A secure transmission method for indoor hybrid PLC / VLC network

Abstract

The application discloses a kind of safety transmission methods of indoor mixed PLC / VLC network, information from signal source S is transmitted to relay node by power line link, and is transmitted to the legal user randomly moving on the ground by visible light link after decoding and forwarding;Due to the broadcast characteristics of visible light, the eavesdropper in the coverage of visible light will also receive the information, therefore, the present method suppresses the reception of eavesdropper by setting the protection zone, and obtains the security outage probability and the secret throughput of indoor mixed PLC / VLC network under the random waypoint movement model of legal user based on the analysis of the channel statistical characteristics of power line link and visible light link;Simulation verifies that the performance of the safety transmission method disclosed in the application is related to the occurrence probability of impulse noise in power line link, the power ratio of impulse noise and background noise, the half-power emitting half-angle of LED in visible light link, the radius of protection zone and other parameters.

Description

A secure transmission method for indoor hybrid PLC / VLC networks Technical Field

[0001] This invention relates to the fields of power line communication and visible light communication technologies, and specifically to a secure transmission method for indoor hybrid PLC / VLC networks. Background Technology

[0002] With the rapid development of wireless communication technology, mobile devices and applications require higher speeds and greater capacity connections. However, traditional wireless communication technologies, primarily based on radio frequency (RF), face increasing bandwidth demands due to spectrum limitations. As one of the potential key technologies for 6G mobile communication, visible light communication (VLC) has gradually developed into a mature wireless access solution due to its advantages such as high transmission power, no electromagnetic interference, and no need for spectrum certification, which can alleviate the bandwidth pressure on RF communication. VLC not only utilizes light-emitting diodes (LEDs) to simultaneously achieve lighting and communication functions but also meets the requirements of green wireless communication, attracting significant attention from researchers. However, LEDs generally cannot be used directly as information sources; they must be connected to the backbone network to avoid becoming information silos.

[0003] An effective approach to addressing this challenge is to use power line communication (PLC) links as the backhaul network for VLC links. PLCs are a promising communication medium that can leverage existing power line infrastructure for data communication and power transmission in indoor and outdoor environments (power systems, buildings, vehicles, etc.). Especially in environments where wireless signals suffer loss and attenuation, PLCs can assist wireless communication in better completing data transmission tasks. Furthermore, PLCs are a key technology in smart grids, the Internet of Things (IoT), and other fields. More importantly, the cables of a PLC system can be naturally connected to LEDs in a VLC network, providing them with information and power. Therefore, hybrid PLC / VLC networks outperform standalone PLC and VLC networks in many aspects, including high-speed transmission, ease of access, wide coverage, and low-cost deployment, making them of significant research value.

[0004] On the other hand, in indoor hybrid PLC / VLC networks, VLC's open broadcast nature poses challenges to secure information transmission, including issues like information leakage and interception. Traditional methods of enhancing communication security through encryption are computationally complex; however, the emerging physical layer security technology can directly guarantee secure and reliable information transmission at the physical layer with lower computational complexity. Based on information theory, physical layer security leverages the differences in wireless channels to provide security for communication networks. This technology not only provides the first line of defense against eavesdropping attacks in practical applications but also effectively complements traditional encryption techniques. Current research on physical layer security primarily focuses on standalone PLC and standalone VLC networks; research on physical layer security for indoor hybrid PLC / VLC networks is still limited. Therefore, researching secure transmission methods for indoor hybrid PLC / VLC networks is of significant importance. Summary of the Invention

[0005] The purpose of this invention is to provide a secure transmission method for indoor hybrid PLC / VLC networks, addressing the physical layer security issues in such networks.

[0006] The technical solution to achieve the objective of this invention is:

[0007] A secure transmission method for indoor hybrid PLC / VLC networks includes the following steps:

[0008] 1) In an indoor hybrid power line communication (PLC) / visible light communication (VLC) network, the power line communication link serves as the backhaul network for the visible light communication link, providing power and information. Information from the source S is transmitted via the power line link to the relay node Relay. After decoding and forwarding, the Relay sends the information to legitimate users randomly moving on the ground via the visible light link. Due to the broadcast characteristics of visible light, eavesdroppers within the visible light coverage area will also receive the message. Therefore, protection zones are set up to suppress the reception of eavesdroppers.

[0009] 2) Secure transmission in an indoor hybrid PLC / VLC network is achieved through two-hop communication. The specific process is as follows:

[0010] 2-1) In the first hop, the source S transmits the electrical signal to the relay node Relay via the power line link; the channel gain of the power line link follows a log-normal distribution, and the additional noise of the power line link includes background noise and impulse noise, which are modeled by a Poisson-Gaussian mixture statistical model; based on the analysis of the channel characteristics of the power line link, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio of this link are obtained.

[0011] 2-2) In the second hop, Relay applies a decoding and forwarding protocol and sends the electro-optically converted optical signal to the legitimate user on the ground via LEDs, which follows the random waypoint (RWP) mobility model distribution. To suppress eavesdroppers from receiving legitimate messages, a protected area is set up to prevent them from getting infinitely close to the legitimate user. Based on the channel characteristics of visible light communication, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio between the legitimate user and the eavesdropper in the visible light link are obtained.

[0012] 3) Based on the statistical distribution of the instantaneous signal-to-noise ratio of the power line link obtained in step 2-1) and the statistical distribution of the instantaneous signal-to-noise ratio of the legitimate user and the eavesdropper in the visible light link obtained in step 2-2), the security interruption probability and confidential throughput of the indoor hybrid PLC / VLC network are further obtained.

[0013] In step 1), the signal source S is located outdoors and is connected to the relay node Relay at the top of the building indoors via a power line link. The relay node Relay is configured with an electro-optical converter and an LED transmitter; the maximum coverage radius of the LED's optical beam is R. c The radius of the protected area is R0; legitimate user B is within a radius of R0. c The circle contains an RWP distribution, and its horizontal distance from the center O is r. B The eavesdropper E is in the annular region, i.e., the region with an outer radius of R. c The inner radius is R0 and the distribution within it is uniform, with a horizontal distance r from the center O. E Both B and E are equipped with a single photodetector (PD) receiver.

[0014] In step 2-1), the source S transmits the electrical signal x to the relay node Relay, and then the Relay receives the signal y. R Represented as:

[0015]

[0016] In the above formula (1), the subscript SR represents the power line link between the source S and the relay node Relay; θ=ε0+ε1f u For the attenuation of the PLC link, ε0 and ε1 are constants, f is the operating frequency, u is the exponential attenuation factor, and L SR P represents the distance from the source S to the relay node Relay; S1 h is the transmission power of the signal source S; SR n is the channel gain of the power line link. SR Additional noise to power line links;

[0017] Channel gain h of power line link SR Its probability density function is:

[0018]

[0019] Formula (2) above is for a random variable h SR The log-normal distribution, μ SR and It is lnh SR The mean and variance;

[0020] Random switching of access devices and various low-power components in power line links generates additional noise, including background noise and impulse noise. Modeled using a Poisson-Gaussian mixture statistical model, the additional noise n... SR Represented as:

[0021] n SR =n Q +n I (3)

[0022] Where, n Q For background noise, n I =n T n in It is impulse noise; n T The transient impulse noise in the PLC link is represented by a discrete Poisson random process; n in and n Q The model is based on Gaussian white noise with a mean of 0 and a variance of . and In the above formula (3), it is assumed that n T and n Q n in independent;

[0023] Additional noise n in power line links SR The probability density function is:

[0024]

[0025] Where P = βT a T represents the probability of impulse noise arriving in the channel, β represents the arrival rate, and T represents the probability of impulse noise arriving in the channel. a It is the duration of the impulse noise; It is the power ratio of impulse noise to background noise;

[0026] Instantaneous signal-to-noise ratio γ of the power line link from source S to relay node Relay SR Represented as:

[0027]

[0028] in, It is the average signal-to-noise ratio of the power line link when only background noise exists in the additional noise; It is the average signal-to-noise ratio of a power line link when both background noise and impulse noise are present in the additional noise; γ SR-1 It is the instantaneous signal-to-noise ratio of a power line link when only background noise exists in the additional noise; γ SR-2 It is the instantaneous signal-to-noise ratio of a power line link when both background noise and impulse noise are present in the additional noise.

[0029] When the additional noise in the power line link consists only of background noise, γ can be obtained using formulas (2) and (5). SR-1 The probability density function is:

[0030]

[0031] in, σ a =2σ SR ;

[0032] When the additional noise in the power line link includes both background noise and impulse noise, γ can be obtained using formulas (2) and (5). SR-2 The probability density function is:

[0033]

[0034] in, σ b =2σ SR ;

[0035] Combining formula (4), and integrating formulas (6) and (7), we obtain γ. SR The probability density function is:

[0036]

[0037] Integrating equation (8), we obtain γ. SR The cumulative distribution function is:

[0038]

[0039] in, Represents the complementary error function;

[0040] In step 2-2), user k, k∈{B, E}, uses its own equipped PD receiver to receive the signal decoded and forwarded from the relay node Relay. Then the received signal at k is:

[0041]

[0042] in, This is the signal after Relay decoding and forwarding; n Rk The visible light link contains additive white Gaussian noise with a mean of 0 and a variance of N0; h R,k Let be the channel gain of the visible light link from Relay to user k;

[0043] The channel gain h of the visible light link from Relay to user k R,k Represented as:

[0044]

[0045] Where, α k ∈[0,φ 1 / 2 ] is the LED radiation angle, φ 1 / 2 The half-power emission angle of the LED; ρ=-ln2 / ln(cos(φ) 1 / 2 )) represents the Lambertian radiation order of the LED; ψ k The incident angle of the PD receiver. T represents the field of view of the PD receiver; f (ψ k ) represents the gain of the optical filter; g f (ψ k () represents the gain of the optical concentrator. n d R is the reflection coefficient; H is the vertical distance between the plane where the LED is located and the plane where user k is located; r k Let α be the horizontal distance between the LED's projection point on the ground and the user k; M and χ are the effective physical detection area and detection sensitivity of the PD receiver, respectively. Assume α... k =ψ k ,but

[0046] make The squared channel gain of the visible light link is:

[0047]

[0048] Instantaneous signal-to-noise ratio γ of user k in a visible light link R,k for:

[0049]

[0050] in, The signal-to-noise ratio of the visible light link is represented by A, where A is the photoelectric conversion coefficient and P is the signal-to-noise ratio of the visible light link. R The transmitted light power of the LEDs embedded in the relay;

[0051] Since legitimate user B is in a radius of R c The circle follows an RWP distribution, and the horizontal distance r from B to the center O is... B The probability density function is When considering a two-dimensional topology, take j = 3, δ i =[1,3,5],△ i = [324, -420, 96] / 73, then r B The probability density function is expressed as:

[0052]

[0053] Using formulas (12), (13), and (14) and combining them with the variable substitution method, the instantaneous signal-to-noise ratio γ of legitimate user B is obtained. R,B The probability density function is:

[0054]

[0055] in,

[0056] Integrating equation (15) yields the instantaneous signal-to-noise ratio γ of legitimate user B. R,B The cumulative distribution function is:

[0057]

[0058] in,

[0059] Since the eavesdropper E is in the annular region, i.e., the outer radius is R... c The inner radius is R0 and follows a uniform distribution. The horizontal distance from E to the center O is r. E The probability density function can be expressed as: R0≤x≤R c By combining formulas (12) and (13), the instantaneous signal-to-noise ratio γ of the eavesdropper E is obtained. R,E The probability density function is:

[0060]

[0061] Integrating equation (17) yields the instantaneous signal-to-noise ratio γ of the eavesdropper E. R,E The cumulative distribution function is:

[0062]

[0063] Where, γ R,E ∈[I min ,I max ],

[0064] In step 3), the calculation process for the security interruption probability and confidentiality throughput of the hybrid PLC / VLC network is as follows:

[0065] In the first hop, the instantaneous safety capacity C1 of the power line link is:

[0066]

[0067] In the second hop, the eavesdropper E tries to eavesdrop on the private information transmitted to the legitimate user B from the relay node Relay. Therefore, the instantaneous security capacity C2 of the visible light link is:

[0068]

[0069] Where, {x} + =max{x,0}, where max{·} is the maximum value operation;

[0070] Because the relay node uses a decoding and forwarding protocol, the security capacity C of the indoor hybrid PLC / VLC network is... S For: C S =min{C1,C2}, min{·} is the minimum value operation;

[0071] The security interruption probability mentioned in 3-1) is defined as the security capacity C of the hybrid system. S The probability that the value is less than the set target confidentiality threshold is expressed as:

[0072]

[0073] Among them, P SOP R represents the probability of a safety interruption; Pr{·} represents the probability calculation; R th The target confidentiality threshold is set;

[0074] Then, substituting formulas (8) and (9) from step 2-1) and formulas (15), (16), (17) and (18) from step 2-2) into formula (21), the safety interruption probability P of the indoor hybrid PLC / VLC network is obtained. SOP for:

[0075]

[0076] in,

[0077]

[0078] The confidential throughput mentioned in 3-2) is defined as the product of the target confidentiality threshold and the probability of secure and reliable transmission of the system, expressed as:

[0079] ST=R th ×(1-P SOP ) (twenty three)

[0080] Where ST represents the confidential throughput;

[0081] Substituting formula (22) into (23), the secure throughput ST of the indoor hybrid PLC / VLC network is obtained as follows:

[0082]

[0083] Beneficial effects: The present invention provides a secure transmission method for indoor hybrid PLC / VLC networks, which has the following advantages:

[0084] 1. The performance of the secure transmission method proposed in this invention is related to parameters such as the probability of impulse noise occurrence in the power line link, the power ratio of impulse noise to background noise, the half-power emission angle of LEDs in the visible light link, and the radius of the protection zone. Therefore, this method can be used to design and optimize the parameters of indoor power line / visible light hybrid networks to improve the network's security performance.

[0085] 2. To provide a theoretical basis for enhancing the physical layer security of indoor hybrid PLC / VLC networks;

[0086] 3. Promote the application of physical layer security technology for indoor hybrid PLC / VLC networks in scenarios such as hospitals, aircraft cabins, and underground mines, while also advancing its practical application in fields such as smart grids and the Internet of Things. Attached Figure Description

[0087] Figure 1 is a schematic diagram of an indoor hybrid PLC / VLC network;

[0088] Figure 2 illustrates the impact of whether a protected area is set up and the change in the target confidentiality threshold on the probability of hybrid network security outage.

[0089] Figure 3 is a schematic diagram illustrating the impact of changes in the vertical distance between the LED and the user on the probability of network outage in hybrid networks.

[0090] Figure 4 is a schematic diagram illustrating the impact of the probability change of power line link impulse noise on the probability of hybrid network security outage;

[0091] Figure 5 is a schematic diagram illustrating the impact of the half-power emission half-angle variation of LEDs on the probability performance of hybrid network security outages.

[0092] Figure 6 is a schematic diagram illustrating the impact of changes in the radius of the protected area on the confidential throughput performance of the hybrid network. Detailed Implementation

[0093] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this is not intended to limit the scope of the invention.

[0094] Example:

[0095] A secure transmission method for indoor hybrid PLC / VLC networks includes the following steps:

[0096] 1) As shown in Figure 1, in an indoor hybrid power line communication (PLC) / visible light communication (VLC) network, the power line communication link serves as the backhaul network for the visible light communication link, providing power and information. Information from the source S is transmitted via the power line link to the relay node Relay. After decoding and forwarding, Relay transmits the information via the visible light link to legitimate users randomly moving on the ground. Due to the broadcast characteristics of visible light, eavesdroppers within the visible light coverage area will also receive the message. Protection zones are set up to suppress eavesdropping. The source S is located outdoors and is connected to the relay node Relay at the top of the building via a power line link. The relay node Relay is configured with an electro-optical converter and an LED transmitter; the maximum coverage radius of the LED's light beam is R. c The radius of the protected area is R0; legitimate user B is within a radius of R0. c The circle contains an RWP distribution, and its horizontal distance from the center O is r. B The eavesdropper E is in the annular region, i.e., the region with an outer radius of R. c The inner radius is R0 and the distribution within it is uniform, with a horizontal distance r from the center O. E Both B and E are equipped with a single photodetector (PD) receiver.

[0097] 2) Secure transmission in an indoor hybrid PLC / VLC network is achieved through two-hop communication. The specific process is as follows:

[0098] 2-1) In the first hop, the source S transmits the electrical signal to the relay node Relay via the power line link; the channel gain of the power line link follows a log-normal distribution, and the additional noise of the power line link includes background noise and impulse noise, which are modeled by a Poisson-Gaussian mixture statistical model; based on the analysis of the channel characteristics of the power line link, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio of this link are obtained.

[0099] The source S transmits electrical signal x to the relay node Relay, then the Relay receives signal y. R Represented as:

[0100]

[0101] In the above formula (1), the subscript SR represents the power line link between the source S and the relay node Relay; θ=ε0+ε1f u For the attenuation of the PLC link, ε0 and ε1 are constants, f is the operating frequency, u is the exponential attenuation factor, and L SR P represents the distance from the source S to the relay node Relay; S1 h is the transmission power of the signal source S; SR n is the channel gain of the power line link. SR Additional noise to power line links;

[0102] Channel gain h of power line link SR Its probability density function is:

[0103]

[0104] Formula (2) above is for a random variable h SR The log-normal distribution, μ SR and It is lnh SR The mean and variance;

[0105] Random switching of access devices and various low-power components in power line links generates additional noise, including background noise and impulse noise. This can be modeled using a Poisson-Gaussian mixture statistical model, where the additional noise n... SR Represented as:

[0106]

[0107] Where, n Q For background noise, n I =n T n in It is impulse noise; n T The transient impulse noise in the PLC link is represented by a discrete Poisson random process; n in and n Q The model is based on Gaussian white noise with a mean of 0 and a variance of . and In the above formula (3), it is assumed that n T and n Qn in independent;

[0108] Additional noise n in power line links SR The probability density function is:

[0109]

[0110] Where P = βT a T represents the probability of impulse noise arriving in the channel, β represents the arrival rate, and T represents the probability of impulse noise arriving in the channel. a It is the duration of the impulse noise; It is the power ratio of impulse noise to background noise;

[0111] Instantaneous signal-to-noise ratio γ of the power line link from source S to relay node Relay SR Represented as:

[0112]

[0113] in, It is the average signal-to-noise ratio of the power line link when only background noise exists in the additional noise; It is the average signal-to-noise ratio of a power line link when both background noise and impulse noise are present in the additional noise; γ SR-1 It is the instantaneous signal-to-noise ratio of a power line link when only background noise exists in the additional noise; γ SR-2 It is the instantaneous signal-to-noise ratio of a power line link when both background noise and impulse noise are present in the additional noise.

[0114] When the additional noise in the power line link consists only of background noise, γ can be obtained using formulas (2) and (5). SR-1 The probability density function is:

[0115]

[0116] When the additional noise in the power line link includes both background noise and impulse noise, γ can be obtained using formulas (2) and (5). SR-2 The probability density function is:

[0117]

[0118] in, σ a =σ b =2σ SR ;

[0119] Combining formula (4), and integrating formulas (6) and (7), we obtain γ.SR The probability density function is:

[0120]

[0121] Integrating equation (8), we obtain γ. SR The cumulative distribution function is:

[0122]

[0123] in, Represents the complementary error function;

[0124] 2-2) In the second hop, Relay applies a decoding and forwarding protocol and sends the electro-optically converted optical signal to the legitimate user on the ground via LEDs, which follows the random waypoint (RWP) mobility model distribution. To suppress eavesdroppers from receiving legitimate messages, a protected area is set up to prevent them from getting infinitely close to the legitimate user. Based on the channel characteristics of visible light communication, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio between the legitimate user and the eavesdropper in the visible light link are obtained.

[0125] User k, k∈{B, E}, uses its own equipped PD receiver to receive data from relay node Rela. y After decoding and forwarding the signal, the received signal at point k is:

[0126]

[0127] in, This is the signal after Relay decoding and forwarding; n R,k The visible light link contains additive white Gaussian noise with a mean of 0 and a variance of N0; h R,k Let be the channel gain of the visible light link from Relay to user k;

[0128] The channel gain h of the visible light link from Relay to user k R,k Represented as:

[0129]

[0130] Where, α k ∈[0,φ 1 / 2 ] is the LED radiation angle, φ 1 / 2 The half-power emission angle of the LED; ρ=-ln2 / ln(cos(φ) 1 / 2 )) represents the Lambertian radiation order of the LED; ψ k The incident angle of the PD receiver. T represents the field of view of the PD receiver; f (ψ k ) represents the gain of the optical filter; g f (ψ k () represents the gain of the optical concentrator. n d R is the reflection coefficient; H is the vertical distance between the plane where the LED is located and the plane where user k is located; r k Let α be the horizontal distance between the LED's projection point on the ground and the user k; M and χ are the effective physical detection area and detection sensitivity of the PD receiver, respectively. It is usually assumed that α... k =ψ k ,but

[0131]

[0132] make The squared channel gain of the visible light link is:

[0133]

[0134] Instantaneous signal-to-noise ratio γ of user k in a visible light link R,k for:

[0135]

[0136] in, The signal-to-noise ratio of the visible light link is represented by A, where A is the photoelectric conversion coefficient and P is the signal-to-noise ratio of the visible light link. R The transmitted light power of the LEDs embedded in the relay;

[0137] Since legitimate user B is in a radius of R c The circle follows an RWP distribution, and the horizontal distance r from B to the center O is... B The probability density function is 0≤x≤R max When considering two-dimensional topology, take j=3, δ i =[1,3,5],△ i = [324, -420, 96] / 73, then r B The probability density function is expressed as:

[0138]

[0139] Using formulas (12), (13), and (14) and combining them with the variable substitution method, the instantaneous signal-to-noise ratio γ of legitimate user B is obtained. R,B The probability density function is:

[0140]

[0141] in,

[0142] Integrating equation (15) yields the instantaneous signal-to-noise ratio γ of legitimate user B. R,B The cumulative distribution function is:

[0143]

[0144] in,

[0145] Since the eavesdropper E is in the annular region, i.e., the outer radius is R... c The inner radius is R0 and follows a uniform distribution. The horizontal distance from E to the center O is r. E The probability density function can be expressed as: R0≤x≤R c By combining formulas (12) and (13), the instantaneous signal-to-noise ratio γ of the eavesdropper E is obtained. R,E The probability density function is:

[0146]

[0147] Integrating equation (17) yields the instantaneous signal-to-noise ratio γ of the eavesdropper E. R,E The cumulative distribution function is:

[0148]

[0149] in,

[0150] 3) Based on the statistical distribution of the instantaneous signal-to-noise ratio of the power line link obtained in step 2-1) and the statistical distribution of the instantaneous signal-to-noise ratio of the legitimate user B and the eavesdropper E in the visible light link obtained in step 2-2), calculate the security interruption probability and confidentiality throughput of the indoor hybrid PLC / VLC network, as shown below:

[0151] In the first hop, the instantaneous safety capacity C1 of the power line link is:

[0152]

[0153] In the second hop, the eavesdropper E tries to eavesdrop on the private information transmitted to the legitimate user B from the relay node Relay. Therefore, the instantaneous security capacity C2 of the visible light link is:

[0154]

[0155] Where, {x} + =max{x,0}, where max{·} is the maximum value operation;

[0156] Because the relay node uses a decoding and forwarding protocol, the security capacity C of the indoor hybrid PLC / VLC network is... S For: C S =min{C1,C2}, min{·} is the minimum value operation;

[0157] The security interruption probability mentioned in 3-1) is defined as the security capacity C of the hybrid system. S The probability that the value is less than the set target confidentiality threshold is expressed as:

[0158] P SOP =Pr{C S <R th}

[0159] =1-Pr{C1≥R th}Pr{C2≥R th} (twenty one)

[0160] Where P SOP R represents the probability of a safety interruption; Pr{·} represents the probability calculation; R th The target confidentiality threshold is set;

[0161] Substituting formulas (8) and (9) from step 2-1) and formulas (15), (16), (17) and (18) from step 2-2) into formula (21), the safety interruption probability P of the indoor hybrid PLC / VLC network is obtained. SOP for:

[0162]

[0163] in,

[0164]

[0165] The confidential throughput mentioned in 3-2) is defined as the product of the target confidentiality threshold and the probability of secure and reliable transmission of the system, expressed as:

[0166] ST=R th ×(1-P SOP ) (twenty three)

[0167] Where ST represents the confidential throughput;

[0168] Substituting formula (22) into (23), the secure throughput ST of the indoor hybrid PLC / VLC network is obtained as follows:

[0169]

[0170] The following measures were taken to verify the beneficial effects of the present invention:

[0171] Figure 2 shows whether the protected area radius R0 and the target confidentiality threshold R are set. th The impact of changes on the security outage probability of indoor hybrid PLC / VLC networks. As shown in Figure 2, setting a protected area can improve the security outage probability performance of the hybrid network. This is because eavesdroppers can only move randomly within the visible light area outside the protected area and cannot infinitely approach legitimate users, thus increasing the Euclidean distance between the eavesdropper and the LED, thereby reducing the signal-to-noise ratio of the eavesdropper E. When the radius of the protected area is fixed, increasing the target security threshold R... th This will lead to a decrease in the security performance of the hybrid system. As can be seen from Figure 2, as the half-power emission angle of the LED increases, the security interruption probability performance of the hybrid system deteriorates. This is because the larger the half-power emission angle of the LED, the more diffuse its transmitted beam becomes, making it easier for the private information transmitted to the legitimate user B to be leaked to the eavesdropper E, ultimately leading to a decrease in the security performance of the hybrid system.

[0172] Figure 3 illustrates the impact of variations in the vertical distance H between the LED and the user on the security outage probability of the hybrid network. As shown in Figure 3, increasing H reduces the security performance of the hybrid system. This is because a larger H increases the Euclidean distance between the LED and the legitimate user B, weakening the received signal strength of B and thus reducing the security performance of the hybrid system. Figure 3 also shows that reducing the power ratio η of impulse noise to background noise in the power line link can improve the security outage probability performance of the hybrid network. This is because a smaller η indicates a smaller proportion of impulse noise in the power line link, making communication in the hybrid system less susceptible to interruption. Furthermore, the system's security performance increases with the average signal-to-noise ratio of the power line link. The increase was improved.

[0173] Figure 4 illustrates the impact of changes in the probability P of impulse noise occurrence in power line links on the security outage probability of hybrid networks. As shown in Figure 4, increasing the probability P of impulse noise occurrence in power line links reduces the security outage probability performance of hybrid networks. This is because impulse noise in power line links mainly originates from the random switching of various low-power components connected to the cable. The larger P is, the higher the probability of impulse noise occurrence in the hybrid system, making communication more susceptible to interruption and thus deteriorating the security outage probability performance of the hybrid system. Similarly, increasing the average signal-to-noise ratio of the power line link... It can improve the system's security performance.

[0174] Figure 5 shows the half-power emission angle φ of an LED. 1 / 2 The impact of changes on the probability of network outages in hybrid networks. As shown in Figure 5, at the target confidentiality threshold R... th The value is 0.6 bits / second / hertz, increasing the LED half-power emission angle φ. 1 / 2 The security outage probability performance of hybrid networks is reduced because increasing φ 1 / 2 This means that the LED beamwidth increases, thereby increasing the signal-to-noise ratio received by the eavesdropper E. Furthermore, R... th The smaller the value, the better the safety interruption performance of the hybrid system.

[0175] Figure 6 shows the impact of variations in the radius R0 of different protected areas on the secure throughput of the hybrid system. As shown in Figure 6, the system's secure throughput reaches the target security threshold of R0. th The value gradually increases within the range of [0, 1.4] bits / second / hertz, when the target confidentiality threshold is within R... th Within the range of [1.4, 2.6] bits / second / hertz, the system's secure throughput gradually decreases. This is because, when the target secrecy threshold is small, the increase in the secure throughput of the hybrid system depends on R. th Then, at the inflection point, with R... th As the protection zone radius increases, the probability of security outages decreases significantly, leading to a corresponding decrease in the confidential throughput of the hybrid system. As shown in Figure 6, increasing the protection zone radius can further improve the security performance of the hybrid system.

Claims

1. A secure transmission method for indoor hybrid PLC / VLC networks, characterized in that, The process includes the following steps: 1) In an indoor hybrid power line communication PLC / visible light communication VLC network, the power line communication link serves as the backhaul network for the visible light communication link, providing power and information. Information from source S is transmitted via the power line link to the relay node Relay. After decoding and forwarding, Relay sends the information via the visible light link to legitimate users randomly moving on the ground. Due to the broadcast characteristics of visible light, eavesdroppers within the visible light coverage area will also receive the information. Therefore, a protected area is set up to suppress the reception of eavesdroppers. 2) Secure transmission in the indoor hybrid PLC / VLC network is achieved through two-hop communication. The specific process is as follows: 2-1) In the first hop, source S transmits electrical signals via the power line link to the relay node R. elay; where the channel gain of the power line link follows a log-normal distribution, and the additional noise of the power line link includes background noise and impulse noise, which is modeled by a Poisson-Gaussian mixture statistical model; based on the analysis of the channel characteristics of the power line link, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio of this link are obtained; 2-2) In the second hop, Relay applies a decoding and forwarding protocol and sends the electro-optically converted optical signal through a light-emitting diode (LED) to the legitimate user on the ground that follows the random waypoint (RWP) movement model distribution. To suppress eavesdroppers from receiving legitimate messages, a protected area is set up to prevent them from getting infinitely close to the legitimate user; based on the channel characteristics of visible light communication, the instantaneous signal-to-noise ratio of the legitimate user and the eavesdropper in the visible light link is obtained. 2) Secure transmission of indoor hybrid PLC / VLC networks is achieved through two-hop communication. The specific process is as follows: 2-1) In the first hop, the source S transmits the electrical signal to the relay node Relay via the power line link; the channel gain of the power line link follows a log-normal distribution, and the additional noise of the power line link includes background noise and impulse noise, which are modeled using a Poisson-Gaussian mixture statistical model; based on the analysis of the channel characteristics of the power line link, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio of this link are obtained; 2-2) In the second hop, Relay applies a decoding and forwarding protocol and sends the electro-optically converted optical signal to the ground via a light-emitting diode (LED) following a random waypoint RW. For legitimate users in the P-mobility model distribution, to suppress eavesdroppers from receiving legitimate messages, a protected area is set up to prevent them from getting infinitely close to the legitimate users; based on the channel characteristics of visible light communication, the probability density function and cumulative distribution function of the instantaneous signal-to-noise ratio of legitimate users and eavesdroppers in the visible light link are obtained; 3) Based on the statistical distribution of the instantaneous signal-to-noise ratio of the power line link obtained in step 2-1) and the statistical distribution of the instantaneous signal-to-noise ratio of the visible light link between legitimate users and eavesdroppers obtained in step 2-2), the security interruption probability and confidential throughput of the indoor hybrid PLC / VLC network are further obtained; In step 1), the signal source S is located outdoors, and the relay node Relay is configured with an electro-optical converter and an LED transmitter; the maximum coverage radius of the LED's optical beam is The radius of the protected area is ; Legitimate user B has a radius of The circle contains an RWP distribution, and its horizontal distance from the center O is . The eavesdropper E is in the annular region, i.e., the outer radius is... Inner radius is The inner elements follow a uniform distribution, and their horizontal distance from the center O is... Both B and E are equipped with a single photodetector (PD) receiver; in step 2-1), the signal source S transmits the electrical signal... The signal is transmitted to the relay node Relay, where it is received. Represented as: (1) In the above formula (1), the subscript SR represents the power line link between the source S and the relay node Relay; For PLC link attenuation, and It is a constant. For operating frequency, It is an exponential decay factor. Let S be the distance from the source S to the relay node Relay; Let S be the transmission power of the signal source S; For the channel gain of the power line link; Additional noise to the power line link; channel gain of the power line link. Its probability density function is: (2) The above formula (2) is for a random variable as The log-normal distribution and yes The mean and variance of the power line link; random switching of access devices and various low-power components in the power line link will generate additional noise, including background noise and impulse noise. Modeling this using a Poisson-Gaussian mixture statistical model, the additional noise... Represented as: (3) Among them, For background noise, It is impulse noise; The occurrence of transient impulse noise in the PLC link is represented by a discrete Poisson random process. and The model is based on Gaussian white noise with a mean of 0 and a variance of . and In the above formula (3), it is assumed that... and 、 Independent; Additional noise in power line links The probability density function is: (4) Among them, This represents the probability of impulse noise arriving at the channel. For arrival rate, It is the duration of the impulse noise; It is the power ratio of impulse noise to background noise; the instantaneous signal-to-noise ratio of the power line link from source S to relay node Relay. Represented as: (5) Among them, It is the average signal-to-noise ratio of the power line link when only background noise exists in the additional noise; It is the average signal-to-noise ratio of a power line link when both background noise and impulse noise are present in the additional noise. It is the instantaneous signal-to-noise ratio of a power line link when only background noise exists in the additional noise; It is the instantaneous signal-to-noise ratio of the power line link when both background noise and impulse noise are present in the additional noise; when only background noise exists in the power line link, the result is obtained using formulas (2) and (5). The probability density function is: (6) Among them, ， When the additional noise in the power line link includes both background noise and impulse noise, formulas (2) and (5) are used to obtain... The probability density function is: (7) Among them, ， Combining formula (4), formulas (6) and (7) are integrated to obtain... The probability density function is: (8) Integrating formula (8), we get The cumulative distribution function is: (9) Among them, , representing the complementary error function; in step 2-2), the user ， By using its own PD receiver to receive the signal decoded and forwarded from the relay node, then The received signal at the location is: (10) Among them, This is the signal after Relay decoding and forwarding; The visible light link contains additive white Gaussian noise with a mean of 0 and a variance of . ； From Relay to User The channel gain of the visible light link; from the relay to the user Channel gain of visible light links Represented as: (11) Among them, LED radiation angle This refers to the half-power luminous half-angle of an LED; Let be the Lambertian radiation order of the LED; The incident angle of the PD receiver. ， This refers to the field of view of the PD receiver; This represents the gain of the optical filter. For the gain of the optical concentrator, ， Here, H represents the reflection coefficient; H is the distance between the plane where the LED is located and the user. The vertical distance between the planes they are on; For the projection point of the LED on the ground and the user The horizontal distance between them; and These represent the effective physical detection area and detection sensitivity of the PD receiver, respectively, assuming... ,but ;make ， The squared channel gain of the visible light link is obtained as follows: (12) Users in visible light links instantaneous signal-to-noise ratio for: (13) Among them, This represents the average signal-to-noise ratio of a visible light link; The photoelectric conversion coefficient, The transmitted optical power of the LED embedded in the Relay; because legitimate user B is within a radius of The circle follows an RWP distribution, and the horizontal distance of B from the center O is... The probability density function is ， When considering two-dimensional topology, take ， ， ,but The probability density function is expressed as: (14) Using formulas (12), (13) and (14) and combining them with the variable substitution method, the instantaneous signal-to-noise ratio of legitimate user B is obtained. The probability density function is: (15) Among them, ； ， ， Integrating equation (15) yields the instantaneous signal-to-noise ratio of legitimate user B. The cumulative distribution function is: (16) Among them, Since the eavesdropper E is in the annular region, i.e., the outer radius is Inner radius is The inner distribution follows a uniform distribution, and the horizontal distance of E from the center O is... The probability density function can be expressed as: ， By combining formulas (12) and (13), the instantaneous signal-to-noise ratio of the eavesdropper E is obtained. The probability density function is: (17) Integrating equation (17) yields the instantaneous signal-to-noise ratio of the eavesdropper E. The cumulative distribution function is: (18) Among them, ， ， In step 3), the calculation process for the security interruption probability and confidentiality throughput of the hybrid PLC / VLC network is as follows: In the first hop, the instantaneous security capacity of the power line link... for: (19) In the second hop, the eavesdropper E tries its best to eavesdrop on the private information transmitted to the legitimate user B from the relay node Relay. Then the instantaneous security capacity of the visible light link is: for: (20) Among them, ， To calculate the maximum value; due to the application of a decoding and forwarding protocol in the relay node, the safety capacity of the indoor hybrid PLC / VLC network is... for: ， To find the minimum value; the safety interruption probability mentioned in 3-1) is defined as the safety capacity of the hybrid system. The probability that the value is less than the set target confidentiality threshold is expressed as: (21) Among them, For the probability of safe interruption; To perform probability calculations; Set the target confidentiality threshold; then, substitute formulas (8) and (9) in step 2-1) and formulas (15), (16), (17) and (18) in step 2-2) into formula (21) to obtain the security interruption probability of the indoor hybrid PLC / VLC network. for: (22) Among them, ； , ， ， ， ;3-2) The definition of the confidential throughput is the product of the target confidentiality threshold and the probability of secure and reliable transmission of the system, expressed as: (23) Where ST is the secure throughput; Substituting formula (22) into (23), the secure throughput ST of the indoor hybrid PLC / VLC network is obtained as follows: （24）。

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