A visible light positioning-assisted multi-user optical communication system and method

Abstract

The present invention discloses a multi-user optical communication system and method assisted by visible light positioning, wherein the communication system comprises a micro base station and a user receiver; the micro base station comprises a mounting plate, a visible light locator is provided in the middle of the bottom surface of the mounting plate, and a plurality of automatic tracking optical communication devices are provided around the visible light locator on the bottom surface of the mounting plate; the visible light locator is connected to a plurality of automatic tracking optical communication devices via a serial bus; the visible light locator cyclically broadcasts the micro base station ID and the current working status data of the automatic tracking optical communication device to the coverage area; the user receiver sends its own 3D position coordinates and user identity to the visible light locator; the visible light locator specifies the automatic tracking optical communication device closest to the user and idle to establish a communication link with the user receiver. The present invention can effectively solve the bottleneck problem of poor quality and high bit error rate of radiation communication in point-to-surface or three-dimensional space of optical communication.

Description

Technical Field

[0001] The present invention belongs to the technical field of visible light communications, and in particular relates to a visible light positioning-assisted multi-user optical communication system and method. Background Art

[0002] Visible Light Communication (VLC) is considered by the industry to be an alternative technology to Wireless Personal Area Network (WPAN) communication technology due to its advantages such as no spectrum authorization, high security and confidentiality, ultra-wide spectrum of 400-800 THz and no electromagnetic radiation. It is expected to be widely used in the next generation of 6G, 7G and even 8G communication scenarios. At present, the transmitting devices of VLC mainly use light-emitting diodes (LED), laser diodes (LD) and the newly developed super-luminescent diodes (SLD), and the receiving devices usually use photodiodes (PIN), avalanche diodes (APD) and image sensors.

[0003] Usually, LED adopts spontaneous radiation mode, the light emitted is incoherent light, the spectrum is wide, the emission direction is omnidirectional, and the total output power can be high. However, due to the large emission angle, the optical power density is low. LD adopts amplified stimulated radiation mode, the light emitted is coherent light, the spectrum is narrow, the emission direction is highly directional, the output power can be high, and the optical power density is high. At present, the main structure of the experimentally verified VLC system is still point-to-point communication. If LED is used, a focusing lens needs to be installed at the front end of the LED to form a parallel light beam, and a convex lens needs to be installed at the receiving end to make the light converge on the surface of the photodetector (PD). The advantage of doing this is that the optical power density of the LED is effectively improved, which greatly improves the signal-to-noise ratio of the receiver, thereby greatly reducing the bit error rate of communication, thereby improving the communication quality.

[0004] However, this point-to-point VLC system will face some bottleneck problems if applied in the actual WPAN scenario. Usually, in the WPAN scenario, a micro base station will serve multiple users at the same time, so it is required to achieve omnidirectional radiation communication from point to surface or even point to three-dimensional space, just like WiFi. If the VLC micro base station uses LED, although it can also achieve point-to-surface coverage, the LED radiation power density is low, resulting in weak signals received by PD and low signal-to-noise ratio, which affects the communication quality. At this time, in order to improve the communication quality, we can only increase the radiation light power of the LED, but this will directly lead to excessive energy consumption of the base station, and the lighting will be too bright, resulting in poor user experience. If the VLC micro base station uses LD, due to its strong directionality, we can use milliwatt-level LD to implement point-to-point communication, which can effectively save energy consumption. But the problem is that how to establish a real-time point-to-point communication link with users at random locations on the ground is a bottleneck problem.

[0005] For example, a Chinese patent with publication number CN113162688A discloses a visible light bidirectional communication and positioning system, including a first communication node and a second communication node, wherein the first communication node includes a positioning light source, a first communication light source, a PIN / APD detector module, and a first driving device assembly that drives the first communication light source and the PIN / APD detector module to rotate; the second communication node includes a composite receiver, a second communication light source, and a second driving device that drives the second communication light source to rotate; the composite receiver is used to receive signals from the positioning light source and the first communication light source, and the composite receiver includes multiple detectors; the PIN / APD detector module is used to receive signals from the second communication light source. The system can realize simultaneous upload and download of data by two communication nodes in the visible light band through two communication nodes, and can realize positioning and tracking functions, so that the two communication nodes can maintain the alignment of the first communication light source and the composite receiver, and the second communication light source and the PIN / APD detector module even if relative motion occurs, thereby ensuring the communication quality. This patent can locate and track the location information of the nodes in real time, realize real-time alignment of the two communication nodes, and ensure the reliability and stability of visible light communication.

[0006] However, although this patent can realize point-to-point communication and positioning and tracking functions, the principle of its positioning is quite different from that of the present application. Summary of the invention

[0007] The purpose of the present invention is to provide a multi-user optical communication system and method assisted by visible light positioning to address the point-to-point communication link connection problem between a VLC micro base station and multiple users at random positions in the prior art. The system can provide broadband transmission services to multiple users at the same time with little mutual interference and has good application value.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A multi-user optical communication system assisted by visible light positioning comprises a VLC micro base station and a user receiver; the VLC micro base station comprises a mounting plate, a visible light locator is provided in the middle of the bottom surface of the mounting plate, and a plurality of automatic tracking optical communication devices are provided on the bottom surface of the mounting plate around the visible light locator; the visible light locator is connected to the plurality of automatic tracking optical communication devices via a serial bus, thereby realizing two-way communication between master and slave devices, wherein the visible light locator is the master device and the automatic tracking optical communication device is the slave device; the visible light locator cyclically broadcasts the VLC micro base station ID and the current working status data of the automatic tracking optical communication device to the coverage area; the user receiver sends its own 3D position coordinates and user identity to the visible light locator; the visible light locator specifies the automatic tracking optical communication device closest to the user and idle to establish a communication link with the user receiver according to the user's 3D position coordinates and identity.

[0010] Specifically, the visible light positioner includes a mounting seat, a heat sink and a positive N prism, N ≥ 3, and N∈Z + ; The regular N-shaped pyramid is installed on the mounting base through a heat sink, and the mounting base is installed in the middle of the bottom surface of the mounting plate; a control module, an LED drive modulation module and an infrared receiving module are arranged in the mounting base, and the LED drive modulation module and the infrared receiving module are respectively connected to the control module; a plurality of first infrared receiving tubes are arranged around the heat sink, and the first infrared receiving tubes are connected to the infrared receiving module; a circuit substrate is arranged on the N+1 faces of the regular N-shaped pyramid, and each of the circuit substrates is provided with an LED lamp, and the LED lamp is connected to the LED drive modulation module through the circuit substrate; the first infrared receiving tube is used to receive the 3D position coordinate information sent by the user; the LED drive modulation module is used to drive the LED lamps in different directions to emit frequency shift keying switch signals of different frequencies; the control module is used to process the received infrared signal and generate the LED drive signal.

[0011] Specifically, the automatic tracking optical communication device includes a base, on which a horizontal rotation servo mechanism, a pitch rotation servo mechanism and a beam projector connected in sequence are installed; a data processing unit, a driving unit and a communication signal processing unit are arranged in the base, and the driving unit and the communication signal processing unit are respectively connected to the data processing unit; the communication signal processing unit leads out an Ethernet port and an optical fiber port; the Ethernet port is connected to an indoor optical fiber modem, or the optical fiber port is connected to an indoor optical fiber; these two network ports are connected to a public network or a mobile communication network. A light emitting device and a second infrared receiving tube are arranged at the output end of the beam projector, and the light emitting device and the second infrared receiving tube are respectively connected to the data processing unit; the light emitting device is used for sending downlink broadband data, and the second infrared receiving tube is used for receiving uplink broadband data; the driving unit is used for driving the horizontal rotation servo mechanism and the pitch rotation servo mechanism to adjust the horizontal direction and pitch angle of the beam projector; the data processing unit is used for processing the data sent by the visible light locator, and generating a target tracking signal to the driving unit.

[0012] Specifically, the user receiver includes a signal processing module, a photodiode, an infrared transmitting tube and a ranging probe connected to the signal processing module; the photodiode is used to receive light signals emitted by a visible light locator and an automatic tracking optical communication device; the infrared transmitting tube is used to send infrared signals to the visible light locator and the automatic tracking optical communication device; the ranging probe is used to measure its own height data; the signal processing module is used to process and receive signals and generate modulated signals.

[0013] Corresponding to the above optical communication system, the present invention further proposes a multi-user optical communication method assisted by visible light positioning, comprising the following steps:

[0014] S1, the visible light locator cyclically broadcasts the VLC micro base station ID and the current working status identification data of the automatic tracking optical communication device towards its coverage area;

[0015] S2, after the user receiver receives the VLC micro base station ID and the current working state identification data of the automatic tracking optical communication device, it selects an unoccupied frequency resource as a carrier according to the current working state identification data, and uploads the user's 3D position coordinates and identity to the visible light locator;

[0016] S3, after receiving the 3D position coordinates and identity identifier, the visible light locator specifies the automatic tracking optical communication device closest to the user and idle to establish a communication link with the user receiver, and transmits the user's 3D position coordinates and identity identifier to the corresponding automatic tracking optical communication device through a serial bus;

[0017] S4, the automatic tracking optical communication device adjusts the horizontal direction and pitch angle of its own light beam projector according to the 3D position coordinates of the user, so that the light beam projector is aimed at the user receiver, and sends a channel estimation signal to the user receiver;

[0018] S5, after receiving the channel estimation signal, the user receiver evaluates whether the channel meets the broadband communication requirement. If so, broadband data transmission begins; if not, a recheck is performed.

[0019] Specifically, in step S3, the visible light locator first obtains the 3D position coordinates of all idle automatic tracking optical communication devices, and then selects the automatic tracking optical communication device closest to the user's 3D position coordinates; after establishing the communication link, it analyzes whether the communication link overlaps with other working communication links. If so, the adjacent automatic tracking optical communication device is selected to re-establish the communication link with the user receiver until the re-established communication link does not overlap with other working communication links.

[0020] Furthermore, if a suitable communication link cannot be found in an idle automatic tracking optical communication device, the working communication link can be migrated to an idle automatic tracking optical communication device that does not cause light beam overlap through analysis and scheduling, thereby freeing up space for communication links for new users and ensuring to the greatest extent possible that the communication links do not overlap.

[0021] Specifically, an inertial sensor is installed in the user receiver. If the user receiver shakes significantly and the shaking value exceeds a set threshold, the user receiver will re-estimate its own 3D position coordinates and upload the new 3D position coordinates to the visible light locator. The visible light locator then transmits the new 3D position coordinates to the automatic tracking optical communication device. The automatic tracking optical communication device corrects the horizontal direction and pitch angle of the light beam projector in real time according to the new 3D position coordinates, so that the projection direction of the light beam projector is always aligned with the user receiver.

[0022] Specifically, to obtain the user's 3D position coordinates, we must first define the following parameters:

[0023] Since the positions of N+1 LED lights in different directions are several millimeters apart and very close, it is approximately assumed that the 3D coordinate positions of the N+1 LED lights are the same, and the 3D coordinate vectors of the LED lights are uniformly defined as:

[0024] S=[x L ,y L ,z L ] T

[0025] The 3D unit normal vector of the i-th LED light is defined as:

[0026]

[0027] The 3D coordinate vector of the PD (photodetector) on the receiver user equipment (UE) is defined as:

[0028] U=[x U ,y U ,z U ] T

[0029] The unit normal vector of the PD (photodetector) is defined as: U

[0030] The 3D direction vector from the LED light position to the UE position is:

[0031] d=US=[x U -x L ,y U -y L ,z U -z L ] T

[0032] The distance between the LED light and the UE is: d = ||d||2

[0033] The radiation angle between the i-th LED and the UE is defined as φ i , then:

[0034]

[0035] The incident angle of UE relative to the i-th LED is defined as Then we have:

[0036]

[0037] The light intensity of the light signal from the i-th LED core reaching the UE through visible propagation can be expressed as:

[0038]

[0039] where β U is the response coefficient of PD, P L is the radiated light power of the LED, n is the Lambertian radiation lobe modulus (representing the directionality of the light source), m is the order of PD, A U is the receiving area of ​​PD, F i is the indicator function. When the function is The value is 1 when the condition is true, and 0 otherwise. represents the field of view of PD;

[0040] make Then we have:

[0041]

[0042] Divide the received light intensities from different LEDs by two to get the received intensity ratio α i,j , according to formula (2) it can be written as:

[0043]

[0044] Furthermore, let x D =x L -x U ,y D =y L -y U ,z D =z L -z U , U D =[x D ,y D ,z D ] can be regarded as the relative 3D coordinate of UE relative to the visible light locator, then formula (3) can be written as:

[0045]

[0046] Formula (4) can be further expressed as a homogeneous linear equation system AX = 0, where

[0047]

[0048]

[0049] According to the above definition, the present invention proposes a method for quickly estimating the 3D position coordinates of a user receiver, the steps are as follows:

[0050] The first step is to calculate the orthogonal matrix B = A T The eigenvalues ​​and eigenvectors of A, where B is a 3×3 matrix;

[0051] In the second step, the eigenvalues ​​are sorted from small to large to obtain the eigenvector corresponding to the minimum eigenvalue. The eigenvector is the optimal solution of the 3D normalized relative coordinates from the visible light locator to the UE, expressed as

[0052] In the third step, the receiver uses the ranging probe and inertial sensor to obtain the distance from the UE to the ceiling or floor, and further obtains the vertical distance h from the UE to the visible light locator. D ;

[0053] The fourth step is to use the formula Estimate the 3D coordinates U of UE, where [xL ,y L ,z L ] is the 3D coordinate of the visible light locator.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) the present invention connects a visible light locator with multiple automatic tracking optical communication devices through a serial bus, and matches the most suitable automatic tracking optical communication device for the user according to the user's actual 3D position coordinates, which can effectively solve the bottleneck problems of poor point-to-surface or three-dimensional radiation communication quality and high bit error rate in optical communication; (2) each automatic tracking optical communication device of the present invention still adopts point-to-point communication with the user equipment, which greatly saves the power consumption of the transmitting equipment; (3) the present invention adopts spatial light beam isolation between each communication link, and the information transmission interference between different users is small, which further improves the communication quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 Schematic diagram of the structure of a multi-user optical communication system assisted by visible light positioning in an embodiment of the present invention.

[0056] Figure 2 It is an inverted front view of the visible light locator in the embodiment of the present invention.

[0057] Figure 3 4 is a side view of a visible light locator in an embodiment of the present invention.

[0058] Figure 4 Schematic diagram of the structure of an automatic tracking optical communication device in an embodiment of the present invention.

[0059] Figure 5 It is a simplified plan view of a visible light locator in an embodiment of the present invention.

[0060] Figure 6 This is a configuration diagram of an application scenario of an optical communication system in an embodiment of the present invention.

[0061] Figure 7 It is a schematic diagram of three-dimensional distribution of positioning error performance simulation in an embodiment of the present invention.

[0062] In the figure: 100, mounting plate; 200, visible light locator; 201, mounting base; 202, heat sink; 203, regular tetrahedron; 204, control module; 205, LED drive modulation module; 206, infrared receiving module; 207, first infrared receiving tube; 208, circuit substrate; 209, LED lamp; 300, automatic tracking optical communication device; 301, base; 302, horizontal rotation servo mechanism; 303, pitch rotation servo mechanism; 304, beam projector; 305, data processing unit; 306, drive unit; 307, communication signal processing unit; 308, light emitting device; 309, second infrared receiving tube; 400, user receiver; 401, photodiode; 402, infrared transmitting tube; 403, ranging probe; 500, user terminal. DETAILED DESCRIPTION

[0063] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0064] like Figure 1 As shown, this embodiment provides a multi-user optical communication system assisted by visible light positioning, including a VLC micro base station and a user receiver 400; the VLC micro base station includes a mounting plate 100, a visible light locator 200 is provided in the middle of the bottom surface of the mounting plate 100, and 8 automatic tracking optical communication devices 300 are provided at equal intervals around the visible light locator 200 on the bottom surface of the mounting plate 100; the visible light locator 200 is connected to the 8 automatic tracking optical communication devices 300 through a serial bus, thereby realizing two-way communication between the master and slave devices, wherein the visible light locator 200 is connected to the 8 automatic tracking optical communication devices 300 through a serial bus, thereby realizing two-way communication between the master and slave devices, wherein the visible light locator 200 is connected to the 8 automatic tracking optical communication devices 300 through a serial bus, The optical locator 200 is the master device, and the automatic tracking optical communication device 300 is the slave device; the visible light locator 200 cyclically broadcasts the VLC micro base station ID and the current working status data of the automatic tracking optical communication device 300 to the coverage area; the user receiver 400 sends its own 3D position coordinates and user identity to the visible light locator 200; the visible light locator 200 specifies the automatic tracking optical communication device 300 closest to the user and idle to establish a communication link with the user receiver 400 based on the user's 3D position coordinates and identity.

[0065] Specifically, Figure 2 , 3As shown, the visible light locator 200 includes a mounting base 201, a heat sink 202 and a metal block of a square pyramid 203; the square pyramid 203 is mounted on the mounting base 201 through the heat sink 202, and the mounting base 201 is mounted in the middle of the bottom surface of the mounting plate 100; a control module 204, an LED drive modulation module 205 and an infrared receiving module 206 are arranged in the mounting base 201, and the LED drive modulation module 205 and the infrared receiving module 206 are respectively connected to the control module 204; four first infrared receiving tubes 207 are arranged around the heat sink 202, and the first infrared receiving tubes 207 are connected to the infrared receiving module 206; circuit substrates 208 (aluminum or copper) are arranged on the five faces of the square pyramid 203, and each of the circuit substrates 208 There is a standard Lambertian radiation LED lamp 209 on each of the five LED lamps 209, and the five LED lamps 209 are respectively welded on five circuit substrates 208; the LED lamp 209 is connected to the LED driving modulation module 205 through the circuit substrate 208; the height of the first infrared receiving tube 207 is slightly higher than the LED lamp 209, so as to prevent the signal emitted by the LED lamp 209 from affecting the infrared signal received by the first infrared receiving tube 207; the first infrared receiving tube 207 is used to receive the 3D position coordinate information sent by the user; the LED driving modulation module 205 is used to drive the LED lamps 209 in different directions to emit frequency shift keying switch signals of different frequencies; the control module 204 is used to process the received infrared signal, generate the LED driving signal, and perform serial bus communication between the master and slave devices.

[0066] Specifically, Figure 4As shown, the automatic tracking optical communication device 300 includes a base 301, on which a horizontal rotation servo mechanism 302, a pitch rotation servo mechanism 303 and a beam projector 304 connected in sequence are installed; a data processing unit 305, a driving unit 306 and a communication signal processing unit 307 are arranged in the base 301, and the driving unit 306 and the communication signal processing unit 307 are respectively connected to the data processing unit 305; the communication signal processing unit 307 leads to an Ethernet port and an optical fiber port; the output end of the beam projector 304 is provided with a light emitting device 308 (a narrow beam LED device is used in this embodiment) and a second The infrared receiving tube 309 (a broadband infrared receiving tube is used in this embodiment), the light emitting device 308 and the second infrared receiving tube 309 are respectively connected to the data processing unit 305; the light emitting device 308 is used to send downlink broadband data, and the second infrared receiving tube 309 is used to receive uplink broadband data; the driving unit 306 is used to drive the horizontal rotation servo mechanism 302 and the pitch rotation servo mechanism 303 to respectively perform 0-360° horizontal rotation and 0-90° vertical rotation to adjust the horizontal direction and pitch angle of the beam projector 304, so that the beam of the narrow beam LED device can always be aimed at the user receiver 400. The data processing unit 305 is used to process the data sent by the visible light locator 200 and generate a target tracking signal to the driving unit 306.

[0067] In this embodiment, the beam projector 304 may also use a micro-vibration mirror or an optical phased array (OPA) based on a micro-electromechanical system (MEMS) in a laser radar to adjust the beam angle, thereby realizing a real-time alignment function of the communication link.

[0068] Specifically, the user receiver 400 includes a signal processing module, a photodiode 401 (a high-speed photodiode is used in this embodiment) connected to the signal processing module, an infrared transmitting tube 402 and a ranging probe 403; the photodiode 401 is used to receive optical signals emitted by the visible light locator 200 and the automatic tracking optical communication device 300; the infrared transmitting tube 402 is used to send infrared signals to the visible light locator 200 and the automatic tracking optical communication device 300; the ranging probe 403 is used to measure the vertical distance between the user terminal (the user receiver 400 of this embodiment is connected to the user terminal 500 through a data interface) and the ceiling or the ground. If the user terminal 500 is tilted, the tilt angle can be measured by the inertial sensor in the user terminal 500, and then the vertical distance can be corrected; the signal processing module is used to process and receive signals and generate modulated signals.

[0069] This embodiment also provides a visible light positioning-assisted multi-user optical communication method, comprising the following steps:

[0070] S1, the visible light locator 200 cyclically broadcasts the VLC micro base station ID and the current working status identification data of the automatic tracking optical communication device 300 towards its coverage area; the current working status identification data of the automatic tracking optical communication device 300 is represented by several bytes of bit data; in this embodiment, a byte of 8 bits "10010110" is used to represent the current working status of 8 automatic tracking optical communication devices 300, the first bit "0" indicates that the first automatic tracking optical communication device 300 is currently in an idle state; the second bit "1" indicates that the second automatic tracking optical communication device 300 is currently in an occupied state, that is, it indicates the frequency resource occupancy identifier between the automatic tracking optical communication device 300 and the UE.

[0071] S2, after receiving the VLC micro base station ID and the current working state identification data of the automatic tracking optical communication device 300, the user receiver 400 selects an unoccupied frequency resource as a carrier according to the current working state identification data, and uploads the user's 3D position coordinates and identity (User Identification, UID) to the visible light locator 200;

[0072] S3, after receiving the 3D position coordinates and identity identifier, the visible light locator 200 specifies the automatic tracking optical communication device 300 closest to the user and idle to establish a communication link with the user receiver 400, and transmits the user's 3D position coordinates and identity identifier to the corresponding automatic tracking optical communication device 300 through the serial bus;

[0073] S4, after receiving the 3D position coordinates of the user, the automatic tracking optical communication device 300 converts them into a pitch angle and a rotation angle through analysis and calculation, and then sends them to the corresponding automatic tracking optical communication device 300, controls the horizontal rotation servo mechanism 302 and the pitch rotation servo mechanism 303 to adjust the horizontal direction and pitch angle of the beam projector 304, so that the beam projector 304 is aligned with the user receiver 400, and sends a channel estimation signal to the user receiver 400;

[0074] S5, after receiving the channel estimation signal, the user receiver 400 evaluates whether the channel meets the broadband communication requirement. If so, broadband data transmission begins; if not, a recheck is performed.

[0075] Specifically, in step S3, the visible light locator 200 first obtains the 3D position coordinates of all idle automatic tracking optical communication devices 300, and then selects the automatic tracking optical communication device 300 closest to the user's 3D position coordinates; after establishing the communication link, it analyzes whether the communication link overlaps with other working communication links. If so, the adjacent automatic tracking optical communication device 300 is selected to re-establish the communication link with the user receiver 400 until the re-established communication link does not overlap with other working communication links.

[0076] Specifically, an inertial sensor is installed in the user receiver 400. If the user receiver 400 shakes significantly and the shaking value exceeds a set threshold, the user receiver 400 will re-estimate its own 3D position coordinates and upload the new 3D position coordinates to the visible light locator 200. The visible light locator 200 will then transmit the new 3D position coordinates to the automatic tracking optical communication device 300. The automatic tracking optical communication device 300 will correct the horizontal direction and pitch angle of the light beam projector 304 in real time according to the new 3D position coordinates, so that the projection direction of the light beam projector 304 is always aligned with the user receiver 400.

[0077] Specifically, Figure 5 As shown, in order to obtain the user's 3D position coordinates, the following parameters must first be defined:

[0078] Since the positions of the five LED lights in different directions are several millimeters apart and very close, it is approximately assumed that the 3D coordinate positions of the five LED lights are the same, and the 3D coordinate vectors of the LED lights are uniformly defined as:

[0079] S=[x L ,y L ,z L ] T

[0080] The 3D unit normal vector of the i-th LED light is defined as:

[0081]

[0082] The 3D coordinate vector of the PD (photodetector) on the receiver user equipment (UE) is defined as:

[0083] U=[x U ,y U ,z U ] T

[0084] The unit normal vector of the PD (photodetector) is defined as: U

[0085] The 3D direction vector from the LED light position to the UE position is:

[0086] d=US=[x U -x L ,y U -y L ,z U -z L ] T

[0087] The distance between the LED light and the UE is: d = ||d||2

[0088] The radiation angle between the i-th LED and the UE is defined as φ i , then:

[0089]

[0090] The incident angle of UE relative to the i-th LED is defined as Then we have:

[0091]

[0092] The light intensity of the light signal from the i-th LED core reaching the UE through visible propagation can be expressed as:

[0093]

[0094] where β U is the response coefficient of PD, P L is the radiated light power of the LED, n is the Lambertian radiation lobe modulus (representing the directionality of the light source), m is the order of PD, A U is the receiving area of ​​PD, F i is the indicator function. When the function is The value is 1 when the condition is true, and 0 otherwise. represents the field of view of PD;

[0095] make Then we have:

[0096]

[0097] Divide the received light intensities from different LEDs by two to get the received intensity ratio α i,j , according to formula (2) it can be written as:

[0098]

[0099] Furthermore, let x D =x L -x U ,y D=y L -y U ,z D =z L -z U , U D =[x D ,y D ,z D ] can be regarded as the relative 3D coordinate of UE relative to the visible light locator, then formula (3) can be written as:

[0100]

[0101] Formula (4) can be further expressed as a homogeneous linear equation system AX = 0, where

[0102]

[0103]

[0104] According to the above definition, the present invention proposes a method for quickly estimating the 3D position coordinates of a user receiver, the steps are as follows:

[0105] The first step is to calculate the orthogonal matrix B = A T The eigenvalues ​​and eigenvectors of A, where B is a 3×3 matrix;

[0106] In the second step, the eigenvalues ​​are sorted from small to large to obtain the eigenvector corresponding to the minimum eigenvalue. The eigenvector is the optimal solution of the 3D normalized relative coordinates from the visible light locator to the UE, expressed as

[0107] In the third step, the receiver uses the ranging probe and inertial sensor to obtain the distance from the UE to the ceiling or floor, and further obtains the vertical distance h from the UE to the visible light locator. D ;

[0108] The fourth step is to use the formula Estimate the 3D coordinates U of UE, where [x L ,y L ,z L ] is the 3D coordinate of the visible light locator.

[0109] This embodiment uses the parameter settings in Table 1 below as an example to analyze and simulate the three-dimensional coordinate position method based on the regular tetrahedral visible light locator proposed in this embodiment. It should be pointed out that the method for quickly estimating three-dimensional coordinates proposed in the present invention is also applicable to visible light locators based on other regular N-prisms.

[0110] Table 1 Simulation parameters

[0111] parameter value <![CDATA[Room size (length * width * height) [l R , w R , h R > 10m×10m×5m Number of visible light locator wicks, N 5 <![CDATA[LED optical power, P L > 3W <![CDATA[LED half-power angle, θ 1 / 2 > 60 degrees LED Lambertian radiation lobe modulus, n 1 <![CDATA[PD receiving area, A U > <![CDATA[1cm 2 ]]> <![CDATA[PD photoelectric conversion efficiency, β U > 0.4A / W LED orientation angle,θ 20 degrees <![CDATA[Visible light locator coordinates, [x L , y L , z L > [0,0,4] <![CDATA[UE user receiver noise power, σ 2 > <![CDATA[10 -15 A 2 ]]> <![CDATA[A / D sampling frequency, f s > 96kHz Window points, L 9600 <![CDATA[Height of the UE from the ground, h U > 1.2m

[0112] The five LED lights of the visible light locator send frequency shift keying switch signals of different frequencies through a transistor or field effect tube switch control circuit. The frequency configuration of the five LED lights is shown in Table 2 below.

[0113] Table 2 LED light frequency configuration

[0114] LED serial number Frequency (Hz) LED0 1600 LED1 1800 LED2 2000 LED3 2200 LED4 2400

[0115] The A / D sampling frequency of the user receiver is set to 96kHz, the sampling window points are set to 9600, and the user receiver uses the Goertzel algorithm to extract the light intensity spectrum amplitude emitted by the five LED lamps. In this embodiment, the orientation normal vectors of the five LED lamps are: n0 = [0, 0, -1], n1 = [sinθ, 0, -cosθ], n2 = [0, sinθ, -cosθ], n3 = [-sinθ, 0, -cosθ] and n4 = [0, -sinθ, -cosθ]. The VLC micro base station is installed on the middle ceiling of a room with a length, width and height of 10m×10m×5m. Figure 6 As shown, the height of the user holding the UE from the floor is set to 1.2 m, and this height can be obtained by the distance detector in the UE.

[0116] Figure 7 The three-dimensional distribution diagram of the positioning error (LE) performance simulation of this embodiment is shown in FIG. Figure 7 It can be observed from (a) and (b) that when the PD of the UE terminal is placed flat, that is, when α = 0°, no matter how the UE azimuth angle β changes, the average positioning error (Location Error, LE) of the positioning algorithm in this embodiment is about 3.66 cm, and the maximum LE is about 12.7 cm. Figure 7 It can be observed in (c) and (d) that when the PD of the UE terminal is tilted upward by 20 degrees, that is, when α = 20°, no matter how the UE azimuth angle β changes, the average positioning error (Location Error, LE) of the positioning algorithm proposed by the system is about 3.75 cm, and the maximum LE is about 16.6 cm. Compared with the square of the PD, the positioning performance of the 20-degree tilt is slightly reduced, but the change is not significant. Figure 7It can be observed in (e)(f) that when the PD of the UE terminal is tilted upward by 40 degrees, that is, when α=40°, the LE of the UE in most areas is within 5 cm, while in some edge areas, its LE deteriorates rapidly and the positioning error is extremely large. The reason for this phenomenon is that when the UE is tilted too much, it will not receive the light signal emitted by one or two LEDs at certain azimuths and positions, resulting in the inability to extract the spectrum amplitude normally, the spectrum amplitude is distorted or extremely weak, and ultimately leads to a very large LE. To solve this problem, we can further consider eliminating these abnormal spectrum amplitudes so that they do not participate in the positioning algorithm processing. Furthermore, from Figure 7 It can be observed in (g) and (h) that when the PD of the UE terminal is tilted downward by 30 degrees, the average LE obtained is about 3.94 cm. In some edge areas, the LE error is larger, but does not exceed 60 cm.

[0117] Figure 7 The simulation results show that the proposed visible light positioning structure and algorithm can support small-angle tilt and random adjustment of azimuth angle of UE terminal. When the tilt angle (polarization angle) β∈[-20°, 20°], the average positioning error is about 4 cm, which can effectively meet the functional requirements of the proposed system. When the tilt angle of UE is too large, there is still a large area that can meet the functional requirements, and in some locations, further optimization can be used to alleviate the sharp deterioration of LE.

[0118] It should be understood by those skilled in the art that the embodiments of the present application can be provided as methods, systems or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0119] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0120] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0121] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0122] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A visible light positioning-assisted multi-user optical communication system, characterized in that: It comprises a micro base station and a user receiver; the micro base station comprises a mounting plate, a visible light locator is provided in the middle of the bottom surface of the mounting plate, and a plurality of automatic tracking optical communication devices are provided around the visible light locator on the bottom surface of the mounting plate; the visible light locator is connected to a plurality of automatic tracking optical communication devices via a serial bus; the visible light locator cyclically broadcasts the micro base station ID and the current working status data of the automatic tracking optical communication device to the coverage area; the user receiver sends its own 3D position coordinates and user identity to the visible light locator; the visible light locator specifies the automatic tracking optical communication device closest to the user and idle to establish a communication link with the user receiver according to the user's 3D position coordinates and identity; The visible light positioner comprises a mounting seat, a heat sink and a positive N prism, N≥3, and N∈Z + ; The regular N-shaped pyramid is mounted on a mounting base through a heat sink, and the mounting base is mounted on the middle of the bottom surface of the mounting plate; a control module, an LED drive modulation module and an infrared receiving module are arranged in the mounting base, and the LED drive modulation module and the infrared receiving module are respectively connected to the control module; a plurality of first infrared receiving tubes are arranged around the heat sink, and the first infrared receiving tubes are connected to the infrared receiving module; a circuit substrate is arranged on each of the N+1 faces of the regular N-shaped pyramid, and an LED lamp is arranged on each of the circuit substrates, and the LED lamp is connected to the LED drive modulation module through the circuit substrate; the first infrared receiving tube is used to receive 3D position coordinate information sent by the user; the LED drive modulation module is used to drive the LED lamp to emit frequency shift keying switch signals of different frequencies; the control module is used to process the received infrared signal and generate an LED drive signal.

2. The visible light positioning-assisted multi-user optical communication system according to claim 1, characterized in that: The automatic tracking optical communication device includes a base, on which a horizontal rotation servo mechanism, a pitch rotation servo mechanism and a light beam projector are installed, which are connected in sequence; a data processing unit, a driving unit and a communication signal processing unit are arranged in the base, and the driving unit and the communication signal processing unit are respectively connected to the data processing unit; a light emitting device and a second infrared receiving tube are arranged at the output end of the light beam projector, and the light emitting device and the second infrared receiving tube are respectively connected to the data processing unit; the light emitting device is used for sending downlink broadband data, and the second infrared receiving tube is used for receiving uplink broadband data; the driving unit is used for driving the horizontal rotation servo mechanism and the pitch rotation servo mechanism to adjust the horizontal direction and pitch angle of the light beam projector; the data processing unit is used for processing the data sent by the visible light locator, and generating a target tracking signal to the driving unit.

3. The visible light positioning-assisted multi-user optical communication system according to claim 1, characterized in that: The user receiver includes a signal processing module, a photodiode, an infrared transmitting tube and a ranging probe connected to the signal processing module; the photodiode is used to receive light signals emitted by a visible light locator and an automatic tracking optical communication device; the infrared transmitting tube is used to send infrared signals to the visible light locator and the automatic tracking optical communication device; the ranging probe is used to measure its own height data; the signal processing module is used to process and receive signals and generate modulated signals.

4. A method for rapidly estimating the 3D position coordinates of a user receiver, based on the visible light positioning-assisted multi-user optical communication system of claim 1, characterized in that: The following steps are involved: The first step is to calculate the orthogonal matrix B = A T A; among which: α i,j It represents the ratio of the light intensity from the i-th LED to the j-th LED, that is, Among them I i and I j represents the light intensity of the i-th LED lamp and the j-th LED lamp; and They represent the unit normal vectors of the i-th LED lamp along the x-axis, the y-axis and the z-axis respectively, and n represents the Lambertian radiation lobe modulus of the LED lamp; the orthogonal matrix B is a 3×3 matrix; The second step is to calculate the eigenvalues ​​and eigenvectors of the orthogonal matrix B; The third step is to sort the eigenvalues ​​in ascending order and obtain the eigenvector corresponding to the minimum eigenvalue. The eigenvector represents the optimal solution of the 3D normalized relative coordinates from the visible light locator to the user receiver, which is expressed as In the fourth step, the user receiver uses the ranging probe and inertial sensor to obtain the distance from itself to the ceiling or floor, and further obtains the vertical distance h from the user receiver to the visible light locator. D ; The fifth step is to use the formula Estimate the three-dimensional coordinates U of the user receiver, where [x L ,y L ,z L ] is the 3D coordinate of the visible light locator.

5. A visible light positioning assisted multi-user optical communication method, based on the visible light positioning assisted multi-user optical communication system according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, the visible light locator cyclically broadcasts the micro base station ID and the current working status identification data of the automatic tracking optical communication device towards its coverage area; S2, after receiving the micro base station ID and the current working state identification data of the automatic tracking optical communication device, the user receiver selects an unoccupied frequency resource as a carrier according to the current working state identification data, and uploads the user's 3D position coordinates and identity to the visible light locator; S3, after receiving the 3D position coordinates and identity identifier, the visible light locator specifies the automatic tracking optical communication device closest to the user and idle to establish a communication link with the user receiver, and transmits the user's 3D position coordinates and identity identifier to the corresponding automatic tracking optical communication device through a serial bus; S4, the automatic tracking optical communication device adjusts the horizontal direction and pitch angle of its own light beam projector according to the 3D position coordinates of the user, so that the light beam projector is aimed at the user receiver, and sends a channel estimation signal to the user receiver; S5, after receiving the channel estimation signal, the user receiver evaluates whether the channel meets the broadband communication requirement. If so, broadband data transmission begins; if not, a recheck is performed.

6. The visible light positioning-assisted multi-user optical communication method according to claim 5, characterized in that: In step S3, the visible light locator first obtains the 3D position coordinates of all idle automatic tracking optical communication devices, and then selects the automatic tracking optical communication device closest to the user's 3D position coordinates; after establishing the communication link, it analyzes whether the communication link overlaps with other working communication links. If so, the adjacent automatic tracking optical communication device is selected to re-establish the communication link with the user receiver until the re-established communication link does not overlap with other working communication links; if a suitable communication link cannot be found in the idle automatic tracking optical communication devices, the working communication link can be migrated to an idle automatic tracking optical communication device that does not cause light beam overlap through analysis and scheduling, so as to make room for the communication link for the newly connected user, thereby maximizing the guarantee that the communication links do not overlap.

7. The visible light positioning-assisted multi-user optical communication method according to claim 5, characterized in that: The user receiver is installed with an inertial sensor. If the user receiver shakes significantly and the shaking value exceeds the set threshold, the user receiver will re-estimate its own 3D position coordinates and upload the new 3D position coordinates to the visible light locator. The visible light locator then transmits the new 3D position coordinates to the automatic tracking optical communication device. The automatic tracking optical communication device corrects the horizontal direction and pitch angle of the light beam projector in real time according to the new 3D position coordinates, so that the projection direction of the light beam projector is always aligned with the user receiver.

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