A code-shifted optical jamming private communication system based on OCC

Abstract

The present invention relates to an OCC-based code-shifted light interference private communication system. The system adds an interference LED array to the information-release LED array of an information release center, with the two arranged alternately. The information release center encapsulates a control frame or information frame and constructs an interference frame associated therewith. The information release LED array and the interference LED array are synchronously driven by an amplification circuit, allowing mobile phone users to receive an interfered strip image. The mobile phone user demodulates and decodes the strip information using a code-shift indicator value negotiated with the information release center, obtaining information pushed to the mobile phone user by the information release center. A user can only demodulate and decode the strip information using the code-shifted light interference of their own code-shift indicator value. The present invention can utilize a broadcast visible light channel to encrypt the user information at the physical layer, thereby ensuring the privacy of the user information and expanding the targeted release and push functions of information.

Description

Technical Field

[0001] The present invention belongs to the technical field of visible light imaging communications and relates to an OCC-based code-shift light interference private communication system. Background Art

[0002] The Optical Camera Communication (OCC) system is a broadcasting system. The LEDs used in the information dissemination center flash at a frequency imperceptible to the human eye. Users within the LED light source's coverage area, using the rolling shutter exposure mode of a CMOS image sensor, receive alternating light and dark stripes. Information is then transmitted by demodulating and decoding these stripes. OCC not only shares the advantages of Visible Light Communication (VLC), such as abundant spectrum resources, energy conservation, and immunity to electromagnetic interference, but also offers the advantages of low network construction costs due to the high penetration of LEDs and mobile smart communication devices. Furthermore, OCC is easily accessible due to its ease of operation for ordinary mobile phone users. Therefore, OCC holds broad application prospects in areas such as information push, indoor positioning and navigation, broadcast notifications, and intelligent transportation.

[0003] In developed OCC systems and research both domestically and internationally, the transmitter broadcasts information. Users within the direct and reflected coverage of the LED light source receive the same information, meaning all users receive the same information. The transmitter uses the same modulation and demodulation mode for all users, ensuring that all users receive the same demodulated information. This makes it impossible to differentiate information reception for each user, and even more so, it makes it impossible to guarantee user information privacy. Currently, there is little research on private OCC communications, leaving a significant technical gap. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an OCC-based code-shifted optical interference private communication system, which can effectively ensure the privacy of each user's information when there are multiple users in the LED light source coverage area.

[0005] In order to solve the above technical problems, the OCC-based code shift light interference private communication system of the present invention includes an information release center and a mobile phone user. In the information release center, the main control module encodes the information to be released by the mobile phone user and encapsulates the control frame and the information frame. It is characterized in that the LED array is composed of the lamp beads of the information release LED array and the lamp beads of the interference LED array arranged alternately. The main control module uses the code shift indication value negotiated by the mobile phone user and the information release center to construct the interference frame associated with the control frame and the information frame respectively, and realizes the synchronization of the control frame and the interference frame associated therewith, and the information frame and the interference frame associated therewith. OOK modulation; wherein the load of the interference frame associated with the control frame is the code shift information of the control frame load, the load of the interference frame associated with the information frame is the code shift information of the information frame load, and the number of code shift bits is equal to the code shift indication value; the modulated control frame signal or information frame signal and the interference frame signal synchronously drive the information release LED array and the interference LED array to emit light respectively; the mobile phone user collects the original image formed by the LED array light and extracts the strip image, uses the code shift indication value to perform offset demodulation and decoding to remove light interference, obtains the information to be released by the user, and displays it on the mobile phone screen; the code shift indication value is a random integer in the range of 1-24.

[0006] The lamp beads in the information release LED array and the lamp beads in the interference LED array are arranged alternately in strips or in rings.

[0007] The control frame, information frame and interference frame have the same frame structure, which is composed of a frame header, a user sequence number, a packet sequence number, a payload and an end symbol arranged in sequence.

[0008] The frame header consists of 6 bits, which are "111110", and the end character is "0".

[0009] The payload of the control frame is a bit sequence of "#NN" after Manchester encoding, where NN is the code shift indicator value; the payload of the information frame is a bit sequence obtained by first encoding the information to be published in UTF-8, then converting it into binary data, and finally expanding it into Manchester encoding.

[0010] Assume that the code shift indication value is K. The code shift information of the control frame payload is composed of the control frame payload smoothly shifted by K bits, filling the first K bits, and discarding the last K bits. The code shift information of the information frame payload is composed of the information frame payload smoothly shifted by K bits, filling the first K bits, and discarding the last K bits.

[0011] When the code shift indicator value K is an even number, the first K bits are filled with 0101…01; when the code shift indicator value K is an odd number, the first K-1 bits are filled with 0101…01, and the Kth bit is filled with 0.

[0012] The method for the mobile phone user to obtain the information to be published by the user by performing staggered demodulation and decoding using the code shift indicator value is as follows:

[0013] Step 1: Preprocess the strip image to obtain a strip grayscale image. According to the set grayscale threshold, demodulate each single strip in the strip information corresponding to the payload into a code element value of 0, 1 or 2 to obtain a complete frame of payload data;

[0014] Step 2: Encode and group the payload data according to the code shift indicator value K. Each group contains K code elements, and the groups are grouped from the front to the back. The number of code elements in the last group is less than or equal to K.

[0015] Step 3: subtract the first group of data of the interference frame payload from the first group of data of the coded packet to obtain the first group of data of the information frame payload; use the first group of data of the information frame payload as the second group of data of the interference frame payload; subtract the second group of data of the interference frame payload from the second group of data of the coded packet to obtain the second group of data of the information frame payload; use the second group of data of the information frame payload as the third group of data of the interference frame payload, and subtract the third group of data of the interference frame payload from the third group of data of the coded packet to obtain the third group of data of the information frame payload; and so on, to obtain the Manchester coded data of the information frame payload;

[0016] Step 4: Manchester decode the Manchester-encoded data in the information frame payload, and then perform UTF-8 decoding on the Manchester-decoded data to obtain the data information transmitted in this frame;

[0017] Repeat steps 1 to 4 to decode and demodulate all the strip information with optical interference sent to the user by the information release center to obtain the information to be released by the user.

[0018] Beneficial effects:

[0019] The present invention adds an interference LED array to the information release LED array of the information release center, and the two are arranged alternately; the information release center encapsulates the control frame or information frame, and constructs an interference frame associated therewith, and synchronously drives the information release LED array and the interference LED array through an amplifying circuit, so that mobile phone users receive the strip image after interference; the mobile phone user uses the code shift indicator value negotiated with the information release center to demodulate and decode the strip information, and obtains the information pushed to the mobile phone user by the information release center. A user can only demodulate and decode the strip information with the code shift light interference using the code shift indicator value of the user, and cannot decode the strip information of other mobile phone users. Therefore, the OCC system can use the broadcast visible light channel to encrypt the user information at the physical layer, so that the privacy of the user information is guaranteed, and the directional release and directional push functions of the information are expanded. The present invention is simple, the software and hardware are easy to implement, and it is convenient to upgrade and transform the existing system.

[0020] The present invention utilizes physical layer encryption technology to add differential optical interference to the load information of different users within the same LED light source coverage area according to the code shift indication value negotiated between the user and the information release center. Each user demodulates and decodes the strip information with optical interference according to its own code shift indication value. When there are multiple users within the LED light source coverage area, the privacy of each user's information can be effectively guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the OCC-based code-shift optical jamming private communication system of the present invention.

[0022] Figure 2a Schematic diagram of the alternating arrangement of the lamp beads in the information release LED array and the lamp beads in the interference LED array; Figure 2b This is a schematic diagram of the alternating arrangement of the lamp beads in the information release LED array and the lamp beads in the interference LED array in a circular pattern.

[0023] Figure 3 This is the software flow chart of the information release center control layer.

[0024] Figure 4 This is the flow chart of the information release software of the information release center.

[0025] Figure 5 Figure 2 is a frame structure diagram of information frames, control frames, and associated interference frames.

[0026] Figure 6 Schematic diagram of interference frames associated with constructing information frames.

[0027] Figure 7 Registration flow chart for mobile phone users.

[0028] Figure 8 This is a diagram of the registration application information structure.

[0029] Figure 9 Flowchart of demodulating and decoding information released for mobile phone users.

[0030] Figure 10 Schematic diagram of decoding payload information using code shift indicator values. DETAILED DESCRIPTION

[0031] To make the technical solution and advantages of the present invention more clear, the technical solution of the present invention will be fully and clearly described below in conjunction with the accompanying drawings of the examples of the present invention. It should be noted that if there are any processes or symbols that are not specifically described below, they can be implemented by those skilled in the art with reference to the existing technology. The key to the present invention lies in the technical solution proposed for the private communication method. Any software or programming content involved can be implemented by those skilled in the art with reference to the existing technology.

[0032] The present invention is described in detail below by taking an example where a patient registers as a mobile phone user and waits for treatment in a hospital.

[0033] After a mobile phone user registers online or offline, the registration information (patient's name, ID number, registered department, and consultation time) and the patient's queue status during the consultation period will be sent to the information storage module of the information release center through the network; the patient (carrying a mobile phone) enters the coverage area of ​​the LED array light, opens the mobile phone APP, and initiates a registration application; after receiving the registration application, the information release center executes the registration process, and then searches the information storage module for the patient's registration information and current queue status through the main control module. The queue status of the consultation department can be released to the patient in real time through the LED array, and other patients will not be able to see the patient's information, nor will other patients' consultation information be pushed to the patient.

[0034] like Figure 1 As shown, the OCC-based code-shift light interference private communication system of the present invention includes an information release center and mobile phone users. The information release center includes a main control module, a registration and heartbeat packet detection module, an information storage module, a signal amplification circuit and an LED array. Unlike the existing communication system, in addition to the original information release LED array, an interference LED array is also provided in the LED array, and the lamp beads of the information release LED array and the lamp beads of the interference LED array are arranged alternately.

[0035] The main control module serves as the core of the information release center. It receives registration application information and heartbeat packets sent by mobile phone users through an uplink and sends them to the registration and heartbeat packet detection module to complete functions such as user information registration, negotiated code shift indication value, and heartbeat packet detection. The information storage module accesses the server to obtain the user's information to be released. In the information release process, the main control module encodes the user's information to be released, encapsulates the control frame and information frame, and performs OOK modulation. The modulated control frame signal or information frame signal drives the information release LED array to emit light through a signal amplification circuit. Different from the existing technology, the registration application information includes a code shift indication value in addition to user information. The main control module also uses the code shift indication value to construct an interference frame associated with the control frame and an interference frame associated with the information frame, respectively, to achieve synchronous OOK modulation of the control frame and the interference frame associated with it, and synchronous OOK modulation of the information frame and the interference frame associated with it; the modulated control frame signal and the interference frame signal associated with it synchronously drive the information release LED array and the interference LED array to emit light through the signal amplification circuit, and the modulated information frame signal and the interference frame signal associated with it synchronously drive the information release LED array and the interference LED array to emit light through the signal amplification circuit, respectively, to achieve the output of the light-added interference signal.

[0036] Mobile phone users use a CMOS image sensor to capture the strip image formed by the light emitted by the LED array through the visible light channel, pre-process the strip image and perform multi-amplitude demodulation, and locate it by the frame header and end symbol to obtain a frame of complete payload data containing code elements 0, 1, and 2; use the code shift indicator value to perform staggered decoding to eliminate light interference, and then perform secondary decoding to obtain the information to be released and display it on the mobile phone screen; at the same time, the mobile phone user also sends registration application information, code shift indicator value and heartbeat packet to the main control module of the information release center through the uplink.

[0037] The LEDs in the information-distributing LED array are arranged alternately with the LEDs in the interference LED array. The alternating arrangement includes, but is not limited to, strip-shaped and circular patterns. The information-distributing LED array and the interference LED array have the same number of LEDs, ensuring that the two LED arrays emit the same intensity. Furthermore, a lampshade is added to the exterior of the LED array to ensure that the mobile phone camera is unaware of any differences between the LED array's data frame (control frame or information frame) and the interference frame.

[0038] Figure 2a The lamp beads in the information release LED array and the lamp beads in the interference LED array are arranged alternately in strips. The lamp beads in odd columns constitute the information release LED array, and the lamp beads in even columns constitute the interference LED array. The lamp beads in odd columns and even columns are connected in series and are all powered by a constant current source. Figure 2b The LEDs in the information-distributing LED array and the interference LED array are arranged in a ring-like pattern. The odd-numbered LEDs form the information-distributing array, while the even-numbered LEDs form the interference LED array. The odd-numbered and even-numbered LEDs are connected in series and powered by a constant current source. The solid lines in the figure represent the series lines between the LEDs.

[0039] Figure 3 This is a software flow chart for the control layer of the information publishing center. The control layer performs tasks such as heartbeat packet detection, code shift indicator value and user sequence number allocation, and control frame encapsulation. The specific steps are as follows:

[0040] Step 1: Configure and initialize the parameters of the main control module of the information release center, configure GPIO and serial port to connect the signal amplification circuit and uplink, drive the Ethernet interface module to connect the information storage module to obtain the user's information to be released; initialize the timer to detect the interval time of the received heartbeat packet.

[0041] Step 2: Check whether the wireless channel uplink information is received. If no information is received, continue with step 2; if information is received, proceed to step 3.

[0042] Step 3: Determine whether the received information is a registration application or a heartbeat packet. If it is a heartbeat packet, record the user's heartbeat packet interval and delete registered users who have not sent a heartbeat packet within the specified time; if it is a registration application, proceed to step 4.

[0043] Step 4: Check whether the code shift indicator value in the registration application information has been assigned. If it has been assigned, reallocate the code shift indicator value and send it to the mobile phone user via the downlink, then proceed to step 5. If it has not been assigned, proceed directly to step 5.

[0044] Step 5: Assign a user serial number to the user who sent the registration application information.

[0045] Step 6: Encapsulate the control frame according to the frame structure. The payload of the control frame is "#NN", where NN is the negotiated code shift indicator value. Since UTF-8 encoding contains 8 bits per byte, the payload #NN occupies 3 bytes, totaling 24 bits. Since Manchester encoding contains 16 bits per byte, the payload #NN of the control frame occupies 3 bytes, totaling 48 bits.

[0046] Step 7: Constructing an interference frame associated with the control frame. The payload of the interference frame is the code shift information of the control frame payload, and the number of code shift bits is determined by the code shift indicator value in the registration application information.

[0047] Step 8: Synchronize the OOK modulation control frame and the interference frame associated with it, and simultaneously drive the information release LED array and the interference LED array through the signal amplification circuit to release the interference control information, and return to execute step 2.

[0048] Figure 4 This is a software flow chart for publishing information to be published by users of the information publishing center. The information publishing center polls the queue of pending information of registered mobile phone users and publishes information in a multiplexed manner. The specific steps are as follows:

[0049] Step 1: Check whether the parameter configuration and initialization of the information release center main control module are complete. If not, continue with step 1; if completed, proceed to step 2.

[0050] Step 2: Check whether there are new registered users. If no new users are registered, proceed to step 3; if a new user is registered, access the server to query the new user's pending information and add the pending information to the information release queue.

[0051] Step 3: Poll the queue of registered users to be published and extract the information to be published. The polling is performed in the order of the user serial numbers assigned by the information publishing center. Deregistered users are not within the polling range. Each polling only extracts one information frame of information data to be published for one user.

[0052] Step 4: Encapsulate the information frame according to the frame structure. First, encode the information data in UTF-8, then convert it into binary data, and finally expand it into Manchester code to obtain the payload. Then, encapsulate the encoded payload into a frame according to the frame structure.

[0053] Step 5: Construct an interference frame associated with the information frame. The payload of the interference frame is the code shift information of the information frame payload, and the number of code shift bits is determined by the code shift indication value negotiated between the user and the information publishing center.

[0054] Step 6: Synchronize the OOK-modulated information frame and its associated interference frame. Through the signal amplification circuit, drive the information publishing LED array and the interference LED array simultaneously to publish the information to be published with interference, and then return to execute Step 2.

[0055] The frame structures of the control frame, the information frame, and the interference frame are the same. As Figure 5 shown, the frame structure consists of a frame header, a user serial number, a packet serial number, a payload, and an end symbol arranged in sequence. Among them, the frame header consists of 6 bits, which is "111110" to indicate the start of the frame, and the end symbol is "0" to indicate the end of the frame; the user serial number consists of 10 bits to indicate the user attribution of the frame data. When the user receives the frame data, the user serial number is parsed to determine whether to continue demodulation and decoding or discard the frame; the packet serial number has 14 bits to represent the sorting of the frame data in all data frames of the information to be published by the user; the payload has 48 bits, which is composed of "#NN" or the bit sequence after Manchester encoding of the information to be published or the interference information bit sequence.

[0056] The information to be published consists of Chinese characters, English characters, and punctuation marks. Among them, each Chinese character and Chinese punctuation mark occupies 3 bytes, and each English character and English punctuation mark occupies 1 byte. Therefore, one information frame can transmit 1 Chinese character or 1 Chinese punctuation mark, or 3 English characters or 3 English punctuation marks.

[0057] The code shift information bit sequence of the interference frame associated with the control frame is obtained by shifting each bit of the payload bit sequence of the control frame according to the code shift indication value, and the code shift information bit sequence of the interference frame associated with the information frame is obtained by shifting each bit of the bit sequence of the information frame payload according to the code shift indication value. If the code shift indication value K agreed upon by the information publishing center and the mobile phone user is 4, as Figure 6 shown, taking the Chinese character "中" in the information to be published as an example. The specific steps for constructing the code shift information are as follows:

[0058] Step 1: The UTF-8 encoding of "中" occupies 3 bytes, and its encoding is: 0xE4B8AD. When converted into binary data, it is represented as: 0b111001001011100010101101;

[0059] Step 2: After Manchester encoding, expand it to a 48-bit bit stream: 0b101010010110010110011010100101011001100110100110;

[0060] Step 3: According to the code shift indicator value K=4, the first 4 bits of the code shift information are filled with 0101, and the bits from the 5th to the 48th are filled with the "medium" Manchester encoded bit sequence. After filling to 48 bits, the remaining 4 bits, i.e. 0110, can be deleted.

[0061] Except that the payload is replaced by code shift information, the rest of the interference frame is consistent with its associated control frame or information frame.

[0062] When the corresponding bits of the code shift information and the control frame or information frame associated with it are both 1, the information release LED array and the interference LED array light up at the same time; when a bit of the code shift information is 1 and the corresponding bit of the control frame or information frame associated with it is 0, only the interference LED array lights up; when a bit of the control frame or information frame is 1 and the corresponding bit of the code shift information is 0, only the information release LED array lights up; when the corresponding bits of the code shift information and the control frame or information frame associated with it are both 0, neither the information release LED array nor the interference LED array lights up.

[0063] Figure 7 This is a registration flow chart for mobile phone users. When a mobile phone user enters the LED light source coverage area, they open the mobile app and start the mobile phone registration process. First, they set the camera parameters and permissions, and then send the user registration application information.

[0064] The data structure of the mobile phone user registration application information consists of two parts: user information and code shift indication value, the structure is as follows Figure 8 As shown; wherein, the user information includes name and ID number, and the code shift indicator value is a random integer in the range of 1-24.

[0065] The mobile phone user sends the registration application information, collects and processes the image, and completes the registration process. The specific steps are as follows:

[0066] Step 1: Obtain a strip image. Use the mobile phone camera to capture the original image, extract the region of interest from the original image, and obtain a strip image.

[0067] Step 2: Image preprocessing. The stripe image is preprocessed to obtain a stripe grayscale image. When the information release LED array and the interference LED array are simultaneously lit, the single stripe is a bright stripe. When only the interference LED array or the information release LED array is lit, the single stripe is a gray stripe. When both the information release LED array and the interference LED array are off, the single stripe is a dark stripe.

[0068] Step 3: Preliminary analysis of the strip information of the strip grayscale image. If the received frame of strip grayscale image contains two complete frame headers, it is determined that the strip grayscale image contains a complete frame of strip information, and step 4 is executed; if it only contains one complete frame header or does not contain a frame header, the strip grayscale image does not contain a complete frame of strip information, and return to execute step 1.

[0069] Step 4: Demodulate the stripe information. According to the stripe width of the frame header, determine the single stripe width (the frame header is 111110, the stripe width is 6 code elements, and the single stripe width is one code element), and set the gray threshold to L l ~L g , the grayscale of a single strip is less than L l , greater than or equal to L l Less than or equal to L g , greater than L g When , it is demodulated into three types of code element values ​​0, 1, and 2 respectively.

[0070] Step 5: Decode the payload information using the registered code shift indicator value.

[0071] Step 6: If the load information data decoded in step 5 meets the format of #NN, it is determined that the frame carrying the load is a control frame, and the load information data is the code shift indication value transmitted to the current user by the information release center, and then step 7 is executed; if the load information data decoded in step 5 does not meet the format of #NN, it is determined that the frame carrying the load is a data frame of another user, and the load information data is the information transmitted to the other user by the information release center, and then the process returns to step 1.

[0072] Step 7: Determine the bit sequence of the user number from the frame structure, decode the bit sequence, obtain the user number of the current user, and register the user number and the code shift indicator value.

[0073] Step 8: Set the Registration Complete Indicator. This step indicates that the mobile user has negotiated the code shift indicator value with the information release center and obtained their user serial number, completing registration. Therefore, the Registration Complete Indicator is set to 1. When the mobile user performs the demodulation, decoding, and information release process, they must check whether the Registration Complete Indicator is 1 to determine whether to continue with the demodulation, decoding, and information release process.

[0074] Step 9: Start the heartbeat packet sending mode. The data structure of the heartbeat packet is consistent with the data structure of the registration application information, such as Figure 8 After the heartbeat packet sending mode is started, the mobile phone user sends a heartbeat packet to the information release center via the uplink every 5 seconds. When the mobile phone APP cannot receive the stripe information or is closed, the sending of the heartbeat packet is stopped.

[0075] Figure 9 Flowchart of demodulating and decoding information for mobile phone users. After completing the registration process on the mobile APP, the process of demodulating and decoding information is entered to receive and process the information sent to the user by the information release center. The specific steps are as follows:

[0076] Step 1: Determine whether registration is complete by checking the indication bit. If the registration completion indicator bit is 1, registration is complete and step 2 is executed. If the registration completion indicator bit is 0, registration is not complete and step 1 is continued until registration is determined to be complete.

[0077] Step 2: Obtaining a strip image: Use a camera to capture an original image, extract the region of interest of the original image, and obtain a strip image.

[0078] Step 3: Image preprocessing: Preprocess the image of the region of interest to obtain a strip grayscale image.

[0079] Step 4: Preliminary analysis of the strip information of the strip grayscale image. If the received frame of strip grayscale image contains two complete frame headers, it is determined that the strip grayscale image contains a complete frame of strip information, and step 5 is executed; if it only contains one complete frame header or does not contain a frame header, the strip grayscale image does not contain a complete frame of strip information, and return to step 2.

[0080] Step 5: Demodulate the strip. According to the strip width of the frame header, determine the width of a single strip, and demodulate the strip into three types of code values ​​0, 1, and 2 according to the set gray threshold. Set the gray threshold to L l ~L g , the grayscale of a single strip is less than L l , greater than or equal to L l Less than or equal to L g , greater than L g When , it is demodulated into three types of code element values ​​0, 1, and 2 respectively.

[0081] Step 6: Determine the bit sequence of the user number from the frame structure, decode the bit sequence to obtain the user number, and if the user number matches the user number assigned to the user by the information release center, determine that this frame is an information frame sent by the information release center to the user, and execute step 7; otherwise, determine that this frame is not an information frame sent by the information release center to the user, and return to execute step 2.

[0082] Step 7: Determine the bit sequence of the payload information from the frame structure, and use the code shift indicator value to decode the payload information of the information frame.

[0083] Step 8: Determine the bit sequence of the packet number from the frame structure, decode the packet number, and display the decoded payload information in order on the mobile phone app.

[0084] The demodulation and decoding methods for the control frame or information frame payload information are the same. Taking the code shift indication value K = 4 and the transmitted data being the Chinese character "中" as an example, as Figure 10 shown, the specific steps are as follows:

[0085] Step 1: According to the set grayscale threshold, demodulate each single strip in the strip information corresponding to the payload into a code element value of type 0, 1, or 2, and obtain a complete frame of payload encoded data;

[0086] 1) If the single strip is a dark stripe, demodulate it as 0 (both the information frame data and the interference frame data are 0);

[0087] 2) If the single strip is a gray stripe, demodulate it as 1 (one of the information frame data and the interference frame data is 0 and the other is 1);

[0088] 3) If the single strip is a bright stripe, demodulate it as 2 (both the information frame data and the interference frame data are 1);

[0089] Step 2: Encodingly group the payload encoded data according to the negotiated code shift indication value K = 4. Each group contains the same number of code elements as the code shift indication value K, and group them sequentially from front to back. The last group may have less than K code elements;

[0090] Step 3: According to the code shift indication value K = 4, subtract the first group data 0101 of the interference frame payload from the first group data 1111 of the encoding group to obtain the first group data 1010 of the information frame payload; use the first group data 1010 of the information frame payload as the second group data of the interference frame payload; subtract the second group data of the interference frame payload from the second group data 2011 of the encoding group to obtain the second group data 1001 of the information frame payload; use the second group data 1001 of the information frame payload as the third group data of the interference frame payload, and subtract the third group data of the interference frame payload from the third group data 1111 of the encoding group to obtain the third group data 0110 of the information frame payload; and so on, to obtain the Manchester encoded data 0b1010 10010110 0101 ...... of the information frame payload when the code shift indication value K = 4.

[0091] Step 4: Perform Manchester decoding on the Manchester encoded data of the information frame payload to obtain the UTF-8 encoded data 0b111001001011100010101101 transmitted by the information frame payload, and decode the UTF-8 encoded data to obtain the information of the information frame payload.

[0092] Step 5: Repeat Step 1 to Step 4 to demodulate and decode all the strip information with optical interference sent by the information publishing center to the user to obtain the information to be published by the user.

[0093] The present invention utilizes the code shift indicator value negotiated between the information release center and the mobile phone user to construct an interference frame of the control frame or information frame, and realizes synchronous OOK modulation of the control frame or information frame and the interference frame associated therewith; the modulated control frame signal or information frame signal and the interference frame signal synchronously drive the information release LED array and the interference LED array arranged alternately to emit light; the mobile phone user obtains the interference strip information within the direct or reflected coverage range of the LED, and utilizes the code shift indicator value to demodulate and decode, and obtains the information transmitted to the user by the control frame and the information frame; the mobile phone user sends a heartbeat packet through the uplink to ensure that the information release center knows that the user is still in the information receiving state; the present invention utilizes the constructed interference frame to increase the differentiated light interference between different users on the visible light broadcast channel, and each user can only decode the information of the user himself, thereby solving the privacy problem of information received by multiple users. The method is simple, the software and hardware are easy to implement, and it is convenient to upgrade and transform the existing system.

[0094] The uplink includes but is not limited to wireless communication methods such as mobile communication, WIFI, and Bluetooth.

Claims

1. A code-shifted optical interference private communication system based on OCC, comprising an information release center and mobile phone users. In the information release center, a main control module encodes the information to be released by the mobile phone user and encapsulates the control frame and information frame. The LED array is composed of lamp beads of the information release LED array and lamp beads of the interference LED array arranged alternately. The main control module uses the code shift indication value negotiated by the mobile phone user and the information release center to construct interference frames associated with the control frame and the information frame respectively, and realizes synchronous OOK modulation of the control frame and the interference frame associated therewith, and the information frame and the interference frame associated therewith; wherein the load of the interference frame associated with the control frame is the code shift information of the control frame load, and the load of the interference frame associated with the information frame is the code shift information of the information frame load, and the number of code shift bits is equal to the code shift indication value; the modulated control frame signal or information frame signal is synchronized with the interference frame signal to drive the information release LED array and the interference LED array to emit light respectively; the mobile phone user collects the original image formed by the LED array light emission and extracts the strip image, uses the code shift indication value to perform offset demodulation and decoding to remove light interference to obtain the information to be released by the user and display it on the mobile phone screen; the code shift indication value is a random integer in the range of 1-24.

2. The OCC-based code-shifted optical jamming private communication system according to claim 1 is characterized in that The lamp beads in the information release LED array and the lamp beads in the interference LED array are arranged alternately in strips or in rings.

3. The OCC-based code-shifted optical jamming private communication system according to claim 1 is characterized in that The control frame, information frame and interference frame have the same frame structure, which is composed of a frame header, a user sequence number, a packet sequence number, a payload and an end symbol arranged in sequence.

4. The OCC-based code-shifted optical jamming private communication system according to claim 3 is characterized in that The frame header consists of 6 bits, which are "111110", and the end character is "0".

5. The OCC-based code-shifted optical jamming private communication system according to claim 3 is characterized in that The payload of the control frame is a bit sequence of "#NN" after Manchester encoding, where NN is the code shift indicator value; the payload of the information frame is a bit sequence obtained by first encoding the information to be published in UTF-8, then converting it into binary data, and finally expanding it into Manchester encoding.

6. The OCC-based code-shifted optical jamming private communication system according to claim 3 is characterized in that Assume that the code shift indication value is K. The code shift information of the control frame payload is composed of the control frame payload smoothly shifted by K bits, filling the first K bits, and discarding the last K bits. The code shift information of the information frame payload is composed of the information frame payload smoothly shifted by K bits, filling the first K bits, and discarding the last K bits.

7. The OCC-based code-shifted optical jamming private communication system according to claim 6, characterized in that When the code shift indicator value K is an even number, the first K bits are filled with 0101…01; when the code shift indicator value K is an odd number, the first K-1 bits are filled with 0101…01, and the Kth bit is filled with 0.

8. The OCC-based code-shifted optical jamming private communication system according to claim 6, characterized in that The method for the mobile phone user to obtain the information to be published by the user by performing staggered demodulation and decoding using the code shift indicator value is as follows: Step 1: Preprocess the strip image to obtain a strip grayscale image. According to the set grayscale threshold, demodulate each single strip in the strip information corresponding to the payload into a code element value of 0, 1 or 2 to obtain a complete frame of payload data; Step 2: Encode and group the payload data according to the code shift indicator value K. Each group contains K code elements, and the groups are grouped from the front to the back. The number of code elements in the last group is less than or equal to K. Step 3: subtract the first group of data of the interference frame payload from the first group of data of the coded packet to obtain the first group of data of the information frame payload; use the first group of data of the information frame payload as the second group of data of the interference frame payload; subtract the second group of data of the interference frame payload from the second group of data of the coded packet to obtain the second group of data of the information frame payload; use the second group of data of the information frame payload as the third group of data of the interference frame payload, and subtract the third group of data of the interference frame payload from the third group of data of the coded packet to obtain the third group of data of the information frame payload; and so on, to obtain the Manchester coded data of the information frame payload; Step 4: Manchester decode the Manchester-encoded data in the information frame payload, and then perform UTF-8 decoding on the Manchester-decoded data to obtain the data information transmitted in this frame; Repeat steps 1 to 4 to decode and demodulate all the strip information with optical interference sent to the user by the information release center to obtain the information to be released by the user.

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