CN103401611B - Coal mine work area visible light communication distributed light source method for arranging - Google Patents

Abstract

A kind of coal mine work area visible light communication distributed light source method for arranging, belongs to coal mine work area light source arrangement method.The present invention is on the basis of the LED light source illumination patterns and optical signal power distributed model that provide visible ray in underground coal mine working face, top is divided into by mine working face cuboid communication space to be square some little communication space, little communication space is uniformly distributed high-power essential safe type white LED light source in the mode that each LED light source is equal to adjacent light source or border standoff distance on hydraulic support, and by making receiving plane light signal intensity reach optimum based on the scheme revising edge light power.Underground coal mine working face constant power is uniformly distributed the model of LED light source, ensure that receiving plane wireless optical signal uniform fold, can reach the double requirements of LED light source in mine working face communication and illumination; By revising edge or four position, limit light source powers further, ensureing receptivity, enabling receiving plane light signal standard deviation be reduced to original about 50%.

Description

Coal mine work area visible light communication distributed light source method for arranging

Technical field

The present invention relates to a kind of coal mine work area light source arrangement method, particularly a kind of coal mine work area visible light communication distributed light source method for arranging.

Background technology

At present, colliery audio frequency, video, data information transfer mainly realize the aboveground real time communication in down-hole by means of the wired and wireless communication mode combined, along with the driving face communication space of coal-winning machine constantly changes, it is wired very inconvenient to lay, and radio communication is optimal communication mode.Traditional radio leakage, Personal Handyphone System, CDMA, WiFi communication technology all have some limitations in down-hole application.Radio leakage communication technology cost is high, energy consumption is large, Personal Handyphone System is also withdrawn from the market gradually, WiFi is wireless communication technology up-to-date at present, this several wireless communication technology is all by airwave communication, Mine Communication space is the confined space, during radio wave transmissions, multipath phenomenon is serious, data accuracy is ensured in order to overcome multipath phenomenon, the complexities such as signal madulation mode, communication equipment increase greatly, meanwhile, data rate limit, within 100Mbps, cannot reach high data rate.

Visible light communication is simple by light-emitting diode transceiver, transmission speed is fast, the error rate is low, multipath phenomenon is weak, illumination is provided while communication, simultaneously, the visible light communication space of underground coal mine working face does not have the strong background noises such as sunlight to disturb compared with ground communication space, light source background noise is little, light source is exactly signal source, the albedo of rib to visible ray of black is weak simultaneously, energy of reflection light is about about 5% of incident light illumination, the light signal arriving optical receiver after the decay of air medium certain transmission range is almost negligible, visible light communication system solves a kind of efficient communication technology of Underground Wireless Communication in Coal Mine.

Adopting intensity modulated in visible light communication system more---the mode of direct-detection realizes data communication, the lightwave signal that direct-detection is sent by photodetector direct detection LED, thus communication efficiency will be made to reach optimum, the luminance signal that same level distributes must be made to change less, namely more evenly communication even results is better for the distribution of same level light signal, thus reduce the requirement of communications receiving equipment, communications receiving equipment is simplified.How to improve the covering uniformity of receiving plane light signal, distribute closely related with LED light source, the even square formation LED distribution light source layout having OMEGA engineering research team to propose, the Nakagawa research team of keio university of Japan is in order to the convenience of Project Realization, propose grouping LED array light source layout, the people such as the Wang Zixiong of Nanyang Technological University in 2012 propose the distribution pattern of 12+4, 12 LED light sources be uniformly distributed in r be radius circumferentially, 4 LED light sources are distributed in square communication space 4 corners, thus reduce the fluctuation of light-receiving plane signal to noise ratio.

The receiving equipment of Sony Co., Ltd. application, transmitting apparatus and communication system patent, patent No. CN 1316835A, give a kind of receiving equipment and the transmitting apparatus of energy reliable diffusion and reception high-speed optical signal, and adopt the communication system of this equipment, wherein transmitting apparatus uses white light LED array, as 4 row 4 row LED array, all LED powers are identical, for the illumination in office or family with communicate.Nanjing Univ. of Posts and Telecommunications 2012 application based on the precoding MU-MIMO indoor visible light communication system of white light LEDs through signal precoding, LED array is adopted to send light signal again, receiving circuit exports through signal output processing unit, multi-user interference is eliminated with this, the complexity of effective reduction receiving terminal, does not mention the concrete form of LED array.

In more design method, Problems existing is: one is the research that the research distributed for LED light source in visible light communication both at home and abroad is all limited to square bodily form communication space, its distribution of light sources method can not be directly applied for the communication space of mine working face cuboid, and layout method is comparatively numerous and diverse, not easily realize in the hydraulic support top board layout in narrow and small working face space.Two is that LED light source used is constant power light source, the uniformity effects improving light receiving surface signal is reached by changing LED layout, this method not only limited efficiency, and can not for difform communication space, tool is not general and complicated in the enforcement of coal mine work area change source layout.

Summary of the invention

Object of the present invention provides a kind of visible light communication distributed light source method for arranging for coal mine work area, and the method is simpler than existing method, easily implements, and effectively can be applicable to the hydraulic support top board layout in narrow and small working face space.The research method complexity solving LED light source distribution in current visible light communication is not easily implemented, and is not suitable for the problem of mine working face layout.

For achieving the above object, technical scheme of the present invention is: be divided into top to be square some little communication space underground coal mine working face cuboid communication space, the mode that little communication space adopts each LED light source to be adjacent light source or border standoff distance equivalent is uniformly distributed high-power essential safe type white LED light source on hydraulic support, is namely uniformly distributed formula LED light source layout method at coal mine work area cuboid communication space constant power; On this basis, further correction edge light power, being spatially located at edge or four position, limit LED light source power so that photo-detector receiving plane signal to noise ratio deviation average mean square error is minimum for criterion adjusts visible light communication, is the formula that the is uniformly distributed LED light source layout method based on edge power revised law; Two kinds of modes are all to set up the Received signal strength model of structure coal mine work area light receiving surface for analysis foundation.

Described coal mine work area cuboid communication space constant power is uniformly distributed formula LED light source layout method:

Adopt homogeneous space segmentation mode be with coal mine work area hydraulic support top board composition plane be upper plane, with the length of hydraulic support top board for the length of side, become by coal mine work area visible light communication compartition top to be square some communication spaces, each communication space adopts non-uniform manner to distribute high-power essential safe type white LED light source;

Communication space illuminance after division is under the condition of 300 ~ 1500lx lighting criteria of meeting international standards organization establishment, in communication process, transmitting terminal blocks to receiving terminal clear, and LED light source power is enough large can receive LED light source information to meet receiving terminal receiving equipment photodetector, each LED light source is adjacent light source or border is uniformly distributed high-power essential safe type white LED light source in the mode that standoff distance is equivalent on hydraulic support.

The described formula that the is uniformly distributed LED light source layout method based on edge power revised law:

The standard deviation proposed in the present invention based on edge power revised law minimizes method of adjustment, and the LED light source enclosed at edge one has identical transmitting power, and other LED light source still adopts identical high-power LED light source.

Pointolite array is the capable N row of L, and acceptance point r (x, y, z) received signal power Ps is:

$P_s(x,y,z)=R^2{H}^2\left(0\right)M^2\stackrel{\‾}{f^2\left(t\right)}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{P}_t(i,j)$

In formula: x, y, z are three-dimensional space position coordinate, mean receiving power is P _r=P _th (0), wherein P _tfor the average transmit power of LED, suppose that LED transmits as p _t=P _t(1+M*f (t)), M is the index of modulation, and f (t) is OOK modulation bipolar signal, Received signal strength s _t=R*H (0) P _t* M*f (t), R are the response gain constant of photodetector;

H (0) is channel DC current gain m=ln (1/2)/ln (cos φ _1/2), φ _1/2for the half-power angle of LED, can check in the LED property parameters that dispatches from the factory, LED type number is determined, parameter m just determines, and φ is the light angle of departure, and A is the light receiving area of photodetector;

P _t(i, j) is the average transmit power of the i-th row j row point-source of light in array of source;

The degree that signal to noise ratio departs from its mean value represents with standard deviation D,

Wherein, s is overall light-receiving area of plane s=max (x) * max (y), the length that max (x), max (y) are communication space and wide;

time, try to achieve P _tvalue be the performance number of edge light.

Four limits or marginal position LED light source power is spatially located at for criterion adjusts visible light communication so that photo-detector receiving plane signal to noise ratio deviation average mean square error is minimum, make the optical signal receive power uniformity of receiving plane best, edge LED light source transmitting power is same adjustable value, and all the other LED light source power remain unchanged:

Step 1, add up the average signal-to-noise ratio of whole communication space at a certain receiving plane photodetector;

Step 2, photodetector to be placed in below edge, communication space limit LED light source and to draw signal to noise ratio size, adjustment edge LED light source power, utilize the minimum power of PC judgement when signal to noise ratio departs from average signal-to-noise ratio error at tolerance interval, this power is set to this edge LED light source transmitting power;

Step 3, in due order rule adjust edge, four limits LED light source power respectively, and four drift angle LED light source power are by the adjustment of one of them edge power value;

The minimum power when signal to noise ratio departs from average signal-to-noise ratio error at tolerance interval comprises following steps to utilize PC to judge:

Step 1, edge LED light source initial gain value is arranged identical with non-edge LED light source;

Step 2, edge calculation LED light source underlying photoelectric detector receiving plane signal to noise ratio and with whole communication space average signal-to-noise ratio standard deviation;

Step 3, increase fixed value, namely increasing fixed value is that 0.3W adjusts edge LED light source performance number, until calculate standard deviation to be less than acceptable error scope, namely error range is 0.01, then this value is set to edge LED light source performance number at every turn;

If step 4 standard deviation is greater than acceptable error scope all the time, will show that standard deviation is minimum, power when namely standard deviation no longer reduces is as edge LED light source power.

In order to improve the uniformity of receiving plane light signal, simplifying the complexity of optical communication receiving equipment, have studied underground coal mine working face LED light source illumination patterns and optical signal power distributed model.The Received signal strength model of described structure coal mine work area light receiving surface, is generalized to the snr computation model of the signal strength signal intensity of multiple spot LED light source receiving optical signals, light signal from the snr computation model of the signal strength signal intensity of single-point LED light source receiving optical signals, light signal;

The signal strength signal intensity of receiving optical signals, the snr computation model of light signal have single-point LED light source and multiple spot LED light source:

(1) single-point LED light source

When LED light source is a single point light source, light source space coordinate position and launch point three dimensional space coordinate are (xs, ys, zs), optical receiver point central three-dimensional spatial coordinate location is (xr, yr, zr), Ф represents that LED sends the luminous flux of visible ray, and the luminous intensity of point-source of light is in formula, Ir represents luminous flux d Φ and the ratio of light source in assigned direction dw angle.

The distance d of light receiving area dA, the angle dw of optical receiver, light source and acceptance point and angle of light θ, between geometrical relationship be:

d ²*dw＝dA*cosθ (2)

Illuminance E in receiving plane, is defined as the luminous flux in unit are, namely

Formula (1), (2) substitute into formula (3) and obtain $E=\frac{I_r}{d^2}*\cos \mathrm{\θ}---\left(4\right)$

The luminous intensity I of LED _rto specific LED production technology and encapsulate relevant, assuming that white light LEDs meets lambert's irradiation, LED luminous intensity $I_r=\frac{(m+1)}{2\mathrm{\π}}*{\cos }^m\mathrm{\φ},---\left(5\right)$

In formula: m=ln (1/2)/ln (cos φ _1/2), φ _1/2for the half-power angle of LED, can check in the LED property parameters that dispatches from the factory, LED type number is determined, parameter m just determines, and φ is the light angle of departure.

Formula (5) is substituted into formula (4), then illuminance

Underground coal mine working face LED light source is installed on hydraulic support, and adopt the mounting means in vertical and horizontal face, receiving plane is parallel to horizontal plane, and namely the top plane of LED light source is parallel with receiving plane, and now angle of light is equal with the light angle of departure, i.e. θ=φ;

Now, $\cos \mathrm{\θ}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}}---\left(7\right)$

Then illuminance E is $E=\frac{m+1}{2\mathrm{\π}{d}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}}\right)}^{m+1}---\left(8\right)$

In visible light communication system, the light that receiving plane receives derives from two parts, and a part receives (line ofsight) for straight line, derives from the direct irradiation of light source; A part receives (not line of sight) for non-rectilinear, is mainly derived from illumination that light source sends and is mapped to the light that ground, wall, bar etc. be reflected back and is received detector reception.For LOS straight length, luminous power is:

H(w)＝H(0)e ^-jwτ，

H (0) is channel DC current gain $H\left(0\right)=\frac{(m+1)A}{2\mathrm{\π}{d}^2}\cos \mathrm{\θ}*{\cos }^m\mathrm{\φ},---\left(9\right)$

In formula: A is the light receiving area of photodetector, τ is time delay;

Mean receiving power is P _r=P _th (0), wherein P _tfor the average transmit power of LED, suppose that LED transmits as P _t=P _t(1+M*f (t)), M is the index of modulation, and f (t) is OOK modulation bipolar signal, Received signal strength s _t=R*H (0) P _t* M*f (t), R are the response gain constant of photodetector;

System noise than SNR is $\mathrm{SNR}=\frac{P_S}{P_{\mathrm{noise}}}=\frac{R^{2}H{\left(0\right)}^2{P}_t^2{M}^2\stackrel{\‾}{f{\left(t\right)}^2}}{P_{\mathrm{noise}}}---\left(10\right)$

When signal transmitting power, the index of modulation and modulation bipolar signal average power are stablized, received signal power P _sdirect ratio and H ², thus relevant to the distance of acceptance point, the light angle of departure, angle of light size to light source (0).

(2) multiple spot LED light source

When light source is multiple distribution type LED light source, receiving plane acceptance point (xr, yr, zr) place illumination is be the illumination sum of the i-th row jth row top light source acceptance point for this reason, pointolite array is the capable N row of L;

Acceptance point r (x, y, z) received signal power Ps is

$P_s(x,y,z)=R^2{H}^2\left(0\right)M^2\stackrel{\‾}{f^2\left(t\right)}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{P}_t(i,j)---\left(11\right)$

The signal to noise ratio snr of acceptance point r (x, y, z) is:

Receiving plane signal to noise ratio snr average is: wherein s is light-receiving area of plane s=max (x) * max (y), the length that max (x), max (y) are communication space and wide;

The degree of signal to noise ratio deviation average represents with standard deviation D:

$D=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\∫}}\underset{0}{\overset{\max \left(x\right)}{\∫}}(\frac{P_s(x,y)}{P_{\mathrm{noise}}}-\stackrel{\‾}{\mathrm{SNR}})\mathrm{dxdy}---\left(13\right)$

Standard deviation D is less, then light signal distributing homogeneity is better.

Beneficial effect and the advantage of employing such scheme are as follows:

(1) constant power is uniformly distributed formula LED light source, use the even square formation distributed layout visible light communication light sources such as LED light source, ensure that receiving plane wireless optical signal intensity covers uniformity, communication and illumination double duty can be realized, be easy to simpler than current layout method realizes, and is applicable to underground coal mine working face very formalism optical communication space.

(2) based on the formula that the is uniformly distributed LED light source design optimization method of edge power revised law, adopt the transmitting power of receiving plane signal to noise ratio deviation average minimum mean-squared error criterion adjustment edge LED light source, make the optical signal receive power uniformity of the receiving plane when not needing to change source layout best, there is more excellent light signal and be uniformly distributed performance, better communication efficiency and illuminating effect, receiving plane light signal standard deviation can be reduced to original about 50%.Being easy to realize than the method reaching the uniformity improving light receiving surface signal at present by changing LED layout, there is generality, be applicable to the communication space of difformity or layout, and implement simple.

Accompanying drawing explanation

Fig. 1 is that single led point-source of light of the present invention irradiates schematic diagram.

Fig. 2 is that multiple LED point light source of the present invention irradiates schematic diagram.

Fig. 3 is visible light communication mining face under mine scene of the present invention.

Fig. 4 is 4m*20m working face LED light source of the present invention distribution.

Fig. 5 is the even LED distribution receiving plane illuminance of constant power of the present invention and contour distribution.

Fig. 6 is edge of the present invention LED power and receiving plane lighting standard difference relation.

Fig. 7 is edge of the present invention LED power 10w receiving plane illuminance and contour distribution.

In figure, 1, launch point; 2, acceptance point; 3, LED light source; 4, hydraulic support; 5, the communication space divided; 6, coal-winning machine; 7, receiving equipment photodetector.

Embodiment

For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with drawings and Examples 1,2, the present invention is described in further detail.

Build the Received signal strength model of coal mine work area light receiving surface, the Received signal strength model of light receiving surface comprises the signal strength signal intensity of single-point LED light source and multiple spot LED light source receiving optical signals, the snr computation model of light signal; Be divided into top to be square some little communication space underground coal mine working face cuboid communication space, the mode that little communication space adopts each LED light source to be adjacent light source or border standoff distance equivalent is uniformly distributed high-power essential safe type white LED light source on hydraulic support; And revise edge light power, be namely spatially located at edge or four position, limit LED light source power so that photo-detector receiving plane signal to noise ratio deviation average mean square error is minimum for criterion adjusts visible light communication.Make the optical signal receive power uniformity of receiving plane best, obtain optimum communication efficiency and lighting effect.

Coal mine work area visible light communication space is microscler communication space, work face length is tens meters and arrives hundreds of rice, wide and high is several meters to tens meters, substantial communication space is that hydraulic support top beam is to ground, hydraulic support column is between coal-winning machine or coal seam, in communication process, transmitting terminal blocks to receiving terminal clear, and LED light source power is enough large can receive LED light source information to meet receiving terminal receiving equipment photodetector, and concrete length is not limit.

Embodiment 1: first the method builds LED light source illumination patterns and the optical signal power distributed model of visible ray in underground coal mine working face, is uniformly distributed formula LED light source to underground coal mine working face cuboid communication space constant power and carries out layout.

Described coal mine work area cuboid communication space constant power is uniformly distributed formula LED light source layout method:

The mode of described employing homogeneous space segmentation is upper plane with the plane of coal mine work area hydraulic support top board composition, with the length of hydraulic support top board for the length of side, top is become by coal mine work area visible light communication compartition to be square some communication spaces, each communication space adopts non-uniform manner distribution high-power, adopts 5W essential safe type white LED light source;

Communication space illuminance after division is under the condition of 300 ~ 1500lx lighting criteria of meeting international standards organization establishment, and each LED light source is adjacent light source or border is uniformly distributed high-power essential safe type white LED light source in the mode that standoff distance is equivalent on hydraulic support.

Devise coal mine work area constant power and be uniformly distributed formula LED light source layout.At wide 4m, the even square formation layout of the top design LED light source of the communication space hydraulic support of long 20m as shown in Figure 3, first space uniform split plot design is at equal intervals adopted to be divided into 5 small size square spaces, according to square array design light source point position, the spacing d=1m of adjacent two light source points, communication space height is 3m, and the height of light-receiving plane is 0.85m, and LED light source power is the great power LED intrinsic safety type light source of 5w.

The Received signal strength model of described structure coal mine work area light receiving surface, is generalized to the snr computation model of the signal strength signal intensity of multiple spot LED light source receiving optical signals, light signal from the snr computation model of the signal strength signal intensity of single-point LED light source receiving optical signals, light signal;

The signal strength signal intensity of receiving optical signals, the snr computation model of light signal have single-point LED light source and multiple spot LED light source:

(1) single-point LED light source

In FIG, when LED light source is a single point light source, light source space coordinate position and launch point three dimensional space coordinate are (xs, ys, zs), optical receiver point central three-dimensional spatial coordinate location is (xr, yr, zr), Ф represents that LED sends the luminous flux of visible ray, and the luminous intensity of point-source of light is in formula, Ir represents luminous flux d Φ and the ratio of light source in assigned direction dw angle.

The distance d of light receiving area dA, the angle dw of optical receiver, light source and acceptance point and angle of light θ, between geometrical relationship be

d ²*dw＝dA*cosθ (2)

Illuminance E in receiving plane, is defined as the luminous flux in unit are, namely

Formula (1), (2) substitute into formula (3) and obtain $E=\frac{I_r}{d^2}*\cos \mathrm{\θ}.---\left(4\right)$

The luminous intensity I of LED _rto specific LED production technology and encapsulate relevant, assuming that white light LEDs meets lambert's irradiation, LED luminous intensity $I_r=\frac{(m+1)}{2\mathrm{\π}}*{\cos }^m\mathrm{\φ},---\left(5\right)$

In formula: m=ln (1/2)/ln (cos φ _1/2), φ _1/2for the half-power angle of LED, can check in the LED property parameters that dispatches from the factory, LED type number is determined, parameter m just determines, and φ is the light angle of departure.

Formula (5) is substituted into formula (4), then illuminance

Underground coal mine working face LED light source is installed on hydraulic support, and adopt the mounting means in vertical and horizontal face, receiving plane is parallel to horizontal plane, and namely the top plane of LED light source is parallel with receiving plane, and now angle of light is equal with the light angle of departure, i.e. θ=φ;

Now, $\cos \mathrm{\θ}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}}---\left(7\right)$

Then illuminance E is $E=\frac{m+1}{2\mathrm{\π}{d}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}}\right)}^{m+1}---\left(8\right)$

In visible light communication system, the light that receiving plane receives derives from two parts, and a part receives (line ofsight) for straight line, derives from the direct irradiation of light source; A part receives (not line of sight) for non-rectilinear, is mainly derived from illumination that light source sends and is mapped to the light that ground, wall, bar etc. be reflected back and is received detector reception.For LOS straight length, luminous power is:

H(w)＝H(0)e ^-jwτ，

H (0) is channel DC current gain $H\left(0\right)=\frac{(m+1)A}{2\mathrm{\π}{d}^2}\cos \mathrm{\θ}*{\cos }^m\mathrm{\φ},---\left(9\right)$

In formula: A is the light receiving area of photodetector, τ is time delay;

Mean receiving power is P _r=P _th (0), wherein P _tfor the average transmit power of LED, suppose that LED transmits as p _t=P _t(1+M*f (t)), M is the index of modulation, and f (t) is OOK modulation bipolar signal, Received signal strength s _t=R*H (0) P _t* M*f (t), R are the response gain constant of photodetector;

System noise than SNR is $\mathrm{SNR}=\frac{P_S}{P_{\mathrm{noise}}}=\frac{R^{2}H{\left(0\right)}^2{P}_t^2{M}^2\stackrel{\‾}{f{\left(t\right)}^2}}{P_{\mathrm{noise}}}---\left(10\right)$

When signal transmitting power, the index of modulation and modulation bipolar signal average power are stablized, received signal power P _sdirect ratio and H ², thus relevant to the distance of acceptance point, the light angle of departure, angle of light size to light source (0).

(2) multiple spot LED light source

In fig. 2, light source is multiple distribution type LED light sources, and receiving plane acceptance point (xr, yr, zr) place illumination is be the illumination sum of the i-th row jth row top light source acceptance point for this reason, pointolite array is the capable N row of L;

Acceptance point r (x, y, z) received signal power Ps is

$P_s(x,y,z)=R^2{H}^2\left(0\right)M^2\stackrel{\‾}{f^2\left(t\right)}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{P}_t(i,j)---\left(11\right)$

The signal to noise ratio snr of acceptance point r (x, y, z) is:

Receiving plane signal to noise ratio snr average is: wherein s is light-receiving area of plane s=max (x) * max (y), the length that max (x), max (y) are communication space and wide;

The degree of signal to noise ratio deviation average represents with standard deviation D:

$D=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\∫}}\underset{0}{\overset{\max \left(x\right)}{\∫}}(\frac{P_s(x,y)}{P_{\mathrm{noise}}}-\stackrel{\‾}{\mathrm{SNR}})\mathrm{dxdy}---\left(13\right)$

Standard deviation D is less, then light signal distributing homogeneity is better.

Highly for 0.85m accepts the optical signal property of plane as shown in Figure 5 under the design, normalization illuminance maximum 1, minimum value 0.32, variance rate d=(max (E)-min (E))/max (E) is 0.68, the standard deviation of receiving plane is 2.08%, and maximum signal to noise ratio is 6.93db, and minimum signal to noise ratio is-4.46db, corner, edge minimum value is less, and the space effective area that centre position illumination value is larger is larger.

Embodiment 2: first the method builds LED light source illumination patterns and the optical signal power distributed model of visible ray in underground coal mine working face, is uniformly distributed formula LED light source to underground coal mine working face cuboid communication space based on the constant power of edge power correction and carries out layout.Be uniformly distributed on the basis of light source at constant power, edge light source power is revised.In described structure underground coal mine working face, the LED light source illumination patterns of visible ray is identical with embodiment 1 with optical signal power distributed model.

Selected invention communication space is wide 4m, and the underground coal mine working face of long 20m, high 3m, the even square formation layout of the top design LED light source of hydraulic support as shown in Figure 4.

Designing concrete execution step of the present invention is:

Step 1: in FIG, when LED light source is a single point light source, determine that light source space coordinate position and launch point three dimensional space coordinate are (xs, ys, zs), optical receiver point central three-dimensional spatial coordinate location is (xr, yr, zr).

Step 2: the luminous intensity of point-source of light is in formula, Ir represents luminous flux d Φ and the ratio of light source in assigned direction dw angle.

Step 3: the distance d of light receiving area dA, the angle dw of optical receiver, light source and acceptance point and angle of light θ, between geometrical relationship be

d ²*dw＝dA*cosθ。(2)

Illuminance E in receiving plane, is defined as the luminous flux in unit are, namely

Formula (1), (2) substitute into formula (3) and obtain $E=\frac{I_r}{d^2}*\cos \mathrm{\θ}.---\left(4\right)$

Step 4: assuming that white light LEDs meets lambert's irradiation, LED luminous intensity

In formula: m=ln (1/2)/ln (cos φ _1/2), φ _1/2for the half-power angle of LED, can check in the LED property parameters that dispatches from the factory, LED type number is determined, parameter m just determines, and φ is the light angle of departure.

Formula (5) is substituted into formula (4), then illuminance

Underground coal mine working face LED light source is installed on hydraulic support, and adopt the mounting means in vertical and horizontal face, receiving plane is parallel to horizontal plane, and namely the top plane of LED light source is parallel with receiving plane, and now angle of light is equal with the light angle of departure, i.e. θ=φ.

Now, $\cos \mathrm{\θ}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}}.---\left(7\right)$

Then illuminance E is $E=\frac{m+1}{2\mathrm{\π}{d}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-x_s)}^2+{(y_r-y_s)}^2+{(z_r-z_s)}^2}}\right)}^{m+1}.---\left(8\right)$

Step 5: for LOS straight length in visible light communication system, luminous power is

H(w)＝H(0)e ^-jwτ

H (0) is channel DC current gain $H\left(0\right)=\frac{(m+1)A}{2\mathrm{\π}{d}^2}\cos \mathrm{\θ}*{\cos }^m\mathrm{\φ},---\left(9\right)$

In formula: A is the light receiving area of photodetector, τ is time delay.

Mean receiving power is P _r=P _th (0), wherein P _tfor the average transmit power of LED, suppose that LED transmits as p _t=P _t(1+M*f (t)), M is the index of modulation, and f (t) is OOK modulation bipolar signal, Received signal strength s _t=R*H (0) P _t* M*f (t), R are the response gain constant of photodetector.

System noise than SNR is $\mathrm{SNR}=\frac{P_S}{P_{\mathrm{noise}}}=\frac{R^{2}H{\left(0\right)}^2{P}_t^2{M}^2\stackrel{\‾}{f{\left(t\right)}^2}}{P_{\mathrm{noise}}}.---\left(10\right)$

Step 6: in visible light communication system, light source is multiple distribution type LED point-source of lights, pointolite array is the capable N row of L, and receiving plane acceptance point (xr, yr, zr) place illumination is it is the illumination sum of the i-th row jth row top light source acceptance point for this reason.

Step 7: acceptance point r (x, y, z) received signal power Ps is

$P_s(x,y,z)=R^2{H}^2\left(0\right)M^2\stackrel{\‾}{f^2\left(t\right)}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{P}_t(i,j).---\left(11\right)$

The signal to noise ratio snr of acceptance point r (x, y, z) is:

Receiving plane signal to noise ratio snr average is: wherein s is light-receiving area of plane s=max (x) * max (y), the length that max (x), max (y) are communication space and wide.

Step 8: the degree of signal to noise ratio deviation average represents with standard deviation D:

$D=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\∫}}\underset{0}{\overset{\max \left(x\right)}{\∫}}(\frac{P_s(x,y)}{P_{\mathrm{noise}}}-\stackrel{\‾}{\mathrm{SNR}})\mathrm{dxdy}.---\left(13\right)$

Standard deviation D is less, then light signal distributing homogeneity is better.

Step 9: devise coal mine work area constant power and be uniformly distributed formula LED light source layout.At wide 4m, the even square formation layout of the top design LED light source of the communication space hydraulic support of long 20m as shown in Figure 4, first space uniform split plot design is at equal intervals adopted to be divided into 5 small size square spaces, according to square array design light source point position, the spacing d=1m of adjacent two light source points, communication space height is 3m, and the height of light-receiving plane is 0.85m, and LED light source power is the great power LED intrinsic safety type light source of 5w.

Step 10: highly for 0.85m accepts the optical signal property of plane as shown in Figure 5 under the design, normalization illuminance maximum 1, minimum value 0.32, variance rate d=(max (E)-min (E))/max (E) is 0.68, the standard deviation of receiving plane is 2.08%, and maximum signal to noise ratio is 6.93db, and minimum signal to noise ratio is-4.46db, corner, edge minimum value is less, and the space effective area that centre position illumination value is larger is larger.

Step 11: along with acceptance point is near the both sides in tunnel during receiving plane illumination and signal to noise ratio distribute, illumination and signal to noise ratio reduce thereupon, the value of center, tunnel illumination and signal to noise ratio is all very large, in order to improve the uniformity of receiving plane further, the standard deviation proposed in the present invention based on edge power revised law minimizes method of adjustment, suppose that the LED light source that edge one encloses has identical transmitting power, other LED light source still adopts 5w high-power LED light source.

Step 12: pointolite array is the capable N row of L, and acceptance point r (x, y, z) received signal power Ps is:

$P_s(x,y,z)=R^2{H}^2\left(0\right)M^2\stackrel{\‾}{f^2\left(t\right)}\underset{j=1}{\overset{N}{\mathrm{\Σ}}}\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{P}_t(i,j)$

The degree that signal to noise ratio departs from its mean value represents with standard deviation D,

time, try to achieve P _tvalue be the performance number of edge light.

Step 13: as follows according to algorithm design program step:

1) arranging is P0 with y direction both sides of edges LED light source initial power in the x-direction, and power adjustment step size is λ=0.3.

2) receiving plane SNR and standard deviation D thereof is calculated, if standard deviation D < 0.01, EP (end of program), otherwise according to P=P0+ λ.

3) the 2nd step is repeated.

4) if standard deviation D is greater than 0.01, but D in variance computational process _n+1> D _n, power when namely standard deviation no longer reduces, then EP (end of program), no longer Modulating Power.

Step 14: as shown in Figure 6, between 5 ~ 20w, standard deviation reduces very soon with power increase for changed power and standard deviation variation relation, on 20w, standard deviation change is little.Through overpower adjustment, edge, tunnel LED light source power is 10W, now, the normalization Illumination Distribution of receiving plane as shown in Figure 7, normalization illumination maximum 1, minimum value 0.44, variance rate is 0.56, signal to noise ratio maximum 10.78db, minimum value 2.53db, standard deviation is 0.01, have clear improvement than the distribution of light sources performance of constant power, standard deviation reduces nearly one times, is only original 47%, achieves and to distribute better uniformity effects than constant power LED.

The above, can observe simulation result from Fig. 5 and Fig. 7, and the LED light source distributed layout receiving plane after overpower adjustment achieves better illumination uniformity.The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (4)

1. a coal mine work area visible light communication distributed light source method for arranging, it is characterized in that: be divided into top to be square some little communication space underground coal mine working face cuboid communication space, the mode that little communication space adopts each LED light source to be adjacent light source or border standoff distance equivalent is uniformly distributed high-power essential safe type white LED light source on hydraulic support, is namely uniformly distributed formula LED light source layout method at coal mine work area cuboid communication space constant power; On this basis, further correction edge light power, being spatially located at edge or four position, limit LED light source power so that photo-detector receiving plane signal to noise ratio deviation average mean square error is minimum for criterion adjusts visible light communication, is the formula that the is uniformly distributed LED light source layout method based on edge power revised law; Two kinds of modes are all to set up the Received signal strength model of structure coal mine work area light receiving surface for analysis foundation.

2. a kind of coal mine work area visible light communication distributed light source method for arranging according to claim 1, is characterized in that: described coal mine work area cuboid communication space constant power is uniformly distributed formula LED light source layout method:

Adopt homogeneous space segmentation mode be with coal mine work area hydraulic support top board composition plane be upper plane, with the length of hydraulic support top board for the length of side, become by coal mine work area visible light communication compartition top to be square some communication spaces, each communication space adopts non-uniform manner to distribute high-power essential safe type white LED light source;

Communication space illuminance after division is under the condition of 300 ~ 1500lx lighting criteria of meeting international standards organization establishment, in communication process, transmitting terminal blocks to receiving terminal clear, and LED light source power is enough large can receive LED light source information to meet receiving terminal receiving equipment photodetector, each LED light source is adjacent light source or border is uniformly distributed high-power essential safe type white LED light source in the mode that standoff distance is equivalent on hydraulic support.

3. a kind of coal mine work area visible light communication distributed light source method for arranging according to claim 1, is characterized in that: the described formula that the is uniformly distributed LED light source layout method based on edge power revised law:

Standard deviation based on edge power revised law minimizes method of adjustment, and the LED light source enclosed at edge one has identical transmitting power, and other LED light source still adopts identical high-power LED light source;

Pointolite array is the capable N row of L, and acceptance point r (x, y, z) received signal power Ps is:

In formula: x, y, z are three-dimensional space position coordinate, mean receiving power is P _r=P _th (0), wherein P _tfor the average transmit power of LED, suppose that LED transmits as p _t=P _t(1+M*f (t)), M is the index of modulation, and f (t) is OOK modulation bipolar signal, Received signal strength s _t=R*H (0) P _t* M*f (t), R are the response gain constant of photodetector;

H (0) is channel DC current gain m=ln (1/2)/ln (cos φ _1/2), φ _1/2for the half-power angle of LED, can check in the LED property parameters that dispatches from the factory, LED type number is determined, parameter m just determines, and φ is the light angle of departure, and A is the light receiving area of photodetector;

P _t(i, j) is the average transmit power of the i-th row j row point-source of light in array of source;

The degree that signal to noise ratio departs from its mean value represents with standard deviation D,

time, try to achieve P _tvalue be the performance number of edge light;

Wherein, s is overall light-receiving area of plane s=max (x) * max (y), the length that max (x), max (y) are communication space and wide;

Four limits or marginal position LED light source power is spatially located at for criterion adjusts visible light communication so that photo-detector receiving plane signal to noise ratio deviation average mean square error is minimum, make the optical signal receive power uniformity of receiving plane best, edge LED light source transmitting power is same adjustable value, and all the other LED light source power remain unchanged:

Step 1, add up the average signal-to-noise ratio of whole communication space at a certain receiving plane photodetector;

Step 2, photodetector is placed in below edge, communication space limit LED light source draws corresponding signal to noise ratio size, adjustment edge LED light source power, utilize the minimum power of PC judgement when signal to noise ratio departs from average signal-to-noise ratio error at tolerance interval, this power is set to this edge LED light source transmitting power;

Step 3, in due order rule adjust edge, four limits LED light source power respectively, and four drift angle LED light source power are by the adjustment of one of them edge power value;

The minimum power when signal to noise ratio departs from average signal-to-noise ratio error at tolerance interval comprises following steps to utilize PC to judge:

Step 1, edge LED light source initial gain value is arranged identical with non-edge LED light source;

Step 2, edge calculation LED light source underlying photoelectric detector receiving plane signal to noise ratio and with whole communication space average signal-to-noise ratio standard deviation;

Step 3, each fixed value that increases adjust edge LED light source performance number, and namely increase 0.3W, until calculate standard deviation to be less than acceptable error scope, namely error range is 0.01, then this value is set to edge LED light source performance number at every turn;

If step 4 standard deviation is greater than acceptable error scope all the time, will show that standard deviation is minimum, power when namely standard deviation no longer reduces is as edge LED light source power.

4. a kind of coal mine work area visible light communication distributed light source method for arranging according to claim 1, it is characterized in that: the Received signal strength model of described structure coal mine work area light receiving surface, be generalized to the snr computation model of the signal strength signal intensity of multiple spot LED light source receiving optical signals, light signal from the snr computation model of the signal strength signal intensity of single-point LED light source receiving optical signals, light signal;

The signal strength signal intensity of receiving optical signals, the snr computation model of light signal have single-point LED light source and multiple spot LED light source: (1) single-point LED light source

When LED light source is a single point light source, light source space coordinate position and launch point three dimensional space coordinate are (xs, ys, zs), optical receiver point central three-dimensional spatial coordinate location is (xr, yr, zr), Φ represents that LED sends the luminous flux of visible ray, and the luminous intensity of point-source of light is in formula, Ir represents luminous flux d Φ and the ratio of light source in assigned direction dw angle;

The distance d of light receiving area dA, the angle dw of optical receiver, light source and acceptance point and angle of light θ, between geometrical relationship be:

d ²*dw＝dA*cosθ (2)

Illuminance E in receiving plane, is defined as the luminous flux in unit are, namely

Formula (1), (2) substitute into formula (3) and obtain

The luminous intensity I of LED _rto specific LED production technology and encapsulate relevant, assuming that white light LEDs meets lambert's irradiation, LED luminous intensity

In formula: m=ln (1/2)/ln (cos φ _1/2), φ _1/2for the half-power angle of LED, can check in the LED property parameters that dispatches from the factory, LED type number is determined, parameter m just determines, and φ is the light angle of departure,

Formula (5) is substituted into formula (4), then illuminance

Underground coal mine working face LED light source is installed on hydraulic support, and adopt the mounting means in vertical and horizontal face, receiving plane is parallel to horizontal plane, and namely the top plane of LED light source is parallel with receiving plane, and now angle of light is equal with the light angle of departure, i.e. θ=φ;

Now,

Then illuminance E is

In visible light communication system, the light that receiving plane receives derives from two parts, and a part receives (line of sight) for straight line, derives from the direct irradiation of light source; A part is non-rectilinear reception (not line of sight), be mainly derived from illumination that light source sends to be mapped to light that ground, wall, bar etc. be reflected back and to be received detector and to receive, for LOS straight length, luminous power is: H (w)=H (0) e ^{-jw τ}

H (0) is channel DC current gain

In formula: A is the light receiving area of photodetector, τ is time delay;

Mean receiving power is P _r=P _th (0), wherein P _tfor the average transmit power of LED, suppose that LED transmits as p _t=P _t(1+M*f (t)), M is the index of modulation, and f (t) is OOK modulation bipolar signal, Received signal strength s _t=R*H (0) P _t* M*f (t), R are the response gain constant of photodetector;

System noise than SNR is

When signal transmitting power, the index of modulation and modulation bipolar signal average power are stablized, received signal power P _sdirect ratio and H ², thus relevant to the distance of acceptance point, the light angle of departure, angle of light size to light source (0);

(2) multiple spot LED light source

When light source is multiple distribution type LED light source, receiving plane acceptance point (xr, yr, zr) place illumination is be the illumination sum of the i-th row jth row top light source acceptance point for this reason, pointolite array is the capable N row of L;

Acceptance point r (x, y, z) received signal power Ps is:

The signal to noise ratio snr of acceptance point r (x, y, z) is:

Receiving plane signal to noise ratio snr average is: wherein s is light-receiving area of plane s=max (x) * max (y), the length that max (x), max (y) are communication space and wide;

The degree of signal to noise ratio deviation average represents with standard deviation D:

Standard deviation D is less, then light signal distributing homogeneity is better.