Optical camera near field communication method and system based on lamp strip space division multiplexing

Abstract

The application discloses an optical camera near field communication method and system based on lamp strip space division multiplexing, and belongs to the technical field of visible light communication. The method comprises the following steps: using a lamp strip array composed of multiple lamp strips as a transmitting end, using a signal with a specific frequency to drive the lamp strip and control the exposure time of an optical camera to shoot a template image with uniform gray scale. The center line of each lamp strip is extracted by a barycenter method to determine a data extraction position. Serial binary data is modulated into a PAM8 signal, and space division multiplexing is realized by corresponding lamp strip emission. Meanwhile, a video is shot by using an optical camera to receive signals, and images are extracted frame by frame and preprocessed. According to the data extraction position, corresponding gray scale values are extracted. Finally, the extracted gray scale values are normalized, resampled, synchronized, converted from parallel to serial, equalized and demodulated to recover original data. The method significantly improves the data rate of the optical camera communication system and meets the demand of optical camera near field communication.

Description

Technical Field

[0001] This invention belongs to the field of visible light communication technology, specifically relating to a near-field communication method for optical cameras based on light strip spatial multiplexing. Background Technology

[0002] Visible light communication (VLC) systems, with their advantages of no spectrum licensing required, low power consumption, and high security, have become an effective solution for wireless communication in specific scenarios. While broadband photodetectors can achieve high-speed VLC, their complexity, high cost, and sensitivity to light direction make finding more suitable receiving devices urgent. Currently, most mainstream mobile terminals incorporate optical cameras as imaging devices, employing CMOS image sensors with rolling shutters. Using optical cameras for optical camera communication can overcome the problems of complex equipment, high cost, and sensitivity to light direction, showing broad application potential. However, in the process of receiving high-frequency flickering light signals and pixelating visible light signals using the rolling shutter line-by-line exposure principle, the communication rate still falls short of the demands for high-speed wireless transmission. The pixel exposure process can be viewed as a moving average filter, which limits the bandwidth of the optical camera communication system. Therefore, as the communication rate increases, the distortion of the received signal becomes more severe, causing the bit error rate to exceed the system's tolerable threshold. Furthermore, although cameras can easily receive signals from multiple light sources, the non-uniformity of light emission leads to uneven grayscale distribution in the image. When the brightness exceeds a certain range, causing the charge generated by the photosensitive material to exceed the pixel's capacity, highlight overflow occurs, resulting in bright stripes covering dark stripes, increasing the bit error rate, and preventing normal communication. Currently, most optical camera communication systems use LED point light sources as transmitters. However, the non-uniformity of light emission from LED point light sources as Lambertian light sources makes it difficult to determine the data extraction location and increases the bit error rate. Furthermore, when multiple LED point light sources transmit signals simultaneously, severe crosstalk problems occur, making them unsuitable as transmitters for SDM (Space Division Multiplexing).

[0003] Existing technology provides a visible light communication method based on LEDs and a mobile phone camera. In a visible light communication system, the transmitting end encodes the data to be transmitted into a binary data stream, which is then represented by an LED dot matrix. After successfully reading the information represented by the LED dot matrix, the receiving end decodes each data frame to obtain the original data to be transmitted. However, using LED point light sources as the transmitting end can lead to difficulties in determining the data extraction location due to their uneven emission, increasing the bit error rate. When multiple LED point light sources transmit signals simultaneously, severe crosstalk problems can occur, thereby reducing the data rate of the optical camera communication system. Summary of the Invention

[0004] To overcome the shortcomings of uneven LED point light emission, crosstalk between multiple light sources, and low communication rate in the existing OCC system, this invention provides a near-field communication method and system for optical cameras based on LED strip spatial multiplexing.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] This invention provides a near-field communication method for optical cameras based on LED strip spatial division multiplexing, the method comprising:

[0007] S1: Set N light strips as light sources, drive the light strips and take pictures of the light sources as template images;

[0008] S2: Extract the center line of each light strip in the template image as the reference position for data extraction;

[0009] S3: Modulate the raw data to be sent to obtain a modulated signal; divide the modulated signal into N parallel driving signals to drive N light strips respectively;

[0010] S4: Capture the video of the driven LED strip, extract the LED strip image frame by frame; and preprocess all LED strip images to obtain the preprocessed LED strip image;

[0011] S5: Extract grayscale values ​​from all preprocessed light strip images based on the data extraction reference position;

[0012] S6: Recover the original data based on the extracted grayscale values.

[0013] Preferably, in step S1, N light strips are placed in N light slots as light sources, and the N light slots are arranged in parallel.

[0014] Preferably, after driving the light strip with a DC signal, an optical camera is used to photograph the light source to obtain a template image.

[0015] Preferably, all N light strips are COB-LED light strips.

[0016] Preferably, in step S2, the center line of each light strip in the template image is extracted using the centroid method as the reference position for data extraction; specifically, based on the grayscale distribution of the template image, the grayscale centroid point is calculated row by row, and the grayscale centroid point is used as the center point of the light strip in that row; all the center points are combined into a center line as the reference position for data extraction.

[0017] Preferably, in step S3, the specific method for dividing the modulation signal into N parallel driving signals to drive N light strips is as follows:

[0018] S3.1: Divide the modulation signal into N parallel modulation signals;

[0019] S3.2: For any modulated signal, divide it into several effective data segments of equal length;

[0020] S3.3: Add a pre-defined header before each valid data segment, and encapsulate the header and valid data segments into a data packet.

[0021] S3.4: Repeat the setting three times for each data packet and encapsulate all data packets sequentially to obtain the corresponding drive signal;

[0022] S3.5: Repeat steps S3.2-S3.4 for each modulation signal to obtain N driving signals, which drive N LED strips.

[0023] Preferably, the modulation signal is a PAM8 signal.

[0024] Preferably, in step S4, the preprocessing of all light strip images includes grayscale conversion and filtering for noise reduction.

[0025] Preferably, in step S6, the specific method for recovering the original data based on the extracted grayscale values ​​is as follows:

[0026] S6.1: Normalize the grayscale values ​​to obtain normalized grayscale values;

[0027] S6.2: Based on the line sampling rate of the optical camera, resample the normalized gray values ​​to obtain the resampled data;

[0028] S6.3: Perform symbol synchronization on the resampled data and locate the data header to determine the starting position of the data packet;

[0029] S6.4: Extract the valid data segments according to the start position of the data packet; concatenate all valid data segments in sequence to form serial data;

[0030] S6.5: Equalize and demodulate the serial data to recover the original data.

[0031] The present invention also provides an optical camera near-field communication system based on LED strip spatial multiplexing for implementing the above method, the system comprising:

[0032] The light source setting module is used to set N light strips as light sources, and after driving the light strips, the light source is captured as a template image.

[0033] The reference position determination module is used to extract the center line of each light strip in the template image as the reference position for data extraction;

[0034] The driving module is used to modulate the raw data to be transmitted to obtain a modulated signal; and to divide the modulated signal into N parallel driving signals to drive N light strips.

[0035] The LED strip image extraction module is used to capture LED strip video after driving, extract LED strip images frame by frame, and preprocess all LED strip images to obtain preprocessed LED strip images.

[0036] The grayscale extraction module extracts grayscale values ​​from all preprocessed light strip images based on the data extraction reference position.

[0037] The data recovery module recovers the original data based on the extracted grayscale values.

[0038] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0039] This invention employs COB-LED light strips as a line light source, which, compared to LED point light sources, offers more uniform illumination and less crosstalk. This reduces the bit error rate and improves data transmission accuracy. Furthermore, COB-LED light strips occupy less space, allowing for the use of more signal sources and achieving higher communication speeds and data throughput. Spatial division multiplexing technology further improves space utilization, allowing the simultaneous use of multiple signal sources and enhancing communication efficiency. The use of PAM8 signal transmission increases spectral efficiency, enabling the transmission of more data within the same bandwidth and achieving higher communication rates. Therefore, this invention offers high optical camera communication rates and has significant application value in the field of visible light communication technology. Attached Figure Description

[0040] Figure 1 This is a flowchart of the optical camera near-field communication method based on LED strip spatial multiplexing described in Example 1.

[0041] Figure 2 This is a flowchart of the optical camera near-field communication method based on LED strip spatial multiplexing described in Example 2.

[0042] Figure 3 This is a flowchart of the near-field communication method for optical cameras based on LED strip spatial multiplexing described in Example 2.

[0043] Figure 4 This is a schematic diagram of the optical camera near-field communication system based on LED strip spatial multiplexing as described in Example 3. Detailed Implementation

[0044] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent.

[0045] To better illustrate this embodiment, some parts in the accompanying drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions;

[0046] It will be understood by those skilled in the art that certain well-known structures and their descriptions may be omitted in the accompanying drawings.

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] Example 1

[0049] This embodiment provides a near-field communication method for optical cameras based on LED strip spatial multiplexing, such as... Figure 1 As shown, the method includes:

[0050] S1: Set N light strips as light sources, drive the light strips and take pictures of the light sources as template images;

[0051] S2: Extract the center line of each light strip in the template image as the reference position for data extraction;

[0052] S3: Modulate the raw data to be sent to obtain a modulated signal; divide the modulated signal into N parallel driving signals to drive N light strips respectively;

[0053] S4: Capture the video of the driven LED strip, extract the LED strip image frame by frame; and preprocess all LED strip images to obtain the preprocessed LED strip image;

[0054] S5: Extract grayscale values ​​from all preprocessed light strip images based on the data extraction reference position;

[0055] S6: Recover the original data based on the extracted grayscale values.

[0056] First, N light strips are set as light sources, and images of these light strips are captured after driving them to serve as template images. Next, the center line of each light strip in the template image is extracted as the reference position for data extraction. Then, the raw data to be transmitted is modulated to obtain a modulated signal. The modulated signal is divided into N parallel driving signals to drive the corresponding N light strips. Subsequently, the driven light strip video is captured frame by frame, and the image of each light strip is extracted. All light strip images are preprocessed to obtain preprocessed light strip images. Based on the data extraction reference position, grayscale values ​​are extracted from all preprocessed light strip images. Finally, based on the extracted grayscale values, the original data is recovered. Through this series of steps, efficient optical communication transmission and data recovery can be achieved.

[0057] Example 2

[0058] This embodiment provides a near-field communication method for optical cameras based on LED strip spatial multiplexing, such as... Figure 1 As shown, the method includes:

[0059] S1: Set N light strips as light sources, drive the light strips and take pictures of the light sources as template images;

[0060] S2: Extract the center line of each light strip in the template image as the reference position for data extraction;

[0061] S3: Modulate the raw data to be sent to obtain a modulated signal; divide the modulated signal into N parallel driving signals to drive N light strips respectively;

[0062] S4: Capture the video of the driven LED strip, extract the LED strip image frame by frame; and preprocess all LED strip images to obtain the preprocessed LED strip image;

[0063] S5: Extract grayscale values ​​from all preprocessed light strip images based on the data extraction reference position;

[0064] S6: Recover the original data based on the extracted grayscale values.

[0065] First, N light strips are set as light sources, and images of these light strips are captured after driving them to serve as template images. Next, the center line of each light strip in the template image is extracted as the reference position for data extraction. Then, the raw data to be transmitted is modulated to obtain a modulated signal. The modulated signal is divided into N parallel driving signals to drive the corresponding N light strips. Subsequently, the driven light strip video is captured frame by frame, and the image of each light strip is extracted. All light strip images are preprocessed to obtain preprocessed light strip images. Based on the data extraction reference position, grayscale values ​​are extracted from all preprocessed light strip images. Finally, based on the extracted grayscale values, the original data is recovered. Through this series of steps, efficient optical communication transmission and data recovery can be achieved.

[0066] In S1, such as Figure 2 As shown, N light strips are placed in N light slots as light sources, and the N light slots are arranged in parallel.

[0067] After driving the light strip with a DC signal, an optical camera is used to photograph the light source to obtain a template image.

[0068] All N light strips are COB-LED light strips.

[0069] In step S2, the center line of each light strip in the template image is extracted using the centroid method as the reference position for data extraction. Specifically, based on the grayscale distribution of the template image, the grayscale centroid point is calculated row by row, and the grayscale centroid point is used as the center point of the light strip in that row. All the center points are combined into a center line as the reference position for data extraction.

[0070] In S3, such as Figure 3 As shown, the specific method for dividing the modulation signal into N parallel driving signals to drive N light strips is as follows:

[0071] S3.1: Divide the modulation signal into N parallel modulation signals;

[0072] S3.2: For any modulated signal, divide it into several effective data segments of equal length;

[0073] S3.3: Add a pre-defined header before each valid data segment, and encapsulate the header and valid data segments into a data packet.

[0074] S3.4: Repeat the setting three times for each data packet and encapsulate all data packets sequentially to obtain the corresponding drive signal;

[0075] S3.5: Repeat steps S3.2-S3.4 for each modulation signal to obtain N driving signals, which drive N LED strips.

[0076] Preferably, the modulation signal is a PAM8 signal.

[0077] In step S4, the preprocessing performed on all light strip images includes grayscale conversion and filtering for noise reduction.

[0078] In S6, such as Figure 2 As shown, the specific method for recovering the original data based on the extracted grayscale values ​​is as follows:

[0079] S6.1: Normalize the grayscale values ​​to obtain normalized grayscale values;

[0080] S6.2: Based on the line sampling rate of the optical camera, resample the normalized gray values ​​to obtain the resampled data;

[0081] S6.3: Perform symbol synchronization on the resampled data and locate the data header to determine the starting position of the data packet;

[0082] S6.4: Extract the valid data segments according to the start position of the data packet; concatenate all valid data segments in sequence to form serial data;

[0083] S6.5: Equalize and demodulate the serial data to recover the original data.

[0084] Example 3

[0085] This embodiment provides an optical camera near-field communication system based on LED strip spatial multiplexing, used to implement the method described in Embodiment 1 or 2, such as... Figure 4 As shown, the system includes:

[0086] The light source setting module is used to set N light strips as light sources, and after driving the light strips, the light source is captured as a template image.

[0087] The reference position determination module is used to extract the center line of each light strip in the template image as the reference position for data extraction;

[0088] The driving module is used to modulate the raw data to be transmitted to obtain a modulated signal; and to divide the modulated signal into N parallel driving signals to drive N light strips.

[0089] The LED strip image extraction module is used to capture LED strip video after driving, extract LED strip images frame by frame, and preprocess all LED strip images to obtain preprocessed LED strip images.

[0090] The grayscale extraction module extracts grayscale values ​​from all preprocessed light strip images based on the data extraction reference position.

[0091] The data recovery module recovers the original data based on the extracted grayscale values.

[0092] The same or similar labels correspond to the same or similar parts;

[0093] The terms used to describe positional relationships in the accompanying drawings are for illustrative purposes only and should not be construed as limiting this patent.

[0094] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A near-field communication method for optical cameras based on LED strip spatial multiplexing, characterized in that, The method includes: S1: Set N light strips as light sources, drive the light strips and take pictures of the light sources as template images; S2: Extract the center line of each light strip in the template image as the reference position for data extraction; S3: Modulate the raw data to be sent to obtain a modulated signal; divide the modulated signal into N parallel driving signals to drive N light strips respectively; S4: Capture the video of the driven LED strip, extract the LED strip image frame by frame; and preprocess all LED strip images to obtain the preprocessed LED strip image; S5: Extract grayscale values ​​from all preprocessed light strip images based on the data extraction reference position; S6: Recover the original data based on the extracted grayscale values; All N light strips are COB-LED light strips; In step S2, the center line of each light strip in the template image is extracted using the centroid method and used as the reference position for data extraction. Specifically, based on the grayscale distribution of the template image, the grayscale centroid point is calculated row by row and used as the center point of the light strip in that row. All the center points are combined into a center line, which is used as the reference position for data extraction. In step S3, the specific method for dividing the modulation signal into N parallel driving signals to drive N light strips is as follows: S3.1: Divide the modulation signal into N parallel modulation signals; S3.2: For any modulated signal, divide it into several effective data segments of equal length; S3.3: Add a pre-defined header before each valid data segment, and encapsulate the header and valid data segments into a data packet. S3.4: Repeat the setting three times for each data packet and encapsulate all data packets sequentially to obtain the corresponding drive signal; S3.5: Repeat steps S3.2-S3.4 for each modulation signal to obtain N driving signals, which drive N LED strips.

2. The optical camera near-field communication method based on LED strip spatial multiplexing according to claim 1, characterized in that, In step S1, N light strips are placed in N light slots as light sources, and the N light slots are arranged in parallel.

3. The optical camera near-field communication method based on LED strip spatial multiplexing according to claim 1, characterized in that, After driving the light strip with a DC signal, an optical camera is used to photograph the light source to obtain a template image.

4. The optical camera near-field communication method based on LED strip spatial multiplexing according to claim 1, characterized in that, The modulation signal is a PAM8 signal.

5. The optical camera near-field communication method based on LED strip spatial multiplexing according to claim 1, characterized in that, In step S4, the preprocessing performed on all light strip images includes grayscale conversion and filtering for noise reduction.

6. The optical camera near-field communication method based on LED strip spatial multiplexing according to claim 5, characterized in that, In step S6, the specific method for recovering the original data based on the extracted grayscale values ​​is as follows: S6.1: Normalize the grayscale values ​​to obtain normalized grayscale values; S6.2: Based on the line sampling rate of the optical camera, resample the normalized gray values ​​to obtain the resampled data; S6.3: Perform symbol synchronization on the resampled data and locate the data header to determine the starting position of the data packet; S6.4: Extract the valid data segments according to the start position of the data packet; concatenate all valid data segments in sequence to form serial data; S6.5: Equalize and demodulate the serial data to recover the original data.

7. A near-field communication system for an optical camera based on LED strip spatial multiplexing, used to implement the method described in any one of claims 1-6, characterized in that, The system includes: The light source setting module is used to set N light strips as light sources, and after driving the light strips, the light source is captured as a template image. The reference position determination module is used to extract the center line of each light strip in the template image as the reference position for data extraction; The driving module is used to modulate the raw data to be transmitted to obtain a modulated signal; and to divide the modulated signal into N parallel driving signals to drive N light strips. The LED strip image extraction module is used to capture LED strip video after driving, extract LED strip images frame by frame, and preprocess all LED strip images to obtain preprocessed LED strip images. The grayscale extraction module is used to extract grayscale values ​​from all preprocessed light strip images based on the data extraction reference position. The data recovery module is used to recover the original data based on the extracted grayscale values.

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