Short-distance multi-screen interaction system and multi-screen interaction method based on pure UWB

Abstract

The invention relates to the technical field of short-distance multi-screen interaction, in particular to a short-distance multi-screen interaction system and method based on pure UWB. According to the technical scheme, the system comprises at least two terminal devices communicating through pure UWB, each terminal device comprises a device discovery module, a topology construction module, a video fragmentation module, a pulse modulation module, a space routing module, a multi-screen synchronization module and a hardware configuration module, and detailed description is conducted on all the parts. The method has the advantages that equipment discovery is safe and reliable, topology construction is accurate and dynamic, video transmission is intelligent and efficient, multi-screen synchronization nanosecond-level precision is achieved, the anti-interference capacity is high, routing expansion is convenient and fast, and hardware is low in power consumption and high in performance; in particular, deep fusion of positioning and interaction, creative utilization of multipath signals, full-automatic adaptive experience and low-cost networking expansion are realized, the system is suitable for scenes such as home entertainment and conference cooperation, and reliability, synchronism and user experience of multi-screen interaction are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of short-distance multi-screen interaction, and in particular to a short-distance multi-screen interaction system based on pure UWB and a multi-screen interaction method. BACKGROUND

[0002] Short-distance multi-screen interaction technology is widely used in intelligent office, home entertainment, augmented reality (AR) and other scenarios, and its core requirement is to realize low-latency, high-precision data transmission and synchronization between multiple devices. The current mainstream solution is based on traditional wireless communication technologies such as WiFi and Bluetooth, and realizes device interconnection by building a local area network. For example, in a conference room scenario, a projector and a mobile phone realize screen mirroring through WiFi direct connection, or realize touch signal feedback through Bluetooth protocol.

[0003] Short-distance multi-screen interaction technology needs to meet multiple stringent requirements such as real-time transmission of high-definition video (bandwidth ≥ 10 Gbps, latency ≤ 10 ms), accurate spatial position sensing (positioning error ≤ 5 cm), stable communication in complex environments (BER ≤ 10 -6 -1), and low-complexity system design. However, the current mainstream WiFi, Bluetooth and other traditional wireless technologies have an irreconcilable performance bottleneck: the OFDM modulation technology they rely on has a significantly increased error rate in multipath non-line-of-sight (NLOS) environments, and is affected by channel competition in the public frequency band, so the actual transmission rate is often less than 50% of the theoretical value (e.g. WiFi 5 multi-device sharing rate < 500 Mbps), which cannot meet the 4K video transmission requirement; Bluetooth AOA positioning technology is limited by signal wavelength and antenna size, with a positioning error ≥ 30 cm, making it difficult to achieve millimeter-level interaction; and the "UWB+WiFi" hybrid solution attempts to integrate technical advantages, but the deployment of multiple protocol stacks increases hardware costs by more than 30%, and the protocol conversion process introduces ≥ 10 ms of additional latency, significantly increasing system complexity and power consumption.

[0004] In the prior art, how to simultaneously realize high rate, high precision, strong anti-interference capability and low complexity design under a single communication architecture has become a core technical problem restricting the development of short-distance multi-screen interaction technology. Therefore, we propose a short-distance multi-screen interaction system based on pure UWB and a multi-screen interaction method. SUMMARY

[0005] The purpose of the present application is to propose a short-distance multi-screen interaction system based on pure UWB and a multi-screen interaction method to solve the problems in the background art.

[0006] In a first aspect, the present application provides a short-distance multi-screen interaction system based on pure UWB, including at least two terminal devices communicating through pure UWB, each terminal device including the following modules and hardware configurations:

[0007] A device discovery module is configured to implement mutual discovery between devices based on an IEEE 802.15.4z protocol;

[0008] A topology construction module is configured to construct a topology between devices based on an IEEE 802.15.4z HRP mode, and implement topology construction with a precision of 10 cm, and trigger path prediction based on Kalman filtering when the device moving speed is greater than 1 m / s;

[0009] A video slicing module is configured to slice a video;

[0010] A pulse modulation module is configured to map an H.265 intra-frame prediction mode to a UWB pulse position offset, wherein Δτ=2ns / bit, a 3-pulse redundant encoding is used for an I frame macro block, and a single-pulse differential encoding is used for a P frame;

[0011] A spatial routing module is configured to perform spatial routing selection according to the constructed topology;

[0012] A multi-screen synchronization module is configured to implement synchronized display between multiple screens;

[0013] A hardware configuration module includes a master control chip, an antenna array, and a communication protocol support unit.

[0014] Optionally, the master control chip in the hardware configuration module supports an AOA (Angle of Arrival) algorithm and a ToF (Time of Flight) algorithm, integrates a 6.5 GHz center frequency UWB radio frequency front end, supports an IEEE 802.15.4z protocol HRP mode with a pulse repetition frequency PRF≥64 MHz, has a built-in 128 KB SRAM for storing a Kalman filtering state matrix for topology construction, and has a hardware-accelerated path loss calculation unit for real-time calculation of a non-line-of-sight propagation path loss PL (dB)=45+20lg(d), wherein PL represents the path loss, d represents a communication distance, 45 represents a constant term representing an initial path loss, and 20 represents a path loss exponent.

[0015] Optionally, the antenna array in the hardware configuration module is a 4×4 MIMO-UWB antenna, adopts a planar inverted F antenna (PIFA) structure, a single antenna unit has a bandwidth≥500 MHz, a beamforming algorithm is based on a minimum variance distortionless response (MVDR) criterion, a signal gain≥12dBi is achieved within a beam width of ±15° through a digital beam synthesizer, a distance between adjacent antenna units is λ / 2, and λ is a center frequency corresponding wavelength.

[0016] Optionally, the device discovery module adopts a CSMA / CA contention slot mechanism in the device registration stage, specifically: the initial value of the backoff window is 16 slots, each slot is 2μs wide, when detecting that the channel is busy, randomly select 0-2 n -1 slots for backoff, where n is the number of backoff times and n≤4; the registration signaling contains device type identification (main screen / sub screen), antenna array calibration parameters and supported maximum transmission unit (MTU≥1500 bytes).

[0017] Optionally, the video transmission stage of the pulse modulation module includes a dynamic subcarrier allocation module, which adopts an optimal matching strategy based on the Hungarian algorithm to divide 52 subcarriers into 32 data subcarriers and 20 pilot subcarriers, with a subcarrier interval of 4MHz, supporting orthogonal frequency division multiplexing (OFDM) modulation, and each subcarrier symbol period is 250ns; wherein the pilot subcarriers are used for real-time channel estimation, and the data subcarriers adopt 16-QAM or 64-QAM modulation mode.

[0018] Optionally, in the H.265 frame mapping mechanism of the pulse modulation module, the 3-pulse redundant encoding of the I-frame macroblock adopts time diversity technology, with a pulse interval of Δτ=2ns, each pulse carries 4bit position information, and the single-pulse differential encoding of the P-frame is based on the prediction residual of the previous frame macroblock. When the residual threshold is ≥128, the differential encoding with a pulse position offset Δτ=4ns is triggered, and the encoding efficiency is ≥0.8bit / pulse.

[0019] Optionally, the spatial routing module includes a topology database and a dynamic routing table; the topology database stores the real-time distance (accuracy ≤10cm), signal strength (RSSI) and number of multipath components between devices; the dynamic routing table adopts a shortest path first algorithm based on link quality (LQ-SPF), and when the link quality indicator (LQI) is <80 or the device moving speed is >1m / s, the routing table is updated, and the update period is ≤100ms.

[0020] Optionally, the multi-screen synchronization module adopts a distributed synchronization mechanism based on timestamps, with a synchronization beacon interval of 1ms, containing a 64bit timestamp and a device ID, and the maximum ratio combining technology of the RAKE receiver is used to eliminate the multipath delay difference, with a synchronization error of ≤2ns, supporting master-slave synchronization mode, with the main screen as the time master node and the sub screen as the slave node.

[0021] In a second aspect, the application provides a pure UWB-based short-distance multi-screen interaction method, applied to the pure UWB-based short-distance multi-screen interaction system of the first aspect, including the following steps:

[0022] Device discovery: mutual discovery between devices is realized by the device discovery module based on the IEEE 802.15.4z protocol;

[0023] Topology construction: the topology construction module is used to construct the topology structure between devices based on the HRP mode of IEEE 802.15.4z, and the topology construction with a precision of 10 cm is realized, and when the device moving speed is greater than 1 m / s, the path prediction based on Kalman filtering is triggered;

[0024] Video slicing: the video is sliced by the video slicing module;

[0025] Pulse modulation: the pulse modulation module is used to map the H.265 intra prediction mode to the UWB pulse position offset, wherein Δτ = 2 ns / bit, 3-pulse redundant encoding is used for I frame macroblocks, and single-pulse differential encoding is used for P frames;

[0026] Spatial routing: the spatial routing module is used to select the spatial routing according to the constructed topology structure;

[0027] Multi-screen synchronization: the multi-screen synchronization module is used to realize the synchronous display between multiple screens.

[0028] Optionally, in the topology construction process, when the device moving speed is greater than 1 m / s, the Kalman filtering path prediction is triggered, and specifically includes:

[0029] ①The position coordinates (x t-2 ,y t-2 ,z t-2 ), (x t-1 ,y t-1 ,z t-1 ), (x t ,y t ,z t ) of the previous three time points are used to calculate the velocity vector (v x ,v y ,vz) and the acceleration vector (a x ,a y ,az);

[0030] ②Establish a state space model: the state vector X t =[x t ,v xt ,y t ,v yt ,z t ,vz t ] T , and the state transition matrix is:

[0031]

[0032] Wherein, Δt is the sampling period = 10 ms, (x t ,y t ,z t) is the position coordinate of the device in three-dimensional space at time t, (v xt ,v yt , vz t ) is the velocity component of the device in x, y, z axis direction at time t;

[0033] III. Obtain the measurement value by measuring equation Z t = HX t + V t , wherein H is an observation matrix, V t is Gaussian noise, and the covariance matrix R = diag ([0.01, 0.01, 0.01]);

[0034] IV. Perform prediction update and observation update, and output the predicted position (x t+1 | t , y t+1 | t , z t+1 | t ) at the next time, and the prediction error is ≤3cm.

[0035] Compared with the prior art, the present application has the following beneficial technical effects:

[0036] The CSMA / CA mechanism reduces channel conflict, AES-128 encryption and Diffie-Hellman key exchange ensure communication security, 10cm-level positioning accuracy is realized based on IEEE 802.15.4z, and Kalman filtering is used for real-time tracking of high-speed mobile devices.

[0037] The adaptive fragmentation strategy matches the video complexity, I-frame redundant encoding and P-frame differential encoding improve transmission efficiency and reliability, timestamp + RAKE receiver realizes ≤2ns synchronization error, and master-slave mode ensures that multiple screens are completely consistent.

[0038] DS-UWB spread spectrum technology and 4x4 MIMO antenna beamforming adapt to complex electromagnetic environments, LQ-SPF algorithm dynamically updates the route, uses existing devices as relay nodes to expand the communication range, and does not require additional hardware. Chip set UWB radio frequency front end, hardware acceleration path loss calculation and Kalman filtering, reduce power consumption.

[0039] The short-range multi-screen interaction system and method based on pure UWB have the advantages of safe and reliable device discovery, accurate and dynamic topology construction, intelligent and efficient video transmission, nanosecond-level precision of multi-screen synchronization, strong anti-interference ability, convenient routing expansion and low-power high-performance hardware, especially realizing the deep integration of positioning and interaction, creative use of multipath signals, full-automatic adaptive experience and low-cost networking expansion, and are suitable for home entertainment, conference collaboration and other scenes, and significantly improve the reliability, synchronization and user experience of multi-screen interaction. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 This is a block diagram illustrating the principle of a short-range multi-screen interactive system based on pure UWB. Detailed Implementation

[0041] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0042] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0043] Example 1

[0044] This embodiment provides a short-range multi-screen interactive system based on pure UWB, such as... Figure 1 As shown, it includes at least two terminal devices that communicate via pure UWB. Each terminal device includes a device discovery module, a topology building module, a video segmentation module, a pulse modulation module, a spatial routing module, a multi-screen synchronization module, and a hardware configuration module. Each part is described in detail below.

[0045] In this embodiment, the device discovery module is used to realize mutual discovery between devices based on the IEEE 802.15.4z protocol. During the device registration phase, the device discovery module adopts a CSMA / CA contention time slot mechanism, specifically: the initial backoff window value is 16 time slots, each time slot width is 2μs, and when a busy channel is detected, slots 0-2 are randomly selected. n -1 time slot is used for backoff, where n is the number of backoffs and n≤4; the registration signaling includes the device type identifier (master screen / sub-screen), antenna array calibration parameters, and the maximum supported transmission unit (MTU≥1500 bytes). The CSMA / CA mechanism reduces channel contention and ensures communication reliability during the device discovery phase; the clear device type identifier facilitates subsequent master / slave role allocation, and the MTU parameter supports large-size data transmission, improving system compatibility.

[0046] The topology building module is used to build the topology between devices based on the IEEE 802.15.4z HRP mode, achieving topology building with an accuracy of 10cm. When the device moving speed is >1m / s, path prediction based on Kalman filtering is triggered. High-precision topology building supports accurate perception of device spatial position. Kalman filtering adapts to dynamic moving scenarios, improves the system's real-time tracking capability of device movement, and ensures the spatial synchronization of multi-screen interaction.

[0047] The video slicing module is used for slicing the video; the slicing can reduce the amount of single frame data, adapt to the bandwidth limitation of short distance communication, and improve the transmission efficiency; and the receiving end is facilitated to segment and recombine, and the influence of network congestion is reduced.

[0048] In the embodiment, the pulse modulation module is used for mapping the H.265 intra prediction mode to the UWB pulse position offset, wherein Δτ=2 ns / bit, 3-pulse redundancy coding is used for I frame macroblocks, and single pulse differential coding is used for P frames; the video transmission stage of the pulse modulation module comprises a dynamic subcarrier allocation module, 52 subcarriers are divided into 32 data subcarriers and 20 pilot subcarriers by using the optimal matching strategy based on the Hungarian algorithm, the subcarrier interval is 4 MHz, orthogonal frequency division multiplexing (OFDM) modulation is supported, and the symbol period of each subcarrier is 250 ns; the pilot subcarriers are used for real-time channel estimation, and the data subcarriers adopt 16-QAM or 64-QAM modulation mode. In the H.265 frame mapping mechanism of the pulse modulation module, the 3-pulse redundancy coding of the I frame macroblock adopts time diversity technology, the pulse interval is Δτ=2 ns, each pulse carries 4-bit position information, the single pulse differential coding of the P frame is based on the prediction residual of the previous frame macroblock, the residual threshold is greater than or equal to 128, the differential coding of the pulse position offset Δτ=4 ns is triggered, and the coding efficiency is greater than or equal to 0.8 bit / pulse. The redundancy coding (I frame) and the differential coding (P frame) are combined, the reliability and the transmission efficiency are considered, and the interframe difference characteristics of the video stream are adapted; the dynamic subcarrier allocation and the OFDM modulation improve the spectrum utilization, the pilot assisted channel estimation enhances the anti-multipath interference capability, and the 16-QAM / 64-QAM modulation supports high-speed data transmission.

[0049] Further, the spatial routing module is used for spatial routing selection according to the constructed topology structure; the spatial routing module comprises a topology database and a dynamic routing table; the topology database stores the real-time distance (accuracy ≤10 cm), signal strength (RSSI) and number of multipath components between devices; the dynamic routing table adopts a shortest path first algorithm based on link quality (LQ-SPF), when the link quality index (LQI) is less than 80 or the device moving speed is greater than 1 m / s, the routing table is updated, and the update period is less than or equal to 100 ms. The topology database stores the link state in real time, and provides accurate basis for routing selection; the LQ-SPF algorithm combines the link quality to dynamically adjust the route, adapts to the device movement and channel change, and reduces the transmission delay and the packet loss rate.

[0050] It is worth mentioning that the multi-screen synchronization module is used to realize the synchronous display between multiple screens, the multi-screen synchronization module adopts a timestamp-based distributed synchronization mechanism, the synchronization beacon interval is 1ms, contains 64bit timestamp and device ID, the maximum ratio combining technology of RAKE receiver is used to eliminate multipath delay difference, the synchronization error is less than or equal to 2ns, the master-slave synchronization mode is supported, the main screen is the time master node, and the sub-screen is the slave node. The nanosecond-level synchronization accuracy ensures that the multi-screen display picture is completely consistent, and the user experience is improved;

[0051] The RAKE receiver suppresses multipath interference, the master-slave mode simplifies synchronization management, and the system robustness is enhanced.

[0052] In the embodiment, the hardware configuration module includes a master control chip, an antenna array and a communication protocol support unit. The master control chip in the hardware configuration module supports AOA (Angle of Arrival) algorithm and ToF (Time of Flight) algorithm, integrates a UWB radio frequency front end with a center frequency of 6.5GHz, supports HRP mode of IEEE 802.15.4z protocol, the pulse repetition frequency PRF is greater than or equal to 64MHz, 128KB SRAM is built-in for storing Kalman filter state matrix for topology construction, and a hardware-accelerated path loss calculation unit is provided for real-time calculation of non-line-of-sight propagation path loss PL (dB) = 45 + 20lg (d), wherein PL represents path loss, d represents communication distance, 45 represents a constant term representing initial path loss, and 20 represents a path loss exponent. The AOA (Angle of Arrival) algorithm refers to a positioning technology for determining the position of a signal source by measuring the direction (angle) of the signal arriving at the receiver. This technology is widely used in wireless communication, radar, indoor positioning (such as Bluetooth or UWB positioning), etc. fields, and the angle estimation is realized through multi-antenna array or phase difference calculation; the ToF algorithm refers to a positioning technology for calculating distance or position by measuring the propagation time of a signal from a transmitting end to a receiving end. Its principle is based on the formula: distance = propagation time x light speed, and high-precision ranging is realized by accurately measuring the time difference. This technology is widely used in LiDAR (Laser Radar), UWB (Ultra-Wideband) positioning, indoor navigation, unmanned aerial vehicle obstacle avoidance, autonomous driving, etc. fields.

[0053] The antenna array in the hardware configuration module is a 4x4 MIMO-UWB antenna, adopts a planar inverted-F antenna (PIFA) structure, the bandwidth of a single antenna unit is ≥500MHz, the beamforming algorithm is based on a minimum variance distortionless response (MVDR) criterion, the signal gain in a beam width of ±15° is achieved through a digital beam synthesizer, the signal gain is ≥12dBi, the spacing between adjacent antenna units is λ / 2, and λ is the wavelength corresponding to the center frequency. The special UWB chip has high integration, supports high-precision positioning and high-speed communication, and the hardware acceleration function reduces the computing power consumption; the MIMO antenna combined with the beamforming technology improves the signal gain and the anti-interference ability, expands the communication coverage, and optimizes the spatial signal transmission quality.

[0054] In the embodiment, the IEEE 802.15.4z protocol is used to achieve a topology construction precision of 10 cm, Kalman filtering is used to dynamically track a mobile device (a speed greater than 1 m / s triggers prediction), a CSMA / CA mechanism and an AES-128 encryption are used to ensure the safety of device discovery and communication, an adaptive fragmentation strategy (1024 KB / 512 KB / 256 KB) is used to match the video complexity and reduce the latency, an I frame 3-pulse redundancy coding is combined with a P frame differential coding and an OFDM modulation (52 subcarriers) to balance the transmission efficiency and the error code resistance (an error code rate is less than or equal to 10 -6 ). Based on a timestamp and a RAKE receiver, a multipath suppression technology is used to achieve a synchronization error of less than or equal to 2 ns, ensure that multiple screens have completely consistent pictures, and simplify system management in a master-slave mode. DS-UWB spread spectrum technology (processing gain 23 dB) and 4x4 MIMO antenna beamforming (gain ≥12dBi) are used to improve the signal stability in a complex environment and support non-line-of-sight (NLOS) propagation path loss calculation. Dynamic routing and low-cost expansion: LQ-SPF algorithm is used to update the routing table in real time, and existing devices are used as relay nodes (LQI is optimal and the power is greater than or equal to 30%), so that the communication range can be expanded without additional hardware.

[0055] It is worth noting that the 10 cm level positioning accuracy of UWB is not only used for topology construction, but also supports spatial perception interaction between multiple screens (such as dynamically adjusting the display layout according to the device position), breaks through the limitation of traditional multiple screens only “picture synchronization”, and realizes immersive space interaction. The multipath signal that is considered as interference in traditional communication is converted into a synchronization advantage through a RAKE receiver, and the multipath component is used to improve the time delay estimation accuracy, and the synchronization error is still less than or equal to 2 ns in a non-line-of-sight environment, which is better than traditional wireless technologies.

[0056] Hardware-level low-power optimization: built-in hardware acceleration units (such as path loss calculation, Kalman filter state storage) reduce power consumption while achieving high performance, adapting to the long-term running needs of mobile devices. Dynamic fragmentation, relay selection, and other mechanisms run automatically, and users do not need to manually configure them. The system adjusts parameters in real time based on content complexity, device movement state, and channel quality, and the technical details are completely transparent. By using existing sub-screen node relay forwarding (forwarding gain ≥ 10 dB, time delay ≤ 50 ns), the multi-screen system coverage can be expanded at almost zero cost, especially suitable for flexible networking in scattered scenarios such as homes and conference rooms.

[0057] Embodiment 2

[0058] A short-range multi-screen interaction method based on pure UWB is applied to the short-range multi-screen interaction system based on pure UWB described in Embodiment 1, and includes the following steps:

[0059] Device discovery: Through the device discovery module, mutual discovery between devices is realized based on the IEEE 802.15.4z protocol; the following steps are specifically performed:

[0060] The terminal device listens to the beacon frame on the default channel (center frequency 6.5 GHz) for a duration of ≥ 50 ms; after detecting the beacon frame, a request frame (RTS) containing device capability information is sent, the RTS frame format includes an 8-bit device type field, a 16-bit antenna calibration parameter field, and a 16-bit MTU field; after receiving the response frame (CTS), identity authentication is completed through a four-way handshake, the authentication process uses the AES-128 encryption algorithm, and the key negotiation is based on the Diffie-Hellman key exchange protocol. The standardized beacon listening and handshake mechanism ensures the compatibility and reliability of device discovery; the AES-128 encryption and Diffie-Hellman key exchange ensure the security of the communication link, preventing data eavesdropping and forgery.

[0061] Topology construction: The topology construction module is used to construct the topology structure between devices based on the HRP mode of IEEE 802.15.4z, achieving 10 cm precision topology construction, and triggering path prediction based on Kalman filtering when the device moving speed > 1 m / s; during the topology construction process, Kalman filter path prediction is triggered when the device moving speed > 1 m / s, specifically including:

[0062] ①Using the position coordinates (x t-2 ,y t-2 ,z t-2 ), (x t-1 ,y t-1 ,z t-1 ), and (x t ,y t ,z t) calculate the velocity vector (v x ,v y ,vz) and the acceleration vector (a x ,a y ,az);

[0063] ② Establish state space model: state vector X t =[x t ,v xt ,y t ,v yt ,z t ,vz t ] T , state transition matrix:

[0064]

[0065] Where, Δt is the sampling period = 10ms, (x t ,y t ,z t ) is the position coordinates of the device in three-dimensional space at time t, (v xt ,v yt ,vz t ) is the velocity component of the device in x, y, z axis direction at time t;

[0066] ③ Obtain the measurement value through the measurement equation Z t =HX t +V t , wherein H is the observation matrix, V t is Gaussian noise, and the covariance matrix R = diag ([0.01, 0.01, 0.01]);

[0067] ④ Perform prediction update and observation update, output the predicted position (x t+1 | t ,y t+1 | t ,z t+1 | t ) at the next time, and the prediction error is ≤3cm. The dynamic prediction model based on historical trajectory effectively tracks the high-speed moving device and reduces the positioning delay; the three-dimensional space state estimation improves the real-time performance of the topological structure and adapts to the dynamic layout change of the device in multi-screen interaction.

[0068] In the pulse modulation process, the DS-UWB spread spectrum code uses a 31-bit Gold sequence, the chip rate is 500MHz, the processing gain PG = 10lg(500MHz / 20Mbps) = 23dB, and the spread spectrum signal bandwidth ≥500MHz; the receiver realizes despreading through a matching filter and a sliding correlator, and when the power of the co-frequency interference signal is ≤-20dBm, the bit error rate BER is ≤10 -6The dynamic prediction model based on historical trajectory effectively tracks high-speed moving devices and reduces positioning delay; three-dimensional space state estimation improves the real-time performance of the topology structure and adapts to the dynamic layout changes of the devices in multi-screen interaction. The spread spectrum technology enhances the anti-narrowband interference capability, the processing gain improves the signal reliability, and is suitable for short-distance complex electromagnetic environment; the low bit error rate ensures the accuracy of video data transmission and reduces the retransmission overhead.

[0069] Video slicing: the video is sliced by a video slicing module; the video slicing module adopts a content-based adaptive slicing strategy, specifically: the H.265 encoded video stream is divided by GOP (group of pictures), each GOP contains one I frame and ≤15 P / B frames; the complexity index of each GOP is calculated (based on the macroblock type distribution and the motion vector density), and when the complexity ≥ threshold T1, the slice size is set to 1024KB; when the complexity < T1 and ≥ T2, the slice size is set to 512KB; when the complexity < T2, the slice size is set to 256KB; 128bit timestamp and 32bit slice sequence number are added at the head of each slice, which is used for receiving end recombination and time delay compensation. The content adaptive slicing optimizes the transmission efficiency, the high complexity segment adopts large slice to reduce the slicing overhead, and the low complexity segment adopts small slice to reduce the time delay; the timestamp and sequence number assist the receiving end to accurately recombine the data and compensate the transmission time delay, ensuring continuous playing of the video stream.

[0070] Pulse modulation: the H.265 intra prediction mode is mapped to the UWB pulse position offset by a pulse modulation module, where Δτ = 2ns / bit, the I frame macroblock adopts 3-pulse redundant encoding, and the P frame adopts single-pulse differential encoding;

[0071] Spatial routing: the spatial routing module is used for spatial routing selection according to the constructed topology structure; in the spatial routing selection process, when it is detected that there are ≥3 sub-screen links in the multi-screen topology, a relay selection algorithm is started, and the specific steps are: calculating the link quality parameters (LQI = RSSI + SNR - path loss) of each potential relay node; selecting the node with the maximum LQI value and the remaining power ≥30% as the relay; establishing a two-hop route of source node→relay node→target node, the relay node amplifies and forwards the pulse signal, the forwarding gain ≥10dB, and the time delay ≤50ns. The relay node expands the communication coverage range and solves the connection problem of long-distance devices in the multi-screen system; the relay selection strategy based on the link quality and node state balances the transmission efficiency and node energy consumption, and improves the overall stability of the system.

[0072] Multi-screen synchronization: the multi-screen synchronization module is used to realize the synchronous display between multiple screens. In the multi-screen synchronization step, the master screen sends a synchronization beacon frame every 1 ms, and the beacon frame contains a 64-bit global timestamp (based on the device internal crystal oscillator, accuracy ±1ppm) and a synchronization sequence number; after the slave screen receives the beacon frame, the following operations are performed: the correlator group of the RAKE receiver performs time delay estimation on the multipath signal to obtain the time stamp t rx of the earliest arrival path (EA path) rx ; calculate the transmission delay Δt=(t tx -t tx ) / 2 (assuming symmetric two-way transmission); adjust the local clock phase so that the slave screen clock is deviated from the master screen clock by ≤2ns; perform clock frequency calibration every 100ms, and the calibration algorithm is based on the crystal oscillator frequency drift compensation model. The nanosecond-level phase calibration ensures real-time synchronization, and the microsecond-level frequency calibration suppresses long-term clock drift; the RAKE receiver uses the multipath signal to improve the time delay estimation accuracy, and the master-slave synchronization architecture reduces the system complexity, which is suitable for large-scale multi-screen networking.

[0073] In the application, the CSMA / CA mechanism is used to reduce channel conflict, and the AES-128 encryption and Diffie-Hellman key exchange are combined to ensure the reliability and security of device discovery and authentication. Based on the IEEE 802.15.4z HRP mode, 10cm-level positioning accuracy is realized, and Kalman filtering is used to track high-speed moving devices (speed>1m / s triggers prediction) in real time, which is suitable for dynamic scenes. The content adaptive fragmentation strategy (1024KB / 512KB / 256KB) matches the video complexity, reduces the delay and overhead; I-frame redundant encoding, P-frame differential encoding and OFDM modulation balance transmission efficiency and reliability. Based on the timestamp and RAKE receiver multipath suppression, a synchronization error of ≤2ns is realized to ensure that the multiple screen pictures are completely consistent, and the master-slave mode simplifies system management. DS-UWB spread spectrum technology (processing gain 23dB, bit error rate ≤10 -6 ) and 4x4 MIMO antenna beamforming (gain≥12dBi) improve signal stability and coverage range in complex environments. The LQ-SPF algorithm dynamically updates the routing table, and the relay selection mechanism uses existing devices to expand the communication range without additional hardware, reducing the cost.

[0074] It is worth mentioning that the high-precision positioning (10cm level) of UWB is not only used for topology construction, but also can support spatial perception interaction between multiple screens, such as dynamically adjusting the display content layout or interaction logic according to the physical location of the device, and enhancing the immersive experience. In traditional communication, multipath interference is often regarded as a challenge, but through the multipath combining technology of the RAKE receiver, the system instead uses multipath signals to improve the precision of time delay estimation and the stability of synchronization, and performs better in non-line-of-sight (NLOS) environment. The hardware acceleration function (such as path loss calculation) of the chip and the signal gain of the MIMO antenna are combined to realize high-performance communication while reducing power consumption, which is suitable for long-time running of mobile devices.

[0075] The mechanisms such as dynamic fragmentation, encoding strategy and relay selection do not require user intervention, and the system automatically adjusts the parameters according to the content characteristics and environmental changes. The user only needs to focus on the interaction itself, and the technical details are transparent. The relay node uses existing devices (sub-screens) to realize signal forwarding, without the need to deploy dedicated relay devices, and expands the coverage range at a very low cost when networking multiple devices, which is suitable for decentralized scenarios such as homes and conference rooms.

[0076] The above specific embodiments are only several optional embodiments of the present application, and based on the technical solutions of the present application and the related inspiration of the above embodiments, those skilled in the art can make various alternative improvements and combinations on the above specific embodiments.

Claims

1. A short-range multi-screen interactive system based on pure UWB, comprising at least two terminal devices communicating via pure UWB, characterized in that, Each terminal device includes the following modules and hardware configuration: The device discovery module is used to enable mutual discovery between devices based on the IEEE 802.15.4z protocol. The topology building module is used to build the topology between devices based on the IEEE 802.15.4z HRP mode, achieving topology building with an accuracy of 10cm. When the device moving speed is >1m / s, path prediction based on Kalman filtering is triggered. The video segmentation module is used to segment videos into segments. The pulse modulation module is used to map the H.265 intra-frame prediction mode to the UWB pulse position offset, where Δτ = 2ns / bit, I-frame macroblocks use 3-pulse redundancy coding, and P-frames use single-pulse differential coding. The spatial routing module is used to select spatial routes based on the constructed topology. The multi-screen synchronization module is used to enable synchronized display across multiple screens; The hardware configuration module includes the main control chip, antenna array, and communication protocol support unit.

2. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, The main control chip in the hardware configuration module supports AOA (Angle of Arrival) and ToF (Time of Flight) algorithms, integrates a 6.5GHz center frequency UWB RF front-end, supports HRP mode of the IEEE 802.15.4z protocol, has a pulse repetition frequency (PRF) ≥ 64MHz, has 128KB of built-in SRAM for storing the Kalman filter state matrix of the topology construction, and has a hardware-accelerated path loss calculation unit to calculate the non-line-of-sight propagation path loss PL(dB) = 45 + 20lg(d) in real time, where PL: path loss, d: communication distance, 45: constant term, representing the initial path loss, and 20: path loss exponent.

3. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, The antenna array in the hardware configuration module is a 4×4 MIMO-UWB antenna with a planar inverted-F antenna (PIFA) structure. The bandwidth of a single antenna element is ≥500MHz. The beamforming algorithm is based on the minimum variance distortionless response (MVDR) criterion. A signal gain of ≥12dBi is achieved within a ±15° beamwidth through a digital beam synthesizer. The spacing between adjacent antenna elements is λ / 2, where λ is the wavelength corresponding to the center frequency.

4. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, The device discovery module employs a CSMA / CA contention time slot mechanism during the device registration phase. Specifically, the initial backoff window is 16 time slots, each with a width of 2μs. When channel busy is detected, slots 0-2 are randomly selected. n -1 time slots are used for backoff, where n is the number of backoffs and n≤4; The registration signaling includes the device type identifier, antenna array calibration parameters, and the maximum supported transmission unit.

5. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, The video transmission stage of the pulse modulation module includes a dynamic subcarrier allocation module, which adopts an optimal matching strategy based on the Hungarian algorithm to divide 52 subcarriers into 32 data subcarriers and 20 pilot subcarriers with a subcarrier spacing of 4MHz. It supports orthogonal frequency division multiplexing (OFDM) modulation, and each subcarrier symbol period is 250ns. The pilot subcarriers are used for real-time channel estimation, and the data subcarriers adopt 16-QAM or 64-QAM modulation.

6. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, In the H.265 frame mapping mechanism of the pulse modulation module, the 3-pulse redundancy coding of the I-frame macroblock adopts time diversity technology, the pulse interval is Δτ = 2ns, and each pulse carries 4 bits of position information. The single-pulse differential coding of the P-frame is based on the prediction residual of the previous frame macroblock. When the residual threshold is ≥128, differential coding with pulse position offset Δτ = 4ns is triggered, and the coding efficiency is ≥0.8 bits / pulse.

7. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, The spatial routing module includes a topology database and a dynamic routing table. The topology database stores the real-time distance (accuracy ≤ 10cm), signal strength (RSSI), and number of multipath components between devices. The dynamic routing table adopts the shortest path first (LQ-SPF) algorithm based on link quality. When the link quality index (LQI) is < 80 or the device moving speed is > 1m / s, the routing table is updated, and the update period is ≤ 100ms.

8. The short-range multi-screen interactive system based on pure UWB according to claim 1, characterized in that, The multi-screen synchronization module adopts a timestamp-based distributed synchronization mechanism with a synchronization beacon interval of 1ms, containing a 64-bit timestamp and device ID. It eliminates multipath delay differences through the maximum ratio combining technology of the RAKE receiver, with a synchronization error ≤2ns. It supports master-slave synchronization mode, where the master screen is the time master node and the sub-screen is the slave node.

9. A short-range multi-screen interaction method based on pure UWB, applied to the short-range multi-screen interaction system based on pure UWB as described in any one of claims 1-8, characterized in that, Includes the following steps: Device discovery: The device discovery module enables mutual discovery between devices based on the IEEE 802.15.4z protocol; Topology building: The topology building module is used to build the topology between devices based on the IEEE 802.15.4z HRP mode, achieving topology building with an accuracy of 10cm. When the device moving speed is >1m / s, path prediction based on Kalman filtering is triggered. Video Segmentation: The video is segmented into segments using the video segmentation module; Pulse modulation: The H.265 intra-frame prediction mode is mapped to UWB pulse position offset using the pulse modulation module, where Δτ = 2ns / bit, I-frame macroblocks use 3-pulse redundancy coding, and P-frames use single-pulse differential coding. Spatial routing: The spatial routing module selects spatial routes based on the constructed topology. Multi-screen synchronization: The multi-screen synchronization module enables synchronized display across multiple screens.

10. The short-range multi-screen interaction method based on pure UWB according to claim 9, characterized in that, During the topology construction process, when the device's moving speed is >1m / s, Kalman filter path prediction is triggered, specifically including: Using the position coordinates (x) of the first 3 time points t-2 ,y t-2 ,z t-2 ), (x t-1 ,y t-1 ,z t-1 ), (x t ,y t ,z t ) Calculate the velocity vector (v) x ,v y (vz) and acceleration vector (a) x ,a y ,az); Establish a state-space model: state vector X t =[x t ,v xt ,y t ,v yt ,z t ,vz t ] T State transition matrix: Where Δt is the sampling period = 10ms, (x t ,y t ,z t Let t be the position coordinates of the device in three-dimensional space, and (v) be the position coordinates of the device at time t. xt ,v yt vz t () represents the velocity components of the device in the x, y, and z axes at time t; By measuring equation Z t =HX t +V t Acquire measurement values, where H is the observation matrix and V t For Gaussian noise, the covariance matrix R = diag([0.01, 0.01, 0.01]); Perform prediction and observation updates, and output the predicted position (x) at the next time step. t+1 | t ,y t+1 | t ,z t+1 | t The prediction error is ≤3cm.

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