Satellite-ground integrated network security transmission strategy

Abstract

The application belongs to the field of satellite-ground integrated network communication, and discloses a satellite-ground integrated network security transmission strategy of joint relay selection and threshold scheduling. Firstly, a general satellite-ground integrated network security transmission model is proposed, and then a joint relay selection and threshold-based user scheduling scheme is proposed, based on which acceptable system performance and complexity are obtained; in the case that multiple eavesdroppers exist, two scenarios are considered, one is a joint eavesdropping scenario, at this time all eavesdroppers cooperate with each other to eavesdrop information; two is a non-joint eavesdropping scenario, at this time the eavesdropper with the maximum signal-to-noise ratio among all eavesdroppers eavesdropping information channels is selected as the representative of eavesdropping information; based on this, the corresponding signal-to-noise ratio expression and the corresponding probability function are obtained; finally, the average security capacity analytical expression and the asymptotic closed expression are given, which provides a basis for evaluating the key parameters affecting the system security performance. The application upgrades the simple satellite-relay-user on-off judgment model to the anti-eavesdropping model for preventing eavesdropping, which is more practical and significant.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of satellite-terrestrial integrated network communication, and particularly relates to a satellite-terrestrial integrated network security transmission strategy combining relay selection and threshold scheduling. BACKGROUND

[0002] With the increasing spectrum utilization rate, and due to the wide area and broadcast characteristics of satellites, satellite security problems have followed. Due to the broadcast characteristics of satellites, satellites are more vulnerable to different types of security problems.

[0003] In the traditional sense, the security transmission problem of satellites is usually solved by high-level encryption, such as setting an encryption standard protocol, like the quantum encryption technology that has emerged in recent years. However, not only encryption means are progressing, but also the supercomputing and decoding capabilities of eavesdroppers are constantly developing. Today, traditional encryption means cannot guarantee security. In addition, it is realized that these protocols, such as tunnel transmission, can cause a large amount of transmission overhead, thereby significantly reducing the quality of service.

[0004] Unlike traditional cryptographic techniques, the physical layer security technology derived from the classical eavesdropping channel involved in the present application provides another promising direction for the security of satellite networks by utilizing the inherent randomness of the physical layer wireless fading channel. For example, the technology related to the present application mentioned in the literature (attachment) adopts an optimal user relay selection scheme to minimize the outage probability (OP: the probability that the actual channel signal-to-noise ratio is less than the pre-set appropriate signal-to-noise ratio lower limit value) to evaluate the system information transmission capability, that is, the link with the maximum signal-to-noise ratio from the relay to a user is used for information transmission, and the method is to detect all users and take the maximum signal-to-noise ratio link. However, this technology has the following limitations: first, for the case of multiple relay stations, the signal-to-noise ratio of each relay link and the signal-to-noise ratio of the ground user link need to be calculated and compared to select the best value, which has a large and complex calculation process and is prone to long delay, affecting the communication quality; second, it does not consider security problems such as interference, for example, how to define the outage when there is an eavesdropper. In view of the above problems, the present application reconfigures a satellite-terrestrial integrated network security transmission strategy combining relay selection and threshold scheduling, and not only uses the outage probability, but also further uses the security capacity to evaluate the physical layer security performance of the system, thereby providing theoretical guidance for more efficiently improving the physical layer security performance. SUMMARY

[0005] The purpose of the present application is to provide a satellite-terrestrial integrated network security transmission strategy that considers both joint eavesdropping and non-joint eavesdropping scenarios, solves the technical problem of physical layer security performance evaluation in both cases, and provides theoretical support for more efficiently improving the physical layer security performance.

[0006] In order to achieve the above object, solve the above technical problems, the technical scheme of the present application is as follows:

[0007] Step 1, first propose a general satellite-ground fusion network security transmission model, wherein multiple ground relays, multiple legal users and multiple illegal eavesdroppers are considered, as shown in Figure 1 ;

[0008] Step 2, secondly, a joint relay selection and threshold-based user scheduling scheme is proposed, based on which acceptable system performance and complexity are obtained, as shown in Figure 2 ;

[0009] Step 3, in the presence of multiple eavesdroppers, two scenarios are considered, one is a joint eavesdropping scenario, at this time all eavesdroppers cooperate to eavesdrop information; the second is a non-joint eavesdropping scenario, at this time the eavesdropper with the maximum signal-to-noise ratio is selected as the representative of eavesdropping information among all eavesdroppers eavesdropping information channels; based on this, the corresponding signal-to-noise ratio expression and the corresponding probability function are obtained.

[0010] Step 4, the average security capacity analytical expression and the asymptotic closed expression are given, which provides an effective method for evaluating the key parameters affecting the system security performance;

[0011] Compared with the prior art, the effective benefits of the present application are as follows:

[0012] 1. The present application is aimed at the case of multiple relay stations or users, without calculating the signal-to-noise ratio of each relay-to-ground user link, only needs to judge whether each link is suitable according to the pre-set threshold value, once suitable, no need to detect the subsequent relay-to-user link corresponding to the relay, but directly use it, so the calculation amount is greatly reduced and simplified, at the same time, it can also meet the actual situation, without producing long delay, and good communication quality is obtained.

[0013] 2. The present application fully considers the security problems such as interference, introduces the eavesdropping channel of eavesdroppers, and upgrades the simple satellite-relay-user on-off judgment model to the anti-eavesdropping model for preventing eavesdropping, which has more practical application significance.

[0014] 3. The present application not only quantifies the system performance by using the outage probability, but also further uses the security capacity to show the security of the system. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a structure schematic diagram of the satellite-ground fusion network model of the present application;

[0016] Figure 2 It is a structure schematic diagram of the user scheduling scheme of the present application;

[0017] Wherein: the abscissa is the signal-to-noise ratio of the main link

[0018] Figure 3 For the embodiment of joint eavesdropping, when L=2 and N=1, the average security capacity of the system changes with ;

[0019] Figure 4 For the embodiment of joint eavesdropping, when γ E =10db, ILS (non-frequency light fading), N=1 and different , the average security capacity of the system changes;

[0020] Figure 5 For the embodiment of non-joint eavesdropping, when L=6 and N=1, the average security capacity of the system changes with ;

[0021] Figure 6 For the embodiment of non-joint eavesdropping, when N=1, FHS (frequency heavy fading) or N=1, AS (uniform fading), the average security capacity of the system changes with different ;

[0022] Figure 7 For the embodiment when N=1 and L=2, the average security capacity of the system changes with under two eavesdropping conditions;

[0023] Figure 8 For the embodiment when N=3 and L=2, the average security capacity of the system changes with under two eavesdropping conditions;

[0024] Figure 9 For the embodiment in the present application, the percentage of user detection reduction changes with γ T under different M and . DETAILED DESCRIPTION

[0025] The present application mainly studies a satellite-ground integration network considering multi-ground relays, multi-legitimate users and multiple eavesdroppers. Due to the broadcast characteristics of the satellite in the satellite-ground integration network, the secure transmission of information becomes a big problem: in order to effectively improve the physical layer security of the system under certain complexity, the present application proposes a satellite-ground integration network secure transmission strategy combining relay selection and threshold scheduling. The present application will be further described in detail in combination with the drawings.

[0026] The steps of the satellite-ground integration network secure transmission strategy combining relay selection and threshold scheduling are as follows:

[0027] Step 1, first put forward a general feasible star-ground fusion network security transmission model, which considers multiple ground relays, multiple legal users and multiple illegal eavesdroppers, as shown in Figure 1

[0028] The star-ground fusion network model includes multiple ground relays, multiple legal users and multiple illegal eavesdroppers, where the number corresponds to N, M, L to represent. As Figure 1 , satellite S communicates with M legal users B through N relays R. As mentioned earlier, due to the wide coverage of the satellite, there are L eavesdroppers E around B. We assume that all nodes in the system are equipped with an antenna. Due to the influence of fog, rain, haze and shadow loss, we assume that there is no direct transmission between S and B. There are two time slots in the model, i.e. satellite transmission information to ground relay, and then relay transmission to legal users, but it is obvious that there will be more or less eavesdroppers eavesdropping channel information, at this time it is meaningful to study the physical layer security, that is, to ensure the maximum data transmission rate that can be sent in the case of eavesdropping nodes eavesdropping.

[0029] The following analyzes the signal transmission process in the model:

[0030] The first time slot of the transmission link is the signal between the satellite and the ground relay:

[0031]

[0032]

[0033] The second time slot of the transmission link not only has the signal between the relay and the legal user:

[0034]

[0035]

[0036] The second time slot of the transmission link also has the signal between the relay and the eavesdropper:

[0037]

[0038]

[0039] In the above formulas (1)-(6), p represents the transmission power, s(t) is the initial signal of the satellite beam, f / h represents the corresponding channel coefficient, and γ represents the corresponding channel signal-to-noise ratio.

[0040] The noise n is subject to Gaussian distribution:

[0041] N~(0,δ i 2 ). (7)

[0042] ​Subscript meaning: R ξ represents the jth eavesdropper (total L), B j represents the jth eavesdropper (total L), B i represents the jth eavesdropper (total L), B represents the jth eavesdropper (total L), B represents the jth eavesdropper (total L), B represents the jth eavesdropper (total L), B

[0043] Step 2, the structure of the joint relay selection and threshold-based user scheduling scheme is shown in Figure 2

[0044] The corresponding joint relay selection and threshold-based user scheduling scheme is described in detail as follows:

[0045] Step 2-1, we detect the signal-to-noise ratio of the satellite and the ξ relays R, and then set a threshold γ T , and check the signal-to-noise ratio of the first ground user B to the ξ relays R. If the signal-to-noise ratio is higher than γ T , this transmission link is used. Otherwise, if the signal-to-noise ratio is lower than γ T , the link of the ξ relays R to the second ground user B will be selected regardless of the signal-to-noise ratio of this link;

[0046] Step 2-2, in the second time slot, the ξ relays R first check the second transmission link, if the signal-to-noise ratio of the link is higher than γ T , then the link will always be used. Otherwise, the third link to B will be used;

[0047] Step 2-3, when reaching the Mth link of the ξ relays R to B, similarly, if the signal-to-noise ratio is higher than γ T , the link will always be used, otherwise, the first link will be used;

[0048] Step 2-4, according to the relay selection protocol, the signal-to-noise ratio of the satellite to the ξ relays R to B link is calculated. Then among all the links, the best link with the maximum average safe capacity is selected as the final transmission link.

[0049] The meaning of the theoretical formula represented by the joint relay selection protocol and user scheduling scheme has been given in detail above, and will not be repeated here.

[0050] ​Step 3, in the presence of multiple eavesdroppers, consider two scenarios, one is joint eavesdropping scenario, at this time all eavesdroppers cooperate with each other to eavesdrop on information; Two is non-joint eavesdropping scenario, at this time the eavesdropper with the maximum signal-to-noise ratio is selected as the representative of eavesdropping information among all eavesdroppers eavesdropping on the information channel. Based on this, the corresponding signal-to-noise ratio expression and the corresponding probability function are obtained.

[0051] For joint eavesdropping: approximate to the sum of each signal-to-noise ratio, the signal-to-noise ratio of the eavesdropping link can be expressed as

[0052]

[0053] Non-joint eavesdropping: the link of the best eavesdropper is representative, and the signal-to-noise ratio of the eavesdropping link can be expressed as

[0054]

[0055] For ground link: that is, relay to user or eavesdropping end, follow Rayleigh fading channel, the probability density function and cumulative distribution function of the link signal-to-noise ratio are as follows:

[0056]

[0057]

[0058] In the joint eavesdropping scenario, the eavesdroppers cooperate with each other, and the probability density function and cumulative distribution function of the eavesdropping signal-to-noise ratio are as follows:

[0059]

[0060]

[0061] In the non-joint scenario: the eavesdroppers are independent, and the maximum signal-to-noise ratio is taken as the final value of the link, and the cumulative distribution function and the probability density function of the eavesdropping signal-to-noise ratio are as follows:

[0062]

[0063]

[0064] For the primary user link, including two channels of satellite to relay and relay to user:

[0065] For satellite link: that is, satellite to ground relay end link, follow Rayleigh fading channel, according to analysis and derivation, can be expressed as:

[0066]

[0067]

[0068] where m: fading factor i.e. number of beam types Ω: average power of line-of-sight link 2b: average power of multipath link (x) k : represents pochhammer function;

[0069] For the relay-to-user link, subject to Rayleigh fading channel, following the joint relay selection protocol and user scheduling scheme, equation (8) can be written as:

[0070]

[0071] Using the definition of cumulative distribution function, it can be expressed as:

[0072]

[0073] Substituting equation (15) into the above equation, the distribution of relay-to-user link is obtained as:

[0074]

[0075] And from equation (8), the primary user link distribution is:

[0076]

[0077] Substituting equations (20) and (24) into equation (25), we have:

[0078]

[0079]

[0080] For the asymptotic solution analysis under high signal-to-noise ratio, we have

[0081]

[0082] It can be known that the above satellite-to-relay distribution (22) and relay-to-user distribution (26) will be changed, and according to the analysis and derivation, the new primary user link probability density function is obtained as follows:

[0083]

[0084] Equation (27) will be used in the next step to calculate the average safe capacity.

[0085] Step 4, according to the principle of relay selection protocol and the proposed user scheduling scheme, from equation (10), the average safe capacity is obtained as:

[0086]

[0087] where two unknown functions one is formula (17) or (18), the other is the signal-to-noise ratio probability distribution function of the primary user link from satellite to legitimate user, that is, formula (26).

[0088] Similarly, the defined asymptotic average safety capacity is:

[0089]

[0090] Here there are two unknown functions, one is the former formula (17) or (18), and the other is the expression (26) of the signal-to-noise ratio probability density function of the primary user link from satellite to legitimate user under high signal-to-noise ratio.

[0091] Finally, the percentage of the number of legitimate user detections is also introduced (advantage), to verify the advantage of the proposed scheme: defined as follows

[0092]

[0093] In formula (40), N represents the number, AUE represents the average number of user detections, and it is obvious that it is related to the set threshold.

[0094] The subsequent derivation is brought into simulation, and the results are as follows, which are used to verify and analyze:

[0095] In general, it is assumed that the Gaussian white noise power σ = 1, and the signal-to-noise ratio of the primary link M = 3, threshold γ T = 10db, which is for Figure 3 — Figure 8 In order to simplify the analysis, therefore, we set Figure 3 - Figure 7 N = 1; the system and channel fading parameters are as shown in Tables 1 and 2.

[0096] Table 1 Simulation system parameter table

[0097] Table 2 Simulation channel parameters (AS, FHS, ILS) table

[0098]

[0099] Table 1

[0100] Fading type m b Ω Frequency heavy fading (FHS) 1 0.063 0.0007 Average fading (AS) 5 0.251 0.279 Non-frequency light fading (ILS) 10 0.158 1.29

[0101] Table 2.

Claims

1. A method for secure transmission of a satellite-terrestrial converged network, which combines relay selection and threshold scheduling, characterized in that, Comprising the following steps: Step 1, construct a general feasible satellite-ground fusion network security transmission model, wherein multiple ground relays, multiple legal users and multiple illegal eavesdroppers are considered; The model establishment in step 1 is specifically represented as: The satellite-ground fusion network model comprises N ground relays, M legal users and L illegal eavesdroppers, the satellite S communicates with the M legal users B through the N relays R, and there are L eavesdroppers E around the B; it is assumed that all nodes in the system are equipped with an antenna, and it is assumed that there is no direct transmission between S and B, so there are two time slots in the model, i.e. the satellite transmits information to the ground relay, and then the relay transmits to the legal user; the signal transmission process in the model is as follows: The first time slot of the transmission link is the signal between the satellite and the ground relay: The second time slot of the transmission link not only has the signal between the relay and the legal user: The second time slot of the transmission link also has the signal between the relay and the eavesdropper: In the above formulas (1)-(6), p represents the transmission power, s(t) is the initial signal of the satellite beam, f / h represents the corresponding channel coefficient, γ represents the corresponding channel signal-to-noise ratio, and the noise n is subject to Gaussian distribution: N ~ (0, δ i 2 ). (7) The subscript means: ξ refers to a certain relay link, so ξ = 1, 2,..., N, wherein N is the number of relays; R ξ represent the jth eavesdropper, total L, B j represent the jth eavesdropper, total L, B i represent the ith user terminal, total M; S represents a satellite with multiple beam antennas, k represents the kth beam coverage of the satellite; as denotes the channel signal-to-noise ratio between the ith user terminal and the jth relay, denotes the transmit power of the jth relay, denotes the channel coefficient between the kth beam of the satellite and the jth relay; Step 2, design a joint relay selection and threshold-based user scheduling scheme to obtain acceptable system performance and complexity; specifically comprising the following steps: 2.1 We check the signal to noise ratio of the satellite to the hub R and set a threshold γ T and check the signal to noise ratio of the first ground user B to the hub R; if the signal to noise ratio is higher than γ T then use this link; otherwise, if the signal to noise ratio is lower than γ T then the link from the hub R to the second ground user B will be selected regardless of the signal to noise ratio of this link; 2.2 In the second time slot, the relay R checks first the second transmission link. If the signal-to-noise ratio of this link is higher than γ T , then this link will always be used; otherwise, the third link to B will be used. 2.

3. When reaching the Mth link of some ξ relays R to B, again, if the signal-to-noise ratio is higher than γ T then always use this link, otherwise use the first one; 2.4, according to the relay selection protocol, the signal-to-noise ratio of the satellite to the R to B link of the ξ relays is calculated, and then the best link with the maximum average security capacity is selected from all the links as the final transmission link; with a pre-set threshold γ T for an interval Relay selection protocol: The security capacity of this satellite link is calculated using this: and the value is required to be greater than zero In formula (10), denotes the channel capacity of a certain user receiving end, denotes the channel capacity of a certain eavesdropping receiving end; Finally, select the link with the maximum security capacity among the channel links corresponding to the N relay ends for transmission: Step 3, in the presence of multiple eavesdroppers, consider two scenarios, one is a joint eavesdropping scenario, in which all eavesdroppers cooperate to eavesdrop on the information, and the other is a non-joint eavesdropping scenario, in which the eavesdropper with the maximum signal-to-noise ratio among all eavesdroppers eavesdropping on the information channel is selected as the representative eavesdropper; based on this, the corresponding signal-to-noise ratio expression and the corresponding probability function are obtained For joint eavesdropping: approximate to the sum of each signal-to-noise ratio, the signal-to-noise ratio of the eavesdropping link can be represented as Non-joint eavesdropping: the link of the best eavesdropper is representative, and the signal-to-noise ratio of the eavesdropping link can be represented as For the ground link: i.e. the relay to user or eavesdropping end, it follows the Rayleigh fading channel, and the probability density function and cumulative distribution function of the link signal-to-noise ratio are as follows: In the joint eavesdropping scenario, the eavesdroppers cooperate with each other, and the probability density function and cumulative distribution function of the eavesdropping signal-to-noise ratio are as follows: In the non-joint eavesdropping scenario: the eavesdroppers are independent, and the maximum signal-to-noise ratio is taken as the final value of the link, and the cumulative distribution function and the probability density function of the eavesdropping signal-to-noise ratio are as follows: For the primary user link, it includes two channels: satellite to relay and relay to user: For the satellite link: i.e. the satellite to ground relay end link, it follows the Rice fading channel, and according to the analysis and derivation, it can be represented as: where m: fading factor i.e. number of beam types Ω: average power of line-of-sight link 2b: average power of multipath link (x) k : represents the pochhammer function; For the relay-to-user link, subject to Rayleigh fading channel, following the joint relay selection protocol and the user scheduling scheme, equation (8) can be written as Using the definition of the cumulative distribution function, it can be expressed as Substituting equation (15) into the above equation, the distribution of the relay-to-user link is obtained as From equation (8), the main user link distribution is Substituting equations (20) and (24) into equation (25), we have For the asymptotic solution analysis under high signal-to-noise ratio, equation (8) can be written as It can be seen that the above satellite-to-relay distribution (22) and the relay-to-user distribution (26) will be changed, and according to the analysis and derivation, the new main user link probability density function is obtained as Equation (27) will be used in the next step to calculate the average safety capacity. Step 4, according to the principle of the relay selection protocol and the proposed user scheduling scheme, equation (10) can be defined as the average safety capacity: where two unknown functions are one of equations (17) or (18), and the other is the signal-to-noise ratio probability distribution function of the main user link from the satellite to the legitimate user, i.e. equation (26). Similarly, the asymptotic average safety capacity defined is Here there are two unknown functions, one is the previous equation (17) or (18), and the other is the expression of the signal-to-noise ratio probability density function of the main user link from the satellite to the legitimate user under high signal-to-noise ratio (26).

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