CN111641991B - Multi-relay two-hop network secure transmission method based on data caching - Google Patents

Abstract

The invention discloses a multi-relay two-hop network security transmission method based on data cache, which obtains the channel security threshold from the source node to the relay node according to the link interruption probability from the source node to the relay node; The link interruption probability of the node obtains the channel security threshold from the source node to the relay node; according to the relay buffer status and the number of safe links, the link selection strategy is formulated; according to the determined link selection strategy, the network channel transition matrix and Steady-state probability, get the network security interruption probability, realize transmission. In the present invention, the interruption probability of the channel is considered when the link is selected, and the security of the network can be further improved, which is superior to the traditional safe transmission scheme based on data cache.

Description

A secure transmission method of multi-relay two-hop network based on data cache

technical field

The invention belongs to the technical field of wireless communication, and in particular relates to a multi-relay two-hop network security transmission method based on data cache.

Background technique

The rapid development of wireless technology and devices has brought a large amount of personal and private information interaction, such as bank account information, personal health information, etc. The security of such information brings important challenges to the development of wireless communication networks. Although the upper-layer key encryption technology can protect information security, the upper-layer key technology assumes that the eavesdropping node has limited capabilities and the encryption algorithm is complex, and cannot be applied to communication networks with good device capabilities. The physical layer security technology uses the wireless channel characteristics to encrypt, which can well supplement the above shortcomings. Cooperative relay technology can use relay to improve the security of the network, but the fixed relay mode limits the network performance to the worst hop. The cache-based relay network can solve the above problems well. Although the security of the cache-based cooperative relay network has been studied, the link selection strategy of the network does not consider the probability of information security interruption, so the performance improvement is limited.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide a multi-relay two-hop network security transmission method based on data cache to optimize the performance of the traditional scheme, aiming at the deficiencies in the above-mentioned prior art.

The present invention adopts following technical scheme:

A multi-relay two-hop network security transmission method based on data cache, comprising the following steps:

S1. Obtain the channel security threshold from the source node to the relay node according to the link interruption probability from the source node to the relay node; obtain the channel security threshold from the source node to the relay node according to the link interruption probability from the relay node to the destination node;

S2. Formulate a link selection strategy according to the relay cache state and the number of secure links;

S3. According to the link selection strategy determined in step S2, analyze the channel transition matrix and the steady state probability of the network to obtain the safety interruption probability of the network, and realize the transmission.

时，

为最大允许安全中断概率，源节点和中继R_i之间链路为安全，则源节点和中继R_i的链路必须满足

其中

为源节点和中继R_i在第t个时隙的信道功率增益，Υ_ar源节点和中继之间信息安全的最小门限；Specifically, in step S1, the safety interruption probability of the first hop in the t-th timeslot

hour,

For the maximum allowable safety interruption probability, the link between the source node and the relay R _i is safe, then the link between the source node and the relay R _i must satisfy:

in

is the channel power gain of the source node and the relay R _i in the t-th time slot, Y _ar is the minimum threshold of information security between the source node and the relay;

时，中继R_i和目的节点之间链接实现连接；链路选择策略为：Safe outage probability for the second hop in the t-th slot

When , the link between the relay R _i and the destination node realizes the connection; the link selection strategy is:

表示源节点和中继之间的链接是安全的；

表示中继和目的节点之间的链路安全，中继R_i和目的节点之间链路必须满足

为中继R_i和目的节点在第t个时隙的信道功率增益，Υ_rb中继R_i和目的节点之间信息安全的最小门限。where Ψ(Q _k ) is the buffer state of R _k ,

Indicates that the link between the source node and the relay is secure;

Represents the link security between the relay and the destination node, the link between the relay R _i and the destination node must satisfy

For the channel power gain of the relay R _i and the destination node in the t-th time slot, _Yrb is the minimum threshold of information security between the relay R _i and the destination node.

Specifically, in step S2, the link selection strategy is specifically:

为源节点和中继R_i的信道功率增益，

为中继R_i和目的节点的信道功率增益，λ_ae为源节点和窃听节点之间的信道方差，λ_re为中继节点和窃听节点之间的信道方差；

表示选择源节点和中继之间的链接是安全且信道功率增益最大中继；

表示选择中继节点和目的节点之间的链接是安全且信道功率增益最大中继。Among them, R _opt is the optimal relay selected, R _k is the kth relay, Ψ(Q _k ) is the state of the cache Q _k of R _k , L is the maximum data cache,

is the channel power gain of source node and relay R _i ,

is the channel power gain of the relay R _i and the destination node, λ _ae is the channel variance between the source node and the eavesdropping node, and λ _re is the channel variance between the relay node and the eavesdropping node;

Indicates that the link between the source node and the relay is selected to be a secure relay with the largest channel power gain;

Indicates that the link between the selected relay node and the destination node is a secure relay with maximum channel power gain.

Further, the probability that there is no secure link in the network is:

Among them, λ _ar is the channel variance between the source node and the relay node, and λ _rb is the channel variance between the relay node and the destination node.

Further, according to the link selection scheme, the probability that there are M ₁ legal links between the source node and the relay node is

Among them, M is the number of relays.

Further, according to the link selection scheme, the probability of having M ₂ legal links between the relay node and the destination node is:

其中s_n表示第n个时隙网络状态，

表示第i个中继的缓存状态；Let the state space of the network be

where s _n represents the network state of the nth slot,

Indicates the cache status of the i-th relay;

Specifically, in step S3, according to the link selection strategy, the probability that the system transmits from state s _n to state s _l is an _,l , then the stationary state of the network is:

π=(A-I+B) ^-1 b

Among them, A is the transition matrix, b is a vector with all 1 elements, I is the identity matrix, and B is a matrix with all 1 elements.

Further, according to the system state, the security interruption probability of the network is:

是系统在状态s_n是的中断概率。in,

is the outage probability of the system in state s _n .

Compared with the prior art, the present invention at least has the following beneficial effects:

The present invention is a multi-relay two-hop network security transmission method based on data cache, and proposes a link selection strategy based on security interruption; according to the available and secure link set, a state transition matrix of Markov chain is constructed , and derive the steady-state probability; according to the above-mentioned steady-state probability, the closed-form expression of the security interrupt probability of the proposed scheme is deduced; finally, the numerical results show that the interrupt-driven secure transmission scheme proposed in the present invention is superior to the traditional cache-assisted security transmission scheme.

Further, the present invention first analyzes the channel security rate from the source node to the relay and the relay to the destination node, and analyzes the corresponding security interruption probability. According to the obtained security interruption probability, the channel security thresholds of the source node to the relay and the relay to the destination node are deduced.

Further, based on the above-mentioned threshold and relay cache state, the present invention proposes a new link selection strategy based on safety interruption probability, which takes into account information security and reliability to improve network performance.

Further, according to the above-mentioned link selection strategy, the present invention utilizes a Markov chain to characterize the state transition probability in the system and derives the state transition matrix, and then obtains the steady state probability of the system, which provides mathematics for performance analysis. tool.

Further, according to the above-mentioned steady state probability, the present invention analyzes the information security interruption probability of the scheme and obtains a closed-form expression.

To sum up, the present invention considers the interruption probability of the channel during link selection, which can further improve the security of the network, which is superior to the traditional security transmission scheme based on data buffering.

The technical solutions of the present invention will be further described in detail below through the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a buffer-assisted safe transmission diagram proposed by the present invention;

Fig. 2 is when g _sr ≥ g _rd , the relation diagram of secrecy interruption probability and average channel power gain g _rd ;

Fig. 3 is a graph of confidentiality interruption probability and target secrecy rate Rsec;

FIG. 4 is an upper bound graph of the probability of secret outage and the probability of licensed secret outage.

Detailed ways

Referring to FIG. 1, the present invention provides a multi-relay two-hop network security transmission method based on data caching. The source node lice wants to transmit information to the destination node Bob safely and reliably, and the eavesdropping node Eve will perform the transmission data of Alice. tapping. The direct channel quality between Alice and Bob is poor due to massive fading or interference. For secure transmission between Alice and Bob, the assistance of the relay is required, but the eavesdropper can receive private information from Alice and the relay;

Each relay has only one antenna and works in half-duplex mode. Each relay has a data buffer, which is represented by Q _i ; the length of the data buffer is L; in this system, each frame is equally divided into one A series of time slots, each of duration T. In each time slot, there is only one relay to receive or forward the private information; the system experiences Rayleigh flat block fading, which means that the channel state information remains constant in each time slot and changes independently in adjacent time slots.

Referring to FIG. 1, a method for secure transmission of a multi-relay two-hop network based on a data cache of the present invention includes the following steps:

S1. Design a link selection strategy to maximize the privacy interruption probability;

In the t-th time slot, if the relay _Ri is selected to receive Alice's private information, the received information is:

是Alice和R_i在第t个时隙的信道系数；x_a[t]是第t个时隙Alice的私密信息；

是R_i在第t个时隙接收到噪声，此私密信息被解码并存储在R_i的缓存中，同时被窃听的私密信息为：Among them, p _a is Alice's transmit power;

is the channel coefficient of Alice and _Ri in the t-th time slot; x _a [t] is the private information of Alice in the t-th time slot;

It is R _i that receives the noise in the t-th time slot, the private information is decoded and stored in the buffer of R _i , and the private information that is eavesdropped at the same time is:

where _hae [t] is the channel system between Alice and the eavesdropper in the t-th slot, and _ne [t] is the noise received by the eavesdropper in the t-th slot.

After _k slots, if Ri forwards this private information, the signal received by Bob is:

是R_i和Bob在第(k+t)时隙的信道系统；x_ri[t+k]是第(t+k)时隙R_i转发的私密信息；n_b[t+k]是(t+k)时隙Bob接受的噪声。where P _r is the transmit power of R _i ;

is the channel system of Ri and Bob in the ( _k +t)th time slot; x _ri [t+k] is the private information forwarded by Ri in the (t+k) _th time slot; n _b [t+k] is ( t+k) Noise received by Bob at slot.

Similarly, the private information eavesdropped by the eavesdropper is:

是R_i和窃听者在第(t+k)时隙的信道系统，n_e[t+k]是窃听者在(t+k)时隙接收到的噪声。in,

is the channel system of Ri and the eavesdropper in the (t+ _k )th time slot, and _ne [t+k] is the noise received by the eavesdropper in the (t+k)th time slot.

When the relay _Ri is selected to receive Alice's private information in the t-th time slot, the information rate of _Ri is:

是Alice和R_i在第t个时隙的信道功率增益，N₀为噪声方差。in,

is the channel power gain of Alice and _Ri in the t-th time slot, and N ₀ is the noise variance.

The eavesdropping rate for eavesdroppers is:

The safe rate of Alice and _Ri in the t-th slot is:

Among them, (a) ⁺ =max(a,0), since the channel state information of the eavesdropping channel cannot be obtained, the security interruption probability is used to measure the security performance.

So the safe outage probability is:

在第t时隙中，Alice和R_i之间的链接只有在

时才是安全的，因此可以得到Among them, R _s is the target security interruption probability, and λ _ae is the channel variance from Alice to the eavesdropping node. Let the maximum allowable safe interruption probability be

In the t-th slot, the link between Alice and _Ri is only

is safe when

时得出g_ari[t]≥Υ_ar，此时信道是安全的。when

When we get g _ari [t]≥Υ _ar , the channel is safe at this time.

In time slot t+k, R _i forwards the security information, then Bob's received information rate is

The eavesdropper's eavesdropping rate at time t+k is:

Therefore, the secrecy rate of the second hop in the t+kth slot is:

According to the target safety rate R _s , the safety interruption probability of the second hop can be obtained as:

Among them, _λre is the channel variance from the relay node to the eavesdropping node.

则在

的条件下，R_i与Bob的链路是安全的，即：Given the maximum safe outage probability threshold

then in

Under the condition of , the link between _Ri and Bob is safe, namely:

According to the network available links and data cache status, the present invention proposes the following link selection strategy:

表示Alice和中继之间的链接是安全的且信道质量较好，并且相应中继的缓存具有存储私密信息的空间；

表示中继和Bob之间的链接是安全的且信道质量较好，并且相应中继的缓存具有要传输的私密信息。Among them, Ψ(Q _k ) is the cache state of the relay R _k .

Indicates that the link between Alice and the relay is secure and the channel quality is good, and the cache of the corresponding relay has space to store private information;

Indicates that the link between the relay and Bob is secure and the channel quality is good, and the cache of the corresponding relay has private information to be transmitted.

S2. According to the selected link selection strategy, when the link satisfies g _ari ≥ Υ _ar or g _rib ≥ Υ _rb , it is safe; otherwise, there will be no safe transmission link available, and the probability at this time is:

Among them, the subscript of P _null represents the probability that there is no available link for secure transmission, λ _ar represents the variance of the channel between Alice and the relay, and λ _rb represents the variance of the channel between the relay and Bob.

At this time, the probability that the system has at least one safe link is 1-P _null . Possibility of M ₁ links between Alice and the relay in slot t:

Similarly, in the t-th time slot, there are M ₂ links between the relay and Bob:

In the t-th time slot, the state space of the network is expressed as:

表示R_i在状态s_n的缓存状态。根据所提出的链路选择策略，系统状态以概率从s_n转移到下一个状态s_l的概率为：in,

Represents the cached state of R _i in state _sn . According to the proposed link selection strategy, the probability that the system state transitions from _sn to the next state s _l with probability is:

Among them, P _sr is the probability of selecting a link from Alice to the relay link set, P _rb is the probability of selecting a link in the relay and Bob link set, Ω ⁺ is the case where Alice is selected to send at _sn , Ω ^- is the case where relay forwarding is selected at _sn .

P _sr is the probability of choosing a link from Alice to the relay link set:

Then P _rb =1-P _sr

Then according to the state space of the system, the stationary state of the system is derived as:

π=(A-I+B) ^-1 b

Among them, A is the transition matrix, b is a vector with all 1 elements, I is the identity matrix, and B is a matrix with all 1 elements.

S3. Derive the closed-form expression of the secret interruption and the probability and secrecy rate of the scheme, and establish the queuing theory to calculate the information delay;

Referring to Figure 4, according to the eavesdropping coding theory, if the system security rate is less than R _s , the private information will suffer from security interruption. Therefore, in the proposed link selection strategy, the system safety interruption probability is:

是状态s_n的安全中断概率：in,

is the safe outage probability for state _sn :

Among them, M is the number of relays in the network, λ _ar represents the variance of the channel between Alice and the relay, λ _rb represents the variance of the channel between the relay and Bob,

All link selection strategies in the present invention take into account the interruption of the link, which can avoid the security interruption during link selection, thereby improving the security of the network. According to the safe outage probability of the system, the safe outage conditions that can be obtained by this scheme can be obtained, which provides guidance for the practical use of this scheme.

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all embodiments. The components of the embodiments of the invention generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the invention provided in the accompanying drawings are not intended to limit the scope of the invention as claimed, but are merely representative of selected embodiments of the invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Simulation

1. Figure 2 shows the relationship between the safe outage probability and the average channel power gain between the relay and Bob. It can be observed in the figure that the theoretical results are in good agreement with the simulation results. In addition, the safe outage probability is a decreasing function of g _rd . A larger value of g _rd indicates that the source node and the relay have more power to ensure secure transmission in the first and second hops. Therefore, the probability of a safe outage decreases as the _grd decreases. More relays will increase the variety of options and the likelihood of security disruption will decrease. In the traditional maximum ratio scheme, link security is not considered and the probability of security outage will increase.

2. Figure 3 shows the relationship between the security interruption probability and the target confidentiality rate R _s ; in the figure, the security interruption probability is an increasing function of R _s ; a larger value of R _s indicates that it is challenging to securely transmit private information, and the available links will reduce. Therefore, the probability of safe outage will increase with the increase of _Rs; the increase of cache size and the increase of the number of relays will increase the diversity of link selection and reduce the possibility of safe outage; for the traditional maximum ratio scheme , without considering whether the transmission link is available for safe transmission, which leads to an increased probability of safe outage.

To sum up, the present invention is a multi-relay two-hop network security transmission method based on data cache. First, the security interruption probability of two-hop transmission is analyzed to obtain the minimum threshold of information security transmission; then, a security interruption probability based method is proposed. The link selection strategy ensures the security of information and the efficiency of information transmission. According to the proposed strategy, the state transition probability of the system is analyzed and the steady state probability is obtained, and then the safety interruption probability of the system is analyzed, and the corresponding closed-form solution is obtained. The simulation results show that the proposed scheme of the present invention can improve the security of the system.

The above content is only to illustrate the technical idea of the present invention, and cannot limit the protection scope of the present invention. Any modification made on the basis of the technical solution proposed in accordance with the technical idea of the present invention falls within the scope of the claims of the present invention. within the scope of protection.

Claims (3)

1. A multi-relay two-hop network security transmission method based on data caching is characterized by comprising the following steps:

s1, obtaining a channel safety threshold from the source node to the relay node according to the link interruption probability from the source node to the relay node; obtaining the interruption threshold from the relay node to the destination node according to the interruption probability of the link from the relay node to the destination node, and the safe interruption probability of the first hop in the t-th time slot

When the temperature of the water is higher than the set temperature,

for maximum allowed safe outage probability, source node and relay R_iThe link between the source node and the relay R is safe_iMust satisfy

Wherein

As source node and relay R_iChannel power gain at t-th time slot, gamma_arA minimum threshold of information security between the source node and the relay;

probability of safe interruption of second hop in t time slot

Time, relay R_iThe connection with the destination node is realized through the link; the link selection policy is:

therein, Ψ (Q)_k) Is R_kIn the buffer state of (a) to (b),

indicating that the link between the source node and the relay is secure;

indicating link security between relay and destination node, relay R_iAnd the link between the destination node must satisfy

Wherein,

is a relay R_iAnd the channel power gain, gamma, of the destination node in the t-th time slot_rbRelay R_iAnd the minimum threshold of information security between the destination node;

s2, according to the relay buffer state and the number of the safe links, a link selection strategy is formulated, and the link selection strategy specifically comprises the following steps:

wherein，R_optFor the selected optimal relay, R_kFor the kth relay, Ψ (Q)_k) Is R_kCache Q of_kL is the maximum data cache,

as source node and relay R_iThe channel power gain of (a) is,

is a relay R_iAnd channel power gain, λ, of the destination node_aeIs the channel variance, lambda, between the source node and the eavesdropping node_reIs the channel variance between the relay node and the eavesdropping node;

indicating that the link between the selected source node and the relay is safe and the channel power gain is maximum;

indicating that the link between the selected relay node and the destination node is safe and the channel power gain is maximum; according to the link selection scheme, there is M between the source node and the relay node₁The probability of a legitimate link being

Wherein M is the number of relays;

according to the link selection scheme, there is M between the relay node and the destination node₂The probability of a legal link being validated is:

setting the state space of the network as

Wherein s is_nIndicating the network status of the nth slot,

indicating the buffer status of the ith relay;

s3, according to the link selection strategy determined in the step S2, analyzing the channel transfer matrix and the steady-state probability of the network to obtain the safe interruption probability of the network, realizing transmission, and according to the link selection strategy, the system is in a state S_nIs transmitted to the state s_lHas a probability of_n,lThe steady state of the network is then:

π＝(A-I+B)^-1b

where A is a transition matrix, B is a vector whose elements are all 1, I is an identity matrix, and B is a matrix whose elements are all 1.

2. The method for secure transmission in a multi-relay two-hop network based on data caching of claim 1, wherein in step S2, the probability that there is no secure link in the network is:

wherein λ is_arIs the channel variance, lambda, between the source node and the relay node_rbIs the channel variance between the relay node and the destination node.

3. The method for secure transmission over the multi-relay two-hop network based on the data cache of claim 1, wherein in step S3, according to the system status, the network security outage probability is:

wherein,

is the system is in state s_nIs.

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