponding transmission signal in one time slot using a wide beam mode and a high power mode, and in the other time slot, the smart array antenna transmits the corresponding transmission signal in a narrow beam mode and a low power mode.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the anti-surveillance communication access method as described in any one of claims 1 to 6.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the anti-surveillance communication access method as described in any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the anti-surveillance communication access method as described in any one of claims 1 to 6.

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