Secure communication method of eavesdropping NOMA network based on artificial noise

Abstract

The invention discloses a secure communication method of an eavesdropping NOMA network based on artificial noise, which comprises the following steps: in a first time slot, an information source user sends an NOMA signal, and a relay user selected according to a maximum and minimum relay selection scheme sends an artificial noise signal to interfere with an eavesdropping user while receiving the signal; in the second time slot, the selected relay user adds the decoded signal and the artificial noise in the first time slot in an XOR mode, then constructs a signal and sends the signal, and the information source user sends the artificial noise to interfere with the eavesdropping user; and each user calculates a required signal-to-noise ratio or a signal-to-interference-and-noise ratio, and calculates a corresponding interruption probability and a corresponding eavesdropping probability. Artificial noise, relay cooperation and a one-time pad technology are combined to construct a secure communication scheme, the scheme enables an eavesdropping user to directly intercept a legal user signal only once, and in a traditional secure communication scheme, the eavesdropping user can directly obtain an information source user signal twice, so that the security of the eavesdropping user is improved. Therefore, the physical layer security of the cooperative NOMA network is effectively enhanced.

Description

Technical Field

[0001] The present invention relates to a physical layer secure communication scheme against eavesdropping attacks in a cooperative non-orthogonal multiple access (NOMA) network, belonging to the technical field of physical layer security in wireless communication, and particularly relates to combining the artificial noise technology with the traditional one-time pad technology to combat external eavesdropping attacks on a relay cooperative NOMA network. Background Art

[0002] The progress of network technology and wireless communication technology enables various terminal devices to be connected to the network. The emergence and rise of the Internet of Things further accelerate the development of this trend, resulting in an explosive growth of network data transmission and making spectrum resources more scarce. Cooperative relay technology can expand the signal coverage range, enable more users to connect to the communication network, and improve the data transmission efficiency. NOMA technology can serve multiple users simultaneously and alleviate the current shortage of spectrum resources. Therefore, the combination of relay cooperative technology and NOMA technology can enable the network to provide better services for more users. However, while the relay cooperative NOMA network serves more users, it also allows more users to be connected to the network, giving more users the opportunity to obtain legitimate user information, which poses more challenges to the current network communication security. Currently, traditional cryptography technologies rely on difficult problems in mathematics to construct secure communication schemes. Summary of the Invention

[0003] Object of the Invention: The object of the present invention is to provide a secure communication method for an eavesdropped NOMA network based on artificial noise. In the case where the relay cooperative NOMA network is attacked by external eavesdropping users, the present invention proposes a physical layer secure communication scheme. The secure communication scheme designed by the present invention based on relay selection, artificial noise, and one-time pad technology can efficiently achieve secure communication between the near user and the far user, and the security-reliability balance performance of the secure communication scheme of the present invention has a very obvious advantage over the existing secure communication schemes.

[0004] Technical Solution: A secure communication method for an eavesdropped NOMA network based on artificial noise according to the present invention is applied to a communication scenario where a cooperative non-orthogonal multiple access NOMA network with multiple relay nodes is under eavesdropping attack. The system includes a source user, several relay nodes each equipped with two antennas, a single-antenna near user, a single-antenna far user, and a single-antenna eavesdropping user. The secure communication method includes the following steps:

[0005] Step 1: In the first time slot, the source uses NOMA technology to linearly combine the near user message x 1 and the far user message x 2 to obtain a mixed signal Among them, α 1 and α 2 respectively represent the power allocation coefficients of x 1 and x 2 , α 2 >α 1 >0, α 1 +α 2 =1; Then, the source sends the NOMA signal to the relay node selected based on the max - min relay selection scheme. This relay node adopts full - duplex technology. While one antenna receives the NOMA signal, the other antenna sends the artificial noise signal x J to interfere with the eavesdropping user E; The relay node, the near user, the far user, and the eavesdropping user calculate the corresponding signal - to - noise ratio (SNR) and signal - to - interference - plus - noise ratio (SINR) according to the received signals.

[0006] Step 2: In the second time slot, the selected relay node decodes the signals x 1 and x 2 , regards x 1 , x 2 and x J as bit strings, and respectively XOR - adds x 1 and x 2 with x J to obtain the signals and Again using NOMA technology, the NOMA signal The selected relay node transmits the signal x r , and the source, as an interfering node, simultaneously transmits the artificial noise signal x J1 to weaken the eavesdropping attack; Finally, the near user, the far user, and the eavesdropping user calculate the SINR and SNR of the relevant signals according to their respective received signals; Considering the worst - case scenario, assume that the eavesdropping user is a strong eavesdropper, so the eavesdropping user ignores the serial interference between NOMA signals.

[0007] Step 3: The near user, the far user, and the eavesdropping user calculate the corresponding outage probability and eavesdropping probability according to the obtained SINR and SNR.

[0008] Furthermore, in Step 1, the selected relay node R i in the first time slot can obtain the SINRs of the decoded signals x 2 and x 1 from the received signal x as follows:

[0009]

[0010] Among them, P s1 is the transmission power of the source signal, and the additive white Gaussian noise power at the relay node R i is hsi Denote the instantaneous channel state information from the source to the selected relay node as \(h_{s,r}\), and the residual self - interference signal - to - noise ratio of the selected relay node as \(I\). If the eavesdropping user is a strong eavesdropper, the signal - to - interference - plus - noise ratio of the eavesdropping user with respect to signals \(x\) 2 and \(x\) 1 is:

[0011]

[0012] where \(h_{r,e}\) se and \(h_{s,e}\) ie respectively represent the instantaneous channel state information from the source and the selected relay node to the eavesdropping user, \(P\) r1 is the signal transmission power of the selected relay node, and the additive white Gaussian noise power at the eavesdropping user is \(N_0\). Since the relay node adopts XOR operation, the two NOMA users and the eavesdropping user need to decode the artificial noise signal \(x\) J , so the signal - to - noise ratios of the near user and the far user with respect to the signal \(x\) J and the signal - to - interference - plus - noise ratio of the eavesdropping user for decoding the signal \(x\) J are respectively:

[0013]

[0014] where and respectively represent the instantaneous channel state information from the selected relay node to the near user and the far user, \(P_1\) r1 is the power of the artificial noise signal transmitted by the selected relay node in the first time slot, and are the Gaussian white noise powers at the near user and the far user respectively.

[0015] Furthermore, in step 1, the signal - to - interference - plus - noise ratios of the selected relay node for decoding signals \(x\) 1 and \(x\) 2 , the signal - to - interference - plus - noise ratios or signal - to - noise ratios of the NOMA users and the eavesdropping user for decoding the artificial noise signal \(x\) J are calculated as follows: First, select a relay node from the relay node set . Here, the relay selection rule is:

[0016]

[0017] While receiving the NOMA signal sent by the source, the relay node also needs to send the artificial noise signal \(x\) J to interfere with the eavesdropping user. The signal received by the relay node is:

[0018]

[0019] where \(n\) idenotes the additive white Gaussian noise at the relay node, h ii is the residual self-interference after self-interference cancellation at the relay node; the relay node calculates the signal x according to the received signal 1 and x 2 The signal-to-interference-plus-noise ratios of are respectively and The received signals of the near user, far user, and eavesdropping user are respectively:

[0020]

[0021] wherein, and n e respectively denote the additive white Gaussian noise at the near user, far user, and eavesdropping user; the near user, far user, and eavesdropping user calculate the signal-to-noise ratio and signal-to-interference-plus-noise ratio of the corresponding signals as respectively and

[0022] Further, in step 2, in the second time slot, the near user decodes the signals and The signal-to-interference-plus-noise ratio and signal-to-noise ratio of are respectively:

[0023]

[0024] wherein, P r2 denotes the transmit power of the second time slot signal of the selected relay node; the far user decodes the signal The signal-to-interference-plus-noise ratio of is:

[0025]

[0026] Based on the fact that the eavesdropping user has strong eavesdropping ability, the signal-to-interference-plus-noise ratio of the eavesdropping user with respect to the signals and is:

[0027]

[0028] wherein, P s2 denotes the power of the artificial noise transmitted by the source user in the second time slot.

[0029] Further, in step 2, in the second time slot, the process of calculating the signal-to-interference-plus-noise ratio and signal-to-noise ratio of the relevant signals is as follows: the relay node XOR-adds the decoded signals x 1 and x 2 with the artificial noise signal x J transmitted in its first time slot, and then adopts the NOMA technology to obtain the mixed signal and sends this signal to the NOMA users, and the source simultaneously sends the artificial noise x J1Weaken the eavesdropping user; thus, the received signals of the near user, far user, and eavesdropping user are respectively:

[0030]

[0031]

[0032] Combined with the NOMA mechanism, the near user decodes and The signal-to-interference-plus-noise ratios are respectively and The far user decodes The signal-to-interference-plus-noise ratio is The eavesdropping user has a strong eavesdropping ability, and its decoded signals and The signal-to-interference-plus-noise ratios are respectively and

[0033] Furthermore, in step 3, the outage probability calculation process is as follows: According to the NOMA mechanism and the relay cooperation strategy, at the end of the data transmission in the first time slot, the selected relay node needs to decode the signals x 2 and x 1 As long as and The condition for the near user to successfully decode x J is In the second time slot, according to the NOMA mechanism, as long as the near user can successfully decode Based on this analysis, the outage probability of the near user is:

[0034]

[0035] The far user needs to decode x 2 , and it requires the relay node to successfully decode x 2 and x 1 in the first time slot. It also requires the far user to decode the artificial noise signal x J in the first time slot and the signal in the second time slot. Therefore, the outage probability of the far user is:

[0036]

[0037] Furthermore, in step 3, the eavesdropping probability calculation process is as follows: There are two cases where the signal x 1 is eavesdropped. One is that the eavesdropper directly steals the source message x 1 ; the other is that the eavesdropping user cannot directly obtain x 1 , and the near user needs to decode x J and Then, based on the property of the exclusive OR operation, x is obtained1 , so the probability that the near user is wiretapped is:

[0038]

[0039] The probability that the far user is wiretapped is:

[0040]

[0041] The present invention also discloses a computer device, including a memory, a processor, and a computer program stored on the memory, and the processor executes the computer program to implement the steps of the method of the present invention.

[0042] The present invention also discloses a computer-readable storage medium, on which a computer program / instructions is stored, and when the computer program / instructions is executed by a processor, the steps of the method of the present invention are implemented.

[0043] The present invention also discloses a computer program product, including a computer program / instructions, and when the computer program / instructions is executed by a processor, the steps of the method of the present invention are implemented.

[0044] Advantageous effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0045] 1. The present invention combines cooperative relaying and NOMA technology, which can not only expand the coverage range of wireless signals, but also increase the utilization rate of spectrum resources and provide services for more users;

[0046] 2. The present invention combines a relay selection strategy, artificial noise technology, and one-time pad encryption technology to construct a secure communication scheme; compared with traditional secure communication schemes, the eavesdropping user in the present invention has only one chance to directly intercept the source message, while the eavesdropping user in the existing secure communication scheme has two chances to directly obtain the source message, so the secure communication scheme proposed by the present invention can effectively enhance the physical layer security of the system;

[0047] 3. Different from traditional cryptography technologies, physical layer security can achieve data transmission in the sense of perfect secrecy only by using the random characteristics of wireless channels or wireless signals. The present invention combines artificial noise technology and relay cooperation strategy in physical layer security technology, as well as one-time pad technology, to construct a secure communication scheme applied to cooperative NOMA networks. In the existing physical layer secure communication scheme applied to cooperative NOMA networks, the eavesdropping user has two chances to directly obtain the information of legitimate users, while the eavesdropping user in the present invention's scheme has only one chance to directly intercept the information of legitimate users, thus effectively enhancing the physical layer security of the cooperative NOMA network suffering from eavesdropping attacks. Description of the Drawings

[0048] Figure 1System model diagram of a secure communication scheme for an eavesdropping NOMA network based on artificial noise according to the present invention;

[0049] Figure 2 Flowchart of a secure communication scheme for an eavesdropping NOMA network based on artificial noise according to the present invention;

[0050] Figure 3 Comparison diagram of the security-reliability balance performance of two NOMA users between the present invention and the comparative scheme. Detailed implementation manners

[0051] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the system model diagram, the scheme flowchart, and the experimental simulation results.

[0052] As Figure 1 shown, the relay cooperative NOMA communication system model includes 1 source user, 3 relay nodes each equipped with two antennas, 1 single-antenna near user, 1 single-antenna far user, and 1 single-antenna eavesdropping user.

[0053] The process of the present invention is as Figure 2 shown,

[0054] Step 1: The source user adopts the NOMA mechanism to construct a signal and then sends the signal x to the relay node selected according to the maximum-minimum relay selection scheme. The selected relay node adopts the full-duplex mode and sends the artificial noise signal x while receiving the signal J to interfere with the eavesdropping user;

[0055] Step 2: The received signal at the selected relay node is From this, the signal-to-interference-plus-noise ratio can be calculated as and The received signals of the near user, the far user, and the eavesdropping user are respectively and Thus, the signal-to-noise ratio and the signal-to-interference-plus-noise ratio of the corresponding signals of the near user, the far user, and the eavesdropping user can be calculated as and

[0056] Step 3: If the selected relay node can decode the signals x 1 and x 2 , then x 1 , x 2 and x J are regarded as bit sequences, and and can be obtained. Then, the NOMA mechanism is adopted to obtain the mixed signal Finally, x rSent to NOMA users; if the selected relay node cannot correctly decode the source signal x 1 and x 2 , then go to step 5;

[0057] Step 4, the signals received by the near user, far user, and eavesdropping user are respectively and The near user, far user, and eavesdropping user can each calculate the corresponding signal-to-noise ratio as and

[0058] Step 5, the near user and far user calculate their respective outage probabilities based on the obtained signal-to-interference-plus-noise ratio and signal-to-noise ratio as follows:

[0059]

[0060] and

[0061]

[0062] The probabilities that the near user and far user are eavesdropped are respectively:

[0063]

[0064] and

[0065]

[0066] The following presents the use of Matlab numerical simulation experiments to implement the outage probabilities of the near user and far user, as well as their eavesdropping probabilities of being eavesdropped. In the simulation experiment, after normalizing the user distances, the coordinates of the source user are (-1,0), the coordinates of the near user and far user are (1,0) and (1,1) respectively, and the position of the eavesdropping user is (0, -1). The relay nodes are distributed on a circle centered at (0,0) with a radius equal to 0.05. The coordinates of the relay node R i are where N = 3, i = 1, 2, 3. In this cooperative NOMA network, each channel is Rayleigh faded. The additive Gaussian noise power of each user in the network is equal, all being σ 2 , and the transmission power of each node signal in the system is P, so the transmission signal-to-noise ratio is The signal-to-noise ratio of the residual self-interference signal is a constant value I = 1, the power allocation coefficient α 1 = 0.1, α 2 = 0.9, and the relevant threshold values are γ 1 = 7, γ 2 = 3, γ e= 2. Next, the security of NOMA users is characterized by the Security-reliability tradeoff (SRT).

[0067] Figure 3 This is a comparison graph of the security-reliability tradeoff performance curves of the present invention, the non-artificial noise secure communication scheme, and the traditional artificial noise secure communication scheme applied to a cooperative NOMA network suffering from eavesdropping attacks. From Figure 3 It can be seen that the security-reliability tradeoff performance of the near user and the far user of the present invention is significantly better than that of the corresponding users of the non-artificial noise secure communication scheme and the traditional artificial noise secure communication scheme.

Claims

1. A secure communication method for eavesdropping NOMA networks based on artificial noise, which is applied to communication scenarios where cooperative non-orthogonal multiple access NOMA networks with multiple relay nodes are subject to eavesdropping attacks, and is characterized in that: The system includes a source user, a plurality of relay nodes equipped with two antennas, a single-antenna near user, a single-antenna far user and a single-antenna eavesdropping user, and the secure communication method includes the following steps: Step 1: In the first time slot, the source uses NOMA technology to linearly combine the near user message x1 and the far user message x2 to obtain a mixed signal Among them, α1 and α2 represent the power allocation coefficients of x1 and x2 respectively, α2>α1>0, α1+α2=1; Then, the source sends the NOMA signal to the relay node selected based on the maximum minimum relay selection scheme. The relay node adopts full-duplex technology. While one antenna receives the NOMA signal, the other antenna sends the artificial noise signal x J Interfere with eavesdropping user E; relay nodes, near users, far users and eavesdropping users calculate the corresponding signal-to-noise ratio and signal-to-interference-to-noise ratio based on the received signal; Step 2: In the second time slot, the selected relay node decodes the signals x1 and x2 and converts x1, x2 and x J Looking at the bit string, compare x1 and x2 to x J XOR addition, get signal and Use NOMA technology again to obtain NOMA signal The selected relay node transmits signal x r , the source acts as an interference node and simultaneously transmits an artificial noise signal x J1 Weaken the eavesdropping attack; Finally, the near user, far user and eavesdropping user calculate the signal-to-noise ratio and signal-to-noise ratio of the relevant signal based on their respective received signals; Based on the worst case consideration, the eavesdropping user is assumed to be a strong eavesdropper, so that the eavesdropping user ignores the serial interference between NOMA signals; Step 3: The near user, far user and eavesdropping user calculate the corresponding interruption probability and eavesdropping probability according to the obtained signal-to-interference-plus-noise ratio and signal-to-noise ratio.

2. According to claim 1, a secure communication method for eavesdropping on NOMA networks based on artificial noise is characterized in that: In step 1, the relay node R selected in the first time slot i According to the received signal x, the signal-to-interference-noise ratios of the decoded signals x2 and x1 are obtained as follows: Among them, P s1 is the source signal transmission power, the relay node R i The additive white Gaussian noise power at is h si represents the instantaneous channel state information from the source to the selected relay node, and I is the residual self-interference signal-to-noise ratio of the selected relay node; if the eavesdropping user is a strong eavesdropper, then the signal-to-noise ratio of the eavesdropping user for signals x2 and x1 is: Among them, h se and h ie They represent the instantaneous channel state information from the source and the selected relay node to the eavesdropping user, respectively, r1 is the signal transmission power of the selected relay node, and the additive white Gaussian noise power at the eavesdropping user is Because the relay node uses XOR operation, the two NOMA users and the eavesdropping user need to decode the artificial noise signal x J , so that the near user and the far user have J The signal-to-noise ratio and the eavesdropping user's decoded signal x J The signal-to-interference-noise ratios are: in, and represents the instantaneous channel state information from the selected relay node to the near user and the far user, respectively, r1 is the power of the artificial noise signal sent by the selected relay node in the first time slot, and are the Gaussian white noise powers at the near user and the far user respectively.

3. According to claim 2, a secure communication method for eavesdropping on NOMA networks based on artificial noise is characterized in that: In step 1, the signal-to-interference-noise ratio of the decoded signals x1 and x2 of the selected relay node in the first time slot, the artificial noise signal x decoded by the NOMA user and the eavesdropping user J The signal-to-interference-to-noise ratio or signal-to-noise ratio calculation process is as follows: First, from the relay node set Select a relay node from the , where the relay selection rule is: While receiving the NOMA signal from the source, the relay node also sends an artificial noise signal x J Interfering with the eavesdropping user, the signal received by the relay node is: Among them, n i represents the additive white Gaussian noise at the relay node, h ii is the residual self-interference after the self-interference signal of the relay node is eliminated; the relay node calculates the signal-to-noise ratios of signals x1 and x2 based on the received signal and is and The received signals of the near user, far user and eavesdropping user are: in, and n e Represent the additive white Gaussian noise at the near user, far user and eavesdropping user respectively; based on the received signal, the signal-to-noise ratio and signal-to-interference-noise ratio of the corresponding signal calculated by the near user, far user and eavesdropping user are and 4. According to claim 2, a secure communication method for eavesdropping on NOMA networks based on artificial noise is characterized in that: In step 2, the second time slot near the user decoded signal and The signal-to-interference-noise ratio and signal-to-noise ratio are: Among them, P r2 Indicates the signal transmission power of the second time slot of the selected relay node; the decoded signal of the remote user The signal-to-interference-noise ratio is: Based on the strong eavesdropping ability of the eavesdropping user, we can get the eavesdropping user's information about the signal and The signal-to-interference-noise ratio is: Among them, P s2 Indicates the power of artificial noise transmitted by the source user in the second time slot.

5. According to claim 2, a secure communication method for eavesdropping on NOMA networks based on artificial noise is characterized in that: In step 2, in the second time slot, the process of calculating the signal to interference noise ratio and signal to noise ratio of the related signal is as follows: the relay node compares the decoded signals x1 and x2 with the artificial noise signal x1 sent in the first time slot. J XOR addition, and then use NOMA technology to obtain mixed signals And send the signal to NOMA users, the source also sends artificial noise x J1 Weaken the eavesdropping user; thus, the received signals of the near user, the far user and the eavesdropping user are: Combined with NOMA mechanism, near user decoding and The signal-to-interference-noise ratios are and Remote User Decoding The signal-to-interference-noise ratio is The eavesdropping user has strong eavesdropping capabilities and his decoded signal and The signal-to-interference-noise ratios are and 6. According to claim 2, a secure communication method for eavesdropping on NOMA networks based on artificial noise is characterized in that: In step 3, the interruption probability calculation process is as follows: According to the NOMA mechanism and relay cooperation strategy, the data transmission of the first time slot ends, and the selected relay node needs to decode signals x2 and x1. and Near user successfully decoded x J The condition is In the second time slot, according to the NOMA mechanism, as long as and Near users can successfully decode Based on this analysis, the probability of near user interruption is: For the far user to decode x2, the relay node needs to successfully decode x2 and x1 in the first time slot, and the far user needs to decode the artificial noise signal x in the first time slot. J and the second time slot signal Therefore, the outage probability of a remote user is:

7. According to claim 2, a secure communication method for eavesdropping on NOMA networks based on artificial noise is characterized in that: In step 3, the eavesdropping probability calculation process is as follows: There are two situations in which the signal x1 is eavesdropped. One is that the eavesdropper directly steals the source message x1; the other is that the eavesdropping user cannot directly obtain x1 and the user needs to decode x1. J and Then, we get x1 from the properties of XOR operation. Therefore, the probability of the nearby user being eavesdropped is: The probability of a remote user being eavesdropped is:

8. A computer device comprising a memory, a processor and a computer program stored in the memory, characterized in that: The processor executes the computer program to implement the steps of the method of claim 1.

9. A computer-readable storage medium having a computer program / instruction stored thereon, characterized in that: When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 are implemented.

10. A computer program product comprising a computer program / instructions, characterized in that When the computer program / instructions are executed by a processor, the steps of the method according to claim 1 are implemented.

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