A wireless screen projection method and system integrating Bluetooth control and power supply management

Abstract

The application relates to the field of Bluetooth communication technology and discloses a wireless screen projection method and system integrating Bluetooth control and power supply management, which comprises the following steps: a sending end device adds a preset time delay to a Bluetooth data packet response according to an energy state of the sending end device; a receiving end device decodes the energy state by measuring the difference between a round-trip response time and a reference value, and performs screen projection strategy adjustment and negotiation in cooperation when a condition is met. The application encodes the energy state into a Bluetooth communication timing sequence, realizes endogenous perception and adaptive adjustment of a power supply state of a screen projection system, fundamentally solves the screen projection interruption problem caused by energy state disconnection in a traditional scheme, ensures smooth and non-perceptual picture quality switching through a bidirectional negotiation mechanism, and significantly improves the reliability and user experience of wireless screen projection.

Description

TECHNICAL FIELD

[0001] The application relates to a wireless projection method and system integrating Bluetooth control and power supply management, and belongs to the technical field of Bluetooth communication. BACKGROUND

[0002] In the field of Bluetooth wireless projection technology, the mainstream existing scheme adopts a one-way instruction driving mode: the receiving end sends control instructions to the sending end, and the sending end continuously transmits video streams at a fixed high quality. This mode implies a fundamental limitation: the energy state of the sending end is regarded as an invisible variable independent of the control system. When a user conducts a business demonstration or long-time viewing, the system has no awareness of the power decay, resulting in a sudden interruption of the projection when the power is exhausted, and forming a destructive cliff collapse experience.

[0003] Although the industry tries to optimize coding and decoding to reduce power consumption, it cannot solve the core contradiction between the control link and the energy state. In particular, in a complex electromagnetic environment (such as a conference room scene with multiple Wi-Fi devices concurrent), channel jitter is easy to be confused with energy state signals, causing misgrading decisions. At the same time, the existing technology has a blind area in recognizing user intentions, which makes it unable to distinguish between key content and ordinary content, resulting in compromised experience in low-power high-priority scenarios.

[0004] Specifically, the existing technology mainly has three deep bottlenecks: 1. The projection system cannot perceive the power decay trend and loses the ability to actively adjust; 2. Channel jitter and energy delay signals are difficult to distinguish, leading to misjudgment; 3. The content value dimension is missing, making the degradation strategy deviate from the real demand. Therefore, how to realize accurate decision-making with energy perception and adaptive adjustment driven by user intentions under complex working conditions, and completely avoid unexpected interruption of projection services, has become a technical problem to be solved by the present application. SUMMARY

[0005] The application provides a wireless projection method and system integrating Bluetooth control and power supply management, which mainly aims to solve the service interruption risk caused by the invisibility of the energy state in the Bluetooth projection system, and the problem of inaccurate control decisions and disconnection of user intentions in complex environments.

[0006] To achieve the above purpose, the application provides a wireless projection method integrating Bluetooth control and power supply management, which comprises the following steps:

[0007] Step 1: The sending end device obtains its own battery power, and determines the current energy state level according to the battery power, wherein the energy state level includes at least two preset discrete levels; the sending end device adds a corresponding preset time delay to the Bluetooth data packet in response to the receiving end device, according to the energy state level, to encode the energy state level into the timing of Bluetooth communication;

[0008] Step 2, the receiving end device measures the round-trip response time of the Bluetooth data packet, and decodes the energy state level of the sending end device according to the time delay difference between the round-trip response time and a preset reference round-trip time;

[0009] Step 3, when the decoded energy state level meets the preset condition, the receiving end device sends a control message containing a projection strategy adjustment proposal to the sending end device, the projection strategy adjustment proposal including at least one of reducing the video stream resolution, reducing the video stream frame rate, and changing the video stream encoding code rate;

[0010] Step 4, the sending end device receives the control message and responds to the projection strategy adjustment proposal according to its own situation, and the receiving end device cooperates with the sending end device to execute the projection strategy adjustment after receiving the confirmation response of the sending end device.

[0011] Preferably, the energy state level includes a first energy state level, a second energy state level, a third energy state level, and a fourth energy state level, and the corresponding relationship between the additional time delay value attached by the sending end device in response to the Bluetooth data packet and the energy state level is as follows: the preset additional time delay value corresponding to the first energy state level is ; the preset additional time delay value corresponding to the second energy state level is ; the preset additional time delay value corresponding to the third energy state level is ; and the preset additional time delay value corresponding to the fourth energy state level is .

[0012] Preferably, the first energy state level corresponds to the battery level of the sending end device being greater than 70%, the second energy state level corresponds to the battery level of the sending end device being between 30% and 70%, the third energy state level corresponds to the battery level of the sending end device being between 10% and 30%, and the fourth energy state level corresponds to the battery level of the sending end device being less than 10%.

[0013] Preferably, the preset reference round-trip time is determined by measuring the round-trip response time of multiple Bluetooth data packets and performing averaging processing at the beginning of the projection session establishment when the sending end device is in a high energy state; the sending end device determines whether to send a confirmation response to the receiving end device based on its real-time charging state and whether there is a charger connected.

[0014] Preferably, after the receiving end device decodes the energy state level of the sending end device, and before the receiving end device sends the control message containing the projection policy adjustment proposal to the sending end device, the following steps are further included: when the time delay difference between the round-trip response time and the preset reference round-trip time falls within the preset jitter ambiguity interval, the receiving end device sends a time stamp packet for challenge to the sending end device; after receiving the time stamp packet for challenge, the sending end device immediately encapsulates its own receiving time stamp in a time stamp response packet and returns to the receiving end device, and the sending end device does not add any preset time delay related to the energy state when processing the time stamp packet for challenge; the receiving end device calculates the pure physical round-trip time of the current channel according to the time stamp response packet and the local time stamp when the time stamp response packet is received; and the receiving end device reconfirms the energy state level of the sending end device according to the difference between the round-trip response time and the pure physical round-trip time.

[0015] Preferably, the sending end device determines the corresponding preset time delay according to the current content priority provided by the application program running thereon in combination with the energy state level, wherein the content priority includes at least one of critical content, ordinary content, and background content; the receiving end device learns the energy state level and the content priority of the sending end device by decoding the corresponding preset time delay; and the projection policy adjustment proposal sent by the receiving end device to the sending end device is determined based on the energy state level and the content priority.

[0016] Preferably, when determining the corresponding preset time delay, the sending end device looks up according to the combination of the energy state level and the content priority in a preset two-dimensional encoding matrix to determine a unique corresponding preset time delay value.

[0017] Preferably, when the receiving end device decodes that the sending end device is in a low energy state level and the content priority is critical content, the projection policy adjustment proposal is a proposal to maintain the current high-quality projection or only to perform lossless compression.

[0018] Preferably, the steps of cooperatively performing the projection policy adjustment include: the receiving end device includes the expected projection time extension according to the policy adjustment in the proposal when sending the projection policy adjustment proposal; the sending end device dynamically adjusts its video stream transmission parameters to match the new projection policy after confirming acceptance of the proposal, including but not limited to reducing the bit rate of video encoding or using a more efficient codec; and the receiving end device synchronously adjusts its video decoding and display parameters to seamlessly adapt to the change of the transmission parameters of the sending end device.

[0019] A wireless projection system integrating Bluetooth control and power supply management, the system comprising:

[0020] The sending terminal device is configured with: an energy state sensing module, configured to acquire the battery power of the sending terminal device and determine the current energy state level to which it belongs, wherein the energy state level comprises at least two preset discrete levels; a time delay coding module, configured to attach a corresponding preset time delay to the Bluetooth data packet in response to the receiving terminal device according to the energy state level, so as to encode the energy state level into the timing of Bluetooth communication; and a response processing module, configured to receive the control message sent by the receiving terminal device and respond to the screen projection strategy adjustment proposal according to the situation of the sending terminal device.

[0021] The receiving terminal device is configured with: a round-trip time measurement module, configured to measure the round-trip response time of the Bluetooth data packet; a time delay decoding module, configured to decode the energy state level of the sending terminal device according to the time delay difference between the round-trip response time and a preset reference round-trip time; a strategy negotiation module, configured to send a control message containing a screen projection strategy adjustment proposal to the sending terminal device when the decoded energy state level meets the preset condition, wherein the screen projection strategy adjustment proposal comprises at least one of reducing the video stream resolution, reducing the video stream frame rate and changing the video stream encoding rate; and a cooperative execution module, configured to cooperatively execute the screen projection strategy adjustment with the sending terminal device after receiving the confirmation response of the sending terminal device.

[0022] Compared with the prior art, the present application has the following advantages:

[0023] 1. By converting the sending terminal battery state into a micro disturbance of the Bluetooth communication timing, the energy information can be integrated into the control link in real time without an independent transmission channel; the receiving terminal synchronously senses the energy state transition by analyzing the difference between the timing change and the preset reference; this mechanism upgrades the Bluetooth communication timing from a simple data carrier to an energy state transmission medium, while maintaining protocol compatibility, so that the screen projection system first has the endogenous sensing ability of the energy state, thereby avoiding the screen projection interruption risk caused by the energy state disconnection in the traditional scheme.

[0024] 2. When the energy state change is sensed, the receiving terminal actively initiates a negotiation proposal containing specific degradation parameters, the sending terminal responds to the confirmation in combination with the charging state and the application scenario, and both parties synchronously adjust the encoding and decoding strategy based on the negotiation result, so that the picture quality switching process is smooth and imperceptible; this paradigm transition from one-way instruction to two-way negotiation converts the forced interruption at the energy critical point into a controllable service quality transition, ensuring the continuity of core tasks in high-value scenarios such as business demonstrations; and the closed-loop verification logic of introducing time stamp interrogation packets and instant response is introduced, the difference between the reference round-trip time and the pure channel time delay is compared, and the interference of physical jitter on the energy time delay signal is accurately stripped; this mechanism gives the system the ability to distinguish between active time delay coding and passive channel fluctuation in complex electromagnetic environments, so that the energy state judgment still maintains decision reliability in extreme working conditions such as Wi-Fi co-frequency interference, significantly improving the robust boundary of the main scheme.

[0025] 3, the sending end encodes the application layer content priority (key / ordinary / background) and the energy state in two dimensions, synchronously transmits the physical state and the user intention through a single time sequence disturbance signal; the receiving end generates a scene degradation strategy according to this, such as maintaining lossless picture quality in a low power high priority scene; this cross-layer information fusion mechanism enables the system to upgrade from an electricity-driven mechanical response to a value-driven intelligent decision, realizing the essential unity of technical optimization and user experience. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The preset response delay matrix diagram of the energy level and the content priority joint mapping of the application;

[0027] Figure 2 The preset additional time delay and the energy state level and the content priority relationship diagram of the application;

[0028] Figure 3 The time stamp challenge mechanism and the high-quality screen projection strategy cooperative switching flow timing diagram of the application;

[0029] Figure 4 The comparison diagram of the application of the identification accuracy rate of the challenge mechanism under different channel jitter intensities.

[0030] The purpose of the application, the function characteristics and the advantages will be further explained in combination with the embodiments, with reference to the drawings. DETAILED DESCRIPTION

[0031] It should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0032] The embodiment of the application provides a wireless screen projection method integrating Bluetooth control and power supply management, and the method comprises the following steps:

[0033] Step 1, the sending end device acquires the battery power of itself, and determines the current energy state level according to the battery power, wherein the energy state level comprises at least two preset discrete levels; the sending end device adds a corresponding preset time delay to the response of the receiving end device according to the energy state level, so as to encode the energy state level into the time sequence of the Bluetooth communication;

[0034] Step 2, the receiving end device measures the round-trip response time of the Bluetooth data packet, and decodes the energy state level of the sending end device according to the time delay difference between the round-trip response time and a preset reference round-trip time;

[0035] Step 3, when the decoded energy state level meets the preset condition, the receiving end device sends a control message containing a projection screen strategy adjustment proposal to the sending end device, the projection screen strategy adjustment proposal including at least one of reducing the video stream resolution, reducing the video stream frame rate, and changing the video stream encoding code rate;

[0036] Step 4, the sending end device receives the control message and responds to the projection screen strategy adjustment proposal according to its own situation, and the receiving end device cooperates with the sending end device to execute the projection screen strategy adjustment after receiving the confirmation response of the sending end device.

[0037] Preferably, the energy state level includes a first energy state level, a second energy state level, a third energy state level, and a fourth energy state level, and the corresponding relationship between the time delay attached by the sending end device in response to the Bluetooth data packet and the energy state level is as follows: the preset additional time delay value corresponding to the first energy state level is ; the preset additional time delay value corresponding to the second energy state level is ; the preset additional time delay value corresponding to the third energy state level is ; and the preset additional time delay value corresponding to the fourth energy state level is .

[0038] Preferably, the first energy state level corresponds to the battery power of the sending end device being greater than 70%, the second energy state level corresponds to the battery power of the sending end device being between 30% and 70%, the third energy state level corresponds to the battery power of the sending end device being between 10% and 30%, and the fourth energy state level corresponds to the battery power of the sending end device being less than 10%.

[0039] Preferably, the preset reference round-trip time is determined by measuring the round-trip response time of multiple Bluetooth data packets and performing average processing on them at the beginning of the projection screen session establishment when the sending end device is in a high energy state; the sending end device determines whether to send a confirmation response to the receiving end device based on its real-time charging state and whether there is a charger connected.

[0040] Preferably, after the receiving end device decodes the energy state level of the sending end device, and before the receiving end device sends the control message containing the projection policy adjustment proposal to the sending end device, the following steps are further included: when the time delay difference between the round-trip response time and the preset reference round-trip time falls within the preset jitter ambiguity interval, the receiving end device sends a time stamp packet for challenge to the sending end device; after receiving the time stamp packet for challenge, the sending end device immediately encapsulates its own receiving time stamp in a time stamp response packet and returns to the receiving end device, and the sending end device does not add any preset time delay related to the energy state when processing the time stamp packet for challenge; the receiving end device calculates the pure physical round-trip time of the current channel according to the time stamp response packet and the local time stamp when the time stamp response packet is received; and the receiving end device reconfirms the energy state level of the sending end device according to the difference between the round-trip response time and the pure physical round-trip time.

[0041] Preferably, the sending end device determines the corresponding preset time delay according to the current content priority provided by the application program running thereon in combination with the energy state level, wherein the content priority includes at least one of critical content, ordinary content, and background content; the receiving end device learns the energy state level and the content priority of the sending end device by decoding the corresponding preset time delay; and the projection policy adjustment proposal sent by the receiving end device to the sending end device is determined based on the energy state level and the content priority.

[0042] Preferably, when determining the corresponding preset time delay, the sending end device looks up according to the combination of the energy state level and the content priority in a preset two-dimensional encoding matrix to determine a unique corresponding preset time delay value.

[0043] Preferably, when the receiving end device decodes that the sending end device is in a low energy state level and the content priority is critical content, the projection policy adjustment proposal is a proposal to maintain the current high-quality projection or only to perform lossless compression.

[0044] Preferably, the steps of cooperatively performing the projection policy adjustment include: the receiving end device includes the expected projection time extension according to the policy adjustment in the proposal when sending the projection policy adjustment proposal; the sending end device dynamically adjusts its video stream transmission parameters to match the new projection policy after confirming acceptance of the proposal, including but not limited to reducing the bit rate of video encoding or using a more efficient codec; and the receiving end device synchronously adjusts its video decoding and display parameters to seamlessly adapt to the change of the transmission parameters of the sending end device.

[0045] A wireless projection system integrating Bluetooth control and power supply management, the system comprising:

[0046] The sending terminal device is configured with: an energy state sensing module for acquiring the battery power of the sending terminal device itself and determining the current energy state level to which it belongs, wherein the energy state level comprises at least two preset discrete levels; a time delay coding module for adding a corresponding preset time delay to the Bluetooth data packet in response to the receiving terminal device according to the energy state level, so as to encode the energy state level into the timing of Bluetooth communication; and a response processing module for receiving the control message sent by the receiving terminal device and responding to the screen projection strategy adjustment proposal according to its own situation;

[0047] The receiving terminal device is configured with: a round-trip time measurement module for measuring the round-trip response time of the Bluetooth data packet; a time delay decoding module for decoding the energy state level of the sending terminal device according to the time delay difference between the round-trip response time and a preset reference round-trip time; a strategy negotiation module for sending a control message containing a screen projection strategy adjustment proposal to the sending terminal device when the decoded energy state level meets the preset condition, the screen projection strategy adjustment proposal comprising at least one of reducing the video stream resolution, reducing the video stream frame rate, and changing the video stream encoding rate; and a cooperative execution module for cooperatively executing the screen projection strategy adjustment with the sending terminal device after receiving the confirmation response of the sending terminal device. It should be noted that the screen projection strategy adjustment mechanism proposed in the present application is not mandatory automatic execution, but is based on real-time state sensing of the sending terminal device and cooperative judgment of the receiving terminal device, and makes a comprehensive decision in combination with whether it is currently in a charging state, content priority, and user configuration strategy. For example, in system design, the sending terminal device is allowed to actively ignore part of the degradation suggestion in the case of detecting the access of an external charger, so as to maintain a high-quality screen projection experience. At the same time, the application layer configuration is also supported to enable the user to independently set whether to enable the dynamic adjustment function driven by the energy state, so as to guarantee service continuity while retaining user control over picture quality performance, which all belong to the extension implementation mode known to those skilled in the art.

[0048] Embodiment 1: In this embodiment, the sending terminal device first acquires the battery power of itself, determines the current energy state level to which it belongs according to the power value, and the energy state level is divided into four preset discrete levels in a specific implementation, corresponding to the four intervals of battery power greater than 70%, between 30% and 70%, between 10% and 30%, and less than 10%. For each energy state level, the system presets a corresponding additional response time delay value, respectively denoted as 、 、 and The additional delay is superimposed on the normal response delay when the sending end device responds to the receiving end Bluetooth data packet, and constitutes the timing of the coded signal embedded in the Bluetooth communication; the receiving end device measures the round-trip response time of the data packet, compares it with the reference round-trip time obtained by multiple measurements and average processing at the beginning of the session (i.e. when the sending end is in a high energy state), decodes the corresponding preset additional delay value from the difference between the two, and further identifies the current energy state level of the sending end. In view of the channel jitter caused by electromagnetic interference in the actual Bluetooth communication environment, which may interfere with the above-mentioned delay decoding result, the application further designs and introduces a set of time stamp challenge and response mechanism. When the receiving end judges that the difference between the current round-trip delay and the reference time falls within the preset fuzzy jitter interval, making it difficult to identify the energy state level, the receiving end will send a time stamp packet to the sending end for challenge. After receiving the challenge request, the sending end immediately encapsulates the received time stamp to generate a time stamp response packet and returns it, and does not add any additional delay related to the energy state in the response process. The receiving end calculates the pure physical round-trip time of the current channel according to the local time stamp of the received response packet and the sending end time stamp carried by it, and further strips the non-coding delay component caused by channel disturbance, to achieve more accurate identification of the energy state level. When the decoded energy state level meets the specific screen projection strategy adjustment condition, the receiving end will actively send a control message containing adjustment proposal to the sending end. The control message can contain suggestions to adjust at least one of the video stream resolution, frame rate and encoding code rate. After receiving the control message, the sending end will judge whether to respond to the adjustment proposal in combination with the current charging state and the content priority indicated by the running application program, and complete the parameter adjustment with the receiving end after confirming acceptance.

[0049] To support the above-mentioned screen projection policy adjustment mechanism assisted by content priority, the sending end considers the energy state level and the priority of the current content when setting the additional response delay, which can include predefined categories such as key content, ordinary content, and background content in the system. The sending end determines a unique additional response delay value by looking up the preset two-dimensional encoding matrix according to the combination relationship of the energy state level and the content priority, and completes the encoding of the two-dimensional state information accordingly. The receiving end can obtain the energy state level and the content priority of the sending end synchronously while decoding the response delay, so as to generate more accurate policy adjustment suggestions according to the scene information composed of the two, for example, in the scenario of low power and key content priority, the system can choose to maintain the current high-quality screen projection state or only perform lossless compression to ensure that the display quality of core information is not affected. At the same time, in order to ensure that the policy adjustment process has good controllability and execution consistency, the receiving end can also attach a projected screen delay adjustment amount in its control message, and the sending end adjusts the video encoding parameters dynamically according to the prompt information, including but not limited to reducing the video encoding bit rate or replacing the more efficient codec, etc. At the same time, the receiving end synchronously adjusts its video decoding and display parameters, so as to keep the parameters coordinated with the sending end, and ensure the play continuity and picture consistency of the video stream in the adjustment process.

[0050] In a complete screen projection session initialization phase, the sending end device obtains the current battery power through the battery state acquisition module, and classifies the energy state according to the power value. Specifically, the power value greater than 70% is set as the first energy level, 30-70% is set as the second energy level, 10-30% is set as the third energy level, and less than 10% is set as the fourth energy level. The system presets a corresponding additional response delay value for each level, which will be added to the normal response delay when the sending end device responds to the Bluetooth data packet sent by the receiving end, to embed state information in the communication timing. The setting of this additional delay value fully considers the actual physical response characteristics of the Bluetooth link, ensuring that the delay difference between levels is sufficient to be effectively distinguished by the receiving end device under stable channel conditions, and will not trigger the communication retry mechanism of the Bluetooth link layer.

[0051] In response to the current energy state level, the response delay coding module introduces a preset additional response delay in the response when receiving the receiving end data packet, realizes the coding transmission of the energy state information to the link layer, in order to guarantee the availability of the system under the Bluetooth link fluctuation or external interference scene, the setting of the delay value considers the communication stability and the distinguishability, usually should satisfy that the additional response delay difference between at least two energy levels is more than twice the average link delay jitter, ensures that the system has the discrimination robustness in the actual deployment environment; in order to improve the judgment accuracy of the energy state decoding, especially when there is physical channel fluctuation influence, the embodiment further introduces a group of time stamp challenge and response mechanism, the receiving end equipment detects that the difference between the round trip response delay of the current data packet and the reference average value counted in the initialization stage falls into the set fuzzy interval, the interval should be determined according to the typical fluctuation range of the Bluetooth physical layer, and a time stamp challenge packet for confirmation is sent to the sending end equipment, the sending end equipment generates a time stamp response packet and returns immediately after receiving the challenge request, and at the same time, it is ensured that no additional response delay is introduced in the response process, the receiving end calculates the physical link round trip time by comparing the local recorded receiving time with the sending time stamp carried in the response packet, thereby stripping the influence of the physical layer link uncertain factor on the judgment result from the overall delay, and realizing the accurate recovery of the energy state level.

[0052] After the energy state level is effectively decoded, the receiving end will enter the screen projection strategy decision stage. In order to realize the strategy judgment with more context awareness ability, the sending end device extracts the type information of the current screen projection content in each communication response period by applying the content recognition module. The content information is identified and classified according to the media content metadata provided by the application program running in the device. Typical classification includes key content, ordinary content and background content. The system takes the content priority information and the current energy state level as inputs together to find the preset two-dimensional response delay coding matrix to determine the unique additional delay value for this round of response. When the receiving end decodes the delay, it can synchronously obtain the current energy state and content priority of the sending end device, thereby providing accurate context information support for the subsequent control strategy generation. Based on the decoding result, the receiving end device generates a control message including screen projection parameter adjustment suggestions through the control message generation module. The specific suggestions include reducing video resolution, reducing video frame rate, adjusting video encoding rate or switching to a more efficient encoding and decoding algorithm, etc. For the combination scene of key content and low energy state level, the system can choose to maintain high-quality screen projection state or use lossless compression strategy to ensure information integrity. In the control message, the receiving end can also attach the predicted screen projection time delay change amount as a reference benchmark for subsequent bilateral video parameter synchronization adjustment. After receiving the control message, the sending end device will respond to the processing module in combination with the current charging state and content priority information. If the current is not connected to an external power supply, the system will prefer to use the parameter optimization method suggested in the control message, such as switching the original encoding method from H.264 to HEVC, adjusting the frame rate from thirty frames per second to twenty frames per second, or reducing the video resolution to HD level, etc. The adjustment will take effect at the key frame refresh point in the current encoding group, and feedback adjustment confirmation information through the Bluetooth link. After receiving the adjustment confirmation information, the receiving end device will switch to the corresponding video parameter configuration through the video decoding scheduling module, and update the decoding strategy synchronously from the next key frame, ensuring that the entire video stream maintains continuous playback during the parameter change process, avoiding abnormal phenomena such as stuttering or screen tearing.

[0053] Example 3: This example is carried out in a test platform simulating a typical application scenario, aiming to illustrate the specific operation process, parameter setting basis and technical effect of the present application in an interference environment; the test platform is composed of a notebook computer as a sending end device and a wireless projection receiver as a receiving end device, both of which have Bluetooth communication function; in order to simulate the complex electromagnetic environment that may be encountered in real use, the test is carried out under the condition that multiple Wi-Fi networks and other Bluetooth devices are working concurrently; in the initial stage of the projection session establishment, in order to establish a stable and reliable baseline round-trip time, the sending end device needs to be in a high energy state, for example, when the battery power is sufficient and the external power is turned on, under this condition, by measuring the round-trip response time of multiple Bluetooth data packets from the receiving end device to the sending end device and receiving the acknowledgement response of the sending end device, and by averaging a series of time values measured, a baseline round-trip time can be determined, which is the zero reference point for all subsequent time delay decoding operations, and its reasonable setting is the basis for the accuracy of energy state judgment, for example, a baseline value obtained under certain test conditions can be 4.8 milliseconds; on this basis, the present embodiment further illustrates the two-dimensional coding mechanism of energy state level and additional time delay, the core of this mechanism is to construct a two-dimensional coding matrix, the setting of this matrix needs to achieve a technical balance between the timeliness of state change perception and the stability of Bluetooth link communication, if the additional time delay value is too small, it is difficult to distinguish from noise in the presence of channel jitter, which may lead to energy state misjudgment; on the contrary, if the time delay value is too large, it may exceed the normal response range allowed by the Bluetooth protocol, causing unnecessary communication retry, therefore, the additional time delay value can be set as a non- arithmetic sequence, a larger time delay increment is used when the energy state level is lower, to achieve clearer state differentiation. See Table 1: Preset additional response time delay coding table corresponding to energy state level and content priority.

[0054]

[0055] In a continuous projection application, the sending end device is powered by a battery, and its power changes from high to low, when its battery power drops to 25%, it enters the third energy state level, and the current projection content is a presentation identified by the application program as key content, the time delay coding module of the sending end device will add a preset time delay of 10 milliseconds to the response to the receiving end data packet according to the foregoing matrix, the round-trip time measured by the round-trip time measurement module of the receiving end device is about 10 milliseconds after deducting the baseline value of 4.8 milliseconds, and the time delay decoding module can decode the current combined state of the sending end device as the third energy state level and key content accordingly.

[0056] Considering the impact of channel jitter on delay measurement in practical applications, this invention introduces a timestamp challenge mechanism. When the delay difference measured by the receiver falls within a preset jitter ambiguity range—for example, if the value is between two encoded delay values—causing ambiguity in state determination, the challenge mechanism can be initiated. The receiver sends a timestamp packet for challenge to the transmitter. Upon receiving the timestamp packet, the transmitter immediately encapsulates its own received timestamp in a timestamp response packet and returns it without adding any preset delay related to energy state. The receiver can then calculate the current pure physical round-trip time by comparing its local time with the timestamp in the response packet. Subtracting this pure physical round-trip time from the total round-trip response time removes channel jitter interference, resulting in a more accurate additional delay value actively encoded by the transmitter, thereby achieving precise confirmation of the transmitter's energy state level. After effectively decoding the transmitter's state, the system enters the negotiation and adjustment phase of the projection strategy, based on the aforementioned third energy state level and key content scenario. For example, the strategy negotiation module of the receiving device can generate a screen projection strategy adjustment proposal containing specific parameters. For instance, it may suggest adjusting the video stream resolution from 1080p to 720p, maintaining the frame rate at 30fps to ensure the clarity of key content, and appropriately reducing the video encoding bitrate. This control message is received by the sending end via the Bluetooth link. The response processing module of the sending device, considering its current status of not being connected to a charger, confirms the proposal and indicates the video frame position where the parameter adjustment will take effect in its response information. Subsequently, at the next key frame refresh point of video encoding, the sending end begins to use the new video stream transmission parameters. After receiving the confirmation information, the collaborative execution module of the receiving end also synchronously adjusts its decoding and display parameters to ensure a seamless switch when the next key frame arrives. This achieves a smooth transition in the user's visual perception, avoiding abnormal phenomena such as black screen, stuttering, or screen tearing. This collaborative process effectively extends the remaining battery power available for screen projection while ensuring the continuity of core tasks.

[0057] Example 4: This example combines Figures 1 to 4 This paper describes the implementation of a wireless screen projection method and system that integrates Bluetooth control and power management. Figure 1 As shown, the energy levels listed vertically on the left include Level 1 (>70%), Level 2 (30%~70%), Level 3 (10%~30%), and Level 4 (<10%). The horizontal columns above list the priorities of three categories: critical content, general content, and background content. Within the intersecting cells of the matrix, the preset additional response latency values ​​for the corresponding combinations are displayed, with the specific values ​​indicated in parentheses, in milliseconds (ms). , , , , , , , , and ,in to These represent the baseline additional response delay values ​​at four discrete energy state levels. Furthermore, exemplary coding points are highlighted in the figure using dashed circles and arrows. The system further explains the corresponding system status through example scene annotation boxes, namely, power: 25%, content: key content, encoding delay: 10ms. It clearly shows the positioning logic and preset response delay configuration of this specific status combination in the two-dimensional encoding matrix, thereby realizing the system's synchronous perception and linkage response to energy status level and user intent (reflected by content priority).

[0058] like Figure 2 As shown, the horizontal axis represents the energy status levels, including Level 1 (>70%), Level 2 (30%~70%), Level 3 (10%~30%), and Level 4 (<10%). The vertical axis represents the preset additional delay (milliseconds), which is used to encode the above status information in Bluetooth communication by adding a response delay. The figure contains three curves, each corresponding to a different content priority. The solid curve and the dots marked in the legend represent key content, the dashed curve and the square mark represent ordinary content, and the dotted-dash curve and the diamond mark represent background content. As the energy status level changes from high to low, the preset additional delay (milliseconds) shows a significant upward trend in all three content priorities. Especially in the Level 4 (<10%) critical state, all types of content are set with a higher additional delay to enhance the distinguishability of the status signal.

[0059] like Figure 3 As shown, the process begins with the receiving device responding to a Bluetooth data packet. After measuring the round-trip time (RTT) and finding it falls within the jitter ambiguity range, it triggers the transmission of a timestamp packet for a challenge. Upon receiving this challenge request, the sending device immediately returns a response without additional delay as a timestamp response packet. The receiving device accurately calculates the pure physical round-trip time based on the response packet, thus completing channel interference removal and confirming the sending device's combined state as: Fourth Energy State Level and Key Content. Subsequently, the receiving device sends a control message containing a proposal to maintain high quality. The sending device's response processing module, based on its own state, accepts the proposal. The sending device further sends an acknowledgment response, indicating the effective video frame position. At the next key frame refresh point in the video encoding, it executes the transmission of the video stream encoded with the new parameters, marking that the sending device has switched to the new parameters. Simultaneously, the receiving device synchronously switches its decoding parameters for seamless playback, achieving a smooth transition to the high-quality projection strategy. And as... Figure 4As shown, the accuracy of the system in identifying the energy state under different channel jitter intensities is shown, the solid line represents the accuracy without using the time stamp challenge mechanism, and the dotted line represents the accuracy after using the time stamp challenge mechanism. The results show that the time stamp challenge mechanism significantly improves the identification accuracy in a high jitter environment, from 60% to more than 95%.

[0060] In a high-density conference scenario, there are multiple wireless local area network access points and multiple Bluetooth devices running simultaneously, the system needs to dynamically adapt to the changes in the battery power of the sending device while ensuring the integrity of the video content transmission. In this scenario, the sending device is a portable terminal with Bluetooth communication capability, its current battery power is 45%, the running application is a multimedia presentation tool, and the played content is identified as a key content type. The sending device obtains the current battery power reading through its internal battery state perception module, and maps the power to the second energy state level accordingly. At the same time, the content identification module analyzes the metadata fields provided in the application layer interface, including media type, current window focus state, and user operation behavior parameters, to identify that the current played content belongs to the key content category. After completing the above identification, the sending device finds a preset two-dimensional response delay coding matrix, which takes energy state level as row index and content priority level as column index. Each cell in the matrix corresponds to a unique additional response delay value. The coding matrix is preset in the system initialization stage, and its generation principle is based on the known link jitter tolerance characteristics and the technical constraints of the Bluetooth protocol layer on delay tolerance. It is constructed by engineering modeling, which includes the following design basis: the setting of additional response delay value needs to establish an engineering acceptable balance between state discrimination clarity and communication stability. If the delay difference between adjacent levels is too small, it may increase the uncertainty of state decoding results under channel noise fluctuation conditions. If the difference is set too large, it may interfere with the normal control of the response time limit by the protocol layer, causing communication layer retransmission or connection interruption. Therefore, each additional response delay value in the matrix needs to meet the following conditions: in any two adjacent energy state levels, the additional delay difference under the same content priority should be greater than twice the link jitter range to enhance decoding robustness; in the same energy state level, the additional delay values corresponding to different content priorities should be at least one millisecond apart to ensure the decoding resolution of content priority differentiation; the maximum additional response delay in the overall matrix should be in the safe interval below the maximum tolerable response delay threshold defined by the Bluetooth protocol.

[0061] In this example, since the current state combination is the second energy state level and the key content priority, the corresponding additional response delay value is six milliseconds, which is inserted by the link layer delay control module of the sending end in the response packet generation process, forming a control delay with coding significance within the response time window; after receiving the response packet, the receiving end device calculates the total round-trip response time of the packet through its round-trip time measurement module, and deducts the previously established baseline round-trip time from the response time, which is the statistical average value obtained by the sending end through multiple interactive sampling at the first energy state level in the initialization stage, for example, four point eight milliseconds, thus obtaining the net response delay of six milliseconds, which is used by the receiving end to determine that the current state combination is the second energy state level and the key content priority according to the reverse lookup of the value in the stored coding matrix; at the same time, in order to improve the stability and fault tolerance of the judgment, the system sets a fuzzy jitter interval, the upper and lower limits of which are determined by the statistical data of the historical round-trip delay of the link, and are automatically updated according to the dynamic fluctuation in the running process, for example, the current fuzzy interval is set to plus or minus one point five milliseconds, if the measured net response delay falls into the overlapping interval corresponding to two legal additional delay values, the judgment result is not effective, the receiving end starts the time stamp query process for confirmation, specifically, the receiving end sends a data packet containing the local sending time stamp field, the sending end adds the receiving time stamp field immediately after receiving and returns, without introducing additional response delay, the receiving end calculates the pure physical round-trip time based on the two time stamp fields in the response packet, thereby obtaining a reference delay that is not affected by coding disturbance, which is further used to assist the verification of the previous coding judgment result, if the deviation is found to be beyond the tolerance range, the original state judgment is corrected, otherwise it remains unchanged.

[0062] After the state recognition is completed, the policy negotiation module of the receiving end generates a set of proposed adjustments of the screen projection parameters to be discussed based on the current identified second energy state level and the key content category, in combination with the system operation policy generation module. The proposed adjustments include the following adjustment items: the current video resolution is adjusted from full high definition standard to seven hundred twenty line high definition format, the frame rate is maintained at thirty frames per second, and the encoding code rate is reduced by about twenty percent. The generation of the adjustment strategy takes the following technical factors into consideration: under the premise of ensuring the visual quality of the key content, the parameter adjustment is performed without changing the encoder type, which can effectively reduce the system resource consumption and computational burden, and avoid additional energy consumption pressure. The optimization idea is based on the hardware support capability of existing mainstream devices for specific encoding standards, and the screen projection parameter change is completed without causing an increase in processing delay; after receiving the parameter adjustment proposal, the sending end judges based on the local running state judgment result (currently in the unconnected power state) by the response processing module, and confirms that the above adjustment scheme is acceptable under the current conditions. Under the premise that the response conditions are met, the sending end notifies the receiving end that the adjustment scheme is adopted through the confirmation response information, and specifies that the parameter change will take effect at the next key frame refresh point. Subsequently, the sending end updates the encoder configuration parameters before the next key frame is generated, so that the subsequent key frames are encoded and sent in the newly set format. At the same time, after receiving the confirmation response, the receiving end updates the related parameter configuration of the decoding module to ensure smooth synchronization at the key frame switching, and to protect the picture coherence and content consistency from being affected. Thus, in the scene where the Bluetooth communication link condition is complex and the power continues to change, the embodiment realizes the state coding recognition and strategy dynamic adjustment process based on the cooperation of both ends, taking into account the user experience and resource optimization goals, and has good implementation feasibility and deployment adaptability in typical engineering environments.

[0063] In one intelligent conference interaction scene involving multiple Bluetooth devices running concurrently and dynamic channel state changes, the sending end device is a portable tablet terminal with Bluetooth communication capability, and the receiving end device is a wireless receiving module with image decoding and display functions. In this scene, the sending end device determines its energy state level and content priority category according to its internal battery power state and the type of application program being run. The energy state level is divided into four preset levels according to the device battery power, corresponding to power greater than 70%, between 30% and 70%, between 10% and 30%, and less than 10%. The content priority is divided into key content, ordinary content, and background content according to the attributes of the media content being presented.

[0064] In the embodiment, to further enhance the distinguishability of the additional response delay and the signal recognition stability, the sending terminal device obtains the corresponding additional response delay value by searching the system preset two-dimensional coding matrix according to the combination of the current energy state level and the content priority, the construction of the matrix refers to the typical delay jitter amplitude distribution characteristics of the Bluetooth communication link, and the minimum difference between adjacent delay values is set to be greater than twice the standard deviation of the link jitter, so as to avoid the superimposed error of the response delay falling into the fuzzy interval, and at the same time, in the design of the matrix, it is ensured that the delay values of different rows in any column satisfy the discrimination redundancy, and the delay values corresponding to different columns in any row also have distinguishability, so as to ensure that whether the content priority changes or the energy state level changes, it can be uniquely mapped and recognized by the additional response delay; the sending terminal device introduces the additional response delay into the response process when responding to the Bluetooth data packet of the receiving terminal device, the delay is realized by the delay control mechanism of the lower layer of the Bluetooth protocol stack in the system, and the time slot structure defined by the Bluetooth protocol is not modified, but the response trigger time is delayed by software, to ensure that the addition of the delay does not trigger the communication protocol retransmission mechanism, the maximum value of the additional response delay is always within the maximum time limit of the Bluetooth link layer confirmation response, to avoid affecting the stability of the link establishment and data interaction. After receiving the response packet, the receiving terminal device records the current round-trip response time through the local time measurement module, and calculates the difference value based on the reference response time established in the initialization stage, the reference response time is obtained by continuously measuring and averaging multiple times in the projection session initialization stage when the sending terminal device has sufficient power and the system is stable, in the embodiment, when the difference value falls within the discrimination interval range set by the system, the receiving terminal device reversely inquires the energy state level and the content priority of the sending terminal according to the known coding matrix; if the calculated response delay difference value is located in the overlapping area between two possible coding delays, or the receiving terminal device detects that the historical response time of the current system link has a significant fluctuation trend, the receiving terminal device immediately enters the challenge confirmation process, which triggers the timestamp response behavior of the sending terminal device by sending a specific challenge timestamp packet, the sending terminal device records the receiving timestamp and encapsulates it into the response data packet returned to the receiving terminal device after receiving the challenge timestamp packet, and does not introduce any additional response delay in the process, the receiving terminal device compares the local sending timestamp with the received returning timestamp, calculates the pure physical round-trip time of the link, and deducts the physical round-trip time from the measured total response delay, to finally obtain the additional response delay component introduced by the sending terminal active coding, thereby the receiving terminal can perform secondary confirmation on the identification of the energy state level and the content priority, and improve the identification robustness of the system in the electromagnetic interference environment.

[0065] On the basis of stable identification results, if the receiving end judges that the sending end is currently in a lower energy state level and the content priority is not in the critical category, the receiving end will construct a control message containing the projection strategy adjustment parameters, including but not limited to the adjustment suggestions of video resolution, frame rate and encoding code rate. The control message can also carry an expected video response delay adjustment value, which is used to prompt the sending end to adjust the synchronization rhythm of the video stream during the parameter switching process. The sending end, after receiving the control message, combines whether it is currently in a charging state and the identification results of the registered application programs in the operating system for the current content type to decide whether to accept the strategy adjustment, and identifies the key frame position of the adjustment in the response. The sending end then starts the encoding parameter update operation at the specified key frame point. The parameter adjustment will be completed before the generation of the new key frame in the current encoding group. The updated content includes the resolution setting, the upper limit of the code rate, and the possible encoding algorithm type (such as switching from H.264 to HEVC). At the same time, after receiving the confirmation response, the receiving end also synchronously modifies the decoder parameter configuration, and updates the decoding parameters at the upcoming key frame to ensure smooth and continuous video streaming.

[0066] It is obvious to those skilled in the art that the present application is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application.

Claims

1. A wireless screen projection method integrating Bluetooth control and power supply management, characterized in that, The method comprises the following steps: Step 1, the sending terminal device acquires its own battery power, and determines the current energy state level according to the battery power, wherein the energy state level comprises at least two preset discrete levels; the sending terminal device adds a corresponding preset time delay to the response Bluetooth data packet of the receiving terminal device according to the energy state level, so as to encode the energy state level into the timing of the Bluetooth communication; Step 2, the receiving terminal device measures the round-trip response time of the Bluetooth data packet, and decodes the energy state level of the sending terminal device according to the time delay difference between the round-trip response time and a preset reference round-trip time; Step 3, when the decoded energy state level meets the preset condition, the receiving terminal device sends a control message containing a projection screen strategy adjustment proposal to the sending terminal device, and the projection screen strategy adjustment proposal comprises at least one of reducing the video stream resolution, reducing the video stream frame rate and changing the video stream encoding rate; Step 4, the sending terminal device receives the control message and responds to the projection screen strategy adjustment proposal according to its own situation, and the receiving terminal device cooperates with the sending terminal device to execute the projection screen strategy adjustment after receiving the confirmation response of the sending terminal device.

2. The wireless screen projection method of claim 1, wherein, The energy state levels include a first energy state level, a second energy state level, a third energy state level and a fourth energy state level, and the corresponding relationship between the time delay appended by the sending terminal device in response to the Bluetooth data packet and the energy state level is as follows: the preset appended time delay value corresponding to the first energy state level is ; The preset additional time delay value corresponding to the second energy state level is ; The preset additional time delay value corresponding to the third energy state level is ; The preset additional time delay value corresponding to the fourth energy state level is . 3.The wireless screen projection method of claim 2, wherein, The first energy state level corresponds to the battery power of the sending terminal device greater than 70%, the second energy state level corresponds to the battery power of the sending terminal device between 30% and 70%, the third energy state level corresponds to the battery power of the sending terminal device between 10% and 30%, and the fourth energy state level corresponds to the battery power of the sending terminal device less than 10%.

4. The wireless screen projection method of claim 1, wherein, The preset reference round-trip time is determined by measuring the round-trip response time of the Bluetooth data packet multiple times and averaging the round-trip response time at the beginning of the projection screen session establishment when the sending terminal device is in a high energy state; the sending terminal device determines whether to send a confirmation response to the receiving terminal device based on its real-time charging state and whether there is a charger connected.

5. The wireless screen projection method of claim 1, wherein, After the receiving terminal device decodes the energy state level of the sending terminal device, and before the receiving terminal device sends a control message containing a projection screen strategy adjustment proposal to the sending terminal device, the following steps are further included: when the time delay difference between the round-trip response time and the preset reference round-trip time falls within a preset jitter blur interval, the receiving terminal device sends a timestamp packet for challenge to the sending terminal device; the sending terminal device immediately encapsulates the receiving timestamp of itself in a timestamp response packet and returns to the receiving terminal device after receiving the timestamp packet for challenge; the sending terminal device does not add any preset time delay related to the energy state when processing the timestamp packet for challenge; the receiving terminal device calculates the pure physical round-trip time of the current channel according to the timestamp response packet and the local timestamp when the timestamp response packet is received; the receiving terminal device confirms the energy state level of the sending terminal device again according to the difference between the round-trip response time and the pure physical round-trip time.

6. The wireless screen projection method of claim 1, wherein: The sending terminal device determines a corresponding preset time delay according to a current content priority provided by an application program running thereon and an energy state level, wherein the content priority comprises at least one of critical content, normal content and background content; the receiving terminal device learns the energy state level and the content priority of the sending terminal device by decoding the corresponding preset time delay; and the receiving terminal device sends a control message containing a projection screen strategy adjustment proposal to the sending terminal device, and the projection screen strategy adjustment proposal is determined based on the energy state level and the content priority.

7. The wireless screen projection method of claim 6, wherein, The sending terminal device determines a corresponding preset time delay according to a combination of the energy state level and the content priority, and looks up a preset two-dimensional encoding matrix to determine a unique corresponding preset time delay value.

8. The wireless screen projection method of claim 6, wherein, When the receiving terminal device decodes that the sending terminal device is in a low energy state level and the content priority is critical content, the projection screen strategy adjustment proposal is a proposal to maintain the current high-quality projection screen or only perform lossless compression.

9. The wireless screen projection method of claim 1, wherein, The steps of cooperatively performing the projection screen strategy adjustment include that the receiving terminal device sends a projection screen time extension amount expected according to the strategy adjustment in the proposal when sending the projection screen strategy adjustment proposal; and the sending terminal device dynamically adjusts its video stream transmission parameters to match the new projection screen strategy after confirming acceptance of the proposal, including but not limited to reducing the bit rate of video encoding or using a more efficient codec; and the receiving terminal device synchronously adjusts its video decoding and display parameters to seamlessly adapt to the change of the transmission parameters of the sending terminal device.

10. A wireless projection system integrating Bluetooth control and power management, characterized in that, The system comprises: The sending terminal device is configured with an energy state awareness module for obtaining the battery power of the sending terminal device itself and determining the current energy state level to which it belongs, wherein the energy state level comprises at least two preset discrete levels; a time delay encoding module for appending a corresponding preset time delay to a Bluetooth data packet in response to the receiving terminal device according to the energy state level, so as to encode the energy state level into the timing of Bluetooth communication; and a response processing module for receiving a control message sent by the receiving terminal device and responding to the projection screen strategy adjustment proposal according to its own situation; The receiving terminal device is configured with a round-trip time measurement module for measuring the round-trip response time of the Bluetooth data packet; a time delay decoding module for decoding the energy state level of the sending terminal device according to the time delay difference between the round-trip response time and a preset reference round-trip time; a strategy negotiation module for sending a control message containing a projection screen strategy adjustment proposal to the sending terminal device when the decoded energy state level meets a preset condition, wherein the projection screen strategy adjustment proposal comprises at least one of reducing the video stream resolution, reducing the video stream frame rate and changing the video stream encoding rate; and a cooperative execution module for cooperatively executing the projection screen strategy adjustment with the sending terminal device after receiving the confirmation response of the sending terminal device.

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