CN103401611A - Method for arranging visible light communication distributed light sources of coal mine working face - Google Patents

Abstract

The invention relates to a method for arranging visible light communication distributed light sources of a coal mine working face, and belongs to a method for arranging light sources of the coal mine working face. On the basis of providing a model of visible light LED light source illumination distribution and light signal power distribution in the underground coal mine working face, a cuboid-shaped communication space of the coal mine working face is divided into a plurality of small communication spaces with the top parts being square. High-power intrinsically safe white light LED light sources are uniformly distributed on a hydraulic support in the small communication space in such a mode that the distance between each of the LED light source and an adjacent light source or a boundary is identical. The light source signal intensity of a receiving plane is enabled to be the optimal through a solution based on correcting the edge light source power. The model of the equal-power uniformly distributed LED light sources of the underground coal mine working face ensures uniform coverage of wireless light signals of the receiving plane, and can meet double requirements of communication and lighting of the LED light sources in the coal mine working face; the receiving performance is ensured through further correcting the light source power at the edges or the four side positions, and the standard deviation of the light signals of the receiving plane is enabled to reduce to about 50% of that of the original.

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 by means of the wired and wireless communication mode that combines the real time communication that down-hole is aboveground, along with the driving face communication space of coal-winning machine constantly changes, it is wired very inconvenient to lay, and radio communication is the optimal communication mode.All there are certain limitation in traditional radio leakage, Personal Handyphone System, CDMA, the WiFi communication technology 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 present up-to-date wireless communication technology, these several wireless communication technologys are all by airwave communication, the Mine Communication space is the confined space, during radio wave transmissions, the multipath phenomenon is serious, guarantee data accuracy in order to overcome the multipath phenomenon, the complexities such as signal modulation system, communication equipment increase greatly, simultaneously, data rate is limited in 100Mbps, can't reach high data rate.

visible light communication is simple by the light-emitting diode transceiver, transmission speed is fast, the error rate is low, a little less than the multipath phenomenon, illumination is provided in the time of communication, simultaneously, the visible light communication space of colliery mining face under mine is compared strong background noises such as thering is no sunlight and is disturbed with the ground communication space, the light source background noise is little, light source is exactly signal source, simultaneously a little less than the albedo of rib to visible light of black, energy of reflection light is about 5% left and right of incident light illumination, the light signal that arrives optical receiver after the certain transmission range decay of air medium almost can be ignored, visible light communication system is to solve a kind of efficient communication technology of Underground Wireless Communication in Coal Mine.

In visible light communication system, intensity modulated---the mode of direct-detection realizes data communication in many employings, the lightwave signal that direct-detection is sent by photodetector direct detection LED, thereby to make communication efficiency reach optimum, must make the illumination signal intensity that distributes on same level less, be that the distribute even effect of more evenly communicating by letter of same level light signal is better, thereby reduce the requirement of communications receiving equipment, make communications receiving equipment be 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 source layout that has that OMEGA engineering research team proposes, the Nakagawa research team of Japan keio university is for the convenience of Project Realization, grouping LED array source layout has been proposed, the people such as Wang Zixiong of Nanyang Technological University in 2012 have proposed the distribution pattern of 12+4, 12 LED light sources are uniformly distributed on circumference take r as radius, 4 LED light sources are distributed in 4 corners of square communication space, thereby 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. CN1316835A, reliably a kind of receiving equipment and the transmitting apparatus of sending and receiving high-speed optical signal have been provided, and the communication system that adopts this equipment, wherein transmitting apparatus uses white light LED array, as 4 row 4 row LED array, all LED powers are identical, be used in office or family illumination with communicate by letter.Nanjing Univ. of Posts and Telecommunications's application in 2012 is based on the indoor visible light communication system process of the precoding MU-MIMO of white light LEDs signal precoding, adopt again LED array to send light signal, receiving circuit is through the output of signal output processing unit, eliminate multi-user interference with this, effectively reduce the complexity of receiving terminal, do not mention the concrete form of LED array.

The problem that exists in more design method is: the one, and the research that distributes for LED light source in visible light communication both at home and abroad all is limited to the research 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, and the hydraulic support top board layout in narrow and small working face space is difficult for realizing.The 2nd, LED light source used is the constant power light source, reach by changing the LED layout uniformity effect that improves the light receiving surface signal, this method not only effect is limited, and can not be for difform communication space, and tool is not general and complicated in the enforcement of coal mine work area change source layout.

Summary of the invention

Purpose 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 can effectively be applicable to the hydraulic support top board layout in narrow and small working face space.Solve complicated difficult enforcement of research method that in present visible light communication, LED light source distributes, be not suitable for the problem of mine working face layout.

For achieving the above object, technical scheme of the present invention is: it is square some little communication space that colliery mining face under mine cuboid communication space is divided into top, little communication space adopts each LED light source to be adjacent the mode that light source or border standoff distance be equal to and be uniformly distributed high-power essential safe type white LED light source on hydraulic support, namely at coal mine work area cuboid communication space constant power, is uniformly distributed formula LED light source layout method; On this basis, further revise edge light power, adjust the visible light communication space take photo-detector receiving plane signal to noise ratio deviation average mean square error minimum as criterion and be positioned at edge or four position, limit LED light source power, be the formula that the is uniformly distributed LED light source layout method based on edge power correction method; Dual mode all builds the reception signal model of coal mine work area light receiving surface as analysis foundation take foundation.

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

Adopting mode that homogeneous space is cut apart is take plane that coal mine work area hydraulic support top board forms as upper plane, take the length of hydraulic support top board as the length of side, it is square some communication spaces that coal mine work area visible light communication space segmentation is become top, and each communication space adopts the even mode high-power essential safe type white LED light source that distributes;

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

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

Proposed in the present invention to minimize method of adjustment based on the standard deviation of edge power correction method, the LED light source of one circle has identical transmitting power at edge, 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

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

The degree that signal to noise ratio departs from its mean value represents with standard deviation D, $D=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\∫}}\underset{0}{\overset{\max \left(x\right)}{\∫}}(\frac{P_s(x,y)}{P_{\mathrm{noise}}}-\stackrel{\‾}{\mathrm{SNR}})\mathrm{dxdy}.$

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

Adjust the visible light communication space take photo-detector receiving plane signal to noise ratio deviation average mean square error minimum as criterion and be positioned at four limits or marginal position LED light source power, make the light signal received 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, the whole communication space of statistics are at the average signal-to-noise ratio of a certain receiving plane photodetector;

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

Step 3, rule is adjusted respectively edge, four limits LED light source power in due order, and four drift angle LED light source power are adjusted by one of them edge performance number;

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

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

Step 2, edge calculation LED light source below photodetector 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 at every turn, until calculate standard deviation less than the acceptable error scope, namely error range is 0.01, this value is made as edge LED light source performance number;

If step 4 standard deviation, all the time greater than the acceptable error scope, will draw the standard deviation minimum, the 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, simplify the complexity of optical communication receiving equipment, studied colliery mining face under mine LED light source illumination patterns and optical signal power distributed model.The reception signal 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 signal strength signal intensity of single-point LED light source receiving optical signals, the snr computation model of light signal;

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

(1) single-point LED light source

When LED light source was a single point light source, the light source space coordinate position was that the launch point three dimensional space coordinate is (xs, ys, zs), three dimensional space coordinate position, optical receiver point center is (xr, yr, zr), Φ represents that LED sends the luminous flux of visible light, and the luminous intensity of point-source of light is

In formula, Ir represents luminous flux d Φ and the ratio of light source on assigned direction dw angle.

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

d ²*dw=dA*cosθ （2）

Illuminance E on receiving plane, be defined as the luminous flux on unit are, namely

Formula (1), (2) substitution formula (3) $E=\frac{{\mathrm{<figure-callout\; id="2"\; label="I\; r\; d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">I</figure-callout>}}_r}{d^{}}*\cos \mathrm{\&theta;}---\left(4\right)$

The luminous intensity I of LED _rRelevant with encapsulation to specific LED production technology, suppose that white light LEDs meets lambert's irradiation, the LED luminous intensity $I_r=\frac{(m+1)}{2\mathrm{\&pi;}}*{\cos }^m\mathrm{\&phi;},---\left(5\right)$

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, the LED model is definite, and parameter m is just definite, and φ is the light angle of departure.

With formula (5) substitution formula (4), illuminance $E=\frac{(m+1)}{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;}---\left(6\right)$

Colliery mining face under mine LED light source is installed on hydraulic support, adopts the mounting means of vertical and horizontal face, and receiving plane is parallel to horizontal plane, and namely the plane, top of LED light source is parallel with receiving plane, and this moment, angle of light equated with the light angle of departure, i.e. θ=φ;

At this moment, $\cos \mathrm{\&theta;}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}---\left(7\right)$

Illuminance E is $E=\frac{m+1}{{2\mathrm{\&pi;d}}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}\right)}^{m+1}---\left(8\right)$

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

H(w)＝H(0)e ^-jwτ

，

H (0) is the channel DC current gain $H\left(0\right)\frac{(m+1)A}{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;},---\left(9\right)$

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

Mean receiving power is P _r=P _tH (0), wherein P _t, for 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, f (t), for OOK modulation bipolar signal, receives signal s _t=R*H (0) P _t* M*f (t), R is the response gain constant of photodetector;

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

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(0), thus relevant to the distance of acceptance point, the light angle of departure, angle of light size to light source.

(2) multiple spot LED light source

When light source was a plurality of distribution type LED light source, receiving plane acceptance point (xr, yr, zr) was located illumination and is

Be the capable j row of the i top light source illumination sum of 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

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

The signal to noise ratio snr of acceptance point r (x, y, z) is: $\mathrm{SNR}(x,y,z)=\frac{P_s}{P_{\mathrm{noise}}}---\left(12\right)$

Receiving plane signal to noise ratio snr average is: $\stackrel{\&OverBar;}{\mathrm{SNR}}=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\&Integral;}}\underset{0}{\overset{\max \left(x\right)}{\&Integral;}}\frac{P_s(x,y)}{P_{\mathrm{noise}}}\mathrm{dxdy},$ Wherein S is light-receiving area of plane S=max (x) * max (y), and max (x), max (y) are the length of communication space and wide;

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

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

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

Adopt beneficial effect and the advantage of such scheme as follows:

(1) constant power is uniformly distributed the formula LED light source, use the even square formation distributed layout visible light communication light sources such as LED light source, guaranteed that receiving plane wireless optical signal intensity covers uniformity, can realize communication and illumination double duty, simply be easy to realize than present layout method, and be applicable to very formalism optical communication space of colliery mining face under mine.

(2) based on the formula that the is uniformly distributed LED light source design optimization method of edge power correction method, adopt receiving plane signal to noise ratio deviation average minimum mean-squared error criterion to adjust the transmitting power of edge LED light source, make in the situation that not need to change the light signal received power uniformity of source layout's receiving plane best, have 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 50% original left and right.Be easy to realize to have generality than the inhomogeneity method that reaches at present raising light receiving surface signal by changing the LED layout, be applicable to the communication space of difformity or layout, and implement simple.

Description of drawings

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

Fig. 2 is a plurality of LED point-source of light irradiation schematic diagram of the present invention.

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

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

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

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

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

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

Embodiment

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

Build the reception signal model of coal mine work area light receiving surface, the reception signal 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; It is square some little communication space that colliery mining face under mine cuboid communication space is divided into top, and little communication space adopts each LED light source to be adjacent the mode that light source or border standoff distance be equal to and be uniformly distributed high-power essential safe type white LED light source on hydraulic support; And revise edge light power, namely take photo-detector receiving plane signal to noise ratio deviation average mean square error minimum as criterion, adjust the visible light communication space and be positioned at edge or four position, limit LED light source power.Make the light signal received 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, the work face length is tens meters and arrives hundreds of rice, wide and high is several meters to tens meters, the 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 the receiving terminal clear, and LED light source power enough can receive LED light source information to meet receiving terminal receiving equipment photodetector greatly, and concrete length is not limit.

Embodiment 1: at first the method builds LED light source illumination patterns and the optical signal power distributed model of visible light in the mining face under mine of colliery, colliery mining face under mine cuboid communication space constant power is uniformly distributed the formula LED light source carries out layout.

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

The mode that described employing homogeneous space is cut apart is take plane that coal mine work area hydraulic support top board forms as upper plane, take the length of hydraulic support top board as the length of side, it is square some communication spaces that coal mine work area visible light communication space segmentation is become top, it is high-power that each communication space adopts even mode to distribute, and adopts 5W essential safe type white LED light source;

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

Design the 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, at first adopt uniformly-spaced space uniform split plot design to be divided into 5 small size square spaces, according to square array design light source point position, between adjacent two light source points apart from d=1m, the communication space height is 3m, and the height on light-receiving plane is 0.85m, and LED light source power is the great power LED intrinsic safety type light source of 5w.

The reception signal 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 signal strength signal intensity of single-point LED light source receiving optical signals, the snr computation model of light signal;

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

(1) single-point LED light source

In Fig. 1, when LED light source was a single point light source, the light source space coordinate position was that the launch point three dimensional space coordinate is (xs, ys, zs), three dimensional space coordinate position, optical receiver point center is (xr, yr, zr), Φ represents that LED sends the luminous flux of visible light, and the luminous intensity of point-source of light is

In formula, Ir represents luminous flux d Φ and the ratio of light source on assigned direction dw angle.

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

d ²*dw=dA*cosθ （2）

Illuminance E on receiving plane, be defined as the luminous flux on unit are, namely

Formula (1), (2) substitution formula (3) $E=\frac{I_r}{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}*\cos \mathrm{\&theta;}---\left(4\right)$

The luminous intensity I of ED _rRelevant with encapsulation to specific LED production technology, suppose that white light LEDs meets lambert's irradiation, the LED luminous intensity $I_r=\frac{(m+1)}{2\mathrm{\&pi;}}*{\cos }^m\mathrm{\&phi;},---\left(5\right)$

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, the LED model is definite, and parameter m is just definite, and φ is the light angle of departure.

With formula (5) substitution formula (4), illuminance $E=\frac{(m+1)}{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;}---\left(6\right)$

Colliery mining face under mine LED light source is installed on hydraulic support, adopts the mounting means of vertical and horizontal face, and receiving plane is parallel to horizontal plane, and namely the plane, top of LED light source is parallel with receiving plane, and this moment, angle of light equated with the light angle of departure, i.e. θ=φ;

At this moment, $\cos \mathrm{\&theta;}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}---\left(7\right)$

Illuminance E is $E=\frac{m+1}{{2\mathrm{\&pi;d}}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}\right)}^{m+1}---\left(8\right)$

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

H(w)＝H(0)e ^-jwτ

，

H (0) is the channel DC current gain $H\left(0\right)\frac{(m+1)A}{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;},---\left(9\right)$

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

Mean receiving power is P _r=P _tH (0), wherein P _t, for 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, f (t), for OOK modulation bipolar signal, receives signal s _t=R*H (0) P _t* M*f (t), R is the response gain constant of photodetector;

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

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(0), thus relevant to the distance of acceptance point, the light angle of departure, angle of light size to light source.

(2) multiple spot LED light source

In Fig. 2, light source is a plurality of distribution type LED light sources, and receiving plane acceptance point (xr, yr, zr) is located illumination and is

Be the capable j row of the i top light source illumination sum of 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

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

The signal to noise ratio snr of acceptance point r (x, y, z) is: $\mathrm{SNR}(x,y,z)=\frac{P_s}{P_{\mathrm{noise}}}---\left(12\right)$

Receiving plane signal to noise ratio snr average is: $\stackrel{\&OverBar;}{\mathrm{SNR}}=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\&Integral;}}\underset{0}{\overset{\max \left(x\right)}{\&Integral;}}\frac{P_s(x,y)}{P_{\mathrm{noise}}}\mathrm{dxdy},$ Wherein S is light-receiving area of plane S=max (x) * max (y), and max (x), max (y) are the length of communication space and wide;

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

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

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

The optical signal property of highly accepting plane for 0.85m under the design as shown in Figure 5, normalization illuminance maximum 1, minimum value 0.32, (max (E)-min (E))/max (E) is 0.68 to variance rate d=, 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, four jiaos, edge minimum value is less, and the space effective area that the centre position illumination value is larger is larger.

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

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

Designing concrete execution step of the present invention is:

Step 1: in Fig. 1, when LED light source is a single point light source, determine that the light source space coordinate position is that the launch point three dimensional space coordinate is (xs, ys, zs), three dimensional space coordinate position, optical receiver point center 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 on assigned direction dw angle.

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

d ²*dw=dA*cosθ。（2）

Illuminance E on receiving plane, be defined as the luminous flux on unit are, namely

Formula (1), (2) substitution formula (3) $E=\frac{I_r}{{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}*\cos \mathrm{\&theta;}.---\left(4\right)$

Step 4: the supposition white light LEDs meets lambert's irradiation, the LED luminous intensity $I_r=\frac{(m+1)}{2\mathrm{\&pi;}}*{\cos }^m\mathrm{\&phi;},---\left(5\right)$

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, the LED model is definite, and parameter m is just definite, and φ is the light angle of departure.

With formula (5) substitution formula (4), illuminance $E=\frac{(m+1)}{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;}.---\left(6\right)$

Colliery mining face under mine LED light source is installed on hydraulic support, adopts the mounting means of vertical and horizontal face, and receiving plane is parallel to horizontal plane, and namely the plane, top of LED light source is parallel with receiving plane, and this moment, angle of light equated with the light angle of departure, i.e. θ=φ

。

At this moment, $\cos \mathrm{\&theta;}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}.---\left(7\right)$

Illuminance E is $E=\frac{m+1}{{2\mathrm{\&pi;d}}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}\right)}^{m+1}.---\left(8\right)$

Step 5: for LOS direct-view path in visible light communication system, luminous power is

H(w)＝H(0)e ^-jwτ

，

H (0) is the channel DC current gain $H\left(0\right)\frac{(m+1)A}{{2\mathrm{\&pi;<figure-callout\; id="2"\; label="d"\; filenames="HDA00003454546000012.png,HDA00003454546000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;},---\left(9\right)$

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

Mean receiving power is P _r=P _tH (0), wherein P _t, for 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, f (t), for OOK modulation bipolar signal, receives signal s _t=R*H (0) P _t* M*f (t), R is the response gain constant of photodetector.

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

Step 6: in visible light communication system, light source is a plurality of distribution type LED point-source of lights, and pointolite array is the capable N row of L, and receiving plane acceptance point (xr, yr, zr) is located illumination and is

It is the capable j row of the i top light source illumination sum of acceptance point for this reason.

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

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

The signal to noise ratio snr of acceptance point r (x, y, z) is: $\mathrm{SNR}(x,y,z)=\frac{P_s}{P_{\mathrm{noise}}}.---\left(12\right)$

Receiving plane signal to noise ratio snr average is: $\stackrel{\&OverBar;}{\mathrm{SNR}}=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\&Integral;}}\underset{0}{\overset{\max \left(x\right)}{\&Integral;}}\frac{P_s(x,y)}{P_{\mathrm{noise}}}\mathrm{dxdy},$ Wherein S is light-receiving area of plane S=max (x) * max (y), and max (x), max (y) are the length of communication space and wide.

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

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

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

Step 9: designed the 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, at first adopt uniformly-spaced space uniform split plot design to be divided into 5 small size square spaces, according to square array design light source point position, between adjacent two light source points apart from d=1m, the communication space height is 3m, and the height on 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: the optical signal property of highly accepting plane for 0.85m under the design as shown in Figure 5, normalization illuminance maximum 1, minimum value 0.32, (max (E)-min (E))/max (E) is 0.68 to variance rate d=, 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, four jiaos, edge minimum value is less, and the space effective area that the centre position illumination value is larger is larger.

Step 11: during receiving plane illumination and signal to noise ratio distribute along with the both sides of acceptance point near tunnel, 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 further to improve the uniformity of receiving plane, proposed in the present invention to minimize method of adjustment based on the standard deviation of edge power correction method, the LED light source of supposing edge one circle has identical transmitting power, and other LED light source still adopts the 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

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

The degree that signal to noise ratio departs from its mean value represents with standard deviation D, $D=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\&Integral;}}\underset{0}{\overset{\max \left(x\right)}{\&Integral;}}(\frac{P_s(x,y)}{P_{\mathrm{noise}}}-\stackrel{\&OverBar;}{\mathrm{SNR}})\mathrm{dxdy}.$

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

Step 13: as follows according to the 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 it is λ=0.3 that power is adjusted step-length.

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

3) repeated for the 2nd step.

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

Step 14: as shown in Figure 6, between 5～20w, standard deviation reduces very soon with increased power for power variation and standard deviation variation relation, and on 20w, standard deviation changes little.Through the overpower adjustment, edge, tunnel LED light source power is 10W, at this moment, 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, distribution of light sources performance than constant power has clear improvement, standard deviation has reduced nearly one times, is only original 47%, has obtained the better uniformity effect that distributes than constant power LED.

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

Claims (4)

1. coal mine work area visible light communication distributed light source method for arranging, it is characterized in that: it is square some little communication space that colliery mining face under mine cuboid communication space is divided into top, little communication space adopts each LED light source to be adjacent the mode that light source or border standoff distance be equal to and be uniformly distributed high-power essential safe type white LED light source on hydraulic support, namely at coal mine work area cuboid communication space constant power, is uniformly distributed formula LED light source layout method; On this basis, further revise edge light power, adjust the visible light communication space take photo-detector receiving plane signal to noise ratio deviation average mean square error minimum as criterion and be positioned at edge or four position, limit LED light source power, be the formula that the is uniformly distributed LED light source layout method based on edge power correction method; Dual mode all builds the reception signal model of coal mine work area light receiving surface as analysis foundation take foundation.

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

Adopting mode that homogeneous space is cut apart is take plane that coal mine work area hydraulic support top board forms as upper plane, take the length of hydraulic support top board as the length of side, it is square some communication spaces that coal mine work area visible light communication space segmentation is become top, and each communication space adopts the even mode high-power essential safe type white LED light source that distributes;

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

Standard deviation based on edge power correction method minimizes method of adjustment, and the LED light source of one circle has identical transmitting power at edge, 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

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

The degree that signal to noise ratio departs from its mean value represents with standard deviation D, $D=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\&Integral;}}\underset{0}{\overset{\max \left(x\right)}{\&Integral;}}(\frac{P_s(x,y)}{P_{\mathrm{noise}}}-\stackrel{\&OverBar;}{\mathrm{SNR}})\mathrm{dxdy};$

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

Adjust the visible light communication space take photo-detector receiving plane signal to noise ratio deviation average mean square error minimum as criterion and be positioned at four limits or marginal position LED light source power, make the light signal received 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, the whole communication space of statistics are at the average signal-to-noise ratio of a certain receiving plane photodetector;

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

Step 3, rule is adjusted respectively edge, four limits LED light source power in due order, and four drift angle LED light source power are adjusted by one of them edge performance number;

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

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

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

Step 3, increase fixed value at every turn and adjust edge LED light source performance number, namely increase 0.3W at every turn, until calculate standard deviation less than the acceptable error scope, namely error range is 0.01, this value is made as edge LED light source performance number;

If step 4 standard deviation, all the time greater than the acceptable error scope, will draw the standard deviation minimum, the 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 reception signal 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 signal strength signal intensity of single-point LED light source receiving optical signals, the snr computation model of light signal;

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

(1) single-point LED light source

When LED light source was a single point light source, the light source space coordinate position was that the launch point three dimensional space coordinate is (xs, ys, zs), three dimensional space coordinate position, optical receiver point center is (xr, yr, zr), Φ represents that LED sends the luminous flux of visible light, and the luminous intensity of point-source of light is

In formula, Ir represents luminous flux d Φ and the ratio of light source on assigned direction dw angle.

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

d ²*dw=dA*cosθ （2）

Illuminance E on receiving plane, be defined as the luminous flux on unit are, namely

Formula (1), (2) substitution formula (3) $E=\frac{I_r}{d^2}*\cos \mathrm{\&theta;}---\left(4\right)$

The luminous intensity I of LED _rRelevant with encapsulation to specific LED production technology, suppose that white light LEDs meets lambert's irradiation, the LED luminous intensity $I_r=\frac{(m+1)}{2\mathrm{\&pi;}}*{\cos }^m\mathrm{\&phi;},---\left(5\right)$

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, the LED model is definite, and parameter m is just definite, and φ is the light angle of departure.

With formula (5) substitution formula (4), illuminance $E=\frac{(m+1)}{{2\mathrm{\&pi;d}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;}---\left(6\right)$

Colliery mining face under mine LED light source is installed on hydraulic support, adopts the mounting means of vertical and horizontal face, and receiving plane is parallel to horizontal plane, and namely the plane, top of LED light source is parallel with receiving plane, and this moment, angle of light equated with the light angle of departure, i.e. θ=φ;

At this moment, $\cos \mathrm{\&theta;}=\frac{|z_r-z_s|}{d}=\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}---\left(7\right)$

Illuminance E is $E=\frac{m+1}{{2\mathrm{\&pi;d}}^2}{\left(\frac{|z_r-z_s|}{\sqrt{{(x_r-y_r)}^2+{(y_r-y_r)}^2+{(z_r-z_r)}^2}}\right)}^{m+1}---\left(8\right)$

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

H(w)＝H(0)e ^-jwτ

，

H (0) is the channel DC current gain $H\left(0\right)\frac{(m+1)A}{{2\mathrm{\&pi;d}}^2}\cos \mathrm{\&theta;}*{\cos }^m\mathrm{\&phi;},---\left(9\right)$

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

Mean receiving power is P _r=P _tH (0), wherein P _t, for 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, f (t), for OOK modulation bipolar signal, receives signal s _t=R*H (0) P _t* M*f (t), R is the response gain constant of photodetector;

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

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(0), thus relevant to the distance of acceptance point, the light angle of departure, angle of light size to light source.

(2) multiple spot LED light source

When light source was a plurality of distribution type LED light source, receiving plane acceptance point (xr, yr, zr) was located illumination and is

Be the capable j row of the i top light source illumination sum of 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

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

The signal to noise ratio snr of acceptance point r (x, y, z) is: $\mathrm{SNR}(x,y,z)=\frac{P_s}{P_{\mathrm{noise}}}---\left(12\right)$

Receiving plane signal to noise ratio snr average is: $\stackrel{\&OverBar;}{\mathrm{SNR}}=\frac{1}{s}\underset{0}{\overset{\max \left(y\right)}{\&Integral;}}\underset{0}{\overset{\max \left(x\right)}{\&Integral;}}\frac{P_s(x,y)}{P_{\mathrm{noise}}}\mathrm{dxdy},$ Wherein S is light-receiving area of plane S=max (x) * max (y), and max (x), max (y) are the length of communication space and wide;

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

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

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

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