CN110247691A - A kind of safe transmission method for downlink NOMA visible light communication network - Google Patents

A kind of safe transmission method for downlink NOMA visible light communication network Download PDF

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CN110247691A
CN110247691A CN201910514780.4A CN201910514780A CN110247691A CN 110247691 A CN110247691 A CN 110247691A CN 201910514780 A CN201910514780 A CN 201910514780A CN 110247691 A CN110247691 A CN 110247691A
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legitimate user
signal
indicate
constraint
convex
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杜淳
马帅
唐一潇
张凡
李世银
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China University of Mining and Technology CUMT
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China University of Mining and Technology CUMT
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
    • H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
    • H04B10/114—Indoor or close-range type systems
    • H04B10/116—Visible light communication
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0617—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal for beam forming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842—Weighted combining
    • H04B7/086—Weighted combining using weights depending on external parameters, e.g. direction of arrival [DOA], predetermined weights or beamforming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W12/00—Security arrangements; Authentication; Protecting privacy or anonymity
    • H04W12/009—Security arrangements; Authentication; Protecting privacy or anonymity specially adapted for networks, e.g. wireless sensor networks, ad-hoc networks, RFID networks or cloud networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/02—Arrangements for optimising operational condition

Abstract

The invention discloses a kind of safe transmission methods for being used for downlink NOMA (non-orthogonal multiple) visible light communication network, The present invention gives the external world in the safe capacity region with closed expression and interior boundaries, Beam-former is devised for total emission power minimization problem, while meeting QoS of customer (QoS) demand and safe rate constrains, by brightness adjustment control light emitting diode (light emitting diode) total emission power is minimized.For the nonconvex property solved the problems, such as, a kind of relaxation and constrained procedure are proposed.In addition, under the constraint of brightness adjustment control and QoS of customer, using loose and constrained procedure, non-convex problem being converted to quasi- convex formula aiming at the problem that maximizing minimum safe rate, and solved using binary search algorithm, obtaining Wave beam forming scheme.

Description

A kind of safe transmission method for downlink NOMA visible light communication network
Technical field
The invention belongs to visible light communication field more particularly to a kind of safety for downlink NOMA visible light communication network Transmission method.
Background technique
With the explosive growth of wireless data traffic, radio communication occurs that spectral bandwidth is crowded, and network capacity is limited The problem of.Although millimetre-wave attenuator provides the several hundred megahertzs of bandwidth for arriving several gigahertzs, still it is not able to satisfy following wireless The demand of communication.Visible light communication uses light emitting diode, while providing wireless communication and illumination.In order to preferably support to be mostly used Family guarantees the fairness of visible light communication network, non-orthogonal multiple (non-orthogonal multiple access, NOMA (non-orthogonal multiple)) it is a kind of up-and-coming multiple access access strategy.NOMA (non-orthogonal multiple) can significantly improve network The fairness of performance and user performs better than in high s/n ratio scene.And since high s/n ratio scene is in visible light communication network It is very common in network, so NOMA (non-orthogonal multiple) is highly suitable for visible light communication network.
Compared with traditional Radio-Frequency Wireless Communication, it is seen that optic communication has the advantage that
(1) visible light spectrum is resourceful, possesses the broadband of 430THz-790THz, is nearly 10,000 times of wireless frequency spectrum, It can solve the problem of radio communication frequency spectrum resource scarcity；
(2) visible light communication uses common light emitting diode, low in energy consumption, can provide wireless communication and illumination simultaneously, be A kind of typical low-power consumption green communications technology；
(3) visible light communication is without electromagnetic interference, thus can be used for the secure communication in electromagnetic susceptibility region, such as coal mine, The places such as hospital and aircraft；
The technical characterstic of non-orthogonal multiple (NOMA):
(1) receiving end uses serial interference elimination (SIC) technology, the performance of receiver can be improved, basic thought is to adopt With the strategy for eliminating interference step by step, user is made decisions in receiving signal one by one, after carrying out amplitude recovery, which is believed Number multi-access inference generated is subtracted from receiving in signal, and is made decisions again to remaining user, circulate operation, until eliminating All multi-access inferences；
(2) transmitting terminal uses power sharing technology, different power is distributed unused user, to improve gulping down for system The amount of spitting.On the other hand, NOMA (non-orthogonal multiple) is superimposed multiple users in power domain, and in receiving end, receiver can be according to not The different user of same power distinction；
(3) user feedback channel state information is not depended on, field feedback can not depended on using NOMA technology and obtained Stable performance gain, to obtain better performance under the scene of high-speed mobile；
The major Safety of visible light communication is public domain, as library, market, meeting room passive wiretapping. Different from traditional encryption method, safety of physical layer is ensured between the signal-to-noise ratio received based on legitimate user and eavesdropping side The safe transmission of difference.In recent years, researcher's concern uses the safety of physical layer problem of the network of NOMA (non-orthogonal multiple), Have studied the safety and rate maximization problems of single-input single-output NOMA (non-orthogonal multiple) network；Multiple input single output scene In multiple-input and multiple-output scene, central user is legitimate user, and Cell Edge User is that the NOMA of listener-in is (nonopiate more Location) network safe rate maximization problems.
At present, it is not yet clear that the secrecy ability of NOMA (non-orthogonal multiple) visible light communication network and accessible safety speed Rate, and the two indexs are to measure the key index of NOMA (non-orthogonal multiple) visible light communication network safety of physical layer.
Summary of the invention
In view of the deficiencies of the prior art, the present invention provides one kind to be used for downlink NOMA (non-orthogonal multiple) visible light communication The safe transmission method of network, includes the following steps:
Step 1, in downlink transmission process, it is seen that optical communication network uses NOMA (non-orthogonal multiple) scheme, sets kth The transmission signal of a legitimate user is sk, the transmitting signal of light emitting diode is x；
Step 2, the signal y that k-th of legitimate user receives is respectively obtainedkThe signal y received with listener-in EveE；
Step 3, using serial interference elimination (SIC, Successive Interference Cancellation) method, K-th of legitimate user is decoded and removes interferenceObtain the remaining reception signal of k-th of legitimate user
Step 4, the achievable rate upper bound that k-th of legitimate user decodes i-th of legitimate user's signal is solvedListener-in Eve decodes the achievable rate lower bound of i-th of legitimate user's signalAnd then obtain the outer of visible light network security transmission rate Boundary: Indicate that i-th of legitimate user transmits signal siSafe capacity；
Step 5, the achievable rate lower bound that k-th of legitimate user decodes i-th of legitimate user's signal is solvedListener-in Eve decodes the achievable rate upper bound of i-th of legitimate user's signalAnd then obtain the interior of visible light network security transmission rate Boundary:
Step 6, meeting QoS of customer (Quality of Service, QoS) constraint, safe rate constraint, hair While optical diode power constraint, the Wave beam forming design for minimizing total transmission power is obtained, beamformer output forms vector {wk}；
Step 7, meeting the same of the power constraint of QoS of customer constraint, brightness adjustment control and each light emitting diode When, obtain the Wave beam forming design for maximizing the minimum safe rate of NOMA (non-orthogonal multiple) visible optical-fiber network, beamformer output Form vector { wk}。
In step 1, in order to guarantee to transmit the nonnegativity of signal, Wave beam forming vector wkMeet following condition:
Wherein,wk,nIt is the weighting coefficient of k-th of legitimate user Yu n-th of light emitting diode,Table Show the set of light emitting diode, AkFor the amplitude peak and A of source signalk> 0,
W is enabled to indicate Wave beam forming vector, the transmission signal s of k-th of legitimate userkWave beam forming vector be Indicate that N-dimensional real number space, the signal x of light emitting diode transmitting are shown below:
Wherein,It is to guarantee to transmit the non-negative direct current biasing vector of signal, and b >=0,
The transmission power P of light emitting diodeeAre as follows:
Wherein,To average, εkFor target average electrical power,
The instantaneous optical power of light emitting diodeAre as follows:
Average light powerAre as follows:
In addition, visible light communication network will meet light modulation constraint, while meeting eye-safe and actual illumination constraint, kth The transmission signal s of a legitimate userkWave beam forming vector wkAlso to meet following condition:
Wherein, enBe nth elements be 1, other elements be 0 vector；IHIt is the maximum current of light emitting diode,
Define dimming level τ:And 0 τ≤1 <.
Wherein, PTIt is maximum luminous power.
Step 2 includes: to be shone model according to lambert, channel gain of k-th of legitimate user to n-th of light emitting diode gk,nIt indicates are as follows:
Wherein, cos () is cosine function, | | it is modulus, m indicates Lambert emission grade, Log () is logarithmic function, and φ indicates the angle of departure of light emitting diode, φ1/2Indicate the half of half-power angle, ARIt indicates to receive Physical area is held,Wherein nrIndicate the refractive index of receiving end collector lens, APDIndicate Photoelectric Detection The area of device, sin () are SIN function, dk,nIndicate distance of n-th of light emitting diode to k-th of legitimate user, ψkIt indicates The incidence angle of receiving end, ψFOVIndicate the field angle of legitimate user.
In step 2, the signal y that k-th of legitimate user receives is respectively obtainedkThe signal y received with listener-in EveE, It respectively indicates are as follows:
Wherein, siIt is the transmission signal of j-th of legitimate user, wjBe j-th legitimate user transmit the Wave beam forming of signal to Amount, gk=[gk,1,...,gk,N]TIt is the channel vector indicated between light emitting diode and k-th of legitimate user, gE= [gE,1,...,gE,N]TIndicate the channel vector between light emitting diode and listener-in Eve, gE,NIndicate listener-in Eve to n-th The channel gain of light emitting diode；nkIt is the Gaussian noise that k-th of legitimate user receives, mean value 0, variance isnE For the Gaussian noise that listener-in Eve is received, mean value 0, variance is
In step 3, setting channel vector is obeyed:Using serial interference elimination Method decodes k-th of legitimate user and removes interferenceObtain the remaining reception signal of k-th of legitimate userIt indicates are as follows:
In step 4, i-th of legitimate user transmits signal siSafe capacityIt indicates are as follows:
Wherein, pi(si) indicate siDistribution,It indicatesThe upper bound, i.e. k-th legitimate user decode i-th Legitimate user transmits information siRateThe upper bound, 1≤i≤k≤K,Indicate I (si；yE) lower bound, i.e. listener-in Eve decodes i-th of legitimate user and transmits information siRate I (si；yE) lower bound,It respectively indicates are as follows:
Wherein, wjIndicate that j-th of legitimate user transmits signal sjWhen Wave beam forming vector, parameter alpham,γm
It is ABG (Alpha-Beta-Gamma) distribution parameter of corresponding m-th of legitimate user, parameter alphan,γn
It is ABG (Alpha-Beta-Gamma) distribution parameter of corresponding n-th of legitimate user, εm,εnIt is m-th respectively Legitimate user corresponds to the average electrical power of the average electrical power transmitting terminal corresponding with n-th of legitimate user of transmitting terminal；
Wherein, parameter alphaj,γj,εjFor following solution of equations:
Wherein, βjIt is the parameter of ABG distribution, π is pi, and e is natural logrithm, functionErf () is Gauss error function, Γk,iIt is instruction letter Number,
In step 4, i-th of legitimate user transmits signal siSafe capacityThe upper bound are as follows:
WithThe external world for indicating the safe capacity region of NOMA (non-orthogonal multiple) visible optical-fiber network, is given by:
In steps of 5, i-th of legitimate user transmits signal siSafe capacityLower bound indicates are as follows:
Wherein,It indicatesLower bound, i.e. k-th legitimate user decode i-th of legitimate user and transmit information si RateLower bound, 1≤i≤k≤K,Indicate I (si；yE) the upper bound, i.e. listener-in Eve decode i-th of legal use Transmit information s in familyiRate I (si；yE) upper bound,It respectively indicates are as follows:
WithThe interior boundary for indicating the safe capacity region of NOMA (non-orthogonal multiple) visible optical-fiber network, is given by:
In step 6, meeting the same of QoS of customer constraint, safe rate constraint and LED power constraint When, optimize Wave beam forming, minimize total emission power, obtain following optimization problem:
s.t.Rk,i≥ri,1≤i≤k≤K,
Wherein, riIt is decoded information siQoS (service quality) demand, Rk,iIt is legal i-th of k-th of legitimate user's decoding User transmits information siRate,It is information siMinimum safe rate.
Non-convex constraint in solve the above-mentioned problems, first introduces auxiliary variable:
Wherein,Gk,i、Di、an、ck,iIt is auxiliary variable, 1NIt is the column vector of N × 1, all members Element is all 1, eiIt is the unit vector that i-th of element is 1；To which the above problem is converted to following optimization problem:
Using Semidefinite Programming (Semi-definite Programming, SDP) technical treatment, define:W is intermediate variable, loses the constraint that order is 1, problem is converted to:
Wherein, Tr () is the mark for seeking matrix, ck,iBe introduce auxiliary variable, the above problem be still it is non-convex, in order to Problem is converted into correspondingly convex formula, introduces following auxiliary parameter:
Wherein, xk,i, xi, yk,i, yiIt is slack variable, and 1≤i≤k≤K, according to the variable of above-mentioned introducing, problem turns It changes into:
Wherein, anIt is auxiliary variable, in order to which the non-convex constraints conversion in above-mentioned optimization problem at convex constraint, is based on Taylor Series expansion:Non-convex constraint is linearized, whereinX, axIt is intermediate variable, obtains It arrives:
To be approximately its convex formula above-mentioned non-convex problem:
For given auxiliary parameterThe above problem be it is convex, effectively solved using the convex solver of standard, Beamformer output forms vector { wk}。
In step 7, meeting the same of the power constraint of QoS of customer constraint, brightness adjustment control and each light emitting diode When, the minimum safe rate to maximize NOMA (non-orthogonal multiple) visible light communication network is formed as the visible light beam of target Design, obtains following problem:
s.t.Rk,i≥ri,1≤i≤k≤K,
Wherein, PtotalIt is maximum total transmitter power (dBm), using relaxation method, introduces slack variable rsWithIt uses Semidefinite decoding technology rewrites the above problem as follows:
For the non-convex constraint in processing problem, it is defined as follows slack variable:
Non-convex constraint is still had in slack variable, but can be obtained by taylor series expansion approximation corresponding convex Former problem is constrained to following form by form:
Now, former problem becomes quasi- convex problem, and for given rs> 0 be it is convex, therefore, dichotomy can be used The optimal beam forming device of problem is obtained, in given rsUnder the premise of > 0, it can be obtained by handling a series of convex feasibility problems To the more details of optimal beam forming device, optimization problem is as follows:
find{W,{xk,i},{xi},{yk,i},{yi}}
Finally, calculating the optimal solution of the optimization problem by using the binary search of proposition, specifically include as follows Step:
Upper bound r is arranged in step a1u, lower bound rl, optimal solution ropt∈[rl,ru], assigned error εe> 0, if k=0；
Step a2 repeats step a3-a6, until meeting condition: ru-rl≤εe, obtain optimal solution ropt=rk, beamformer output Form vector { wk}；
Step a3, k ← k+1；
Step a4, rk=rl+ru/2；
Step a5, Xie Suoshu optimization problem；
Step a6, if the optimization problem is feasible, assignment: rl=rk；Otherwise, assignment: ru=rk。
For the performance of the safety of physical layer in visible light communication network application NOMA (non-orthogonal multiple) scheme, the present invention Provide the external world and interior boundary in the safe capacity region with closed expression.
For the total emission power minimization problem in downlink NOMA (non-orthogonal multiple) visible light communication network, the present invention Beam-former is designed, while meeting QoS of customer (QoS) requirement and safe rate constraint, is made by brightness adjustment control Total emission power is obtained to minimize.
For the maximization minimum safe problem rate in downlink NOMA (non-orthogonal multiple) visible light communication network, this hair It is bright brightness adjustment control, user QoS constraint under develop Beamforming Method so that minimum safe rate maximize.
The present invention relates to the safe transmission methods of downlink NOMA (non-orthogonal multiple) visible light communication network.The present invention utilizes Information theory, signal processing and convex optimization method provide the external world and interior boundary in the safe capacity region with closed expression.This hair Bright design Beam-former minimizes to handle the total emission power in downlink NOMA (non-orthogonal multiple) visible light communication network Problem and minimum safe rate maximization problems.
The utility model has the advantages that The present invention gives the external world in the safe capacity region with closed expression and interior boundaries, for hair Firing association's minimum power problem devises Beam-former, is meeting QoS of customer (QoS) demand and safe rate constraint While, by brightness adjustment control light emitting diode total emission power is minimized.For the nonconvex property solved the problems, such as, propose A kind of relaxation and constrained procedure.In addition, aiming at the problem that maximizing minimum safe rate, in brightness adjustment control and QoS of customer Constraint under, using loose and constrained procedure, non-convex problem is converted to quasi- convex formula, and asked using binary search algorithm Solution, obtains Wave beam forming scheme.
Detailed description of the invention
The present invention is done with reference to the accompanying drawings and detailed description and is further illustrated, it is of the invention above-mentioned or Otherwise advantage will become apparent.
Fig. 1 is the system model of downlink NOMA (non-orthogonal multiple) visible light communication network.
Fig. 2 is downlink NOMA (non-orthogonal multiple) visible light communication network emulation experiment --- the Nei Jie of safe capacity and outer Boundary.
Fig. 3 is that downlink NOMA (non-orthogonal multiple) visible light communication network minimizes total emission power Beamforming Method stream Cheng Tu.
Fig. 4 is that downlink NOMA (non-orthogonal multiple) visible light communication network maximizes minimum safe rate Beamforming Method Flow chart.
Fig. 5 is downlink NOMA (non-orthogonal multiple) visible light communication network safe transmission emulation experiment --- transmitting total work Rate-targeted rate change curve.
Fig. 6 is downlink NOMA (non-orthogonal multiple) visible light communication network safe transmission emulation experiment --- minimum safe speed Rate-targeted rate change curve.
Specific embodiment
The present invention will be further described with reference to the accompanying drawings and embodiments.
The present invention utilizes letter for the safety of physical layer problem in downlink NOMA (non-orthogonal multiple) visible light communication network Breath opinion, signal processing and convex optimization method, give the interior boundary and the external world in the safe capacity region with closed expression, and Beam-former is developed for total emission power minimization problem and maximization minimum safe problem rate, can be realized transmitting The maximization of the minimum or minimum safe rate of general power.
Fig. 3 is that downlink NOMA (non-orthogonal multiple) visible light communication network minimizes total emission power Beamforming Method stream Cheng Tu, it is seen that optical network system model is as shown in Figure 1, the specific steps are as follows:
Step 1, system relevant parameter and input signal are arranged according to design requirement.
Legitimate user's quantity: K；Listener-in's quantity: 1；
Light emitting diode quantity in each transmitting terminal: N；
For k-th of legitimate user, it is s that direct current biasing transmitting signal is not addedk, parameter is as follows:
Input signal peak value: | sk|≤Ak,
Input signal mean value:
Input signal mean-square value:
Direct current biasing:
Emit signal:
Step 2: setting channel parameter.The channel gain of k-th of legitimate user to n-th of light emitting diode indicates are as follows:
Wherein, cos () is cosine function, | | it is modulus, m indicates Lambert emission grade,For logarithmic function, φ indicates the angle of departure of light emitting diode, φ1/2Indicate half-power angle Half, ARIndicate receiving end physical area,Wherein nrIndicate the refractive index of receiving end collector lens, APDIndicate that the area of photoelectric detector, sin () are SIN function, dk,nIndicate n-th of light emitting diode to k-th of legal use The distance at family, ψkIndicate the incidence angle of receiving end, ψFOVIndicate the field angle of legitimate user.
Step 3, ABG (Alpha-Beta-Gamma) Parameter Relation of legitimate user is solved:
Wherein, βjFor ABG distribution parameter, π is pi, and e is natural logrithm, functionX∈[-Aj,Aj], erf () is Gauss error function, Γk,iIt is indicator function,
Step 4: while meeting QoS of customer constraint, safe rate constraint and LED power constraint, Optimize Wave beam forming, minimize total emission power, solve following optimization problem, obtains beamforming matrix:
s.t.Rk,i≥ri,1≤i≤k≤K,
Wherein, εkIt is input signal mean-square value, wkIt is the beamforming vectors that k-th of legitimate user transmits signal, riIt is solution Code information siQoS (service quality) demand, RiIt is transmission information siMinimum safe rate, ri secIt is safe rate constraint, Ak It is input signal peak value, enIt is the unit vector that nth elements are 1, min { b, IH- b } be the power of each light emitting diode about The combination of beam and brightness adjustment control.
Fig. 4 shows maximization minimum safe rate wave beam shape in downlink NOMA (non-orthogonal multiple) visible light communication network At method, it is seen that optical network system model is as shown in Figure 1, the specific steps are as follows:
Step 1, system relevant parameter and input signal are arranged according to design requirement.
Legitimate user's quantity: K；Listener-in's quantity: 1；
Light emitting diode quantity in each transmitting terminal: N；
For k-th of legitimate user, it is s that direct current biasing transmitting signal is not addedk, parameter is as follows:
Input signal peak value: | sk|≤Ak,
Input signal mean value:
Input signal mean-square value:
Direct current biasing:
Emit signal:
Step 2: setting channel parameter.The channel gain of k-th of legitimate user to n-th of light emitting diode indicates are as follows:
Wherein, cos () is cosine function, | | it is modulus, m indicates Lambert emission grade, Log () is logarithmic function, and φ indicates the angle of departure of light emitting diode, φ1/2Indicate the half of half-power angle, ARIt indicates to receive Physical area is held,Wherein nrIndicate the refractive index of receiving end collector lens, APDIndicate Photoelectric Detection The area of device, sin () are SIN function, dk,nIndicate distance of n-th of light emitting diode to k-th of legitimate user, ψkIt indicates The incidence angle of receiving end, ψFOVIndicate the field angle of legitimate user.
Step 3: solve ABG (Alpha-Beta-Gamma) Parameter Relation of user:
Wherein, βjFor ABG distribution parameter, π is pi, and e is natural logrithm, functionX∈[-Aj,Aj], erf () is Gauss error function, Γk,iIt is indicator function,
Step 4: establishing Optimized model, meeting QoS of customer constraint, brightness adjustment control and each light emitting diode While power constraint, to maximize the minimum safe rate of downlink NOMA (non-orthogonal multiple) visible light communication network as target Wave beam forming design, solve following optimization problem, obtain beamforming matrix:
s.t.Rk,i≥ri,1≤i≤k≤K,
Wherein, εkIt is input signal mean-square value, wkIt is the beamforming vectors that k-th of legitimate user transmits signal, Ptotal It is total emission power, wk,nIt is the weighting coefficient of k-th of legitimate user Yu n-th of light emitting diode, AkIt is input signal peak value, min{b,IH- b } be each light emitting diode power constraint and the combination of brightness adjustment control.
The above problem is converted, the optimal solution of the above problem is calculated using the binary search of proposition.
Binary search:
(1) upper bound r is setu, lower bound rl, optimal solution ropt∈[rl,ru], assigned error εe> 0, if k=0；
(2) step (3)-step (6) are repeated；
(3)k←k+1；
(4)rk=rl+ru/2；
(5) optimization problem of step 7 is solved；
(6) if above-mentioned optimization problem is feasible, assignment: rl=rk；Otherwise, assignment: ru=rk；
(7) until meeting condition: ru-rl≤εe, obtain optimal solution ropt=rk。
In order to assess the external world and interior boundary in the safe capacity region that the present invention provides, emulation setting parameter is as follows: K=2, g1 =1,
Fig. 2 shows the interior boundary and the external world of the safe lane capacity region of the visible optical-fiber network of NOMA (non-orthogonal multiple), this When SNR=10dB,
It can be seen that downlink NOMA (non-orthogonal multiple) proposed by the present invention from Fig. 5 and simulation result shown in fig. 6 Minimizing total emission power Beamforming Method in optical communication network and maximizing minimum safe rate Beamforming Method is It is feasible.(figure Chinese and English is explained as follows: Electrical power: electrical power, Rateth reshold: targeted rate, Secrecy Rate: safe rate, Bit/sec/HZ: bits per second per Hertz, dBm: decibel milliwatt)
Setting in visible light communication network includes three legitimate user Bobs (K=3) and a listener-in Eve, there is 9 hairs Optical diode (N=9), using room as a three-dimensional system of coordinate, origin of one of corner as rectangular coordinate system in space (0,0,0)。
Table 1: the position coordinates (unit: m) of light emitting diode
Table 2: the basic parameter of visible light communication system
LED light lamp shines half-angle φ1/2 60°
The angle of half field-of view of photodetector ψ1 90°
Area photodetector AR 1cm2
Electro-optical efficiency ηc 0.54
Photoelectric conversion efficiency ηl 1
Average electrical noise power σ2 -98.82dBm
Table 3: the position of legitimate user Bob and listener-in Eve
Safe transmission method the present invention provides one kind for downlink NOMA (non-orthogonal multiple) visible light communication network, There are many method and the approach for implementing the technical solution, the above is only a preferred embodiment of the present invention, it is noted that For those skilled in the art, without departing from the principle of the present invention, several change can also be made Into and retouching, these modifications and embellishments should also be considered as the scope of protection of the present invention.Each component part being not known in the present embodiment The available prior art is realized.

Claims (10)

1. a kind of safe transmission method for downlink NOMA visible light communication network, which comprises the steps of:
Step 1, in downlink transmission process, it is seen that optical communication network uses NOMA scheme, sets the transmission of k-th of legitimate user Signal is sk, the transmitting signal of light emitting diode is x；
Step 2, the signal y that k-th of legitimate user receives is respectively obtainedkThe signal y received with listener-in EveE；
Step 3, using method for eliminating serial interference, k-th of legitimate user is decoded and removes interferenceIt obtains k-th The remaining reception signal of legitimate user
Step 4, the achievable rate upper bound that k-th of legitimate user decodes i-th of legitimate user's signal is solvedListener-in Eve is translated The achievable rate lower bound of i-th of legitimate user's signal of codeAnd then obtain the external world of visible light network security transmission rate: Indicate that i-th of legitimate user transmits signal siSafe capacity；
Step 5, the achievable rate lower bound that k-th of legitimate user decodes i-th of legitimate user's signal is solvedListener-in Eve is translated The achievable rate upper bound of i-th of legitimate user's signal of codeAnd then obtain the interior boundary of visible light network security transmission rate:
Step 6, it while meeting QoS of customer constraint, safe rate constraint, LED power constraint, obtains most The Wave beam forming of smallization total transmission power designs, and beamformer output forms vector { wk}；
Step 7, while meeting the power constraint of QoS of customer constraint, brightness adjustment control and each LED light lamp, Obtain maximizing the Wave beam forming design of the minimum safe rate of the visible optical-fiber network of NOMA, beamformer output forms vector { wk}。
2. the method according to claim 1, wherein in step 1, Wave beam forming vector wkMeet following condition:
Wherein,wk,nIt is the weighting coefficient of k-th of legitimate user Yu n-th of light emitting diode,Indicate hair The set of optical diode, AkFor the amplitude peak and A of source signalk> 0,
W is enabled to indicate Wave beam forming vector, the transmission signal s of k-th of legitimate userkWave beam forming vector be Indicate that the real number space of N-dimensional, the signal x of light emitting diode transmitting are shown below:
Wherein,It is to guarantee to transmit the non-negative direct current biasing vector of signal, and b >=0,
The transmission power P of LED light lampeAre as follows:
Wherein,To average, εkFor target average electrical power,
The instantaneous optical power of light emitting diodeAre as follows:
Average light powerAre as follows:
The transmission signal s of k-th of legitimate userkWave beam forming vector wkAlso to meet following condition:
Wherein, enBe nth elements be 1, other elements be 0 vector；IHIt is the maximum current of light emitting diode, definition light modulation Horizontal τ:And 0 τ≤1 <；
Wherein, PTIt is maximum luminous power.
3. according to the method described in claim 2, k-th legal it is characterized in that, step 2 includes: to be shone model according to lambert Channel gain g of the user to n-th of light emitting diodek,nIt indicates are as follows:
Wherein, cos () is cosine function, | | it is modulus, m indicates Lambert emission grade,log () is logarithmic function, and φ indicates the angle of departure of light emitting diode, φ1/2Indicate the half of half-power angle, ARIndicate receiving end object Area is managed,Wherein nrIndicate the refractive index of receiving end collector lens, APDIndicate photoelectric detector Area, sin () are SIN function, dk,nIndicate distance of n-th of light emitting diode to k-th of legitimate user, ψkIt indicates to receive The incidence angle at end, ψFOVIndicate the field angle of legitimate user.
4. according to the method described in claim 3, it is characterized in that, respectively obtaining k-th of legitimate user in step 2 and receiving Signal ykThe signal y received with listener-in EveE, respectively indicate are as follows:
Wherein, sjIt is the transmission signal of j-th of legitimate user, wjIt is the Wave beam forming vector that j-th of legitimate user transmits signal, gk=[gk,1,...,gk,N]TIt is the channel vector g indicated between light emitting diode and k-th of legitimate userE=[gE,1,..., gE,N]TIndicate the channel vector between light emitting diode and listener-in Eve, gE,NIndicate listener-in Eve to n-th light-emitting diodes The channel gain of pipe；nkIt is the Gaussian noise that k-th of legitimate user receives, mean value 0, variance isnEFor listener-in The Gaussian noise that Eve is received, mean value 0, variance are
5. according to the method described in claim 4, it is characterized in that, in step 3, setting channel vector is obeyed:Using method for eliminating serial interference, k-th of legitimate user is decoded and removed dry It disturbsObtain the remaining reception signal of k-th of legitimate userIt indicates are as follows:
6. according to the method described in claim 5, it is characterized in that, in step 4, i-th of legitimate user transmits signal siPeace Full capacityIt indicates are as follows:
Wherein, pi(si) indicate siDistribution,It indicatesThe upper bound, i.e. k-th legitimate user decode i-th it is legal User transmits information siRateThe upper bound, 1≤i≤k≤K,Indicate I (si；yE) lower bound, i.e. listener-in Eve It decodes i-th of legitimate user and transmits information siRate I (si；yE) lower bound,It respectively indicates are as follows:
Wherein, wjIndicate that j-th of legitimate user transmits signal sjWhen Wave beam forming vector, parameter alpham,γmIt is corresponding m-th The ABG distribution parameter of legitimate user, parameter alphan,γnIt is the ABG distribution parameter of corresponding n-th of legitimate user, εm,εnIt is respectively M-th of legitimate user corresponds to the average electrical power of the average electrical power transmitting terminal corresponding with n-th of legitimate user of transmitting terminal；
Wherein, parameter alphaj,γj,εjFor following solution of equations:
Wherein, βjIt is the parameter of ABG distribution, π is pi, and e is natural logrithm, function
Erf () is Gauss error function, Γk,iIt is indicator function,
7. according to the method described in claim 6, it is characterized in that, in step 4, i-th of legitimate user transmits signal siPeace Full capacityThe upper bound are as follows:
WithThe external world for indicating the safe capacity region of the visible optical-fiber network of NOMA, is given by:
8. the method according to the description of claim 7 is characterized in that in steps of 5, i-th of legitimate user transmits signal siPeace Full capacityLower bound indicates are as follows:
Wherein,It indicatesLower bound, i.e. k-th legitimate user decode i-th of legitimate user's information siRateLower bound, 1≤i≤k≤K,Indicate I (si；yE) the upper bound, i.e. listener-in Eve decode i-th of legitimate user's information siRate I (si；yE) upper bound,It respectively indicates are as follows:
WithThe interior boundary for indicating the safe capacity region of the visible optical-fiber network of NOMA, is given by:
9. according to the method described in claim 8, it is characterized in that, meeting QoS of customer constraint, safety in step 6 While rate constraint and LED power constrain, optimize Wave beam forming, minimizes total emission power, optimized as follows Problem:
s.t.Rk,i≥ri,1≤i≤k≤K,
Wherein, riIt is decoded information siQoS (service quality) demand, Rk,iIt is that k-th of legitimate user decodes i-th with legal family Transmit information siRate,It is information siMinimum safe rate；
Non-convex constraint in solve the above-mentioned problems, first introduces auxiliary variable:
Wherein,Gk,i、Di、an、ck,iIt is auxiliary variable, 1NIt is the column vector of N × 1, all elements are all 1, eiIt is the unit vector that i-th of element is 1, so that the above problem is converted to following optimization problem:
Using Semidefinite Programming technical treatment, define:W is auxiliary variable, loses order For 1 constraint, problem is converted to:
Wherein, Tr () is the mark for seeking matrix, ck,iBe introduce auxiliary variable, the above problem be still it is non-convex, in order to by its It is converted into correspondingly convex formula, introduces following auxiliary parameter:
Wherein, xk,i, xi, yk,i, yiIt is slack variable, also, 1≤i≤k≤K, according to the variable of above-mentioned introducing, problem conversion At:
Wherein, anIt is auxiliary variable, in order to which the non-convex constraints conversion in above-mentioned optimization problem at convex constraint, is based on Taylor series Expansion:Non-convex constraint is linearized, whereinX, axIt is intermediate variable, obtains:
To be approximately its convex formula above-mentioned non-convex problem:
For given auxiliary parameterThe above problem be it is convex, effectively solved using the convex solver of standard, export Wave beam forming vector { wk}。
10. according to the method described in claim 9, it is characterized in that, meeting QoS of customer constraint, light modulation in step 7 While the power constraint of control and each light emitting diode, to maximize the minimum safe rate of NOMA visible light communication network Design is formed for the visible light beam of target, obtains following problem:
s.t.Rk,i≥ri,1≤i≤k≤K,
Wherein, PtotalIt is maximum total transmitter power (dBm), using relaxation method, introduces slack variable rsWithUse semidefinite Relaxing techniques rewrite the above problem as follows:
For the non-convex constraint in processing problem, it is defined as follows slack variable:
Corresponding convex formula is obtained by taylor series expansion approximation, former problem is constrained to following form:
Former problem becomes quasi- convex problem, and for given rs> 0 be it is convex, obtain the optimal beam of problem with dichotomy Shaper, in given rsUnder the premise of > 0, optimization problem is as follows:
find{W,{xk,i},{xi},{yk,i},{yi}}
Finally, calculating the optimal solution of the optimization problem by using the binary search of proposition, specifically comprise the following steps:
Upper bound r is arranged in step a1u, lower bound rl, optimal solution ropt∈[rl,ru], assigned error εe> 0, if k=0；
Step a2 repeats step a3-a6, until meeting condition: ru-rl≤εe, obtain optimal solution ropt=rk, beamformer output formed Vector { wk}；
Step a3, k ← k+1；
Step a4, rk=rl+ru/2；
Step a5, Xie Suoshu optimization problem；
Step a6, if the optimization problem is feasible, assignment: rl=rk；Otherwise, assignment: ru=rk。
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Publication number Priority date Publication date Assignee Title
CN111885732A (en) * 2020-08-06 2020-11-03 桂林电子科技大学 Dynamic resource allocation method for enhancing NOMA visible light communication network security
CN111885732B (en) * 2020-08-06 2021-03-26 桂林电子科技大学 Dynamic resource allocation method for enhancing NOMA visible light communication network security
CN112272183A (en) * 2020-10-29 2021-01-26 桂林电子科技大学 RIS-assisted NOMA (unified messaging architecture) method for enabling VLC (visible light communication)/RF (radio frequency) hybrid network secure transmission
CN112859909A (en) * 2021-01-05 2021-05-28 中国科学院上海微系统与信息技术研究所 Unmanned aerial vehicle auxiliary network data secure transmission method with coexistence of internal and external eavesdropping
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CN114598389A (en) * 2022-03-09 2022-06-07 国网能源研究院有限公司 Visible light information and energy synchronous transmission network and rate maximization method and device
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