Multi-device rapid pairing and seamless screen projection switching system based on ultrasonic signals

Abstract

The invention relates to the field of multi-device screen projection, in particular to a multi-device rapid pairing and seamless screen projection switching system based on ultrasonic signals, which comprises an ultrasonic processing module, a switching module, a data transmission module and an intelligent control processing module which are in wireless communication connection, wherein the ultrasonic processing module is used for transmitting and receiving ultrasonic signals through a phase modulation technology and a self-adaptive filtering technology, and pairing the ultrasonic signals; the switching module is used for switching screen projection connection after successful pairing; the data transmission module is used for establishing a temporary data transmission channel for data transmission; and the intelligent control processing module is used for receiving a screen projection request through a screen projection system optimization algorithm, a time window and a priority algorithm, and dynamically adjusting screen projection resource allocation. According to the invention, efficient pairing and switching of multiple devices can be realized, reliable information transmission and error correction are guaranteed, screen projection resource management and switching are more flexible, and good user experience and adaptability are improved.

Description

Technical Field

[0001] The present invention relates to the field of multi-device screen projection, and in particular to a multi-device fast pairing and seamless screen projection switching system based on ultrasonic signals. Background Art

[0002] In today's digital age, the demand for multi-device collaboration and screen projection is growing. With the popularity of smart devices, people often need to project screens between different devices in order to better share content, make presentations, or enjoy multimedia entertainment. Traditional screen projection methods usually rely on specific wireless communication technologies and usually require manual switching of devices. These methods have certain limitations in multi-device scenarios, resulting in inconvenience and low efficiency in use. Traditional wireless screen projection technology is susceptible to interference and misconnection, resulting in erroneous or unstable data transmission. During the screen switching process, there are often significant delays or black screens, affecting the user experience. In order to solve these problems, a more convenient, efficient, and stable multi-device screen projection solution is needed. Summary of the invention

[0003] To solve the above problems, the present invention provides a multi-device fast pairing and seamless screen projection switching system based on ultrasonic signals, which can efficiently pair and switch multiple devices, ensure reliable information transmission and error correction, make screen projection resource management and switching more flexible, and improve good user experience and adaptability.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A multi-device fast pairing and seamless screen switching system based on ultrasonic signals, comprising: an ultrasonic processing module connected by wireless communication, a switching module, a data transmission module and an intelligent control processing module, wherein:

[0006] The ultrasonic processing module is used to generate the sending and receiving of ultrasonic signals through phase modulation technology and adaptive filtering technology, and perform pairing;

[0007] The switching module is used to switch the screen projection connection after successful pairing;

[0008] The data transmission module is used to establish a temporary data transmission channel for data transmission;

[0009] The intelligent control processing module is used to receive screen projection requests through the screen projection system optimization algorithm, time window and priority algorithm, and dynamically adjust the screen projection resource allocation.

[0010] Furthermore, the sending and receiving of ultrasonic signals are generated by phase modulation technology and adaptive filtering technology, and paired; comprising the following steps:

[0011] A1: The device ID and other information are converted into the original binary information of the binary digital sequence through the cyclic redundancy check algorithm, and error correction coding is performed and redundant information is added;

[0012] A2: According to the carrier frequency of the ultrasound, different phase states are divided to represent different binary values. For each bit in the binary sequence after error correction coding, the phase of the ultrasound signal is changed according to the binary value.

[0013] A3: The phase modulated signal is sent out through the ultrasonic transmitter, and the ultrasonic receiver receives the signal and processes the received signal through the recursive least squares algorithm;

[0014] A4: The filtered signal is subjected to coherent detection with a locally generated reference signal having the same carrier frequency and phase as the transmitting end. The coherent detection process is performed by a multiplier and an integrator.

[0015] A5: Decode the signal after coherent detection. According to the phase modulation rules, restore the different phase states to corresponding binary values ​​and remove the redundant information added by the error correction coding.

[0016] Furthermore, the method of processing the received signal by a recursive least squares algorithm comprises the following steps:

[0017] A31: By sampling the received ultrasonic signal, the continuous ultrasonic signal r(t) is converted into a discrete time signal r[n], where n represents the sequence number of the sampling point, the filter coefficient vector w(0) is a small random vector, and the filter length L and the error covariance matrix P(0) are initialized to a diagonal matrix;

[0018] A32: At each sampling point n, in the process of calculating the filter output, the formula for the input signal vector is: x(n) = [r[n], r[n-1], ..., r[n-L+1]] T , the filter output formula is: y(n) = w(n-1) T x(n), where: T represents transpose;

[0019] A33: In ultrasonic signal processing, if there is a reference signal, the expected signal is the value of the reference signal at the current sampling point; if there is no reference signal, the expected signal is determined based on prior knowledge. Let the expected signal be d(n), the error formula is: e(n) = d(n) - y(n), and the gain vector formula is:

[0020]

[0021] Where λ is the forgetting factor, and the formula for updating the filter coefficient is: w(n)=w(n-1)+k(n)e(n),

[0022] The formula for updating the error covariance matrix is:

[0023] A34: Repeat steps A32 and A33, and continuously update the filter coefficients as the sampling points increase, so that the output of the filter gradually approaches the desired signal.

[0024] Furthermore, the ultrasonic receiver is an ultrasonic transducer that converts ultrasonic signals into electrical signals. The received continuous ultrasonic signal is discretized according to the sampling frequency to obtain a discrete-time signal sequence. The device information obtained by decoding is compared with the locally cached device list. If the decoded device ID exists in the local device list, it is considered to be a legitimate device and a connection operation is performed. During the connection process, a confirmation signal is sent to the access device. After the access device receives and confirms it, it confirms that the pairing is successful.

[0025] Furthermore, when multiple devices process pairing requests in parallel, a dictionary is created to store the pairing request information of all devices to be paired. According to the multi-threaded parallel computing framework, the collected pairing requests are assigned to different computing units for processing through polling allocation. Each computing unit starts to process the assigned pairing requests at the same time, and records the pairing status of each device according to a two-dimensional table. During the parallel processing, each computing unit updates the pairing status of the corresponding device in the status record table in real time according to the processing results, and devices that have not been successfully paired remain in a waiting state.

[0026] Furthermore, the switching of the screen projection connection after the pairing is successful comprises the following steps:

[0027] B1: When confirming the switch of the screen projection connection, the user triggers the switch request through the operation interface, and the screen projection device automatically determines whether the screen projection needs to be switched according to the preset conditions. For example, when the screen projection device detects that a specific application is started or a specific event occurs, the screen projection switching process is automatically started. The screen projection device selects the appropriate access device according to the current environment and needs;

[0028] B2: After the second access device confirms that the connection between the current projection device and the first access device is closed, it performs pairing and projection connection through coding, phase modulation technology, adaptive filtering technology and coherent detection technology;

[0029] B3: During the switching process, after the second access device and the projection device are paired successfully, a part of the projection content is cached in advance. During the process, after the second access device is paired successfully and before sending a confirmation request for pairing, the content to be projected begins to be cached. When the pairing request is confirmed to be successful, the projection device immediately plays the content from the cache;

[0030] B4: For single video data, use the smooth transition technology of the video stream to gradually fade in the new projection content and fade out the old projection content when switching; for single audio data, use the cross-fade technology to gradually reduce the volume of the old audio and gradually increase the volume of the new audio.

[0031] Furthermore, during the pairing and connection establishment process, the access device and the projection device negotiate parameters to determine a unified projection resolution, frame rate, audio format, and video format based on the capabilities of both devices and the supported projection parameters. After confirming the pairing, the projection device and the access device encode and compress the content to be projected and send it to the projection device through the established connection channel. The projection device receives and decodes the projection content and then displays and plays it.

[0032] Furthermore, the successfully paired devices are preprocessed, and a bandwidth share is allocated to each successfully paired device according to the needs of screen projection and the priority of the device. The bandwidth usage of each device is limited by network traffic shaping technology. An independent buffer space is allocated to each successfully paired device by dynamic memory allocation technology. The buffer is managed by a circular buffer data structure. According to the priority of the device and the complexity of the screen projection task, processor time is allocated to the successfully paired devices by a time slice round-robin scheduling algorithm. Predictive preloading is performed according to the user's behavior patterns and historical records. The preloaded content is stored by the least recently used algorithm in the cache replacement algorithm, and the preloaded content is cached in the memory or storage medium of the local device. The status of the screen projection hardware is detected by obtaining the hardware status information according to the interface, and the status of the screen projection software is detected by communicating with the device manager through the developer server of the application. If an abnormal hardware or software status is detected, appropriate processing measures are taken, and the results of the device status detection are recorded in the log file.

[0033] Furthermore, in the establishment of a temporary data transmission channel for data transmission, the data transmission protocol and wireless communication technology are selected according to the setting selection interface of the screen projection application. The data transmission protocol includes UDP or TCP, and the wireless communication technology includes Wi-Fi Direct, Bluetooth or DLNA. The selection is recorded and used. If the user wants to switch the wireless communication technology or transmission protocol during the screen projection process, a switching request is issued through the setting interface of the application. After receiving the user's switching request, the application suspends the current data transmission and prepares for switching. Encryption is performed through the WPA2 security protocol during the screen projection connection.

[0034] Furthermore, the method of receiving a screen projection request through a screen projection system optimization algorithm, a time window and a priority algorithm, and dynamically adjusting the allocation of screen projection resources comprises the following steps:

[0035] C1: The screen projection system continuously listens to screen projection requests from various devices, monitors the status of the active device currently performing screen projection in real time, sets a fixed-length time window, calculates the relationship between the arrival time and the current time window for each new screen projection request, and adjusts the priority according to the position of the request in the time window;

[0036] C2: According to the priority algorithm, the comprehensive priority of each screen projection request is calculated by weighted summation, and all pending screen projection requests are sorted according to the comprehensive priority. If there are multiple requests with the same highest priority, the next access device is determined based on the first-come-first-served principle or random selection. At the same time, the system records these requests with the same priority.

[0037] C3: Continuously evaluate the currently available projection resources and dynamically adjust the allocation of projection resources according to the priority and projection requirements. While adjusting the resource allocation, the system prepares for seamless switching, including preloading the projection content of the newly connected device into the buffer and establishing a communication channel with the new device.

[0038] C4: When the new connected device is ready and the resource allocation adjustment is completed, the system triggers a seamless switching operation. During the switching process, the system gradually transfers the projection output from the current active device to the new connected device. At the same time, the system continues to monitor the performance indicators during the switching process. When a problem occurs, the system automatically adjusts the switching strategy or performs error recovery operations.

[0039] The beneficial effects of the present invention are:

[0040] 1. Use ultrasonic signals to pair devices without relying on traditional complex wireless connection settings, making the pairing process between multiple devices more convenient and faster. Whether in a conference room, home, or other scenarios, users can quickly pair devices without tedious manual settings. When multiple devices request pairing in parallel, multiple pairing requests are processed simultaneously through a parallel computing framework, which greatly improves pairing efficiency and reduces user waiting time. Especially when multiple devices need to project screens at the same time, it can respond quickly to meet the user's multi-device projection needs. After the devices are successfully paired, the projection connection of the current device can be quickly closed and the projection connection of the next device can be started, ensuring that there is no significant delay or black screen during the switching process, providing users with a seamless projection experience.

[0041] 2. The device ID and other information are encoded into ultrasonic signals through phase modulation technology, which can resist the interference of environmental noise to a certain extent. Compared with traditional wireless transmission methods, ultrasonic signals may have better stability and anti-interference in specific environments. The use of error correction coding provides a reliable guarantee for information transmission. Even if some errors occur during the transmission process, the receiving end can detect and correct the errors through error correction coding to ensure the accurate transmission of the device ID and other information. Coherent detection technology further improves the detection accuracy of ultrasonic signals at the receiving end. By performing coherent detection with the locally generated reference signal, useful ultrasonic signals can be effectively extracted from complex environmental signals, enhancing the system's anti-interference ability.

[0042] 3. In the preprocessing stage of successfully paired devices, screen projection resources are pre-allocated, and reasonable resource allocation can be made according to the needs and priorities of different devices. It helps to ensure that each device has sufficient resources to support high-quality screen projection and avoid the decline in screen projection quality due to insufficient resources. Users can freely choose UDP protocol or TCP protocol, as well as Wi-Fi Direct, Bluetooth, and DLNA wireless communication technologies to connect according to their needs, providing users with more choices and flexibility. Different protocols and communication technologies are suitable for different screen projection scenarios, and users can choose according to actual conditions to meet different needs. The screen projection system optimization algorithm determines the next access device through time windows and priority algorithms, and dynamically adjusts the allocation of screen projection resources to ensure seamless switching. This enables the system to reasonably allocate resources according to the priority of the device and the urgency of the request when multiple devices are projected, improving the overall performance of the system and user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of the steps of the ultrasonic treatment module.

[0044] Figure 2 It is a flow chart of the steps for switching modules.

[0045] Figure 3 This is a module diagram of a multi-device fast pairing and seamless screen switching system based on ultrasonic signals. DETAILED DESCRIPTION

[0046] See also Figure 1 , Figure 2 and Figure 3 As shown, the present invention relates to a multi-device fast pairing and seamless screen switching system based on ultrasonic signals, comprising: an ultrasonic processing module, a switching module, a data transmission module and an intelligent control processing module connected by wireless communication, wherein:

[0047] The ultrasonic processing module is used to generate the sending and receiving of ultrasonic signals through phase modulation technology and adaptive filtering technology, and perform pairing;

[0048] The switching module is used to switch the screen projection connection after successful pairing;

[0049] The data transmission module is used to establish a temporary data transmission channel for data transmission;

[0050] The intelligent control processing module is used to receive screen projection requests through the screen projection system optimization algorithm, time window and priority algorithm, and dynamically adjust the screen projection resource allocation.

[0051] Furthermore, the sending and receiving of ultrasonic signals are generated by phase modulation technology and adaptive filtering technology, and paired; comprising the following steps:

[0052] A1: The device ID and other information are converted into the original binary information of the binary digital sequence through the cyclic redundancy check error correction coding algorithm, and error correction coding is performed and redundant information is added;

[0053] A2: According to the carrier frequency of the ultrasound, different phase states are divided to represent different binary values. For each bit in the binary sequence after error correction coding, the phase of the ultrasound signal is changed according to the binary value.

[0054] A3: The phase modulated signal is sent out through the ultrasonic transmitter, and the ultrasonic receiver receives the signal and processes the received signal through the recursive least squares algorithm;

[0055] A4: The filtered signal is subjected to coherent detection with a locally generated reference signal having the same carrier frequency and phase as the transmitting end. The coherent detection process is performed by a multiplier and an integrator.

[0056] A5: Decode the signal after coherent detection. According to the phase modulation rules, restore the different phase states to corresponding binary values ​​and remove the redundant information added by the error correction coding.

[0057] Specifically, in step A1, cyclic redundancy check is used to detect and correct errors in data transmission. It is a method of error correction coding based on the principle of polynomial division. Without increasing the channel bandwidth and power, by artificially adding redundant data (bits), the system has the ability to automatically detect or correct errors, thereby improving the reliability of transmission, reducing the bit error rate and data loss rate, and enhancing the stability and security of data transmission. The added redundant information is removed when the receiving end processes the information.

[0058] In step A2, the phase modulation in the binary sequence processing after error correction coding is involved. The phase of the ultrasonic signal is changed by the value of each bit. This method clarifies the correspondence and modulation rules between the bit value in the binary sequence and the phase of the ultrasonic signal. For example, the binary sequence B contains elements b1, b2 to bn, and the value of each element is 0 or 1. After such a setting, the phase modulated signal can be represented by a specific formula s(t) = A*cos(2πfct+φi). Here A represents the signal amplitude, fc is the carrier frequency, t is the time variable, φi is the phase offset, when the value of bi is 0, the corresponding phase φi is 0; and when the value of bi is 1, the phase φi is π.

[0059] In step A4, coherent detection is a technology that uses a known reference signal to perform correlation operations with the received signal to extract useful information. Using a multiplier and an integrator for correlation operations can enhance the amplitude of the useful signal while suppressing noise and interference. For example, the received signal is multiplied by the reference signal and then integrated over a period of time to obtain a correlation value. The size of the correlation value is used to determine whether the received signal contains a valid device ID and other information. If the correlation value exceeds a certain threshold, it is considered that a valid signal is detected, otherwise it is considered to be noise or interference.

[0060] In step A5, the redundant information added by the error correction code is removed to restore the original device ID and other information. Through the cyclic redundancy check, if the remainder is 0, it means that the data is correct, and the check code can be directly removed to restore the original data; if the remainder is not 0, it means that the data is wrong and further error correction measures need to be taken, such as retransmission.

[0061] Furthermore, the method of processing the received signal by a recursive least squares algorithm comprises the following steps:

[0062] A31: By sampling the received ultrasonic signal, the continuous ultrasonic signal r(t) is converted into a discrete time signal r[n], where n represents the sequence number of the sampling point, the filter coefficient vector w(0) is a small random vector, and the filter length L and the error covariance matrix P(0) are initialized to a diagonal matrix;

[0063] A32: At each sampling point n, in the process of calculating the filter output, the formula for the input signal vector is: x(n) = [r[n], r[n-1], ..., r[n-L+1]] T , the filter output formula is: y(n) = w(n-1) T x(n), where: T represents transpose;

[0064] A33: In ultrasonic signal processing, if there is a reference signal, the expected signal is the value of the reference signal at the current sampling point; if there is no reference signal, the expected signal is determined based on prior knowledge. Let the expected signal be d(n), the error formula is: e(n) = d(n) - y(n), and the gain vector formula is:

[0065]

[0066] Where λ is the forgetting factor, and the formula for updating the filter coefficient is: w(n)=w(n-1)+k(n)e(n),

[0067] The formula for updating the error covariance matrix is:

[0068] A34: Repeat steps A32 and A33, and continuously update the filter coefficients as the sampling points increase, so that the output of the filter gradually approaches the desired signal.

[0069] Specifically, in step A31, for a small random vector, according to the filter length set to L, w(0) = [0.1, 0.1, ..., 0.1] T , where the superscript T represents transposition. For the error covariance matrix P(0), for example, P(0) = δI, where δ is a large positive number, set to 100 or greater, and I is an L×L identity matrix.

[0070] In step A33, the recursive least squares algorithm is iteratively used to calculate the error and update the filter coefficients. The forgetting factor λ is usually between 0 and 1.

[0071] In step A34, the output of the filter is gradually approached to the expected signal, thereby realizing adaptive filtering of the received ultrasonic signal. During the whole process, the recursive least squares algorithm continuously adjusts the filter coefficients to adapt to the changes of the ultrasonic signal and the influence of noise, thereby improving the quality and reliability of the signal.

[0072] Furthermore, the ultrasonic receiver is an ultrasonic transducer that converts ultrasonic signals into electrical signals. The received continuous ultrasonic signal is discretized according to the sampling frequency to obtain a discrete-time signal sequence. The device information obtained by decoding is compared with the locally cached device list. If the decoded device ID exists in the local device list, it is considered to be a legitimate device and a connection operation is performed. During the connection process, a confirmation signal is sent to the access device. After the access device receives and confirms it, it confirms that the pairing is successful.

[0073] Specifically, the ultrasonic receiver is in the open state and the ultrasonic signal is continuously received at a fixed sampling frequency. The local device list can be stored in the device's memory or managed by a database. Sending a confirmation signal to the access device during the connection process is to ensure the accuracy and reliability of the connection.

[0074] Furthermore, when multiple devices process pairing requests in parallel, a dictionary is created to store the pairing request information of all devices to be paired. According to the multi-threaded parallel computing framework, the collected pairing requests are assigned to different computing units for processing through polling allocation. Each computing unit starts to process the assigned pairing requests at the same time, and records the pairing status of each device according to a two-dimensional table. During the parallel processing, each computing unit updates the pairing status of the corresponding device in the status record table in real time according to the processing results, and devices that have not been successfully paired remain in a waiting state.

[0075] Specifically, in recording the pairing status of each device through a data structure, a dictionary-type data structure is selected, in which the key is the device identification and the value is the pairing status (successful or unsuccessful). A database can also be used to store pairing status information for subsequent query and management. According to the polling pointer, starting from the head of the queue, the requests are assigned to different computing units in sequence. Each computing unit obtains the pairing request from the assigned location. The two-dimensional table contains fields such as the device identification information (such as device ID, name, etc.), the time of the pairing request, the current pairing status, and the processing result description. In the process of processing the pairing request, each computing unit promptly updates the corresponding records in the two-dimensional table according to the processing results.

[0076] As the parallel computing framework processes each pairing request, the pairing status of the corresponding device is updated in real time. If the pairing status of a device changes from unsuccessful to successful, or from successful to unsuccessful, the record in the data structure or database is updated in time. For devices that are successfully paired, their information is added to the preprocessing queue, which is a first-in-first-out data structure, such as the Queue data type. Devices that are not successfully paired remain in a waiting state. The information of these devices can be stored in a separate waiting queue, or marked as a waiting state in the data structure that records the pairing status. The devices in the waiting queue are checked regularly to see if new pairing conditions are met or whether the pairing request needs to be resent.

[0077] Furthermore, the switching of the screen projection connection after the pairing is successful includes the following steps:

[0078] B1: When confirming the switch of the screen projection connection, the user triggers the switch request through the operation interface, and the screen projection device automatically determines whether the screen projection needs to be switched according to the preset conditions. For example, when the screen projection device detects that a specific application is started or a specific event occurs, the screen projection switching process is automatically started. The screen projection device selects the appropriate access device according to the current environment and needs;

[0079] B2: After the second access device confirms that the connection between the current projection device and the first access device is closed, it performs pairing and projection connection through coding, phase modulation technology, adaptive filtering technology and coherent detection technology;

[0080] B3: During the switching process, after the second access device and the projection device are paired successfully, a part of the projection content is cached in advance. During the process, after the second access device is paired successfully and before sending a confirmation request for pairing, the content to be projected begins to be cached. When the pairing request is confirmed to be successful, the projection device immediately plays the content from the cache;

[0081] B4: For single video data, use the smooth transition technology of the video stream to gradually fade in the new projection content and fade out the old projection content when switching; for single audio data, use the cross-fade technology to gradually reduce the volume of the old audio and gradually increase the volume of the new audio.

[0082] Specifically, in step B1, the screen projection connection is switched by sending an instruction to the access device through the projection device, and the screen projection connection can also be switched by sending an instruction to the projection device through the first access device. For example, when the screen projection needs to be switched, the first access device immediately sends an instruction to close the projection connection to the device currently projecting the screen. After receiving the instruction, the projection device quickly stops the projection output, unoccupies and releases the video output channel, audio output channel and memory. The first access device also notifies the current projection device to save the current projection status information. The first access device refers to the access device that was originally connected to the projection device, and the second access device refers to the access device to be switched after the first access device has stopped projecting when switching the projection connection. The access device is a general term for the first access device or the second access device.

[0083] In step B2, after confirming that the connection between the current projection device and the first access device is closed, the second access device sends an instruction to the projection device to switch the projection connection, encode the pairing request information, and convert it into a signal format suitable for ultrasonic transmission. The pairing request information may include the identifier of the second access device, the requested projection content type, and the projection parameter requirements. Phase modulation technology is used to modulate the pairing request information in binary form onto the ultrasonic signal, and according to the phase modulation rule, the specific pairing request information sequence is converted into a corresponding ultrasonic signal phase change sequence. The encoded pairing request signal is sent out through the ultrasonic transmitter of the second access device, and the power and direction of the transmitter are adjusted to ensure that the signal can cover the area where the projection device is located. The projection device continuously monitors the surrounding ultrasonic signals and uses a special ultrasonic receiver to convert the received ultrasonic signal into an electrical signal. The received signal is preprocessed, including amplification, filtering, and other operations to improve the signal quality and signal-to-noise ratio. The received signal is processed using adaptive filtering and coherent detection technology. By performing coherent detection with the locally generated reference signal, it is determined whether a valid pairing request signal is received. If the coherent detection value exceeds a certain threshold, it is considered that a valid signal is detected, and then the signal is decoded according to the phase modulation rules to extract the pairing request information. The projection device determines whether to agree to the pairing based on the received pairing request information. If the conditions of the pairing request are met, such as sufficient resources to support the projection, good compatibility with the second access device, etc., a confirmation signal is generated. The confirmation signal may include information such as the identification of the projection device, confirmation status, supported projection parameters, etc. The confirmation signal is encoded into an ultrasonic signal and sent back to the second access device through the ultrasonic transmitter of the projection device. If the projection connection is switched by sending an instruction to the access device through the projection device, the technical content in step B2 is still used, and only the sending direction of the ultrasonic signal between devices needs to be adjusted.

[0084] In step B3, the cache technology is used to reduce delays and black screens. For example, for video projection, after pairing is successful and before sending a confirmation request, a few seconds of video data are pre-cached. When switching to the second access device, the content is immediately read from the cache for playback, reducing waiting time.

[0085] In step B4, for the smooth transition technology of the video stream, for example, by adjusting the transparency of the video, a smooth transition between the old and new content is achieved, giving the user a seamless feeling. For audio projection, a cross-fade technology is used to ensure a natural and smooth transition of the audio, avoiding sudden interruptions or jumps in the audio.

[0086] Furthermore, during the pairing and connection establishment process, the access device and the projection device negotiate parameters to determine a unified projection resolution, frame rate, audio format, and video format based on the capabilities of both devices and the supported projection parameters. After confirming the pairing, the projection device and the access device encode and compress the content to be projected and send it to the projection device through the established connection channel. The projection device receives and decodes the projection content and then displays and plays it.

[0087] Specifically, for example, the projection device supports higher resolution and frame rate, and the access device adjusts the projection parameters to obtain better picture quality and smoothness, thereby achieving better picture quality and smoother playback effects, allowing the projection to present a clearer and smoother visual experience, reducing the adverse conditions of picture freezes and blurs.

[0088] Furthermore, the successfully paired devices are preprocessed, and a bandwidth share is allocated to each successfully paired device according to the needs of screen projection and the priority of the device. The bandwidth usage of each device is limited by network traffic shaping technology. An independent buffer space is allocated to each successfully paired device by dynamic memory allocation technology. The buffer is managed by a circular buffer data structure. Processor time is allocated to the successfully paired devices by a time slice round-robin scheduling algorithm according to the priority of the device and the complexity of the screen projection task. Predictive preloading is performed according to the user's behavior patterns and historical records. The preloaded content is stored by the least recently used algorithm in the cache replacement algorithm, and the preloaded content is cached in the memory or storage medium of the screen projection device. The hardware status information is obtained according to the interface to detect the screen projection hardware status. The developer server of the application communicates with the device manager to detect the status of the screen projection software. If an abnormal hardware or software status is detected, appropriate processing measures are taken, and the results of the device status detection are recorded in the log file.

[0089] Specifically, obtain the upload and download speed information of the current network through the network monitoring tool or the interface provided by the system, and evaluate the current network environment and available bandwidth. Use a weighted fair queue algorithm to allocate bandwidth. Network traffic shaping technology can ensure that the screen projection quality of other devices will not be affected by a certain device occupying too much bandwidth. The size of the buffer needs to be determined according to the type, resolution, frame rate and network delay factors of the screen projection content. For example, for high-definition video projection, a larger buffer is generally required to cope with network fluctuations. Dynamic memory allocation technology can allocate the required buffer size at runtime according to the needs of the device. The circular buffer can effectively avoid data overwriting and loss, while improving the efficiency of data reading and writing.

[0090] Monitor the processor load of the local device and use the system performance monitoring tool to obtain information such as processor usage and idle time. In time slice round-robin scheduling, each device is assigned a fixed time slice to perform screen projection related tasks. When the time slice of a device is used up, the processor switches to the next device to perform tasks. For predictive preloaded video screen projection, identify the currently playing video and the video that may be played next. For example, if the user is watching an episode of a TV series, the system can preload the video content of the next episode. Adjust the preloading strategy based on network conditions, device performance, and user behavior factors. The least recently used algorithm in the cache replacement algorithm manages the cache space. When the cache space is full, the least recently used content is selected according to the algorithm for replacement to ensure that the cache always stores the most likely to be accessed content. Detect the status of the screen projection hardware, including the screen, speakers, graphics card, etc. For example, for the screen, check whether the resolution, refresh rate, brightness and other parameters are normal; for the speaker, check whether the volume, channel balance and other parameters are normal; for the graphics card, check whether the video memory usage, graphics processing power and other parameters are normal. If an abnormal hardware or software status is detected, appropriate processing measures are taken. For example, if the screen resolution does not match, the user can be prompted to adjust it; if a fault is found in the screen projection application, the application can be restarted or repaired and installed. Log files are used for subsequent analysis and optimization.

[0091] Furthermore, in the establishment of a temporary data transmission channel for data transmission, the data transmission protocol and wireless communication technology are selected according to the setting selection interface of the screen projection application. The data transmission protocol includes UDP or TCP, and the wireless communication technology includes Wi-Fi Direct, Bluetooth or DLNA. The selection is recorded and used. If the user wants to switch the wireless communication technology or transmission protocol during the screen projection process, a switching request is issued through the setting interface of the application. After receiving the user's switching request, the application suspends the current data transmission and prepares for switching. Encryption is performed through the WPA2 security protocol during the screen projection connection.

[0092] Specifically, a settings interface in the screen projection application allows users to select the protocol and wireless communication technology used for data transmission. For each option, a brief description and recommendation are provided to help users make appropriate choices. For example, the UDP protocol is suitable for scenarios with high real-time requirements but can tolerate a certain amount of data loss, while the TCP protocol is suitable for scenarios with high data reliability requirements. After the user makes a choice in the settings interface, the application records the user's choice and uses it in subsequent data transmission processes.

[0093] Take the Wi-Fi Direct connection process as an example: the two devices that are successfully paired start the Wi-Fi Direct connection process. The devices first perform device discovery, sending probe requests and receiving probe responses to find nearby devices that support Wi-Fi Direct. When the devices discover each other, they pair and connect, a process that usually involves exchanging device information, verifying identities, and establishing a secure connection. Once the connection is successfully established, the two devices can communicate data through the interface provided by Wi-Fi Direct.

[0094] If the user selects the UDP protocol, when using UDP for data transmission, the Real-time Transport Protocol (RTP) is used to transmit audio and video data. RTP provides information such as timestamps and sequence numbers, which helps the receiving end to sort and play the data. For example, for video projection, the sender divides the video data into UDP packets, adds RTP header information, and sends it to the receiving end. The receiving end sorts and plays the data packets according to the timestamp and sequence number in the RTP header, and can try to ensure smooth video playback even in the case of network congestion or packet loss.

[0095] If the user selects the TCP protocol, when using TCP for data transmission, both devices establish a TCP connection and send and receive data through this connection. For example, for file transmission and screen projection, the sender divides the file into TCP data packets and sends them to the receiver through the established TCP connection. The receiver receives the data packets in sequence and reassembles and saves the file after receiving all the data packets.

[0096] Regardless of the transmission protocol and wireless communication technology selected, data needs to be encoded and compressed before sending to reduce the amount of data and improve transmission efficiency. The sender encapsulates the encoded and compressed data according to the selected transmission protocol and sends it to the receiver through the established temporary data transmission channel. After receiving the data, the receiver decapsulates and processes the data according to the selected transmission protocol. For the UDP protocol, the receiver needs to process data packets that may be lost or out of order, and use a packet loss retransmission mechanism or forward error correction technology to recover the lost data. For the TCP protocol, the receiver receives data packets in sequence and reassembles and processes the data after receiving all data packets.

[0097] During the switching process of communication technology and protocol, if you switch from Wi-Fi Direct to Bluetooth, both devices will first disconnect the current Wi-Fi Direct connection, then start the Bluetooth connection process, pair and connect the devices, and after the connection is successfully established, re-establish the data transmission channel according to the transmission protocol selected by the user, and continue data transmission. If UDP switches to TCP, both devices maintain the current wireless communication connection unchanged, and the sender and receiver re-encapsulate and process the data according to the newly selected transmission protocol. The receiver may need to make some additional settings and adjustments to adapt to the new transmission protocol.

[0098] Furthermore, the method of receiving a screen projection request through a screen projection system optimization algorithm, a time window and a priority algorithm, and dynamically adjusting the allocation of screen projection resources comprises the following steps:

[0099] C1: The screen projection system continuously listens to screen projection requests from various devices, monitors the status of the active device currently performing screen projection in real time, sets a fixed-length time window, calculates the relationship between the arrival time and the current time window for each new screen projection request, and adjusts the priority according to the position of the request in the time window;

[0100] C2: According to the priority algorithm, the comprehensive priority of each screen projection request is calculated by weighted summation, and all pending screen projection requests are sorted according to the comprehensive priority. If there are multiple requests with the same highest priority, the next access device is determined based on the first-come-first-served principle or random selection. At the same time, the system records these requests with the same priority.

[0101] C3: Continuously evaluate the currently available projection resources and dynamically adjust the allocation of projection resources according to the priority and projection requirements. While adjusting the resource allocation, the system prepares for seamless switching, including preloading the projection content of the newly connected device into the buffer and establishing a communication channel with the new device.

[0102] C4: When the new connected device is ready and the resource allocation adjustment is completed, the system triggers a seamless switching operation. During the switching process, the system gradually transfers the projection output from the current active device to the new connected device. At the same time, the system continues to monitor the performance indicators during the switching process. When a problem occurs, the system automatically adjusts the switching strategy or performs error recovery operations.

[0103] Specifically, in step C1, when a device issues a screen projection request, the system immediately records information such as the time of the request, the device identification, and the requested screen projection content. The system monitors in real time, including the playback progress of the projection content, network usage, and device performance indicators. For example, by monitoring network traffic and the CPU usage of the device, the resource usage of the currently active device can be understood. Through the time window algorithm, a fixed-length time window is used to observe and evaluate the urgency of the request of the device that is about to be connected. If the request arrives within the time window, it is considered to have a high urgency. For example, if a device issues a request in the first half of the time window, it means that it may be in urgent need of screen projection, and its urgency is relatively high. The closer the request is to the beginning of the time window, the higher the priority.

[0104] In step C2, for the priority algorithm, in addition to the time window factor, other factors are considered to determine the priority of the screen projection request, such as device type, user permissions, or the importance of the screen projection content. For device type, certain high-performance devices or specific types of devices (such as professional presentation equipment) can be given higher priority; in terms of user permissions, administrator users' screen projection requests may have higher priority; the importance of the screen projection content can be determined based on the user's mark or preset rules, for example, the screen projection content marked as an emergency meeting has a higher priority. For the weighted summation method to calculate the comprehensive priority of each screen projection request, a weight is assigned to each priority factor, and then the priority value of each factor is multiplied by the corresponding weight and summed. All pending screen projection requests are sorted according to the comprehensive priority, and the device corresponding to the request with the highest priority will be determined as the next access device. Recording these requests with the same priority is convenient for appropriate adjustments in subsequent resource allocation and switching processes.

[0105] The time window algorithm and priority algorithm of C1 and C2 mentioned above are both independent and cooperative. The time window algorithm focuses on judging the relative urgency of the request from the time dimension, and the priority algorithm comprehensively evaluates the importance and priority of the request. The time window algorithm provides an evaluation dimension based on time urgency for the priority algorithm. In the comprehensive priority calculation, the time window factor is used as one of the factors to participate in the weighted summation, and works together with other priority factors to determine the final priority of the screen projection request. The two work together to determine the next access device. The device corresponding to the high-priority request is more likely to be determined as the next access device, and the time window algorithm can ensure that urgent requests can be processed in a timely manner to a certain extent, and together with the priority algorithm, a more reasonable device access order and resource allocation can be achieved.

[0106] In step C3, the system continuously evaluates the currently available projection resources, including bandwidth, buffer, processor time, etc., and obtains real-time information about these resources through network monitoring tools and system performance monitoring interfaces. If the next access device has a higher priority, the system appropriately reduces resource allocation from the current active device and allocates more resources to the new access device. For example, if the new access device requires higher bandwidth to play high-definition video, the system can reduce the bandwidth usage of the current active device to meet the needs of the new device. Traffic shaping technology can be used to adjust bandwidth allocation to ensure that each device can obtain a reasonable share of bandwidth.

[0107] In step C4, for seamless switching operation, the user manually triggers the switching, or the switching is automatically triggered when certain conditions are met, such as when the priority of the new device exceeds that of the current active device by a certain degree. If there is a problem in the switching process, the system automatically adjusts the switching strategy or performs error recovery operations, such as reallocating resources or rolling back to the previous state.

[0108] The above implementation modes are merely descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary engineering and technical personnel in the field shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A multi-device fast pairing and seamless screen switching system based on ultrasonic signals, characterized in that: include: Ultrasonic processing module, switching module, data transmission module and intelligent control processing module connected by wireless communication, wherein: The ultrasonic processing module is used to generate the sending and receiving of ultrasonic signals through phase modulation technology and adaptive filtering technology, and perform pairing; The switching module is used to switch the screen projection connection after successful pairing; The data transmission module is used to establish a temporary data transmission channel for data transmission; The intelligent control processing module is used to receive screen projection requests through the screen projection system optimization algorithm, time window and priority algorithm, and dynamically adjust the screen projection resource allocation.

2. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 1 is characterized in that: The method of generating the sending and receiving of ultrasonic signals by using phase modulation technology and adaptive filtering technology and performing pairing includes the following steps: A1: The device ID and other information are converted into the original binary information of the binary digital sequence through the cyclic redundancy check algorithm, and error correction coding is performed and redundant information is added; A2: According to the carrier frequency of the ultrasound, different phase states are divided to represent different binary values. For each bit in the binary sequence after error correction coding, the phase of the ultrasound signal is changed according to the binary value. A3: The phase modulated signal is sent out through the ultrasonic transmitter, and the ultrasonic receiver receives the signal and processes the received signal through the recursive least squares algorithm; A4: The filtered signal is subjected to coherent detection with a locally generated reference signal having the same carrier frequency and phase as the transmitting end. The coherent detection process is performed by a multiplier and an integrator. A5: Decode the signal after coherent detection. According to the phase modulation rules, restore the different phase states to corresponding binary values ​​and remove the redundant information added by the error correction coding.

3. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 2 is characterized in that: The method of processing the received signal by a recursive least squares algorithm comprises the following steps: A31: By sampling the received ultrasonic signal, the continuous ultrasonic signal r(t) is converted into a discrete time signal r[n], where n represents the sequence number of the sampling point, the filter coefficient vector ω(0) is a small random vector, and the filter length L and the error covariance matrix P(0) are initialized to a diagonal matrix; A32: At each sampling point n, in the process of calculating the filter output, the formula for the input signal vector is: x(n) = [r[n], r[n-1], ..., r[n-L+1]] T , the filter output formula is: y(n) = ω(n-1) T x(n), where: T represents transpose; A33: In ultrasonic signal processing, if there is a reference signal, the expected signal is the value of the reference signal at the current sampling point; if there is no reference signal, the expected signal is determined based on prior knowledge. Let the expected signal be d(n), the error formula is: e(n) = d(n) - y(n), and the gain vector formula is: Where λ is the forgetting factor, and the formula for updating the filter coefficient is: ω(n)=ω(n-1)+k(n)e(n), The formula for updating the error covariance matrix is: A34: Repeat steps A32 and A33, and continuously update the filter coefficients as the sampling points increase, so that the output of the filter gradually approaches the desired signal.

4. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 2 is characterized in that: The ultrasonic receiver is an ultrasonic transducer that converts ultrasonic signals into electrical signals. The received continuous ultrasonic signals are discretized according to the sampling frequency to obtain a discrete-time signal sequence. The device information obtained by decoding is compared with the locally cached device list. If the decoded device ID exists in the local device list, it is considered to be a legitimate device and a connection operation is performed. During the connection process, a confirmation signal is sent to the access device. After the access device receives and confirms it, the pairing is confirmed to be successful.

5. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 2 is characterized in that: When multiple devices process pairing requests in parallel, a dictionary is created to store the pairing request information of all devices to be paired. According to the multi-threaded parallel computing framework, the collected pairing requests are assigned to different computing units for processing through polling allocation. Each computing unit starts processing the assigned pairing requests at the same time, and records the pairing status of each device according to a two-dimensional table. During the parallel processing, each computing unit updates the pairing status of the corresponding device in the status record table in real time according to the processing results. Devices that have not been successfully paired remain in a waiting state.

6. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 1, characterized in that: The switching screen projection connection after the pairing is successful includes the following steps: B1: When confirming the switch of the screen projection connection, the user triggers the switch request through the operation interface, and the screen projection device automatically determines whether the screen projection needs to be switched according to the preset conditions. For example, when the screen projection device detects that a specific application is started or a specific event occurs, the screen projection switching process is automatically started. The screen projection device selects the appropriate access device according to the current environment and needs; B2: After the second access device confirms that the connection between the current projection device and the first access device is closed, pairing and projection connection are performed through encoding, phase modulation technology, adaptive filtering technology and coherent detection technology; B3: During the switching process, after the second access device and the projection device are paired successfully, a part of the projection content is cached in advance. During the process, after the second access device is paired successfully and before sending a confirmation request for pairing, the content to be projected begins to be cached. When the pairing request is confirmed to be successful, the projection device immediately plays the content from the cache; B4: For single video data, use the smooth transition technology of the video stream to gradually fade in the new projection content and fade out the old projection content when switching; for single audio data, use the cross-fade technology to gradually reduce the volume of the old audio and gradually increase the volume of the new audio.

7. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 1 is characterized in that: During the pairing and connection establishment process, the access device and the projection device negotiate parameters and determine a unified projection resolution, frame rate, audio format, and video format based on the capabilities of both devices and the supported projection parameters. After confirming the pairing, the projection device and the access device encode and compress the content to be projected and send it to the projection device through the established connection channel. The projection device receives and decodes the projection content and then displays and plays it.

8. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 1, characterized in that: Preprocess the successfully paired devices, allocate bandwidth shares to each successfully paired device according to the needs of screen projection and the priority of the device, limit the bandwidth usage of each device through network traffic shaping technology, allocate independent buffer space to each successfully paired device through dynamic memory allocation technology, manage the buffer through a circular buffer data structure, allocate processor time to successfully paired devices through a time slice round-robin scheduling algorithm according to the priority of the device and the complexity of the screen projection task, perform predictive preloading according to the user's behavior patterns and historical records, store the preloaded content through the least recently used algorithm in the cache replacement algorithm, cache the preloaded content in the memory or storage medium of the local device, obtain the hardware status information according to the interface to detect the status of the screen projection hardware, communicate with the developer server of the application and the device manager to detect the status of the screen projection software, take corresponding processing measures if abnormal hardware or software status is detected, and record the results of the device status detection in the log file.

9. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 1, characterized in that: In the process of establishing a temporary data transmission channel for data transmission, the data transmission protocol and wireless communication technology are selected according to the setting selection interface of the screen projection application. The data transmission protocol includes UDP or TCP, and the wireless communication technology includes Wi-Fi Direct, Bluetooth or DLNA. The selection is recorded and used. If the user wants to switch the wireless communication technology or transmission protocol during the screen projection process, a switching request is issued through the setting interface of the application. After receiving the user's switching request, the application suspends the current data transmission and prepares for switching. Encryption is performed through the WPA2 security protocol during the screen projection connection.

10. The multi-device fast pairing and seamless screen switching system based on ultrasonic signals according to claim 1, characterized in that: The method receives the screen projection request through the screen projection system optimization algorithm, time window and priority algorithm, and dynamically adjusts the allocation of screen projection resources; comprises the following steps: C1: The screen projection system continuously listens to screen projection requests from various devices, monitors the status of the active device currently performing screen projection in real time, sets a fixed-length time window, calculates the relationship between the arrival time and the current time window for each new screen projection request, and adjusts the priority according to the position of the request in the time window; C2: According to the priority algorithm, the comprehensive priority of each screen projection request is calculated by weighted summation, and all pending screen projection requests are sorted according to the comprehensive priority. If there are multiple requests with the same highest priority, the next access device is determined based on the first-come-first-served principle or random selection. At the same time, the system records these requests with the same priority. C3: Continuously evaluate the currently available projection resources and dynamically adjust the allocation of projection resources according to the priority and projection requirements. While adjusting the resource allocation, the system prepares for seamless switching, including preloading the projection content of the newly connected device into the buffer and establishing a communication channel with the new device. C4: When the new connected device is ready and the resource allocation adjustment is completed, the system triggers a seamless switching operation. During the switching process, the system gradually transfers the projection output from the current active device to the new connected device. At the same time, the system continues to monitor the performance indicators during the switching process. When a problem occurs, the system automatically adjusts the switching strategy or performs error recovery operations.

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