Radar low-interception communication method, radar communication system, jammer and storage medium

Abstract

The invention provides a radar low-interception communication method, a radar communication system, a jammer and a storage medium, and relates to the technical field of communication. The method comprises the following steps: acquiring non-ideal channel state information under a current communication link, and constructing an artificial noise signal according to the non-ideal channel state information; according to the transmitting power of the jammer in the plurality of communication states, determining the transmitting power of the neutral transmitting end in the plurality of communication states; according to the non-ideal channel state information, the artificial noise signal and the transmitting power of the neutral transmitting end in a plurality of communication states, hidden communication constraint conditions are constructed, and the hidden communication constraint conditions comprise hidden constraint and channel information error constraint; the constraint condition is optimized and solved, covert communication parameters are obtained, the covert communication parameters comprise the target transmitting power of the main transmitting end and the target power distribution factor of the jammer, the covert transmission rate is maximized under the condition that the covert constraint condition is met, and robust covert communication under the non-ideal channel condition is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of communication, in particular to a radar low-interception communication method, a radar communication system, a jammer and a storage medium. BACKGROUND

[0002] With the rapid development of modern radar systems towards networking and distribution, multi-static radars and networked radars have been widely used in many fields due to their excellent anti-jamming, anti-stealth and high-precision detection capabilities. In a radar system, radar nodes (such as detection radars) need to transmit target point tracks, track information and receive command and control instructions in real time through a backhaul data link. However, such communication links often work in a strong electromagnetic countermeasure environment, facing serious security challenges.

[0003] At present, the traditional radar low-interception probability technology mainly relies on physical layer means such as spread spectrum, frequency hopping and burst communication, and its core goal is to reduce the power spectral density of the signal, making it difficult to be detected and identified.

[0004] However, with the continuous progress of electronic reconnaissance technology, the ability of modern monitoring parties has been upgraded from "whether the signal content can be demodulated" to "whether the communication behavior exists", and the existing radar low-interception probability technology is not enough to cope with the threat of precise active detection and passive monitoring. SUMMARY

[0005] The purpose of the present application is to provide a radar low-interception communication method, a radar communication system, a jammer and a storage medium to solve the technical problems existing in the prior art in view of the deficiencies in the prior art.

[0006] To achieve the above purpose, the technical solutions adopted by the embodiments of the present application are as follows: In a first aspect, the embodiments of the present application provide a radar low-interception communication method applied to a jammer in a radar communication system, the radar communication system further comprising a main sending end, a main receiving end, a monitoring party, a neutral sending end and a neutral receiving end, and the method comprising: obtaining non-ideal channel state information under a current communication link, and constructing an artificial noise signal according to the non-ideal channel state information, the current communication link at least including a first channel from the jammer to the neutral receiving end, a second channel from the jammer to the main receiving end, and a third channel from the jammer to the monitoring party; determining the transmission power of the neutral sending end in multiple communication states according to the transmission power of the jammer in multiple communication states; constructing a covert communication constraint condition according to the non-ideal channel state information, the artificial noise signal and the transmission power of the neutral transmitter in multiple communication states, the covert communication constraint condition comprising: a covert constraint, a channel information error constraint and a power constraint, the power constraint being used to represent that the sum of the target transmission power of the main transmitter and the target transmission power of the jammer is less than a preset maximum transmission power threshold; optimizing and solving the constraint condition to obtain a covert communication parameter, the covert communication parameter comprising: the target transmission power of the main transmitter, the target power allocation factor of the jammer and the target transmission power of the jammer, wherein the signal power received by the monitoring party under the action of the covert communication parameter does not change greatly.

[0007] Optionally, the artificial noise signal is constructed according to the non-ideal channel state information, comprising: in the second channel null space, based on the first channel state information of the jammer to the neutral receiver and the second channel state information of the jammer to the main receiver in the non-ideal channel state information, a maximum ratio combining method is used to determine a first beam vector, so that the power of the artificial noise signal at the neutral receiver is maximized; the artificial noise signal is distributed in both the second channel and the first channel null space, and is denoted as a second beam vector; the artificial noise signal is obtained according to the first beam vector and the second beam vector.

[0008] Optionally, the artificial noise signal is obtained according to the first beam vector and the second beam vector, comprising: based on the power allocation factor to be determined, the first beam vector and the second beam vector are weighted and summed to generate the artificial noise signal.

[0009] Optionally, the transmission power of the neutral transmitter in multiple communication states is determined according to the transmission power of the jammer in multiple communication states, comprising: a preset signal-to-noise ratio threshold, channel state information between the neutral transmitter and the neutral receiver, the power allocation factor, the transmission power of the jammer in the current communication state, the channel state information of the first channel and the first beam vector are input into a preset transmission power formula to obtain the transmission power of the neutral transmitter in the current communication state.

[0010] Optionally, the transmission power formula is: ; wherein, is a signal-to-noise ratio threshold, channel state information between the neutral transmitter and the neutral receiver, a power allocation factor, transmit power of the jammer in multiple communication states, channel state information of the first channel, the first beam vector, zero mean variance of the neutral receiver.

[0011] Optionally, the constructing a covert communication constraint condition according to the non-ideal channel state information, the artificial noise signal and the transmit power of the neutral transmitter in multiple communication states comprises: inputting the non-ideal channel state information, the artificial noise signal and the transmit power of the neutral transmitter in multiple communication states into a pre-constructed covert constraint formula to construct the covert constraint; inputting the non-ideal channel state information into a pre-constructed non-ideal channel error constraint formula to construct the non-ideal channel information error constraint.

[0012] Optionally, the optimizing and solving the constraint condition to obtain a covert communication parameter comprises: converting the constraint condition into a linear matrix inequality using an S-process; performing one-dimensional traversal search on the power allocation factor in the linear matrix inequality to obtain a target power allocation factor of the jammer; substituting the target power allocation factor of the jammer into the linear matrix inequality and optimizing and solving the linear matrix inequality to obtain a target transmit power of the main transmitter and a target transmit power of the jammer.

[0013] In a second aspect, the embodiments of the present application further provide a radar communication system, comprising: a main transmitter, a main receiver, a monitoring party, a jammer, a neutral transmitter and a neutral receiver; The jammer is configured to execute the radar low-interception communication method.

[0014] In a third aspect, the embodiments of the present application provide a computer readable storage medium having a computer program stored thereon, and the computer program is executed by a processor to implement the radar low-interception communication method.

[0015] The present application has the following beneficial effects: The application provides a radar low-interception communication method, a radar communication system, a jammer and a storage medium.

[0016] In order to make the above-mentioned purposes, features and advantages of the application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the application, and therefore should not be regarded as a limitation to the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0018] Figure 1 An architecture schematic diagram of a radar communication system provided by the embodiments of the application is provided. Figure 2 A flowchart of a radar low-interception communication method provided by the embodiments of the application is provided. Figure 3 A flowchart of another radar low-interception communication method provided by the embodiments of the application is provided. Figure 4 A flowchart of another radar low-interception communication method provided by the embodiments of the application is provided. Figure 5 A flowchart of another radar low-interception communication method provided by the embodiments of the application is provided. Figure 6 A radar low-interception communication method provided by the embodiments of the application is compared with other methods in terms of effects. Figure 7 A structure schematic diagram of a jammer provided by the embodiments of the application is provided. DETAILED DESCRIPTION

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. The components of the embodiments of the present application generally described and shown in the drawings herein can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0021] First, the background art related to the present application is introduced.

[0022] With the continuous progress of electronic reconnaissance technology, the ability of modern monitoring parties has been upgraded from “whether the signal content can be demodulated” to “whether the communication behavior exists”. The existing radar low probability of interception technology is not enough to cope with the threat of precise active detection and passive listening.

[0023] Therefore, the concept of concealment of wireless communication is introduced in the field of radar, aiming to realize low interception / low detection probability (LPI / LPD) backhaul that is not only “unintelligible” but also “invisible”. The core of covert communication lies in hiding signals by utilizing the inherent uncertainty of the system (such as link error, multipath effect, clock drift, etc.), or enhancing the cover by artificially injecting interference and noise.

[0024] Existing research (such as He, Biao, Ta, Hien Q, Zou, Li, etc.) has deeply analyzed the influence of noise and channel uncertainty on the concealment rate and detection performance, and proposed the strategy of artificial noise (Artificial Noise, AN) generated by the source, relay or special interference node. Combined with multi-antenna technology, scholars (such as Forouzesh, Moslem, Ma, Shuai, etc.) further developed methods such as maximum ratio transmission (MRT), zero-forcing beamforming and antenna grouping to optimize the interference performance.

[0025] Although the above-mentioned technology has a breakthrough in theory, its actual effect is seriously dependent on perfect channel state information (CSI). In actual radar backhaul, calibration errors, high-speed platform motion and malicious interference often cause CSI mismatch, which in turn causes main lobe leakage and null misalignment, greatly weakening the concealment. In addition, existing researches focus on enemy and ally confrontation, ignoring the widely existing neutral nodes (such as civilian radars, base stations, etc.) in the battlefield. These devices are both environmental background and potential cover resources, but there is currently a lack of systematic theory to incorporate them into the design of covert communication.

[0026] Therefore, how to realize efficient covert communication in the coexistence environment of neutral devices under the realistic constraint of being difficult to obtain accurate CSI has become a key problem to be solved at present.

[0027] In view of the above question, the application provides a radar low-interception transmission method assisted by neutral nodes based on non-ideal link information. In a complex environment where a monitoring party (Willie) and multiple neutral nodes are known, an interference machine Jammer actively constructs controllable artificial noise signals, and through joint optimization of the transmission power of a main sending end Alice and the power allocation factor of the interference machine, the communication quality of a legal receiving end Bob is satisfied while the illegal monitoring party (Willie) cannot effectively detect the communication behavior, so as to realize wireless transmission with high reliability and strong concealment, and realize robust covert communication under non-ideal channel conditions.

[0028] Some embodiments of the application will be described in detail below with reference to the accompanying drawings. In the case of no conflict, the embodiments described below and the features in the embodiments can be combined with each other.

[0029] Firstly, the architecture of the radar communication system involved in the application is introduced.

[0030] Optionally, as shown in FIG. 1, a schematic diagram of the architecture of a radar communication system provided by an embodiment of the application is shown, as shown in FIG. 2, the radar communication system comprises a main sending end Alice, a main receiving end Bob, a monitoring party Willie, an interference machine Jammer, a neutral sending end Transmitter and a neutral receiving end Receiver. Figure 1 Figure 1 As shown in FIG. 2, the radar communication system shown in the application comprises a main sending end Alice, a main receiving end Bob, a monitoring party Willie, an interference machine Jammer, a neutral sending end Transmitter and a neutral receiving end Receiver.

[0031] As shown in FIG. 2, the radar communication system shown in the application comprises a main sending end Alice, a main receiving end Bob, a monitoring party Willie, an interference machine Jammer, a neutral sending end Transmitter and a neutral receiving end Receiver. Figure 1 As shown in FIG. 2, the radar communication system shown in the application comprises a main sending end Alice, a main receiving end Bob, a monitoring party Willie, an interference machine Jammer, a neutral sending end Transmitter and a neutral receiving end Receiver.

[0032] ​Wherein, the main sending end Alice needs to send confidential information to the main receiving end Bob, and the jammer Jammer protects the communication process between the main sending end Alice and the main receiving end Bob from being discovered by the monitoring party Willie by sending artificial noise (AN).

[0033] Secondly, the neutral sending end Transmitter sends signals to the neutral receiving end Receiver, determines the transmission power of the neutral sending end Transmitter in the corresponding communication state based on the transmission power of the jammer in multiple communication states , and meets the communication quality demand of the neutral sending end Transmitter.

[0034] Wherein, the Jammer is equipped with L antennas, and other nodes are single antennas.

[0035] It should be noted that the channel from the main sending end Alice to the neutral receiving end Receiver and the channel from the main sending end Transmitter to the main receiving end Receiver do not exist.

[0036] The specific implementation process of the radar low-interception communication method provided by the application will be explained and described through the following embodiments.

[0037] Optionally, as shown in Figure 2 , it is a flowchart of a radar low-interception communication method provided by the embodiment of the application, as shown in Figure 2 , the method comprises: S101, acquiring non-ideal channel state information under the current communication link, and constructing an artificial noise signal according to the non-ideal channel state information.

[0038] Wherein, the current communication link at least includes: a first channel from the jammer to the neutral receiving end , a second channel from the jammer to the main receiving end , and a third channel

[0039] from the jammer to the monitoring party. Optionally, all channels are flat Rayleigh fading, and the non-ideal channel state information under the current communication link obeys a complex Gaussian distribution with zero mean and variance . Wherein, the first channel , the second channel and the third channel respectively represent the channel information from the jammer Jammer to the main receiving end Bob, the neutral receiving end Receiver and the monitoring party Willie.​

[0040] In the embodiment, the artificial noise signal is constructed by the double zero-forcing method and in combination with non-ideal channel state information . Therefore, the artificial noise signal can be projected to a spatial direction which has the least influence on the main receiving end Bob and the greatest interference on the monitoring party Willie.

[0041] S102, determine the transmission power of the neutral transmitter in multiple communication states according to the transmission power of the jammer in the multiple communication states.

[0042] wherein the communication state refers to the main transmitter Alice being in a silence state 1 or a transmission state 0.

[0043] In the embodiment, since the neutral transmitter Transmitter needs to ensure the communication quality of the neutral receiving end Receiver, the signal-to-noise ratio (SNR) is used as a measurement index, and therefore needs to be met. The Transmitter uses the minimum power that meets the requirement as the transmission power.

[0044] wherein the monitoring party Willie judges whether the main transmitter Alice is transmitting through the signal received by itself. The main transmitter Alice being in a silence state is recorded as an event , and the main transmitter Alice being in a transmission state is recorded as an event . In the two communication states, the corresponding transmission power of the jammer Jammer is and , and the corresponding transmission power of the neutral transmitter Transmitter is and . Therefore, in the embodiment, the transmission power of the neutral transmitter in the corresponding communication state can be determined based on the transmission power of the jammer in the multiple communication states .

[0045] Optionally, the application proposes a neutral node assisted covert communication scheme based on non-ideal channel information. In the presence of an illegal monitoring party, with the help of a jammer, indirect interference is generated to the illegal monitoring party based on non-ideal channel information and by means of the interference generated by other neutral nodes in the environment to protect the communication of the own party. The neutral node only considers the reliability of its own transmission link, and has no subjective intention to help any party.

[0046] S103, construct a covert communication constraint condition according to the non-ideal channel state information, the artificial noise signal, and the transmission power of the neutral transmitter in multiple communication states.

[0047] ​​The covert communication constraint conditions include a concealment constraint, a channel information error constraint, and a power constraint. The power constraint is used to represent that a sum of a target transmission power of the primary transmitter and a target transmission power of the jammer is less than a preset maximum transmission power threshold, i.e. wherein, is the target transmission power of the primary transmitter Alice, is the target transmission power of the jammer Jammer when the primary transmitter is in a transmission state, is the maximum transmission power threshold. It should be noted that, is the transmission power of the jammer Jammer when the primary transmitter Alice is in a silence state. It is assumed that when Alice is silent, the jammer Jammer generates an interference signal at a constant maximum power to confuse Willie, i.e. wherein is the total power budget of the legal node.

[0048] Optionally, the concealment constraint is a performance boundary condition that the monitoring party Willie cannot determine whether there is a communication behavior with a probability significantly higher than random guessing, and is a basic requirement for realizing "covert communication".

[0049] Generally, in a wireless environment, the monitoring party Willie determines whether there is a communication by analyzing the energy, distribution or characteristics of the received signal. If the primary transmitter Alice directly transmits a signal without any protection mechanism, the monitoring party Willie can easily find the anomaly through an energy detector. Therefore, the transmission power and interference strategy of the primary transmitter Alice can be controlled through the concealment constraint, so that the average received power at the monitoring party Willie changes very little, so that its detection performance degrades to near the blind guessing level. That is, the concealment constraint is used to limit the observable disturbance amplitude caused by the primary transmitter Alice and the auxiliary jammer Jammer at the monitoring party Willie, so as to ensure that the monitoring party Willie cannot reliably detect the communication behavior.

[0050] The channel information error constraint is used to describe the uncertainty of the channel state information in the actual communication link, and to ensure that the performance of the radar communication system still meets the design requirements of concealment and reliability when the channel estimation error is within a preset range.

[0051] In an actual communication system, due to mobility, feedback delay, quantization error, etc., the obtained channel information always has a certain deviation. Therefore, the channel information error constraint can be used to solve the problem of inaccurate channel information in the actual system, and to improve the practicability and stability of the system.

[0052] In the embodiment, considering the concealment requirement and channel uncertainty, two groups of core constraints, i.e., concealment constraints and channel information error constraints, are constructed by using non-ideal channel state information, artificial noise signals and transmission power of the neutral sender under multiple communication states.

[0053] S104, the constraint conditions are optimized and solved to obtain the concealment communication parameters.

[0054] The concealment communication parameters include: target transmission power of the main sender and target power allocation factor of the jammer , wherein the signal power received by the monitoring party does not change greatly under the action of the concealment communication parameters.

[0055] Optionally, the constraint conditions can be converted into a convex optimization sub-problem, and a CVX, SeDuMi, MOSEK or the like tool package is used for optimization solving to obtain optimal concealment communication parameters, so that the concealment transmission rate of the main link (Alice Bob) is maximized without relying on perfect channel information, and robust concealment communication under non-ideal channel conditions is realized.

[0056] In summary, the radar low-interception communication method provided in the embodiments of the application realizes the following effects: in a complex environment where a monitoring party and multiple neutral nodes exist, the jammer generates artificial noise based on non-ideal channel state information under the current communication link; and based on non-ideal channel state information, artificial noise signals and transmission power of the neutral sender under multiple communication states, concealment communication constraint conditions are constructed, i.e., the communication process is hidden by the interference generated by other neutral nodes in the environment, so that the communication behavior is truly hidden in the environment; and the concealment communication constraint conditions are optimized and solved to obtain optimal concealment communication parameters, the concealment transmission rate is maximized under the concealment constraint conditions, and robust concealment communication under non-ideal channel conditions is realized, thereby improving the concealment communication performance compared with the traditional method under the non-ideal channel information condition.

[0057] Optionally, as shown in Figure 3 , the artificial noise signal is constructed according to the non-ideal channel state information in the step S101, including: S201, in the second channel null space, the first channel state information from the jammer to the neutral receiving end and the second channel state information from the jammer to the main receiving end in the non-ideal channel state information are used to determine the first beam vector by using the maximum ratio combining method, so that the power of the artificial noise signal at the neutral receiving end is maximized.

[0058] S202, the artificial noise signal is distributed in the second channel and the first channel null space, and is recorded as the second beam vector.

[0059] S203, obtaining an artificial noise signal according to the first beam vector and the second beam vector.

[0060] In this embodiment, in the second channel null space, the jammer Jammer maximizes the artificial noise power at the receiver Receiver by using maximum ratio combining (MRT) based on the first channel state information from the jammer to the neutral receiver in the non-ideal channel state information , the second channel state information from the jammer to the main receiver , to obtain the first beam vector , which is shown in the following formula (1): (1) wherein, is an identity matrix.

[0061] Then, the artificial noise signal is uniformly distributed in the null space, and the second beam vector ; and based on the first beam vector and the second beam vector , the artificial noise signal is obtained.

[0062] Optionally, the step S203 comprises: Based on the power allocation factor to be determined, the first beam vector and the second beam vector are weighted and summed to generate the artificial noise signal.

[0063] In this embodiment, the first beam vector and the second beam vector are weighted and summed to generate the artificial noise signal , which is shown in the following formula (2): (2) wherein, is the power allocation factor to be determined, and represent the artificial noise signals sent to the neutral receiver Receiver and the monitoring party Willie respectively.

[0064] Optionally, the present application adopts a double zero-forcing beamforming scheme to construct the artificial noise signal, which includes two parts, one part is located in the null space of the main receiver Bob, and the other part is distributed in the channel null space of the jammer Jammer-Bob and Jammer-Receiver (neutral receiver), and the proportion of the two parts can be adjusted by the power allocation factor.

[0065] Optionally, the step S102 comprises: ​The preset signal-to-noise ratio threshold, the channel state information between the neutral transmitter and the neutral receiver, the power allocation factor, the transmission power of the jammer in the current communication state, the channel state information of the first channel, and the first beam vector are input into a preset transmission power formula to obtain the transmission power of the neutral transmitter in the current communication state.

[0066] The transmission power formula is established according to the relationship among the minimum signal-to-noise ratio required by the neutral receiver, the channel gain, the artificial noise signal injection intensity, and the first beam vector, and is used to realize adaptive optimization of the transmission power under the premise of guaranteeing the reliability of the neutral link.

[0067] To ensure the basic communication quality of the neutral receiver, such as feedback, monitoring, or cooperative detection, the minimum acceptable signal-to-noise ratio, that is, the signal-to-noise ratio threshold, needs to be set. .

[0068] In an implementable manner, the optimal transmission power of the neutral transmitter in the current communication state is dynamically determined by a pre-modeled transmission power formula using the current channel state, the interference configuration, and the performance target. Specifically, the signal-to-noise ratio threshold , the channel state information between the neutral transmitter and the neutral receiver , the power allocation factor , the transmission power of the jammer in the current communication state , the channel state information of the first channel , and the first beam vector are input into the transmission power formula to obtain the transmission power of the neutral transmitter in the current communication state .

[0069] Optionally, the transmission power formula is shown in the following formula (3): (3) Wherein, the signal-to-noise ratio threshold is the channel state information between the neutral transmitter and the neutral receiver is the power allocation factor is the transmission power of the jammer in the multiple communication states is the channel state information of the first channel is the first beam vector is and the zero-mean variance of the neutral receiver is

[0070] When the main transmitter Alice is in communication mode, the received signals of the main receiver Bob, the neutral receiver Receiver, and the monitoring party Willie are as shown in the following formulas (4)-(6): (4) (5) (6) in, , and These represent the artificial noise signals at the main receiver Bob, the neutral receiver Receiver, and the monitoring point Willie, respectively, and are independent of each other and each obeys a different noise standard. , and Distribution. Among them, and These represent the signals transmitted by the main transmitter Alice and the neutral transmitter Transmitter, respectively. It is assumed that all signals are circularly symmetric complex Gaussian random variables with zero mean and unit variance, i.e. . , and These represent the transmit power of the main transmitter Alice, the neutral transmitter Transmitter, and the jammer, respectively.

[0071] The signal-to-noise ratios of the main receiver Bob, the neutral receiver Receiver, and the monitoring party Willie are shown in the following formulas (7)-(9): (7) (8) (9) Since the neutral transmitter needs to guarantee the communication quality of the neutral receiver, measured by the signal-to-noise ratio (SNR), it must meet the following requirements. The neutral transmitter takes the minimum power required to meet this requirement as its transmission power, and thus the transmission power formula of the neutral transmitter in the current communication state, as shown in formula (3) above, is constructed.

[0072] It can be seen that by adjusting This can affect the transmission power of the neutral transmitter, thereby indirectly changing the interference received by the monitoring party, Willie.

[0073] Optionally, refer to Figure 4 As shown, step S103 above includes: S301, inputting the non-ideal channel state information, the artificial noise signal and the transmission power of the neutral transmitter in multiple communication states to the pre-constructed concealment constraint formula to construct the concealment constraint.

[0074] Optionally, the monitoring party Willie judges whether the main transmitter Alice transmits through the signal received by itself. When the main transmitter Alice is silent, it is recorded as event , and when the main transmitter Alice transmits, it is recorded as event . The corresponding transmission power of the jammer Jammer in the two states is and respectively. The corresponding transmission power of the neutral transmitter Transmitter in the two states is and respectively. Assuming that the prior probabilities of are both 0.5, the false alarm probability is shown in the following formula (10): (10) wherein, and respectively represent the false alarm probability and the missed detection probability. When is greater than or equal to the threshold , the transmission can be considered as concealed.

[0075] Therefore, based on the non-ideal channel state information, the artificial noise signal and the transmission power of the neutral transmitter in multiple communication states, the constructed concealment constraint is shown in the following formula (11): (11) wherein, ; ; .

[0076] In order to improve the concealment performance of the system, the transmission power of the main transmitter Alice and the power allocation factor of the jammer are jointly optimized to maximize the concealment rate of the main receiver Bob, while satisfying the concealment constraint and the power constraint of the monitoring party Willie. Considering that the transmitter is a public node, which is usually a base station, its power budget can be regarded as infinite compared with the main transmitter Alice and the jammer, so the transmission power constraint of the neutral transmitter is not set here. Assuming that the main transmitter Alice is silent, the jammer generates an interference signal at a constant maximum power to confuse the monitoring party Willie, that is, the transmission power of the neutral transmitter in the silent communication state is , wherein is the total power budget of the legal node.

[0077] Considering the channel estimation error, the actual channel state information is usually non-ideal. Therefore, the expression is used as the concealment constraint. In mathematics, the optimization problem can be expressed as: , , , .

[0078] Therefore, the concealment constraint can be converted into the formula (12) as shown below: (12) wherein is the root of the equation , . In addition, , , and .

[0079] S302, input the non-ideal channel state information into the pre-constructed non-ideal channel error constraint formula, and construct a non-ideal channel information error constraint.

[0080] Optionally, input the non-ideal channel state information into the pre-constructed non-ideal channel error constraint formula, and construct a non-ideal channel information error constraint, which is specifically shown in the following formula (13) - formula (15): (13) (14) (15) wherein is the channel state information from the jammer Jammer to the monitoring party Willie, is the channel state information from the neutral transmitter Transmitter to the monitoring party Willie, is the channel state information from the main transmitter Alice to the monitoring party Willie.

[0081] Optionally, referring to Figure 5 , the above step S104 includes: S401, convert the constraint condition into a linear matrix inequality using an S-process.

[0082] S402, perform one-dimensional traversal search on the power allocation factor in the linear matrix inequality to obtain the target power allocation factor of the jammer.

[0083] S403, the target power allocation factor of the jammer is substituted into the linear matrix inequality, and the linear matrix inequality is optimized and solved to obtain the target transmission power of the main sending end and the target transmission power of the jammer.

[0084] In the embodiment, the optimization problem is difficult to process due to the three non-ideal channel information error constraints constructed above. Therefore, the S-process is adopted to combine the three "non-ideal channel information error constraints" with the "cover constraint", and convert them into linear matrix inequalities, and the cover constraint can be equivalently re-expressed as shown in the following formula (16)-(17): (16) (17) And substitute the non-ideal channel information expression into the above formula to obtain the following formula (18)-(19): (18) (19) Wherein, define: ; ; ; ; The first cover constraint shown in formula (16) can be converted into the following formula (20): (20) Finally, the first cover constraint can be represented as shown in the following formula (21):

[0085] Similarly, define: ; ; .

[0086] The second cover constraint shown in the above formula (17) can be represented as shown in the following formula (22): (22) In addition, the three non-ideal channel information error constraints can be represented as shown in the following formula (23): (23) According to the S-process, the cover constraint and the channel information error constraint can be jointly represented as shown in the following formula (24)-(25): (24) (25) Ultimately, the optimization problem is obtained:

[0087] And the power allocation factor in the linear matrix inequality A one-dimensional traversal search is performed to obtain the jammer's target power allocation factor. This factor is then substituted into a linear matrix inequality, and CVX (a MATLAB toolbox for solving convex optimization problems) is used to optimize and solve the inequality, yielding the target transmit power of the main transmitter. and the target transmission power of the jammer .

[0088] Optionally, refer to Figure 6 The figure shown is a comparison of the effects of using the radar low-intercept communication method provided in this application with other methods. Figure 6 This demonstrates the transmission power of the main transmitter, Alice. Statistical characteristics of the received signal from the main transmitter Alice to the monitoring receiver Willie The relationship curves were compared, and the neutral node-assisted covert communication method based on non-ideal channel information proposed in this application was compared with the method without neutral node assistance and the method using MRT (maximum ratio transmission) only for the monitoring party. It can be seen that, with The increase, First increase, then decrease. This is because when When the size is small, in order to ensure that the concealment requirement is met, in a silent state and transmission status Under these conditions, the signal power received by the monitoring party Willie must not change significantly.

[0089] It is important to note that in silent mode In this state, the jammer's transmit power is Even if the main sender Alice is in the transmission state In this state, signals are transmitted at full power budget, because Even at a relatively small level, the monitoring unit Willie can still detect the decrease in received power.

[0090] Therefore, to ensure covert transmission, more power needs to be allocated to the jammer; that is to say, The smaller the value, the less power is allocated to the main transmitter, Alice, to satisfy the concealment constraint. A larger value means that the primary sender, Alice, is closer to the monitoring party, Willie, making it easier for Willie to detect. Therefore, The greater, It can be observed that the proposed method is better than the other two methods, which verifies the effectiveness of the proposed method.

[0091] In summary, the radar low-interception communication method proposed in the application can obtain optimal parameters of covert communication under the condition of non-ideal channel information in the neutral node coexistence scene and based on non-ideal channel information, and the results show that the method has better covert communication performance than the method without the aid of the neutral node and other beam methods.

[0092] Figure 7 A structure diagram of an interference machine is provided for the embodiments of the application. The interference machine can be a computing device with data processing function, and the interference machine has a signal transmitting function and can transmit artificial noise signals to the main receiving end Bob, the neutral receiving end Receiver and the monitoring party Willie.

[0093] The interference machine includes a processor 701 and a memory 702.

[0094] The memory 702 is used to store programs, and the processor 701 calls the programs stored in the memory 702 to execute the above-mentioned method embodiments. The specific implementation manners and technical effects are similar, and will not be described here.

[0095] Optionally, the application also provides a program product, for example, a computer readable storage medium, including a program, which is used to execute the above-mentioned method embodiments when executed by a processor.

[0096] In the embodiments provided in the application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are only schematic. For example, the flowcharts and block diagrams in the drawings show the possible implementation architectures, functions and operations of the devices, methods and computer program products according to the embodiments of the application. In this regard, each block in the flowcharts or block diagrams can represent a module, a program segment or a part of code, which contains one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur in different orders from those noted in the drawings. For example, two consecutive blocks can actually be executed in parallel, and sometimes they can be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and the combination of blocks in the block diagram and / or flowchart, can be implemented by a dedicated hardware-based system for executing the specified functions or actions, or can be implemented by a combination of dedicated hardware and computer instructions.

[0097] In addition, each functional module in each embodiment of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0098] If the functions are realized in the form of software function modules and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts that make contributions to the prior art or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various program code storage media.

[0099] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0100] It is obvious for those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and the present application can be realized in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present application. Any reference signs in the claims should not be regarded as limiting the claims.

Claims

1. A radar low probability of intercept communication method, characterized by, The jammer is applied to a radar communication system, and the radar communication system further comprises a main sending end, a main receiving end, a monitoring party, a neutral sending end and a neutral receiving end, and the method comprises: obtaining non-ideal channel state information under a current communication link, and constructing an artificial noise signal according to the non-ideal channel state information, wherein the current communication link at least comprises a first channel from the jammer to the neutral receiving end, a second channel from the jammer to the main receiving end and a third channel from the jammer to the monitoring party; determining transmission power of the neutral sending end in multiple communication states according to transmission power of the jammer in the multiple communication states; constructing a covert communication constraint condition according to the non-ideal channel state information, the artificial noise signal and the transmission power of the neutral sending end in the multiple communication states, wherein the covert communication constraint condition comprises a covert constraint, a channel information error constraint and a power constraint, and the power constraint is used for representing that a target transmission power of the main sending end and a target transmission power of the jammer are less than a preset maximum transmission power threshold; optimizing and solving the constraint condition to obtain a covert communication parameter, wherein the covert communication parameter comprises the target transmission power of the main sending end, a target power allocation factor of the jammer and the target transmission power of the jammer, and signal power received by the monitoring party does not change greatly under the action of the covert communication parameter.

2. The method of claim 1, wherein, The method comprises the following steps. In a second channel null space, first beam vectors are determined by using a maximum ratio combining method based on first channel state information of the jammer to the neutral receiving end and second channel state information of the jammer to the main receiving end in the non-ideal channel state information, so that power of the artificial noise signal at the neutral receiving end is maximized; artificial noise signals are distributed in the second channel and the first channel null space, and are recorded as second beam vectors; the artificial noise signal is obtained according to the first beam vectors and the second beam vectors.

3. The method of claim 2, wherein, The method comprises the following steps. The first beam vectors and the second beam vectors are weighted and summed based on a power allocation factor to be determined, and the artificial noise signal is generated.

4. The method of claim 1, wherein, The method comprises the following steps. The preset signal-to-noise ratio threshold, channel state information between the neutral sending end and the neutral receiving end, the power allocation factor, transmission power of the jammer in a current communication state, first channel state information and first beam vectors are input into a preset transmission power formula to obtain transmission power of the neutral sending end in the current communication state.

5. The method of claim 4, wherein, The method comprises the following steps. The transmit power formula is: ; wherein, is a signal-to-noise ratio threshold, is channel state information between the neutral transmitting end and the neutral receiving end, is the power allocation factor, is the jammer transmitting power in multiple communication states, is channel state information of the first channel, is the first beam vector, is the zero-mean variance of the neutral receiving end.

6. The method of claim 1, wherein, The method comprises the following steps. The non-ideal channel state information, the artificial noise signal and the transmission power of the neutral transmitter under multiple communication states are input into a pre-constructed concealment constraint formula to construct the concealment constraint; The non-ideal channel state information is input into a pre-constructed non-ideal channel error constraint formula to construct the non-ideal channel information error constraint.

7. The method of claim 1, wherein, The constraint condition is optimized and solved to obtain a concealment communication parameter, including: The constraint condition is converted into a linear matrix inequality using an S-process; A one-dimensional traversal search is performed on a power distribution factor in the linear matrix inequality to obtain a target power distribution factor of the jammer; The target power distribution factor of the jammer is substituted into the linear matrix inequality, and the linear matrix inequality is optimized and solved to obtain a target transmission power of the main transmitter and a target transmission power of the jammer.

8. A radar communication system, characterized by The radar communication system comprises a main transmitter, a main receiver, a monitoring party, a jammer, a neutral transmitter and a neutral receiver; The jammer is configured to perform the method of any one of claims 1-7.

9. A jammer, characterized by, including: A processor, a storage medium and a bus, the storage medium storing machine readable instructions executable by the processor, when the electronic device is running, the processor and the storage medium communicate through the bus, the processor executes the machine readable instructions to perform the steps of the method of any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which is executed by the processor to perform the method of any one of claims 1-7 when the processor is running.

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