A short packet secure transmission method for a multi-intelligent reflector-assisted energy harvesting system

Abstract

The present invention discloses a short packet secure transmission method for a multi-intelligent reflector-assisted energy collection system. The source node communicates with the destination node with the assistance of K intelligent reflectors and a relay node without external energy supply. Before the communication starts, with the assistance of K intelligent reflectors, the relay node collects energy from the energy signal sent by the source node. During the communication process, the maximum channel gain is selected as the goal, and #imgabs0# is selected. Under the premise of ensuring that the signal-to-noise ratio of the destination node is greater than a certain threshold, the lower bound of the safety rate is maximized to obtain the power allocation factor α of the useful signal. * Finally, with the assistance of #imgabs1# and the relay nodes, the source node uses α * As a power allocation factor, the proposed scheme optimizes the power allocation factor through the signal-to-noise ratio and the lower bound of the confidentiality rate. Under the premise of considering the certain reliability of communication, the lower bound of the short packet confidentiality transmission rate of the entire communication system is maximized to ensure the security of communication.

Description

Technical Field

[0001] The present invention relates to the field of communication technology, and in particular to a short packet secure transmission method for a multi-intelligent reflector-assisted energy collection system. Background Art

[0002] The smart reflective surface is a plane composed of a large number of low-cost passive reflective units, which is placed between the sender and the receiver. Since each reflective unit can independently change the phase of the incident signal, the wireless propagation environment can be changed by adjusting the phase shift on the reflective unit. The emergence of smart reflective surface technology breaks the traditional method of improving the performance of communication systems by designing high-performance transceivers, and will have a disruptive impact on future communication systems. Therefore, smart reflective surface technology has become a key technology for the sixth generation of mobile communications.

[0003] With the rapid growth of the number of communication devices, the carbon emission problem in the communication industry has attracted widespread attention in the industry. Energy harvesting technology based on radio frequency signals provides a new way of power supply. Communication network nodes can use energy harvesting technology to collect energy from surrounding radio frequency signals and use the energy for subsequent information transmission. The successful application of this technology will greatly reduce the carbon emissions of the communication system. Combining energy harvesting technology with smart reflective surface technology can not only improve the energy efficiency of the communication system and reduce carbon emissions, but also provide highly reliable communication.

[0004] The interaction of massive short-packet data is the core of communication in the Internet of Everything scenario. It is widely used in various military and civilian scenarios, mainly including the status update and location update of IoT devices, as well as various networked device operation-related command and control instructions and other applications. In such communication scenarios, the data packet length is the same as or even shorter than the pilot length, so its reliability and security transmission requirements are more stringent. For example, unreliable and unsafe short-packet communication may lead to equipment misoperation, damage to payload weapons or aircraft, etc. Summary of the invention

[0005] Purpose of the invention: In order to overcome the shortcomings of the background technology, the present invention discloses a short packet safe transmission method for a multi-intelligent reflective surface assisted energy collection system.

[0006] Technical solution: The short packet secure transmission method of the multi-intelligent reflector-assisted energy collection system disclosed in the present invention comprises a source node S, K intelligent reflectors IRS 1 ,…,IRS k , a relay node R without external energy supply, an eavesdropping node E and a destination node D, each smart reflection surface deploys N smart reflection units; with the assistance of the smart reflection surface and the relay node, the source node and the destination node communicate, and are eavesdropped by E at the same time;

[0007] The short packet secure transmission method comprises the following steps:

[0008] Step 1: One information transmission takes T time. During the time, S transmits an energy signal, which is reflected by K IRSs to R, and R collects energy from the received signal, where 0<τ<1 is the time conversion factor;

[0009] Step 2: In the next In the time period, S transmits a pilot signal with the assistance of K IRSs. R uses the least squares method to estimate the channel gain between it and S, and then feeds the estimation result back to S. S chooses Assist in the subsequent transmission of short packet data;

[0010] Step 3: In the next Within the time, S sends a signal through Reflection, R receives the signal y r , while E from S and The eavesdropping information, the received signals of E are recorded as y se and Among them, x 1 is the pilot signal, x 2 is the interference signal, P s is the total transmission power at S, α is the power allocation factor, 0<α<1; in the following In the time, using the energy collected in step 1, R receives the signal y r Amplify and forward to D;

[0011] Step 4: Calculate the received signal-to-noise ratio γ based on the received signal of D d , determine such that γ d >γ th The corresponding range of α, that is, α 1 <α<1, where γ th is a fixed threshold;

[0012] Step 5: In α 1 In the range of <α<1, find the lower bound R of the system’s confidentiality rate s Maximum power allocation factor α * ,Right now

[0013] Step 6: In the next Time, using the obtained optimal power allocation factor α * , in the selected With the assistance of and R, S sends a short packet data signal superimposed with an interference signal to D.

[0014] In step 1, the energy E collected at R r for:

[0015]

[0016] in, For S to IRS k The channel gain, For IRS k The channel gain to R, h sk The conjugate transpose of IRS k The phase shift matrix on k，i It's the IRS k The amplitude reflection coefficient of the i-th reflection unit; IRS k Can intelligently adjust the phase shift so that θ k，i =-arg(h sk，i g kr，i ), where θ k，i (0≤θ k，i ≤2π) is IRS k The phase shift of the i-th reflection unit, η (0<η<1) represents the energy conversion efficiency, represents an N×1 complex matrix;

[0017] Furthermore, in step 2, the selected intelligent reflective surface Satisfy the following formula:

[0018]

[0019] Furthermore, in step 3, R receives the signal y r for:

[0020]

[0021] in, For S to The channel gain, for The channel gain to R, for The conjugate transpose of express The phase shift matrix on yes The amplitude reflection coefficient of the i-th reflection unit on ; Can intelligently adjust the phase shift so that in yes The phase shift of the i-th reflection unit, n r The power at R is N 0Zero-mean additive white Gaussian noise;

[0022] R receives the signal y r After amplification, it is forwarded to D, and the signal received by D is y d for:

[0023] y d =Gh rd y r +n d , (4)

[0024] Among them, h rd is the channel gain of the R to D link, G is the amplification gain at R, n d The power at D is N 0 Zero-mean additive white Gaussian noise;

[0025] R amplifies the received information signal, and the amplification gain G is:

[0026]

[0027] in, is the transmission power at R;

[0028] E from S and eavesdropping information, and its received signal y se , They are:

[0029]

[0030]

[0031] Among them, h se is the channel gain of the S to E link, for Channel gain to E, n e and n 0 The power is N 0 Zero-mean additive white Gaussian noise.

[0032] Furthermore, in step 4, the received signal-to-noise ratio γ at D d for:

[0033]

[0034] in N 0 is the noise power;

[0035] Let γ d =γ th , we can solve α=α 1 ,in

[0036]

[0037] Furthermore, in step 5, the lower bound of the system's confidentiality rate is:

[0038]

[0039] Among them, γ d and γ e are the received signal-to-noise ratios at D and E, respectively, V d =1-(1+γ d ) -2 , V e =1-(1+γ e ) -2 , Q -1 (·) is the inverse function of the Gaussian Q function, M is the code length of the short packet, ∈ and δ are the decoding error probability and information leakage respectively;

[0040] In order to improve the probability of successful interception, E uses the maximum ratio combining method to process the received signal y se and Therefore, the received signal-to-noise ratio γ at E is e for:

[0041]

[0042] Beneficial effect: Compared with the prior art, the advantages of the present invention are: taking green communication as the research background, combining energy harvesting, multiple intelligent reflection surfaces and short packet communication confidential transmission rate, using channel gain to select the optimal intelligent reflection surface, and optimizing the power allocation factor through the signal-to-noise ratio and the lower bound of the confidentiality rate, and maximizing the lower bound of the short packet confidentiality transmission rate of the entire communication system under the premise of considering a certain reliability of communication, thereby ensuring the security of communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a model diagram of the transmission method of the present invention;

[0044] Figure 2 It is a time slot diagram of the transmission method of the present invention;

[0045] Figure 3 The present invention compares the outage probability results with the random selection scheme under different signal-to-noise ratios;

[0046] Figure 4 The present invention compares the lower bound results of the confidentiality rate with the random selection scheme under different signal-to-noise ratios;

[0047] Figure 5 The present invention shows the optimal distribution power factor results obtained under different signal-to-noise ratios. DETAILED DESCRIPTION

[0048] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0049] like Figure 1 As shown in the figure, the proposed system consists of a source node (S), K intelligent reflective surfaces (IRS 1 , ..., IRS K ), a relay node (R) without external energy supply, an eavesdropping node (E) and a destination node (D), each smart reflection surface is deployed with N smart reflection units; with the assistance of the smart reflection surface and R, the source node and the destination node communicate and are eavesdropped by E at the same time.

[0050] Step 1: One information transmission takes T time. During this time, S transmits an energy signal, which is reflected by K IRSs to R, which collects energy from the received signal.

[0051] In the formula, For S to IRS k The channel gain, For IRS k The channel gain to R, h sk The conjugate transpose of IRS k The phase shift matrix on k，i It's the IRS k The amplitude reflection coefficient of the i-th reflection unit; IRS k Can intelligently adjust the phase shift so that θ k，i =-arg(h sk，i g kr，i ), where θ k，i (0≤θ k，i ≤2π) is IRS k The phase shift of the i-th reflection unit, where 0<τ<1 is the time conversion factor, η(0<η<1) represents the energy conversion efficiency, Represents an N×1 complex matrix.

[0052] Step 2: In the next In the time period, S transmits a pilot signal with the assistance of K intelligent reflectors. R uses the least squares method to estimate the channel gain between it and S, and then feeds the estimation result back to S. S chooses Assist in subsequent short packet data transmission.

[0053] Selected smart reflective surface

[0054] Step 3: In the next Within the time, S sends a signal through Reflection, R receives the signal y r , while E from S and The eavesdropping information, the received signals of E are recorded as y se and Among them, x 1 is the pilot signal, x 2 is the interference signal, P s is the total transmission power at S, α is the power allocation factor (0<α<1); in the following In the time, using the energy collected in step 1, R receives the signal y r Amplify and forward to D;

[0055] Among them, R receives the signal For S to The channel gain, for The channel gain to R, for The conjugate transpose of express The phase shift matrix on yes The amplitude reflection coefficient of the i-th reflection unit; Can intelligently adjust the phase shift so that in yes The phase shift of the i-th reflection unit, n r The power at R is N 0 Zero-mean additive white Gaussian noise;

[0056] R receives the signal y r After amplification, it is forwarded to D, and the signal received by D is y d =Gh rd y r +n d , h rd is the channel gain of link R to D, G is the amplification gain at R, n d The power at D is N 0 Zero-mean additive white Gaussian noise;

[0057] Amplification gain at R Where P r is the transmit power at R, specifically:

[0058] E from and S eavesdrops on the information, which receives the signal y se They are: for The channel gain to E, h se is the channel gain from S to E, n e and n 0 The power is n 0 Zero-mean additive white Gaussian noise.

[0059] Step 4: Calculate the received signal-to-noise ratio γ based on the received signal of D d , determine such that γ d >γ th The corresponding range of α, that is, α 1 <α<1, where γ th is a fixed threshold.

[0060] Received signal-to-noise ratio at D in N 0 is the noise power;

[0061] Let γ d =γ th , we can solve α=α 1 ,in

[0062]

[0063] Step 5: In α 1 In the range of <α<1, find the lower bound R of the system’s confidentiality rate s Maximum power allocation factor α * ,Right now

[0064] The lower bound of the confidentiality rate of the short packet communication system is Where V d =1-(1+γ d ) -2 , V e =1-(1+γ e ) -2 , Q -1 (·) is the inverse function of the Gaussian Q function, M is the code length of the short packet, ∈ and δ are the decoding error probability and information leakage respectively;

[0065] In order to increase the probability of successful interception, the eavesdropper E uses the maximum ratio combining method to process the received signal y se and The received signal-to-noise ratio at E is

[0066] Step 6: In the next Time, using the obtained optimal power allocation factor α * , in the selected With the assistance of the relay node R, S sends a short packet data signal superimposed with an interference signal to D;

[0067] The following are the experimental results of the interruption probability, the lower bound of the confidentiality rate and the optimal power allocation factor of the present invention. The specific conditions of the simulation experiment are: independent and identically distributed Rayleigh fading channel, energy conversion rate η = 0.9, time slot factor τ = 0.6, noise power N 0 =1, the number of reflection units of the smart emitting surface is N=4, the amplitude reflection coefficient of each reflection unit of each smart reflection surface is β k，i =1(k=1,…,K,i=1,…,N), signal-to-noise ratio threshold value γ th =3, code length M = 200, decoding error probability ∈ = 10 -3 , information leakage δ = 10 -3 .

[0068] like Figure 1 As shown in the figure, the proposed system consists of a source node (S), K intelligent reflective surfaces (IRS 1 , ..., IRS K ), a relay node (R) without external energy supply, an eavesdropping node (E) and a destination node (D), each smart reflection surface is deployed with N smart reflection units; with the assistance of the smart reflection surface and R, the source node and the destination node communicate and are eavesdropped by E at the same time.

[0069] like Figure 2 As shown, one information transmission takes T time. In the time, where 0<τ<1 is the time conversion factor, S transmits the energy signal, which is reflected by K IRSs to R, and R collects energy from the received signal; Within a certain time, S transmits a pilot signal with the assistance of K smart reflectors. R estimates the channel gain between itself and S based on the received pilot signal, and then feeds the estimation result back to S. S selects the smart reflector accordingly. Assist in the subsequent short packet data transmission; in the next Within the time, S sends a signal through Reflection, R receives the signal y r , while E from S and The eavesdropping information, the received signals of E are recorded as y se and Among them, x 1 is the pilot signal, x 2 is the interference signal, Ps is the total transmission power at S, α is the power allocation factor (0<α<1); Within this time, using the energy collected previously, R receives the signal y r Amplify and forward to D; calculate the received signal-to-noise ratio γ based on the received signal of D d , determine such that γ d >γ th The corresponding range of α, that is, α 1 <α<1, where γ th is a fixed threshold; 1 <α<1, then select the lower bound R of the system's confidentiality rate s Maximum power allocation factor α * ; in the last Time, using the power allocation factor α obtained * , on the selected smart reflective surface With the assistance of the relay node R, S sends a short packet data signal superimposed with an interference signal to communicate with D.

[0070] Under different numbers of smart reflectors (K) and different signal-to-noise ratios (SNR), Figure 3 , Figure 4 The results of the present invention and the random selection scheme in terms of interruption probability and lower bound of confidentiality rate are compared. Figure 5 The optimal power allocation factor result under the scheme of the present invention is given. Figure 3-Figure 5 The horizontal axis is the signal-to-noise ratio (SNR, in dB), and the vertical axis is the interruption probability, the lower bound of the confidentiality rate, and the optimal power allocation factor. In the figure, "—" is the case of K=5, "---" is the case of K=4, the symbol "+" is the solution of the present invention, and the symbol "*" is the random selection solution.

[0071] from Figure 3 , Figure 4 It can be seen that: under any K value and any signal-to-noise ratio SNR value, the interruption probability of the present invention is significantly lower than that of the random selection scheme, and the lower bound of the confidentiality rate is significantly higher than that of the random selection scheme. In addition, it can be found that: as the K value increases, the interruption probability of the method of the present invention decreases and the confidentiality rate increases. For example, when K=5, SNR=2dB, the interruption probability of the present invention is about 0.276, and the lower bound of the confidentiality rate is about 2.026; the interruption probability under the random selection method is 0.769, and the lower bound of the confidentiality rate is about 0.495. This shows that the interruption probability and the lower bound of the confidentiality rate of the present invention are significantly better than the random selection scheme.

Claims

1. A short packet secure transmission method for a multi-intelligent reflector-assisted energy collection system, characterized in that: The system includes a source node S, K intelligent reflectors IRS1,…,IRS k , a relay node R without external energy supply, an eavesdropping node E and a destination node D, each smart reflection surface deploys N smart reflection units; with the assistance of the smart reflection surface and the relay node, the source node and the destination node communicate, and are eavesdropped by E at the same time; The short packet secure transmission method comprises the following steps: Step 1: One information transmission takes T time. During the time, S transmits an energy signal, which is reflected by K IRSs to R, and R collects energy from the received signal, where 0<τ<1 is the time conversion factor; Step 2: In the next In the time period, S transmits a pilot signal with the assistance of K IRSs. R uses the least squares method to estimate the channel gain between it and S, and then feeds the estimation result back to S. S chooses Assist in the subsequent transmission of short packet data; Step 3: In the next Within the time, S sends a signal through Reflection, R receives the signal y r , while E from S and The eavesdropping information, the received signals of E are recorded as y se and k*e , where x1 is the pilot signal, x2 is the interference signal, P s is the total transmission power at S, α is the power allocation factor, 0<α<1; in the following In the time, using the energy collected in step 1, R receives the signal y r Amplify and forward to D; Step 4: Calculate the received signal-to-noise ratio γ based on the received signal of D d , determine such that γ d >γ th The corresponding range of α is α1<α<1, where γ th is a fixed threshold; Step 5: In the range of α1<α<1, find the lower bound R of the system's confidentiality rate s Maximum power allocation factor α * ,Right now Step 6: In the next Time, using the obtained optimal power allocation factor α * , in the selected With the assistance of and R, S sends a short packet data signal superimposed with an interference signal to D; In step 1, the energy E collected at R r for: in, For S to IRS k The channel gain, For IRS k The channel gain to R, h sk The conjugate transpose of IRS k The phase shift matrix on k，i It's the IRS k The amplitude reflection coefficient of the i-th reflection unit; IRS k Can intelligently adjust the phase shift so that θ k，i =-arg(h sk，i g kr，i ), where θ k，i (0≤θ k，i ≤2π) is IRS k The phase shift of the i-th reflection unit, η (0<η<1) represents the energy conversion efficiency, represents an N×1 complex matrix; In step 2, the selected smart reflective surface Satisfy the following formula: In step 3, R receives the signal y r for: in, For S to The channel gain, for The channel gain to R, for The conjugate transpose of express The phase shift matrix on yes The amplitude reflection coefficient of the i-th reflection unit on ; Can intelligently adjust the phase shift so that in yes The phase shift of the i-th reflection unit, n r is zero-mean additive white Gaussian noise with power N0 at R; R receives the signal y r After amplification, it is forwarded to D, and the signal received by D is y d for: y d =Gh rd y r +n d , ⑷ Among them, h rd is the channel gain of the R to D link, G is the amplification gain at R, n d is zero-mean additive white Gaussian noise with power N0 at D; R amplifies the received information signal, and the amplification gain G is: in, is the transmission power at R; E from S and eavesdropping information, and its received signal y se , They are: Among them, h se is the channel gain of the S to E link, for Channel gain to E, n e and n0 are both zero-mean additive white Gaussian noises with power N0.

2. The short packet secure transmission method of the multi-intelligent reflector-assisted energy collection system according to claim 1 is characterized in that: In step 4, the received signal-to-noise ratio γ at D d for: in N0 is the noise power; Let γ d =γ th , we can solve α=α1, where 3. The short packet secure transmission method of the multi-intelligent reflector-assisted energy collection system according to claim 2 is characterized in that: In step 5, the lower bound of the system's confidentiality rate is: Among them, γ d and γ e are the received signal-to-noise ratios at D and E, respectively, V d =1-(1+γ d ) -2 , V e =1-(1-γ e ) -2 , Q -1 (·) is the inverse function of the Gaussian Q function, M is the code length of the short packet, ∈ and δ are the decoding error probability and information leakage respectively; In order to improve the probability of successful interception, E uses the maximum ratio combining method to process the received signal y se and Therefore, the received signal-to-noise ratio γ at E is e for:

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