CN108418651B - Safe transmission method of bidirectional wireless power supply relay system - Google Patents

Safe transmission method of bidirectional wireless power supply relay system Download PDF

Info

Publication number
CN108418651B
CN108418651B CN201810118747.5A CN201810118747A CN108418651B CN 108418651 B CN108418651 B CN 108418651B CN 201810118747 A CN201810118747 A CN 201810118747A CN 108418651 B CN108418651 B CN 108418651B
Authority
CN
China
Prior art keywords
relay
node
information
gamma
signal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
CN201810118747.5A
Other languages
Chinese (zh)
Other versions
CN108418651A (en
Inventor
张超
蔡颖
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Xian Jiaotong University
Original Assignee
Xian Jiaotong University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xian Jiaotong University filed Critical Xian Jiaotong University
Priority to CN201810118747.5A priority Critical patent/CN108418651B/en
Publication of CN108418651A publication Critical patent/CN108418651A/en
Application granted granted Critical
Publication of CN108418651B publication Critical patent/CN108418651B/en
Expired - Fee Related legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/40—Jamming having variable characteristics
    • H04K3/43—Jamming having variable characteristics characterized by the control of the jamming power, signal-to-noise ratio or geographic coverage area
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes
    • H04B5/72—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes for local intradevice communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B5/00—Near-field transmission systems, e.g. inductive or capacitive transmission systems
    • H04B5/70—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes
    • H04B5/79—Near-field transmission systems, e.g. inductive or capacitive transmission systems specially adapted for specific purposes for data transfer in combination with power transfer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/80—Jamming or countermeasure characterized by its function
    • H04K3/82—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection
    • H04K3/827—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection using characteristics of target signal or of transmission, e.g. using direct sequence spread spectrum or fast frequency hopping
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/14—Relay systems
    • H04B7/15—Active relay systems
    • H04B7/155—Ground-based stations
    • H04B7/15592—Adapting at the relay station communication parameters for supporting cooperative relaying, i.e. transmission of the same data via direct - and relayed path

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Radio Relay Systems (AREA)

Abstract

The invention discloses a safe transmission method of a bidirectional wireless power supply relay system. The method mainly comprises three stages: wireless energy transmission, source broadcasting and relay forwarding. Before information transmission, an information source and a target node jointly send an energy signal to a relay node, so that the relay node obtains energy required by information forwarding and channel information, and an optimal weight coefficient vector is solved. In the information source broadcasting stage, the information source sends information, and meanwhile, the target node sends an interference signal to ensure the safety of communication. In the relay forwarding stage, the relay node calculates an optimal beam vector by using the obtained channel information, and forwards a weighted information to the destination node, thereby further improving the security performance of transmission. In addition, the invention provides a distributed power allocation algorithm which maximizes the average privacy capacity of the system. Compared with the traditional transmission mode, the invention can effectively improve the security performance of transmission.

Description

Safe transmission method of bidirectional wireless power supply relay system
Technical Field
The invention belongs to the technical field of mobile communication, and particularly relates to a safe transmission method of a bidirectional wireless power supply relay system.
Background
The rapid development of the information society, the higher and higher communication requirements of people and the exponential growth of data promote the forward development of the wireless communication technology at an unprecedented speed. It is well known that the quality of a communication system is generally measured in terms of effectiveness, reliability and security. Among various communication systems, wireless communication systems are more vulnerable to security threats than wired transmission systems in which the physical transmission medium is relatively closed due to the openness of the physical transmission medium, the mobility of wireless terminals, and the diversity and variability of wireless communication network topologies. The information security mechanism of the existing wireless communication system is mainly transplanted to the wired system, and the information security technology in the traditional wireless communication system is mainly focused on the network layer and above layers. With the innovation of the channel coding technology, the engineering of the multi-carrier technology can be realized, and the multi-antenna technology and the cooperative relay technology appear, which lead the research trend of the wireless communication technology to different degrees and greatly enrich the physical layer resources of the wireless communication. And with the rapid development of decoding devices, conventional encryption techniques are encountering unprecedented challenges. Therefore, how to utilize the inherent characteristics of the wireless channel, such as shadow fading, path loss, and multipath, to realize reliable transmission of information in the physical layer sense is further receiving much attention.
The cooperative relay technology utilizes distributed signal transmission and processing of a plurality of single-antenna terminals to construct a virtual multi-antenna array so as to obtain a novel space diversity gain, namely cooperative diversity. The technology can effectively improve multiple key performance indexes such as throughput, reliability, coverage and the like of wireless transmission. At present, a cooperative relay technology becomes one of the key technologies of fourth-generation mobile communication, and is specifically applied in a cellular network, so that cell coverage can be expanded, blind area coverage can be completed, system throughput can be improved, and application targets such as temporary and emergency network deployment can be realized. Starting from Release 8 of 3GPP, full coverage of shadow area communication has been achieved using cooperative diversity techniques in LTE-Advanced systems.
In consideration of the superiority of cooperative relay technology, the cooperative relay technology is increasingly applied to the security field to realize confidential transmission of information. On the other hand, with the widespread use of smart phones and tablet computers, the limited operating life of mobile devices is one of the most critical issues affecting the user experience due to the limited battery capacity, and for this reason, radio frequency power supply technologies based on energy harvesting technologies have received extensive attention and extensive research. Radio frequency energy harvesting technology can invisibly provide permanent energy to mobile devices, and eliminates the need for a power grid into which a battery is plugged for charging. Aiming at the problems, the safety problem of the physical layer in the wireless energy supply cooperative relay network is deeply researched, and a safe transmission method which is more in line with the actual transmission scene is provided.
Disclosure of Invention
The invention aims to overcome the defects of the existing physical layer safe transmission method under the relay network with limited energy and provides a safe transmission method of a bidirectional wireless power supply relay system. Compared with the traditional transmission mode, the invention can effectively improve the security performance of transmission.
The invention is realized by adopting the following technical scheme:
a safe transmission method of a bidirectional wireless power supply relay system comprises the following steps:
1) in a charging stage, both an information source and a target node send energy signals to an untrusted relay node with limited energy in a network according to a set power coefficient, the relay node obtains energy from the energy signals, and meanwhile, the relay node obtains channel information of a related channel;
2) in the information source broadcasting stage, the information source broadcasts a signal to be transmitted into a communication network by using the rest power, and in order to ensure the reliability of communication, a target node broadcasts an interference signal into the network by using the rest power;
3) a relay forwarding stage: the relay node calculates the optimal beam vector by using the acquired channel information, and forwards a weighted information to the destination node, thereby improving the security performance of transmission.
The further improvement of the invention is that the implementation method of the step 1) is as follows:
in a charging stage, a relay node acquires channel state information of nodes in a network; the method comprises the steps that a relay and an information source are provided, channel gains of the relay and a destination node are respectively expressed as f and g, charging time is theta T, wherein theta represents a charging time distribution coefficient, and T represents the length of the whole communication time slot; setting a communication network to comprise an information source node S, a destination node D and N untrusted relay nodes; and has flFor channel state information between the l-th relay node and the source, glFor the channel state information of the l-th relay node to the destination node, niIs complex Gaussian noise at the receiver end of node i, and ni～CN(0,N0) (ii) a Therefore, the l-th relay RlThe received energy signal is:
Figure BDA0001571444110000031
wherein, 1 is less than or equal tol≤N，PsIs the total power of the source, p1Distribution coefficient, x, of charging power for the source1Is an energy signal transmitted by a source, and E { | x1|2}＝1，PdIs the total power of the destination node, p2Distribution coefficient of charging power to destination node, x2Is an energy signal transmitted by the destination node, and E { | x2|2}＝1。
The further improvement of the invention is that the implementation method of the step 2) is as follows:
in the information source broadcasting stage, the information source broadcasts a useful signal by using the power left in the previous stage, and meanwhile, in order to ensure the communication safety, the destination node broadcasts and transmits an interference signal by using the power left in the previous stage, the duration of the stage is (1-theta) T/2, and the power coefficient of the information source in the stage is (1-rho)1) The power coefficient of the destination node is (1-rho)2) (ii) a In the source broadcasting stage, the l-th relay RlThe received signal is represented as:
Figure BDA0001571444110000032
wherein x issRepresents information symbols to be transmitted, and E { | xs|2}＝1，xjRepresents an interference signal, and E { | xj|2}＝1；
Untrusted relay RlSignal-to-noise ratio gamma of terminalleIs represented as follows:
Figure BDA0001571444110000033
wherein the content of the first and second substances,
Figure BDA0001571444110000034
therefore, the eavesdropping SNR γeComprises the following steps:
Figure BDA0001571444110000035
the expression of the signal-to-noise ratio w of the eavesdropping terminal is as follows:
Figure BDA0001571444110000041
the cumulative distribution function of w is therefore expressed as:
Figure BDA0001571444110000042
the probability density function for w is expressed as:
Figure BDA0001571444110000043
order to
Figure BDA0001571444110000044
F is thenWThe form of (w) is simplified as:
Figure BDA0001571444110000045
order to
Figure BDA0001571444110000047
F is thenW(w)＝g(w)-h(w)；
The expected E w for the eavesdropping signal-to-noise ratio w is expressed in the form:
Figure BDA0001571444110000048
order to
Figure BDA0001571444110000049
Then E { w } ═ I1-I2；
The following solutions are given to1、I2：
Figure BDA0001571444110000051
Order to
Figure BDA0001571444110000052
Then
Figure BDA0001571444110000053
Following solution I3：
Figure BDA0001571444110000054
Further obtain I1Expression (c):
Figure BDA0001571444110000055
in order to ensure that the water-soluble organic acid,
Figure BDA0001571444110000056
then
Figure BDA0001571444110000057
Following solution I4：
Figure BDA0001571444110000058
Further obtain I2Finally, the expression is expressed by the expression E { w } ═ I1-I2And obtaining a closed expression of E { w }.
The further improvement of the invention is that the implementation method of the step 3) is as follows:
in a relay forwarding stage, a relay node calculates an optimal beam vector and forwards a useful signal according to the obtained channel information of a related channel by taking the signal-to-noise ratio of a maximized destination end as a target so as to improve the confidentiality of a system, wherein the duration of the stage is (1-theta) T/2;
in the relay forwarding stage, the transmission signal of the ith relay is written as:
xl＝wlβlyl
wherein, wlDenotes the forwarding coefficient, betalNormalized power factor, representing the l-th relay, is expressed as:
Figure BDA0001571444110000061
further, the signal after the destination node cancels the interference is expressed as:
Figure BDA0001571444110000062
signal-to-noise ratio gamma of destination nodedIs represented as follows:
Figure BDA0001571444110000063
wherein the content of the first and second substances,
Figure BDA0001571444110000064
A＝dia g{β1g1,β2g2,…,βNgN},
Figure BDA0001571444110000065
the near-optimal beamforming vector is:
Figure BDA0001571444110000066
wherein the content of the first and second substances,the instantaneous capacity of the destination node is thus written as:
in the formula:
Figure BDA0001571444110000069
wherein the content of the first and second substances,
Figure BDA00015714441100000610
η represents energy conversion efficiency;
according to classical Kolmogorov law of great numbers, gamma1d,γ2d,…,γNdFor independent and identically distributed random variables, then
Figure BDA00015714441100000611
Thus, when the number of relays is greater than 10, the approximate traversal capacity of the destination node is expressed as:
Figure BDA0001571444110000078
the above formula shows that if the approximate capacity of the destination is calculated, gamma is calculated first1d,γ2d,…,γNdThe mean value of (a); due to gamma1d,γ2d,…,γNdIs independent and uniformly distributed random variable, and does not lose generality, so that gamma is calculatedldThe desired μ of;
the process of solving μ is as follows:
μ＝E{γld}
wherein, γldSplit into two parts gammald1And gammald2，γld1And gammald2In the form of:
Figure BDA0001571444110000071
Figure BDA0001571444110000072
therefore, solving for μ further translates to:
μ＝E{γld}
＝E{γld1}+E{γld2}
the following solutions to γld1And gammald2The expectation of (2):
to simplify the expression, the following variable substitutions are made:
order to
Figure BDA0001571444110000079
C2＝2ρ1θηρs,C3＝2ρ2θηρd|gl|2|gl|2,C4＝(1-θ)(1-ρ1)ρs,C5＝(1-θ)(1-ρ2)ρd,C6＝2ρ2(1-ρ1)θηρsρd
Channel gain | fl|2,|gl|2Are all subject to an exponential distribution, i.e. | fl|2～exp(λ1)，|gl|2～exp(λ2) Here, the
Figure BDA0001571444110000073
Figure BDA0001571444110000074
WhereinRespectively representing signals fl、glThe variance of (a);
to facilitate the derivation of the formula, let X ═ fl|2,Y＝|gl|2Then the desired solution is expressed as follows:
Figure BDA0001571444110000076
order toThen
Figure BDA0001571444110000081
Wherein
Figure BDA0001571444110000082
Ei (x) in the above formula represents an exponential integration function, which is defined as
Figure BDA0001571444110000083
Therefore, the first and second electrodes are formed on the substrate,
Figure BDA0001571444110000084
therefore, it is not only easy to use
Figure BDA0001571444110000085
Order to
Figure BDA0001571444110000087
Then E { gamma }ld1}＝-λ1λ2C1E2-λ1λ2C1E3+λ1λ2C1E4
The following solutions respectively for E2、E3、E4Expression (c):
Figure BDA0001571444110000091
order to
Figure BDA0001571444110000092
Then
Figure BDA0001571444110000093
The following solutions respectively for E31、E32：
Figure BDA0001571444110000094
In the above formula
Figure BDA0001571444110000095
Therefore, it is not only easy to use
Figure BDA0001571444110000096
Figure BDA0001571444110000097
In the above formula
Figure BDA0001571444110000098
Therefore, it is not only easy to use
Figure BDA0001571444110000099
Then can solve E3The expression of (1);
Figure BDA00015714441100000910
in the above formula
Figure BDA0001571444110000101
Therefore, it is not only easy to use
Figure BDA0001571444110000102
In conclusion, gamma is obtainedld1(iii) a desire;
solving for γld2The expectation of (2):
Figure BDA0001571444110000103
order to
In the above formula
Figure BDA0001571444110000105
So as to obtain Q1The expression of (a) is as follows:
Figure BDA0001571444110000106
thus obtaining E { gammald2The expression of is as follows:
Figure BDA0001571444110000107
as a variable substitution, order
Figure BDA0001571444110000108
Figure BDA0001571444110000111
Then E { gamma }ld2}＝λ1λ2C6Q2+λ1λ2C6Q3；
Q will be solved separately as follows2，Q3：
Figure BDA0001571444110000112
Figure BDA0001571444110000113
In the above formula
Therefore, it is not only easy to use
Figure BDA0001571444110000115
In conclusion, an approximate average capacity expression of a legal user side is obtained; and the traversal privacy capacity is mathematically approximated as follows:
Figure BDA0001571444110000116
a further improvement of the present invention is that, since the average security capacity of the system is closely related to the power allocation coefficients of the source and destination nodes, the algorithm for the power allocation coefficient that maximizes the average security capacity of the system is represented as follows:
1. initializing power distribution coefficients rho of source and destination nodes1,ρ2；
2. Obtaining the final power distribution coefficient rho of the source node and the destination node through one-dimensional search algorithm iteration1,ρ2The method comprises the following specific steps:
2.1 setting initial step length of search to tau0＝0.1，ρi(0)＝0，i＝1,2；
2.2 when ρi(k+1)＝ρi(k)+τ0When k is more than or equal to 0 and less than or equal to 9, circulating until the average security capacity C of the systems(ρi(k+1))≤Cs(ρi(k) And C) and Cs(ρi(k-1))≤Cs(ρi(k) Go to step 2.5; otherwise, entering the next cycle;
2.3 setting the step length of the search algorithm as tau1＝0.01，ρi(0)＝ρi(k)；
2.4, when ρi(n+1)＝ρi(n)+τ1，0≤n≤9, circulate until Cs(ρi(n+1))≤Cs(ρi(n)) and Cs(ρi(n-1))≤Cs(ρi(n)), and proceeds to the next step;
2.5 Power distribution factor to maximize privacy Capacity
Figure BDA0001571444110000121
Updating power distribution coefficient rho of source node and destination node at the same time1,ρ2。
The invention has the following beneficial technical effects:
firstly, the invention can ensure that the relay node obtains energy forwarding information in a mode of joint power supply of the information source and the target node in a charging stage under the condition that the energy of the relay node is limited, further ensure the communication safety in a mode of cooperative interference of the target node in an information source broadcasting stage, and finally ensure that the relay node obtains the optimal weight coefficient through beam design in a relay forwarding stage, thereby improving the overall confidentiality. Finally, the invention provides a distributed power allocation algorithm that maximizes the average privacy capacity of the system.
Drawings
FIG. 1 is a flow chart of a wireless power supply-based physical layer secure transmission method according to the present invention;
FIG. 2 is a block diagram of a transmission model of the overall system of the present invention;
FIG. 3 is a diagram of a single transmission block model according to the present invention;
FIG. 4 is a model diagram of a simulation scenario;
FIG. 5 shows the power distribution coefficient of the source node for the average privacy capacity vs of the system;
fig. 6 shows the power distribution coefficient of the destination node of the average privacy capacity vs of the system.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
It is assumed that the communication network comprises a source node S, a destination node D and N relay nodes. f. oflFor the l-th relayChannel state information between a node and a source node, glFor the channel state information from the l-th relay node to the destination, niIs complex Gaussian noise at the receiver end of node i, and ni～CN(0,N0)。
Referring to fig. 1 to fig. 3, the method for securely transmitting a bidirectional wireless power supply relay system provided by the present invention includes the following steps:
1) in a charging stage, both a source node and a destination node send energy signals to an untrusted relay node with limited energy in a network according to a set power coefficient, the relay node obtains energy from the energy signals, and meanwhile, the relay node obtains channel information of a related channel;
in a charging stage, a relay node acquires channel state information of nodes in a network; the channel gains of the relay and the destination node are respectively expressed as f and g, the charging time is theta T, wherein theta represents a charging time distribution coefficient, T represents the length of the whole communication time slot, and the charging power distribution coefficient of the information source is rho1The charging power distribution coefficient of the destination node is rho2(ii) a Setting a communication network to comprise an information source node S, a destination node D and N untrusted relay nodes; and has flFor channel state information between the l-th relay node and the source, glFor the channel state information from the l-th relay node to the destination, niIs complex Gaussian noise at the receiver end of node i, and ni～CN(0,N0) (ii) a Therefore, the l-th relay R in step 1)lThe received energy signal is:
Figure BDA0001571444110000131
wherein l is more than or equal to 1 and less than or equal to N, PsIs the total power of the source, p1Distribution coefficient, x, of charging power for the source1Is an energy signal transmitted by a source, and E { | x1|2}＝1，PdIs the total power of the destination node, p2Distribution coefficient of charging power to destination node, x2Is an energy signal transmitted by the destination node, and E { | x2|2}＝1。
2) In the information source broadcasting stage, the information source broadcasts a signal to be transmitted into a communication network by using the rest power, in order to ensure the reliability of communication, a destination node simultaneously broadcasts an interference signal into the network by using the rest power, and because an interference sample is known at a receiving end, the interference sample can be completely eliminated when being finally received;
in the source broadcasting stage, the source broadcasts a useful signal by using the power left in the previous stage, and in order to ensure the communication safety, the destination node broadcasts and transmits an interference signal by using the power left in the previous stage, the duration of the stage is (1-theta) T/2, and the power coefficient of the source in the stage is (1-rho)1) The power coefficient of the destination node is (1-rho)2). In the source broadcasting stage, the l-th relay RlThe received signal may be expressed as:
Figure BDA0001571444110000141
wherein x issRepresents information symbols to be transmitted, and E { | xs|2}＝1，xjRepresents an interference signal, and E { | xj|2}＝1。
Untrusted relay RlSignal-to-noise ratio gamma of terminalleCan be expressed as follows:
Figure BDA0001571444110000142
wherein the content of the first and second substances,
therefore, the eavesdropping SNR γeComprises the following steps:
the expression of the signal-to-noise ratio w of the eavesdropping terminal is as follows:
Figure BDA0001571444110000145
the Cumulative Distribution Function (CDF) of w can be expressed as:
the Probability Density Function (PDF) of w can be expressed as:
Figure BDA0001571444110000147
order to
Figure BDA0001571444110000148
F is thenWThe form of (w) can be simplified as:
Figure BDA0001571444110000149
order to
Figure BDA0001571444110000151
Figure BDA0001571444110000152
F is thenW(w)＝g(w)-h(w)；
The expected E w for the eavesdropping signal-to-noise ratio w can be expressed in the form:
Figure BDA0001571444110000153
order to
Figure BDA0001571444110000154
Then E { w } ═ I1-I2。
Next, the solution I will be separately solved1、I2：
Figure BDA0001571444110000155
Order to
Figure BDA0001571444110000156
Then
Figure BDA0001571444110000157
The solution I will be described below3：
Further, I can be obtained1Expression (c):
Figure BDA0001571444110000159
order toThen
Figure BDA00015714441100001511
The solution I will be described below4：
Further, I can be obtained2May be finally expressed by the expression E { w } ═ I1-I2And obtaining a closed expression of E { w }.
3) A relay forwarding stage: the relay node calculates the optimal beam vector by using the acquired channel information, and forwards a weighted information to the destination node, thereby further improving the security performance of transmission.
And in the relay forwarding stage, the relay node calculates an optimal beam vector and forwards a useful signal according to the obtained channel information of the related channel by taking the signal-to-noise ratio of a destination end as a target so as to improve the confidentiality of the system, wherein the duration of the stage is (1-theta) T/2.
In the relay forwarding stage, the transmission signal of the ith relay can be written as:
xl＝wlβlyl
wherein, wlDenotes the forwarding coefficient, betalThe normalized power factor, which represents the ith relay, can be expressed as:
Figure BDA0001571444110000162
further, the signal after the destination node cancels the interference may be represented as:
Figure BDA0001571444110000163
signal-to-noise ratio gamma of destination nodedCan be expressed as follows:
Figure BDA0001571444110000164
whereinA＝dia g{β1g1,β2g2,…,βNgN},
Figure BDA0001571444110000166
The invention aims to maximize the signal-to-noise ratio of a target end, to maximize the secrecy capacity of a system as much as possible, and to take the signal-to-noise ratio of the target end into consideration in the form of Rayleigh quotient, so that the conclusion in related documents can be directly utilized to obtain a near-optimal beam forming vector as follows:
Figure BDA0001571444110000171
wherein the content of the first and second substances,
Figure BDA0001571444110000172
the instantaneous capacity of the destination can thus be written as:
Figure BDA0001571444110000173
in the formula:
Figure BDA0001571444110000174
wherein the content of the first and second substances,
Figure BDA0001571444110000175
η represents energy conversion efficiency.
According to classical Kolmogorov law of great numbers, gamma1d,γ2d,…,γNdFor independent and identically distributed random variables, then
Figure BDA0001571444110000176
Thus, when the number of relays is greater than 10, the approximate traversal capacity of the destination node can be expressed as:
Figure BDA0001571444110000177
the above equation shows that to calculate the approximate capacity of the destination, γ must be calculated first1d,γ2d,…,γNdIs measured. Due to gamma1d,γ2d,…,γNdIs independent and uniformly distributed random variable, and has no loss of generality as long as gamma is calculatedldThe desired μmay be.
The process of solving μ is as follows:
μ＝E{γld}
wherein, γldCan be decomposed into two parts of gammald1And gammald2，γld1And gammald2In the form of:
Figure BDA0001571444110000178
Figure BDA0001571444110000179
therefore, solving for μ can be further translated into:
μ＝E{γld}
＝E{γld1}+E{γld2}
the following will solve for γ separatelyld1And gammald2Is expected to
To simplify the expression, the following variable substitutions were made:
order toC2＝2ρ1θηρs,C3＝2ρ2θηρd|gl|2|gl|2,C4＝(1-θ)(1-ρ1)ρs,C5＝(1-θ)(1-ρ2)ρd,C6＝2ρ2(1-ρ1)θηρsρd
Channel gain | fl|2,|gl|2Are all subject to an exponential distribution, i.e. | fl|2～exp(λ1)，|gl|2～exp(λ2) Here, the
Figure BDA0001571444110000182
Figure BDA0001571444110000183
Wherein
Figure BDA0001571444110000184
Respectively representing signals fl、glThe variance of (c).
To facilitate the derivation of the formula, let X ═ fl|2,Y＝|gl|2The desired solution can then be expressedThe following were used:
Figure BDA0001571444110000185
order to
Figure BDA0001571444110000186
Then
Wherein
Figure BDA0001571444110000188
Ei (x) in the above formula represents an exponential integration function, which is defined as
Figure BDA0001571444110000189
Therefore, the first and second electrodes are formed on the substrate,
Figure BDA0001571444110000191
therefore, it is not only easy to use
Figure BDA0001571444110000192
Order to
Figure BDA0001571444110000193
Figure BDA0001571444110000194
Then E { gamma }ld1}＝-λ1λ2C1E2-λ1λ2C1E3+λ1λ2C1E4。
The following solutions respectively for E2、E3、E4Expression ofFormula (II):
Figure BDA0001571444110000195
Figure BDA0001571444110000196
order toThen
Figure BDA0001571444110000198
The following solutions respectively for E31、E32：
Figure BDA0001571444110000199
In the above formula
Figure BDA0001571444110000201
Therefore, it is not only easy to use
Figure BDA0001571444110000203
In the above formula
Figure BDA0001571444110000204
Therefore, it is not only easy to use
Figure BDA0001571444110000205
Then can solve E3Is described in (1).
In the above formula
Figure BDA0001571444110000207
Therefore, it is not only easy to use
In summary, γ can be obtainedld1Expectation of (2), solving for γld2The expectation is that.
Figure BDA0001571444110000209
Order to
Figure BDA0001571444110000211
In the above formula
Figure BDA0001571444110000212
So that Q can be obtained1The expression of (a) is as follows:
so that E { gamma } can be obtainedld2The expression of is as follows:
Figure BDA0001571444110000214
as a variable substitution, order
Figure BDA0001571444110000215
Figure BDA0001571444110000216
Then E { gamma }ld2}＝λ1λ2C6Q2+λ1λ2C6Q3。
Q will be solved separately as follows2，Q3。
Figure BDA0001571444110000218
In the above formula
Figure BDA0001571444110000219
Therefore, it is not only easy to use
Figure BDA0001571444110000221
In summary, an approximate average capacity expression of the legitimate ue can be obtained. In summary, the traversal privacy capabilities of the system can be mathematically approximated as follows:
Figure BDA0001571444110000226
the algorithm for finding the power distribution coefficient that maximizes the average secret capacity of the system can be expressed as follows:
1. initializing power distribution coefficients rho of source and destination nodes1,ρ2；
2. Obtaining the final power distribution coefficient rho of the source node and the destination node through one-dimensional search algorithm iteration1,ρ2The method comprises the following specific steps:
2.1 setting initial step length of search to tau0＝0.1，ρi(0)＝0，i＝1,2；
2.2 when ρi(k+1)＝ρi(k)+τ0When k is more than or equal to 0 and less than or equal to 9, circulating until the average security capacity C of the systems(ρi(k+1))≤Cs(ρi(k) And C) and Cs(ρi(k-1))≤Cs(ρi(k) Go to step 2.5; otherwise, entering the next cycle;
2.3 setting search AlgorithmIs defined as τ1＝0.01，ρi(0)＝ρi(k)；
2.4, when ρi(n+1)＝ρi(n)+τ1When n is more than or equal to 0 and less than or equal to 9, circulating until Cs(ρi(n+1))≤Cs(ρi(n)) and Cs(ρi(n-1))≤Cs(ρi(n)), and proceeds to the next step;
2.5 Power distribution factor to maximize privacy CapacityUpdating power distribution coefficient rho of source node and destination node simultaneously1,ρ2。
Simulation experiment and effect analysis
The simulation model parameters are as follows: total number of relays N is 20, total transmission power of source Ps10W, total transmission power P of destinationd10W, receiver noise power N 01 mW. Channel coefficient
Figure BDA0001571444110000224
Including path loss and small-scale fading, K0＝1,α＝2,dijIs the distance between node i and node j. For convenience, the transmission block time length T is 1.
The performance curve of the average privacy capacity proposed by the present invention is simulated according to the above parameter settings, and it can be seen from fig. 5 that under the condition of fixing the destination power distribution coefficient, the optimal source power distribution coefficient exists to maximize the average privacy capacity of the system, and the two curves in the figure also illustrate the accuracy of the theoretical approximation result. As can be seen from fig. 6, when the source-side power distribution coefficient is fixed, there is also an optimal destination node power distribution coefficient to maximize the average privacy capacity of the system. The physical layer secret transmission method based on wireless energy supply can ensure that the system achieves certain safety performance.

Claims (4)

1. A safe transmission method of a bidirectional wireless power supply relay system is characterized by comprising the following steps:
1) in a charging stage, both an information source and a target node send energy signals to an untrusted relay node with limited energy in a network according to a set power coefficient, the relay node obtains energy from the energy signals, and meanwhile, the relay node obtains channel information of a related channel; the specific implementation method comprises the following steps:
in a charging stage, a relay node acquires channel state information of nodes in a network; the method comprises the steps that a relay and an information source are provided, channel gains of the relay and a destination node are respectively expressed as f and g, charging time is theta T, wherein theta represents a charging time distribution coefficient, and T represents the length of the whole communication time slot; setting a communication network to comprise an information source node S, a destination node D and N untrusted relay nodes; and has flFor channel state information between the l-th relay node and the source, glFor the channel state information of the l-th relay node to the destination node, niIs complex Gaussian noise at the receiver end of node i, and ni～CN(0,N0)，N0Is the receiver noise power; therefore, the l-th relay RlThe received energy signal is:
wherein l is more than or equal to 1 and less than or equal to N, PsIs the total power of the source, p1Distribution coefficient, x, of charging power for the source1Is an energy signal transmitted by a source, and E { | x1|2}＝1，PdIs the total power of the destination node, p2Distribution coefficient of charging power to destination node, x2Is an energy signal transmitted by the destination node, and E { | x2|2}＝1；
2) In the information source broadcasting stage, the information source broadcasts a signal to be transmitted into a communication network by using the rest power, and in order to ensure the reliability of communication, a target node broadcasts an interference signal into the network by using the rest power;
3) a relay forwarding stage: the relay node calculates the optimal beam vector by using the acquired channel information, and forwards a weighted information to the destination node, thereby improving the security performance of transmission.
2. The method for safely transmitting the bidirectional wireless power supply relay system according to claim 1, wherein the step 2) is realized by the following steps:
in the information source broadcasting stage, the information source broadcasts a useful signal by using the power left in the previous stage, and meanwhile, in order to ensure the communication safety, the destination node broadcasts and transmits an interference signal by using the power left in the previous stage, the duration of the stage is (1-theta) T/2, and the power coefficient of the information source in the stage is (1-rho)1) The power coefficient of the destination node is (1-rho)2) (ii) a In the source broadcasting stage, the l-th relay RlThe received signal is represented as:
Figure FDA0002218927220000021
wherein x issRepresents information symbols to be transmitted, and E { | xs|2}＝1，xjRepresents an interference signal, and E { | xj|2}＝1；
Untrusted relay RlSignal-to-noise ratio gamma of terminalleIs represented as follows:
Figure FDA0002218927220000022
wherein the content of the first and second substances,
Figure FDA0002218927220000023
therefore, the eavesdropping SNR γeComprises the following steps:
Figure FDA0002218927220000024
the expression of the signal-to-noise ratio w of the eavesdropping terminal is as follows:
Figure FDA0002218927220000025
because, | fl|2And | gl|2All obedience parameter is lambda1And λ2So the cumulative distribution function of w is expressed as:
Figure FDA0002218927220000026
the probability density function for w is expressed as:
Figure FDA0002218927220000027
order to
Figure FDA0002218927220000028
F is thenWThe form of (w) is simplified as:
Figure FDA0002218927220000029
order to
Figure FDA0002218927220000032
F is thenW(w)＝g(w)-h(w)；
The expected E w for the eavesdropping signal-to-noise ratio w is expressed in the form:
Figure FDA0002218927220000033
order to
Figure FDA0002218927220000034
Then E { w } ═ I1-I2；
The following solutions are given to1、I2：
Figure FDA0002218927220000035
Order to
Figure FDA0002218927220000036
Then
Figure FDA0002218927220000037
Following solution I3：
Figure FDA0002218927220000038
Wherein, Wa,b(x) Is the Whittaker function;
further obtain I1The expression of (1);
Figure FDA0002218927220000039
in order to ensure that the water-soluble organic acid,
Figure FDA00022189272200000310
then
Figure FDA00022189272200000311
Following solution I4：
Figure FDA0002218927220000041
Further obtain I2Finally, the expression is expressed by the expression E { w } ═ I1-I2And obtaining a closed expression of E { w }.
3. The safe transmission method of the bidirectional wireless power supply relay system according to claim 2, wherein the step 3) is realized by the following steps:
in a relay forwarding stage, a relay node calculates an optimal beam vector and forwards a useful signal according to the obtained channel information of a related channel by taking the signal-to-noise ratio of a maximized destination end as a target so as to improve the confidentiality of a system, wherein the duration of the stage is (1-theta) T/2;
in the relay forwarding stage, the transmission signal of the ith relay is written as:
xl＝wlβlyl
wherein, wlDenotes the forwarding coefficient, betalNormalized power factor, representing the l-th relay, is expressed as:
further, the signal after the destination node cancels the interference is expressed as:
Figure FDA0002218927220000043
wherein the content of the first and second substances,
Figure FDA0002218927220000044
eta represents energy conversion efficiency, ndIs the receiver noise;
signal-to-noise ratio gamma of destination nodedIs represented as follows:
Figure FDA0002218927220000045
wherein the content of the first and second substances,A＝diag{β1g1,β2g2,…,βNgN},
Figure FDA0002218927220000047
the near-optimal beamforming vector is:
Figure FDA0002218927220000051
wherein the content of the first and second substances,
Figure FDA0002218927220000052
the instantaneous capacity of the destination node is thus written as:
Figure FDA0002218927220000053
in the formula:
wherein the content of the first and second substances,
Figure FDA0002218927220000055
according to classical Kolmogorov law of great numbers, gamma1d,γ2d,…,γNdFor independent and identically distributed random variables, then
Figure FDA0002218927220000056
Thus, when the number of relays is greater than 10, the approximate traversal capacity of the destination node is expressed as:
Figure FDA0002218927220000059
the above formula shows that if the approximate capacity of the destination is calculated, gamma is calculated first1d,γ2d,…,γNdThe mean value of (a); due to gamma1d,γ2d,…,γNdIs independent and uniformly distributed random variable, and does not lose generality, so that gamma is calculatedldThe desired μ of;
the process of solving μ is as follows:
μ＝E{γld}
wherein, γldSplit into two parts gammald1And gammald2，γld1And gammald2In the form of:
Figure FDA0002218927220000057
Figure FDA0002218927220000058
therefore, solving for μ further translates to:
μ＝E{γld}
＝E{γld1}+E{γld2}
the following solutions to γld1And gammald2The expectation of (2):
to simplify the expression, the following variable substitutions are made:
order toC2＝2ρ1θηρs，C3＝2ρ2θηρd，C4＝(1-θ)(1-ρ1)ρs，C5＝(1-θ)(1-ρ2)ρd， C6＝2ρ2(1-ρ1)θηρsρd
Channel gain | fl|2,|gl|2Are all subject to an exponential distribution, i.e. | fl|2～exp(λ1)，|gl|2～exp(λ2) Here, the
Figure FDA0002218927220000062
Figure FDA0002218927220000063
Wherein
Figure FDA0002218927220000064
Respectively representing signals fl、glThe variance of (a);
to facilitate the derivation of the formula, let x ═ fl|2,y＝|gl|2Then the desired solution is expressed as follows:
Figure FDA0002218927220000065
order toThen
Figure FDA0002218927220000067
Wherein
Figure FDA0002218927220000068
Ei (x) in the above formula represents an exponential integration function, which is defined as
Figure FDA0002218927220000069
Therefore, the first and second electrodes are formed on the substrate,
Figure FDA0002218927220000071
therefore, it is not only easy to use
Figure FDA0002218927220000072
Order to
Figure FDA0002218927220000079
Figure FDA0002218927220000073
Then E { gamma }ld1}＝-λ1λ2C1E2-λ1λ2C1E3+λ1λ2C1E4
The following solutions respectively for E2、E3、E4Expression (c):
Figure FDA0002218927220000075
order to
Figure FDA0002218927220000076
Then
Figure FDA0002218927220000077
The following solutions respectively for E31、E32：
Figure FDA0002218927220000078
In the above formula
Figure FDA0002218927220000081
Therefore, it is not only easy to use
Figure FDA0002218927220000082
Figure FDA0002218927220000083
Wherein Γ (x) is a Gamma function;
in the above formula
Figure FDA0002218927220000084
Therefore, it is not only easy to useThen can solve E3The expression of (1);
Figure FDA0002218927220000086
in the above formula
Figure FDA0002218927220000087
Therefore, it is not only easy to use
In conclusion, gamma is obtainedld1(iii) a desire;
solving for γld2The expectation of (2):
order to
In the above formula
Figure FDA0002218927220000093
So as to obtain Q1The expression of (a) is as follows:
Figure FDA0002218927220000094
thus obtaining E { gammald2The expression of is as follows:
Figure FDA0002218927220000095
as a variable substitution, order
Figure FDA0002218927220000096
Figure FDA0002218927220000097
Then E { gamma }ld2}＝λ1λ2C6Q2+λ1λ2C6Q3；
Q will be solved separately as follows2，Q3：
Figure FDA0002218927220000098
Figure FDA0002218927220000101
In the above formula
Figure FDA0002218927220000102
Therefore, it is not only easy to use
Figure FDA0002218927220000103
In conclusion, an approximate average capacity expression of a legal user side is obtained; the traversal privacy capacity is thus mathematically represented approximately as follows:
Figure FDA0002218927220000104
4. a method as claimed in claim 2 or 3, wherein the algorithm of the power distribution coefficient for maximizing the average secret capacity of the system is represented as follows:
1. initializing power distribution coefficients rho of source and destination nodes1,ρ2；
2. Obtaining the final power distribution coefficient rho of the source node and the destination node through one-dimensional search algorithm iteration1,ρ2The method comprises the following specific steps:
2.1 setting initial step length of search to tau0＝0.1，ρi(0)＝0，i＝1,2；
2.2 when ρi(k+1)＝ρi(k)+τ0When k is more than or equal to 0 and less than or equal to 9, circulating until the average security capacity C of the systems(ρi(k+1))≤Cs(ρi(k) And C) and Cs(ρi(k-1))≤Cs(ρi(k) Go to step 2.5; otherwise, entering the next cycle;
2.3 setting the step length of the search algorithm as tau1＝0.01，ρi(0)＝ρi(k)；
2.4, when ρi(n+1)＝ρi(n)+τ1When n is more than or equal to 0 and less than or equal to 9, circulating until Cs(ρi(n+1))≤Cs(ρi(n)) and Cs(ρi(n-1))≤Cs(ρi(n)), and proceeds to the next step;
2.5 Power distribution factor to maximize privacy Capacity
Figure FDA0002218927220000105
Updating power distribution coefficient rho of source node and destination node simultaneously1,ρ2。
CN201810118747.5A 2018-02-06 2018-02-06 Safe transmission method of bidirectional wireless power supply relay system Expired - Fee Related CN108418651B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201810118747.5A CN108418651B (en) 2018-02-06 2018-02-06 Safe transmission method of bidirectional wireless power supply relay system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201810118747.5A CN108418651B (en) 2018-02-06 2018-02-06 Safe transmission method of bidirectional wireless power supply relay system

Publications (2)

Publication Number Publication Date
CN108418651A CN108418651A (en) 2018-08-17
CN108418651B true CN108418651B (en) 2020-01-10

Family

ID=63126885

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201810118747.5A Expired - Fee Related CN108418651B (en) 2018-02-06 2018-02-06 Safe transmission method of bidirectional wireless power supply relay system

Country Status (1)

Country Link
CN (1) CN108418651B (en)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109195167B (en) * 2018-09-28 2020-12-18 深圳大学 Method and system for defending jamming attack of wireless energy transmission communication network
CN110086521B (en) * 2019-04-28 2021-11-02 东华大学 Energy acquisition method based on multi-antenna amplification forwarding wireless relay communication system
CN110351885B (en) * 2019-06-29 2020-10-30 中国人民解放军军事科学院国防科技创新研究院 Wireless distributed cooperative network opportunistic channel access method based on threshold measurement

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7684337B2 (en) * 2006-01-17 2010-03-23 Mitsubishi Electric Research Laboratories, Inc. Method and system for communicating in cooperative relay networks
CN104378757A (en) * 2014-12-10 2015-02-25 山东大学 Method for guaranteeing physical layer security in multi-relay multi-interference wiretapping network
CN106911420A (en) * 2017-03-15 2017-06-30 中国人民解放军理工大学 A kind of RF energy gathers the safe transmission method of many relay systems of untrusted
CN107404743A (en) * 2017-04-01 2017-11-28 华侨大学 Time-division energy acquisition based on purpose user scrambling relays safe transmission scheme

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7684337B2 (en) * 2006-01-17 2010-03-23 Mitsubishi Electric Research Laboratories, Inc. Method and system for communicating in cooperative relay networks
CN104378757A (en) * 2014-12-10 2015-02-25 山东大学 Method for guaranteeing physical layer security in multi-relay multi-interference wiretapping network
CN106911420A (en) * 2017-03-15 2017-06-30 中国人民解放军理工大学 A kind of RF energy gathers the safe transmission method of many relay systems of untrusted
CN107404743A (en) * 2017-04-01 2017-11-28 华侨大学 Time-division energy acquisition based on purpose user scrambling relays safe transmission scheme

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
"Private Network Forming Routing Protocol for Adhoc Networks";U.B. Nagesh;《2016 IEEE 6th International Conference on Advanced Computing (IACC)》;20160818;第635-637页 *
"基于迫零中继和广义差分调制的双向TDBC中继网络";蒋煜等;《通信技术》;20170331;第464-468页 *

Also Published As

Publication number Publication date
CN108418651A (en) 2018-08-17

Similar Documents

Publication Publication Date Title
CN109743729B (en) Secret transmission method of wireless energy-carrying cooperative system
Zhu et al. Secure transmission in multicell massive MIMO systems
Zhu et al. Wireless information and power transfer in relay systems with multiple antennas and interference
Ding et al. A general relaying transmission protocol for MIMO secrecy communications
Lee et al. Deep learning based transmit power control in underlaid device-to-device communication
Serafimovski et al. Dual-hop spatial modulation (Dh-SM)
Jameel et al. Secrecy analysis and learning-based optimization of cooperative NOMA SWIPT systems
CN108418651B (en) Safe transmission method of bidirectional wireless power supply relay system
Li et al. Optimal transmit beamforming for secure SWIPT in a two-tier HetNet
Kader et al. Cooperative spectrum sharing with energy harvesting best secondary user selection and non-orthogonal multiple access
Amarasuriya et al. Multi-way amplify-and-forward relay networks with massive MIMO
CN114598397B (en) Energy collection based relay hybrid RF/FSO system and method in eavesdropping environment
Su et al. Secure cooperative transmission in cognitive AF relay systems with destination-aided jamming and energy harvesting
CN110650480B (en) Wireless network relay and interference node selection method facing safe communication
Dang et al. Throughput optimization for noma energy harvesting cognitive radio with multi-UAV-assisted relaying under security constraints
Du et al. Distortion minimization in wireless sensor networks with energy harvesting
Diao et al. Secure wireless-powered NOMA communications in multi-UAV systems
Ma et al. Performance analysis and optimization in two-way cooperative NOMA under two-phase transmission protocol
Kader Interference aided cooperative SWIPT for cellular IoT networks towards 5G and beyond
CN107154818A (en) Co-channel full duplex bi-directional relaying transmission method while based on single carrier frequency domain equalization
Rauniyar et al. Secrecy performance analysis of cooperative nonorthogonal multiple access in IoT networks
CN113726396B (en) High-energy-efficiency confidential transmission method of full-duplex wireless energy-carrying relay communication system
Liu et al. Physical layer security of full-duplex two-way AF relaying networks with optimal relay selection
Yang et al. Performance analysis of secure communication in massive MIMO with imperfect channel state information
Xu et al. Two-plus-one cognitive cooperation based on energy harvesting and spatial multiplexing

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant
CF01 Termination of patent right due to non-payment of annual fee
CF01 Termination of patent right due to non-payment of annual fee

Granted publication date: 20200110