CN104467964B - A kind of traffic rate optimization method of indoor visible light communication - Google Patents

Abstract

The present invention discloses a kind of traffic rate optimization method of indoor visible light communication, and methods described includes：The illumination Optimization Factor of illumination channel, default lamp source central light strength and lamp source according to lamp source to user, builds user and receives illuminance model；Illuminance model is received according to user and default user receives illuminance, build user's illumination buggy model；Illuminance model and user illumination buggy model are received according to user, user's illumination is optimized, obtain the illumination Optimization Factor of lamp source；Signal and default lamp source direct current biasing after illumination Optimization Factor, ZF pre-coding matrix, default modulation according to lamp source, build the sending signal model of lamp source；Sending signal model according to lamp source, the communication channel capacity to lamp source to user is optimized, the traffic rate for being optimized.With traffic rate optimization be combined for user's illumination optimization by the method for the present invention, and lamp source is selected, and can improve indoor visible light communication performance.

Description

A kind of traffic rate optimization method of indoor visible light communication

Technical field

The present invention relates to wireless light communication field, and in particular to a kind of traffic rate optimization side of indoor visible light communication Method.

Background technology

Visible light communication is a kind of novel wireless communication technology based on light emitting diode (LED), using the bright of LED lamplight Dark change transmission information.Visible light communication has message transmission rate high, is not take up wireless frequency spectrum, without electromagnetic interference, confidentiality Good the features such as, effective supplement of existing twireless radio-frequency communication can be turned into.

Because the illumination of indoor visible light communication uses LED lamp source, in order to meet room lighting needs, can typically arrange many Individual LED lamp source, this allows for visible ray multiple-input and multiple-output (Multiple-Input Multiple-Output, MIMO) turns into It is a kind of may, and at present indoor visible light communication to there is communication distance short, it is seen that optical communication link such as easily interrupts at the defect, if filled Divide using many lamp sources of indoor deployments, i.e., by visible ray MIMO technology, it is possible to solve these problems, so as to significantly improve room Interior visible light communication system performance, promotes the development of indoor visible light technical applicationization.

At present, the international and domestic research to visible ray MIMO precoding techniques is mainly included to single user visible ray MIMO The research of the maximized optimization problem of traffic rate, the research to the pre-coding scheme under multiuser MIMO scene, to list under scape Repeated encoding (Repeat Coding) under user's MIMO scene, spatial reuse (Spatial Multiplexing), spatial modulation The Performance comparision of (Spatial Modulation), but these researchs are all the single research for communication performance.

Because indoor visible light communication system is as LED lamp source is subject to wide as the rise of novel green illumination lamp source General concern and research, so illumination is the premiere feature of LED lamp source, comparatively speaking, communication is secondary function.Simple ignores The illumination of visible light communication system needs, and the communication performance of a Study system is inadequate, but also lacks effective scheme at present, Can will be seen that optical communication system illumination needs and communication performance is effectively combined.

The content of the invention

Technical problems to be solved by the invention prior art will not only for the communication performance of visible light communication system The problem that the illumination of visible light communication system needs and system communication performance is effectively combined, and currently for communication speed The rate optimization MPAM modulation for considering, lack the precoding processing scheme suitable for various modulated signals more.

For this purpose, the present invention proposes a kind of traffic rate optimization method of indoor visible light communication, methods described includes：

The illumination Optimization Factor of illumination channel, default lamp source central light strength and lamp source according to lamp source to user, structure Build user and receive illuminance model；

Illuminance model is received according to the user and default user receives illuminance, build user's illumination deviation mould Type；

Illuminance model and user illumination buggy model are received according to the user, user's illumination is carried out excellent Change, obtain the illumination Optimization Factor of the lamp source；

Illumination Optimization Factor, ZF pre-coding matrix according to the lamp source, the signal after default modulation and default Lamp source direct current biasing, build lamp source sending signal model；

Sending signal model according to the lamp source, the communication channel capacity to lamp source to user is optimized, and obtains excellent The traffic rate of change.

Optionally, user's reception illuminance model is：

y_L=H_LΛ_LI_L；

Wherein, y_LFor user receives illuminance vector, H_LIt is the illumination channel of lamp source to user, Λ_LFor the illumination of lamp source is excellent Change factor diagonal matrix, I_LIt is default lamp source central light strength vector.

Optionally, user's illumination buggy model is：

Wherein, f_jIt is the illumination deviation of user j, y_L,jFor user j receives illuminance, y_t,jFor default user j receives light Illumination.

Optionally, it is described that illuminance model and user illumination buggy model are received according to the user, to user Illumination is optimized, and obtains the illumination Optimization Factor of the lamp source, including：

Build user and illuminate convex optimization problem：

s.t. H_LΛ_LI_L≥y_t；0≤λ_L,i≤ 1, i=1 ..., N_t；

Wherein, y_tFor default user receives illuminance vector, vector is divided by for corresponding element is divided by vector in formula, λ_L,i, i=1 ..., N_tIt is matrix Λ_LMiddle diagonal entry, N_tIt is lamp source number；

Solve the user and illuminate convex optimization problem, obtain the illumination Optimization Factor diagonal matrix Λ of lamp source_L。

Optionally, the sending signal model of the lamp source is：

X=Wd+ Λ_LP；

Wherein, d is the signal vector after default modulation, and P is default lamp source direct current biasing vector；W prelists for ZF Code matrix：

W=H^H(HH^H)^-1Λ_C；

Wherein, H is communication channel of the lamp source to user, Λ_CIt is the power allocation factor of user's independent subchannels to angular moment Battle array.

Optionally, the sending signal model according to the lamp source, the communication channel capacity to lamp source to user is carried out Optimization, the traffic rate for being optimized, including：

Build lamp source to the convex optimization problem of communication channel capacity of user：

s.t. FΛ_CI≤m₀Λ_LP；λ_C,j>=0, j=1 ..., N_r；

Wherein, λ_C,jIt is the power allocation factor of user's j independent subchannels, N_rIt is user's number；C arrives user's for lamp source Communication channel capacity, B is communication channel bandwidth of the lamp source to user, σ_jFor the noise criteria of user j is poor；

Wherein, F=abs (H^H(HH^H)^-1), I is N_rElement in × 1 vector, and I vectors is 1, m₀It is the maximum of lamp source Modulation depth；

The lamp source to the convex optimization problem of communication channel capacity of user is solved, the Λ is obtained_C, according to the Λ_C, obtain To lamp source to the communication channel capacity maximum of user.

Optionally, methods described further includes to select the following steps of lamp source：

Lamp source selective factor B α is increased to 1 since 0 according to default regulation step delta α, obtain lamp source selection because The value set { 0, Δ α, 2 Δ α ..., 1 } of sub- α；

To each the lamp source selective factor B α value in the value set, following formula is calculated：

Wherein, G=m₀Λ_LP, (G)_iIt is i-th value of element, max (G) is the element of maximum in G vector all elements； λ_A,i=1 represents selection lamp source i transmission data；λ_A,i=0 expression does not select lamp source i transmission informations, i=1 ..., N_t, N_tIt is lamp source Number；

Judge that each the lamp source selective factor B α value in the value set is correspondingWhether set up, If so, the optimization problem of lamp source selection is then solved, the corresponding communication channel capacity maximum of lamp source selective factor B α, institute is obtained State lamp source selection optimization problem be：

s.t. F_needΛ_CI≤G_need；λ_C,j>=0, j=1 ..., N_r；

Wherein,H_needRepresent that the communication of lamp source to the user of selection is believed Road matrix, G_needRepresent the vector that the element of the corresponding G vectors of lamp source of selection is constituted；

If not, then the corresponding communication channel capacity maximum of lamp source selective factor B α is set to 0；

Compare each the corresponding communication channel capacity maximum of lamp source selective factor B α values in the value set, it is determined that The corresponding lamp source selective factor B α of maximum in communication channel capacity maximum is optimal lamp source selective factor B α, the optimal lamp Selective factor B α corresponding lamp source selection schemes in source are optimal lamp source selection scheme.

Optionally, when the optimal lamp source selective factor B α is not unique, select lamp source minimum in selection lamp source selection scheme Scheme is optimal lamp source selection scheme.

Compared to prior art, a kind of traffic rate optimization method of indoor visible light communication of the invention is based on multi-user Illumination optimization is optimized to the traffic rate of visible light communication, and lamp source is selected on the basis of the traffic rate of optimization Select, further improve indoor visible light communication performance.

Brief description of the drawings

In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing The accompanying drawing to be used needed for having technology description is briefly described, it should be apparent that, drawings in the following description are this hairs Some bright embodiments, for those of ordinary skill in the art, on the premise of not paying creative work, can be with root Other accompanying drawings are obtained according to these accompanying drawings.

Fig. 1 shows the flow chart of the traffic rate optimization method of indoor visible light communication；

Fig. 2 shows MIMO signal transmission pattern；

Fig. 3 shows multi-User Indoor visible light communication schematic diagram of a scenario；

Fig. 4 (a)-(c) respectively illustrates system spectral effect comparison schematic diagram before and after optimization, and unit bandwidth Energy Efficiency Ratio is relatively illustrated Figure, general ambient light degree of deviation comparison schematic diagram.

Specific embodiment

To make the purpose, technical scheme and advantage of the embodiment of the present invention clearer, below in conjunction with the embodiment of the present invention In accompanying drawing, the technical scheme in the embodiment of the present invention is explicitly described, it is clear that described embodiment be the present invention A part of embodiment, rather than whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not having The every other embodiment obtained under the premise of creative work is made, the scope of protection of the invention is belonged to.

As shown in figure 1, the present embodiment discloses a kind of traffic rate optimization method of indoor visible light communication.In the present embodiment In, it is considered to indoor distribution has N_tIndividual lamp source, common N_rIndividual user.Illumination horizon light illumination is represented.If the illumination from lamp source to user Channel matrix is H_L, wherein the i-th column element of jth row h_L,j,iRepresent the illumination channel from lamp source i to user j：

Wherein m is lambert's factor, θ_j,iIt is the lamp source angle of departure, cos^m(θ_j,i) represent the lamp source of unit central light strength in θ_j,i Luminous intensity in angle, ψ_j,iIt is receiving terminal incidence angle, d_j,iIt is distance between lamp source and user.

All users are received using single non-imaged receiver and conciliate dim signal, and signal transmitting and receiving model is：

Y=Hx+n；

To receive electric signal vector, H is the communication channel matrix from lamp source to user to wherein y, and jth row i-th is arranged in matrix Element h_j,iRepresent and be from i-th lamp source to the communication channel of j-th user：

Wherein ρ_jIt is photoelectric conversion factors, A_jIt is receiver area, [π of (m+1)/2] cos^mθ is that the Lambertian radiation of lamp source is strong Degree, ψ_CIt is j-th angle of visual field FOV of user.N is additive noise vector, it is assumed that be real-valued Gaussian-distributed variable, average is 0.The J user's noise variance be：

Wherein q is electric charge, P_r,jIt is j-th user's average received power, B is communication channel bandwidth, χ_ambIt is ambient light Electric current, i_ampIt is amplifier noise current density.

S1, the illumination Optimization Factor for illuminating channel, default lamp source central light strength and lamp source according to lamp source to user, Build user and receive illuminance model；

User receives illuminance model：

y_L=H_LΛ_LI_L；

Wherein, y_LFor user receives illuminance vector, H_LIt is the illumination channel of lamp source to user, Λ_LFor the illumination of lamp source is excellent Change factor diagonal matrix, I_LIt is default lamp source central light strength vector, central light strength is the intrinsic parameter of lamp source, by selection Different lamp sources, obtain different central light strengths, I_LAlso the vector of the intrinsic central light strength composition of many lamp sources can be expressed as, I (0) is Lamp source central light strength, I (0) is constant, then I_L=[I (0) ..., I (0)]^T, I_LIt is N_t× 1 vector.

S2, illuminance model and default user are received according to user receive illuminance, build user's illumination deviation mould Type；

User illuminates buggy model：

Wherein, f_jIt is the illumination deviation of user j, y_L,jFor user j receives illuminance, y_t,jFor default user j receives light Illumination.

S3, according to user receive illuminance model and user illumination buggy model, to user illumination optimize, obtain The illumination Optimization Factor of lamp source；

In the present embodiment, build user and illuminate convex optimization problem：

s.t. H_LΛ_LI_L≥y_t；0≤λ_L,i≤ 1, i=1 ..., N_t；

Wherein, y_tFor default user receives illuminance vector, vector is divided by for corresponding element is divided by vector in formula, λ_L,i, i=1 ..., N_tIt is matrix Λ_LMiddle diagonal entry, N_tIt is lamp source number；

Solve the user and illuminate convex optimization problem, obtain the illumination Optimization Factor diagonal matrix Λ of lamp source_L, matrix Λ_LIn 0≤λ of diagonal entry_L,i≤ 1, i=1 ..., N_tRepresent the illumination Optimization Factor for the i-th lamp source.

S4, the illumination Optimization Factor according to the lamp source, ZF pre-coding matrix, the signal after default modulation and pre- If lamp source direct current biasing, build lamp source sending signal model；

As shown in Fig. 2 the sending signal model of lamp source is：

X=Wd+ Λ_LP；

Wherein, d is signal vector (the total N after default modulation_rIndividual element), can be OFDM, after the modulation such as MPAM Signal, P is default lamp source direct current biasing vector, and the direct current biasing of lamp source is the intrinsic parameter of lamp source, and P can also be expressed as many The vector of the intrinsic direct current biasing composition of lamp source；W is ZF pre-coding matrix：

W=H^H(HH^H)^-1Λ_C；

Wherein, H is communication channel of the lamp source to user, Λ_CIt is the power allocation factor of user's independent subchannels to angular moment Battle array, matrix diagonals line element λ_C,j, j=1 ..., N_r。

In the present embodiment, electro-optic conversion coefficient is 1, that is to say, that the sending signal model of lamp source can both represent telecommunications Number, it is also possible to optical signal is represented, wherein Wd is lamp source to the signal that the signal of the traffic channel of user is after precoding, Λ_LP is signal of the lamp source to the illumination transmission of user.

S5, the sending signal model according to the lamp source, the communication channel capacity to lamp source to user are optimized, obtained The traffic rate of optimization.

Specifically：Assuming that the sending signal Zhongj roads modulated signals d of lamp source_j∈ [- 1,1], j=1 ..., N_r, then it is pre- The scope of the signal Wd after coding is Wd ∈ [- abs (W) I, abs (W) I], wherein I=[1 ..., 1]^TIt is N_r× 1 vector.Due to The sending signal of lamp source must assure that non-negative, that is,

Wd+Λ_LP≥0；

Then there are-abs (W) I+ Λ_LP >=0, that is, abs (W) I≤Λ_LP。

If F=abs (H^H(HH^H)^-1), then above-mentioned signal nonnegativity restrictions can be expressed as：FΛ_CI≤Λ_LP.Due to being believed The influence of number Design of Amplification Circuit etc., the modulation depth of lamp source is limited, it is assumed that the modulation depth of all lamp sources is m to the maximum₀, also Have

abs(W)I≤m₀Λ_LP；

Then above-mentioned signal nonnegativity restrictions can be expressed as：

FΛ_CI≤m₀Λ_LP；

Using ZF ZF precodings, can eliminate using the multiuser interference of single antenna, it is seen that optical communication system capacity Can be expressed as：

It is high in view of each user's received signal to noise ratio, can approximately obtain

Then consider multi-user's lighting demand simultaneously, the maximized optimization problem of communication channel capacity of lamp source to user can be with It is expressed as：

s.t. FΛ_CI≤m₀Λ_LP；λ_C,j>=0, j=1 ..., N_r；

Wherein, λ_C,jIt is the power allocation factor of user's j independent subchannels, N_rIt is user's number；Lamp source illumination optimization because Sub- diagonal matrix Λ_L, 0≤λ of diagonal entry in matrix_L,i≤ 1, i=1 ..., N_tRepresent for the i-th lamp source illumination optimization because Son, C is communication channel capacity of the lamp source to user, and B is communication channel bandwidth of the lamp source to user, σ_jIt is the noise mark of user j It is accurate poor；

Wherein, F=abs (H^H(HH^H)^-1), I is N_rElement in × 1 vector, and I vectors is 1, m₀It is the maximum of lamp source Modulation depth；

The lamp source to the convex optimization problem of communication channel capacity of user is solved, the Λ is obtained_C, according to the Λ_C, obtain To lamp source to the communication channel capacity maximum of user.

Above mentioned problem is a convex optimization problem, can be solved by CVX tool boxes.

The traffic rate that above scheme is considered under the conditions of multi-user's lighting demand of indoor visible light communication system is maximum Change problem.According to illumination optimization problem, the illumination Optimization Factor for obtaining suitable each lamp source can be solved.Due to by user Number, customer location, the influence of user's illuminance changes in demand, in the case of some scenes, the direct current biasing meeting of some lamp sources Very little.And in traffic rate optimization problem, there is the constraints about direct current biasing, this causes when some lamp sources are closed, System traffic rate is greatly affected.In order to reduce this influence, it is considered in the good lamp source transmitting data of a part of condition That is Wd components, and it is 0 that data i.e. Wd components will not be transmitted in the lamp source of condition difference.

Lamp source selective factor B α is increased to 1 since 0 according to default regulation step delta α, obtain lamp source selection because The value set { 0, Δ α, 2 Δ α ..., 1 } of sub- α；

To each the lamp source selective factor B α value in value set, following formula is calculated：

Wherein, G=m₀Λ_LP, (G)_iIt is i-th value of element, max (G) is the element of maximum in G vector all elements； λ_A,i=1 represents selection lamp source i transmission data；λ_A,i=0 expression does not select lamp source i transmission informations, lamp source to be served only for illumination, i= 1,...,N_t, N_tIt is lamp source number；

Judge that each the lamp source selective factor B α value in value set is correspondingWhether set up, if into It is vertical, then the optimization problem of lamp source selection is solved, obtain the corresponding communication channel capacity maximum of lamp source selective factor B α, lamp source choosing The optimization problem selected is：

s.t. F_needΛ_CI≤G_need；λ_C,j>=0, j=1 ..., N_r；

Wherein,H_needRepresent the lamp source of selection to the communication of user Channel matrix, G_needRepresent the vector that the element of the corresponding G vectors of lamp source of selection is constituted；

If not, then the corresponding communication channel capacity maximum of lamp source selective factor B α is set to 0；

Compare each the corresponding communication channel capacity maximum of lamp source selective factor B α values in value set, it is determined that communication The corresponding lamp source selective factor B α of maximum in channel capacity maximum is optimal lamp source selective factor B α, optimal lamp source selection because The corresponding lamp source selection scheme of sub- α is optimal lamp source selection scheme.When most preferably lamp source selective factor B α is not unique, selection lamp source choosing It is optimal lamp source selection scheme to select and select in scheme the minimum scheme of lamp source.

Fig. 3 shows the multi-User Indoor visible light communication scene of the present embodiment, and room-size is 5m × 5m × 3m, smallpox 16 LED arrays are balanced distributed with plate, there are 7 × 7 LED in each LED array, belonged to every in same LED array Individual LED sends same signal.The Initial Trans of each LED are P_led=0.452W, half-power angle is 60 degree, center light It is by force I (0)=23.81cd.4 users are had, each user has 1 photelectric receiver, its photodetector area is 1cm², connect It is 0.4A/W to receive device responsiveness, and visual angle is 60 degree, and ambient noise electric current is 10.93A/m²/ Sr, preamplifier noise density is 5pA/Hz^-1/2.The coordinate position of user is respectively：[2.05 1.60 0.85], [2.05 1.40 0.85], [3.20 3.90 0.85], [3.90 3.90 0.85].Assuming that the photelectric receiver of user user is perpendicularly oriented to ceiling, the modulation depth of all LED Degree is m to the maximum₀=0.15, system bandwidth is 25MHz.Customer location and illuminance demand are as shown in table 1：

The user's indoor location of table 1 and illuminance demand

The traffic rate optimization method of the indoor visible light communication of the present embodiment is as follows：

By modes such as the position positioning to user, lamp source control computer can be estimated to obtain from 16 LED gusts respectively Each LED to 4 distance of user in row.

Assuming that being H from each lamp source (being here LED) to the illumination channel matrix of multi-user_L, the wherein column element of jth row i-th h_L,j,iRepresent the illumination channel of k-th LED to user j from lamp source i：

Wherein m is lambert's factor, θ_j,iIt is the lamp source angle of departure, cos^m(θ_j,i) represent the lamp source of unit central light strength in θ_j,i Luminous intensity in angle, ψ_j,iIt is receiving terminal incidence angle, d_j,iIt is distance between lamp source and user

Assuming that H is the communication channel matrix from lamp source to multi-user, the i-th column element of jth row h in matrix_j,iRepresent from i-th Individual lamp source is to the communication channel of j-th user：

Wherein ρ_jIt is photoelectric conversion factors, A_jIt is receiver area, [π of (m+1)/2] cos^mθ is that the Lambertian radiation of lamp source is strong Degree, ψ_CIt is j-th angle of visual field FOV of user.

All users are received using single non-imaged receiver and conciliate dim signal, and signal transmitting and receiving model is：

Y=Hx+n；

To receive electric signal vector, n is additive noise vector to wherein y, it is assumed that be real-valued Gaussian-distributed variable, average is 0. J-th user's noise variance be：

Wherein q is electric charge, P_r,jIt is j-th user's average received power, B is communication channel bandwidth, χ_ambIt is ambient light Electric current, i_ampIt is amplifier noise current density.

User receives illuminance model：

y_L=H_LΛ_LI_L；

Wherein, y_LFor user receives illuminance vector, H_LIt is the illumination channel of lamp source to user, Λ_LFor the illumination of lamp source is excellent Change factor diagonal matrix, I_LIt is default lamp source central light strength vector, I (0) is lamp source central light strength, and I (0) is constant, then I_L= [I(0),...,I(0)]^T, I_LIt is N_t× 1 vector.

User illuminates buggy model：

Wherein, f_jIt is the illumination deviation of user j, y_L,jFor user j receives illuminance, y_t,jFor default user j receives light Illumination.

Build user and illuminate convex optimization problem：

s.t. H_LΛ_LI_L≥y_t；0≤λ_L,i≤ 1, i=1 ..., N_t；

Wherein, y_tFor default user receives illuminance vector, λ_L,i, i=1 ..., N_tIt is matrix Λ_LIn diagonal line element Element, N_tIt is lamp source number；The real-time illumination light illumination requirement of oneself can be fed back to lamp source control and calculated by user in the present embodiment Machine, or lamp source control computer, according to the time at that time, the predefined setting of user determines the illumination illuminance of each user, So that it is determined that y_t, vector is divided by for corresponding element is divided by vector in formula；

Solve the user and illuminate convex optimization problem, obtain the illumination Optimization Factor diagonal matrix Λ of lamp source_L, it is right in matrix 0≤λ of diagonal element_L,i≤ 1, i=1 ..., N_tRepresent the illumination Optimization Factor for the i-th lamp source.

Support that multi-user's illuminance is adjusted and the visible light signal transmission pattern of MIMO precodings is：

X=Wd+ Λ_LP；

Wherein, d is signal vector (the total N after default modulation_rIndividual element), P be default lamp source direct current biasing to Amount, it is assumed here that LED current is linear with transmit power, each element is all 0.452 in P；W is ZF pre-coding matrix：

W=H^H(HH^H)^-1Λ_C；

Wherein, H is communication channel of the lamp source to user, Λ_CIt is the power allocation factor of user's independent subchannels to angular moment Battle array, matrix diagonals line element λ_C,j, j=1 ..., N_r。

In the present embodiment, electro-optic conversion coefficient is 1, that is to say, that the sending signal model of lamp source can both represent telecommunications Number, it is also possible to optical signal is represented, wherein Wd is lamp source to the signal that the signal of the traffic channel of user is after precoding, Λ_LP is signal of the lamp source to the illumination transmission of user.

Assuming that the sending signal Zhongj roads modulated signals d of lamp source_j∈ [- 1,1], j=1 ..., N_r, then after precoding The scope of signal Wd is Wd ∈ [- abs (W) I, abs (W) I], wherein I=[1 ..., 1]^TIt is N_r× 1 vector.Due to lamp source array Sending signal must assure that non-negative, that is,

Wd+Λ_LP≥0；

Then there are-abs (W) I+ Λ_LP >=0, that is, abs (W) I≤Λ_LP。

If F=abs (H^H(HH^H)^-1), then above-mentioned signal nonnegativity restrictions can be expressed as：FΛ_CI≤Λ_LP.Due to being believed The influence of number Design of Amplification Circuit etc., the modulation depth of lamp source is limited, it is assumed that the modulation depth of all lamp sources is m to the maximum₀, also Have

abs(W)I≤m₀Λ_LP；

Then above-mentioned signal nonnegativity restrictions can be expressed as：

FΛ_CI≤m₀Λ_LP；

Using ZF ZF precodings, can eliminate using the multiuser interference of single antenna, it is seen that optical communication system capacity Can be expressed as：

It is high in view of each user's received signal to noise ratio, can approximately obtain

Then consider multi-user's lighting demand simultaneously, the maximized optimization problem of communication channel capacity of lamp source to user can be with It is expressed as：

s.t. FΛ_CI≤m₀Λ_LP；λ_C,j>=0, j=1 ..., N_r；

Wherein, λ_C,jIt is the power allocation factor of user's j independent subchannels, N_rIt is user's number；Lamp source illumination optimization because Sub- diagonal matrix Λ_L, 0≤λ of diagonal entry in matrix_L,i≤ 1, i=1 ..., N_tRepresent for the i-th lamp source illumination optimization because Son, C is communication channel capacity of the lamp source to user, and B is communication channel bandwidth of the lamp source to user, σ_jIt is the noise mark of user j It is accurate poor；

Wherein, F=abs (H^H(HH^H)^-1), I is N_rElement in × 1 vector, and I vectors is 1, m₀It is the maximum of lamp source Modulation depth；

The lamp source to the convex optimization problem of communication channel capacity of user is solved, the Λ is obtained_C, according to the Λ_C, obtain To lamp source to the communication channel capacity maximum of user.

Lamp source array selective factor B α is increased to 1 since 0 according to default regulation step delta α, the lamp source battle array is obtained The value set { 0, Δ α, 2 Δ α ..., 1 } of column selection factor-alpha；

To each the lamp source array selective factor B α value in value set, following formula is calculated：

Wherein, G=m₀Λ_LP, (G)_iIt is i-th value of element, max (G) is the element of maximum in G vector all elements； λ_A,i=1 represents selection lamp source i transmission data；λ_A,i=0 expression does not select lamp source i transmission informations, lamp source to be served only for illumination, i= 1,...,N_t, N_tIt is lamp source number；

Judge that each the lamp source array selective factor B α value in value set is correspondingWhether set up, If so, the optimization problem of lamp source selection is then solved, the corresponding communication channel capacities of lamp source array selective factor B α is obtained very big It is worth, the optimization problem of lamp source selection is：

s.t. F_needΛ_CI≤G_need；λ_C,j>=0, j=1 ..., N_r；

Wherein,H_needRepresent the lamp source of selection to the communication of user Channel matrix, G_needRepresent the vector that the element of the corresponding G vectors of lamp source of selection is constituted；

If not, then the corresponding communication channel capacity maximum of lamp source array selective factor B α is set to 0；

Compare each the corresponding communication channel capacity maximum of lamp source array selective factor B α values in value set, it is determined that The corresponding lamp source array selective factor B α of maximum in communication channel capacity maximum is optimal lamp source array selective factor B α, most The corresponding lamp source selection scheme of good lamp source array selective factor B α is optimal lamp source selection scheme.Optimal lamp source array selective factor B α When not unique, it is optimal lamp source selection scheme that the minimum scheme of lamp source is selected in selection lamp source selection scheme.

Table 2 is the Performance comparision that each scheme in the case of 400lx illuminance is required for each user.Individually for communication Prioritization scheme, sets Λ_LIntermediate value all 1, i.e., only carry out traffic rate optimization, and the illuminating effect of user is not considered, its user Illuminance cannot change with user's request.Comparatively speaking, declined using illumination communication combined optimization scheme spectrum efficiency, But system unit efficiency gets a promotion, the illumination degree of deviation is 0, and each user can obtain the illuminance for complying fully with oneself requirement. Illumination communication combined optimization scheme based on lamp source selection, under the conditions of illuminating effect is ensured, the illumination communication joint that compares is excellent Change scheme, improves spectrum efficiency and unit bandwidth efficiency.

Each prioritization scheme Performance comparision under the conditions of the user's same light illumination requirement of table 2

Table 3 is to be followed successively by 400lx, 400lx, 700lx for each user's illuminance demand, the performance of each scheme during 700lx Compare.Herein for the lighting demand for reaching user, there is lamp source transmission power very little or non-transmission power, cause communicativeness Can degradation；Selected by lamp source, wherein regulation step delta α=0.1, selects suitable lamp source to be communicated, it is ensured that to be The spectrum efficiency and efficiency of system.

Each prioritization scheme Performance comparision under the user of table 3 difference illuminance demand condition

When considering that all user's illuminance demands are identical, with the increase of user's request illuminance, the change of systematic function. With the change of illuminance, for communication performance, Fig. 4 (a) compares the change of spectrum efficiency before and after optimization, and Fig. 4 (b) compares The change of system energy efficiency before and after optimization, the scheme of proposition improves system energy efficiency with certain spectrum efficiency as cost.The opposing party Face, for illumination performance, such as shown in Fig. 4 (c), because the system after optimization can realize illumination adjustments, user's illumination deviation Degree is small, and user can obtain the illuminance for more meeting oneself needs, comparatively speaking, the system illumination degree of deviation of optimization not used Greatly, it is all that there is greater advantage compared to less optimization system using the prioritization scheme for proposing.

Although being described in conjunction with the accompanying embodiments of the present invention, those skilled in the art can not depart from this hair Various modifications and variations are made in the case of bright spirit and scope, such modification and modification are each fallen within by appended claims Within limited range.

Claims (4)

1. the traffic rate optimization method of a kind of indoor visible light communication, it is characterised in that methods described includes：

The illumination Optimization Factor of illumination channel, default lamp source central light strength and lamp source according to lamp source to user, builds and uses Family receives illuminance model；

Illuminance model is received according to the user and default user receives illuminance, build user's illumination buggy model；

Illuminance model and user illumination buggy model are received according to the user, user's illumination is optimized, obtained To the illumination Optimization Factor of the lamp source；

Signal and default lamp after illumination Optimization Factor, ZF pre-coding matrix, default modulation according to the lamp source Source direct current biasing, builds the sending signal model of lamp source；

Sending signal model according to the lamp source, the communication channel capacity to lamp source to user is optimized, optimized Traffic rate；

It is described that illuminance model and user illumination buggy model are received according to the user, user's illumination is carried out excellent Change, obtain the illumination Optimization Factor of the lamp source, including：

Build user and illuminate convex optimization problem：

$\underset{{\mathrm{\Λ}}_L}{min}\left|\right|(H_L{\mathrm{\Λ}}_L{I}_L-y_t)/y_t|{|}_1;$

s.t.H_LΛ_LI_L≥y_t；Λ_LMiddle diagonal entry is λ_L,i, i=1 ..., N_t；

Wherein, y_tFor default user receives illuminance vector, vector is divided by for corresponding element is divided by vector in formula, λ_L,iRepresent For the illumination Optimization Factor of the i-th lamp source, 0≤λ_L,i≤ 1, N_tIt is lamp source number；

Solve the user and illuminate convex optimization problem, obtain the illumination Optimization Factor diagonal matrix Λ of lamp source_L；

The sending signal model of the lamp source is：

X=Wd+ Λ_LP；

Wherein, d is the signal vector after default modulation, and P is default lamp source direct current biasing vector；W is ZF precoding square Battle array：

W=H^H(HH^H)^-1Λ_C；

Wherein, H is communication channel of the lamp source to user, Λ_CIt is the power allocation factor diagonal matrix of user's independent subchannels；

The sending signal model according to the lamp source, the communication channel capacity to lamp source to user is optimized, and obtains excellent The traffic rate of change, including：

Build lamp source to the convex optimization problem of communication channel capacity of user：

$\begin{array}{cc}\underset{{\mathrm{\Λ}}_C}{max}& C=2B\underset{j=1}{\overset{N_r}{\mathrm{\Σ}}}{\log }_2\left(\frac{{\mathrm{\λ}}_{C,j}}{{\mathrm{\σ}}_j}\right)\end{array};$

s.t.FΛ_CI≤m₀Λ_LP；λ_C,j>=0, j=1 ..., N_r；

Wherein, λ_C,jIt is the power allocation factor of user's j independent subchannels, N_rIt is user's number；C is that the communication of lamp source to user is believed Road capacity, B is communication channel bandwidth of the lamp source to user, σ_jFor the noise criteria of user j is poor；

Wherein, F=abs (H^H(HH^H)^-1), I is N_rElement in × 1 vector, and I vectors is 1, m₀It is the maximum modulation of lamp source Depth；

The lamp source to the convex optimization problem of communication channel capacity of user is solved, the Λ is obtained_C, according to the Λ_C, obtain lamp Communication channel capacity maximum of the source to user；

Methods described further includes to select the following steps of lamp source：

Lamp source selective factor B α is increased to 1 since 0 according to default regulation step delta α, the lamp source selective factor B α is obtained Value set { 0, Δ α, 2 Δ α ..., 1 }；

To each the lamp source selective factor B α value in the value set, following formula is calculated：

${\mathrm{\&lambda;}}_{A,i}=\left\{\begin{array}{cc}1,& {\left(G\right)}_i>=\mathrm{\&alpha;}max\left(G\right)\\ 0,& {\left(G\right)}_i<\mathrm{\&alpha;}max\left(G\right)\end{array}\right.;$

Wherein, G=m₀Λ_LP, (G)_iIt is i-th value of element, max (G) is the element of maximum in G vector all elements；λ_A,i= 1 represents selection lamp source i transmission data；λ_A,i=0 expression does not select lamp source i transmission informations, i=1 ..., N_t, N_tIt is lamp source number；

Judge that each the lamp source selective factor B α value in the value set is correspondingWhether set up, if into It is vertical, then the optimization problem of lamp source selection is solved, obtain the corresponding communication channel capacity maximum of lamp source selective factor B α, the lamp Source selection optimization problem be：

$\begin{array}{cc}\underset{{\mathrm{\&Lambda;}}_C}{max}& C=2B\underset{j=1}{\overset{N_r}{\mathrm{\&Sigma;}}}{\log }_2\left(\frac{{\mathrm{\&lambda;}}_{C,j}}{{\mathrm{\&sigma;}}_j}\right)\end{array};$

s.t.F_needΛ_CI≤G_need；λ_C,j>=0, j=1 ..., N_r；

Wherein,H_needRepresent the lamp source of selection to the communication channel square of user Battle array, G_needRepresent the vector that the element of the corresponding G vectors of lamp source of selection is constituted；

If not, then the corresponding communication channel capacity maximum of lamp source selective factor B α is set to 0；

Compare each the corresponding communication channel capacity maximum of lamp source selective factor B α values in the value set, it is determined that communication The corresponding lamp source selective factor B α of maximum in channel capacity maximum is optimal lamp source selective factor B α, the optimal lamp source choosing The corresponding lamp source selection scheme of factor-alpha is selected for optimal lamp source selection scheme.

2. method according to claim 1, it is characterised in that the user receives illuminance model and is：

y_L=H_LΛ_LI_L；

Wherein, y_LFor user receives illuminance vector, H_LIt is the illumination channel of lamp source to user, Λ_LFor lamp source illumination optimization because Sub- diagonal matrix, I_LIt is default lamp source central light strength vector.

3. method according to claim 2, it is characterised in that user's illumination buggy model is：

$f_j=\left|\frac{y_{L,j}-y_{t,j}}{y_{t,j}}\right|;$

Wherein, f_jIt is the illumination deviation of user j, y_L,jFor user j receives illuminance, y_t,jFor default user j receives illuminance.

4. method according to claim 1, it is characterised in that when the optimal lamp source selective factor B α is not unique, select lamp It is optimal lamp source selection scheme that the minimum scheme of lamp source is selected in the selection scheme of source.