A large underground cavern group personnel positioning system and method based on a 5G communication network

Abstract

A personnel positioning system and method for a large underground cavern complex based on a 5G communication network is disclosed. The system includes: a 5G communication network module transmitting the unique NR-PCI code and antenna deployment information of each base station to a GIS information system module; the GIS information system module providing an indoor geographic database containing the binding relationship between NR-PCI codes and geographic locations to a positioning engine module; the positioning engine module calculating the location of the user equipment based on the measurement data, NR-PCI codes, and GIS geographic information reported by the user equipment, and sending the positioning result to a data management server module; the data management server module storing the positioning result, personnel trajectory, and system configuration data, and supporting access by upper-layer applications; and the user equipment accessing the 5G network, collecting positioning measurements such as reference signal received power, signal arrival time, and signal arrival angle, and uploading the data to the positioning engine module to report its own location. This system addresses the problems of insufficient positioning accuracy, reliance on additional base stations, and poor adaptability in existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of positioning technology, and specifically relates to a personnel positioning system and method for a large underground cavern complex based on a 5G communication network. Background Technology

[0002] Large underground cavern complexes (such as those in hydropower stations) are crucial infrastructure for energy production, transportation hubs, and other fields. Their complex internal structures, numerous interconnected caverns, and severe signal attenuation pose extremely high demands on personnel management and emergency response. Traditional hydropower station communication relies primarily on dedicated OPGW optical transmission networks and a wireless network coverage model combining cellular mobile networks and WiFi. However, this coverage method has a small single-point coverage area, requires a large number of devices, and incurs high long-term maintenance costs. Furthermore, with the rapid development of communication technology, the increasing demand for wireless communication, and the growing requirements for network security management, traditional communication infrastructure can no longer meet the needs for personnel positioning and safety monitoring within underground cavern complexes.

[0003] In existing large underground cavern complexes, GPS and BeiDou positioning suffer from severe signal blockage, rendering them ineffective. WiFi positioning has low accuracy and limited coverage. UWB positioning offers higher accuracy but requires extensive deployment of additional base stations, resulting in high costs and unsuitability for existing underground cavern complexes. To meet the regular communication needs within the production areas of large underground cavern complexes, 5G communication networks are typically constructed to provide mobile network signal coverage. While 5G networks offer high bandwidth and low latency, and the 3GPP protocol has incorporated positioning technology into 5G networks, existing 5G mobile signal coverage areas require additional base stations for basic positioning. Therefore, implementing 5G positioning technology in large underground cavern complexes presents the following fundamental challenges: 1. The underground cavern complex has a complex structure and the base stations are deployed in a dispersed manner. The signal coverage of omnidirectional antennas and unidirectional antennas is inconsistent, resulting in a large positioning error of a single base station, which makes it difficult to meet industrial-grade positioning standards. 2. The superposition of multiple caverns limits the application of dense 5G networking and antenna array technology, making it impossible to achieve accurate three-dimensional positioning; 3. Existing 5G positioning technology does not take into account the geographical characteristics of underground cavern complexes. Furthermore, the numerous devices within these complexes generate strong electromagnetic interference, leading to significant discrepancies between the positioning results and the actual scene. Back-end personnel cannot determine the specific location, thus hindering management.

[0004] Therefore, there is an urgent need for a personnel positioning technology that does not require additional positioning base stations, has high positioning accuracy, and is suitable for large underground cavern environments. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a personnel positioning system and method for large underground cavern groups based on 5G communication network, which solves the problems of insufficient positioning accuracy, reliance on additional base stations, and poor adaptability in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A personnel positioning system for a large underground cavern complex based on a 5G communication network. The system includes a 5G communication network module, a GIS information system module, a positioning engine module, a data management server module, and a user equipment (UE). The user equipment (UE) accesses the 5G communication network module via a wireless link and measures and uploads the reference signal received power (RSRP), time of arrival (TDOA), and angle of arrival (AOA) to the positioning engine module in real time. The 5G communication network module assigns a unique NR-PCI code to each antenna under the base station and binds the code to the standard coverage range of the antenna, which is then synchronously transmitted to the GIS information system module. The GIS information system module provides the positioning engine module with an indoor geographic database containing NR-PCI codes and geographic location binding relationships; The positioning engine module calculates the location of the user equipment (UE) based on the measurement data, NR-PCI code and GIS geographic information reported by the user equipment (UE), and sends the positioning result to the data management server module; The data management server module stores location results, personnel trajectories, and system configuration data, and supports access by upper-layer applications. Among them, each module communicates with each other through wired or wireless networks, forming an integrated closed-loop positioning architecture of "sensing-modeling-computing-storage-application". The functions of each module are as follows: User equipment (UE) is used to access 5G network base stations to obtain signal services, and also serves as a source of signal transmission and reception.

[0007] The 5G communication network module is used to deploy 5G signal coverage in large underground cavern complexes, provide communication and positioning interaction signal sources for user equipment (UE), and assign a unique NR-PCI code to each antenna; and bind the NR-PCI code to the base station, which records the received signals.

[0008] The GIS information system module is used to construct a real-scene geographic database of underground cavern groups, accurately bind NR-PCI codes with antenna physical locations and antenna coverage areas, synchronously label the precise location information of base stations, and form a multi-layer spatial mapping model; The positioning engine module is used to receive the signal source fed back by the 5G communication network module, synchronously call the data of the GIS information system module, combine the NR-PCI code to query the GIS geographic information, determine the signal coverage scene where the user equipment (UE) is located, and call the corresponding positioning algorithm to calculate the real-time location of the user equipment (UE). The data management server module is used to centrally store GIS data, base station configurations, positioning results and personnel trajectories, and supports trajectory playback, electronic fence alarms and emergency command. As a preferred embodiment, the 5G communication network module includes a baseband processing unit (BBU), multiple remote radio units (RRUs), a feeder, and an antenna; The baseband processing unit (BBU) is connected to each radio remote unit (RRU) via optical fiber and is responsible for baseband signal processing and resource scheduling. Each radio remote unit (RRU) is connected to at least one antenna via a feeder. The antennas include omnidirectional ceiling antennas and unidirectional directional antennas. Different antennas need to be deployed for coding assignment depending on the type of cavern group. Each antenna corresponds to an independent cell and is assigned a unique NR-PCI code; The deployment methods for 5G communication network modules include: a remote deployment mode of baseband processing unit (BBU) + radio remote unit (RRU) + high-power long-distance antenna in short and low tunnels; and a local coverage mode of centralized control of baseband processing unit (BBU), distributed deployment of radio remote unit (RRU), and local installation of antennas in large caves.

[0009] As a preferred embodiment, the GIS information system module includes a geographic data acquisition unit, a spatial modeling unit, and an NR-PCI binding unit; The geographic data acquisition unit is used to obtain the three-dimensional spatial structure, channel topology, coordinates of key facilities, and installation locations of base stations and antennas of the underground cavern complex; The spatial modeling unit constructs a realistic 3D geographic model containing caverns, passages, and equipment rooms based on the collected data, and labels the spatial attributes of each area; The NR-PCI binding unit maps the NR-PCI code of each antenna to its physical installation coordinates, orientation, and coverage area, forming a "NR-PCI-location-coverage area" triple database, which is then output to the positioning engine module.

[0010] As a preferred embodiment, the positioning engine module includes a scene recognition unit, an algorithm scheduling unit, and a position calculation unit; The scene recognition unit receives NR-PCI encoding and measurement data reported by the user equipment (UE), queries the coverage model in the GIS information system module, and determines whether the user equipment (UE) is currently in a single base station coverage scene, a multi-base station intersection coverage scene, or a cave / outdoor transition scene. Based on the identification results, the algorithm scheduling unit calls the corresponding positioning algorithm from the pre-set algorithm library: in the single base station scenario, the power-distance model based on RSRP is called; in the multi base station scenario, the geometric positioning algorithm based on TDOA or AOA is called; and in the hole scenario, satellite positioning and 5G positioning data are fused. The location calculation unit executes the selected algorithm to calculate the three-dimensional coordinates of the user equipment (UE), and then encapsulates the results and sends them to the data management server module.

[0011] As a preferred embodiment, the data management server module includes a data storage unit, a trajectory management unit, and an emergency service unit; The data storage unit is used to persistently store GIS geographic database, base station configuration information, NR-PCI mapping table, historical location records and algorithm parameters; The trajectory management unit records and visualizes personnel movement trajectories in real time, and supports trajectory playback and statistical analysis by time, region, and personnel ID. The emergency service unit configures electronic fence rules, triggers an alarm when a user equipment (UE) enters or leaves a preset danger zone, and generates the optimal evacuation route and pushes it to the user equipment (UE) or command center in an emergency.

[0012] As a preferred embodiment, the user equipment (UE) includes a 5G communication unit, a positioning and measurement unit, and a data reporting unit; The 5G communication unit is used to search for and access available cells in the 5G communication network module and obtain the NR-PCI code of the serving cell; The positioning measurement unit measures the reference signal received power (RSRP), time of arrival (TDOA), and angle of arrival (AOA) of the serving cell and neighboring cells in real time. The data reporting unit packages NR-PCI encoding, RSRP, TDOA, and AOA into a location request message, and sends it to the positioning engine module periodically or event-triggered through the 5G uplink channel.

[0013] The positioning method of this system includes the following steps: S1: Construct a 5G communication network for a large underground cavern complex, complete the deployment of baseband processing units, radio frequency remote units, feeders and antennas, and assign a unique NR-PCI code to the antenna of each base station in the large cavern complex; S2: Establish a GIS information system, collect real-scene geographic data of underground cavern groups, bind NR-PCI codes with the geographical locations of antennas and base stations, form a three-dimensional multi-dimensional geographic information database of NR-PCI-location-coverage area, and mark the standard signal coverage range according to antenna type to form an indoor positioning geographic database. S3: When a user equipment accesses a 5G communication network, its antenna receives a signal from the user equipment and simultaneously uploads data such as the reference signal received power, signal arrival time, and signal arrival angle of its location to the base station. The base station then collects the data and uploads it to the positioning engine module. S4: The positioning engine module first queries the GIS information system module based on the NR-PCI code uploaded by the user equipment to determine the approximate location of the base station and antenna currently accessed by the user equipment, and to determine the signal coverage scenario in which the user equipment is located. S5: Select the corresponding positioning algorithm to calculate the location of the user equipment based on different signal coverage scenarios; S6: The positioning engine module uploads the calculated user device location data to the data management server module for storage, and updates the personnel positioning trajectory at the same time.

[0014] S7: The background system retrieves the real-time location of personnel according to the corresponding application requirements, and performs emergency command, personnel supervision or signal tracking to ensure personnel safety.

[0015] Specifically, the calculation process of the single-base station positioning algorithm in step S5 is as follows: The formula relating received signal power to distance is: ; in The received signal power (i.e., RSRP). The base station signal transmission power, As a propagation factor, It is a constant related to the signal propagation frequency and antenna characteristics. The distance between the user equipment (UE) and the antenna; Taking the logarithm of both sides of the above formula, we get:

[0016] According to user equipment (UE) measurements Values, substitute them into the formula to solve. By combining the geographical location of the base station and the antenna coverage area in the GIS information system, the specific location of the user equipment (UE) within the coverage area is determined.

[0017] Specifically, the calculation process of the multi-base station positioning algorithm in step S5 is as follows: If the time-of-arrival (TOA) method is used for localization, let the coordinates of the antenna be respectively... The coordinates of the user equipment are The distances from the user equipment to each antenna are as follows: Then the following condition is met:

[0018]

[0019] make The above equation then transforms into The coordinates of the UE can be obtained using the determinant and the least squares method. If the signal arrival angle positioning method is used, let the coordinates of the user equipment be... The coordinates of the antenna are respectively The angles at which the uplink signal arrives at each base station are respectively ... Then the following condition is met:

[0020]

[0021] The coordinates of the user equipment can also be obtained by solving this system of equations using the least squares method. If a hybrid positioning method combining signal arrival time and signal arrival angle is used, the calculation results of the two algorithms mentioned above can be combined to obtain the precise coordinates of the user equipment.

[0022] Specifically, this method is applicable to personnel management, emergency rescue, and trajectory monitoring of large underground cavern complexes such as hydropower stations, subways, and mines, and its positioning accuracy meets industrial-grade positioning standards.

[0023] The present invention can achieve the following beneficial effects: 1. This invention does not require additional positioning base stations, but utilizes the existing 5G communication network for positioning, reducing deployment costs and modification difficulties, and is suitable for existing large underground cavern complexes; 2. This invention combines a GIS information system and an NR-PCI coding binding mechanism to accurately associate antenna coding, base stations, and geographical locations, thereby narrowing the positioning range and improving positioning accuracy; 3. This invention designs corresponding positioning algorithms for different signal coverage scenarios. In single-base station scenarios, positioning is achieved based on the relationship between signal power and distance. In multi-base station scenarios, TDOA, AOA, or hybrid algorithms are used. In cave entrance / outdoor scenarios, satellite positioning is combined to achieve seamless positioning in all scenarios. 4. The positioning accuracy of this invention meets industrial-grade standards and can be used for personnel management, emergency rescue, and trajectory monitoring in large underground cavern complexes, thereby improving the safety management level of underground cavern complexes. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 is a diagram of the 5G underground cavern group wireless network coverage architecture in this invention; Figure 2 is a diagram of the 3GPP 5G positioning technology architecture in this invention; Figure 3 is a diagram of the overall architecture of the positioning system in this invention; Figure 4 is a schematic diagram of the single base station positioning principle in this invention; Figure 5 is a schematic diagram of the multi-base station and TDOA / AOA positioning principle of the present invention; Figure 6 is a flowchart of the positioning method in this invention; Figure 7 is a simplified schematic diagram of the three-dimensional geographic model of the GIS information system in this invention. Detailed Implementation

[0025] Example 1 A personnel positioning system for a large underground cavern complex based on a 5G communication network includes a 5G communication network module, a GIS information system module, a positioning engine module, a data management server module, and user equipment. These modules work together to achieve precise personnel positioning in the underground cavern complex environment.

[0026] The 5G communication network module consists of a baseband processing unit, multiple radio frequency (RF) remote units, feeders, and antennas. The baseband processing unit is connected to each RF remote unit via optical fiber and is responsible for baseband signal processing and resource scheduling. Each RF remote unit is connected to at least one antenna via a feeder; the antennas include omnidirectional ceiling-mounted antennas and unidirectional directional antennas, with different deployment types selected based on the cavern structure. Each antenna corresponds to an independent cell and is assigned a unique NR-PCI code. In short, low-ceilinged tunnels, the system adopts a remote deployment mode of baseband processing unit + RF remote units + high-power long-distance antennas; in large caverns, a local coverage mode is adopted with centralized control of the baseband processing unit, distributed deployment of RF remote units, and antennas installed nearby. This flexible deployment method can adapt to the complex and varied spatial structure of underground cavern groups, ensuring the continuity and stability of signal coverage.

[0027] The GIS information system module includes a geographic data acquisition unit, a spatial modeling unit, and an NR-PCI binding unit. The geographic data acquisition unit obtains the three-dimensional spatial structure, passage topology, coordinates of key facilities, and antenna installation locations of the underground cavern complex. The spatial modeling unit constructs a realistic three-dimensional geographic model containing caverns, passages, and equipment spaces based on the acquired data, and labels the spatial attributes of each area. The NR-PCI binding unit maps the NR-PCI code of each base station antenna to its physical installation coordinates, orientation, and coverage area, forming an "NR-PCI—location—coverage area" triple database, which is then output to the positioning engine module. In this way, the system establishes a precise correspondence between virtual geographic information and physical space, providing a geographic reference basis for subsequent positioning calculations.

[0028] The positioning engine module includes a scene recognition unit, an algorithm scheduling unit, and a location calculation unit. The scene recognition unit receives NR-PCI encoding and measurement data reported by the user equipment, queries the coverage model in the GIS information system module, and determines whether the user equipment is currently in a single-base station coverage scenario, a multi-base station overlapping coverage scenario, or a tunnel / outdoor transition scenario. Based on the recognition result, the algorithm scheduling unit calls the corresponding positioning algorithm from a pre-set algorithm library: for single-base station scenarios, it calls a power-distance model based on the reference signal received power; for multi-base station scenarios, it calls a geometric positioning algorithm based on signal arrival time or signal arrival angle; and for tunnel scenarios, it fuses satellite positioning and 5G positioning data. The location calculation unit executes the selected algorithm, calculates the three-dimensional coordinates of the user equipment, and encapsulates the result before sending it to the data management server module. This scene-adaptive algorithm scheduling mechanism significantly improves the positioning accuracy and stability of the system in different environments.

[0029] The data management server module includes a data storage unit, a trajectory management unit, and an emergency service unit. The data storage unit persistently stores the GIS geographic database, base station configuration information, NR-PCI mapping table, historical location records, and algorithm parameters. The trajectory management unit records and visualizes personnel movement trajectories in real time, supporting trajectory playback and statistical analysis by time, region, and personnel ID. The emergency service unit configures electronic fence rules, triggering alarms when user devices enter or leave preset danger zones, and generating optimal evacuation routes that are pushed to user devices or the command center in emergencies. These functions enable the system to not only achieve basic personnel positioning but also provide safety monitoring and emergency management support.

[0030] The user equipment includes a 5G communication unit, a positioning and measurement unit, and a data reporting unit. The 5G communication unit searches for and accesses available cells in the 5G communication network module, obtaining the NR-PCI code of the serving cell. The positioning and measurement unit measures the reference signal received power, signal arrival time, and signal arrival angle of the serving cell and neighboring cells in real time. The data reporting unit packages the NR-PCI code, reference signal received power, signal arrival time, and signal arrival angle into a positioning request message, which is periodically or event-triggered and sent to the positioning engine module via the 5G uplink channel. The user equipment can be a dedicated positioning terminal, or a smartphone or wearable device with integrated positioning functionality, making it convenient for staff to carry.

[0031] During system operation, user equipment connects to the 5G communication network module via a wireless link, and measures and uploads reference signal received power, signal arrival time, and signal arrival angle to the positioning engine module in real time. The 5G communication network module transmits the unique NR-PCI code of each base station and its antenna deployment information to the GIS information system module. The GIS information system module provides the positioning engine module with an indoor geographic database containing the binding relationship between NR-PCI codes and geographic locations. The positioning engine module calculates the location of the user equipment based on the measurement data, NR-PCI codes, and GIS geographic information reported by the user equipment, and sends the positioning results to the data management server module. The data management server module stores the positioning results, personnel trajectories, and system configuration data, and supports access by upper-layer applications. Through this closed-loop workflow, the system can achieve real-time and accurate positioning of personnel in complex underground cavern environments, providing technical support for safety management and emergency rescue.

[0032] Example 2 This embodiment provides a positioning method for a large underground cavern group personnel positioning system based on a 5G communication network. This method achieves accurate positioning of personnel in the underground cavern group environment by constructing a 5G communication network, establishing a GIS information system, and selecting an appropriate positioning algorithm.

[0033] The positioning method includes the following steps: S1: Construct a 5G communication network for a large underground cavern complex, complete the deployment of baseband processing units, radio frequency remote units, feeders and antennas, and assign a unique NR-PCI code to the antenna of each base station in the large cavern complex; The 5G communication network module in this step is the same as that described in Embodiment 1, including a baseband processing unit, multiple radio frequency remote units, feeders, and antennas, and adopts the same deployment method.

[0034] S2: Establish a GIS information system, collect real-scene geographic data of underground cavern groups, bind NR-PCI codes with the geographical locations of antennas and base stations, form a three-dimensional multi-dimensional geographic information database of NR-PCI-location-coverage area, and mark the standard signal coverage range according to antenna type to form an indoor positioning geographic database. The GIS information system module in this step is the same as that described in Example 1, including a geographic data acquisition unit, a spatial modeling unit, and an NR-PCI binding unit, and performs the same functions.

[0035] S3: When a user equipment accesses a 5G communication network, its antenna receives a signal from the user equipment and simultaneously uploads data such as the reference signal received power, signal arrival time, and signal arrival angle of its location to the base station. The base station then collects the data and uploads it to the positioning engine module. The user equipment in this step is the same as that described in Embodiment 1, including a 5G communication unit, a positioning measurement unit, and a data reporting unit, and performs the same functions.

[0036] S4: The positioning engine module first queries the GIS information system module based on the NR-PCI code uploaded by the user equipment to determine the approximate location of the base station and antenna currently accessed by the user equipment, and to determine the signal coverage scenario in which the user equipment is located. The positioning engine module in this step is the same as that described in Embodiment 1, including a scene recognition unit, an algorithm scheduling unit, and a location calculation unit, and performs the same functions.

[0037] S5: Select the corresponding positioning algorithm to calculate the location of the user equipment based on different signal coverage scenarios; The calculation process of the single-base station positioning algorithm is as follows: The formula relating received signal power to distance is: ; in The received signal power, i.e., the reference signal received power, The base station signal transmission power, As a propagation factor, It is a constant related to the signal propagation frequency and antenna characteristics. The distance between the user equipment and the antenna; Taking the logarithm of both sides of the above formula, we get: ; Measurements based on the signal received by the antenna Values, substitute them into the formula to solve. It can calculate the basic distance from the user equipment to the antenna. By combining the NR-PCI coding in the GIS information system to determine the geographical location of the base station and the specific location of the antenna, the specific location of the user equipment within the coverage area can be deduced.

[0038] The calculation process of the multi-base station positioning algorithm is as follows: If the time-of-arrival (TOA) method is used for localization, let the coordinates of the antenna be respectively... The coordinates of the user equipment are The distances from the user equipment to each antenna are as follows: Then the following condition is met: ; ; make The above equation then transforms into The coordinates of the UE can be obtained using the determinant and the least squares method. If the signal arrival angle positioning method is used, let the coordinates of the user equipment be... The coordinates of the antenna are respectively The angles at which the uplink signal arrives at each base station are respectively Then the following condition is met:

[0039]

[0040] The coordinates of the user equipment can also be obtained by solving this system of equations using the least squares method. If a hybrid positioning method combining signal arrival time and signal arrival angle is used, the calculation results of the two algorithms mentioned above can be combined to obtain the precise coordinates of the user equipment.

[0041] S6: The positioning engine module uploads the calculated user device location data to the data management server module for storage, and updates the personnel positioning trajectory at the same time.

[0042] The data management server module in this step is the same as that described in Embodiment 1, including a data storage unit, a trajectory management unit, and an emergency service unit, and performs the same functions.

[0043] S7: The background system retrieves the real-time location of personnel according to the corresponding application requirements, and performs emergency command, personnel supervision or signal tracking to ensure personnel safety.

[0044] In this step, the system can retrieve real-time location information of personnel through the interface provided by the data management server module, according to different application scenario requirements. In emergency command scenarios, the system can quickly locate the position of trapped personnel and provide accurate navigation for rescuers; in personnel monitoring scenarios, the system can monitor the location distribution of staff in real time to ensure that personnel do not enter dangerous areas; in signal tracking scenarios, the system can record and analyze personnel movement trajectories and identify abnormal behavior patterns.

[0045] This method is applicable to personnel management, emergency rescue, and trajectory monitoring in large underground cavern complexes such as hydropower stations, subways, and mines, with positioning accuracy meeting industrial-grade positioning standards. Leveraging the high bandwidth and low latency characteristics of 5G networks, combined with the complementary advantages of multiple positioning algorithms, this method enables real-time and accurate personnel positioning in complex underground environments, providing strong technical support for the safety management of underground engineering projects.

[0046] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A personnel positioning system for a large underground cavern complex based on a 5G communication network, characterized in that, The system includes a 5G communication network module, a GIS information system module, a positioning engine module, a data management server module, and user equipment. The user equipment connects to the 5G communication network module via a wireless link and measures and uploads the reference signal received power, signal arrival time, and signal arrival angle to the positioning engine module in real time. The 5G communication network module transmits the unique NR-PCI code of each base station and its antenna deployment information to the GIS information system module; The GIS information system module provides the positioning engine module with an indoor geographic database containing NR-PCI codes and geographic location binding relationships; The positioning engine module calculates the location of the user equipment based on the measurement data, NR-PCI code and GIS geographic information reported by the user equipment, and sends the positioning results to the data management server module. The data management server module stores location results, personnel trajectories, and system configuration data, and supports access by upper-layer applications. User equipment is used to access the 5G network, collect positioning measurements such as reference signal received power, signal arrival time, and signal arrival angle, and upload the data to the positioning engine module to realize its own location reporting.

2. The personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 1, characterized in that, The 5G communication network module includes a baseband processing unit, multiple radio frequency remote units, feeders, and antennas; The baseband processing unit is connected to each radio frequency remote unit via optical fiber and is responsible for baseband signal processing and resource scheduling. Each radio frequency remote unit is connected to at least one antenna via a feeder. The antennas include omnidirectional ceiling antennas and unidirectional directional antennas, and the deployment type is selected according to the cave structure. Each antenna corresponds to an independent cell and is assigned a unique NR-PCI code; The deployment methods for 5G communication network modules include: a remote deployment mode of baseband processing unit + radio frequency remote unit + high-power long-distance antenna in short and low tunnels, and a local coverage mode of centralized control of baseband processing unit, distributed deployment of radio frequency remote unit, and local installation of antenna in large caves.

3. The personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 1, characterized in that, The GIS information system module includes a geographic data acquisition unit, a spatial modeling unit, and an NR-PCI binding unit; The geographic data acquisition unit is used to obtain the three-dimensional spatial structure, passage topology, coordinates of key facilities, and antenna installation locations of the underground cavern complex. The spatial modeling unit constructs a realistic 3D geographic model containing caverns, passages, and equipment rooms based on the collected data, and labels the spatial attributes of each area; The NR-PCI binding unit maps the NR-PCI code of each base station antenna to its physical installation coordinates, orientation, and coverage area, forming a "NR-PCI-location-coverage area" triple database, which is then output to the positioning engine module.

4. The personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 1, characterized in that, The positioning engine module includes a scene recognition unit, an algorithm scheduling unit, and a location calculation unit; The scene recognition unit receives NR-PCI encoding and measurement data reported by the user equipment, queries the coverage model in the GIS information system module, and determines whether the user equipment is currently in a single base station coverage scene, a multi-base station intersection coverage scene, or a tunnel / outdoor transition scene. Based on the identification results, the algorithm scheduling unit calls the corresponding positioning algorithm from the pre-set algorithm library: in the single base station scenario, the power-distance model based on the reference signal received power is called; in the multi base station scenario, the geometric positioning algorithm based on the signal arrival time or signal arrival angle is called; and in the cave entrance scenario, satellite positioning and 5G positioning data are fused. The location calculation unit executes the selected algorithm, calculates the three-dimensional coordinates of the user equipment, and encapsulates the results before sending them to the data management server module.

5. The personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 1, characterized in that, The data management server module includes a data storage unit, a trajectory management unit, and an emergency service unit; The data storage unit is used to persistently store GIS geographic database, base station configuration information, NR-PCI mapping table, historical location records and algorithm parameters; The trajectory management unit records and visualizes personnel movement trajectories in real time, and supports trajectory playback and statistical analysis by time, region, and personnel ID. The emergency service unit is configured with electronic fence rules. When a user device enters or leaves a preset danger zone, an alarm is triggered, and in an emergency, the optimal evacuation route is generated and pushed to the user device or command center.

6. The personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 1, characterized in that, User equipment includes a 5G communication unit, a positioning and measurement unit, and a data reporting unit; The 5G communication unit is used to search for and access available cells in the 5G communication network module and obtain the NR-PCI code of the serving cell; The positioning measurement unit measures the reference signal received power, signal arrival time, and signal arrival angle of the serving cell and neighboring cells in real time. The data reporting unit packages the NR-PCI encoding, reference signal received power, signal arrival time, and signal arrival angle into a positioning request message, and sends it to the positioning engine module periodically or event-triggered through the 5G uplink channel.

7. A positioning method for a personnel positioning system based on a 5G communication network for a large underground cavern complex, as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Construct a 5G communication network for a large underground cavern complex, complete the deployment of baseband processing units, radio frequency remote units, feeders and antennas, and assign a unique NR-PCI code to the antenna of each base station in the large cavern complex; S2: Establish a GIS information system, collect real-scene geographic data of underground cavern groups, bind NR-PCI codes with the geographical locations of antennas and base stations, form a three-dimensional multi-dimensional geographic information database of NR-PCI-location-coverage area, and mark the standard signal coverage range according to antenna type to form an indoor positioning geographic database. S3: When a user equipment accesses a 5G communication network, its antenna receives a signal from the user equipment and simultaneously uploads data such as the reference signal received power, signal arrival time, and signal arrival angle of its location to the base station. The base station then collects the data and uploads it to the positioning engine module. S4: The positioning engine module first queries the GIS information system module based on the NR-PCI code uploaded by the user equipment to determine the approximate location of the base station and antenna currently accessed by the user equipment, and to determine the signal coverage scenario in which the user equipment is located. S5: Select the corresponding positioning algorithm to calculate the location of the user equipment based on different signal coverage scenarios; S6: The positioning engine module uploads the calculated user device location data to the data management server module for storage, and updates the personnel positioning trajectory at the same time; S7: The background system retrieves the real-time location of personnel according to the corresponding application requirements, and performs emergency command, personnel supervision or signal tracking to ensure personnel safety.

8. A personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 7, characterized in that, The calculation process of the single-base station positioning algorithm in step S5 is as follows: The formula relating received signal power to distance is: ； in The received signal power, i.e., the reference signal received power, The base station signal transmission power, As a propagation factor, It is a constant related to the signal propagation frequency and antenna characteristics. The distance between the user equipment and the antenna; Taking the logarithm of both sides of the above formula, we get: ； Measurements based on the signal received by the antenna Values, substitute them into the formula to solve. It can calculate the basic distance from the user equipment to the antenna. By combining the NR-PCI coding in the GIS information system to determine the geographical location of the base station and the specific location of the antenna, the specific location of the user equipment within the coverage area can be deduced.

9. A personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 7, characterized in that, The calculation process of the multi-base station positioning algorithm in step S5 is as follows: If the time-of-arrival (TOA) method is used for localization, let the coordinates of the antenna be respectively... The coordinates of the user equipment are The distances from the user equipment to each antenna are as follows: Then the following conditions are met: ； ； make The above equation then transforms into The coordinates of the UE can be obtained using the determinant and the least squares method. If the signal arrival angle positioning method is used, let the coordinates of the user equipment be... The coordinates of the antenna are respectively The angles at which the uplink signal arrives at each base station are respectively ... Then the following conditions are met: ； ； The coordinates of the user equipment can also be obtained by solving this system of equations using the least squares method. If a hybrid positioning method combining signal arrival time and signal arrival angle is used, the calculation results of the two algorithms mentioned above can be combined to obtain the precise coordinates of the user equipment.

10. A personnel positioning system for a large underground cavern complex based on a 5G communication network according to claim 7, characterized in that, This method is applicable to personnel management, emergency rescue, and trajectory monitoring in large underground cavern complexes such as hydropower stations, subways, and mines, and its positioning accuracy meets industrial-grade positioning standards.

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