A method for optimizing light source layout of an indoor visible light communication system

Abstract

The application discloses a light source layout optimization method for an indoor visible light communication system, and comprises the following steps: determining the area of a sub-region and an optimization sequence according to the distance from the geometric center of the sub-region to the geometric center of a global region, and performing sub-region division; mapping the influence of a light source in a post-optimization sub-region as the influence of a light source at the central position of the global region on each sub-region according to the sub-region division sequence, and using different compensation factors to simulate the influence on different sub-regions; and performing single light source position optimization on the sub-regions with the distance parameter distribution uniformity as the target, so as to further improve the optimization efficiency.

Description

Technical Field

[0001] This application relates to the field of optical communication technology, and specifically to a method for optimizing the layout of light sources in an indoor visible light communication system. Background Technology

[0002] Visible Light Communication (VLC) is a communication method that uses light-emitting diodes (LEDs) as signal transmitting nodes, free space as the transmission medium, and photodiodes (PDs) as signal receiving devices. Indoor environments such as airports, train stations, and large shopping malls typically employ numerous light sources for illumination, providing natural support for the construction of visible light communication networks. Furthermore, the vast and readily available spectrum resources of visible light communication can effectively alleviate communication pressure in these indoor hotspot scenarios. Therefore, research on indoor visible light communication has received increasing attention.

[0003] In indoor visible light communication systems, the distribution of light signal intensity on the receiving surface is primarily determined by the position of the light source. Uneven light intensity distribution on the receiving surface can lead to significant differences in communication experience for users at different locations. Therefore, designing a reasonable light source layout to minimize signal intensity differences at different locations on the receiving surface is a critical technical problem that needs to be solved in indoor visible light communication systems.

[0004] Most existing solutions to the above problems employ global search optimization schemes. However, when the optimization area is large, the number of iterations required for optimization is considerable, limiting optimization efficiency. Furthermore, current optimization schemes use functions related to the light intensity of the receiving surface as the objective function. In large-area scenarios, the computational cost of calculating the light intensity of all sampled points on the receiving surface is substantial, further reducing optimization efficiency. Therefore, achieving both high optimization performance and improved efficiency is a pressing technical problem that needs to be solved.

[0005] The background description is provided for the purpose of understanding the relevant technologies in this field and is not intended as an admission of prior art. Summary of the Invention

[0006] Therefore, the present invention aims to provide a method for optimizing the layout of light sources in an indoor visible light communication system that can both ensure optimized performance and improve optimization efficiency.

[0007] This invention provides a method for optimizing the light source layout of an indoor visible light communication system, characterized by the following steps:

[0008] 1) Determine the area and optimization order of the sub-region based on the distance from the geometric center of the sub-region to the geometric center of the global region, and then divide the sub-region;

[0009] 2) Based on the sub-region division order, the influence of the light source in the post-optimized sub-region is equivalently mapped to the influence of the light source at the center of the global region on each sub-region, and different compensation factors are used to simulate the influence on different sub-regions;

[0010] 3) Optimize the position of single light source in sub-regions with the goal of achieving uniformity of distance parameter distribution, thereby further improving optimization efficiency.

[0011] Optionally, the greater the distance from the geometric center of the sub-region to the geometric center of the global region, the smaller the area of ​​the sub-region, and the higher the priority of the optimization order.

[0012] Optionally, when the distance from the geometric center of the sub-region to the geometric center of the global region is equal and the area is also equal, any one of the sub-regions is selected as a reference sub-region, and the optimization order of the sub-regions is determined according to the distance from the geometric center of the sub-region to the geometric center of the reference sub-region.

[0013] Optionally, the received optical power at different points on the receiving surface is a function of the square of the straight-line distance from the projection point of the light source on the receiving surface to each point on the receiving surface, and the function is monotonically decreasing.

[0014] Optionally, the single-source position optimization compensation factor for the i-th sub-region is: in The projection points of the geometric centers of all Ni unoptimized subregions onto the receiving surface. (j = i+1, i+2, ... N) to the center of the i-th sub-region The sum of squared distances, The projection point (x) of the geometric center of the global region onto the receiving surface. c y c z) to the center position of the i-th sub-region The square of the distance.

[0015] Optionally, the projection point (x) of the light source in the i-th sub-region on the receiving surface i y i The squared distance from (x, y, z) to the receiving point (x, y, z) within the subregion is: u i =(xx) i ) 2 +(yy i ) 2 .

[0016] Optionally, when i=1, the impact of the unoptimized sub-region on the current region is simulated using a compensation factor, and the square of the distance u between the receiving point (x, y, z) and the projection point of the light source on the receiving surface within the corrected sub-region is obtained. i =(xx) i ) 2 +(yy i ) 2 +Q i ((xx c ) 2 +(yy c ) 2 ), where Q i As a compensation factor, x c With y c These are the x and y coordinates of the projection of the geometric center of the global region onto the receiving surface, respectively.

[0017] Optionally, when 1 < i < N, the influence of the optimized sub-region light source on the current sub-region is considered, and the influence of the unoptimized sub-region on the current region is simulated using a compensation factor. The square of the distance between the receiving point (x, y, z) and the projection point of the light source on the receiving surface within the corrected sub-region is obtained as follows: Among them, Q i As a compensation factor, x k With y k Let x and y be the x and y coordinates of the light source position projected onto the receiving surface of the k-th (k = 1, 2, ..., i-1) optimized sub-region.

[0018] Optionally, when i = N, considering the influence of the optimized sub-region light source in the current sub-region, the square of the distance between the receiving point (x, y, z) and the light source in the corrected sub-region is obtained as follows: Where, x k With y k Let x and y be the x and y coordinates of the projection point of the light source on the receiving surface of the k-th (k = 1, 2, ..., N-1) optimized sub-region.

[0019] Optional, according to:

[0020]

[0021] std.(x i y i )∈C i

[0022] Obtain the coordinates (x, y) of the light source in the i-th sub-region. i y i ),in For u i The mean, S iLet C be the area of ​​the i-th sub-region. i Let be the range of the i-th sub-region.

[0023] Other optional features and technical effects of the embodiments of the present invention are partly described below and partly apparent from reading this document. Attached Figure Description

[0024] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The elements shown are not limited to the scale shown in the drawings, and the same or similar reference numerals in the drawings denote the same or similar elements, wherein:

[0025] Figure 1 A schematic diagram of an indoor visible light communication system model that can implement embodiments of the present invention is shown;

[0026] Figure 2 A schematic diagram of area division in indoor visible light communication, which can implement embodiments of the present invention, is shown;

[0027] Figure 3 A flowchart illustrating a method for improving the performance of an indoor visible light communication system that can be implemented according to embodiments of the present invention is shown.

[0028] Figures 4a-4d A schematic diagram showing a comparison of the performance improvement effects of an indoor visible light communication system that can implement embodiments of the present invention is illustrated. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. Here, the illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention.

[0030] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0031] In an embodiment of the present invention, a regional light source optimization scheme based on pre-bias compensation is provided, which divides the entire optimization area into multiple sub-regions and optimizes the position of a single light source in each sub-region to improve optimization efficiency.

[0032] To address the issue that regional optimization schemes cannot fully consider the mutual influence between sub-regions, the regional division scheme provided in this application minimizes the influence between regions. Furthermore, a pre-bias compensation method is used before optimizing a single region to simulate the impact of the optimized region after compensation.

[0033] To address the issue that obtaining the light intensity at each point on the receiving surface requires too much computation when using the light intensity distribution on the receiving surface as the optimization standard, this application embodiment uses the uniformity of the square distribution of the distance from the light source to the projection point on the receiving surface to each receiving point on the receiving surface to describe the uniformity of the received light power distribution when optimizing the position of a single light source in a sub-region, thereby further improving the optimization efficiency.

[0034] Figure 1 A schematic diagram of an indoor visible light communication system model that can implement embodiments of the present invention is shown. Figure 1 The indoor visible light communication system 10 shown includes a central controller 101 and a signal transmitter 102. Figure 1 In the illustrated embodiment, the indoor lighting LED can act as a signal generator 102, emitting light signals carrying useful information while providing illumination. The LED light radiation, approaching the Lambertian light emitter, satisfies the Lambertian radiation model. Figure 1 As shown, multiple indoor lighting LEDs acting as signal transmitters 102 can operate collaboratively, and these indoor lighting LEDs acting as signal transmitters are controlled by a central controller 101. Figure 1 In the optical communication scenario, the performance of the visible light communication system can be improved by changing the layout of the light source (102). However, if the global multi-light source layout is optimized, although the performance of the visible light communication system can be improved, there are many parameters that need to be optimized at the same time, and the optimization efficiency is very low. If the global multi-light source is optimized by region, the optimal layout scheme cannot be obtained because the mutual influence factors between local regions cannot be accurately taken into account.

[0035] Figure 2 This diagram illustrates a region division method for indoor visible light communication, which can be implemented according to embodiments of the present invention. In the prior art, the impact of unoptimized regions on optimized regions cannot be accurately predicted, and sub-regions closer to the center are more significantly affected by other sub-regions than those at the edges. For example... Figure 2 The regional division shown is based on the principle of minimizing the impact between sub-regions. Figure 2 In the illustrated region partitioning scheme, the distance from the geometric center of the sub-region to the geometric center of the global region is ( Figure 2 The distance l in a) is used to determine the sub-region area and optimization order.

[0036] Where, the larger the value of l, the smaller the area of ​​the corresponding sub-region, and the higher the priority of optimization. For sub-regions with equal values ​​of l, their areas are also equal. Any one of these sub-regions is selected as the reference sub-region, which has the highest optimization priority. The priority of other sub-regions is determined by the distance between their geometric centers and the geometric centers of the reference sub-region; the greater the distance, the higher the priority. For example... Figure 2 The diagram shown illustrates the region division under the criterion of minimizing influence between sub-regions, using a 5m × 5m area as an example. Figure 2 The geometric centers of subregions 1, 2, 3, and 4 shown have the largest distances to the geometric center a of the global region, and the distances from the geometric centers of subregions 1, 2, 3, and 4 to the geometric center a of the global region are equal. Figure 2 In the illustrated embodiment, sub-region 1 is selected as the reference sub-region. Of course, sub-region 2, sub-region 3, or sub-region 4 could also be selected as the reference sub-region; this is merely for illustrative purposes and no specific limitation is made. Figure 2 When subregion 1 is selected as the reference subregion, the distance between the geometric center of subregion 2 and the geometric center of subregion 1 is the largest, so it has the highest priority. Similarly, the distance between the geometric center of subregion 3 and the geometric center of subregion 1 is equal to the distance between the geometric center of subregion 4 and the geometric center of subregion 1. Therefore, subregion 3 or subregion 4 can be selected for optimization. Figure 2 The optimization process for other sub-regions is similar to that for sub-regions 1, 2, 3, and 4, and will not be repeated here.

[0037] Figure 2 The number in the code indicates the optimization order of that sub-region. From... Figure 2 It can be seen that the central sub-region has a larger area and is optimized later, while the edge sub-regions have a smaller area and are optimized earlier. This is because the edge sub-regions are less affected by other regions, so these regions are optimized first. At the same time, considering that the sub-regions optimized earlier are more affected by the light sources in the unoptimized regions than those optimized later, the area of ​​the first-optimized region is set not to be larger than the area of ​​the later-optimized region when dividing the sub-regions, so as to reduce the influence range of the light sources in the unoptimized regions. Figure 2 The illustrated embodiment divides the area into rectangles, but in practical applications, the shape of the divided area is not limited. For example, it can be a circle, hexagon, ellipse, or other geometric shapes.

[0038] Figure 3 A flowchart illustrating a method for improving the performance of an indoor visible light communication system, which can be implemented according to embodiments of the present invention, is shown. Figure 3 The method for improving the performance of a visible light communication system, as shown, includes the following steps:

[0039] S301: Determine the sub-region area and optimization order based on the distance from the geometric center of the sub-region to the geometric center of the global region, and then perform sub-region division; this step uses... Figure 2 The region division method shown in the embodiment will not be described in detail here;

[0040] S302: Based on the order of sub-region division, the influence of the light source in the post-optimized sub-region is equivalently mapped to the influence of the light source at the center of the global region on each sub-region, and different compensation factors are used to simulate the influence on different sub-regions.

[0041] As shown in the above embodiment, the light source in the j-th sub-region will affect the light intensity distribution received on the receiving surface of the i-th (i < j)-th sub-region. However, since the optimization order of the j-th sub-region is later than that of the i-th (i < j)-th sub-region, the position of the light source in the j-th sub-region has not yet been determined when the i-th (i < j)-th sub-region is optimized, so its precise influence cannot be obtained. In order to improve the performance of the visible light communication system, it is necessary to reduce the error caused by this uncertain influence when optimizing the light source in the i-th sub-region. This scheme maps the influence of the light source in the later optimized sub-region to the influence of the light source at the center of the global region on each sub-region according to the sub-region division order, and uses different compensation factors to simulate the influence on different sub-regions. The specific scheme is as follows: When optimizing the i-th sub-region, it is assumed that there is a light source at the center of all the unoptimized Ni sub-regions, and the projection points of these light sources on the receiving surface To the center of the i-th sub-region Sum of squared distances for:

[0042]

[0043] Meanwhile, assuming there is a light source at the center of the global optimization region, its projection point (x) on the receiving surface... c y c z) to the center position of the i-th sub-region The square of the distance is:

[0044]

[0045] Therefore, the pre-compensation factor for the i-th sub-region can be obtained as:

[0046]

[0047] When optimizing the i-th sub-region, a pre-bias compensation factor Q is applied to the light source at the center position of the global region. i Adjustments were made to simulate the effects of other unoptimized Ni sub-region light sources.

[0048] S303: The goal of optimizing the light source position is to maximize the uniformity of the distance parameter distribution, and further optimize the layout of the light source. According to formula (1), the received light power P at different points on the receiving surface at a given height can be regarded as a function of the square value u of the straight-line distance from the projection point of the light source on the receiving surface to each point on the receiving surface, and this function is monotonically decreasing. Since the computational cost of u is less than that of P, the distribution of u can be used to approximate the distribution of P. Therefore, considering the improvement of optimization efficiency, when optimizing the position of a single light source in a sub-region, the goal of optimizing the light source position is to maximize the uniformity of the distance parameter distribution. The specific scheme is as follows.

[0049] The projection point (x) of the light source in the i-th sub-region on the receiving surface i y i The squared distance from (x, y, z) to the receiving point (x, y, z) within the subregion is:

[0050] u i =(xx) i ) 2 +(yy i ) 2 (4)

[0051] When i = 1, only the influence of the last Ni unoptimized regions on the current optimized region needs to be considered. A compensation factor can be used to adjust u. i Make corrections

[0052] u i =(xx) i ) 2 +(yy i ) 2 +Q i ((xx c ) 2 +(yy c ) 2 (5)

[0053] Q i As a compensation factor, x c With y c These are the x and y coordinates of the projection of the geometric center of the global region onto the receiving surface, respectively.

[0054] When 1 < i < N, it is necessary to consider not only the influence of the unoptimized regions after Ni on the current optimized region, but also the influence of the first i-1 optimized regions on the current region. Assume the projection point of the light source on the receiving surface of the k-th (k = 1, 2, ..., i-1) optimized sub-region is (x... k y k ,z), at this time u i It can be corrected to

[0055]

[0056] Among them, Q i As a compensation factor, x k With y k Let x and y be the x and y coordinates of the light source position projected onto the receiving surface of the k-th (k = 1, 2, ..., i-1) optimized sub-region.

[0057] When i = N, we only need to consider the influence of the first N-1 optimized regions on the current optimized region. At this time, u i It can be corrected to

[0058]

[0059] Where, x k With y k Let x and y be the x and y coordinates of the light source position projected onto the receiving surface of the k-th (k = 1, 2, ..., N-1) optimized sub-region.

[0060] Optimize the u of each point on the receiving surface of the sub-region i The fluctuation can be expressed as variance D i To measure this, the variance calculation formula is:

[0061]

[0062] Where S i Let C be the area of ​​the i-th sub-region. i Let i be the range of the i-th sub-region. For u i The mean is calculated by the following formula.

[0063]

[0064] Choose to make D i The smallest value (x) i y i Using the coordinates of the light source as the coordinates of the light source minimizes the fluctuation of the light power on the receiving surface. When optimizing the position of a single light source in the i-th sub-region, the optimization objective is to minimize the variance of the distance projected onto each point on the receiving surface. Thus, the light source position optimization problem is transformed into an optimization problem:

[0065]

[0066] This is a non-convex problem, and a closed-form solution cannot be obtained. However, commonly used optimization algorithms in existing light source optimization schemes, such as genetic algorithms and bat algorithms, can be used to find a solution.

[0067] Figures 4a-4d A schematic diagram comparing the performance improvement effects of an indoor visible light communication system that can implement embodiments of the present invention is shown; wherein... Figure 4aThis is a schematic diagram of the optical power distribution without implementing a light source distribution optimization scheme; Figure 4b The optical power distribution map is shown after optimizing the light source distribution using the Image Contrast Based Algorithm (ICBA). Figure 4c This is a diagram showing the optical power distribution after optimizing the light source distribution using two-dimensional distance parameters as the objective function. Figure 4d The optical power distribution diagram after optimizing the light source distribution using the method described in the embodiments of this application is shown in Table (1). Figures 4a-4d The numerical comparison of the methods, as shown in Table (1), reveals that, with room parameters and optical parameters remaining unchanged, the light source layout optimization method described in this application significantly reduces power fluctuation compared to the existing ICBA algorithm. Furthermore, when using the mean square error of the received power at each point on the receiving surface as a reference, the light source layout optimization method described in this application improves the uniformity of optical power by approximately 84% compared to the unoptimized scheme, and by approximately 68% compared to the ICBA algorithm. Simultaneously, the light source layout optimization method described in this application, with the uniformity of distance parameter distribution as the optimization objective, shows a performance decrease of only 0.1% compared to the scheme with the uniformity of optical power distribution as the objective function. It can be considered that the performance loss after simplifying the objective function is almost negligible. The algorithm running time under the simplified objective function is reduced by approximately 88% compared to the algorithm running time with received optical power as the objective function. This improves the overall optimization efficiency. This further verifies that the light source layout optimization method described in this application can improve the performance of the visible common communication system while reducing computational complexity.

[0068] Unless explicitly stated otherwise, the actions or steps of the methods and procedures described in the embodiments of the present invention do not necessarily have to be performed in a specific order and can still achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0069] This document describes several embodiments of the present invention; however, for the sake of brevity, the descriptions of the embodiments are not exhaustive, and identical or similar features or parts between the embodiments may be omitted. In this document, "one embodiment," "some embodiments," "example," "specific example," or "some examples" refers to embodiments applicable to at least one, but not all, of the present invention. The above terms do not necessarily refer to the same embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of the different embodiments or examples.

[0070] Table 1

[0071]

[0072] The exemplary systems and methods of the present invention have been specifically shown and described with reference to the above embodiments, which are merely examples of the best mode for implementing the systems and methods. Those skilled in the art will understand that various changes can be made to the embodiments of the systems and methods described herein without departing from the spirit and scope of the invention as defined in the appended claims when implementing the systems and / or methods.

Claims

1. A method for optimizing light source layout for indoor visible light communication system, characterized in that, Includes the following steps: 1) Determine the area and optimization order of the sub-region based on the distance from the geometric center of the sub-region to the geometric center of the global region, and then divide the sub-region; 2) Based on the sub-region division order, the influence of the light source in the post-optimized sub-region is equivalently mapped to the influence of the light source at the center of the global region on each sub-region, and different compensation factors are used to simulate the influence on different sub-regions; 3) Optimize the position of single light source in sub-regions with the goal of achieving uniformity in the distribution of distance parameters, thereby further improving optimization efficiency; wherein the first sub-region single light source position optimization compensation factor is: , is the distance squared from the projection point of the geometric center of all unoptimized N-i sub-regions on the receiving surface to the center position of the i th sub-region , is the distance squared from the projection point of the geometric center of all unoptimized N-i sub-regions on the receiving surface to the center position of the i th sub-region , is the distance squared from the projection point of the geometric center of all unoptimized N-i sub-regions on the receiving surface to the center position of the i th sub-region No. The projection point of the light source in each sub-region on the receiving surface To the receiving point within the sub-region The square of the distance is .

2. The method for optimizing the light source layout of an indoor visible light communication system according to claim 1, characterized in that, The greater the distance from the geometric center of the sub-region to the geometric center of the global region, the smaller the area of ​​the sub-region, and the higher the priority of the optimization order.

3. The method for optimizing the light source layout of an indoor visible light communication system according to claim 1, characterized in that, When the distance from the geometric center of the sub-region to the geometric center of the global region is equal and the area is also equal, any one of the sub-regions is selected as a reference sub-region, and the optimization order of the sub-regions is determined according to the distance from the geometric center of the sub-region to the geometric center of the reference sub-region.

4. The method for optimizing the light source layout of an indoor visible light communication system according to claim 1, characterized in that, The received optical power at different points on the receiving surface is a function of the square of the straight-line distance from the projection point of the light source on the receiving surface to each point on the receiving surface, and the function is monotonically decreasing.

5. The method for optimizing the light source layout of an indoor visible light communication system according to claim 1, characterized in that, when At that time, the compensation factor is used to simulate the impact of the unoptimized sub-region on the current region, and the receiving points within the corrected sub-region are obtained. The square of the distance from the projection point of the light source onto the receiving surface is: ,in As a compensation factor, , These are the x and y coordinates of the projection of the geometric center of the global region onto the receiving surface, respectively.

6. The method for optimizing the light source layout of an indoor visible light communication system according to claim 1, characterized in that, when hour, in, As a compensation factor, and For the first The horizontal and vertical coordinates of the light source position of each optimized sub-region projected onto the receiving surface.

7. The method for optimizing the light source layout of an indoor visible light communication system according to claim 1, characterized in that, when When considering the influence of the optimized sub-region on the current sub-region, the receiving points within the corrected sub-region are obtained. The square of the distance from the light source to the projection point on the receiving surface is ， in, and For the first The horizontal and vertical coordinates of the light source position of each optimized sub-region projected onto the receiving surface.

8. The method for optimizing the light source layout of an indoor visible light communication system according to any one of claims 1-7, characterized in that, according to: Obtain the i Coordinates of light sources in each sub-region , in for The mean, For the first i The area of ​​each sub-region For the first i The area range of each sub-region.

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