阅读说明：本技术 一种基于蝙蝠算法的室内可见光通信系统光源优化方法 (Indoor visible light communication system light source optimization method based on bat algorithm ) 是由 王平 黄丽 池思慧 牛书强 南犀 于 2020-06-08 设计创作，主要内容包括：本发明公开了一种基于蝙蝠算法的室内可见光通信系统光源优化方法,包括：构建可见光通信系统模型,分别得到接收机和发射机之间的信道直流增益H<Sub>los</Sub>(0)、反射信道增益H<Sub>nlos</Sub>(0)和接收机接收到的光照度E<Sub>r</Sub>及光功率P<Sub>r</Sub>；利用蝙蝠算法优化LED光源的位置和半功率角,改善室内可见光通信系统平面上接收光照度和光功率的分布均匀性。该方法不仅考虑了墙面的一次反射,同时不需要进行二次优化。经过本方法优化后的LED光源的位置和半功率角,平面上接收光功率的数值变得更加集中,分布变得更加平坦,角落与房间中心的功率偏差得到显著改善。(The invention discloses an indoor visible light communication system light source optimization method based on a bat algorithm, which comprises the following steps: constructing a visible light communication system model to respectively obtain the direct current gain H of a channel between a receiver and a transmitter los (0) Reflected channel gain H nlos (0) And the light level E received by the receiver r And optical power P r (ii) a The position and the half-power angle of the LED light source are optimized by utilizing a bat algorithm, and the distribution uniformity of the received light illumination and the light power on the plane of the indoor visible light communication system is improved. The method not only considers the primary reflection of the wall surface, but also does not need secondary optimization. The position and the half-power angle of the LED light source optimized by the method have the advantages that the numerical value of the receiving light power on the plane becomes more concentrated, the distribution becomes flatter, and the power deviation between the corner and the center of a room is obviously improved.)

1. A bat algorithm-based indoor visible light communication system light source optimization method is characterized by comprising the following steps:

1) constructing a visible light communication system model to respectively obtain the direct current gain H of a channel between a receiver and a transmitter_los(0) Reflected channel gain H_nlos(0) And the light level E received by the receiver_rAnd optical power P_r；

2) The position and the half-power angle of the LED light source are optimized by utilizing a bat algorithm, and the distribution uniformity of the received light illumination and the light power on the plane of the indoor visible light communication system is improved; specifically, the method comprises the following steps:

2a) initializing a bat population, and initializing and defining parameters related to each bat individual;

2b) construction with respect to optical power P_rThe fitness function of (1) the fitness function of (fitness),calculating the fitness value of each bat, finding the bat individual with the minimum fitness value and recording the current position of the bat individual;

2c) redefining a speed updating formula of a traditional bat algorithm, searching a pulse frequency formula and a position formula according to the redefined bat individual speed updating formula, and updating bat individual parameters;

2d) redefining a local search formula of the traditional bat algorithm, generating a random number rand, and determining the pulse rate r of the bat n_nIf rand > r_nGenerating a new position x according to the redefined local search formula_newThen go to the next step;

2e) determining the pulse loudness A of batn_nAnd determining the new position x separately_newAnd home position x_nFitness function of (x)_new) And fitness (x)_n) If rand < A_nAnd fitness (x)_new)＜fitness(x_n) Then the new position x generated in step 2d) is accepted_new(ii) a Then updating the pulse rate and pulse loudness;

2f) sorting the fitness values of all bats, finding out the minimum value and recording the position of the minimum value; judging whether the algorithm meets a termination condition, and if so, outputting a global optimal solution; otherwise, return to step 2 c).

2. The indoor visible light communication system light source optimization method based on bat algorithm as claimed in claim 1, wherein in step 1), the DC gain H between the receiver and the transmitter_los(0) Is represented as follows:

wherein S is the effective area of the receiver, d is the distance between the receiver and the transmitter, m is the Lambert coefficient,

the rectangular function model is as follows:

in the step 1), the gain H of the reflection channel between the receiver and the transmitter_nlos(0) Is represented as follows:

wherein D is₁Is the distance from the light source to the reflection point of the wall, D₂Is the distance from the reflection point to the receiver, p is the reflection coefficient of the wall, dA_wallIs the minor surface element of the reflecting surface, α is the incident angle of the light ray on the reflecting point of the wall, β is the emission angle of the reflecting point.

3. The method as claimed in claim 2, wherein in step 1), the illuminance E received by the receiver is determined according to the ambient light level_rComprises the following steps:

wherein E is_losIs the illuminance contributed by the direct link, E_nlosIs the illuminance contributed by the reflecting link, I₀Refers to the central luminous intensity of the LED light source, d is the distance between the receiver and the transmitter, m is the Lambert coefficient,

optical power P received by receiver_rComprises the following steps:

P_r＝∑[P_los+P_nlos]＝∑[H_los(0)P_t+∫_wallsP_tdH_nlos(0)](5)

wherein, P_losIs the optical power, P, contributed by the direct link_nlosIs the optical power, P, contributed by the reflective link_tIs the luminous power of the LED light source, H_los(0) And H_nlos(0) Which refer to the dc channel gain and the reflected channel gain between the receiver and the transmitter, respectively.

4. The indoor visible light communication system light source optimization method based on the bat algorithm as claimed in claim 1, wherein in the step 2), the illuminance and the optical power received by the receiver should satisfy the following formula:

wherein E is_r(R_j) Refers to the light level, P, received by the jth receiver on the receiving plane_r(R_j) Refers to the optical power received by the jth receiver on the receive plane.

5. The indoor visible light communication system light source optimization method based on bat algorithm as claimed in claim 1, wherein in the step 2a), the parameters related to each bat individual comprise the number N of bats, the search pulse frequency range [ Q ] Q_min,Q_max]Dimension D of solution, pulse amplitude A, pulse rate r, pulse amplitude attenuation coefficient a, pulse frequency enhancement factor b, maximum iteration number T, bat position coordinate x_nAnd bat velocity v_n。

6. The light source optimization method for an indoor visible light communication system based on a bat algorithm as claimed in claim 1, wherein in the step 2b), the fitness function fitness is constructed as follows:

where J denotes the total number of receive plane receivers,

7. The indoor visible light communication system light source optimization method based on the bat algorithm as claimed in claim 1, wherein in the step 2c), the redefined bat individual velocity updating formula, the search pulse frequency formula and the position formula are respectively:

Q_n＝Q_min-(Q_max-Q_min)β (9)

where K is the current iteration number, x_bestIn order to be the global best position,the velocity of bat n at times t and t +1, respectively, β being [0, 1%]Uniformly distributed random numbers;the position of bat n at times t and t +1, Q respectively_nSearch pulse frequency, Q, for batn_nBelong to [ Q_min,Q_max]。

8. The indoor visible light communication system light source optimization method based on the bat algorithm as claimed in claim 1, wherein in said step 2d), the bat individual local search update formula is redefined:

wherein x is_bestFor the global optimal position, K is the current iteration number, T represents the maximum iteration number, ζ ∈ [ -1,1 [ ]]Is a random number.

9. A bat algorithm based indoor visible light communication system light source optimization method according to claim 1, wherein in the step 2e), the pulse rate and pulse loudness are updated as follows:

wherein a is the attenuation coefficient of the pulse amplitude, b is the enhancement factor of the pulse frequency,

10. A bat algorithm based indoor visible light communication system light source optimization method according to claim 1, wherein for any 0 < a < 1, b > 0, the updated pulse rate and pulse loudness have the following trend:

wherein the content of the first and second substances,

Technical Field

The invention belongs to the technical field of visible light communication, and particularly relates to a method for optimizing the position and the half-power angle of an LED light source by using an improved bat algorithm, so that the received illuminance and the received light power distribution on a plane are more uniform.

Background

Visible Light Communication (VLC) technology is a promising wireless communication technology, and uses visible light emitted by LEDs as a carrier wave for communication. LEDs, which are fourth generation lighting, have a longer life and higher efficiency than light sources such as incandescent lamps, fluorescent lamps, etc., so that LEDs have been rapidly developed in recent years and gradually replace conventional lighting sources. LED-based VLC technology covers a wide range and communication activities can be performed in a lighted place. Compared with other wireless communication technologies, the VLC technology has high security performance, does not require spectrum authentication, does not generate electromagnetic interference, and thus can be deployed in many electromagnetically sensitive areas such as hospitals, mines, gas stations, and the like. In an indoor VLC system, the white light LED is not only an illumination light source but also a communication signal carrier. Therefore, in order to make the indoor VLC have no blind area, it should be ensured that the received light intensity and the received light power are sufficient at any position in the room. Different LED light source parameters and position coordinates may cause different received light power and received light illuminance distributions on the same plane. The fluctuation of the indoor illuminance and the received optical power can influence the comfort level of indoor senses and the fairness of communication, so that the parameters and the position coordinates of the LED are necessarily researched, and the indoor illuminance and the received optical power are distributed more uniformly.

300lx-1500lx is the range of illuminance requirements that needs to be met indoors. In the whole indoor VLC system, the illuminance emitted by a single LED is small, and the international lighting requirement cannot be met, so that a plurality of LED light sources are generally required to form an array and be distributed on an indoor ceiling. Meanwhile, if the indoor illuminance satisfies the required range, the uniformity of the distribution of the receiving plane illuminance also needs to be considered. Because the uniformly distributed illumination is beneficial to illumination and visual perception of indoor personnel. The receiving optical power is an important factor influencing the performance of the VLC system, and the uniformly distributed receiving optical power can not only ensure that the same service quality is provided for different users on the same receiving plane, but also improve the communication quality of the system. An appropriate LED light source position can provide a less fluctuating illuminance distribution and optical power distribution in the room, thereby improving the quality of illumination and communication at the receiving plane. In the position layout of the visible light source LEDs, two influencing factors generally need to be considered, one influencing factor is the overall arrangement mode of the LED light sources on the indoor ceiling, and the other influencing factor is the distance between the LED light sources and the distance between the edge LEDs and the wall. In addition, the half-power angle of the LED light source also affects the received light illuminance and the received light power of the VLC system. In general, to achieve a uniform illumination range, all LED light sources use the same wide half-power angle. However, in the communication system, since the incident angle of the optical signal from the distant LED is large at the receiving end, the signal power may be reduced, thereby causing the system performance to be degraded. To solve this problem, it is therefore necessary to consider optimizing the half-power angle of the LED light source.

It has been reported that much work has been done on the light source optimization problem of VLC systems. However, the current problems are:

1) some light source optimization methods do not take into account the effects of reflection;

2) some light source optimization needs secondary optimization;

the LED light source is significant to the VLC system in consideration of the fact that the VLC technology uses the white LED as a transmitting terminal, which can also provide convenient, fast, environment-friendly, and energy-saving communication services while satisfying the demand for illumination. And the position and parameters of the LED light source may affect the received light illuminance and received light power distribution of the communication system. Different LED light source parameters and positions may cause different optical power and illuminance distributions on the receiving plane. In an indoor VLC system, the uneven distribution of optical power and illumination may result in that different users on the same plane cannot enjoy the same quality of service, thereby affecting the fairness of communication. Therefore, research on optimizing the signal distribution of the VLC system is imperative, and equal service quality is provided for different indoor users.

Disclosure of Invention

The invention aims to provide an indoor visible light communication system light source optimization method based on an improved bat algorithm, and the distribution uniformity of received light illumination and received light power on a VLC system plane is improved by researching a light source optimization technology.

The invention is realized by the following technical scheme.

A bat algorithm-based indoor visible light communication system light source optimization method comprises the following steps:

1) constructing a visible light communication system model to respectively obtain the direct current gain H of a channel between a receiver and a transmitter_los(0) Reflected channel gain H_nlos(0) And the light level E received by the receiver_rAnd optical power P_r；

2) The position and the half-power angle of the LED light source are optimized by utilizing a bat algorithm, and the distribution uniformity of the received light illumination and the light power on the plane of the indoor visible light communication system is improved; specifically, the method comprises the following steps:

2a) initializing a bat population, and initializing and defining parameters related to each bat individual;

2b) construction with respect to optical power P_rThe fitness function fitness, calculating the fitness value of each bat, finding out the bat individual with the minimum fitness value and recording the current position of the bat individual;

2c) redefining a speed updating formula of a traditional bat algorithm, searching a pulse frequency formula and a position formula according to the redefined bat individual speed updating formula, and updating bat individual parameters;

2d) redefining a local search formula of the traditional bat algorithm, generating a random number rand, and determining the pulse rate r of the bat n_nIf rand > r_nGenerating a new position x according to the redefined local search formula_newThen go to the next step;

2e) determining the pulse loudness A of batn_nAnd determining the new position x separately_newAnd home position x_nFitness function of (x)_new) And fitness (x)_n) If rand < A_nAnd fitness (x)_new)＜fitness(x_n) Then the new position x generated in step 2d) is accepted_new(ii) a Then updating the pulse rate and pulse loudness;

2f) sorting the fitness values of all bats, finding out the minimum value and recording the position of the minimum value; judging whether the algorithm meets a termination condition, and if so, outputting a global optimal solution; otherwise, return to step 2 c).

The invention has the following advantages:

the invention provides an indoor visible light communication system light source optimization method based on an improved bat algorithm, which not only considers the primary reflection of a wall surface, but also does not need secondary optimization. In order to verify the effectiveness and universality of the algorithm, simulation experiments are respectively carried out on the LED light source rectangular layout model and the mixed layout model, and the simulation result shows that the method has good performance.

Drawings

FIG. 1 is a LOS link diagram;

FIG. 2 is a schematic view of an NLOS link;

FIG. 3a) is an original rectangular layout of LED light sources, and FIG. 3b) is an original hybrid layout of LED light sources;

FIG. 4 is a diagram of an original illuminance distribution under a rectangular layout;

FIG. 5 is a diagram of the original received optical power distribution under a rectangular layout;

FIG. 6 is a schematic view of a rectangular layout of light sources before and after optimization;

FIG. 7 is a diagram of a distribution of illumination intensities in a rectangular layout after optimization of light sources;

FIG. 8 is a diagram of received optical power distribution under a rectangular layout after optimization of the light sources;

FIG. 9 is a diagram of the original illuminance distribution under the hybrid layout;

fig. 10 is a diagram of the original received optical power distribution in the hybrid layout;

FIG. 11 is a schematic diagram of a pre-optimization and post-optimization LED light source hybrid layout;

FIG. 12 is a diagram illustrating a distribution of illumination intensity in a hybrid layout after optimization of light sources;

fig. 13 is a diagram of received optical power distribution under the hybrid layout after the light source is optimized.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following detailed description is further provided in conjunction with the accompanying drawings and the detailed description. The present embodiment is merely illustrative of the principles of the present invention and does not represent any limitation of the present invention.

The invention provides an indoor visible light communication system light source optimization method based on an improved bat algorithm, which comprises the following steps:

step 1, constructing a visible light communication system model, and respectively obtaining direct current gain H of a channel between a receiver and a transmitter_los(0) Reflected channel gain H_nlos(0) And the light level E received by the receiver_rAnd optical power P_r。

In an indoor visible light communication system model, an LED light source is used as a transmitter, and a photoelectric detector is used as a receiver. Depending on the way in which optical signals are transmitted, the communication links of VLC systems include direct Links (LOS) and diffuse links (Non-Line-of-Sight, NLOS), which are also called Non-direct links. In an LOS link, the direct channel gain between the receiver and the transmitter can be expressed as follows:

wherein S is the effective area of the receiver, d is the distance between the receiver and the transmitter, m is the Lambert coefficient,wherein, theta_1/2Is the half-power angle of the LED, theta is the emission angle relative to the vertical axis of the LED, psi is the receiving angle of the receiver, FOV is the angle of view of the receiver, T_sIs the gain of the optical filter, G_sIs the optical concentrator gain. rect (x) is a rectangular function model, which can be defined as:

in an NLOS link, the reflected channel gain between the receiver and the transmitter is as follows:

wherein D is₁Is the distance from the light source to the reflection point of the wall, D₂Is the distance from the reflection point to the PD,. rho.is the reflection coefficient of the wall, dA_wallIs the minor surface element of the reflecting surface, α is the incident angle of the light ray on the reflecting point of the wall, β is the emission angle of the reflecting point.

In VLC systems, the receiver receives a level of illumination E_rComprises the following steps:

wherein E is_losIs the illumination contributed by the LOS link, E_nlosLet us assume the illuminance, I, contributed by the NLOS link₀Refers to the central luminous intensity of the LED light source, d is the distance between the receiver and the transmitter, m is the Lambert coefficient,wherein, theta_1/2Is the half-power angle of the LED light source, theta is the emission angle relative to the vertical axis of the LED light source, psi is the receiving angle of the receiver, D₁Is the distance from the light source to the reflection point of the wall, D₂Is the distance from the reflection point to the receiver, p is the reflection coefficient of the wall, dA_wallIs the minor surface element of the reflecting surface, α is the incident angle of the light ray on the reflecting point of the wall, β is the emission angle of the reflecting point.

In VLC systems, the optical power P received by the receiver_rComprises the following steps:

wherein, P_losIs the optical power, P, contributed by the LOS link_nlosIs the optical power, P, contributed by the NLOS link_tIs the luminous power of the LED light source, H_los(0) And H_nlos(0) Which refer to the dc channel gain and the reflected channel gain between the receiver and the transmitter, respectively.

By analyzing the problem of light source optimization, it is pointed out that the position and half-power angle of the LED light source are important factors affecting the signal distribution, and therefore needs to be optimized.

And 2, optimizing the position and the half-power angle of the LED light source by using a bat algorithm, and improving the receiving light illumination and the light power distribution uniformity on the plane of the indoor visible light communication system.

The light source optimization is mainly to optimize the position and the half-power angle of the LED light source so that the illuminance and the optical power received by the receiver on the same receiving plane can satisfy the following formula as much as possible:

wherein E is_r(R_j) Refers to the light level, P, received by the jth receiver on the receiving plane_r(R_j) Refers to the optical power received by the jth receiver on the receive plane.

Wherein, optimizing the position and half-power angle of the LED light source by using the improved bat algorithm is obtained by the following steps:

2a) the bat population is initialized and parameters related to each bat individual should be initialized and defined. These parameters are the number of bats N, the search pulse frequency range Q_min,Q_max]Dimension D of solution, pulse amplitude A, pulse rate r, pulse amplitude attenuation coefficient a, pulse frequency enhancement factor b, maximum iteration number T, bat position coordinate x_nAnd bat velocity v_n。

2b) In the light source optimization, the optimization target is to obtain the received illuminance and the received optical power which are uniformly distributed in the indoor environment. In other words, it is desirable that all received light intensities and received light power fluctuations on the same receiving plane be minimized. In mathematics, the variance can measure the fluctuation degree of a sample, so that the variance of the received optical power is set as a fitness function of an algorithm; calculating the fitness value of each bat, and finding the optimal position of the bat.

The fitness function in the present invention is defined as:

wherein J represents the total number of receive plane receivers;

represents the average received optical power of the receiving plane; j refers to the jth receiver on the receiving plane, P_r(R_j) Refers to the optical power received by the jth receiver on the receive plane.

2c) And updating parameters of the bat. The bat individual speed of the traditional bat algorithm, the update formula of the search pulse frequency and the position are defined as follows:

Q_n＝Q_min-(Q_max-Q_min)β (9)

where K is the current iteration number and β is [0,1 ]]Uniformly distributed random numbers.

The position of bat n at times t and t +1, Q respectively_nSearch pulse frequency, Q, for batn_nBelong to [ Q_min,Q_max]，

Velocity, x, of bat n at times t and t +1, respectively_bestAs a global optimal position (solution) found so far, it is a solution obtained after comparing all N bat individuals.

In our experiment, we order Q according to the type of problem_min＝0，Q_max＝2。In order to accelerate the search rate of the algorithm and improve the performance of the system, the speed updating formula is redefined as:

2d) the method comprises the following steps Generating a random number rand, and determining the pulse rate r of the bat n_nIf rand > r_nGenerating a new position x according to the redefined local search formula_newAnd then goes to the next step. The local search update formula of the traditional bat algorithm is defined as:

x_new＝x_best+ζA^t(12)

wherein x is_bestAs a global optimum position, x_newRepresents the new location, ζ ∈ [ -1, obtained after performing a local search]Is a random number, A^tRefers to the average loudness of the population at time t. In order to deal with the increase of variables to be optimized, the bat individual local search updating formula is redefined:

wherein K is the current iteration frequency, and T represents the maximum iteration frequency.

2e) The method comprises the following steps Determining the pulse loudness A of batn_nAnd determining the new position x separately_newAnd home position x_nFitness function of (x)_new) And fitness (x)_n) If rand < A_nAnd fitness (x)_new)＜fitness(x_n) Then the new solution generated in step 2d) is accepted and the pulse rate and pulse loudness are updated according to the following equations:

wherein a is the pulse amplitude attenuation coefficientAnd b is a pulse frequency enhancement factor, specifically, a is a cooling coefficient similar to a cooling schedule in simulated annealing.

Is the pulse rate of batn at the initial instant,is the pulse rate of batn at time t +1,

the pulse loudness of bat n at time t and time t +1, respectively. For any 0 < a < 1, b > 0, equations (14) and (15) have the following trends:

wherein the content of the first and second substances,is the pulse rate of batn at time t. Where a is 0.9 and b is 0.9.

2f) The method comprises the following steps Firstly, sorting the fitness values of all bats, finding out the minimum value and recording the position of the minimum value; secondly, judging whether the algorithm meets a termination condition, and if so, outputting a global optimal solution; otherwise, return to step 2 c).

In order to verify the effectiveness and universality of the algorithm, simulation experiments are respectively carried out on the LED light source rectangular layout model and the mixed type layout model.

The correctness and advantages of the invention can be further illustrated by comparing the following theoretical results:

in the method, analog simulation verification is carried out through MATLAB.

Firstly, introducing a channel model of an indoor VLC system, analyzing the problem of light source optimization, and indicating that the position and half-power angle of an LED light source can influence the signal distribution uniformity of the system, so that the two factors need to be optimized; then, simulating and researching the performance of the proposed algorithm in an LED light source rectangular layout model; and finally, simulating and researching the performance of the proposed algorithm in an LED light source hybrid layout model.

Theoretical and simulation results

FIG. 1 shows a LOS link diagram; FIG. 2 shows a NLOS link diagram; fig. 3a) -3 b) show the original rectangular layout and the mixed layout of the LED light source. In fig. 3a), c denotes the distance between the LED light sources and the wall and l denotes the spacing between the LED light sources. In fig. 3b), R represents the radius of the annular LED light source, g represents the distance from the LED light sources at the four corners to the wall, and e represents the distance between the two middle LED light sources. Table 1 gives the parameters of the system simulation; table 2 gives the parameters after the rectangular layout of the LED light source is optimized; table 3 shows the parameters after the hybrid layout of LED light sources is optimized.

TABLE 1 simulation parameters table of system

TABLE 2 LED light source rectangular layout optimized parameters

TABLE 3 LED light source hybrid layout optimized parameters

Setting c to 1m and l to 1m is to optimize the distance between the LEDs and the wall and the interval between the LEDs in the rectangular layout of the front light respectively. Fig. 4 is a graph of the original luminance distribution under a rectangular layout. As can be seen from the figure, the raw received illuminance varies between 426.25lx and 1931.48lx, and the difference between the peak and the valley is 1505.23 lx. It can be seen from the figure that the fluctuation of the illuminance distribution on the receiving plane is very large under the layout, and the maximum value of the illuminance exceeds the value 1500lx specified by the international lighting organization. Fig. 5 is a diagram of the raw received optical power distribution in a rectangular layout. In fig. 5, the optical power on the receive plane fluctuates between-5.89 dBm and 0.67dBm, the average receive power is-1.56 dBm, and the receive power variance is 2.1871 dBm. From the simulation results, the received optical power distribution on the receiving plane is very uneven, and the power value gradually decreases from the center of the room to the periphery. Fig. 6 shows schematic diagrams of rectangular layout of light sources before and after optimization, wherein blue circles represent original LED array layout and red circles represent optimized LED array layout. Fig. 7 shows the distribution diagram of the illuminance of the rectangular layout after the light source is optimized. In fig. 7, the distribution of the received light illuminance optimized by the improved bat algorithm is between 489.81lx and 829.79lx, and the difference between the valley value and the peak value is 339.98 lx. The optimized received light illumination is within the 300lx-1500lx standard specified by the International Lighting organization. Fig. 8 shows a received optical power distribution diagram under the rectangular layout after the light source is optimized. In fig. 8, the received optical power optimized by the proposed algorithm fluctuates between-2.56 dBm and-1.69 dBm, the average value of the power is-2.03 dBm, and the variance of the received power is 0.0280 dBm. In conclusion, it can be known from the analysis that after the position and the half-power angle of the LED light source are optimized by the improved bat algorithm, the fluctuation of the received illuminance and the received optical power on the plane is significantly reduced, that is, the optimized system can realize more uniform signal distribution. Fig. 9 is a graph of the original luminance distribution in the hybrid layout. In the original hybrid light source layout model, the radius R of the LED light sources is 1m, the distance g between the LEDs at the corners and the wall is 1m, and the distance e between the two middle LED light sources is 1 m. In fig. 9, the illuminance of the receiving plane varies in a range from 398.51lx to 2417.96lx, and the maximum value and the minimum value of the illuminance differ by 2019.45 lx. The maximum value of the received light intensity far exceeds the range required by the international lighting organization, and the fluctuation is very large. Fig. 10 is a graph of the raw received optical power distribution in a hybrid layout. In fig. 10, the received power varies between-6.18 dBm and 1.65dBm on the plane, the mean of the received power is-1.46 dBm, and the variance of the received power is 3.3021 dBm. It can be known from these data analyses that, under the original hybrid layout model, the illuminance and the received optical power distribution on the system receiving plane fluctuate greatly, which is not favorable for the sensory comfort of indoor personnel and the fairness of system communication. Fig. 11 is a schematic diagram of a mixed type layout of LED light sources before and after optimization, wherein a blue circle represents an original layout and a red circle represents an optimized layout. Fig. 12 shows the distribution diagram of the illuminance of the hybrid layout after the light source is optimized. In fig. 12, the light source is optimized by the improved bat algorithm, the fluctuation range of the received light illumination is 544.08 lx-870.51 lx, and the difference between the valley value and the peak value of the fluctuation is 326.43 lx. Compared with the illumination before optimization, the illumination intensity of the received light after optimization is within the range required by the international lighting organization, and the fluctuation range is obviously reduced. Fig. 13 shows a received optical power distribution diagram under the hybrid layout after the light source is optimized. In FIG. 13, the optical power received at the optimized source plane varies between-2.63 dBm and-1.63 dBm, with a mean of-2.06 dBm and a variance of 0.0333 dBm. According to the analysis, after the position and the half-power angle of the LED light source are optimized by the algorithm, the value of the received light power on the plane becomes more concentrated, the distribution becomes flatter, and the power deviation between the corner and the center of the room is obviously improved.

The present invention is not limited to the above-mentioned embodiments, and based on the technical solutions disclosed in the present invention, those skilled in the art can make some substitutions and modifications to some technical features without creative efforts according to the disclosed technical contents, and these substitutions and modifications are all within the protection scope of the present invention.