Base station-free large-area water rescue active search and positioning equipment system and methods
By constructing a local wireless coverage network that does not rely on a public network and working in conjunction with phased array radar, high-precision, low-cost, and traceable non-cooperative terminal positioning is achieved in extreme scenarios. This solves the problems of insufficient positioning accuracy and high cost in existing technologies and is suitable for grassroots emergency rescue.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENYANG FIRE RES INST OF MEM
- Filing Date
- 2026-03-09
- Publication Date
- 2026-06-02
AI Technical Summary
In extreme scenarios such as natural disasters or loss of communication in the wild, such as water, power, and internet outages, existing positioning technologies are unable to achieve high-precision, low-cost positioning of non-cooperative terminals. Furthermore, existing emergency communication platforms are costly and have long deployment cycles, failing to meet the needs of high-frequency, small-scale rescue operations at the grassroots level.
A local wireless coverage network without public network dependence is constructed. The base station module autonomously generates cell signaling to actively search for terminals, enhances uplink signals, and performs direction and distance measurement through phased array radar. Combined with scheduling information, high-precision positioning is achieved.
It enables proactive detection of non-cooperative targets, significantly improves search and rescue success rate, enhances positioning accuracy and signal-to-noise ratio, supports multi-target management, achieves high-security device traceability, and builds a low-cost, fast-response grassroots emergency response capability.
Smart Images
Figure CN122138251A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wireless positioning technology, and in particular to a base station-free active search and positioning equipment system and method for large-area water rescue. Background Technology
[0002] In extreme scenarios involving natural disasters (such as earthquakes, floods, and landslides) or loss of contact in the wild, where there is no water, electricity, or internet access, quickly locating missing persons is the primary task of emergency rescue. Currently, the main search and rescue methods include manual patrols, optical / thermal imaging drone searches, and the restoration of public network signals by large-scale emergency communication platforms.
[0003] Manual patrols rely on rescuers searching along the shore on foot or by boat, which is inefficient, has limited coverage, and poses a high safety risk in complex terrain or waters. While consumer or industrial drones can provide aerial vision, they rely on visible light or infrared imaging, which significantly reduces their identification ability in rain, fog, at night, in dense vegetation, or in environments with strong water surface reflection. Furthermore, they cannot detect targets that have fallen into the water, are obscured, or are in environments with similar body temperatures.
[0004] In recent years, high-altitude long-endurance emergency communication drones, represented by the "Wing Loong-2H," have been used for post-disaster communication restoration. By carrying airborne base stations, they achieve localized 4G / 5G signal coverage, enabling missing persons to make calls or report their location. However, the cost of a single mission for this type of platform can reach hundreds of thousands of yuan, the deployment cycle is long (usually 1-2 hours), and it is only suitable for major national-level disasters, making it difficult to meet the high-frequency, small-scale rescue needs at the grassroots level (such as lost hikers, lost elderly people, and people falling into water).
[0005] On the other hand, existing wireless positioning technologies also face severe challenges in the absence of base stations. Traditional GPS / BeiDou positioning signals are interrupted indoors or in sheltered environments such as canyons; Wi-Fi / Bluetooth positioning relies on pre-deployed infrastructure and cannot be used at disaster sites; and ranging models based on received signal strength (RSS) are severely affected by environmental factors such as multipath propagation, shadow fading, and human occlusion, resulting in positioning errors often exceeding 100 meters, making it difficult to support accurate search and rescue.
[0006] Although phased array radars possess high-precision direction-finding capabilities, they are typically used for target detection rather than communication terminal identification, thus failing to acquire user identity information. Furthermore, their signal-to-noise ratio is insufficient in weak uplink signal scenarios, making reliable acquisition difficult. Simultaneously, existing single-station positioning systems generally lack precise ranging methods, relying heavily on unstable RSS models, which limits overall positioning accuracy.
[0007] Therefore, there is an urgent need for a new positioning technology that does not rely on public network infrastructure, can actively detect non-cooperative terminals, has both high-precision direction finding and ranging capabilities, and is cost-controllable, in order to fill the capability gap of the current emergency search and rescue system under the condition of "three interruptions". Summary of the Invention
[0008] To address the aforementioned problems, the present invention aims to provide a base station-free active search and positioning equipment system and method for large-area water rescue.
[0009] This invention provides a method for active search and positioning equipment for large-area water rescue without base stations, comprising: Construct a local wireless coverage network that does not rely on the public network. The local wireless coverage network includes a base station module. The base station module is used to autonomously generate and broadcast cell signaling to form a local wireless communication cell in order to actively search for and capture mobile terminals that are powered on in the surrounding area. The base station module can access any disconnected mobile terminal and enhance the uplink signal of the mobile terminal. The communication scheduling information of the base station module is acquired and recorded in real time. The scheduling information is used to guide the reception process of mobile terminals within the coverage area to obtain signal data; Based on the signal data, the target lost terminal is subjected to direction and distance measurement to obtain the azimuth and distance information corresponding to the target lost terminal; The absolute geographical latitude and longitude of the target lost terminal is calculated based on the orientation and distance information.
[0010] Optionally, accessing any disconnected mobile terminal based on the base station module and enhancing the uplink signal of the mobile terminal includes: Receive a random access request initiated by a lost mobile terminal, wherein the random access request is automatically initiated by the lost mobile terminal after detecting the signal of the wireless communication cell; In response to the random access request, a temporary link is established with the mobile terminal, and the mobile terminal is forced to continuously transmit a specific uplink reference signal at maximum transmit power through a valid Radio Resource Control (RRC) signaling or Transmit Power Control (TPC) command.
[0011] Optionally, the scheduling information includes: the cell radio network temporary identifier (C-RNTI), the uplink transmission subframe number, and the allocated physical resource block (RB).
[0012] Optionally, guiding the reception process of mobile terminals within the coverage area using the scheduling information includes: In the time domain, data acquisition is only initiated within a specific subframe window where the target disconnected terminal is scheduled. In the frequency domain, only the signal within the PRB bandwidth occupied by the target lost terminal is extracted; In the user domain, signals are identified using C-RNTI.
[0013] Optionally, direction finding of the target lost terminal includes: The direction of arrival (DOA) of the signal is calculated using the MUSIC super-resolution algorithm for multiple signal classification, and the estimated azimuth angle is obtained as the azimuth information corresponding to the target lost terminal.
[0014] Optionally, ranging the target lost terminal includes: The base station module records the transmission time that triggers the target disconnected terminal to send an uplink signal, and shares the time with the phased array radar module through a hardware-level time synchronization interface; When the phased array radar module receives the uplink signal, it records the arrival time; based on the transmission time, arrival time and the speed of light, it calculates the straight-line distance between the target lost terminal and the phased array radar module, which is used as the distance information corresponding to the target lost terminal.
[0015] Optionally, calculating the absolute geographical latitude and longitude of the target lost terminal based on the orientation information and distance information includes: The azimuth information is used in conjunction with the north offset angle calibrated during antenna installation to convert it into a true azimuth angle based on geographic true north. Let the geographical coordinates of the phased array radar module be ( , If the target slant distance is d meters, then the target latitude and longitude ( , ), calculated using the forward spherical solution formula: R=6371000m
[0016] .
[0017] The present invention also provides a base station-free active search and positioning equipment system for performing the base station-free active search and positioning equipment method for large-area water rescue as described in any of the above claims. The system has a local wireless coverage network that does not rely on a public network, and the local wireless coverage network includes a base station module and a phased array radar module.
[0018] This invention achieves reliable acquisition of mobile phone IMSI by constructing wireless signal cells and, by combining the collaborative working mechanism of wireless communication base stations and phased array radar, proposes a novel large-area, high-precision, and non-intrusive personnel positioning scheme. Compared with existing technologies, this invention has achieved significant technological advancements in positioning performance, deployment cost, management efficiency, and system compliance. Specific technical effects are as follows: (1) It has achieved the capability of active detection of non-cooperative targets. This invention eliminates the need for missing persons to actively make phone calls or use an app to call for help; their mobile phones only need to be switched on. By actively inducing and forcing terminals to transmit enhanced signals through self-built cell networks, it fundamentally solves the fatal flaw of traditional emergency communication platforms that rely on "passive waiting," significantly improving the success rate of search and rescue in scenarios where people are unconscious or incapacitated.
[0019] (2) Significantly improved single-station positioning accuracy and robustness By abandoning the RSS ranging model, which is susceptible to environmental interference, we innovatively adopt a time-synchronization-based time-of-arrival (ToA) ranging method. It effectively avoids the effects of multipath propagation, water surface reflection, and human body obstruction. Combined with the MUSIC super-resolution direction finding algorithm, it achieves high-precision positioning, far superior to traditional single-station positioning schemes.
[0020] (3) Reliable signal acquisition under high signal-to-noise ratio was achieved. By utilizing precise scheduling information (C-RNTI, subframe number, RB position) obtained from the base station, the phased array radar is guided to perform three-dimensional focusing reception based on space, time, and frequency. This mechanism concentrates signal processing resources on the target signal, greatly suppressing background noise and asynchronous interference, thereby significantly improving the acquisition probability and measurement reliability of weak uplink signals.
[0021] (4) Achieved precise multi-objective management with traceable identity. The system binds the positioning results to the specific user identity through C-RNTI / IMSI, which can not only distinguish multiple concurrent targets, but also provide clear identity information for rescue command, support the allocation of rescue resources according to priority, and avoid the limitation of traditional radar or optical methods that "can only see the shadow but do not know who it is".
[0022] (5) A low-cost, rapid-response grassroots emergency response capability has been established. This system does not rely on expensive satellites, high-altitude long-endurance drones, or public network infrastructure. It can be integrated into vehicle-mounted or portable platforms, has a short deployment time (<10 minutes), and low cost per mission. It perfectly meets the needs of grassroots fire departments, public security bureaus, water rescue teams, and other units for high-frequency, small-scale search and rescue missions, filling the capability gaps in the existing emergency response system.
[0023] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description
[0024] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a schematic diagram of the method for active search and positioning equipment for large-area water rescue without base stations according to an embodiment of the present invention; Figure 2 This is a schematic diagram of a base station-free, large-area water rescue active search and positioning equipment system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the installation of the base station-free large-area water rescue active search and positioning equipment system according to an embodiment of the present invention; Figure 4 This is a distribution map of mobile terminals on the lake surface in an application case of the present invention; Figure 5 This is a schematic diagram of the positioning results in an application case of the present invention; Figure 6 This is a schematic diagram of the system deployment in an application example of the present invention. Detailed Implementation
[0025] The embodiments of the present invention are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the present invention and are not restrictive.
[0026] This invention provides a method for active search and positioning equipment for large-area water rescue without base stations, such as... Figure 1 As shown, the base station-free large-area water rescue active search and positioning equipment method of this embodiment includes the following steps S1~S6.
[0027] S1: Construct a local wireless coverage network that does not rely on the public network. The local wireless coverage network includes a base station module. The base station module is used to autonomously generate and broadcast cell signaling to form a local wireless communication cell in order to actively search for and capture mobile terminals that are powered on in the surrounding area. S2: Access any disconnected mobile terminal based on the base station module and enhance the uplink signal of the mobile terminal; S3: Real-time acquisition and recording of communication scheduling information of the base station module; S4: Use scheduling information to guide the reception process of mobile terminals within the coverage area to obtain signal data; S5: Based on signal data, perform direction and distance measurement on the target lost terminal to obtain the azimuth and distance information of the target lost terminal; S6: Calculate the absolute geographical latitude and longitude of the target missing terminal based on the orientation and distance information.
[0028] This invention's method for active search and positioning equipment in large-area water rescue without a base station allows for the rapid deployment of a lightweight base station module in situations of "three disruptions"—water, power, and internet outages. The base station module includes a baseband board, a power amplifier module, a filter, and an antenna feeder system. The radio frequency signal generated by the baseband board is amplified by the power amplifier module and then broadcast externally through the antenna feeder system. This base station module can autonomously generate and broadcast LTE cell signaling (including the Master Information Block (MIB) and System Information Block (SIB)) compliant with 3GPP standards, forming a local wireless communication cell for actively searching for and capturing nearby mobile terminals that are powered on. The base station module in this embodiment can broadcast LTE cell signals compliant with 3GPP standards within a preset frequency band. Mobile terminals within this area will automatically scan for this signal and initiate a random access request according to the standard access procedure, completing a temporary connection with the self-built cell.
[0029] This invention, through the construction of local wireless cells in "three-disruption" scenarios, induces mobile terminals to transmit enhanced uplink signals and coordinates with phased array radar to achieve high-precision direction and ranging. Finally, by combining scheduling information and identification, it achieves precise, traceable, and multi-target positioning. This system features fast response, low cost, and accurate positioning, making it suitable for grassroots emergency rescue.
[0030] In an optional embodiment of the present invention, step S3 above, which involves the base station module accessing any lost mobile terminal and enhancing the uplink signal of the mobile terminal, includes: receiving a random access request initiated by the lost mobile terminal, wherein the random access request is automatically initiated by the lost mobile terminal after detecting the signal of the wireless communication cell; responding to the random access request, establishing a temporary link with the mobile terminal, and forcing the mobile terminal to continuously transmit a specific uplink reference signal at maximum transmit power through a valid Radio Resource Control (RRC) signaling or Transmit Power Control (TPC) command.
[0031] In other words, in the "three-disconnection" scenario, the mobile terminal is in a state of no signal. The mobile terminal will actively search for available cell signals in the surrounding environment. When the disconnected mobile terminal detects a self-built cell signal, it will automatically initiate a random access request. The base station module responds to this request, establishes a temporary connection with the terminal, and forces the terminal to continuously transmit a specific uplink reference signal (such as a sounding reference signal, SRS) at maximum transmit power through a valid Radio Resource Control (RRC) signaling or Transmit Power Control (TPC) command. The base station module can trigger the connected terminal to continuously transmit uplink reference signals (such as SRS) through valid signaling (such as periodic IdentityRequest) and force it to transmit at maximum power through TPC commands. This significantly improves the detectability of the terminal's uplink signal, creating favorable conditions for subsequent radar reception.
[0032] In this embodiment of the invention, during interaction with the terminal, the base station module acquires and records key communication scheduling information in real time, including but not limited to: the terminal's Cell Radio Network Temporary Identifier (C-RNTI), the precise subframe number of the uplink signal being scheduled, and the allocated Physical Resource Block (PRB) frequency band location. This information is synchronously transmitted to the phased array radar module via an internal dedicated high-speed interface (such as PCIe or UDP). The signal processing unit in the phased array radar module, which is part of this equipment system, can measure the direction of arrival and arrival time of the mobile terminal's uplink signal to provide information for calculating the mobile terminal's coordinates.
[0033] The phased array radar module utilizes scheduling information obtained from the base station to precisely guide the signal reception process within the base station's coverage area. Optionally, in a "three-disconnection" scenario, for a specific lost target, step S4 above guides the reception process of mobile terminals within the coverage area using the scheduling information, including: in the time domain, data acquisition is initiated only within a specific subframe window where the target lost terminal is scheduled; in the frequency domain, signals are extracted only within the PRB bandwidth occupied by the target lost terminal; and in the user domain, the signal is identified using C-RNTI. The unique identification of the target signal via C-RNTI effectively separates concurrent signals from multiple users, significantly improving the signal-to-noise ratio. The guidance process in this embodiment effectively suppresses asynchronous interference and adjacent channel leakage, greatly improving the signal-to-noise ratio and acquisition reliability of weak target signals. The target lost terminal in this embodiment can be determined based on device information corresponding to the mobile terminal or contact information associated with the mobile terminal.
[0034] As mentioned in step S5 above, direction finding and ranging are performed on the target missing terminal based on signal data to obtain the azimuth and distance information corresponding to the target missing terminal. Specifically, direction finding of the target missing terminal includes: processing with a Multiple Signal Classification (MUSIC) super-resolution algorithm to calculate the direction of arrival (DOA) and obtain a high-precision azimuth angle estimate, which serves as the azimuth information corresponding to the target missing terminal.
[0035] In a selected embodiment of the present invention, high-precision direction finding based on the MUSIC algorithm is specifically performed as follows: (1) The preset phased array adopts a horizontal uniform linear array (ULA), with M array elements and d = / 2. For the preprocessed snapshot data x(t)∈CM×1 (t=1,2,…,L), construct the sample covariance matrix. The snapshot data refers to the vector composed of all the sampled values received by the phased array antenna at a certain moment from all sensors (array elements). The constructed sample covariance matrix is as follows:
[0036] The sample covariance matrix of the received signal, with dimensions M×M, dimensionless (or with units of...). ,like (expressed as voltage) : The received data vector of the t-th snapshot, with a dimension of M×1, and the unit is volts (V) or normalized complex amplitude (dimensionless). : The conjugate transpose of , with dimension 1×M; L: Valid snapshots, dimensionless, and a positive integer; t: Snapshot number, dimensionless, with a value range of t=1,2,…,L; M: The number of elements in the antenna array, dimensionless, and a positive integer; C: Complex field, indicating that the matrix elements are complex numbers; For example, suppose there is a 4-element uniform linear antenna array (i.e., 4 antenna elements) used to receive narrowband signals from the far field. During a certain time period, L=5 snapshots are collected.
[0037] Step 1: Construct the snapshot data matrix X. Assume the data from the 5 snapshots collected are as follows:
[0038] Each column is a snapshot, with a total of 5 columns → L=5L=5 Each row corresponds to the observation sequence of one antenna element. Step 2: Calculate the sample covariance matrix RxxRxx The sample covariance matrix is defined as follows:
[0039] in: XH is the hermitian transpose of X. If the data is a real number, then XH = XT The result is a 4×4 Hermitian matrix (symmetric positive semi-definite). Step 3: Calculation
[0040] First calculate XXT:
[0041] Calculate each element (using (1,1) and (1,2) as examples): (XXT)11=1.22+0.92+1.12+1.02+0.82=1.44+0.81+1.21+1.00+0.64=5.10 (XXT)12=1.2×0.5+0.9×0.6+1.1×0.4+1.0×0.7+0.8×0.5=0.6+0.54+0.44+0.7+0.4=2.68 (XXT)12=1.2×0.5+0.9×0.6+1.1×0.4+1.0×0.7+0.8×0.5=0.6+0.54+0.44+0.7+0.4=2.68 Continuing to calculate all elements, the result is approximately:
[0042] Then divide by L=5:
[0043] (2) Perform eigenvalue decomposition on the above sample variance matrix:
[0044] Where Un∈CM×(M-1) is the noise subspace.
[0045] The sample covariance matrix of the received signal, with dimensions M×M, and units of... (If the original signal is expressed as voltage) or dimensionless (if it has been normalized); U: Eigenvector matrix (also called unitary matrix), with dimensions M×M, and its column vectors are... The orthogonal eigenvectors are dimensionless; Λ: Eigenvalue diagonal matrix, with dimensions M×M, where the diagonal elements are the corresponding eigenvalues. Units and Same (i.e.) (or dimensionless); : The conjugate transpose of , with dimension M×M, is dimensionless; The eigenvector matrix corresponding to the signal subspace has a dimension of M×K (K is the number of sources) and is dimensionless; The eigenvalue diagonal matrix corresponding to the signal subspace has dimensions K×K, and the diagonal elements are the first K largest eigenvalues, with units of the same. ; The eigenvector matrix corresponding to the noise subspace has a dimension of M×(MK) and is composed of the last MK eigenvectors. It is dimensionless. : The eigenvalue diagonal matrix corresponding to the noise subspace, with dimensions (MK)×(MK), and the diagonal elements are approximately equal and close to the noise power, with units the same as Rxx; M: Total number of antenna elements, dimensionless; K: Number of target signal sources, dimensionless.
[0046] (3) For any assumed angle of incidence Its guiding vector is:
[0047] (4) Construct the MUSIC spatial spectral function:
[0048] The MUSIC spatial spectral function value represents the value under the assumed incident direction. The "pseudo-power" response is used for spectral peak search; this quantity is a dimensionless positive real number, and the larger the value, the higher the probability that there is a signal source in that direction; The assumed signal incident azimuth angle (Angle of Arrival) is taken with the array normal as the reference direction, and the unit is degrees (°) or radians (rad) (radians should be used uniformly in actual calculations). The steering vector, with a dimension of M×1, describes the relative complex phase distribution on each array element when a plane wave is incident from direction θ. It is dimensionless. The conjugate transpose of , with dimension 1×M, is dimensionless; The eigenvector matrix corresponding to the noise subspace is composed of the MK smallest eigenvectors after the eigenvalue decomposition of the covariance matrix, with a dimension of M×(MK) and is dimensionless. : The conjugate transpose of has a dimension of (MK)×M and is dimensionless; M: The total number of elements in the antenna array, dimensionless, a positive integer; K: Number of target signal sources (in this system, it is single-target localization, so K=1), dimensionless, positive integer.
[0049] (5) Calculate Pmusic on the discretized angular grid. And find the global maximum point:
[0050] Through Search for spectral peaks within the range to obtain high-precision azimuth estimates. This is used as the location information corresponding to the target lost terminal.
[0051] On the other hand, ranging the target lost terminal includes: acquiring the transmission time of the target lost terminal that triggers the transmission of an uplink signal recorded by the base station module, and sharing the transmission time with the phased array radar module through a hardware-level time synchronization interface; when the phased array radar module receives the uplink signal, it records the arrival time; and calculating the straight-line distance between the target lost terminal and the phased array radar module based on the transmission time, arrival time and speed of light, as the distance information corresponding to the target lost terminal.
[0052] This embodiment uses time-of-arrival (ToA) based on time synchronization to range the target lost terminal. The base station accurately records the expected transmission time of the uplink signal. The phased array radar module records the arrival time of the received signal. The two modules achieve nanosecond-level time synchronization through a hardware-level interface. The one-way signal propagation time is:
[0053] in Given a fixed system processing delay, the straight-line distance d from the target to the phased array radar module is calculated from the speed of light c.
[0054] Further, step S6 above, which calculates the absolute geographical latitude and longitude of the target lost terminal based on the azimuth and distance information, includes: converting the azimuth information into a true azimuth angle with geographic true north as the reference, using the azimuth information combined with the north offset angle calibrated during antenna installation; assuming the geographical coordinates of the phased array radar module are ( , If the target slant distance is d meters, then the target latitude and longitude ( , ), calculated using the forward spherical solution formula: R=6371000m
[0055] .
[0056] In other words, the obtained azimuth angle (which needs to be calibrated according to the northward offset angle of the antenna installation) and distance are combined with the known geographical latitude and longitude coordinates of the phased array radar antenna itself. Using spherical trigonometry or forward geodetic coordinate formulas, the absolute geographical latitude and longitude location of the missing terminal is calculated and output to the rescue command platform. Simultaneously, the system can bind the terminal's IMSI or C-RNTI identity information to its location, enabling precise search and rescue with traceable identity.
[0057] This invention also provides a base station-free large-area water rescue active search and positioning equipment system for performing the base station-free large-area water rescue active search and positioning equipment method described in the above embodiments, including a base station module and a phased array radar module.
[0058] like Figure 2 As shown, the base station-free large-area water rescue active search and positioning equipment system of this embodiment mainly includes a main control board, a base station module, a phased array radar module, and radio frequency components.
[0059] The main control board, as the core control unit, comprises multiple functional modules: a front-end / back-end communication module responsible for data interaction between the system and external devices; a heartbeat management module for monitoring system operation status and maintaining connection activity; a memory management module for allocating and reclaiming system resources; a thread management module for multi-task scheduling and concurrent control; a base station management module for base station-related configuration and protocol processing; and a phased array radar management module specifically for radar system parameter configuration and operating mode control. These modules collectively constitute the system's software control core, interacting with lower-level functional modules through a bidirectional data interface.
[0060] The base station module maintains bidirectional communication with the main control board and is connected to the first antenna via radio frequency components to achieve wireless signal transmission and reception. The phased array radar module is also bidirectionally connected to the main control board, but is directly connected to the second antenna to independently complete radar detection tasks. A bidirectional data exchange channel also exists between the base station module and the phased array radar module.
[0061] The radio frequency (RF) component serves as the signal conditioning unit of the base station module, performing functions such as digital-to-analog conversion, power amplification, and filtering. The RF component and radar module are each connected to an antenna, which helps avoid signal interference and allows the two systems to operate in parallel.
[0062] Application Case 1: Locating Missing Persons on a Large Lake To verify the system's performance in typical water rescue scenarios, a field test was conducted on a lake in a certain province. This scenario simulated a "triple disruption" environment—communication and power outages caused by extreme weather—where a tester carrying a mobile phone lost contact at a fixed point on the lake while in a small boat. Figures 3-4 .
[0063] System Deployment: The lightweight base station and phased array radar integrated equipment described in this embodiment of the invention are deployed at a fixed point on the lake shore, with geographical coordinates of (118.26108053242834°, 34.03845568737824°). The test terminal (IMSI: 460111129733658) is placed at another fixed location in the lake, with actual latitude and longitude of (118.22181702864252°, 34.07910923217247°), and the straight-line distance between the two points is approximately 5.795 kilometers.
[0064] Location process: After system startup, the self-built cell successfully induces the test terminal to connect and triggers it to transmit uplink SRS signals at maximum power. The phased array radar module performs guided reception based on the acquired scheduling information and performs MUSIC direction finding and ToA ranging. Subsequently, combined with the radar station coordinates and north offset angle, the geographical location of the target terminal is calculated.
[0065] Test Results: Ten independent positioning measurements were performed on the same target consecutively, and the results are shown in Table 1. The planar error of all positioning results was controlled within 13 meters, with the minimum error being 4.26 meters and the maximum error being 12.57 meters. The average positioning error was better than 8 meters, which is far better than the system design specification (≤50 meters).
[0066] Table 1
[0067] Application Case 2: Rescuing a Lost Elderly Person in a Certain City In May 2024, an elderly person went missing in a mountainous area. This system assisted relevant departments in successfully rescuing the person within 12 minutes. The device detected the latitude and longitude as (120.14503065182318, 28.616555733477956), and the final location of the person was (120.14507260655229, 28.616544552599947). Figure 5 As shown.
[0068] Application Case 3: Locating Missing Persons in Desert Areas To verify the system's performance in a vast, unobstructed environment with unique signal propagation characteristics, field tests were conducted in the Alashan Desert region of Inner Mongolia Autonomous Region. This scenario simulated the "three disruptions" condition where communication and transportation were completely cut off due to sandstorms or geological disasters.
[0069] The lightweight base station and phased array radar integrated device described in this embodiment of the invention was deployed at a fixed high point in the desert, with geographical coordinates of (98.092187, 42.020223). The test terminal (IMSI: 460023886545483) was placed at another fixed location approximately 576 meters away, with actual latitude and longitude of (98.0879380293719, 42.0161215953533).
[0070] In the open desert environment, the system rapidly acquired the test terminal's signal within its self-built cell. The base station module successfully induced the terminal to connect and triggered it to transmit an enhanced uplink reference signal. The phased array radar module used the acquired scheduling information for precise guidance and reception, and performed high-precision MUSIC direction finding and ToA ranging. Finally, combined with the known radar station coordinates, the geographical location of the target terminal was calculated. Test results show that, in 10 consecutive independent positioning measurements of the same target, all positioning results exhibited extremely high stability and accuracy. Thanks to the near-ideal line-of-sight (LOS) propagation conditions in the desert region and the system's strong anti-interference capabilities, the positioning error was effectively controlled. The test results are shown in Table 2.
[0071] Table 2
[0072] Figure 6 The image shows the equipment deployment. The horizontally mounted antenna is the radar antenna, the vertically mounted antenna is the base station antenna, and the pole-mounted antenna is the main unit.
[0073] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.
Claims
1. A method for active search and positioning equipment for large-area water rescue without base stations, characterized in that, include: Construct a local wireless coverage network that does not rely on the public network. The local wireless coverage network includes a base station module. The base station module is used to autonomously generate and broadcast cell signaling to form a local wireless communication cell in order to actively search for and capture mobile terminals that are powered on in the surrounding area. The base station module can access any disconnected mobile terminal and enhance the uplink signal of the mobile terminal. The communication scheduling information of the base station module is acquired and recorded in real time. The scheduling information is used to guide the reception process of mobile terminals within the coverage area to obtain signal data; Based on the signal data, the target lost terminal is subjected to direction finding and distance finding to obtain the azimuth information and distance information corresponding to the target lost terminal; The absolute geographical latitude and longitude of the target lost terminal is calculated based on the orientation and distance information.
2. The method according to claim 1, characterized in that, Accessing any disconnected mobile terminal based on the base station module and enhancing the uplink signal of the mobile terminal includes: Receive a random access request initiated by a lost mobile terminal, wherein the random access request is automatically initiated by the lost mobile terminal after detecting the signal of the wireless communication cell; In response to the random access request, a temporary link is established with the mobile terminal, and the mobile terminal is forced to continuously transmit a specific uplink reference signal at maximum transmit power through a valid Radio Resource Control (RRC) signaling or Transmit Power Control (TPC) command.
3. The method according to claim 1, characterized in that, The scheduling information includes: the cell radio network temporary identifier (C-RNTI), the uplink transmission subframe number, and the allocated physical resource block (RB).
4. The method according to claim 1, characterized in that, Guiding the reception process of mobile terminals within the coverage area using the scheduling information includes: In the time domain, data acquisition is only initiated within a specific subframe window where the target disconnected terminal is scheduled. In the frequency domain, only the signal within the PRB bandwidth occupied by the target lost terminal is extracted; In the user domain, signals are identified using C-RNTI.
5. The method according to claim 1, characterized in that, Direction finding of the target lost terminal includes: The direction of arrival (DOA) of the signal is calculated using the MUSIC super-resolution algorithm for multiple signal classification, and the estimated azimuth angle is obtained as the azimuth information corresponding to the target lost terminal.
6. The method according to claim 5, characterized in that, Ranging the target lost terminal includes: The base station module records the transmission time that triggers the target disconnected terminal to send an uplink signal, and shares the time with the phased array radar module through a hardware-level time synchronization interface; When the phased array radar module receives the uplink signal, it records the arrival time; based on the transmission time, arrival time and the speed of light, it calculates the straight-line distance between the target lost terminal and the phased array radar module, which is used as the distance information corresponding to the target lost terminal.
7. The method according to claim 6, characterized in that, Calculating the absolute geographical latitude and longitude of the target missing terminal based on the location and distance information includes: The azimuth information is used in conjunction with the north offset angle calibrated during antenna installation to convert it into a true azimuth angle based on geographic true north. Let the geographical coordinates of the phased array radar module be ( , If the target slant distance is d meters, then the target latitude and longitude ( , ), calculated using the forward spherical solution formula: ,R=6371000m, ， 。 8. A base station-free large-area water rescue active search and positioning equipment system for performing the base station-free large-area water rescue active search and positioning equipment method according to any one of claims 1 to 7, the system having a local wireless coverage network that does not rely on a public network, the local wireless coverage network including a base station module and a phased array radar module.