Method and apparatus for covert communication based on intermediate node assistance

Abstract

The application relates to the field of communication security technology and provides a hidden communication method and device based on an intermediate node auxiliary, wherein multiple communication parameters are acquired, the multiple communication parameters at least include communication parameters between a monitoring party and an intermediate transmitting party, a jammer and a transmitting party respectively, a hidden communication constraint function is determined according to the multiple communication parameters, an optimization problem of transmitting information of the transmitting party and the jammer when the transmitting party transmits a signal to a receiving party is constructed according to the hidden communication constraint function, the optimization problem is solved, and the transmitting information of the transmitting party and the jammer is acquired. In this way, when the transmitting party transmits a signal to the receiving party, the monitoring party can monitor whether the transmitting party transmits information to the receiving party, the influence of the intermediate transmitting party on the monitoring party when the intermediate transmitting party transmits a signal is considered, network resources in the hidden communication system are fully utilized, and the hidden communication between the transmitting party and the communication party is efficiently realized.

Description

Technical Field

[0001] The present invention relates to the field of communication security technology, and in particular to a covert communication method and device based on the assistance of an intermediate node. Background Art

[0002] The exponential growth of the number of devices on the internet has increased the need for privacy and anti-eavesdropping security. Traditionally, wireless networks have been able to protect messages from eavesdropping attacks by using encryption and physical layer security when transmitting messages from a transmitter to a receiver. However, in some cases, it is necessary to protect not only the content of the transmitted message but also the communication process itself. In such cases, low-detection or covert communication methods can be used to prevent unauthorized monitoring.

[0003] In existing technology, covert communication is achieved by exploiting the uncertainty of the Willie decoder of an illegal monitoring party. This is to conceal the communication between the transmitter Alice and the receiver Bob. Specifically, a jammer generates and transmits artificial noise. This noise, combined with channel noise, confuses the illegal monitoring party, enabling covert communication between the transmitter Alice and the receiver Bob.

[0004] As covert communication research deepens, its application scope continues to expand, encompassing diverse areas such as relay networks, drone networks, and the Internet of Things. In these networks, the surge in the number of frequency-using devices and the widespread adoption of wireless communication technologies has led to a surge in the number of unrelated nodes, making the electromagnetic environment more complex. However, existing technologies primarily focus on the legitimate participants in the covert transmission process, Alice (transmitter) and Bob (receiver), as well as illicit monitoring parties, while ignoring the potential impact of unrelated nodes (other transmitters and receivers) on communication. This results in underutilized network resources and, consequently, inefficiency in achieving covert communication. Summary of the Invention

[0005] Based on this, it is necessary to provide a covert communication method and device based on the assistance of intermediate nodes to address the above technical problems.

[0006] In a first aspect, an embodiment of the present invention provides a covert communication method based on the assistance of an intermediate node, which is applied to a covert communication system, wherein the covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver. The method includes:

[0007] Acquire multiple communication parameters, wherein the multiple communication parameters at least include: communication parameters between the monitoring party and the intermediate transmitter, the jammer, and the transmitter respectively;

[0008] determining a covert communication constraint function based on a plurality of communication parameters;

[0009] According to the covert communication constraint function, constructing an optimization problem of transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver;

[0010] The optimization problem is solved to obtain transmission information of the transmitter and the jammer.

[0011] In one embodiment, the covert communication constraint function is defined by the following expression:

[0012]

[0013] Among them, P t0 represents the transmission power of the intermediate transmitter when the transmitter is silent, h tw represents the channel parameters between the intermediate transmitter and the monitoring party, α represents the power allocation factor, P j0 represents the transmit power of the jammer when the transmitter is silent, h jw represents the channel parameters between the jammer and the monitoring party, Indicates h jw The corresponding conjugate transpose, w r represents the beam between the jammer and the intermediate receiver, L represents the number of antennas equipped by the jammer, and w w represents the beams of the jammer and the monitoring party, represents the noise variance at the monitoring point, P a represents the transmission power at the transmitter, h aw represents the channel parameter between the transmitter and the monitoring party, P t1 represents the transmission power of the intermediate transmitter when the transmitter sends a signal, h tw represents the channel parameter between the intermediate transmitter and the monitoring party, P j1 Indicates the transmit power of the jammer when the transmitter sends a signal.

[0014] In one embodiment, the method further includes: the beam between the jammer and the intermediate receiver is: a beam when a noise signal is transmitted in a channel null space between the jammer and the intermediate receiver by a double zero-forcing beamforming method;

[0015] The beams of the jammer and the monitoring party are: beams formed when a noise signal is transmitted in a channel null space between the jammer and the monitoring party by a double zero-forcing beamforming method;

[0016] The beams between the jammer and the intermediate receiver are defined by the following expression:

[0017]

[0018] Among them, I N represents the unit matrix of dimension L, h jb represents the channel parameters between the jammer and the receiver, Indicates h jb The corresponding conjugate transpose, h jr represents the channel parameters between the jammer and the intermediate receiver.

[0019] In one embodiment, when constructing the transmitter to transmit a signal to the receiver based on the covert communication constraint function, the optimization problem of the transmission information of the transmitter and the jammer is:

[0020]

[0021] stD(P0||P1)=0

[0022] 0≤α≤1

[0023] 0≤P j0 +P j1 ≤P max

[0024] Among them, P a represents the transmission power at the transmitter, h ab represents the channel parameter between the transmitter and the receiver, P max Indicates the maximum transmit power of the jammer.

[0025] In one embodiment, solving the optimization problem to obtain transmission information of the transmitter and the jammer includes:

[0026] When the transmitter is silent, obtaining three variable parameters transmitted by the jammer at maximum transmit power;

[0027] For the optimization problem, the transmission information of the transmitter and the jammer is obtained according to the three variable parameters.

[0028] In one embodiment, the three variable parameters are defined by the following expressions:

[0029] n1=|h aw | 2

[0030]

[0031] Among them, h tr represents the channel parameters between the intermediate transmitter and the intermediate receiver, Indicates h jr The corresponding conjugate transpose, γ0, represents a preset signal-to-noise ratio of communication between the intermediate transmitter and the intermediate receiver.

[0032] In one embodiment, for the optimization problem, obtaining the transmission information of the transmitter and the jammer according to the three variable parameters includes:

[0033] Simplifying the optimization problem according to the three variable parameters to obtain a simplified optimization problem;

[0034] According to the size relationship between the three variable parameters, the transmission information of the transmitter and the jammer is obtained, wherein the transmission information includes: the transmission power of the transmitter when transmitting a signal to the receiver, the power allocation factor and the transmission power of the jammer.

[0035] In one embodiment, the optimization problem is simplified according to the three variable parameters to obtain a simplified optimization problem:

[0036]

[0037] stn1P α =(P max -P j1 )*(n2(1-α)+n3α)

[0038] 0≤α≤1

[0039] 0≤P j0 +P j1 ≤P max .

[0040] In one embodiment, the method further includes: the intermediate transmitter and the intermediate receiver satisfying a preset communication quality.

[0041] In a second aspect, an embodiment of the present invention provides a covert communication device based on the assistance of an intermediate node, which is applied to a covert communication system. The covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver. The device includes:

[0042] A communication parameter acquisition module, configured to acquire a plurality of communication parameters, wherein the plurality of communication parameters at least include: communication parameters between the monitoring party and the intermediate transmitter, the jammer, and the transmitter respectively;

[0043] A covert communication constraint function determination module, configured to determine a covert communication constraint function based on a plurality of communication parameters;

[0044] an optimization problem construction module, configured to construct, based on the covert communication constraint function, an optimization problem of transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver;

[0045] A solution module is used to solve the optimization problem and obtain the transmission information of the transmitter and the jammer.

[0046] The technical solution provided by the embodiment of the present invention has the following advantages compared with the prior art:

[0047] An embodiment of the present invention provides a covert communication method based on the assistance of an intermediate node, which is applied to a covert communication system. The covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver. A covert communication constraint function is determined based on the multiple communication parameters by obtaining multiple communication parameters, wherein the multiple communication parameters include at least the communication parameters between the monitor and the intermediate transmitter, the jammer, and the transmitter, respectively. Based on the covert communication constraint function, an optimization problem is constructed for the transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver. The optimization problem is solved to obtain the transmission information of the transmitter and the jammer. In this way, when the transmitter sends a signal to the receiver, the monitor can monitor whether the transmitter sends information to the receiver, taking into account the impact of the intermediate transmitter's signal transmission on the monitor. This fully utilizes the network resources in the covert communication system, thereby efficiently achieving covert communication between the transmitter and the communicating party. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0050] Figure 1 A schematic diagram of a flow chart of a covert communication method based on the assistance of an intermediate node provided by an embodiment of the present invention;

[0051] Figure 2 A schematic structural diagram of a covert communication device based on the assistance of an intermediate node provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0053] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0054] The exponential growth of the number of devices on the internet has increased the need for privacy and anti-eavesdropping security. Traditionally, wireless networks have been able to protect messages from eavesdropping attacks by using encryption and physical layer security when transmitting messages from a transmitter to a receiver. However, in some cases, it is necessary to protect not only the content of the transmitted message but also the communication process itself. In such cases, low-detection or covert communication methods can be used to prevent unauthorized monitoring.

[0055] In the prior art, covert communication is achieved by exploiting the uncertainty of the Willie decoder of an illegal monitoring party. This is to conceal the communication between the transmitter Alice and the receiver Bob. Specifically, a jammer generates and transmits artificial noise. This artificial noise, combined with channel noise, confuses the illegal monitoring party, enabling covert communication between the transmitter Alice and the receiver Bob.

[0056] As covert communication research deepens, its application scope continues to expand, encompassing diverse areas such as relay networks, drone networks, and the Internet of Things. In these networks, the surge in the number of frequency-using devices and the widespread adoption of wireless communication technologies has led to a surge in the number of unrelated nodes, making the electromagnetic environment more complex. However, existing technologies primarily focus on the legitimate participants in the covert transmission process, Alice (transmitter) and Bob (receiver), as well as illicit monitoring parties, while ignoring the potential impact of unrelated nodes (other transmitters and receivers) on communication. This results in underutilized network resources and, consequently, inefficiency in achieving covert communication.

[0057] Therefore, the present invention provides a covert communication method based on the assistance of an intermediate node, which is applied to a covert communication system. The covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver. By obtaining multiple communication parameters, wherein the multiple communication parameters include at least the communication parameters between the monitor and the intermediate transmitter, the jammer, and the transmitter, respectively, a covert communication constraint function is determined based on the multiple communication parameters. Based on the covert communication constraint function, an optimization problem is constructed for the transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver. The optimization problem is solved to obtain the transmission information of the transmitter and the jammer. In this way, when the transmitter sends a signal to the receiver, the monitor can monitor whether the transmitter sends information to the receiver, taking into account the impact of the intermediate transmitter's signal transmission on the monitor. This fully utilizes the network resources in the covert communication system, thereby effectively achieving covert communication between the transmitter and the communicating party.

[0058] In one embodiment, Figure 1 As shown, Figure 1 A flow chart of a covert communication method based on the assistance of an intermediate node provided in an embodiment of the present invention is applied to a covert communication system. The covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver. Specifically, the following steps are included:

[0059] S10: Acquire multiple communication parameters.

[0060] Among them, the multiple communication parameters include at least: communication parameters between the monitoring party and the intermediate transmitter, the jammer and the transmitter respectively; the communication parameters include: the transmission power of the intermediate transmitter when the transmitter is silent, the channel parameters between the intermediate transmitter and the monitoring party, the power allocation factor, the transmission power of the jammer when the transmitter is silent, the channel parameters between the jammer and the monitoring party, the beam between the jammer and the intermediate receiver, the number of antennas of the multi-antenna equipped with the jammer, the beam between the jammer and the monitoring party, the noise variance at the monitoring party, the transmission power of the transmitter, the channel parameters between the transmitter and the monitoring party, the transmission power of the intermediate transmitter when the transmitter sends a signal, the channel parameters between the intermediate transmitter and the monitoring party, and the transmission power of the jammer when the transmitter sends a signal.

[0061] It should be noted that transmitter silence refers to the transmitter not sending a signal to the receiver to transmit a message, denoted as event H0. Optionally, the transmitter sending a signal is denoted as event H1. The transmitter, receiver, monitor, intermediate transmitter, and intermediate receiver are all equipped with a single antenna. The jammer is equipped with multiple antennas, denoted by the number of antennas L. Communication between the transmitter and receiver does not interfere with communication between the intermediate transmitter and intermediate receiver.

[0062] Optionally, based on the above embodiment, in some embodiments of the present invention, the intermediate transmitter and the intermediate receiver meet the preset communication quality, and the preset communication quality is measured by the signal-to-noise ratio γ0, that is, the signal-to-noise ratio γ between the intermediate transmitter and the intermediate receiver is r , must satisfy γ r ≥γ0.

[0063] Specifically, in a covert communication system, for a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver, communication parameters between the monitor and the intermediate transmitter, the jammer, and the transmitter are obtained.

[0064] S11: Determine a covert communication constraint function based on multiple communication parameters.

[0065] Specifically, after obtaining the communication parameters between the monitoring party and the intermediate transmitter, the jammer, and the transmitter respectively, a covert communication constraint function is determined according to the multiple communication parameters.

[0066] Optionally, based on the above embodiment, in some embodiments of the present invention, the covert communication constraint function may be defined by the following expression based on multiple communication parameters:

[0067]

[0068] Among them, P t0 represents the transmission power of the intermediate transmitter when the transmitter is silent, h tw represents the channel parameters between the intermediate transmitter and the monitoring party, α represents the power allocation factor, P j0 Indicates the transmit power of the jammer when the transmitter is silent, h jw Indicates the channel parameters between the jammer and the monitoring party, Indicates h jw The corresponding conjugate transpose, w r represents the beam between the jammer and the intermediate receiver, L represents the number of antennas equipped by the jammer, and w w represents the beams of the jammer and the monitoring party, represents the noise variance at the monitoring site, P a Indicates the transmission power at the transmitter, h aw represents the channel parameters between the transmitter and the monitor, P t1 It represents the transmission power of the middle transmitter when the transmitter sends the signal, h tw represents the channel parameters between the intermediate transmitter and the monitoring party, P j1 Indicates the transmit power of the jammer when the transmitter sends a signal.

[0069] Optionally, based on the above embodiment, in some embodiments of the present invention, the beam between the jammer and the intermediate receiver is: a beam when a noise signal is sent in a channel null space between the jammer and the intermediate receiver by using a double zero-forcing beamforming method;

[0070] The beams of the jammer and the monitoring party are: beams when noise signals are sent in the channel null space of the jammer and the monitoring party by using a double zero-forcing beamforming method.

[0071] The beams between the jammer and the central receiver are defined by the following expressions:

[0072]

[0073] Among them, I N represents the unit matrix of dimension L, h jb represents the channel parameters between the jammer and the receiver, Indicates h jb The corresponding conjugate transpose, h jr represents the channel parameters between the jammer and the intermediate receiver.

[0074] In this way, the noise signal is sent through the dual zero-forcing beamforming method, so that the noise signal of the channel null space between the jammer and the receiver and the channel null space between the jammer and the intermediate receiver can be adjusted, thereby changing the interference power of the monitoring party, achieving a better interference effect on the monitoring party, and improving the covert communication performance between the transmitter and the receiver.

[0075] S12: Based on the covert communication constraint function, construct the optimization problem of the transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver.

[0076] Specifically, after determining the covert communication constraint function, the optimization problem of the transmission information of the transmitter and the jammer when transmitting the signal to the receiver is constructed according to the determined covert communication constraint function.

[0077] Optionally, based on the above embodiment, in some embodiments of the present invention, when constructing the optimization problem of the transmission information of the transmitter and the jammer when transmitting a signal from the transmitter to the receiver according to the covert communication constraint function, the problem is:

[0078]

[0079] stD(P0||P1)=0

[0080] 0≤α≤1

[0081] 0≤P j0 +P j1 ≤P max

[0082] Among them, P a Indicates the transmission power at the transmitter, h ab represents the channel parameters between the transmitter and the receiver, P max Indicates the maximum transmit power of the jammer.

[0083] S13: Solve the optimization problem and obtain the transmission information of the transmitter and the jammer.

[0084] The transmission information refers to the transmission power of the transmitter, the transmission power of the jammer, and the power allocation factor when the transmitter sends a signal transmission message to the receiver.

[0085] Specifically, after obtaining the optimization problem of the transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver, the optimization problem is solved to obtain the transmission information of the transmitter and the jammer when the transmitter sends a signal transmission message to the receiver.

[0086] Optionally, based on the above embodiment, in some embodiments of the present invention, an implementation of S13 may be:

[0087] S131: When the transmitter is silent, obtain three variable parameters transmitted by the jammer at the maximum transmission power.

[0088] Specifically, when the transmitter is silent, that is, when the transmitter does not send a signal transmission message to the receiver, the jammer transmits a transmission signal at a maximum transmission power, and three variable parameters transmitted by the jammer at the maximum transmission power are obtained.

[0089] Optionally, based on the above embodiment, in some embodiments of the present invention, the three variable parameters are defined by the following expressions respectively:

[0090] n1=|h aw | 2

[0091]

[0092] Among them, w w represents the beam between the jammer and the monitoring party, L represents the number of antennas equipped by the jammer, h tw represents the channel parameters between the intermediate transmitter and the monitoring party, h tr represents the channel parameter between the intermediate transmitter and the intermediate receiver, γ0 represents the preset signal-to-noise ratio of the communication between the intermediate transmitter and the intermediate receiver, Indicates h jr The corresponding conjugate transpose, w r Represents the beams of the jammer and the middle receiver.

[0093] S132: For the optimization problem, obtain the transmission information of the transmitter and the jammer according to the three variable parameters.

[0094] Specifically, for the optimization problem, the transmission information of the transmitter and the jammer is obtained according to the three obtained variable parameters.

[0095] Optionally, based on the above embodiment, in some embodiments of the present invention, an implementation of S131 may be:

[0096] S1311: Simplify the optimization problem according to the three variable parameters to obtain a simplified optimization problem.

[0097] Optionally, based on the above embodiment, in some embodiments of the present invention, the simplified optimization problem can be defined by the following expression:

[0098]

[0099] stn1P α =(P max -P j1 )*(n2(1-α)+n3α)

[0100] 0≤α≤1

[0101] 0≤P j0 +P j1 ≤P max .

[0102] Among them, P a Indicates the transmission power at the transmitter, P max represents the maximum transmission power of the jammer, α represents the power allocation factor, n1, n2 and n3 represent three variable parameters, P j0 Indicates the transmit power of the jammer when the transmitter is silent, P j1 Indicates the transmit power of the jammer when the transmitter sends a signal.

[0103] S1312: According to the size relationship between the three variable parameters, the transmission information of the transmitter and the jammer is obtained.

[0104] The transmission information includes the transmission power of the transmitter, the transmission power of the jammer, and the power allocation factor when the transmitter sends a signal transmission message to the receiver.

[0105] Specifically, a size comparison relationship between three variable parameters is set, and the transmission information of the transmitter and the jammer is obtained according to the size comparison relationship between the three variable parameters.

[0106] Optionally, based on the above embodiment, in some embodiments of the present invention, an implementation method for obtaining the transmission information of the transmitter and the jammer according to the size comparison relationship between the three variable parameters may be:

[0107] When n1 <min{n2,n3}时,且P j1 =P max , the covert communication rate is 0, then determine α=0, P α =0.

[0108] Optionally, based on the above embodiment, in some embodiments of the present invention, another implementation method for obtaining the transmission information of the transmitter and the jammer based on the size comparison relationship between the three variable parameters may be:

[0109] When min{n2, n3}≤n1≤max{n2, n3}, P j1 = 0, and there exists a solution that minimizes (n1-k), where k = n2(1-α) + n3α, and determines When n2=n3, there exists min{n2,n3}=max{n2,n3}=n2=n3, then when n1 <n2时,确定α=0,P α =P max , then when n1>n2, determine α=1, P α =P max .

[0110] Optionally, based on the above embodiment, in some embodiments of the present invention, another implementation method for obtaining the transmission information of the transmitter and the jammer based on the size comparison relationship between the three variable parameters may be:

[0111] When n1>max{n2,n3}, and P j1 =0, then determine α=1,

[0112] Thus, the method for covert communication based on the assistance of intermediate nodes provided in the embodiment is applied to a covert communication system, and the covert communication system includes a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter and an intermediate receiver. A plurality of communication parameters are acquired, wherein the plurality of communication parameters at least include communication parameters between the monitor and the intermediate transmitter, the jammer and the transmitter respectively. A covert communication constraint function is determined according to the plurality of communication parameters. An optimization problem of transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver is constructed according to the covert communication constraint function. The transmission information of the transmitter and the jammer is acquired by solving the optimization problem. In this way, when the transmitter transmits a signal to the receiver, the monitor can monitor whether the transmitter transmits information to the receiver, and the influence of the intermediate transmitter on the monitor is considered, so that the network resources in the covert communication system are fully utilized, and the covert communication between the transmitter and the receiver is efficiently implemented.

[0113] It should be understood that although Figure 1 the steps in the flowcharts are shown in a sequential order, such steps are not necessarily performed in the order shown by the arrows. Unless explicitly stated, the steps are not necessarily performed in the order shown in the flowcharts. The steps can be performed in other orders. Moreover, Figure 1 at least part of the steps in the flowcharts can include a plurality of sub-steps or a plurality of stages, which are not necessarily performed at the same time, but can be performed at different times. The order of the execution of the sub-steps or stages is not necessarily sequential, but can be performed alternately or alternately with at least part of other steps or sub-steps or stages of other steps.

[0114] In one embodiment, as shown in Figure 2 a device for covert communication based on the assistance of intermediate nodes is provided, which is applied to a covert communication system including a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter and an intermediate receiver. The device includes a communication parameter acquisition module 10, a covert communication constraint function determination module 11, an optimization problem construction module 12 and a solving module 13.

[0115] The communication parameter acquisition module 10 is configured to acquire a plurality of communication parameters, wherein the plurality of communication parameters at least include communication parameters between the monitor and the intermediate transmitter, the jammer and the transmitter respectively.

[0116] The covert communication constraint function determination module 11 is configured to determine a covert communication constraint function according to the plurality of communication parameters.

[0117] The optimization problem construction module 12 is configured to construct an optimization problem of the transmission information of the transmitter and the jammer when the transmitter transmits the signal to the receiver according to the covert communication constraint function.

[0118] The solving module 13 is configured to solve the optimization problem to obtain the transmission information of the transmitter and the jammer.

[0119] In the above embodiment, in the covert communication system, the communication parameter acquisition module acquires a plurality of communication parameters, wherein the plurality of communication parameters at least include communication parameters between the monitor, the intermediate transmitter, the jammer and the transmitter. The covert communication constraint function determination module determines the covert communication constraint function according to the plurality of communication parameters. The optimization problem construction module constructs an optimization problem of the transmission information of the transmitter and the jammer when the transmitter transmits the signal to the receiver according to the covert communication constraint function. The solving module solves the optimization problem to obtain the transmission information of the transmitter and the jammer. In this way, when the transmitter transmits the signal to the receiver, the monitor monitors whether the transmitter transmits information to the receiver, and the influence of the intermediate transmitter on the monitor is considered, so that the network resources in the covert communication system are fully utilized, and the covert communication between the transmitter and the receiver is efficiently implemented.

[0120] The specific limitations of the covert communication device based on the intermediate node assistance can be referred to the limitations of the covert communication method based on the intermediate node assistance, which will not be repeated here. The above-mentioned modules in the server can be realized by software, hardware and their combinations in whole or in part. The above-mentioned modules can be embedded in or independent of the processor in the computer device in hardware form, or stored in the memory in the computer device in software form, so as to be called and executed by the processor to perform the operations corresponding to the above-mentioned modules.

[0121] Those skilled in the art will appreciate that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static random access memory (SRAM) and dynamic random access memory (DRAM).

[0122] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0123] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A covert communication method based on the assistance of an intermediate node, characterized in that: Applied to a covert communication system, the covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver, the method includes: Acquire multiple communication parameters, wherein the multiple communication parameters at least include: communication parameters between the monitoring party and the intermediate transmitter, the jammer, and the transmitter respectively; determining a covert communication constraint function based on a plurality of communication parameters; According to the covert communication constraint function, constructing an optimization problem of transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver; The optimization problem is solved to obtain transmission information of the transmitter and the jammer.

2. The method according to claim 1, characterized in that The covert communication constraint function is defined by the following expression: Among them, P t0 represents the transmission power of the intermediate transmitter when the transmitter is silent, h tw represents the channel parameters between the intermediate transmitter and the monitoring party, α represents the power allocation factor, P j0 represents the transmit power of the jammer when the transmitter is silent, h jw represents the channel parameters between the jammer and the monitoring party, Indicates h jw The corresponding conjugate transpose, w r represents the beam between the jammer and the intermediate receiver, L represents the number of antennas equipped by the jammer, and w w represents the beams of the jammer and the monitoring party, represents the noise variance at the monitoring point, P a represents the transmission power at the transmitter, h aw represents the channel parameter between the transmitter and the monitoring party, P t1 represents the transmission power of the intermediate transmitter when the transmitter sends a signal, h tw represents the channel parameter between the intermediate transmitter and the monitoring party, P j1 Indicates the transmit power of the jammer when the transmitter sends a signal.

3. The method according to claim 2, characterized in that The method further includes: the beam between the jammer and the intermediate receiver is: a beam when a noise signal is transmitted in a channel null space between the jammer and the intermediate receiver by a double zero-forcing beamforming method; The beams of the jammer and the monitoring party are: beams formed when a noise signal is transmitted in a channel null space between the jammer and the monitoring party by a double zero-forcing beamforming method; The beams between the jammer and the intermediate receiver are defined by the following expression: Among them, I N represents the unit matrix of dimension L, h jb represents the channel parameters between the jammer and the receiver, Indicates h jb The corresponding conjugate transpose, h jr represents the channel parameters between the jammer and the intermediate receiver.

4. The method according to claim 3, characterized in that When constructing the transmitter to transmit a signal to the receiver based on the covert communication constraint function, the optimization problem of the transmission information of the transmitter and the jammer is: stD(P0||P1)=0 0≤α≤1 0≤P j0 +P j1 ≤P max Among them, P a represents the transmission power at the transmitter, h ab represents the channel parameter between the transmitter and the receiver, P max Indicates the maximum transmit power of the jammer.

5. The method according to claim 4, characterized in that The solving the optimization problem to obtain the transmission information of the transmitter and the jammer includes: When the transmitter is silent, obtaining three variable parameters transmitted by the jammer at maximum transmit power; For the optimization problem, the transmission information of the transmitter and the jammer is obtained according to the three variable parameters.

6. The method according to claim 5, characterized in that The three variable parameters are defined by the following expressions: n1=|h aw | 2 Among them, h tr represents the channel parameters between the intermediate transmitter and the intermediate receiver, Indicates h jr The corresponding conjugate transpose, γ0, represents a preset signal-to-noise ratio of communication between the intermediate transmitter and the intermediate receiver.

7. The method according to claim 6, characterized in that For the optimization problem, obtaining the transmission information of the transmitter and the jammer according to the three variable parameters includes: Simplifying the optimization problem according to the three variable parameters to obtain a simplified optimization problem; According to the size relationship between the three variable parameters, the transmission information of the transmitter and the jammer is obtained, wherein the transmission information includes: the transmission power of the transmitter when transmitting a signal to the receiver, the power allocation factor and the transmission power of the jammer.

8. The method according to claim 7, characterized in that The optimization problem is simplified according to the three variable parameters, and the simplified optimization problem is obtained as follows: s.t.n1P α =(P max -P j1 )*(n2(1-α)+n3α) 0≤α≤1 0≤P j0 +P j1 ≤P max 。 9. The method according to claim 1, characterized in that The method further includes: the intermediate transmitter and the intermediate receiver satisfying a preset communication quality.

10. A covert communication device based on the assistance of an intermediate node, characterized in that: Applied to a covert communication system, the covert communication system includes: a transmitter, a receiver, a monitor, a jammer, an intermediate transmitter, and an intermediate receiver, and the device includes: A communication parameter acquisition module, configured to acquire a plurality of communication parameters, wherein the plurality of communication parameters at least include: communication parameters between the monitoring party and the intermediate transmitter, the jammer, and the transmitter respectively; A covert communication constraint function determination module, configured to determine a covert communication constraint function based on a plurality of communication parameters; an optimization problem construction module, configured to construct, based on the covert communication constraint function, an optimization problem of transmission information of the transmitter and the jammer when the transmitter transmits a signal to the receiver; A solution module is used to solve the optimization problem and obtain the transmission information of the transmitter and the jammer.

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