A Method for Monitoring the Effectiveness of Meteorological Disaster Early Warning Issuance Based on Targeted Receipt Closed Loop

Abstract

This invention relates to the field of meteorological monitoring technology, and more specifically, to a method for monitoring the effectiveness of meteorological disaster early warning dissemination based on a targeted feedback loop, comprising the following steps: Step 1: Acquire meteorological disaster early warning data and establish a list of audience terminal locations; Step 2: Group the audience terminals according to the audience terminal location list to obtain multiple terminal service groups, and transmit the meteorological disaster early warning signal to each audience terminal via a reconfigurable intelligent reflective surface unit; Step 3: Each audience terminal generates meteorological disaster early warning feedback data after receiving the meteorological disaster early warning signal; Step 4: Generate a meteorological disaster early warning dissemination effectiveness monitoring report based on the matching results of the meteorological disaster early warning feedback parsing record and the audience terminal location list.

Description

Technical Field

[0001] This invention belongs to the field of meteorological monitoring technology, specifically relating to a method for monitoring the effectiveness of meteorological disaster early warning dissemination based on a targeted feedback closed loop. Background Technology

[0002] Meteorological disaster early warning is a crucial component of disaster prevention and mitigation efforts. Timely and effective dissemination of early warning information can significantly reduce casualties and property losses caused by meteorological disasters. With the continuous development of meteorological monitoring and communication technologies, meteorological disaster early warning systems have made substantial progress in coverage, transmission speed, and information capacity. Currently, the main channels for disseminating meteorological disaster early warning information include television broadcasts, mobile phone text messages, mobile application push notifications, emergency broadcasting systems, and internet platforms, forming a relatively complete multi-channel early warning information dissemination system.

[0003] However, existing meteorological disaster early warning systems still have several shortcomings in practical applications. Firstly, regarding early warning signal transmission, traditional wireless communication systems use fixed beams or omnidirectional broadcasting to transmit signals, failing to provide targeted signal transmission based on the actual spatial distribution of the target audience. This broadcast-style transmission results in a significant waste of transmission power in unoccupied areas, while target audiences located in building-obstructed areas or signal blind spots struggle to obtain sufficient signal strength. This is particularly problematic in complex urban environments, where signal coverage issues in high-rise buildings, underground spaces, and indoor locations are particularly acute, severely impacting the effective delivery of early warning information. In recent years, reconfigurable smart reflector technology has attracted widespread attention as an emerging wireless communication enhancement technology. Reconfigurable smart reflectors consist of numerous independently adjustable reflective units, capable of actively adjusting the reflection direction of incident electromagnetic waves by changing the electromagnetic characteristics of each unit, thereby achieving intelligent control of the wireless signal propagation path. This technology shows promising application prospects in improving the coverage and transmission efficiency of wireless communication systems. However, existing research on reconfigurable smart reflector applications mainly focuses on data transmission scenarios in mobile communication, with relatively little research specifically targeting the unique application scenario of meteorological disaster early warning. Meteorological disaster early warning is characterized by its suddenness, high timeliness requirements, and dynamic changes in coverage area, which puts forward new technical requirements for beam control strategies and time-sharing scheduling mechanisms of reconfigurable intelligent reflectors. Summary of the Invention

[0004] The main objective of this invention is to provide a method for monitoring the effectiveness of meteorological disaster early warning dissemination based on a targeted feedback closed loop. By using a reconfigurable intelligent reflective surface to achieve precise directional transmission of early warning signals, and by employing differential pulse interval coding to improve the robustness of feedback decoding, a complete targeted feedback closed loop mechanism is constructed. This method can effectively improve the transmission efficiency and coverage of meteorological disaster early warning signals, and achieve accurate quantitative evaluation of early warning dissemination effectiveness.

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

[0006] A method for monitoring the effectiveness of meteorological disaster early warning dissemination based on targeted feedback loops includes the following steps:

[0007] Step 1: Obtain meteorological disaster early warning data, determine the meteorological disaster early warning target area based on the meteorological disaster early warning data, activate the reconfigurable intelligent reflective surface unit and base station equipment deployed in the meteorological disaster early warning target area, obtain the location information of each audience terminal through the base station equipment, and establish an audience terminal location list;

[0008] Step 2: Group the audience terminals according to the audience terminal location list to obtain multiple terminal service groups, generate corresponding beam pointing phase configurations for each terminal service group, and realize beam tracking by switching the beam pointing phase configurations in a time-division manner, so as to transmit the meteorological disaster early warning signal to each audience terminal through the reconfigurable intelligent reflector unit.

[0009] Step 3: After receiving the meteorological disaster warning signal, each audience terminal generates meteorological disaster warning receipt data. The meteorological disaster warning receipt data is then encoded with pulse interval and sent to the base station equipment. The base station equipment decodes the received receipt signal with pulse interval to obtain the meteorological disaster warning receipt parsing record.

[0010] Step 4: Based on the matching results between the meteorological disaster early warning receipt analysis records and the list of audience terminal locations, calculate the meteorological disaster early warning release effectiveness index and generate a meteorological disaster early warning release effectiveness monitoring report.

[0011] Furthermore, the meteorological disaster early warning data includes the disaster type, disaster level, boundary coordinates of the disaster-affected area, and the effective duration of the warning; the audience terminal location list includes the terminal identifier and current three-dimensional spatial coordinates of each audience terminal.

[0012] Furthermore, the reconfigurable smart reflective surface unit includes multiple reflective units arranged in a rectangular shape. Each reflective unit is equipped with a two-state phase modulation device, which has an on state and an off state. When the reflective unit is in the on state, it generates a zero-degree phase shift to the incident electromagnetic wave. When the reflective unit is in the off state, it generates a 180-degree phase shift to the incident electromagnetic wave.

[0013] Furthermore, in step two, the audience terminals are grouped as follows: a rectangular coordinate system is established with the array center of the reconfigurable intelligent reflective surface unit as the origin, and the azimuth and elevation angles of each audience terminal relative to the origin are calculated; the azimuth range is divided into several azimuth intervals, and the elevation range is divided into several elevation intervals, and the combination of each azimuth interval and each elevation interval forms multiple angle grids; audience terminals whose azimuth and elevation angles fall into the same angle grid are grouped into the same terminal service group.

[0014] Furthermore, the method for generating beam pointing phase configuration in step two includes: determining the target pointing angle of each terminal service group, the target pointing angle including the target azimuth angle and the target elevation angle; constructing a phase reversal boundary line based on the target azimuth angle and the target elevation angle, the phase reversal boundary line being a virtual straight line on the reflector array of the reconfigurable intelligent reflector unit, the phase reversal boundary line passing through the geometric center point of the reflector array, and the tilt angle of the phase reversal boundary line being equal to the target azimuth angle.

[0015] Furthermore, the method for generating the beam pointing phase configuration also includes: dividing the reflector array into multiple parallel strip regions along the normal direction of the phase flip boundary line, with the width of each parallel strip region determined by the target elevation angle; alternately numbering each parallel strip region, setting the two-state phase control devices of all reflector units in the odd-numbered parallel strip regions to the on state, and setting the two-state phase control devices of all reflector units in the even-numbered parallel strip regions to the off state, thus forming a beam pointing phase configuration pointing to the corresponding terminal service group.

[0016] Furthermore, the beam tracking in step two is achieved as follows: the effective duration of the warning is divided into multiple transmission time slots equal to the number of terminal service groups, and a corresponding transmission time slot is allocated to each terminal service group; each transmission time slot is further divided into multiple tracking sub-time slots; within each tracking sub-time slot, the beam pointing phase configuration of the corresponding terminal service group is loaded onto the reconfigurable intelligent reflector unit, and a meteorological disaster warning signal is transmitted through the base station equipment; at the switching time of adjacent tracking sub-time slots, the phase reversal boundary line is moved along the normal direction of the phase reversal boundary line by a preset fine-tuning step size, and the state of the two-state phase control device of each reflector unit is updated according to the moved phase reversal boundary line.

[0017] Furthermore, in step three, the meteorological disaster early warning receipt data includes a terminal identifier field and a confirmation status field; the pulse interval encoding adopts a differential pulse interval encoding method, specifically: all bits of the meteorological disaster early warning receipt data are arranged in the order of terminal identifier field first and confirmation status field last to form a receipt bit sequence; a start segment containing a starting reference pulse and a reference interval pulse is generated, the time interval between the starting reference pulse and the reference interval pulse is the reference interval duration; data pulses are generated sequentially for each bit in the receipt bit sequence, when the bit value is zero, the interval duration between the current data pulse and the previous pulse is equal to the previous interval duration, when the bit value is one, the interval duration between the current data pulse and the previous pulse is equal to the previous interval duration plus the reference interval duration; an end segment containing two end marker pulses is generated at the end, forming a complete meteorological disaster early warning receipt pulse sequence.

[0018] Furthermore, in step three, the pulse interval decoding adopts a differential pulse interval decoding method, specifically: pulse detection is performed on the received receipt signal, and the arrival time of each pulse is recorded; the boundary of each receipt record is determined by searching the end marker feature; for each receipt record, the measured interval between adjacent pulses is calculated, and the first measured interval is used as the decoding reference interval; starting from the second measured interval, the difference between the current measured interval and the previous measured interval is calculated. When the absolute value of the difference is less than half of the decoding reference interval, the corresponding bit value is determined to be zero; when the absolute value of the difference is greater than or equal to half of the decoding reference interval, the corresponding bit value is determined to be one; the meteorological disaster early warning receipt parsing record is obtained by parsing the restored bit sequence.

[0019] Furthermore, the method for calculating the meteorological disaster early warning issuance effectiveness index in step four is as follows: match the terminal identifier field in the meteorological disaster early warning receipt parsing record with the terminal identifier in the audience terminal location list, and count the number of successfully matched receipt records as the number of valid receipts; divide the number of valid receipts by the total number of terminals in the audience terminal location list to obtain the early warning reach rate; count the number of records that have been confirmed in the confirmation status field of the meteorological disaster early warning receipt parsing record, and divide the number of records that have been confirmed in the confirmation status field by the number of valid receipts to obtain the early warning response rate.

[0020] The meteorological disaster early warning dissemination effectiveness monitoring method based on targeted feedback closed-loop of the present invention has the following beneficial effects: The present invention groups audience terminals into multiple terminal service groups according to a list of audience terminal locations, and generates corresponding beam pointing phase configurations for each terminal service group, thereby achieving precise directional transmission of meteorological disaster early warning signals. Compared with traditional omnidirectional broadcasting, the present invention can concentrate the transmission power in the actual distribution direction of the audience terminals, effectively improving the received signal strength within the signal coverage area, improving the coverage effect in areas obstructed by buildings and signal blind spots, and thus improving the transmission success rate of meteorological disaster early warning signals.

[0021] This invention employs a beam pointing phase configuration generation method based on phase reversal boundaries and parallel strip region division. It only requires controlling the two-state phase modulation devices of each reflector unit to switch between on and off states to achieve flexible control of the reflected beam pointing direction. Compared to continuous phase control, this two-state phase control method significantly reduces the hardware complexity and control overhead of the reconfigurable intelligent reflector unit, facilitating engineering implementation and large-scale deployment. Simultaneously, by slightly shifting the phase reversal boundaries at the tracking sub-slot switching time, a gradual fine-tuning of the reflected beam pointing angle is achieved, effectively compensating for coverage deviations caused by audience terminal movement and ensuring continuous and stable transmission of warning signals.

[0022] This invention employs differential pulse interval coding to encode and transmit meteorological disaster early warning receipt data, utilizing the variation in the duration of adjacent pulse intervals to represent binary data. This differential coding method has lower requirements for clock synchronization accuracy between the transmitting and receiving ends, effectively addressing clock accuracy differences and clock drift issues among different audience terminals, thus improving the robustness and accuracy of receipt signal decoding. Furthermore, through the rational allocation of receipt transmission time slots, collision interference caused by multiple audience terminals simultaneously transmitting receipt signals is effectively avoided, ensuring the reliability of receipt acquisition. Attached Figure Description

[0023] Figure 1 A schematic diagram illustrating the phase configuration principle of the reconfigurable intelligent reflective surface unit provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram illustrating the movement principle of the phase reversal boundary line during beam tracking, provided in an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the differential pulse interval encoding principle provided in an embodiment of the present invention. Detailed Implementation

[0026] A method for monitoring the effectiveness of meteorological disaster early warning dissemination based on targeted feedback loops includes the following steps:

[0027] Step 1: Obtain meteorological disaster early warning data, determine the meteorological disaster early warning target area based on the meteorological disaster early warning data, activate the reconfigurable intelligent reflective surface unit and base station equipment deployed in the meteorological disaster early warning target area, obtain the location information of each audience terminal through the base station equipment, and establish an audience terminal location list;

[0028] Step 2: Group the audience terminals according to the audience terminal location list to obtain multiple terminal service groups, generate corresponding beam pointing phase configurations for each terminal service group, and realize beam tracking by switching the beam pointing phase configurations in a time-division manner, so as to transmit the meteorological disaster early warning signal to each audience terminal through the reconfigurable intelligent reflector unit.

[0029] Step 3: After receiving the meteorological disaster warning signal, each audience terminal generates meteorological disaster warning receipt data. The meteorological disaster warning receipt data is then encoded with pulse interval and sent to the base station equipment. The base station equipment decodes the received receipt signal with pulse interval to obtain the meteorological disaster warning receipt parsing record.

[0030] Step 4: Based on the matching results between the meteorological disaster early warning receipt analysis records and the list of audience terminal locations, calculate the meteorological disaster early warning release effectiveness index and generate a meteorological disaster early warning release effectiveness monitoring report.

[0031] Meteorological disaster early warning data originates from the meteorological monitoring system, which continuously monitors atmospheric conditions through meteorological observation stations, meteorological satellites, and meteorological radars distributed across various locations. When monitoring results indicate that a meteorological disaster is imminent or is already occurring in a certain area, the meteorological monitoring system generates meteorological disaster early warning data and pushes it to the early warning dissemination system. Meteorological disaster early warning data includes the disaster type, disaster level, boundary coordinates of the disaster-affected area, and the effective duration of the warning. The disaster type identifies the specific type of meteorological disaster targeted by the current warning, such as heavy rain, typhoon, blizzard, strong wind, hail, and lightning. The disaster level reflects the severity of the meteorological disaster and is typically classified into four levels: blue, yellow, orange, and red, with red indicating the most severe disaster. The boundary coordinates of the disaster-affected area are given in the form of a latitude and longitude coordinate sequence, describing the geographical range that the meteorological disaster may affect. The effective duration of the warning indicates the effective duration of this warning information; after this duration, the warning information automatically expires. Typical effective durations range from 30 minutes to 180 minutes, with the specific value determined by the meteorological department based on the speed of disaster evolution.

[0032] In a specific application scenario, suppose a meteorological monitoring system detects that severe convective weather is about to occur in the eastern part of a city, with short-term heavy rainfall and thunderstorms. The meteorological disaster warning data generated by the system at this time shows the disaster type as thunderstorms and strong winds, the disaster level as an orange warning, the boundary coordinates of the disaster-affected area represented by a closed polygon composed of 12 latitude and longitude coordinate points, and the effective warning duration as 60 minutes.

[0033] Based on the boundary coordinates of the disaster-affected area in the meteorological disaster early warning data, the target area for meteorological disaster early warning is determined. The target area for meteorological disaster early warning refers to the geographical area that needs to receive the current meteorological disaster early warning information. In practical applications, the target area for meteorological disaster early warning can be directly the area enclosed by the boundary coordinates of the disaster-affected area, or it can be appropriately expanded. The purpose of expansion is to ensure that recipient terminals located at the edge of the disaster-affected area can receive the early warning information in advance, thus having sufficient time to take preventative measures. The extent of expansion is usually determined according to the type and severity of the disaster. For fast-moving disaster types such as typhoons, the expansion extent can be set to 5 to 10 kilometers; for relatively static disaster types such as blizzards, the expansion extent can be set to 1 to 3 kilometers.

[0034] After identifying the target area for meteorological disaster early warning, it is necessary to activate the reconfigurable smart reflector units and base station equipment deployed within that area. A reconfigurable smart reflector unit is a planar array structure composed of a large number of reflective elements. It can change the reflection direction of incident electromagnetic waves by adjusting the electromagnetic characteristics of each reflective element, thereby achieving active control over the propagation path of wireless signals. Base station equipment is responsible for generating and transmitting meteorological disaster early warning signals and receiving acknowledgment signals from recipient terminals. The deployment locations of reconfigurable smart reflector units are typically chosen on building exteriors, lampposts, communication towers, and other locations with good visibility. The coverage area of ​​each reconfigurable smart reflector unit depends on its size, operating frequency, and deployment height; a typical single reconfigurable smart reflector unit can cover an area with a radius of 200 to 500 meters. In urban environments, the deployment density of reconfigurable smart reflector units is typically 8 to 15 units per square kilometer to ensure adequate coverage of the urban area.

[0035] The activation process first requires determining which reconfigurable smart reflector units are located within the meteorological disaster early warning target area. This determination is achieved by geometrically matching the deployment coordinates of each reconfigurable smart reflector unit with the boundary of the meteorological disaster early warning target area. For reconfigurable smart reflector units whose deployment coordinates fall within the meteorological disaster early warning target area, an activation command is sent to them. Upon receiving the activation command, the reconfigurable smart reflector unit switches its operating state from dormant mode to operating mode and begins responding to control commands from the base station equipment. Simultaneously, the base station equipment associated with these reconfigurable smart reflector units is also activated accordingly, entering the meteorological disaster early warning signal transmission preparation state.

[0036] In one alternative implementation, in addition to activating the reconfigurable smart reflective surface units located within the meteorological disaster early warning target area, reconfigurable smart reflective surface units located within a certain distance outside the boundary of the meteorological disaster early warning target area can also be activated simultaneously. These additionally activated reconfigurable smart reflective surface units can provide better signal coverage for audience terminals located at the edge of the area, improving the transmission reliability of early warning signals.

[0037] After activation, the base station equipment establishes a connection with each audience terminal within the meteorological disaster early warning target area via a wireless communication link to obtain the location information of each audience terminal. Audience terminals refer to devices capable of receiving meteorological disaster early warning signals and presenting warning content to users, including smartphones, tablets, vehicle-mounted terminals, and dedicated early warning receivers. The location information of audience terminals can be obtained in several ways. The first method is for the audience terminal to actively report its Global Navigation Satellite System (GNSS) positioning results. This method has high positioning accuracy, typically reaching 3 to 10 meters. The second method involves the base station equipment measuring the arrival time or angle of arrival of the signals transmitted by the audience terminal and estimating the terminal's location based on the measurement results. This method has relatively lower positioning accuracy, typically within the range of 50 to 200 meters. The third method is a hybrid positioning approach combining the above two methods, selecting an appropriate positioning method based on the capabilities of different audience terminals.

[0038] The base station equipment broadcasts a location reporting request message to all audience terminals within its coverage area. Upon receiving the message, each audience terminal obtains its current location and transmits this location information to the base station equipment via the uplink. The location information includes the audience terminal's current three-dimensional spatial coordinates, where the horizontal coordinates are expressed in latitude and longitude, and the vertical coordinates are expressed as altitude relative to sea level. For audience terminals located in multi-story buildings, obtaining the vertical coordinates helps in subsequent more precise beam pointing control. The base station equipment aggregates the location information received from each audience terminal to establish an audience terminal location list. This list includes each audience terminal's terminal identifier and current three-dimensional spatial coordinates. The terminal identifier is a unique code assigned to each audience terminal, used to identify the source of the receipt data during subsequent receipt parsing. The terminal identifier can be the audience terminal's device serial number, mobile subscriber identification code, or a temporarily assigned number by the system. The current three-dimensional spatial coordinates are stored in either a Cartesian coordinate system or a spherical coordinate system for easy angle calculations later.

[0039] In a specific implementation scenario, assuming there are 3,500 target terminals within the meteorological disaster early warning target area, the base station equipment completes the collection of all target terminal location information within 10 seconds, establishing a target terminal location list containing 3,500 records. Each record occupies 16 bytes of storage space, of which the terminal identifier occupies 8 bytes and the three-dimensional spatial coordinates occupy 8 bytes.

[0040] Based on the current three-dimensional spatial coordinates of each audience terminal in the audience terminal location list, the audience terminals are grouped to obtain multiple terminal service groups. The purpose of grouping is to group audience terminals that are spatially close together, so that audience terminals within the same group can simultaneously obtain services through reflected beams pointing in the same direction. This grouping strategy can effectively reduce the number of beam switchings and improve the transmission efficiency of meteorological disaster early warning signals.

[0041] The grouping process first requires establishing a coordinate system centered on the reconfigurable intelligent reflective surface unit. A Cartesian coordinate system is established with the array center of the reconfigurable intelligent reflective surface unit as the origin. The direction perpendicular to the array plane of the reconfigurable intelligent reflective surface unit and pointing outwards is defined as the positive Z-axis. The horizontal direction within the array plane of the reconfigurable intelligent reflective surface unit is defined as the X-axis, and the vertical direction within the array plane of the reconfigurable intelligent reflective surface unit is defined as the Y-axis. This coordinate system provides a reference for subsequently calculating the angular position of the audience terminal relative to the reconfigurable intelligent reflective surface unit.

[0042] After establishing the coordinate system, calculate the azimuth and pitch angles of each audience terminal relative to the origin. The azimuth angle represents the deflection angle of the audience terminal relative to the positive X-axis in the horizontal plane, ranging from -180 degrees to +180 degrees. The pitch angle represents the upward or downward angle of the audience terminal relative to the horizontal plane, ranging from -90 degrees to +90 degrees. For audience terminals located in front of the origin and above the horizontal plane, the pitch angle is positive; for audience terminals located in front of the origin and below the horizontal plane, the pitch angle is negative.

[0043] Let the coordinates of the audience terminal in the rectangular coordinate system be... Then the azimuth angle of the audience terminal relative to the origin of the coordinate system is... and pitch angle Azimuth can be determined using trigonometric functions. The pitch angle is determined by the projection position of the audience terminal in the horizontal plane formed by the X and Y axes. The angle between the line connecting the audience terminal to the origin of the coordinate system and the horizontal plane is determined.

[0044] After calculating the azimuth and elevation angles of all audience terminals, the terminals are divided into different terminal service groups based on their angle ranges. The azimuth range is divided into several azimuth intervals, and the elevation range is divided into several elevation intervals. In practical applications, considering the effective reflection range limitation of the reconfigurable intelligent reflector unit, the effective azimuth range is typically set to -60 degrees to +60 degrees, and the effective elevation range is also set to -60 degrees to +60 degrees. Audience terminals outside this range are served by other reconfigurable intelligent reflector units.

[0045] Assume the azimuth range (from -60 degrees to +60 degrees) is divided into 12 equal azimuth intervals, each spanning 10 degrees. Similarly, the elevation range (from -60 degrees to +60 degrees) is divided into 12 equal elevation intervals, each spanning 10 degrees. The combination of each azimuth interval and each elevation interval forms multiple angular grids, totaling 144 angular grids. Terminals whose azimuth and elevation angles fall into the same angular grid are grouped into the same terminal service group. In this way, terminal devices with similar spatial locations and angular positions are grouped into the same terminal service group.

[0046] refer to Figure 1In this embodiment, the reconfigurable smart reflective surface unit comprises multiple reflective units arranged in a rectangular pattern, specifically 1024 reflective units in 32 rows by 32 columns. Each reflective unit is equipped with a two-state phase modulation device, which has two operating states: an on state and a off state. When the two-state phase modulation device of the reflective unit is in the on state, the reflective unit generates a zero-degree phase shift in the incident electromagnetic wave. When the two-state phase modulation device of the reflective unit is in the off state, the reflective unit generates a 180-degree phase shift in the incident electromagnetic wave. Figure 1 A rectangular coordinate system was established with the center of the reconfigurable intelligent reflective surface unit array as the origin. The direction perpendicular to the array plane and outward is defined as the positive Z-axis, the horizontal direction within the array plane is defined as the X-axis, and the vertical direction within the array plane is defined as the Y-axis. The directions of the X-axis and Y-axis are marked in the figure.

[0047] The phase reversal boundary is Figure 1 The most crucial geometric element is represented by a virtual straight line passing through the geometric center of the array. The tilt angle of the phase-flip boundary line relative to the X-axis is equal to the target azimuth angle. In this embodiment, the target azimuth angle is set to 25 degrees, therefore the phase-flip boundary line is tilted 25 degrees relative to the X-axis. The position and direction of the phase-flip boundary line are marked with red lines in the figure. The tilt angle of the phase-flip boundary line determines the deflection direction of the reflected beam in the horizontal plane. Along the normal direction of the phase-flip boundary line, the reflector array is divided into multiple parallel strip regions. The parallel strip regions are parallel to the phase-flip boundary line, and adjacent parallel strip regions are closely connected. The boundary lines of some parallel strip regions are marked with blue dashed lines in the figure. The width of the parallel strip region is determined by the target elevation angle; the larger the absolute value of the target elevation angle, the smaller the width of the parallel strip region. In this embodiment, the width of each parallel strip region is approximately 2.5 times the side length of a reflector unit.

[0048] The parallel strip regions are alternately numbered, starting from one side of the array and sequentially labeled as strip 1, strip 2, strip 3, etc. The two-state phase modulation devices of all reflective units located in odd-numbered parallel strip regions are set to the on state, while those of all reflective units located in even-numbered parallel strip regions are set to the off state. Figure 1 In the diagram, white squares represent reflective units in the on-state and dark gray squares represent reflective units in the off-state. This alternating arrangement allows reflective units in adjacent parallel strip areas to generate reflected waves with a 180-degree phase difference, interfering in space to form directional beams pointing in a specific direction. Figure 1Two text boxes are also labeled to explain the phase status of different areas. The text box in the upper right corner indicates that the odd-numbered strips are in the conducting state and have a 0-degree phase shift, while the text box in the lower left corner indicates that the even-numbered strips are in the cut-off state and have a 180-degree phase shift. This phase configuration mode is the core mechanism for achieving beam pointing control. By adjusting the tilt angle of the phase flip boundary line and the width of the parallel strip area, the pointing direction of the reflected beam can be precisely controlled. The tilt angle of the phase flip boundary line controls the azimuth angle of the beam in the horizontal plane, and the width of the parallel strip area controls the elevation angle of the beam relative to the array normal direction. The configuration in this embodiment corresponds to a beam pointing with a target azimuth angle of 25 degrees and a target elevation angle of -5 degrees, which can directionally transmit meteorological disaster warning signals to audience terminals within the corresponding angle range.

[0049] In one alternative implementation, the span of the azimuth and elevation angle intervals can be dynamically adjusted according to the spatial distribution density of the audience terminals. In areas with a dense distribution of audience terminals, a smaller angle interval span, such as 5 degrees, can be used to obtain finer grouping and more concentrated beam coverage; in areas with a sparse distribution of audience terminals, a larger angle interval span, such as 15 degrees or 20 degrees, can be used to reduce the number of terminal service groups and improve transmission efficiency.

[0050] A corresponding beam pointing phase configuration is generated for each terminal service group. The beam pointing phase configuration refers to the state setting scheme of the phase control device of each reflector in the reconfigurable intelligent reflector unit. By setting a specific phase configuration, the reconfigurable intelligent reflector unit can reflect the incident meteorological disaster warning signal to a specified direction, thereby achieving directional coverage of a specific terminal service group.

[0051] The reconfigurable intelligent reflective surface unit comprises multiple reflective units arranged in a rectangular pattern. All reflective units are divided into several columns horizontally and several rows vertically, forming a two-dimensional reflective unit array. Each reflective unit is equipped with a two-state phase modulation device, which has two operating states: on and off. When the two-state phase modulation device of the reflective unit is in the on state, the reflective unit produces a zero-degree phase shift relative to the incident electromagnetic wave, meaning the phase of the reflected wave is the same as the phase of the incident wave. When the two-state phase modulation device of the reflective unit is in the off state, the reflective unit produces a 180-degree phase shift relative to the incident electromagnetic wave, meaning the phase of the reflected wave is flipped relative to the phase of the incident wave.

[0052] In a specific implementation scenario, the reconfigurable smart reflective surface unit comprises 1024 reflective elements arranged in 32 columns by 32 rows, with the spacing between adjacent reflective elements being half the wavelength of the operating electromagnetic wave. Assuming an operating frequency of 5.8 GHz, corresponding to a wavelength of approximately 51.7 mm, the spacing between adjacent reflective elements is approximately 25.9 mm, and the overall size of the reconfigurable smart reflective surface unit is approximately 830 mm by 830 mm.

[0053] The process of generating beam pointing phase configuration first requires determining the target pointing angle for each terminal service group. The target pointing angle includes the target azimuth and target elevation angle, which are taken as the center values ​​of the azimuth and elevation angle intervals of the corresponding angle grid for that terminal service group, respectively. For example, if the angle grid corresponding to a certain terminal service group has an azimuth interval of 20 to 30 degrees and an elevation angle interval of -10 to 0 degrees, then the target azimuth angle for that terminal service group is 25 degrees, and the target elevation angle is -5 degrees.

[0054] A phase-flip boundary line is constructed based on the target azimuth and elevation angles. The phase-flip boundary line is a virtual straight line on the reflector array that divides the array into two regions. The phase-flip boundary line passes through the geometric center of the reflector array, and its tilt angle is equal to the target azimuth angle. Constructing the phase-flip boundary line is a crucial step in achieving beam pointing control; by adjusting the position and tilt angle of the phase-flip boundary line, the pointing direction of the reflected beam can be controlled.

[0055] The physical significance of setting the tilt angle of the phase reversal boundary line to the target azimuth angle is that when the phase reversal boundary line is tilted in a certain direction, the reflected beam will be deflected in a plane perpendicular to that tilt direction. Specifically, when the target azimuth angle is 25 degrees, the phase reversal boundary line is tilted 25 degrees relative to the horizontal direction, and the resulting reflected beam will be deflected in the horizontal plane in the 25-degree direction.

[0056] The reflector array is divided into multiple parallel strip regions along the normal direction of the phase-flip boundary. Each parallel strip region is parallel to the phase-flip boundary, and adjacent parallel strip regions are closely connected, collectively covering the entire reflector array. The width of each parallel strip region is determined by the target elevation angle, because the width of the parallel strip region directly affects the deflection angle of the reflected beam in the elevation direction. There is a corresponding relationship between the width of the parallel strip region and the target elevation angle: the larger the absolute value of the target elevation angle, the smaller the width of the parallel strip region; the smaller the absolute value of the target elevation angle, the larger the width of the parallel strip region.

[0057] The formation mechanism of this correspondence can be understood from the perspective of electromagnetic wave diffraction and interference. When the reflecting units in adjacent parallel strip regions produce reflected waves with opposite phases, these reflected waves will interfere in space. The result of the interference is the formation of the main lobe with the greatest intensity in a specific direction, which is the pointing direction of the reflected beam. The smaller the width of the parallel strip region, the higher the spatial frequency of phase reversal, and the larger the angle between the direction of the main lobe formed by the interference and the normal direction of the array, that is, the larger the pitch angle.

[0058] The parallel strip regions are alternately numbered, starting from one side of the reflective element array, sequentially labeling each parallel strip region as strip 1, strip 2, strip 3, and so on. The two-state phase modulation devices of all reflective elements in the odd-numbered parallel strip regions are set to the ON state, while those in the even-numbered parallel strip regions are set to the OFF state. Through this alternating arrangement, reflective elements in adjacent parallel strip regions generate reflected waves with a phase difference of 180 degrees, forming a beam pointing phase configuration pointing towards the corresponding terminal service group.

[0059] In one alternative implementation, the widths of the parallel strip regions may not be strictly equal, but rather fine-tuned according to the edge effect of the reflective element array. The parallel strip regions located at the edges of the reflective element array can be appropriately widened or narrowed to compensate for the beam sidelobe enhancement problem caused by insufficient number of edge reflective elements.

[0060] Beam tracking is achieved through time-division switching of beam pointing phase configuration, enabling the directional transmission of meteorological disaster warning signals to various target terminals via reconfigurable intelligent reflector units. Time-division switching refers to configuring the reconfigurable intelligent reflector unit with beam pointing phase configurations pointing towards different terminal service groups within different time periods, providing services to each terminal service group sequentially. This method can achieve comprehensive coverage of multiple terminal service groups even with limited hardware resources of the reconfigurable intelligent reflector unit. The effective warning duration is divided into multiple transmission time slots equal to the number of terminal service groups, and a corresponding transmission time slot is allocated to each terminal service group. Assuming the effective warning duration is 60 minutes and the number of terminal service groups is 30, then the duration of each transmission time slot is 2 minutes. Within each transmission time slot, the reconfigurable intelligent reflector unit exclusively provides services to the corresponding terminal service group, directionally transmitting the meteorological disaster warning signal to each target terminal within that terminal service group.

[0061] To further improve beam pointing accuracy and coverage within transmission time slots, each transmission time slot is further divided into multiple tracking sub-time slots. This division allows the reconfigurable smart reflector unit to fine-tune beam direction within the same transmission time slot, compensating for coverage deviations caused by audience terminal movement or coarse angle grid division. Assuming each transmission time slot is divided into 20 tracking sub-time slots, each tracking sub-time slot lasts 6 seconds. Within each tracking sub-time slot, the beam pointing phase configuration for the corresponding terminal service group is loaded into the reconfigurable smart reflector unit. This loading process is completed by the base station equipment sending phase control commands to the reconfigurable smart reflector unit. These commands include the states that the binary phase modulation devices of each reflector unit should be set to. Upon receiving the phase control commands, the reconfigurable smart reflector unit completes the state switching of all reflector units within microseconds, forming a reflected beam pointing towards the current terminal service group.

[0062] The base station equipment transmits meteorological disaster warning signals to the reconfigurable intelligent reflector unit via its transmitting antenna. The meteorological disaster warning signal carries all the information about the meteorological disaster, including the disaster type, disaster level, affected area, and prevention recommendations. After reaching the reconfigurable intelligent reflector unit, the meteorological disaster warning signal is reflected by each reflector unit. Because each reflector unit is configured with a specific phase state according to its beam pointing phase, the reflected waves interfere and superimpose in space, forming a directional beam pointing towards the current terminal service group. The directional beam carries the meteorological disaster warning signal to each recipient terminal within the current terminal service group, and the recipient terminals receive and demodulate the meteorological disaster warning signal through their radio frequency receiving circuits.

[0063] At the switching time of adjacent tracking sub-slots, a minor adjustment is made to the beam pointing phase configuration to achieve progressive beam tracking. The specific method of this minor adjustment is as follows: the phase reversal boundary line is moved along its normal direction by a preset fine-tuning step size. The preset fine-tuning step size is equal to the side length of a single reflective element, approximately 25.9 mm in the aforementioned implementation scenario. After the phase reversal boundary line is moved, some reflective elements originally located within a certain parallel strip region will cross the boundary into an adjacent parallel strip region, thereby changing the parity of their respective parallel strip region numbers. Based on the moved phase reversal boundary line, the parallel strip region to which each reflective element belongs and its parity number are redefined, and the state of the two-state phase modulation device of each reflective element is updated accordingly. For reflective elements whose parity number has changed, the state of their two-state phase modulation device needs to be reversed: those originally in the on state are switched to the off state, and those originally in the off state are switched to the on state.

[0064] By making minute movements of the phase reversal boundary within multiple consecutive tracking sub-slots, the pointing angle of the reflected beam is gradually fine-tuned. Each minute movement results in a small change in beam pointing, and after multiple accumulations, a large-scale beam scan can be achieved. This gradual adjustment method offers better smoothness compared to a one-time large-amplitude switch, preventing signal interruption to recipient terminals receiving meteorological disaster warning signals due to abrupt changes in beam pointing. After all tracking sub-slots have been executed, the current transmission slot ends, and the reconfigurable intelligent reflector unit switches to the beam pointing phase configuration of the terminal service group corresponding to the next transmission slot, continuing to provide services to the next terminal service group. When all transmission slots have been executed, the meteorological disaster warning signal has been transmitted to all recipient terminals within all terminal service groups via time-division beam tracking, completing a full round of warning signal coverage.

[0065] refer to Figure 2 The diagram contains four sub-diagrams, each corresponding to one of four consecutive tracking sub-slots. Within each tracking sub-slot, a reconfigurable smart reflector unit is loaded with a specific beam pointing phase configuration. Progressive beam pointing is achieved by fine-tuning the phase configuration between adjacent tracking sub-slots. Figure 2 The first sub-graph corresponds to tracking sub-slot 1, at which point the phase-flip boundary line is in its initial position, passing through the geometric center of the array. The 32 rows by 32 columns of reflective elements in the array are configured according to the phase-flip boundary line and parallel strip regions. White squares represent the on state, and dark gray squares represent the off state. The phase-flip boundary line is marked with a red line segment, and a green arrow points in the normal direction, indicating that the phase-flip boundary line will move along this direction.

[0066] Figure 2 The second sub-figure corresponds to tracking sub-slot 2. The phase reversal boundary line has moved along the normal direction by a preset fine-tuning step size. The value of the preset fine-tuning step size is equal to the side length of a single reflective unit. After the phase reversal boundary line moves, some reflective units originally located within a certain parallel strip region cross the boundary and enter adjacent parallel strip regions, causing a change in the parity of the numbering of the parallel strip regions to which these reflective units belong. For reflective units whose numbering parity has changed, the state of their binary phase modulation devices needs to be reversed; those originally in the on state switch to the off state, and those originally in the off state switch to the on state. By comparing the first and second sub-figures, it can be observed that the color of some reflective units near the phase reversal boundary line has changed; these reflective units with color changes are the reflective units whose states have reversed.

[0067] Figure 2The third subgraph corresponds to tracking sub-slot 3. The phase flip boundary line continues to move along the normal direction by a fine-tuning step, accumulating a movement distance of two reflection unit side lengths. Compared to the second subgraph, the state of some reflection units is flipped again. As the phase flip boundary line continues to move, the overall position of the parallel strip regions shifts in the normal direction, but the relative relationship between the parallel strip regions remains unchanged, and the width of each parallel strip region also remains unchanged.

[0068] Figure 2 The fourth sub-graph corresponds to tracking sub-slot 4, where the phase reversal boundary line has accumulated a movement distance of three reflective unit side lengths. By comparing the four sub-graphs, the gradual evolution of the phase configuration pattern over time can be clearly observed. The beam pointing change caused by each movement is small; in this embodiment, the beam pointing angle change corresponding to a single movement is approximately 0.5 to 1 degree. Multiple cumulative movements can achieve a larger beam scan range while maintaining the smoothness of beam pointing changes. This gradual beam tracking method has significant advantages over a one-time large-scale switch. When providing services to the same terminal service group within a transmission time slot, fine-tuning through multiple tracking sub-slots can compensate for coverage deviations caused by audience terminal movement or coarse angle grid division, improving the transmission reliability of meteorological disaster warning signals. The movement of the phase reversal boundary line along the normal direction causes a continuous change in the pointing angle of the reflected beam, enabling scanning of all audience terminals within the corresponding angle grid of the coverage terminal service group, avoiding local coverage blind spots caused by fixed beam pointing.

[0069] In one optional implementation, for meteorological disaster warnings with high severity levels, multiple rounds of warning signal coverage can be conducted within the effective duration of the warning. Each round of coverage provides services to all terminal service groups sequentially. Multiple rounds of coverage can improve the transmission reliability of warning signals, ensuring that even if the recipient terminal fails to receive the warning in the first round due to poor channel conditions, it can still obtain meteorological disaster warning information in subsequent rounds.

[0070] After receiving a meteorological disaster warning signal, each audience terminal demodulates and decodes the signal to extract the underlying meteorological disaster warning information. Upon receiving the warning information, each audience terminal needs to send a receipt back to the base station equipment to confirm successful reception. This receipt mechanism is the core of the entire targeted receipt closed loop. By collecting receipt information from each audience terminal, the actual transmission effect of the meteorological disaster warning signal can be accurately assessed. Each audience terminal generates meteorological disaster warning receipt data, which includes a terminal identification field and a confirmation status field. The terminal identification field identifies the source of the receipt data, allowing the base station equipment to identify which audience terminal sent it. The terminal identification field is 8 bits of binary data, capable of representing 256 different terminal identification values ​​from 0 to 255. In application scenarios with more than 256 audience terminals, different audience terminals can be distinguished by dividing the receipt transmission time slots; the specific method will be explained in detail later.

[0071] The confirmation status field indicates the reception and confirmation status of the meteorological disaster warning information by the recipient terminal. The confirmation status field is 2-bit binary data, capable of representing four different states. In one specific implementation, the four values ​​of the confirmation status field are defined as follows: value 00 indicates that the recipient terminal has received the information but the user has not yet viewed it; value 01 indicates that the user has viewed the warning information; value 10 indicates that the user has confirmed that they are aware of the warning content; and value 11 is reserved for future expansion. Through the different values ​​of the confirmation status field, the base station equipment can not only understand whether the meteorological disaster warning signal has been successfully transmitted to the recipient terminal, but also further assess the user's response level to the warning information.

[0072] Each recipient terminal performs pulse interval encoding on the meteorological disaster warning receipt data, converting the binary form of the data into a pulse sequence for transmission via the radio frequency channel. The pulse interval encoding uses differential pulse interval encoding, which uses the variation in the time interval between adjacent pulses to represent binary data, rather than directly using the absolute value of the pulse interval. Differential encoding offers better resistance to clock drift than absolute encoding; even if there is a certain clock deviation between the transmitter and receiver, as long as the deviation remains relatively stable within the encoding period, the receiver can still decode correctly. The first step of differential pulse interval encoding is to arrange all bits of the meteorological disaster warning receipt data in the order of terminal identifier field first, followed by confirmation status field, forming a receipt bit sequence. The terminal identifier field occupies 8 bits, and the confirmation status field occupies 2 bits, therefore the receipt bit sequence contains a total of 10 bits. Each bit in the receipt bit sequence is sequentially labeled as bit 1 to bit 10, where bits 1 to 8 correspond to the terminal identifier field, and bits 9 and 10 correspond to the confirmation status field.

[0073] The second step in differential pulse interval coding is generating the start segment of the acknowledgment pulse sequence. The start segment provides a reference for subsequent differential decoding, enabling the receiver to determine the initial values ​​for differential calculation. The start segment contains a start reference pulse and a reference interval pulse; the time interval between the start reference pulse and the reference interval pulse is defined as the reference interval duration. The reference interval duration is the basic time unit of differential pulse interval coding, and all subsequent interval duration changes are referenced to it. In one specific implementation, the reference interval duration is set to 100 microseconds. The selection of this value requires comprehensive consideration of the time resolution and transmission efficiency of the RF channel. A reference interval duration that is too short will make it difficult for the receiver to accurately distinguish adjacent pulses, while a reference interval duration that is too long will reduce the data transmission rate.

[0074] The third step of differential pulse interval encoding is to perform differential encoding on each bit in the retrieval bit sequence sequentially to generate the corresponding data pulse. The core idea of ​​differential encoding is that the value of the current bit is represented by the change in the current pulse interval duration relative to the previous pulse interval duration. Let the bit currently being encoded be the _th_ ... The bit, whose corresponding generated pulse is the th Data pulse, number The time interval between a data pulse and its preceding pulse is denoted as the first pulse. The interval duration is denoted as . No. The duration of the previous pulse interval of the bit is denoted as When the first When the value of a bit is 0, the first bit... Interval duration Equal to the previous interval duration ,Right now This means that when the bit value is 0, the current pulse interval remains unchanged, without introducing an additional time increment. When the bit value is 0... When the value of bit is 1, the first... Interval duration Equal to the previous interval duration Add the base interval duration, i.e. ,in This indicates the reference interval duration. This means that when the bit value is 1, the current pulse interval is increased by the reference interval duration relative to the previous pulse interval. For the first bit, the previous interval duration is defined as the time interval between the starting reference pulse and the reference interval pulse, i.e., the reference interval duration. Therefore, if the value of the first bit is 0, then the duration of the first interval is... If the value of the first bit is 1, then the duration of the first interval is... Using the above encoding rules, differential encoding of bits 1 to 10 is completed sequentially, generating data pulses 1 to 10. The entire encoding process has a cumulative effect, meaning the interval between subsequent bits depends on the values ​​of all previous bits. If the number of bits with a value of 1 in the retrieval bit sequence is... The duration of the 10th interval This cumulative effect causes different retrieval bit sequences to produce different pulse interval patterns, thereby achieving encoded data transmission.

[0075] The fourth step in differential pulse interval encoding is generating the end segment of the receipt pulse sequence. The end segment marks the end of a complete receipt record, enabling the receiver to correctly distinguish the boundaries of each receipt record when receiving receipt pulse sequences from multiple audience terminals. The end segment contains two end marker pulses. The time interval between the first end marker pulse and the 10th data pulse is four times the base interval length, and the time interval between the second end marker pulse and the first end marker pulse is also four times the base interval length. The reason for choosing four times the base interval length as the end marker interval is that, during normal data encoding, the interval length between adjacent pulses does not exceed a certain multiple of the base interval length (depending on the number of consecutive bit values ​​of 1). Using four times the base interval length as the end marker interval clearly distinguishes it from the interval length generated by normal data encoding, reducing the probability of misjudgment. In the case of the aforementioned 10-bit receipt bit sequence, even if all 10 bits are 1, the 10th interval length is only 11 times the base interval length, which is still significantly different from four times the base interval length. In addition, using two consecutive 4-times-long reference intervals as end markers further reduces the probability of false detections due to channel noise.

[0076] The start segment, data pulses 1 through 10, and the end segment are sequentially connected to form a complete meteorological disaster warning receipt pulse sequence. In a specific example, suppose the terminal identifier of a certain audience terminal is the decimal value 147, the corresponding 8-bit binary representation is 10010011, and the confirmation status field is 10, then the receipt bit sequence is 1001001110. According to the differential pulse interval encoding rule, the pulse interval sequence corresponding to this receipt bit sequence is: 2 times, 2 times, 2 times, 3 times, 3 times, 3 times, 4 times, 5 times, 5 times, 6 times the base interval length, followed by two end marker intervals of 4 times the base interval length.

[0077] refer to Figure 3 The figure illustrates the complete process of converting meteorological disaster early warning receipt data into a pulse sequence using differential pulse interval encoding. Figure 3 The lower part displays a timeline, above which are plotted multiple vertical pulse signals. These pulse signals constitute a complete meteorological disaster warning response pulse sequence. The initial part of the pulse sequence contains two consecutive pulses, and the time interval between these two pulses is defined as the baseline interval length. This reference interval duration serves as a benchmark for subsequent differential coding. In specific implementations, The typical value is 100 microseconds. The selection of this value requires a comprehensive consideration of the balance between the time resolution capability of the radio frequency channel and the data transmission efficiency.

[0078] Following the initial section is the data pulse segment. Figure 3 The middle mark is to The ten data pulses are arranged sequentially. The time interval between each data pulse and the previous pulse carries one bit of information. Figure 3 The upper part displays the acknowledgment bit sequence corresponding to the data pulse segment. This bit sequence is 1001001110, totaling 10 bits. Each bit value in the bit sequence is displayed above the corresponding pulse interval by a box label, with the box for a bit value of 1 marked in green and the box for a bit value of 0 marked in gray. This differentiated visual presentation makes it easy to intuitively understand the mapping relationship between bit values ​​and pulse intervals. Figure 3 The field partitioning structure of the receipt bit sequence is further illustrated. Above the bit sequence, the boundaries of the two data fields are marked by bidirectional arrows. The first field is the terminal identifier field, which occupies the first 8 bits of the receipt bit sequence, i.e., bits 1 to 8. Figure 3The range and name of this field are highlighted in purple. The terminal identifier field uniquely identifies the recipient terminal sending the acknowledgment data; its 8-bit length can represent 256 different terminal identifier values ​​from 0 to 255. The second field is the acknowledgment status field, which occupies the last two bits of the acknowledgment bit sequence, namely bits 9 and 10. Figure 3 The scope and name of this field are highlighted in orange. The confirmation status field is used to indicate the reception and confirmation status of the meteorological disaster warning information by the recipient terminal. The 2-bit field length can represent 4 different statuses, including received but not yet viewed by the user, the user has viewed the warning information, the user has confirmed that they are aware of the warning content, and the reserved extended status.

[0079] Figure 3 The example receipt bit sequence 1001001110 shown below has the following specific meanings: the first 8 bits, 10010011, represent the binary code of the terminal identifier, which corresponds to the decimal value 147; the last 2 bits, 10, indicate that the user has acknowledged and is aware of the warning. Following the data pulse segment is the end marker segment. Figure 3 The image shows two end-marker pulses. The first end-marker pulse coincides with the 10th data pulse. The time interval between them is The time interval between the second end marker pulse and the first end marker pulse is also . The purpose of the end marker segment is to identify the end position of a complete receipt record. The end-marker interval can be clearly distinguished from the interval duration generated by normal data encoding. From Figure 3 It can be observed that the interval between end-marker pulses is significantly larger than the interval between data pulses. This significant difference in interval allows the receiver to reliably identify the boundaries of the acknowledgment record. Figure 3 The distribution of intervals between data pulses reveals that when the corresponding bit value is 0, the current pulse interval is equal to the previous pulse interval; when the corresponding bit value is 1, the current pulse interval increases relative to the previous pulse interval. This differential coding mechanism results in a cumulative increasing characteristic of the pulse interval. Figure 3 Observing from left to right, the interval between data pulses generally shows a gradually increasing trend, which is a typical feature of differential pulse interval coding.

[0080] Each recipient terminal transmits a sequence of meteorological disaster warning response pulses via its radio frequency transmission module according to its assigned response transmission time slot. The allocation of response transmission time slots is designed to prevent signal collisions caused by multiple recipient terminals simultaneously transmitting response pulse sequences. The response transmission time slots are allocated as follows: each recipient terminal determines its response transmission time slot number based on the value of its terminal identifier. Specifically, let the preset total number of time slots be... The terminal identifier value of the audience terminal is Then the receipt sending time slot sequence number of the audience terminal Determined by the following formula: The expression represents the modulo operation. This means dividing the terminal identifier value by the preset total number of time slots, taking the remainder, and then adding 1 to obtain the time slot number. Through the modulo operation, even if the terminal identifier value exceeds the preset total number of time slots, it can still be mapped to a valid time slot number range.

[0081] In one specific implementation, the total number of preset time slots is set to 64, and the duration of each receipt transmission time slot is 50 milliseconds. For the audience terminal with a terminal identifier value of 147, its receipt transmission time slot sequence number is... This means that the recipient terminal transmits a meteorological disaster warning feedback pulse sequence within the 20th feedback transmission slot. After being transmitted by the recipient terminal's radio frequency transmission module, the meteorological disaster warning feedback pulse sequence is reflected by a reconfigurable intelligent reflector unit and transmitted to the base station equipment. During the feedback acquisition phase, the reconfigurable intelligent reflector unit can be configured in wide-angle reflection mode to reflect feedback signals from all directions to the base station equipment, ensuring that the feedback pulse sequences sent by each recipient terminal can be received by the base station equipment.

[0082] The base station equipment receives meteorological disaster warning receipt pulse sequences from various audience terminals, forming a receipt pulse aggregation signal. This signal contains meteorological disaster warning receipt pulse sequences sent by multiple audience terminals within their respective receipt transmission slots. The base station equipment performs pulse interval decoding on the aggregation signal, restoring the pulse sequence form of the receipt signal to a binary form meteorological disaster warning receipt parsing record. The pulse interval decoding uses a differential pulse interval decoding method, corresponding to the differential pulse interval encoding method at the transmitting end. The first step of differential pulse interval decoding is pulse detection on the received receipt signal. The purpose of pulse detection is to identify the position of each pulse in the aggregation signal and record the arrival time of each pulse. Pulse detection can be achieved using a threshold comparison method: the amplitude of the aggregation signal is compared with a preset detection threshold; when the signal amplitude exceeds the threshold, a pulse is determined to exist, and this time is recorded as the pulse arrival time. The result of pulse detection is a pulse time sequence, recording the arrival times of all detected pulses in the aggregation signal.

[0083] The second step in differential pulse interval decoding is to search for end-marker features in the pulse time sequence to determine the boundaries of each receipt record. The end-marker feature is defined as the position where two consecutive pulse intervals are close to four times the reference interval length. During the search, the time intervals between adjacent pulses in the pulse time sequence are calculated sequentially. When two consecutive time intervals are found to fall within the tolerance range of approximately four times the reference interval length, that position is determined to be the end boundary of a receipt record. The tolerance range needs to consider the effects of channel transmission delay jitter and clock skew; a typical tolerance range is ±20% of the reference interval length.

[0084] The third step in differential pulse interval decoding is to extract the pulse times from the end boundary of each receipt record and calculate the measured interval between adjacent pulses. A complete meteorological disaster warning receipt pulse sequence contains 2 pulses in the initial segment, 10 pulses in the data segment, and 2 pulses in the ending segment, totaling 14 pulses. Thirteen pulse times are extracted from the end boundary (excluding the time after the last end marker pulse), and the 12 measured intervals between adjacent pulses are calculated, denoted as follows: ,in and The interval between the two end markers, The reference interval corresponding to the starting segment, to The encoding interval corresponds to 10 data bits.

[0085] The first measured interval duration This serves as the decoding reference interval for that receipt record. Because... Using the reference interval duration corresponding to the transmitting end as the decoding reference interval can adaptively compensate for the clock deviation between the transmitting and receiving ends. Even if the clock frequencies of different audience terminals differ, as long as the clock frequency of the same audience terminal remains stable during the transmission of a single receipt pulse sequence, the receiving end can use the first interval duration of that receipt record as the decoding reference to correctly reconstruct the bit sequence. The fourth step of differential pulse interval decoding is to perform differential decoding sequentially starting from the second measured interval duration to reconstruct the receipt bit sequence. The core operation of differential decoding is to calculate the difference between the current measured interval duration and the previous measured interval duration, and determine the value of the corresponding bit based on the magnitude of the difference. Let the bit currently being decoded be the _ ... Bits, whose corresponding measured interval duration is (Because the first measured interval duration is used to determine the decoding reference interval, and the second measured interval duration corresponds to the first bit), the previous measured interval duration is... The decoding reference interval is .

[0086] Calculate the difference When the difference The absolute value is less than the decoding reference interval. When it is half, that is At that time, the judgment of the first The value of the bit is 0. When the difference... The absolute value is greater than or equal to the decoding reference interval. When it is half, that is At that time, the judgment of the first The bit value is 1. The reason for choosing half of the decoding reference interval as the decision threshold is that, according to the differential pulse interval coding rule, when the bit value is 0, the current interval duration equals the previous interval duration, and the theoretical difference is 0; when the bit value is 1, the current interval duration is greater than the previous interval duration by the reference interval duration, and the theoretical difference is the reference interval duration. Setting the decision threshold to half of the reference interval duration is precisely at the midpoint of the theoretical difference between the two cases, maximizing the probability of a correct decision even in the presence of noise interference.

[0087] Differential decoding is performed sequentially for the 2nd to 11th measured intervals, restoring bits 1 through 10. Bits 1 through 8 are then parsed into a terminal identifier field, and bits 9 through 10 are parsed into an acknowledgment status field, forming a meteorological disaster warning receipt parsing record. This record contains both a terminal identifier field and an acknowledgment status field, and has the same data structure as the meteorological disaster warning receipt data from the sending end.

[0088] In one alternative implementation, an error correction mechanism can be introduced during differential pulse interval decoding. For example, a cyclic redundancy check (CRC) bit can be added during encoding, and the restored bit sequence can be checked during decoding to detect any transmission errors. If an error is detected, the corresponding recipient terminal can be requested to resend the meteorological disaster warning receipt pulse sequence, or the receipt record can be marked as invalid.

[0089] Based on the matching results between the meteorological disaster early warning receipt parsing records and the audience terminal location list, the effectiveness index of meteorological disaster early warning issuance is calculated. The calculation of the effectiveness index is a crucial step in evaluating the effectiveness of meteorological disaster early warning issuance. By quantitatively analyzing the transmission coverage and user response of the early warning signal, it provides data support for subsequent early warning issuance strategy optimization. The first step in calculating the effectiveness index is to match the terminal identifier field in the meteorological disaster early warning receipt parsing records with the terminal identifiers in the audience terminal location list. The purpose of matching is to verify the validity of the receipt data, ensuring that each receipt data comes from an audience terminal registered in the audience terminal location list. The matching process uses an exact matching method: for each meteorological disaster early warning receipt parsing record, a record with the same terminal identifier field value is searched in the audience terminal location list. If a matching record is found, the meteorological disaster early warning receipt parsing record is determined to be a valid receipt; if no matching record is found, the meteorological disaster early warning receipt parsing record may be due to a transmission error causing an incorrect decoding of the terminal identifier field, and is therefore determined to be an invalid receipt and discarded.

[0090] The number of successfully matched receipt records is counted and taken as the number of valid receipts. The number of valid receipts reflects the number of audience terminals that successfully received receipt information and is the foundational data for calculating the alert reach rate. The second step in calculating the performance indicator is to calculate the alert reach rate. The alert reach rate is defined as the ratio of the number of valid receipts to the total number of terminals in the audience terminal location list, calculated as follows: ,in Indicates the early warning reach rate. Indicates the number of valid receipts. This indicates the total number of terminals in the audience terminal location list. The warning reach rate ranges from 0 to 1. The closer the value is to 1, the better the coverage of the meteorological disaster warning signal, and the higher the proportion of audience terminals that successfully received the warning information and returned a receipt.

[0091] In a specific example, suppose the audience terminal location list contains records of 3500 audience terminals. The base station equipment receives and successfully decodes 3280 meteorological disaster early warning receipt parsing records, of which 3150 records have terminal identifier fields that successfully match the terminal identifiers in the audience terminal location list. Therefore, the number of valid receipts is 3150, and the early warning reach rate is... This means that 90% of the audience terminals successfully received the meteorological disaster warning signal and returned a valid receipt.

[0092] The third step in calculating performance indicators is to calculate the early warning response rate. The early warning response rate measures how many users among the recipient terminals who successfully received meteorological disaster early warning information confirmed the warning information. Calculating the early warning response rate first requires counting the number of records in the meteorological disaster early warning receipt parsing records where the confirmation status field indicates confirmation. According to the definition of the confirmation status field mentioned above, a value of 10 indicates that the user has confirmed that they are aware of the warning content. The number of records with a confirmation status field value of 10 among all valid receipt records is counted and recorded as the number of confirmed records.

[0093] The early warning response rate is defined as the ratio of the number of confirmed records (represented by the confirmation status field) to the number of valid receipts. The formula is: ,in Indicates the early warning response rate. The confirmation status field indicates the number of records that have been confirmed. This indicates the number of valid response receipts. The warning response rate also ranges from 0 to 1, with a value closer to 1 indicating a higher level of user response to meteorological disaster warning information. Continuing the previous example, suppose that out of 3150 valid response receipt records, 2835 records have a confirmation status field value of 10, indicating that the user has confirmed that they are aware of the warning content. Then the warning response rate is... This means that 90% of users who received the warning message acknowledged and responded to it.

[0094] The early warning reach rate and early warning response rate are stored in the meteorological disaster early warning effectiveness monitoring database to generate a meteorological disaster early warning issuance effectiveness monitoring report. The meteorological disaster early warning effectiveness monitoring database is used for long-term storage of the effectiveness evaluation results of each meteorological disaster early warning issuance, facilitating historical data analysis and trend tracking. The meteorological disaster early warning issuance effectiveness monitoring report is a comprehensive evaluation document of the effectiveness of this meteorological disaster early warning issuance. The report content includes, but is not limited to: basic information about this meteorological disaster early warning (disaster type, disaster level, early warning issuance time, early warning effective duration, etc.), a description of the scope of the meteorological disaster early warning target area, the total number of terminals in the audience terminal location list, the number of valid responses, the early warning reach rate, the confirmation status field indicating the number of confirmed records, and the early warning response rate.

[0095] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for monitoring the effectiveness of meteorological disaster early warning dissemination based on targeted feedback closed loop, characterized in that, Includes the following steps: Step 1: Obtain meteorological disaster early warning data, determine the meteorological disaster early warning target area based on the meteorological disaster early warning data, activate the reconfigurable intelligent reflective surface unit and base station equipment deployed in the meteorological disaster early warning target area, obtain the location information of each audience terminal through the base station equipment, and establish an audience terminal location list; Step 2: Group the audience terminals according to the audience terminal location list to obtain multiple terminal service groups, generate corresponding beam pointing phase configurations for each terminal service group, and realize beam tracking by switching the beam pointing phase configurations in a time-division manner, so as to transmit the meteorological disaster early warning signal to each audience terminal through the reconfigurable intelligent reflector unit. The method for generating the beam pointing phase configuration is as follows: Determine the target pointing angle for each terminal service group. The target pointing angle includes the target azimuth angle and the target elevation angle. A phase reversal boundary line is constructed based on the target azimuth and target elevation angles. The phase reversal boundary line is a virtual straight line on the reflective unit array of the reconfigurable intelligent reflective surface unit. The phase reversal boundary line passes through the geometric center point of the reflective unit array, and the tilt angle of the phase reversal boundary line is equal to the target azimuth. Along the normal direction of the phase reversal boundary line, the reflective element array is divided into multiple parallel strip regions, and the width of each parallel strip region is determined by the target elevation angle. Each parallel strip region is alternately numbered. The two-state phase modulation devices of all reflection units in the odd-numbered parallel strip regions are set to the on state, and the two-state phase modulation devices of all reflection units in the even-numbered parallel strip regions are set to the off state, thus forming a beam pointing phase configuration pointing to the corresponding terminal service group. Step 3: After receiving the meteorological disaster warning signal, each audience terminal generates meteorological disaster warning receipt data. The meteorological disaster warning receipt data is then encoded with pulse interval and sent to the base station equipment. The base station equipment decodes the received receipt signal with pulse interval to obtain the meteorological disaster warning receipt parsing record. Step 4: Based on the matching results between the meteorological disaster early warning receipt analysis records and the list of audience terminal locations, calculate the meteorological disaster early warning release effectiveness index and generate a meteorological disaster early warning release effectiveness monitoring report.

2. The method according to claim 1, characterized in that, Meteorological disaster early warning data includes disaster type, disaster level, boundary coordinates of disaster-affected area, and effective warning duration; the audience terminal location list includes the terminal identifier and current three-dimensional spatial coordinates of each audience terminal.

3. The method according to claim 1, characterized in that, The reconfigurable intelligent reflective surface unit comprises multiple reflective units arranged in a rectangular shape. Each reflective unit is equipped with a two-state phase modulation device, which has an on state and an off state. When the reflective unit is in the on state, it generates a zero-degree phase shift to the incident electromagnetic wave. When the reflective unit is in the off state, it generates a 180-degree phase shift to the incident electromagnetic wave.

4. The method according to claim 1, characterized in that, In step two, the audience terminals are grouped as follows: a rectangular coordinate system is established with the array center of the reconfigurable intelligent reflective surface unit as the origin, and the azimuth and elevation angles of each audience terminal relative to the origin are calculated; the azimuth range is divided into several azimuth intervals, and the elevation range is divided into several elevation intervals. The combination of each azimuth interval and each elevation interval forms multiple angle grids; audience terminals whose azimuth and elevation angles fall into the same angle grid are grouped into the same terminal service group.

5. The method according to claim 1, characterized in that, The beam tracking in step two is achieved as follows: the effective duration of the warning is divided into multiple transmission time slots equal to the number of terminal service groups, and a corresponding transmission time slot is allocated to each terminal service group; each transmission time slot is further divided into multiple tracking sub-time slots; within each tracking sub-time slot, the beam pointing phase configuration of the corresponding terminal service group is loaded onto the reconfigurable intelligent reflector unit, and a meteorological disaster warning signal is transmitted through the base station equipment; at the switching time of adjacent tracking sub-time slots, the phase reversal boundary line is moved along the normal direction of the phase reversal boundary line by a preset fine-tuning step size, and the state of the two-state phase control device of each reflector unit is updated according to the moved phase reversal boundary line.

6. The method according to claim 1, characterized in that, In step three, the meteorological disaster early warning receipt data includes a terminal identifier field and a confirmation status field. The pulse interval encoding adopts a differential pulse interval encoding method, specifically: all bits of the meteorological disaster early warning receipt data are arranged in the order of terminal identifier field first and confirmation status field last to form a receipt bit sequence; a start segment containing a starting reference pulse and a reference interval pulse is generated, and the time interval between the starting reference pulse and the reference interval pulse is the reference interval duration; data pulses are generated sequentially for each bit in the receipt bit sequence. When the bit value is zero, the interval duration between the current data pulse and the previous pulse is equal to the previous interval duration. When the bit value is one, the interval duration between the current data pulse and the previous pulse is equal to the previous interval duration plus the reference interval duration; an end segment containing two end marker pulses is generated at the end to form a complete meteorological disaster early warning receipt pulse sequence.

7. The method according to claim 6, characterized in that, In step three, the pulse interval decoding adopts the differential pulse interval decoding method, specifically: pulse detection is performed on the received receipt signal, and the arrival time of each pulse is recorded; the boundary of each receipt record is determined by searching the end marker feature; for each receipt record, the measured interval between adjacent pulses is calculated, and the first measured interval is used as the decoding reference interval; starting from the second measured interval, the difference between the current measured interval and the previous measured interval is calculated. When the absolute value of the difference is less than half of the decoding reference interval, the corresponding bit value is determined to be zero; when the absolute value of the difference is greater than or equal to half of the decoding reference interval, the corresponding bit value is determined to be one; the meteorological disaster early warning receipt parsing record is obtained by parsing the restored bit sequence.

8. The method according to claim 1, characterized in that, The method for calculating the effectiveness index of meteorological disaster early warning issuance in step four is as follows: match the terminal identifier field in the meteorological disaster early warning receipt parsing record with the terminal identifier in the audience terminal location list, and count the number of successfully matched receipt records as the number of valid receipts; divide the number of valid receipts by the total number of terminals in the audience terminal location list to obtain the early warning reach rate; count the number of records that have been confirmed in the confirmation status field of the meteorological disaster early warning receipt parsing record, and divide the number of records that have been confirmed in the confirmation status field by the number of valid receipts to obtain the early warning response rate.

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