Satellite two-way safety communication method based on signal constellation splitting and superposition

Abstract

The invention belongs to the field of satellite two-way security communication, and particularly discloses a satellite two-way security communication method based on signal constellation splitting and superposition, comprising the following steps: generating a first sending signal and a second sending signal, the real part of the signal bearing privacy information of a user, and the imaginary part bearing artificial noise; the signals are preprocessed to compensate channel responses when the signals are transmitted to the relay node through the first channel and the second channel respectively, so that real parts of the two sent signals have the same coefficient at the relay node; extracting real parts of the two signals, discarding imaginary parts of the two signals, and superposing the two extracted real part signals to form a mixed signal; forwarding the mixed signal to a corresponding user; and demodulating the real part signal of the signal sent by the opposite-end user from the received mixed signal according to the known real part and channel information of the signal sent by the opposite-end user so as to realize information transmission. According to the invention, the embedding of the artificial noise and the constellation superposition can be realized in the single time slot, and the communication security is ensured.

Description

Technical Field

[0001] This application belongs to the field of satellite two-way secure communication, and more specifically, relates to a satellite two-way secure communication method based on signal constellation splitting and superposition. Background Technology

[0002] Satellites, acting as relay nodes, amplify or forward received signals, compensating for attenuation and loss during propagation. This plays a crucial role in improving the reliability and quality of satellite communication. Two-way satellite relay communication is a communication method based on relay technology, where both communicating parties achieve bidirectional data transmission through satellite relay nodes. Unlike traditional one-way relay communication, two-way satellite relay communication not only allows one user to send information to another but also allows two users to simultaneously transmit information to each other, using relay nodes to forward signals and further improving transmission efficiency. However, on the one hand, not every relay node in a satellite network is completely trustworthy; some relays may intentionally or unintentionally monitor or steal user information. On the other hand, due to the open nature of wireless communication, other users in the network may also intercept information. Therefore, researching secure transmission mechanisms that can simultaneously resist internal and external eavesdropping is particularly important.

[0003] Currently, constellation superposition combined with artificial noise technology is the mainstream method to combat the aforementioned internal and external eavesdropping. The basic principle of this approach is that users embed specific forms of artificial noise in two consecutive time slots, causing the information from both users to overlap in the signal received by the untrusted relay, making it impossible to analyze individually. Simultaneously, due to the randomness of the channel, the artificial noise continuously interferes with the eavesdropper's received signal. However, this approach requires two transmission time slots to complete the artificial noise embedding and constellation superposition operations, significantly reducing transmission efficiency in communication systems where a single time slot is the primary transmission unit. Therefore, how to achieve artificial noise embedding and constellation superposition within a single time slot while ensuring communication security is a pressing problem that needs to be solved.

[0004] Therefore, how to embed artificial noise and superimpose constellations within a single time slot while ensuring communication security is an urgent problem to be solved. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a satellite two-way secure communication method based on signal constellation splitting and superposition, which can achieve the embedding of artificial noise and constellation superposition within a single time slot while ensuring communication security.

[0006] To achieve the above objectives, in a first aspect, this application provides a satellite two-way secure communication method based on signal constellation splitting and superposition, comprising the following steps: S10, generate a first transmission signal and a second transmission signal. The real part of the first transmission signal carries the privacy information of the first user, and the imaginary part carries the first artificial noise. The real part of the second transmission signal carries the privacy information of the second user, and the imaginary part carries the second artificial noise. S20, preprocess the first and second transmitted signals to compensate for their channel response when they are transmitted to the relay node via the first and second channels respectively, so that the real part of the first and second transmitted signals have the same coefficient at the relay node. S30: Receive the preprocessed first and second transmission signals, extract the real parts of the two signals and discard their imaginary parts, and superimpose the extracted real part signals to form a mixed signal; S40, forward the mixed signal to the first user and the second user; S50: Based on the known real part of its own transmitted signal and channel information, the system demodulates the real part of the signal transmitted by the peer user from the received mixed signal, thereby realizing information transmission.

[0007] The satellite two-way secure communication method based on signal constellation splitting and superposition provided in this application has the following effects: By placing privacy information and artificial noise in the real and imaginary parts of the signal respectively, and performing preprocessing at the transmitting end so that the real parts of the two user signals have the same coefficient at the untrusted relay, constellation aliasing occurs in the signal received by the relay, making it impossible to decode the privacy information of the two users simultaneously; at the same time, since the artificial noise is placed in the imaginary part and is independent of the real part of the signal, the artificial noise in the signal received by the eavesdropper cannot be eliminated, thereby effectively interfering with the eavesdropper's decoding ability; this method only requires a single time slot to simultaneously complete the artificial noise embedding and constellation superposition operations, which can significantly improve transmission efficiency while ensuring communication security.

[0008] As a further preferred embodiment, in step S10, both the first artificial noise and the second artificial noise are additive Gaussian noise.

[0009] As a further preferred embodiment, in step S10, the real parts of the first and second transmitted signals are generated using the same modulation scheme.

[0010] As a further preferred embodiment, in step S10, the first artificial noise is independent of the real part of the first transmitted signal, and the second artificial noise is independent of the real part of the second transmitted signal.

[0011] Secondly, this application provides a satellite two-way secure communication system for implementing any one of the methods described above, comprising: The signal generation module is used to generate a first transmission signal and a second transmission signal. The real part of the first transmission signal carries the privacy information of a first user, and the imaginary part carries the first artificial noise. The real part of the second transmission signal carries the privacy information of a second user, and the imaginary part carries the second artificial noise. The preprocessing module is used to preprocess the first transmitted signal and the second transmitted signal to compensate for their channel response when they are transmitted to the relay node via the first channel and the second channel, respectively, so that the real part of the first transmitted signal and the real part of the second transmitted signal have the same coefficient at the relay node. The signal processing module is used to receive the preprocessed first and second transmitted signals, extract the real parts of the two signals and discard their imaginary parts, and superimpose the two extracted real part signals to form a mixed signal. The signal forwarding module is used to forward the mixed signal to the first user and the second user; The signal demodulation module is used to demodulate the real part of the signal sent by the peer user from the received mixed signal based on the known real part of its own transmitted signal and channel information.

[0012] As a further preferred embodiment, the signal generation module, the preprocessing module, and the signal demodulation module are respectively located in the first user equipment and the second user equipment.

[0013] As a further preferred embodiment, the signal processing module and the signal forwarding module are located in the relay node.

[0014] As a further preferred option, the relay node is a low Earth orbit satellite or a geostationary orbit satellite.

[0015] It is understandable that the beneficial effects of the second aspect mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here. Attached Figure Description

[0016] Figure 1 This is a flowchart of the satellite two-way secure communication method based on signal constellation splitting and superposition provided in this application; Figure 2 This is a system model of the solution provided in the embodiments of this application, which shows the satellite communication system architecture including user A, user B, satellite relay node and external eavesdropper. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0018] like Figure 1As shown, this application provides a satellite two-way secure communication method based on signal constellation splitting and superposition, including steps S10 to S50, which are detailed below: Step S10: Generate a first transmission signal and a second transmission signal. The real part of the first transmission signal carries the privacy information of the first user, and the imaginary part carries first artificial noise. The real part of the second transmission signal carries the privacy information of the second user, and the imaginary part carries second artificial noise.

[0019] In step S10, both the first artificial noise and the second artificial noise can be additive Gaussian noise to effectively interfere with the eavesdropper's received signal. Furthermore, the first artificial noise is independent of the real part of the first transmitted signal, and the second artificial noise is independent of the real part of the second transmitted signal, thereby avoiding interference with the legitimate user's useful signal.

[0020] Specifically, the real parts of the first and second transmitted signals can be generated using the same modulation method to ensure that the signal format is consistent and facilitates subsequent processing.

[0021] Step S20: Preprocess the first transmitted signal and the second transmitted signal to compensate for their channel response when they are transmitted to the relay node via the first channel and the second channel, respectively, so that the real part of the first transmitted signal and the real part of the second transmitted signal have the same coefficient at the relay node.

[0022] In step S20, channel response compensation is achieved by preprocessing the signal so that the real parts of the two user signals have the same coefficients when they arrive at the relay. This is a key operation for realizing constellation aliasing.

[0023] Step S30: Receive the preprocessed first and second transmission signals, extract the real parts of the two signals and discard their imaginary parts, and superimpose the extracted real part signals to form a mixed signal.

[0024] In step S30, the relay node can eliminate the influence of artificial noise by discarding the imaginary part of the signal. At the same time, since the coefficients of the two real part signals are the same, the constellation points are aliased, making it impossible for the untrusted relay to decode the privacy information of two users at the same time.

[0025] Step S40: Forward the mixed signal to the first user and the second user.

[0026] Step S50: Based on the known real part of the signal transmitted by itself and the channel information, demodulate the real part of the signal transmitted by the peer user from the received mixed signal to realize information transmission.

[0027] The satellite two-way secure communication method based on signal constellation splitting and superposition provided in this application has the following effects: By placing privacy information and artificial noise in the real and imaginary parts of the signal respectively, and performing preprocessing at the transmitting end so that the real parts of the two user signals have the same coefficient at the untrusted relay, constellation aliasing occurs in the signal received by the relay, making it impossible to decode the privacy information of the two users simultaneously; at the same time, since the artificial noise is placed in the imaginary part and is independent of the real part of the signal, the artificial noise in the signal received by the eavesdropper cannot be eliminated, thereby effectively interfering with the eavesdropper's decoding ability; this method only requires a single time slot to simultaneously complete the artificial noise embedding and constellation superposition operations, which can significantly improve transmission efficiency while ensuring communication security.

[0028] In one embodiment, the technical solution to achieve the above objective can be as follows: This embodiment provides a satellite two-way secure communication method based on signal constellation splitting and superposition. The specific implementation process of the proposed solution is as follows: 1. System Model 1.1 System Parameters and Assumptions Consider a satellite communication system such as Figure 2 As shown, the system contains two users, A and B (denoted as A and B respectively). The system consists of an untrusted relay / satellite (denoted as R) and an external eavesdropper (denoted as Eve). Since there is no direct link between user A and user B, information transmission relies on a relay / satellite for forwarding. In this system, all nodes use a single antenna for transmission and reception, and the channels between nodes are independent. Assuming that the relay / satellite R is untrusted by users A and B, the information transmitted by users A and B to the relay is at risk of leakage, and an external eavesdropper exists within the system. , Eavesdropping is also a potential threat. In this system, assume that users A and B can only obtain channel state information between themselves and the relay, while eavesdroppers... This allows us to obtain global channel state information. At any given time, users A and B use the same modulation scheme.

[0029] The original signal constellations transmitted by users A and B (k=A,B) and its corresponding power are denoted as (k=A,B). Simultaneously, the receiver and relay... and eavesdroppers Noise exists at this location, denoted as ( And additive Gaussian noise satisfies ( ). Assume user The channel coefficient to R is ; Relay R to user The channel coefficient is denoted as ; will users The channel coefficient to Eve is denoted as ;Transfer Eve to user The channel coefficient is denoted as At this point, the signals received by the relay / satellite R and the eavesdropper Eve can be represented as follows:

[0030] .

[0031] 1.2 System Security Risk Analysis In cases where relays / satellites are untrusted, this satellite system faces two security vulnerabilities: one from the relay and the other from external eavesdroppers.

[0032] First, we analyze the security threats originating from relays. Typically, different users use different channels to reach the relay, i.e. At this point, if no processing is done on the transmitted signal, the signal received by the relay / satellite R will be the same as... A one-to-one mapping exists, meaning there is a clear and unique correspondence between the constellation at the transmitting end and the constellation received at the receiving end. This relationship ensures accurate information transmission and that the receiving end can flawlessly recover the original information. This one-to-one mapping allows the relay to simultaneously decode signals from users. and For systems that do not intend to relay information, such information poses a security risk. Therefore, existing research has demonstrated that when information... and When the preceding coefficients are the same, the received signal will change. and The constellations are mixed, and the signal received by relay R at this moment can be represented as , It is a constant. That is to say, once and The coefficients are the same, relay The received signal and The loss of the one-to-one mapping relationship makes it difficult for relays to decode user information simultaneously. Therefore, a solution needs to be designed to meet the requirements. and Only when the coefficients are the same can safety be guaranteed.

[0033] Next, we analyze the security threat posed by external eavesdroppers. Because the eavesdropping channel coefficients cannot be known to legitimate users and therefore cannot be canceled out, the signals eavesdropped by external eavesdroppers... and A one-to-one mapping relationship is maintained between them, allowing eavesdroppers to simultaneously decode signals from users under favorable channel conditions. and This information threatens users' privacy. Therefore, unlike internal eavesdropping, it is necessary to find technologies beyond constellation superposition to combat external eavesdropping.

[0034] To address the internal and external eavesdropping issues described above, this application proposes a constellation-splitting-based security mechanism, the specific implementation of which will be detailed later.

[0035] 2. Design of a constellation cascading scheme based on constellation splitting This embodiment details a constellation aliasing scheme based on constellation splitting. The key to constellation splitting lies in separating the private information of the signal from artificial noise. The key to constellation aliasing lies in enabling satellite relay... Constellation aliasing occurs to prevent the simultaneous decoding of user A's and user B's private information. The key to artificial noise is to interfere with eavesdroppers, not legitimate receivers.

[0036] The proposed solution is divided into two phases. Phase 1: and Relaying to satellites The transmission of their private information is subject to eavesdropping. eavesdropping, relay and After receiving information through their respective channels, each attempted to decode the user's private information; Second stage: Relay Forward the received signal back to the user and This process was also affected The user receives the transmitted signal and decodes it, thus completing the communication task.

[0037] It is worth noting that existing solutions require two time slots to complete the embedding of artificial noise and the superposition of constellations during the information uplink transmission phase, but the solution proposed in this patent only requires one time slot.

[0038] 1) Information uplink transmission stage To achieve constellation splitting, we will record the information of user A and user B as follows: , ; , , , They represent signals respectively. and The real and imaginary parts are used, with the real part used to transmit privacy information and the imaginary part embedding artificial noise. and satisfy In addition, User A, User B, and the relay Additive Gaussian noise during transmission can also be written in the form of real and imaginary parts, denoted as: , , ; , , Indicates the real part, , , Indicates noise , and The imaginary part. Combined with channel inversion, user A and user B simultaneously transmit... and ,Right now , .

[0039] relay and The signals received from the user are represented as follows:

[0040]

[0041] After receiving a signal, the relay will discard the imaginary part of the signal, resulting in the following signal:

[0042] The formula reveals that the signal received by the relay is not affected by artificial noise, but user privacy information will experience aliasing. This is because the relay... It is untrustworthy; it will attempt to decode a signal carrying private information. and Information, but due to relay In the received signal The same coefficients before make the relay and The one-to-one mapping relationship is lost. This causes the relay to... Decoding was severely hampered, ultimately making it difficult to decode both signals simultaneously, thus hindering the user's ability to relay signals. The security of private information. Due to interference signals. and The existence of these makes eavesdroppers It is difficult to decode two signals simultaneously, thus ensuring the external security of user privacy information.

[0043] 2) Downlink Information Transmission Phase During the uplink phase, satellite relay Upon receiving a user signal containing interference, the signal will be processed to remove the interference. and At this point, both the signal sent by relay R to the user and the signal heard by the eavesdropper contain only real parts. Therefore, the signal sent by the relay is... .

[0044] During the downward phase and as well as from The received signals are represented as follows:

[0045]

[0046]

[0047] in , .

[0048] Knowing their own real part signal and channel coefficients, users can extract the real part of the other party's signal by dividing their own transmitted signal by these coefficients. This system achieves information transmission. The signals of user A and user B can be transformed into:

[0049]

[0050] The above represents The formula for eavesdropping signals reveals that the coefficients before signals carrying private information are the same, indicating that the eavesdropper... eavesdropped signals and The one-to-one mapping relationship is lost, making it difficult to decode the two signals simultaneously, thus ensuring the external security of user information.

[0051] Key point 1: By using constellation splitting, artificial noise embedding and constellation superposition can be achieved in just one time slot. To achieve constellation splitting, we denote the information of user A and user B as follows: , ; , , , They represent signals respectively. and The real and imaginary parts of the variable are used, with the real part used to transmit private information and the imaginary part used to include artificial noise. and satisfy In addition, User A, User B, and the relay Additive Gaussian noise during transmission can also be written in the form of real and imaginary parts, denoted as: , , ; , , Indicates the real part, , , Indicates noise , and The imaginary part. Combined with channel inversion, user A and user B simultaneously transmit... and ,Right now , .

[0052] relay and The signals received from the user are represented as follows:

[0053]

[0054] After receiving a signal, the relay will discard the imaginary part of the signal, resulting in the following signal:

[0055] The formula reveals that the signal received by the relay is not affected by artificial noise, but user privacy information will experience aliasing. This is because the relay... It is untrustworthy; it will attempt to decode a signal carrying private information. and Information, but due to relay In the received signal The same coefficients before make the relay and The one-to-one mapping relationship is lost. This causes the relay to... Decoding was severely hampered, ultimately making it difficult to decode both signals simultaneously, thus hindering the user's ability to relay signals. The security of private information. Due to interference signals. and The existence of these makes eavesdroppers It is difficult to decode two signals simultaneously, thus ensuring the external security of user privacy information.

[0056] Key point 2: The relay only forwards the real part information and discards the imaginary part information, instead of forwarding both real and imaginary part information simultaneously as in existing solutions.

[0057] The second phase, and as well as from The received signals are represented as follows:

[0058]

[0059]

[0060] in , .

[0061] Knowing their own real part signal and channel coefficients, users can extract the real part of the other party's signal by dividing their own transmitted signal by these coefficients. This system achieves information transmission. The signals of user A and user B can be transformed into:

[0062] . The above represents The formula for eavesdropping signals reveals that the coefficients before signals carrying private information are the same, indicating that the eavesdropper... eavesdropped signals and The one-to-one mapping relationship is lost, making it difficult to decode the two signals simultaneously, thus ensuring the external security of user information.

[0063] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for satellite two-way secure communication based on signal constellation splitting and superposition, characterized in that, The method comprises the following steps: S10, generating a first sending signal and a second sending signal, a real part of the first sending signal carrying privacy information of a first user and an imaginary part carrying first artificial noise, and a real part of the second sending signal carrying privacy information of a second user and an imaginary part carrying second artificial noise; S20, pre-processing the first sending signal and the second sending signal to compensate for channel responses when the first sending signal and the second sending signal are transmitted to a relay node via a first channel and a second channel respectively, so that the real part of the first sending signal and the real part of the second sending signal have the same coefficient at the relay node; S30, receiving the pre-processed first sending signal and the pre-processed second sending signal, extracting the real parts of the two signals and discarding the imaginary parts, and superimposing the extracted real parts to form a mixed signal; S40, forwarding the mixed signal to the first user and the second user; S50, demodulating the real part of the signal sent by the opposite user from the received mixed signal according to the known real part of the signal sent by itself and channel information, and realizing information transmission.

2. The satellite bidirectional secure communication method based on signal constellation splitting and superposition of claim 1, wherein, In step S10, the first artificial noise and the second artificial noise are both additive Gaussian noise.

3. The satellite bidirectional secure communication method based on signal constellation splitting and superposition of claim 1, wherein, In step S10, the real parts of the first sending signal and the second sending signal are generated by using the same modulation mode.

4. The satellite two-way secure communication method based on signal constellation splitting and superposition of claim 1, wherein, In step S10, the first artificial noise is independent of the real part of the first sending signal, and the second artificial noise is independent of the real part of the second sending signal.

5. A satellite two-way secure communication system for implementing the method of any one of claims 1 to 4, characterized in that, The method comprises: a signal generation module configured to generate a first sending signal and a second sending signal, a real part of the first sending signal carrying privacy information of a first user and an imaginary part carrying first artificial noise, and a real part of the second sending signal carrying privacy information of a second user and an imaginary part carrying second artificial noise; a pre-processing module configured to pre-process the first sending signal and the second sending signal to compensate for channel responses when the first sending signal and the second sending signal are transmitted to a relay node via a first channel and a second channel respectively, so that the real part of the first sending signal and the real part of the second sending signal have the same coefficient at the relay node; a signal processing module configured to receive the pre-processed first sending signal and the pre-processed second sending signal, extract the real parts of the two signals and discard the imaginary parts, and superimpose the extracted real parts to form a mixed signal; a signal forwarding module configured to forward the mixed signal to the first user and the second user; and a signal demodulation module configured to demodulate the real part of the signal sent by the opposite user from the received mixed signal according to the known real part of the signal sent by itself and channel information. The signal generation module, the pre-processing module and the signal demodulation module are respectively arranged in the first user equipment and the second user equipment.

6. The satellite two-way secure communication system of claim 5, wherein, The signal processing module and the signal forwarding module are arranged in the relay node.

7. The satellite two-way secure communication system of claim 5, wherein, The relay node is a low earth orbit satellite or a geostationary orbit satellite.

8. The satellite two-way secure communication system of claim 5, wherein, ​

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