CN106911387B - Visible light communication multiple cell interference management method - Google Patents

Abstract

The invention discloses visible light communication multiple cell interference management methods, including a kind of centralized visible light communication multiple cell interference management method and a kind of distributed visible light communication multiple cell interference management method, the present invention relates to visible light communication field interference channel MISO multiple cell visible light interference management frames.The present invention utilizes information theory, signal processing and convex optimization method, proposes centralized and distributed two kinds of interference management frames.Interference management frame proposed by the invention can effectively reduce the interference of minizone, guarantee ownership goal rate, while reducing transmission power, improve efficiency.The present invention proposes to propose targetedly method for different scenes, while method computational accuracy is high, and solving speed is fast, and distributed interference management method can effectively reduce information exchange in system, mitigate network load, these features decrease the energy consumption of system entirety, improve system energy efficiency.

Description

Visible light communication multiple cell interference management method

Technical field

The invention belongs to visible light communication field more particularly to visible light communication multiple cell interference management methods.

Background technique

The research of visible light communication technology has important scientific meaning and application prospect.Visible light communication target be High-speed transfer is carried out on the basis of LED illumination System, it is necessary to first have to guarantee the related request of room lighting.Therefore, with foundation Radio-Frequency Wireless Communication system under the constraint of limited average electrical power is different, it is seen that optic communication is in order to guarantee eye-safe and comfortable Degree requires and brightness of illumination requirement, it is also necessary to meet limited peak power constraint and the constraint of limited average light power, be simultaneously Meet the performance requirement of LED and optical device, limited average electrical power constraint also has certain difference with Radio-Frequency Wireless Communication Place.

Compared with traditional Radio-Frequency Wireless Communication, it is seen that optic communication has the following advantages:

(1) visible light communication frequency spectrum resource is abundant, and frequency range is nearly the one of wireless frequency spectrum between 400THz-800THz Wan Bei can crack electromagnetic spectrum scarcity of resources quagmire；

(2) ballistic device of visible light communication is common LED lamp, and LED light power consumption is only the 20% of conventional incandescent, it is seen that Optic communication belongs to typical low-power consumption green communications technology；

(3) visible light communication has the characteristic of directed radiation, limit its coverage area controllably can, is conducive to construct safe letter Cease space；

(4) visible light communication network will with internet, mobile radio communication and power network depth integration, residential areas of denseness/ It is user's high speed data communication services under the scenes such as Office Area, subway, high-speed rail；

(5) visible light communication can be used for the secure communication in electromagnetic susceptibility region without electromagnetic interference, as coal mine, hospital and The places such as aircraft；

Visible light communication multiple cell interference channel correlative study at present is less, there is no effective visible light communication how small at present Area's interference management method proposes.

Summary of the invention

In actual scene, a LED lamp is usually to be made of multiple LED, therefore, for visible light interference channel net Network can carry out more LED Wave beam forming designs, to reduce the interference between each cell.

It constructs a kind of transmitting signal with maximum entropy distribution first to improve transmission capacity, is then directed to different applications Scene and network size, the present invention propose visible light communication multiple cell interference management method respectively, specifically include a kind of concentration Formula visible light communication multiple cell interference management method and a kind of distributed visible light communication multiple cell interference management method.

Centralized visible light communication multiple cell interference management method is to establish master controller, collects the complete of each transmitting-receiving pair Portion's information optimizes processing, and a kind of centralized visible light communication multiple cell interference management method includes the following steps:

Step 1, for i-th of user in visible light communication network, it is not added the transmitting signal X of direct current biasing_i It is configured；

Step 2, the ABG (Alpha-Beta-Gamma) for solving i-th of user is distributed corresponding probability density function；

Step 3, the transmitting signal X that direct current biasing is not added is calculated_iDifferential entropy { h (X_i)}；

Step 4, it is assumed that comprising K transmission pair in visible light communication network, in each transmission in, transmitting terminal includes N A LED, receiving end only include a photoelectric detector PD (PhotoDetector), solve transmitting signal X_iOptical power and electric work Rate；

Step 5, channel parameter is set；

Step 6, the channel capacity lower bound based on ABG distribution of i-th of user is solved

Step 7, optimal beam forming designs；

Step 8: beamformer output forms matrix { w_i}。

In step 1, the transmitting signal X of direct current biasing is not added_iObey continuous probability distribution, the probability of this probability distribution Density function is f_i(X_i), and probability density function f_i(X_i) meet following condition:

Wherein, A_iFor the amplitude peak and A of source signal_i> 0, then the transmitting signal X of direct current biasing is not added_iAmplitude model Enclose, mean value and average electrical power difference it is as follows:

|X_i|≤A_i,

Wherein ε_iFor the average electrical power of target user i,To average.

In step 2, the ABG of i-th of user is distributed corresponding probability density function f_i ^ABG(X_i) are as follows:

Wherein, K indicates total number of users, i.e., transmission is to sum, parameter alpha_i, β_iAnd γ_iFor following solution of equations:

Wherein π is pi, and e is natural logrithm, functionX∈[-A_i,A_i], Erf () is Gauss error function.

In step 3, the transmitting signal X that direct current biasing is not added is calculated by following formula_iDifferential entropy { h (X_i) }:

Wherein α_iAnd γ_iFor ABG distribution parameter, log₂() is the logarithmic function with 2 for the truth of a matter, and ln () is nature pair Number.

In step 4, for i-th of transmission pair, w is enabled_iIndicate Wave beam forming vector, w_i,nIndicate the weighting coefficient of n-th of LED of i-th of transmission pair, n=1 ..., N,The real number space of expression N-dimensional, i-th Transmitting terminal transmits information X_iTo i-th of receiving end, wherein | X_i|≤A_i,AndK Transmission is indicated to sum, the signal s that i-th of transmitting terminal is emitted_iAre as follows:

Wherein l_iFor the direct current biasing vector of i-th of user,b_iFor i-th user's Direct current biasing size, and b_i>=0, it is necessary for non-negative due to emitting signal in visible light communication, w_iIt must satisfy:

Wherein | | it is modulus,

The resulting transmitting signal s of step 4_iOptical powerAnd electrical powerIt is respectively as follows:

Wherein K indicates transmission to sum, and N indicates that LED sum in each transmitting terminal, i indicate the serial number of transmission pair,N indicates LED serial number in each transmitting terminal,| | | | to seek 2- norm.

Step 5 includes: because the channel gain of usual line-of-sight propagation (LOS) link is much larger than the scattering chain reflected to form Road, it is possible to which the influence for only considering line-of-sight propagation link shines model according to lambert, n-th of LED to i-th on j-th of lamps and lanterns The channel gain g of a user_i,j,_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 LED, φ₁/₂Indicate the half of half-power angle, η_cIndicate electro-optic conversion effect Rate, η_lIndicate photoelectric conversion efficiency, G indicates the gain of trsanscondutance amplifier, A_RIndicate receiving end physical area size,Wherein n_rIndicate receiving end collector lens refractive index, A_PDIndicate the area of photoelectric detector, sin () is SIN function, d_i,j,nIndicate n-th of LED at a distance from i-th of user, ψ_nIndicate the incidence angle of receiving end, ψ_FoVIt indicates The visual field (FoV) width of user.

In step 6, pass through the channel capacity lower bound based on ABG distribution of i-th of user of following equations

Wherein, σ²For noise power, g_i,jFor j-th of transmitting terminal to the channel gain of i-th of user, w_jEmit for j-th The Wave beam forming vector at end.

In step 7, according to convex optimum theory, under each ownership goal rate constraint and each LED power constraint condition, with It minimizes the visible light beam that transmission power is target and forms frame, obtain following formula:

Wherein, s.t. expression suchthat, i.e., " so that ", R_iIt is the targeted rate of i-th of receiving end, e_nFor in addition to i-th Element is 1 and vector that other elements are 0, and min expression is minimized, and s.t. is such that, i.e., " so that "；

But first of above-mentioned optimization problem is constrained to a quadratic constraints, so that this problem is one non-convex secondary It constrains double optimization problem (QCQP), is NP- difficulty problem according to this kind of optimization problems of existing document.

Following optimization problem is converted by above-mentioned formula:

Wherein g_i,jFor j-th of transmitting terminal to the channel gain of i-th of user, K indicates transmission to sum, and N indicates each transmitting LED sum in end,(parameter alpha_j、γ_jUsing solving parameter alpha in step 2_i, β_iAnd γ_iMethod be calculated, The subscript of parameter in equation group is changed to j),And It is handled using semi definite programming technology SDR (Semi-DefiniteRelaxation), definitionSo thatAnd And rank (W_i)=1, above-mentioned optimization problem relaxation are as follows:

Wherein Tr () is the mark for seeking matrix, this problem is convex semi definite programming problem, by up to interior-point algohnhm solution Optimal solution out, i.e.,Minimum value and corresponding w_i。

Centralized visible light communication multiple cell interference management method, it is desirable that carry out data between different LED light and information is total It enjoys, this will lead to a large amount of signaling overheads.In network passback capacity by limited time, this problem will will limit visible light network Using.In order to reduce the expense of data exchange, the invention also discloses a kind of distributed visible light communication multiple cell interference managements Method includes the following steps:

Step 1, for i-th of user in visible light communication network, it is not added the transmitting signal X of direct current biasing_i It is configured；The transmitting signal X of direct current biasing is not added_iObey continuous probability distribution, the probability density letter of this probability distribution Number is f_i(X_i), and probability density function f_i(X_i) meet following condition:

Wherein, A_i> 0 is the amplitude peak of source signal, then the transmitting signal X of direct current biasing is not added_iAmplitude range, Value and average electrical power difference are as follows:

|X_i|≤A_i,

Wherein ε_iFor the average electrical power of target i,To average；

Step 2, the ABG (Alpha-Beta-Gamma) for solving i-th of user is distributed corresponding probability density function:

Wherein, K indicates the quantity of user, parameter alpha_i, β_iAnd γ_iFor following solution of equations:

Wherein π is pi, and e is natural logrithm, functionX∈[-A_i,A_i], Erf () is Gauss error function；

Step 3, the transmitting signal X that direct current biasing is not added is calculated_iDifferential entropy { h (X_i) }:

Wherein α_iAnd γ_iThe ABG distribution parameter solved by equation in step 2, log₂() is the logarithm with 2 for the truth of a matter Function, ln () are natural logrithm；

Step 4, it is assumed that comprising K transmission pair in visible light communication network, in each transmission in, transmitting terminal includes N A LED, receiving end only include a photoelectric detector PD (PhotoDetector), solve transmitting signal X_iOptical power and electric work Rate: for i-th of transmission pair, w is enabled_iIndicate Wave beam forming vector,w_i,nIndicate i-th The weighting coefficient of n-th of LED of a transmission pair, n=1 ..., N,Indicate the real number space of N-dimensional, i-th of transmitting terminal transmission Information X_iTo i-th of receiving end, wherein | X_i|≤A_i,AndI-th of transmitting terminal The signal s emitted_iAre as follows:

Wherein l_iFor the direct current biasing vector of i-th of user,b_iFor i-th user's Direct current biasing size, and b_i>=0, it is necessary for non-negative due to emitting signal in visible light communication, w_iIt must satisfy:

Wherein | | it is modulus,

Emit signal s_iOptical powerAnd electrical powerIt is respectively as follows:

Wherein K indicates transmission to sum, and N indicates that LED sum in each transmitting terminal, i indicate the serial number of transmission pairN indicates LED serial number in each transmitting terminal,| | | | to seek 2- norm；

Step 5, channel parameter is set: being shone model according to lambert, n-th of LED to i-th user on j-th of lamps and lanterns Channel gain g_i,j,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 LED, φ_1/2Indicate the half of half-power angle, η_cIndicate electro-optic conversion effect Rate, η_lIndicate photoelectric conversion efficiency, G indicates the gain of trsanscondutance amplifier, A_RIndicate receiving end physical area size,Wherein n_rIndicate receiving end collector lens refractive index, A_PDIndicate the area of photoelectric detector, sin () is SIN function, d_i,j,nIndicate n-th of LED at a distance from i-th of user, ψ_nIndicate the incidence angle of receiving end, ψ_FoVIt indicates The visual field width of user；

Step 6, centralized optimization problem K distributed subproblem is decomposed into solve；According to change of direction multiplier ADMM (Alternating Direction Method of Multipliers) optimization algorithm, by centralized interference management frame The optimization problem of frame converts are as follows:

Wherein g_i,jFor j-th of transmitting terminal to the channel gain of i-th of user, AndR_iIt is the targeted rate of i-th of user, e_nFor In addition to i-th of element is 1 and vector that other elements are 0, σ²For noise power, w_jFor j-th of transmitting terminal Wave beam forming to Amount, local variable is that local interference information is v_i, v_i=[v_i,1,...,v_i,j,...v_i,K,η_i]^T, j ≠ i, andWherein variable v_i,jTable Show the interference of j-th of LED light to i-th of user；Variable η_iIndicate total interference that i-th of LED light receives, Tr () is to seek square The mark of battle array；

Define global variableThe relationship of local variable and global variable are as follows:

v_i=Z_iv

WhereinReal number space is tieed up for (K+1) × (K+1), the problem after conversion is write a Chinese character in simplified form Are as follows:

Wherein subproblem f_i(v_i) is defined as:

s.t.u_iTr(W_ig_i,ig_i,i ^T)≥η_i+c_i

Simplified problem is a globally consistent problem, i.e., according to constraint condition, local variable v_iIt finally should be with the overall situation Variable v is consistent, is solved using alternating direction multiplier ADMM algorithm, corresponding LagrangianL_ζ({v_i},τ_i, v) are as follows:

Wherein τ_iIt for the Lagrange multiplier with optimization problem constraint link, or is dual variable, ζ is penalty factor；

Step 7, the number of iterations t=0, initializing variable v (0), τ (0) and penalty factor ζ are enabled, ξ > 0 is given precision；

Step 8, local variable { v when t+1 iteration is updated_i(t+1) } subproblem f, is solved_i(v_i) and following K distribution Formula optimization problem:

WhereinExpression makes the smallest value of B, τ in A_i() is dual variable, v_i() is that part becomes Amount；

Step 9, local variable { v when t+1 iteration is exchanged with other LED light_i(t+1)}；

Step 10, the global variable v (t+1) when t+1 iteration is updated, it may be assumed that

WhereinExpression makes the smallest value of B in A；

Step 11, dual variable τ when t+1 iteration is updated_i(t+1), it may be assumed that

τ_i(t+1)=τ_i(t)+ζ(v_i(t+1)-Z_iv(t+1)).

Step 12, whenWhen, terminate iteration；Otherwise, t is updated to t+1, and returned Step 8；

Step 13, beamformer output forms matrix { w_i}。

The present invention relates to visible light communication field interference channel MISO multiple cell visible light interference management frames.Benefit of the invention With information theory, signal processing and convex optimization method, centralized and distributed two kinds of interference management frames are proposed.

The utility model has the advantages that interference management frame proposed by the invention can effectively reduce the interference of minizone, guarantee to use Family targeted rate, while transmission power is reduced, improve efficiency.The present invention proposes to propose targetedly side for different scenes Method, while method computational accuracy is high, solving speed is fast, and distributed interference management method can effectively reduce information in system Exchange, mitigates network load, these features decrease the energy consumption of system entirety, improve system energy efficiency.

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 visible light communication MISO interference channel system model.

Fig. 2 is centralized visible light communication multiple cell interference management method flow chart in specific implementation.

Fig. 3 is distributed visible light communication multiple cell interference management method flow chart in specific implementation.

Fig. 4 is 1 power of distributed visible light communication interference management frame emulation experiment-targeted rate change curve.

Fig. 5 is 2 errors of distributed visible light communication interference management frame emulation experiment-the number of iterations change curve.

Specific embodiment

The present invention will be further described with reference to the accompanying drawings and embodiments.

The present invention proposes two kinds of new frames for visible light interference management frame, using information theory, signal processing and Convex optimization method proposes and meets visible light communication constraint requirements, possesses closed expression and tighter channel capacity calculates Method, the design and calculating of completion visible light interference management and Wave beam forming that can be simple and fast.

Fig. 2 shows the basic flow of the centralized visible light communication multiple cell interference management using technical solution of the present invention Journey, it is seen that light interference channel 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.

For i-th of user, the transmitting signal that direct current biasing is not added is X_i, parameter is as follows:

Peak value: | X_i|≤A_i；

Mean value:

Mean-square value:

Step 2: seek ABG (Alpha-Beta-Gamma) Parameter Relation of each user:

Wherein π is pi, and e is natural logrithm,Erf () is Gauss mistake Difference function.

Obtain corresponding parameter alpha_i, β_iAnd γ_i, calculate the probability density function of the ABG probability distribution of each user:

Step 3: calculating information source differential entropy { h (X_i), i.e.,Wherein ln () is natural logrithm.

Step 4: setting emission parameter.

Transmission is to quantity: K；

LED quantity in each transmitting terminal: N

For i-th,A transmitting terminal,

Input reference signal: | s_i|≤A_i；

Input signal mean value:

Input signal mean-square value:

Direct current biasing:

Emit signal: x_i=w_is_i+b_i,

Step 5: setting channel parameter.The channel gain of n-th of LED to i-th user can be expressed as on j-th of lamps and lanterns

WhereinIndicate Lambert emission grade；φ indicates the angle of departure of LED, φ_1/2Indicate half-power The half at angle；η_cIndicate electro-optical efficiency；η_lIndicate photoelectric conversion efficiency；The gain of G expression trsanscondutance amplifier；A_RExpression connects Receiving end physical area size；d_i,nIndicate n-th of LED at a distance from i-th of user；ψ_nIndicate the incidence angle of receiving end；ψ_FoVTable Show the visual field (FoV) width of user.The definition of receiving end physical area size isWherein n_rExpression connects Receiving end collector lens refractive index, A_PDIndicate the area of photoelectric detector.

Step 6: solve the channel capacity lower bound based on ABG distribution for i-th of user:

Wherein R_iIt is the targeted rate of i-th of receiving end, e_nTo be 1 in addition to i-th of element and vector that other elements are 0. π is pi, σ²For noise power, | | it is modulus, | | | | to seek 2- norm, min is to minimize, α_iAnd γ_iFor ABG Distribution parameter, ε_iFor the average electrical power of corresponding transmitting terminal, g_i,jFor j-th of transmitting terminal to the channel gain of i-th of receiving end, w_j For the Wave beam forming vector of j-th of transmitting terminal, log₂() is the logarithmic function with 2 for the truth of a matter, ε_iFor average electrical power, b_iFor Direct current biasing, A_iFor the amplitude peak of source signal.

Step 7: Wave beam forming optimization problem is solved, wave beam formed matrix is obtained:

WhereinAndπ is pi, σ²For noise power, | | it is modulus, min is to minimize, ε_iFor the average electrical power of corresponding transmitting terminal, g_i,jIt is sent out for j-th Penetrate channel gain of the end to i-th of receiving end, w_jFor the Wave beam forming vector of j-th of transmitting terminal, log₂It is the truth of a matter that (), which is with 2, Logarithmic function, ε_iFor average electrical power, b_iFor direct current biasing, A_iFor the amplitude peak of source signal.

Fig. 3 shows the basic flow of the distributed visible light communication multiple cell interference management using technical solution of the present invention Journey, it is seen that light interference channel 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.

For i-th of user, the transmitting signal that direct current biasing is not added is X_i, parameter is as follows:

Peak value: | X_i|≤A_i；

Mean value:

Mean-square value:

Step 2: seeking the solving equations of each user

Wherein π is pi, and e is natural logrithm,Erf () is Gauss mistake Difference function.

Obtain corresponding parameter alpha_i, β_iAnd γ_i, calculate the probability density function of the ABG probability distribution of each user:

Step 3: calculating information source differential entropy { h (X_i), i.e.,Wherein ln () is natural logrithm.

Step 4: setting emission parameter.

Transmission is to quantity: K；

LED quantity in each transmitting terminal: N

For i-th,A transmitting terminal,

Input reference signal: | s_i|≤A_i；

Input signal mean value:

Input signal mean-square value:

Direct current biasing:

Emit signal: x_i=w_is_i+b_i,

Step 5: setting channel parameter.The channel gain of n-th of LED to i-th user can be expressed as on j-th of lamps and lanterns

WhereinIndicate Lambert emission grade；φ indicates the angle of departure of LED, φ_1/2Indicate half-power The half at angle；η_cIndicate electro-optical efficiency；η_lIndicate photoelectric conversion efficiency；The gain of G expression trsanscondutance amplifier；A_RExpression connects Receiving end physical area size；d_i,nIndicate n-th of LED at a distance from i-th of user；ψ_nIndicate the incidence angle of receiving end；ψ_FoVTable Show the visual field (FoV) width of user.The definition of receiving end physical area size isWherein n_rExpression connects Receiving end collector lens refractive index, A_PDIndicate the area of photoelectric detector.

Step 6: distributed optimization model of the construction based on ADMM algorithm；

Step 7: iterative calculation solves the distributed optimization model of ADMM algorithm, obtains beam forming matrix.

In order to verify effect of the present invention, simulation comparison experiment has been carried out.

For basic visible light interference channel communication system, the calculation formulae for related parameters is as follows:

System average electrical power:

System average light power:

System Normalized Signal/Noise Ratio (dB):

System peak-to-average power ratio:

Given system Signal to Noise Ratio (SNR) and system peak-to-average power ratioIn the case where,

System average electrical power:

System average light power:

For i-th of LED light,

Average electrical power distribution coefficient: v_i,v_i∈[0,1],

Average light power distribution coefficient: μ_i,μ_i∈[0,1],

Average electrical power: ε_i=v_iε；

Average light power: A_i=μ_iA；

Peak-to-average power ratio:

For distributed visible light communication interference management frame, LED light and receiving end position coordinates are as shown in table 1, distribution Formula visible light communication interference management frame emulation experiment experiment 1 illustrates this hair according to the emulation experiment parameter given shown in table 2 Bright technical solution is in varied situations with the general power situation of change that targeted rate changes, distributed visible light communication interference pipe Frame emulation experiment experiment 2 is managed according to the emulation experiment parameter given shown in table 3, technical solution of the present invention is illustrated and is not sympathizing with With the relative error situation of change that the number of iterations changes under condition.Simulation result according to Fig.4, can be seen that the present invention is dry Disturb management method be it is feasible, optimal general power can be solved.Algorithmic statement speed proposed by the present invention as can be seen from Figure 5 It spends quickly, and error can be less than 5%.(figure Chinese and English is explained as follows: ElectricalPower: electrical power, Ratethreshold: targeted rate, RelativePowerError: relative power error, IterationIndex: iteration time Number, Bits/sec/Hz: bits per second per Hertz, dBm: decibel milliwatt)

The calculation formulae for related parameters is as follows:

For basic visible light interference channel communication system, the calculation formulae for related parameters is as follows:

System average electrical power:

System average light power:

System Normalized Signal/Noise Ratio (dB):

System peak-to-average power ratio:

Given system Signal to Noise Ratio (SNR) and system peak-to-average power ratioIn the case where,

System average electrical power:

System average light power:

System gross electric capacity:

For i-th of LED light,

Average electrical power distribution coefficient: v_i,v_i∈[0,1],

Average light power distribution coefficient: μ_i,μ_i∈[0,1],

Average electrical power: ε_i=v_iε；

Average light power: A_i=μ_iA；

Peak-to-average power ratio:

Wherein assume A₁=A₂=A₃=A₄, ε₁=ε₂=ε₃=ε₄And

Assuming that in (20 × 20 × 5m³) visible light communication network network, wherein one, room corner conduct are disposed in room The origin (0,0,0) of rectangular coordinate system in space includes (K=4) a transmission pair in network.In other words, 4 LED are disposed in room Lamp, every lamp is the light emitting array being made of multiple LED, and the center of array is as shown in table 3, and parasang is rice in table.

Table 1:LED lamp and receiving end position coordinates

Table 2: visible light communication interference management frame emulation experiment tests 1 parameter

Table 3: visible light communication interference management frame emulation experiment tests 2 parameters

The present invention provides visible light communication multiple cell interference management methods, implement method and the way of the technical solution There are many diameter, the above is only a preferred embodiment of the present invention, it is noted that for those skilled in the art For, various improvements and modifications may be made without departing from the principle of the present invention, these improvements and modifications should also regard For protection scope of the present invention.All undefined components in this embodiment can be implemented in the prior art.

Claims (2)

1. a kind of centralization visible light communication multiple cell interference management method, includes the following steps:

Step 1, for i-th of user in visible light communication network, it is not added the transmitting signal X of direct current biasing_iIt is set It sets；

Step 2, the ABG for solving i-th of user is distributed corresponding probability density function；

Step 3, the transmitting signal X that direct current biasing is not added is calculated_iDifferential entropy { h (X_i)}；

Step 4, it is assumed that comprising K transmission pair in visible light communication network, in each transmission in, transmitting terminal includes N number of LED, receiving end only include a photoelectric detector PD, solve transmitting signal X_iOptical power and electrical power；

Step 5, channel parameter is set；

Step 6, the channel capacity lower bound based on ABG distribution of i-th of user is solved

Step 7, optimal beam forming designs；

Step 8: beamformer output forms matrix { w_i}；

In step 1, the transmitting signal X of direct current biasing is not added_iObey continuous probability distribution, the probability density of this probability distribution Function is f_i(X_i), and probability density function f_i(X_i) meet following condition:

Wherein, A_iFor the amplitude peak and A of source signal_iThe transmitting signal X of direct current biasing is not added then in > 0_iAmplitude range, Value and average electrical power difference are as follows:

|X_i|≤A_i,

Wherein ε_iThe target average electrical power of the transmitting signal of direct current biasing is not added for i-th of user,To average；

In step 2, the ABG of i-th of user is distributed corresponding probability density function f_i ^ABG(X_i) are as follows:

Wherein, K indicates total number of users, i.e., transmission is to sum, parameter alpha_i, β_iAnd γ_iFor following solution of equations:

Wherein π is pi, and e is natural logrithm, function

In step 3, the transmitting signal X that direct current biasing is not added is calculated by following formula_iDifferential entropy { h (X_i) }:

Wherein log₂() is the logarithmic function with 2 for the truth of a matter, and ln () is natural logrithm；

In step 4, for i-th of transmission pair, w is enabled_iIndicate Wave beam forming vector, w_i,nIndicate the weighting coefficient of n-th of LED of i-th of transmission pair, n=1 ..., N,Indicate the real number space of N-dimensional, wherein | X_i|≤A_i,AndK indicates what transmission emitted sum, i-th of transmitting terminal Signal s_iAre as follows:

Wherein l_iFor the direct current biasing vector of i-th of user,b_iFor the direct current of i-th of user Bias size, and b_i>=0, it is necessary for non-negative due to emitting signal in visible light communication, w_iIt must satisfy:

Wherein | | it is modulus,

The resulting transmitting signal s of step 4_iOptical powerAnd electrical powerIt is respectively as follows:

Wherein i indicates the serial number of transmission pair,N indicates LED serial number in each transmitting terminal,| | | | to seek 2- norm；

Step 5 includes: to be shone model according to lambert, the channel gain g of n-th of LED to i-th user on j-th of lamps and lanterns_i,j,nTable It is shown as:

Wherein, cos () is cosine function, | | it is modulus, m indicates Lambert emission grade,log(·) For logarithmic function, φ indicates the angle of departure of LED, φ_1/2Indicate the half of half-power angle, η_cIndicate electro-optical efficiency, η_lIndicate light Photoelectric transformation efficiency, G indicate the gain of trsanscondutance amplifier, A_RIndicate receiving end physical area size,Its Middle n_rIndicate receiving end collector lens refractive index, A_PDIndicate that the area of photoelectric detector, sin () are SIN function, d_i,j,nTable Show n-th of LED at a distance from i-th of user, ψ_nIndicate the incidence angle of receiving end, ψ_FoVIndicate the visual field width of user；

In step 6, pass through the channel capacity lower bound based on ABG distribution of i-th of user of following equations

Wherein, σ²For noise power, g_i,jFor j-th of transmitting terminal to the channel gain of i-th of user, w_jFor j-th transmitting terminal Wave beam forming vector；ε_jThe target average electrical power of the transmitting signal of direct current biasing is not added for j-th of user；

In step 7, according to convex optimum theory, under each ownership goal rate constraint and each LED power constraint condition, with minimum Change the visible light beam that transmission power is target and form frame, obtains following formula:

Wherein R_iIt is the targeted rate of i-th of user, e_nTo be 1 in addition to i-th of element and vector that other elements are 0, min table Show and minimizes；

Following optimization problem is converted by above-mentioned formula:

Wherein g_i,jFor j-th of transmitting terminal to the channel gain of i-th of user, AndUse semi definite programming technical treatment, definitionSo thatAnd rank (W_i)=1, above-mentioned optimization problem relaxation are as follows:

Wherein g_i,iFor i-th of transmitting terminal to the channel gain of i-th of user, Tr () is the mark for seeking matrix, by up to interior point Algorithm solves optimal solution, i.e.,Minimum value and corresponding w_i。

2. a kind of distribution visible light communication multiple cell interference management method, which comprises the steps of:

Step 1, for i-th of user in visible light communication network, it is not added the transmitting signal X of direct current biasing_iIt is set It sets；The transmitting signal X of direct current biasing is not added_iContinuous probability distribution is obeyed, the probability density function of this probability distribution is f_i (X_i), and probability density function f_i(X_i) meet following condition:

Wherein A_iFor the amplitude peak of source signal, A_iThe transmitting signal X of direct current biasing is not added then in > 0_iAmplitude range, mean value Distinguish with average electrical power as follows:

|X_i|≤A_i,

Wherein ε_iThe average electrical power of the transmitting signal of direct current biasing is not added for i-th of user,To average；

Step 2, the ABG for solving i-th of user is distributed corresponding probability density function:

Wherein K indicates total number of users, i.e., transmission is to sum, parameter alpha_i, β_iAnd γ_iFor following solution of equations:

Wherein π is pi, and e is natural logrithm, functionerf () is Gauss error function；

Step 3, the transmitting signal X that direct current biasing is not added is calculated_iDifferential entropy { h (X_i) }:

Wherein log₂() is the logarithmic function with 2 for the truth of a matter, and ln () is natural logrithm；

Step 4, it is assumed that comprising K transmission pair in visible light communication network, in each transmission in, transmitting terminal includes N number of LED, receiving end only include a photoelectric detector PD, solve transmitting signal X_iOptical power and electrical power: i-th is transmitted It is right, enable w_iIndicate Wave beam forming vector,w_i,nIndicate n-th of i-th of transmission pair The weighting coefficient of LED, n=1 ..., N,Indicate that the real number space of N-dimensional, i-th of transmitting terminal transmit information X_iIt is connect to i-th Receiving end, wherein | X_i|≤A_i,AndThe signal s that i-th of transmitting terminal is emitted_i Are as follows:

Wherein l_iFor the direct current biasing vector of i-th of user,b_iFor the direct current of i-th of user Size is biased, is necessary for non-negative due to emitting signal in visible light communication, w_iIt must satisfy:

Wherein | | it is modulus,

The resulting transmitting signal s of step 4_iOptical powerAnd electrical powerIt is respectively as follows:

Wherein i indicates the serial number of transmission pair,N indicates LED serial number in each transmitting terminal,| | | | to seek 2- norm；

Step 5, channel parameter is set: being shone model according to lambert, the channel of n-th of LED to i-th user on j-th of lamps and lanterns Gain g_i,j,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 LED, φ_1/2Indicate the half of half-power angle, η_cIndicate electro-optical efficiency, η_l Indicate photoelectric conversion efficiency, G indicates the gain of trsanscondutance amplifier, A_RIndicate receiving end physical area size,Wherein n_rIndicate receiving end collector lens refractive index, A_PDIndicate the area of photoelectric detector, sin () is SIN function, d_i,j,nIndicate n-th of LED at a distance from i-th of user, ψ_nIndicate the incidence angle of receiving end, ψ_FoVIt indicates The visual field width of user；

Step 6, according to change of direction multiplier ADMM optimization algorithm, K distributed subproblem is solved:

Wherein g_i,jFor j-th of transmitting terminal to the channel gain of i-th of user, g_i,iFor i-th of transmitting terminal to the letter of i-th of user Road gain,And

R_iIt is the targeted rate of i-th of user, e_nTo be 1 and other elements in addition to i-th of element For 0 vector, σ²For noise power, w_jFor the Wave beam forming vector of j-th of transmitting terminal, ε_jIt is inclined that direct current is not added for j-th of user The target average electrical power for the transmitting signal set；Local variable is local interference information v_i, v_i=[ν_i,1,...,ν_i,j,...ν_i,K, η_i]^T, j ≠ i, Wherein become Measure ν_i,jIndicate the interference of j-th of LED light to i-th of user；Variable η_iIndicate total interference that i-th of LED light receives, Tr () is the mark for seeking matrix；

Define global variableThe relationship of local variable and global variable are as follows:

v_i=Z_iV,

Wherein Real number space is tieed up for (K+1) × (K+1), the problem after conversion is write a Chinese character in simplified form are as follows:

Wherein subproblem f_i(v_i) is defined as:

s.t.u_iTr(W_ig_i,ig_i,i ^T)≥η_i+c_i

Simplified problem is a globally consistent problem, i.e., according to constraint condition, local variable v_iIt finally should be with global variable v Unanimously, it is solved using alternating direction multiplier ADMM algorithm, corresponding LagrangianL_ζ({v_i},τ_i, v) are as follows:

Wherein τ_iIt for the Lagrange multiplier with optimization problem constraint link, or is dual variable, ζ is penalty factor；

Step 7, the number of iterations t=0 is enabled, initializing variable v (0), τ (0) and penalty factor ζ, ξ > 0 are given precision；

Step 8, local variable { v when t+1 iteration is updated_i(t+1) } subproblem f, is solved_i(v_i) and it is following K it is distributed excellent Change problem:

WhereinExpression makes the smallest value of B, τ in A_i() is dual variable, v_i() is local variable；

Step 9, local variable { v when t+1 iteration is exchanged with other LED light_i(t+1)}；

Step 10, the global variable v (t+1) when t+1 iteration is updated, it may be assumed that

WhereinExpression makes the smallest value of B in A；

Step 11, dual variable τ when t+1 iteration is updated_i(t+1), it may be assumed that

τ_i(t+1)=τ_i(t)+ζ(v_i(t+1)-Z_iv(t+1))；

Step 12, whenWhen, terminate iteration；Otherwise, t is updated to t+1, and return step 8；

Step 13, beamformer output forms matrix { w_i}。