CN114337977B - An anti-eavesdropping solution based on half-duplex cooperative NOMA system - Google Patents

Abstract

The application is directed to an anti-eavesdropping scheme based on a half-duplex cooperation NOMA system, which belongs to the field of wireless mobile communication, and comprises the following steps: the base station sends the superposition signal of the relay user and the remote user to the relay user; the relay user receives the signal from the base station and decodes the signal by adopting SIC; the relay user sends a new remote user superposition coded signal, the remote user and an eavesdropper receive the signal from the relay user, the remote user decodes the signal by using SIC, and the eavesdropper decodes the received signal by using PLC; obtaining the achievable rates of legal users and eavesdroppers to obtain the confidentiality rate of the remote users according to a shannon formula, and then obtaining a closed expression of the safe interruption probability of the remote users through numerical calculation; and deducing the minimum anti-eavesdrop service quality requirement of the remote user according to the service quality requirement when the remote user is just free from interruption. The scheme can effectively prevent the remote user from being eavesdropped.

Description

An anti-eavesdropping solution based on half-duplex collaborative NOMA system

Technical field

The invention belongs to the field of wireless mobile communications. The main application scenario is a half-duplex cooperative NOMA system. The main application is to prevent the signal of a remote user from being eavesdropped. Specifically, it relates to the analysis of the security interruption probability of a single eavesdropper half-duplex cooperative NOMA system. Minimum quality of service requirements to prevent users from being eavesdropped.

Background technique

In view of the rapid development of the Internet and IoT services, the business demand for wireless communications is growing day by day. Non-orthogonal multiple access (NOMA) technology, as one of the promising key technologies in the fifth generation wireless network, has been widely used in various fields. Different from the previous Orthogonal Multiple Access (OMA) technology, only a single wireless resource can be allocated to a user, for example, divided according to frequency or time. NOMA technology allows serving multiple users simultaneously with different powers in the same resource block (time/frequency/coding). The receiving end uses serial interference cancel (Successive interference cancel, SIC) to eliminate interference from other users based on the power difference for decoding.

Cooperative transmission technology is an effective technology to combat path loss, channel fading and shadow effects. It can form a virtual multiple-input multiple-output scheme, collaboratively process data, and improve communication reliability for users with poor channel conditions. In a cooperative communication system, relay nodes are used to forward signals from source nodes, which is called cooperative diversity. The working mode of the relay node can be divided into full-duplex mode and half-duplex mode. Due to the broadcast nature of wireless communications, physical layer security has attracted widespread attention in recent years as an attractive method for achieving secure communications. Therefore, how to prevent user signals from being eavesdropped is the main direction of current research.

To sum up, the problem with the existing technology is that although the security analysis of cooperative NOMA systems is a major research hotspot, there is currently relatively little research on anti-eavesdropping solutions for users in half-duplex cooperative NOMA systems.

Difficulty in solving the above problem: Obtain a closed-form expression for the safe interruption probability in a single-eavesdropper half-duplex cooperative NOMA system, so as to derive the service quality requirements of the remote user when no interruption occurs, thereby preventing the remote user signal from being eavesdropped .

The significance of solving the above problems: Obtain closed-form expressions for the interruption probability of relay users and the safe interruption probability of remote users in half-duplex cooperative NOMA systems, and quantitatively understand the security performance of half-duplex cooperative NOMA systems based on single eavesdroppers. , deducing the situation in which the user does not experience interruption, thereby effectively preventing the remote user's signal from being eavesdropped.

Contents of the invention

In view of the problems existing in the existing technology, the present invention provides an anti-eavesdropping solution based on the half-duplex cooperative NOMA system, which is used to prevent the remote user's signal leakage and ensure the remote user's information security.

In the first aspect, this application provides an anti-eavesdropping solution based on the half-duplex collaborative NOMA system. The method includes:

S1. The base station sends the superimposed coded signal about the relay user and the remote user to the relay user;

S2. The relay user receives the signal from the base station and decodes it using serial interference cancellation SIC;

S3. The relay user sends a new remote user superimposed coded signal;

S4. The remote user and the eavesdropper receive the signal from the relay user. The remote user uses SIC to decode the signal, and the eavesdropper uses parallel interference cancellation PLC to decode and receive the signal;

S5. According to the Shannon formula, obtain the achievable rates of legitimate users and eavesdroppers;

S6. Obtain the confidentiality rate of the remote user, and then obtain the closed-form expression of the security interruption probability of the remote user through numerical calculation;

S7. Based on the service quality requirements of the remote user when no interruption occurs, derive the minimum anti-eavesdropping service quality requirements of the remote user.

Further, the method also includes:

When a near-end user acts as a relay, it is assumed that the transmit power of the relay user is consistent with the transmit power of the base station.

Further, the method includes:

Due to distance, obstacles or other practical reasons, there is no direct link between the remote user and the eavesdropper and the base station.

Further, the method includes:

The S2 includes:

S21: After receiving the signal from the base station, the relay user needs to first decode the signal of the farthest user, then decode the signal of the secondary remote user, and finally decode its own signal according to the different power allocation.

S22: According to the decoding sequence, obtain the signal to interference plus noise ratio (SINR) when the relay user decodes the relay user and remote user signals respectively.

Further, the method includes:

The relay user operates in half-duplex mode to decode and forward the superimposed coded signal of the new remote user.

Further, the method includes:

When calculating the user's achievable rate, the channel bandwidth considered in S5 is the unit bandwidth.

Further, the method includes:

For relay users, only when the relay user successfully decodes the signals of the remote user and the relay user at the same time, no interruption will occur. The safe interruption probability of the S6 remote user is that the rate of the remote user is less than the user's quality of service. Required supplement.

Description of the drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic diagram of a single eavesdropper half-duplex cooperative NOMA system scenario provided by the implementation of the present invention.

Figure 2 is a flow chart of safety interruption probability analysis provided by the implementation of the present invention.

Detailed ways

The following describes the embodiments of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. The following embodiments and the features in the embodiments can be combined with each other as long as there is no conflict.

The drawings are only for illustrative purposes and represent only schematic diagrams rather than actual drawings, which cannot be understood as limitations of the present invention. For those skilled in the art, some known structures and their descriptions may be omitted in the drawings. It's understandable.

The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

The security interruption probability analysis in the single-eavesdropper half-duplex cooperative NOMA system provided by this application is implemented in the scenario of Figure 1. Among them, BS represents the relay, UE ₁ represents the central user, which is also the relay user, UE ₂ represents the secondary remote user, UE ₃ represents the farthest user, and E represents the eavesdropper. h _r represents the channel parameters between the base station and the relay user, h _1,i , represent the channel parameters between the central user and UE ₂ , UE ₃ and the eavesdropper respectively, and it is assumed that the channel gains obey exponential distribution.

The security interruption probability analysis method in the single eavesdropper half-duplex cooperative NOMA system provided by the implementation of the present invention specifically includes the following steps:

S1. The base station sends a superimposed coded signal about the relay user and the remote user to the relay user. The superimposed signal sent by the base station can be expressed as:

Among them, x ₁ , x ₂ , and x ₃ respectively represent the signals of the relay user, the secondary remote user and the most remote user, and P _s is the transmit power of the base station.

S2. The relay user receives the signal from the base station and uses serial interference cancellation SIC for decoding. The signal received by the relay user can be expressed as:

y _r ＝h _r x+n ₁ (2)

Then the relay user uses SIC to decode the received signal. For the half-duplex working mode, the relay user decodes the farthest user signal, the secondary remote user signal and the relay user in sequence, and the SINR when decoding the signal They are:

γ ₁ ＝a ₁ |h _r | ² ρ (5)

in Indicates the signal-to-noise ratio (SNR) of the base station.

S3. The relay user sends a new remote user superimposed coded signal, then the superimposed signal forwarded by the relay user is:

Where P _r is the transmission power of the relay user, and P _r =P _s , Indicates the SNR at the relay user.

S4. The remote user and the eavesdropper receive the signal from the relay user. The remote user uses SIC to decode the signal, and the eavesdropper uses parallel interference cancellation PLC to decode and receive the signal. Specifically, due to the broadcast nature of wireless transmission, users in the community will receive signals forwarded from the central user. Naturally, remote users and eavesdroppers will also receive signals from remote users. The signal received by the farthest user from the relay user is:

y ₃ =h _{1, 3} y+n ₃ (7)

The SINR of the farthest user’s decoded signal is:

The signal received by the secondary remote user from the relay user is:

y ₂ = h _{1, 2} y+n ₂ (9)

The sub-remote user uses SIC to decode the signal. The SINR of the sub-remote user decoding the farthest user signal and the sub-remote user signal are respectively

γ ₂ =b ₁ |h _1,2 | ² ρ (11)

The signal received by the eavesdropper from the relay user is:

y _e =h _1,e y+n _e (12)

Then the eavesdropper decodes the received signal through parallel interference cancellation (PLC). Then the SINR of the remote user signal decoded at the eavesdropper is:

S5. According to Shannon's formula, obtain the achievable rates of legitimate users and eavesdroppers. For eavesdroppers, their rates can be expressed as

For legitimate users, when the relay user works in half-duplex mode, the achievable rates of the secondary remote user and the most remote user are:

S6. Obtain the remote user's confidentiality rate, and then obtain the closed-form expression of the remote user's security interruption probability through numerical calculation, where the remote user's confidentiality rate is:

Among them [x] ⁺ =max{x,0}. Then the closed-form expression of the outage probability of the system is obtained through numerical calculation. Specifically, they are the outage probability of the relay user and the safe outage probability of the remote user.

The first step is to calculate the interruption probability of the relay user. The relay user will not be interrupted until the remote user's signal and the relay user's signal are successfully decoded at the same time. When the relay user works in half-duplex mode, the relay user will not be interrupted. The outage probability of subsequent users can be expressed as:

in Indicates the user's service quality requirements, and λ _r indicates that the channel gain between the base station and the relay user obeys an exponential distribution with parameter λ _r .

The second step is to calculate the remote user's secure interruption probability. The remote user's confidential interruption probability is the complement of the remote user's rate that is lower than the user's quality of service requirements. When the relay user works in half-duplex mode, the remote user's The safety outage probability can be specifically expressed as:

It is currently difficult to obtain a closed-form solution to formula (1), so considering the situation of high signal-to-noise ratio, when SNR tends to infinity, Therefore:

in Then the security interruption probability of the single eavesdropper half-duplex cooperative NOMA system is:

S7. Based on the service quality requirements of the remote user when no interruption occurs, derive the minimum anti-eavesdropping service quality requirements of the remote user. After studying the data transmission process, it was found that since the safe interruption probability is calculated, when no interruption occurs at the remote user, the eavesdropper must not steal the remote user's signal. Through calculation, it can be found that when the remote user's service When the quality requirements meet the following conditions,

It can effectively prevent remote user signal leakage.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified. Modifications or equivalent substitutions without departing from the purpose and scope of the technical solution shall be included in the scope of the claims of the present invention.

Claims (7)

1. An anti-eavesdropping scheme based on a half-duplex cooperative NOMA system, characterized in that the anti-eavesdropping scheme based on a single eavesdropper half-duplex cooperative NOMA system comprises:

s1, a base station sends superposition coded signals about a relay user and a remote user to the relay user;

s2, the relay user receives signals from the base station and decodes the signals by adopting SIC;

s3, the relay user sends a new remote user superposition coded signal;

s4, the remote user and an eavesdropper receive signals from the relay user, the remote user decodes the signals by using SIC, and the eavesdropper decodes the received signals by using PLC;

s5, obtaining the achievable rates of legal users and eavesdroppers according to a shannon formula;

s6, obtaining the confidentiality rate of the remote user, and then obtaining a closed expression of the security interruption probability of the remote user through numerical calculation;

s7, deducing the minimum anti-eavesdrop service quality requirement of the remote user according to the service quality requirement when the remote user is just free from interruption.

2. An anti-eavesdropping scheme according to claim 1, wherein when the near-end user acts as a relay, it is assumed that the transmission power of the relay user coincides with the transmission power of the base station.

3. An anti-eavesdropping scheme according to claim 1, characterized in that there is no direct link between the remote user and the eavesdropper and the base station due to distance, obstructions or other real reasons.

4. An anti-eavesdropping scheme according to claim 1, wherein S2 comprises:

s21, after receiving signals from a base station, a relay user needs to decode signals of the most remote user firstly, then decodes signals of the secondary remote user and finally decodes signals of the relay user according to different power distribution sizes;

s22, according to the decoding sequence, SINR when the signals of the relay user and the remote user are respectively decoded at the relay user is obtained.

5. An anti-eavesdropping scheme according to claim 1 wherein the relay user operates in half duplex mode to decode and forward the superimposed coded signal of the new remote user.

6. An anti-eavesdropping scheme according to claim 1, wherein the channel bandwidth considered in S5 is a unit bandwidth when calculating the achievable rate of the user.

7. An anti-eavesdropping scheme according to claim 1, wherein for the relay user, only the relay user will successfully decode the signals of the remote user and the relay user at the same time without interruption, and the S6 probability of interruption of the security of the remote user is that the rate of the remote user is less than the complement of the user' S service quality requirement.