A CSK constellation control method and device for a CSK system

Abstract

A CSK constellation control method and device for a CSK system, the device comprising a CSK system transmitting device and a CSK system receiving device, wherein the CSK constellation control method comprises six steps: UE feedback device type, AP generates and synchronizes constellation map lookup table, AP sends downlink probe signal, UE feedback SNR and incident angle, AP looks up and sends codebook index number, and AP transmits modulated data. The application is aimed at a CSK system with changing channel state, and considers the filter passband frequency shift characteristic when the light incident angle changes, so as to ensure the communication performance of the system.

Description

Technical Field

[0001] This invention relates to the field of wireless optical communication, and more particularly to a CSK constellation control method and apparatus for CSK systems. Background Technology

[0002] Visible light communication is a technology that uses LEDs to transmit signals and photodetectors to receive them, thus providing both illumination and communication functions simultaneously. Due to its advantages such as resistance to electromagnetic interference, abundant spectrum resources, and low construction costs, it has attracted widespread attention from researchers. Within visible light communication, there is a technique called Color Shift Keying (CSK), which uses multi-color LEDs for communication. In a CSK system, the transmitter uses multiple monochromatic lights as primary colors, and by changing the proportions of each color in the multi-color LEDs, different modulated signals are transmitted.

[0003] Correspondingly, the receiver of a CSK system typically requires multiple filters with different wavelengths to separate multicolor signals. A key issue is that the passband of the filter changes with the angle of incidence. That is, under non-perpendicular incidence, the passband of the filter shifts towards shorter wavelengths. In this article, the wireless access point is referred to as an AP.

[0004] Due to the aforementioned characteristics of optical filters, when the user equipment (UE) moves, not only does the transmission distance change, but the angle of incidence also alters, both of which affect the channel state. However, existing CSK systems mostly use fixed constellation diagrams, leading to performance degradation when channel states change. Furthermore, existing constellation interaction modes often only consider changes in the signal-to-noise ratio (SNR), neglecting the impact of the angle of incidence on the filter's passband, resulting in a deviation from real-world scenarios. Therefore, there is an urgent need for a constellation interaction method and apparatus for CSK systems that can interactively control the CSK constellation diagram when channel states change, thereby improving the overall communication performance of the system. Summary of the Invention

[0005] In view of this, the main objective of the present invention is to provide a CSK constellation control method and apparatus for CSK systems, in order to partially solve at least one of the above-mentioned technical problems.

[0006] To achieve the above objectives, as one aspect of the present invention, a CSK constellation control method for a CSK system is provided, specifically including the following steps:

[0007] Step 1: The UE provides feedback on device information; the device information includes device type and filter passband information; among which, the device type is divided into: randomly moving user, fixed incident angle user, and incident angle limited user; the filter passband information includes passband width and center wavelength λ0;

[0008] Step two, the AP generates and synchronizes the constellation lookup table; the AP receives the filter passband information and, according to the formula... The center wavelength λ(ψ) of the filter is calculated for different incident angles ψ, where n represents the refractive index of air. Then, the AP considers different signal-to-noise ratios (SNR) and incident angle ranges ψ, and performs CSK constellation diagram optimization design. The optimization objective is to minimize the bit error rate of the CSK system, and the variable is the CSK constellation diagram. After obtaining the CSK constellation diagrams for different incident angles ψ and SNR ranges, the AP establishes a global constellation diagram lookup table, constellation diagram lookup sub-table I, or constellation diagram lookup word table II corresponding to the device type and sends it to the UE. The table includes modulation order, incident angle range ψ, SNR range, and index number information.

[0009] For randomly moving users, the AP considers a large range of signal-to-noise ratio (SNR) and incident angle (ψ) and establishes a global constellation lookup table; the established global constellation lookup table is shown in Table 1.

[0010] Table 1 Global Constellation Chart Lookup Table

[0011] 1 <![CDATA[SNR0-SNR1]]> 4 0-10° constellation Figure 1 2 <![CDATA[SNR0-SNR1]]> 4 10°-20° constellation Figure 2 …… …… …… …… …… 9 <![CDATA[SNR0-SNR1]]> 4 80°-90° Constellation Chart 9 10 <![CDATA[SNR1-SNR2]]> 8 0-10° Constellation Chart 10 11 <![CDATA[SNR1-SNR2]]> 8 10°-20° Constellation Chart 11 …… …… …… …… ……

[0012] Optionally, for users with a fixed incident angle (such as laptops and industrial fixed equipment), the AP only needs to consider a large signal-to-noise ratio (SNR) range and establish a constellation diagram lookup sub-table I. The established constellation diagram lookup sub-table I is shown in Table 2.

[0013] Table 2. Zodiac Chart Lookup Subtable I

[0014]

[0015]

[0016] Optionally, for users with limited incident angles (such as mobile robots whose receivers are fixed and not adjustable), the AP only needs to consider a small range of incident angles ψ (e.g., 0-20°) and establish a constellation lookup sub-table II. The established constellation lookup sub-table II is shown in Table 3.

[0017] Table 3. Zodiac Chart Lookup Subtable II

[0018] 1 <![CDATA[SNR0-SNR1]]> 4 0-10° constellation Figure 1 2 <![CDATA[SNR0-SNR1]]> 4 10°-20° constellation Figure 2 3 <![CDATA[SNR1-SNR2]]> 8 0-10° constellation Figure 3 4 <![CDATA[SNR1-SNR2]]> 8 10°-20° constellation Figure 4 …… …… …… …… ……

[0019] Step 3: The AP sends a downlink probe signal; the probe signal is a signal known to both the AP and the UE, and is used for channel estimation.

[0020] Step four: The UE feeds back the signal-to-noise ratio (SNR) and incident angle (ψ) via uplink signals. Specifically, upon receiving the probe signal, the UE obtains the SNR and incident angle (ψ) at that moment through channel estimation and sends them to the AP.

[0021] For randomly moving users and users with limited incident angle, the signal-to-noise ratio (SNR) and incident angle (ψ) must be fed back after each change in channel state.

[0022] For users with a fixed incident angle, the incident angle ψ value is only fed back the first time, and then only the signal-to-noise ratio (SNR) is fed back each time the channel state changes.

[0023] Step 5: The AP searches for and sends the CSK constellation map index number. After receiving the signal-to-noise ratio (SNR) and the incident angle (ψ), the AP, in conjunction with the preset modulation order, finds the CSK constellation map index number in the corresponding global constellation map lookup table, constellation map lookup table I, or constellation map lookup table II, and sends the index value to the UE.

[0024] Step 6: The AP modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to the UE. The UE demodulates the data according to the CSK constellation diagram corresponding to the index number.

[0025] As a second aspect of the present invention, a CSK system transmitting device is provided, comprising: a calculation unit, a search unit, a feedback unit, a modulation unit, and a transmission unit;

[0026] The calculation unit is used to solve the optimization problem, generate the CSK constellation diagram, and establish a lookup table; the lookup unit is used to retrieve the corresponding CSK constellation diagram index number from the lookup table based on information such as modulation order, signal-to-noise ratio (SNR), and incident angle (ψ); the feedback unit is used to provide feedback on the CSK constellation diagram index number information; the modulation unit is used to modulate the transmitted data based on the corresponding CSK constellation diagram in the lookup table; and the transmission unit is used to transmit the data to be transmitted via multi-color LEDs.

[0027] As a third aspect of the present invention, a CSK system receiving device is provided, comprising: a synchronization unit, an estimation unit, a search unit, a receiving unit, and a demodulation unit;

[0028] The system includes: a synchronization unit for synchronizing and storing the constellation lookup table sent by the AP; an estimation unit for performing channel estimation based on the received probe signal to obtain the signal-to-noise ratio (SNR) and incident angle (ψ) information; a lookup unit for retrieving the corresponding CSK constellation from the constellation lookup table based on the received CSK constellation index number; a receiving unit for receiving the signal transmitted by the multicolor LED through a filter and photodetector assembly; and a demodulation unit for demodulating the received data based on the found CSK constellation.

[0029] Based on the above technical solution, it can be seen that the CSK constellation control method and apparatus for CSK systems of the present invention have at least one or a portion of the following beneficial effects compared to the prior art:

[0030] The method proposed in this invention is designed for CSK systems. Taking into account the passband frequency shift characteristics of the filter when the light incident angle changes, it adjusts the CSK constellation diagram in scenarios where the channel changes, thereby ensuring the communication performance of the system. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a scenario where users are randomly moved in Embodiment 1 of the present invention;

[0032] Figure 2 This is a schematic block diagram of a CSK system transmitting device according to Embodiment 1 of the present invention;

[0033] Figure 3 This is a schematic block diagram of a CSK system receiving device according to Embodiment 1 of the present invention;

[0034] Figure 4 This is a flowchart of a constellation control method for a CSK system according to Embodiment 1 of the present invention;

[0035] Figure 5 This is a schematic diagram of a scenario with a fixed incident angle for a user in Embodiment 2 of the present invention;

[0036] Figure 6 This is a schematic diagram of a scenario for users with limited incident angle range in Embodiment 3 of the present invention;

[0037] Figure 7 This is a schematic diagram of a channel uplink / downlink reciprocity scenario in Embodiment 4 of the present invention;

[0038] Figure 8 This is a flowchart of the CSK constellation control method in the uplink-downlink reciprocal scenario of Embodiment 4 of the present invention. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0040] The purpose of this invention is to provide a CSK constellation control method and apparatus for CSK systems, in order to solve the problem that the existing technology uses a fixed CSK constellation diagram and does not consider the influence of the light incident angle on the filter passband, which leads to a deterioration in the system communication performance.

[0041] Example 1: Randomly moving users

[0042] In this embodiment, we consider Visible Light Communication (VLC) with only a downlink channel, i.e., a VLC system link (where only the AP sends data to the UE, and the UE does not send data to the AP). The UE device type is a random mobile user, and the scenario is as follows. Figure 1 As shown. Figure 2 and Figure 3 A schematic diagram of the CSK transmitting and receiving devices is given. In this scenario, the AP acts as the CSK transmitting device and the UE acts as the CSK receiving device. Figure 4 A schematic diagram of the constellation control process applicable to this scenario is provided, which includes the following steps:

[0043] Step 1: The UE provides feedback on device information; the specific feedback content includes the device type being a random mobile user and filter passband information, which includes the passband width and center wavelength λ0.

[0044] Step two, the AP generates and synchronizes the global constellation lookup table; the AP receives the filter passband information and, according to the formula... The center wavelength λ(ψ) of the filter is calculated for different incident angles ψ, where n represents the refractive index of air. Then, the AP considers different signal-to-noise ratios (SNR) and incident angle ranges ψ, and performs CSK constellation diagram optimization design for each. The optimization objective is to minimize the bit error rate of the CSK system, with the CSK constellation diagram as the variable. After obtaining the CSK constellation diagrams for different incident angles ψ and SNR ranges, the AP establishes a global constellation diagram lookup table and sends it to the UE; the table includes modulation order, incident angle range ψ, SNR range, and index number information.

[0045] Step 3: The AP sends a downlink probe signal, which is a signal known to both the AP and the UE, and is used for channel estimation.

[0046] Step four: The UE feeds back the signal-to-noise ratio (SNR) and incident angle (ψ) via uplink signals. Specifically, upon receiving the probe signal, the UE obtains the current SNR and incident angle (ψ) through channel estimation and sends them to the AP. Furthermore, the UE feeds back the SNR and incident angle (ψ) values ​​each time the channel state changes.

[0047] Step 5: The AP searches for and sends the CSK constellation map index number. After receiving the signal-to-noise ratio (SNR) and incident angle (ψ) value, the AP, in conjunction with the preset modulation order, finds the CSK constellation map index number in the global constellation map lookup table and sends the index value to the UE.

[0048] Step 6: The AP modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to the UE. The UE demodulates the data according to the CSK constellation diagram corresponding to the index number.

[0049] For randomly moving users, the AP considers a large range of signal-to-noise ratio (SNR) and incident angle (ψ) and establishes a global CSK constellation lookup table. The established global constellation lookup table is shown in Table 1.

[0050] Table 1 Global Constellation Chart Lookup Table

[0051] 1 <![CDATA[SNR0-SNR1]]> 4 0-10° constellation Figure 1 2 <![CDATA[SNR0-SNR1]]> 4 10°-20° constellation Figure 2 …… …… …… …… …… 9 <![CDATA[SNR0-SNR1]]> 4 80°-90° Constellation Chart 9 10 <![CDATA[SNR1-SNR2]]> 8 0-10° Constellation Chart 10 11 <![CDATA[SNR1-SNR2]]> 8 10°-20° Constellation Chart 11 …… …… …… …… ……

[0052] Example 2: Fixed angle of incidence for users

[0053] In this embodiment, we consider a fixed incident angle at the UE, but a time-varying channel in a multi-color VLC system, such as turbulent channels caused by microscopic particles in industrial scenarios, or changing illumination intensity at the AP. The UE device type is a user with a fixed incident angle, and the scenario is as follows: Figure 5 As shown. The interaction flow is as follows:

[0054] Step 1: The UE provides feedback on device information; the specific feedback content includes the device type being a user with a fixed incident angle and filter passband information, which includes the passband width and center wavelength λ0.

[0055] Step two, the AP generates and synchronizes the constellation lookup table; the AP receives the filter passband information and the given incident angle ψ, and then uses the formula... The center wavelength λ(ψ) of the filter at the incident angle ψ is calculated, where n represents the refractive index of air. Then, based on the given incident angle ψ, the AP optimizes the CSK constellation diagram for different signal-to-noise ratio (SNR) ranges. The optimization objective is to minimize the bit error rate of the CSK system, with the CSK constellation diagram as the variable. After obtaining the CSK constellation diagrams for different SNR ranges, the AP establishes a constellation diagram lookup sub-table I and sends it to the UE; the table includes modulation order, SNR range, and index number information.

[0056] Step 3: The AP sends a downlink probe signal; the probe signal is a signal known to both the AP and the UE, and is used for channel estimation.

[0057] Step four: The UE feeds back the signal-to-noise ratio (SNR) and the incident angle (ψ) via uplink signals. Specifically, the UE only sends the incident angle (ψ) value during the first feedback; thereafter, it only feeds back the SNR value after each channel state change.

[0058] Step 5: The AP searches for and sends the CSK constellation map index number. After receiving the signal-to-noise ratio (SNR) value, the AP, in conjunction with the preset modulation order, finds the CSK constellation map index number in the constellation map lookup sub-table I and sends the index value to the UE.

[0059] Step 6: The AP modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to the UE; the UE demodulates the data according to the CSK constellation diagram corresponding to the index number.

[0060] For users with a fixed incident angle (such as laptops and industrial fixed equipment), the AP only needs to consider a large signal-to-noise ratio (SNR) range and establish a CSK constellation lookup sub-table I. The established constellation lookup sub-table I is shown in Table 2.

[0061] Table 2. Zodiac Chart Lookup Subtable I

[0062] 1 <![CDATA[SNR0-SNR1]]> 4 constellation Figure 1 2 <![CDATA[SNR1-SNR2]]> 8 constellation Figure 2 3 <![CDATA[SNR2-SNR3]]> 16 constellation Figure 3

[0063] Example 3: Users with limited incident angle

[0064] In this embodiment, considering the limited incident angle range of the UE, such as a horizontally moving robot, the incident angle variation range is related to the AP coverage range. The UE device type is an incident angle-limited user, and the scenario is as follows: Figure 6 As shown. The interaction flow is as follows:

[0065] Step 1: The UE provides feedback on device information. The specific feedback content includes the device type being an angle-limited user and filter passband information, which includes the passband width and center wavelength λ0.

[0066] Step two, the AP generates and synchronizes the constellation lookup table; the AP receives the filter passband information and, according to the formula... The center wavelength λ(ψ) of the filter is calculated for different incident angles ψ, where n represents the refractive index of air. Then, the AP considers different signal-to-noise ratios (SNR) and a range of small incident angles ψ, and performs CSK constellation diagram optimization design for each. The optimization objective is to minimize the bit error rate of the CSK system, with the CSK constellation diagram as the variable. After obtaining the CSK constellation diagrams for different incident angles ψ and SNR ranges, the AP establishes a constellation diagram lookup sub-table II and sends it to the UE; the table includes modulation order, incident angle ψ range, SNR range, and index number information.

[0067] Step 3: The AP sends a downlink probe signal; the probe signal is a signal known to both the AP and the UE, and is used for channel estimation.

[0068] Step four: The UE feeds back the signal-to-noise ratio (SNR) and incident angle (ψ) via uplink signals. Specifically, upon receiving the probe signal, the UE obtains the current SNR and incident angle (ψ) through channel estimation and sends them to the AP. Furthermore, the UE feeds back the SNR and incident angle (ψ) values ​​every time the channel state changes.

[0069] Step 5: The AP searches for and sends the CSK constellation map index number. After receiving the signal-to-noise ratio (SNR) and incident angle (ψ) value, the AP, in conjunction with the preset modulation order, finds the CSK constellation map index number in the constellation map lookup sub-table II and sends the index value to the UE.

[0070] Step six: The AP modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to the UE. The UE demodulates the data according to the CSK constellation diagram corresponding to the index number.

[0071] For users with limited incident angles (such as mobile robots whose receivers are fixed and not adjustable), the AP only needs to consider a small range of incident angles ψ (e.g., 0-20°), and establish a constellation lookup sub-table II. The established constellation lookup sub-table II is shown in Table 3.

[0072] Table 3. Zodiac Chart Lookup Subtable II

[0073] 1 <![CDATA[SNR0-SNR1]]> 4 0-10° constellation Figure 1 2 <![CDATA[SNR0-SNR1]]> 4 10°-20° constellation Figure 2 3 <![CDATA[SNR1-SNR2]]> 8 0-10° constellation Figure 3 4 <![CDATA[SNR1-SNR2]]> 8 10°-20° constellation Figure 4 …… …… …… …… ……

[0074] Example 4: Uplink and Downlink Channel Reciprocity Scenario

[0075] In this embodiment, it is assumed that both uplink and downlink devices are multi-color VLC links and the channel is reciprocal, meaning that both devices have the same type, the same filter information, and the same signal-to-noise ratio (SNR) and incident angle (ψ). The scenario is as follows: Figure 7 As shown. In this case, only one party needs to perform channel estimation. The interaction process is as follows. Figure 8 As shown. The specific steps are as follows:

[0076] Step 1: Both parties provide equipment information; the equipment information includes equipment type and filter passband information. Equipment type is categorized as: randomly moving user, fixed incident angle user, and incident angle restricted user; filter passband information includes passband width and center wavelength λ0.

[0077] Step two, both parties confirm the reciprocal link;

[0078] Step 3: Device 1 generates and synchronizes the constellation lookup table; Device 1, based on the filter passband information, uses the formula... The center wavelength λ(ψ) of the filter at different incident angles ψ is calculated, where n represents the refractive index of air. Then, device 1 considers different signal-to-noise ratios (SNR) and incident angle ranges ψ, and performs CSK constellation diagram optimization design for each. The optimization objective is to minimize the bit error rate of the CSK system, with the CSK constellation diagram as the variable. After obtaining the CSK constellation diagrams for different incident angles ψ and SNR ranges, device 1 establishes a global constellation diagram lookup table, constellation diagram lookup word table I, or constellation diagram lookup word table II corresponding to the device type and sends it to device 2. The table includes the modulation order, the incident angle range ψ, the SNR range, and the index number information.

[0079] Step 4: Device 1 sends a downlink probe signal; the probe signal is a signal known to both devices and is used for channel estimation.

[0080] Step 5: Device 2 feeds back the signal-to-noise ratio (SNR) and incident angle (ψ) via uplink signals. Specifically, Device 2 receives the probe signal, obtains the SNR and incident angle (ψ) at that moment through channel estimation, and sends them to Device 1. Since uplink and downlink are reciprocal, Device 1 does not need to perform channel estimation again.

[0081] Optionally, for randomly moving users and users with limited incident angle, the signal-to-noise ratio (SNR) and incident angle (ψ) should be fed back after each change in channel state.

[0082] Optionally, for users with a fixed incident angle, the incident angle ψ value is only fed back the first time, and then only the signal-to-noise ratio (SNR) is fed back each time the channel state changes.

[0083] Step 6: Device 1 searches for and sends the CSK constellation map index number. After receiving the signal-to-noise ratio (SNR) and incident angle (ψ), Device 1, in conjunction with the pre-set modulation order, finds the CSK constellation map index number in the corresponding global constellation map lookup table, constellation map lookup word table I, or constellation map lookup word table II, and sends the index value to the UE.

[0084] Step 7: Device 1 modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to Device 2. Device 2 demodulates the data according to the CSK constellation diagram corresponding to the index number.

[0085] Step 8: Device 2 modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to Device 1. Device 1 demodulates the data according to the CSK constellation diagram corresponding to the index number.

[0086] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A CSK constellation control method for a CSK system, characterized in that, The method includes the following steps: Step 1: The UE provides device information. This information includes device type and filter passband information. Device type is categorized as: randomly moving user, fixed angle of incidence user, and angle-restricted user. Filter passband information includes passband width and center wavelength. ; Step two, the AP generates and synchronizes a constellation lookup table or a constellation lookup sub-table; the AP receives the filter passband information and, according to the formula... Calculate different incident angles The center wavelength of the filter at that time ,in The refractive index of air is then used, and the AP considers different signal-to-noise ratios (SNR) and incident angles. Within the range of [variable name], CSK constellation diagram optimization designs are performed separately. The optimization objective is to minimize the bit error rate of the CSK system, with the CSK constellation diagram as the variable, and different incident angles are obtained. After mapping the CSK constellation within the range and signal-to-noise ratio (SNR) range, the AP establishes a global constellation lookup table, constellation lookup sub-table I, or constellation lookup sub-table II corresponding to the device type and sends it to the UE; the table includes the modulation order and incident angle. Range, signal-to-noise ratio (SNR) range, and index number information; For randomly moving users, the AP considers a larger angle of incidence. Establish a global constellation lookup table based on the range and signal-to-noise ratio (SNR) range; For users with a fixed incident angle, the AP only needs to consider a large signal-to-noise ratio (SNR) range and establish a constellation diagram to look up sub-table I; For users with limited incident angles, the AP only needs to consider a small range of incident angles ψ and establish a constellation diagram to look up sub-table II; Step 3: The AP sends a downlink probe signal; the probe signal is a signal known to both the AP and the UE, and is used for channel estimation. Step four: The UE feeds back the signal-to-noise ratio (SNR) and incident angle via uplink signals. In this process, the UE receives the probe signal and obtains the signal-to-noise ratio (SNR) and incident angle at that moment through channel estimation. And report back to AP; For randomly moving users and users with limited incident angles, the signal-to-noise ratio (SNR) and incident angle must be fed back after each change in channel state. ; For users with a fixed angle of incidence, the angle of incidence is only provided on the first feedback. After that, only the signal-to-noise ratio (SNR) is fed back each time the channel state changes; Step 5: The AP searches for and sends the CSK constellation map index number. After receiving the signal-to-noise ratio (SNR) and incident angle (ψ), the AP, in conjunction with the preset modulation order, finds the CSK constellation map index number in the corresponding global constellation map lookup table, constellation map lookup sub-table I, or constellation map lookup sub-table II, and sends the index value to the UE. Step 6: The AP modulates the data according to the CSK constellation diagram corresponding to the index number and transmits the data to the UE. The UE demodulates the data according to the CSK constellation diagram corresponding to the index number.

2. A CSK system transmitting device, used to implement the method of claim 1, characterized in that, The device includes: a computing unit, a search unit, a feedback unit, a modulation unit, and a transmission unit; The computational unit is used to solve the optimization problem, generate the CSK constellation diagram, and establish a lookup table; the lookup unit is used to determine the modulation order, signal-to-noise ratio (SNR), and incident angle. The system retrieves the corresponding CSK constellation index number from the lookup table; the feedback unit provides the CSK constellation index number; the modulation unit modulates the transmitted data based on the corresponding CSK constellation in the lookup table; and the transmission unit transmits the data to be transmitted via multi-color LEDs.

3. A CSK system receiving device, used to implement the method of claim 1, characterized in that, The device includes: Synchronization unit, estimation unit, search unit, receiving unit, demodulation unit; The synchronization unit synchronizes and stores the constellation lookup table sent by the AP; the estimation unit performs channel estimation based on the received probe signal to obtain the signal-to-noise ratio (SNR) and the angle of incidence. Information; the lookup unit is used to retrieve the corresponding CSK constellation from the constellation lookup table based on the received CSK constellation index number value; the receiving unit is used to receive the signal transmitted by the multicolor LED through the filter and photodetector assembly; the demodulation unit is used to demodulate the received data based on the found CSK constellation.

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