Ad hoc network cluster system for mine signal blind area
Through the relay devices and portable terminals in the self-organizing network cluster system, using the LoRa single channel and Mesh protocol, stable multi-person speech communication and rapid post-disaster recovery communication are achieved in the underground coal mine environment, solving the problem of unstable communication in the coal mine and meeting the needs of multi-person speech and post-disaster rescue.
Patent Information
- Application Number
- CN202511226906.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-29
- Publication Date
- 2025-10-17
AI Technical Summary
In underground coal mine working environments, existing wireless communication technologies suffer from severe signal attenuation, enhanced multipath interference, and severe noise interference, resulting in unstable communication, difficulty in multiple-person conversations, and difficulty in restoring communications after disasters.
Adopting a self-organizing cluster system, the system uses relay devices and portable terminals set at intervals, and utilizes the LoRa single-channel link and Mesh protocol for communication. The relay devices adaptively adjust the radio frequency parameters to achieve multi-hop relay and full-duplex communication, support multiple people speaking, and quickly restore communication after a disaster.
It achieved stable multi-person speech communication in complex coal mine environments, reduced communication costs, and restored communication within 30 minutes after the disaster, supporting the smooth implementation of rescue work.
Smart Images
Figure CN120812531A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of coal mine communication, in particular to a mine signal blind area self-organizing network cluster system. BACKGROUND
[0002] In the underground operation of coal mines, it is necessary to keep the ground control center in communication with the underground operation personnel and related control points to realize real-time understanding of the underground operation situation and timely response to emergencies, so the stability and reliability of wireless signal transmission are of great significance to the safe operation of coal mines. The influence of the underground operation environment of coal mines on wireless signal transmission is relatively complex, mainly restricted by the following four factors: first, high shielding, due to the bending of underground tunnels and the dense metal equipment, leading to serious signal attenuation, so that the coverage radius of traditional wireless communication is less than 500 meters; second, high noise, the noise of equipment operation is more than 100 dB, which needs to be processed by noise reduction algorithm to ensure clear voice; third, stratum absorption effect, the rock or coal layer under the coal mine can enhance the attenuation of wireless signals; fourth, enhanced multipath interference, the irregular surface of the tunnel leads to signal time delay expansion reaching 100-300 ns (usually <50 ns in ground environment), and the metal support structure will cause standing wave effect, making the field strength of some points fluctuate more than 40 dB.
[0003] In view of the complex underground operation environment of coal mines, at present, the industry mainly adopts three ways of intercom, 5G private network and megaphone to realize the communication between the ground and underground and between the underground. Among them, the intercom adopts half-duplex mode, only supports one person to speak, and it is difficult to meet the needs of multiple people to speak; the 5G private network communication mode needs to deploy the core network, which increases the overall cost of communication; the megaphone only supports fixed device communication, and its wiring is complex, which is easy to be damaged when disaster occurs, thereby affecting the normal communication in the rescue work. SUMMARY
[0004] Therefore, it is necessary to provide a mine signal blind area self-organizing network cluster system which can support multiple people to speak, has low cost and can quickly restore communication after disaster.
[0005] A mine signal blind area self-organizing network cluster system is arranged in the underground environment of a coal mine, comprising:
[0006] a relay unit, the relay unit comprises a plurality of relay devices arranged at intervals, at least one relay device is connected with a ground node by wire or wireless to receive and transmit emergency signals, each relay device adaptively adjusts radio frequency parameters, adjacent relay devices are connected by LoRa single channel link and communicate by Mesh protocol; and
[0007] A terminal unit comprising a plurality of body terminals connected with its nearest or strongest signal relay device through LoRa single channel link; the body terminal enters transmission mode when collecting personnel voice signal, or enters receiving mode when not collecting personnel voice signal;
[0008] The relay device allocates channel and time slot for the body terminal when receiving random access request sent by the body terminal in transmission mode, and forwards personnel voice signal to adjacent relay device or sends in broadcast mode to body terminal in receiving mode; or the relay device forwards emergency signal to adjacent relay device or sends in broadcast mode to body terminal in receiving mode when receiving emergency signal.
[0009] In one of the embodiments, the relay device comprises a first master MCU, a first radio frequency transceiver connected with the first master MCU, a first explosion-proof battery connected with the first master MCU, a first charging interface connected with the first explosion-proof battery, a wired interface connected with the first master MCU, a first digital signal processor connected with the first master MCU, an earpiece connected with the first digital signal processor and used for collecting or outputting voice signal, and the first master MCU integrates LoRa baseband.
[0010] In one of the embodiments, the relay device further comprises a first power amplifier connected with the first radio frequency transceiver and a first antenna switch connected with the first master MCU.
[0011] In one of the embodiments, the body terminal comprises a second master MCU, a second radio frequency transceiver connected with the second master MCU, a second explosion-proof battery connected with the second master MCU, a second charging interface connected with the second explosion-proof battery, a second digital signal processor connected with the second master MCU, a headset connected with the second digital signal processor and used for outputting voice signal, a microphone assembly connected with the second digital signal processor and used for collecting voice signal, and the second master MCU integrates LoRa baseband.
[0012] In one of the embodiments, the headset is bone conduction headset; the microphone assembly comprises a main microphone close to user's mouth and used for collecting voice and noise, and a sub microphone away from user's mouth and used for collecting environmental noise; the second digital signal processor receives voice signal sent by the main microphone and the sub microphone, calculates noise field characteristics through digital noise reduction algorithm, and generates reverse sound wave to offset noise.
[0013] In one of the embodiments, the body device further comprises a second power amplifier connected with the second radio frequency transceiver and a second antenna switch connected with the second master MCU.
[0014] In one of the embodiments, the plurality of body terminals connected with the relay device form a subsystem, each of the subsystems occupies a 500ms time slot, each of the subsystems is cyclically polled, the ad-hoc network cluster system broadcasts in a full time period, and each of the body terminals receives in a time-sharing manner.
[0015] In one of the embodiments, the relay device dynamically adjusts the transmission power according to the RSSI.
[0016] In one of the embodiments, the length of the voice packet formed by the sound signal forwarded by the relay device is limited within 20ms.
[0017] In one of the embodiments, each of the relay devices periodically scans the frequency band to avoid occupied channels.
[0018] The ad-hoc network cluster system for the mine signal blind area according to the present application forms a centerless ad-hoc network through a plurality of relay devices and a plurality of body terminals, the relay device is based on the adaptive radio frequency and the mesh protocol, can realize the multi-hop relay, ensures that the communication distance meets the needs of the underground and ground communication, the relay devices are connected through the LoRa single channel link between the relay devices and the body devices, and the time division multiplexing is realized through the channel and time slot allocation, so that the full duplex communication capability can be obtained through the combination of the LoRa single channel and the time division multiplexing, which can support multiple people to talk and meet the needs of multiple people to talk, the use of the LoRa single channel can reduce the communication cost at the same time; the ad-hoc network architecture does not need a center base station, can be quickly deployed and has high reliability, can restore communication within 30 minutes after a disaster, and is beneficial to the effective development of rescue work. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 The topological graph of the ad-hoc network cluster system in one of the embodiments of the present application;
[0020] Figure 2 The logic block diagram of the ad-hoc network cluster system in one of the embodiments of the present application;
[0021] Figure 3 The distributed communication flow of the ad-hoc network cluster system in one of the embodiments of the present application;
[0022] Figure 4 The module connection diagram of the relay device in one of the embodiments of the present application;
[0023] Figure 5 The module connection diagram of the body terminal in one of the embodiments of the present application. DETAILED DESCRIPTION
[0024] For the above purposes, features and advantages of the present application to be more apparent, a detailed description of the specific embodiments of the present application is given below with reference to the accompanying drawings. In the following description, a number of specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different manners than those described herein, and it is understood that similar improvements can be made by those skilled in the art without departing from the scope of the present application, therefore the present application is not limited to the specific embodiments disclosed below.
[0025] Please refer to Figure 1 and Figure 2 The present application discloses a mine signal blind area self-organizing network cluster system which can support multiple people to speak, has low cost and can quickly restore communication after disaster, the self-organizing network cluster system is arranged in a coal mine underground environment, realizes communication between coal mine underground operating personnel and communication between coal mine underground and ground station, especially, can quickly restore communication after disaster in the underground to ensure the smooth development of rescue work. Specifically, the self-organizing network cluster system of the embodiment comprises a relay unit and a terminal unit, wherein the relay unit comprises a plurality of relay devices arranged at intervals, in the embodiment, the relay device is a repeater, its communication distance A in the coal mine underground is 150-200m, in other words, the distance between the relay devices arranged at intervals can be up to 200m. At least one relay device is connected with the ground node by wire or wireless to receive and transmit emergency signals, in the embodiment, the ground node can also be a relay device, the relay device as the ground node works in the conventional working area (above the well), it communicates with the relay device in the special working area (underground) to send emergency signals or other communication signals to the underground. Especially, the relay device as the ground node communicates with the relay device in the nearest special working area to listen to the voice information in the underground or send voice information to the underground. Each relay device adaptively adjusts the radio frequency parameters to make the relay device achieve the optimal communication effect in the current environment. Adjacent relay devices are connected by LoRa single channel link and communicate by Mesh protocol, in this way, the relay device can realize multi-hop relay by the adaptive radio frequency combined with the Mesh protocol to realize long distance communication. The terminal unit comprises a plurality of body terminals, the body terminal is connected with the nearest or the strongest signal relay device by LoRa single channel link; the body terminal enters the transmission mode when collecting personnel voice signals, or enters the receiving mode when not collecting personnel voice signals.
[0026] In this embodiment, in the case of using adaptive radio frequency, if the relay device finds that the current frequency band used has great interference, it can automatically switch to another clean frequency band for communication, realizing frequency adaptation (frequency hopping); when the distance between two relay devices is very close, the relay device automatically reduces the transmission power to save energy and reduce interference to other devices, and when the distance becomes farther or the number of obstacles increases, the relay device automatically increases the power to ensure the continuity of the link, realizing power adaptation; when the channel quality is good, high-order modulation (such as 256-QAM) is used to realize high-speed transmission; when the quality becomes poor, the relay device automatically switches to more robust low-order modulation (such as QPSK) to ensure connectivity by sacrificing speed, realizing rate adaptation; the relay device can also dynamically adjust the occupied spectrum width according to the amount of data to be transmitted and the channel conditions, realizing bandwidth adaptation. In this way, in multi-hop relay, adaptive radio frequency ensures that the link quality of "each hop" is optimal and stable, which can prevent link interruption, and this is also the physical basis for realizing reliable multi-hop relay. In multi-hop relay, the mesh protocol is used to determine where the data packet (in this embodiment, a voice packet) should jump to next. In the case of communication between adjacent relay devices through the mesh protocol, when the relay device is powered on, the relay device can automatically discover other relay devices around it and establish a connection relationship to form a mesh network, realizing automatic discovery and automatic networking. In addition, the mesh protocol can provide data through adaptive radio frequency to comprehensively consider factors such as link quality, channel load, error rate, and delay to continuously detect and calculate the optimal path to the target node. When a node (relay device) in the mesh network sends a fault, moves, or is subjected to strong interference (path interruption), the nodes (relay devices) around it can perceive this change and automatically and quickly recalculate the route to switch the data stream to other backup paths.
[0027] For example, in this embodiment, when the relay devices communicate with each other through the mesh protocol, if a relay device receives a request sent by a body terminal connected to it, the mesh protocol of the relay device starts to calculate the backhaul path, and the adaptive radio frequency module (a module for realizing adaptive adjustment of radio frequency parameters) of the relay device evaluates the link quality to adjacent nodes (relay devices) in real time and provides this information to the mesh protocol. The mesh protocol judges the link rate of different nodes according to this information and selects a transmission path. Subsequently, the radio frequency module of the relay device sends data packets to the nodes on the selected transmission path in sequence with optimized power and modulation mode, and the next node continues to determine the node to jump to next through its mesh protocol. When an external frequency band interferes with the frequency band of the mesh network, for example, when the interference increases sharply and the link quality drops sharply, the adaptive radio frequency module of each node (relay device) sends this situation to the mesh protocol, the mesh protocol responds instantly and recalculates the route, and performs path switching to realize real-time optimization of the path.
[0028] The relay device allocates a channel and a time slot for the body terminal when receiving a random access request sent by the body terminal in the transmitting mode, and forwards the personnel voice signal to the adjacent relay device or sends it to the body terminal in the receiving mode in a broadcast mode; or the relay device forwards the emergency signal to the adjacent relay device or sends it to the body terminal in the receiving mode in a broadcast mode when receiving the emergency signal. In the embodiment, the relay devices are connected through a LoRa single-channel link, the relay devices and the body terminals are connected through a LoRa single-channel link, and the relay device allocates a signal and a time slot for the body terminal by receiving a random access request sent by the body terminal. In this way, on a single LoRa radio frequency channel, a node can both send and receive data through time division multiplexing, thereby logically simulating full-duplex communication capability to meet the demand for multiple people to talk, while the cost of the LoRa single channel is relatively low, which is conducive to reducing communication costs. In addition, in the embodiment, the relay device allocates a channel and a time slot by receiving a random access request from the body terminal. In this way, the relay device filters and proposes a usable time slot for the body terminal based on local information, and informs the body terminal of the proposal through a response, and finally, the body terminal completes the final occupation by actually using and declaring the time slot, so that other nodes (including relay devices and body terminals) in the system perceive this new change. In this way, through such a way, the LoRa single channel is used and the full-duplex communication mode is simulated, and at the same time, in the absence of a central node, the self-organizing allocation of resources is achieved through cooperation between nodes, thereby ensuring the high resilience and survivability of the network.
[0029] It should be noted that in the embodiment, the priority of the emergency signal sent by the ground node to the underground relay device is higher than that of the voice signal transmitted between the relay devices and between the relay devices and the body terminals, that is, when the relay device receives the emergency signal from the ground and the voice signal from the body terminal in the well at the same time, the relay device preferentially forwards the emergency signal to respond to the disaster situation in time.
[0030] Please refer to Figures 1-5 , the relay device includes a first master control MCU (i.e. MCU in Figure 4 ), a first radio frequency transceiver (i.e. RF Transceiver in Figure 4 ) connected with the first master control MCU, a first explosion-proof battery (i.e. explosion-proof battery in Figure 4 ) connected with the first master control MCU, a first charging interface (i.e. USB / Type-C in Figure 4 ) connected with the first explosion-proof battery, a wired interface (i.e. wired interface in Figure 4a first digital signal processor (i.e. DSP in Figure 4 ) connected with the first master MCU, an earpiece (i.e. earpiece in Figure 4 ) connected with the first digital signal processor and used for collecting or outputting sound signals, and the first master MCU integrates a LoRa baseband. In this embodiment, the first master MCU is further provided with an adaptive radio frequency module for realizing adaptive adjustment of radio frequency parameters of the relay device. Further, the relay device further comprises a first power amplifier (i.e. RF-PA in Figure 4 ) connected with the first radio frequency transceiver and a first antenna switch (i.e. ON / OFF, SW KEY in Figure 4 ) connected with the first master MCU, and the first power amplifier adopts a chip with a model of SKY66421 or a chip with the same performance, which can support a maximum output of 20dBm. The relay device further comprises a first low noise amplifier (i.e. LNA in Figure 5The first radio frequency transceiver is connected to the first main control MCU through the SPI synchronous serial communication protocol. The first main control MCU is a chip with the model number STM32WLE5JC or a chip with the same performance. The first main control MCU is integrated with a LoRa baseband to meet the transmission of a single channel link of LoRa. The first main control MCU is connected to the first explosion-proof battery through the PWR signal. In this way, the power supply of the first explosion-proof battery to other high-risk circuits of the relay device is cut off through the PWR signal, physical isolation is achieved, and the safety of the relay device in use in the well is improved. The first charging interface is a USB interface or a Type-C interface, which provides a voltage of 3.3V or 1.8V to the first explosion-proof battery. The relay device further includes a first LED lamp electrically connected to the first charging interface. The first LED lamp is used to light up when charging at the first charging interface to display the charging status of the relay device. In the embodiment, the wired interface CAN-FD is connected to the first main control MCU through the SPI or UART. The relay devices can be connected through the first radio frequency transceiver for wireless communication or through the wired interface for wired connection. The first antenna switch is a chip with the model number SKY13370 or a chip with the same performance. The first antenna switch can support fast frequency band switching to meet the needs of users for communication in different frequency bands. Similarly, the first digital signal processor is connected to the first main control MCU through the SPI synchronous serial communication protocol. After the earpiece collects the sound signal, the analog signal is converted into a digital signal by an analog-to-digital converter (ADC) and sent to the first digital signal processor for further transmission to the first main control MCU, or a digital-to-analog converter (DAC) converts the digital signal of the first digital signal processor into an analog signal and sends it to the earpiece for playing. In this way, the relay device can answer or intercom through the earpiece. It works without dialing (equivalent to a personal terminal) when it is picked up. At this time, the relay device can be used as a ground node to send an emergency signal to the relay device in the well. In actual use, the relay device in the well can also cancel the first digital signal processor, the analog-to-digital converter, the digital-to-analog converter, and the earpiece, and only be used for signal transmission and processing.
[0031] The personal terminal includes a second main control MCU (i.e., the MCU in Figure 5 The second radio frequency transceiver (i.e., the RF Transceiver in Figure 5 The second explosion-proof battery (i.e., the battery in Figure 5a second charging interface (i.e. Figure 5 a USB / Type-C in the second explosion-proof battery), a second digital signal processor (i.e. Figure 5 a DSP in the second main control MCU), a headset (i.e. Figure 5 a bone conduction unit in the second digital signal processor) connected to the second digital signal processor and used for outputting sound signals, a microphone assembly (i.e. Figure 5 mic1, mic2…micn in the second digital signal processor) connected to the second digital signal processor and used for collecting sound signals, and the second main control MCU integrates a LoRa baseband. Further, the body device further includes a second power amplifier (i.e. Figure 5 RF-PA in the second radio frequency transceiver) connected to the second radio frequency transceiver and a second antenna switch (i.e. Figure 5 ON / OFF, V+KEY, V-KEY, SW KEY in the second main control MCU). The second power amplifier adopts a chip with a model number of SKY66421 or a chip with the same performance, which can support a maximum output of 20dBm. The body terminal further includes a second low noise amplifier (i.e. Time slotThe second radio frequency transceiver is connected to the second power amplifier or the second low noise amplifier, and realizes wireless connection between the body terminal and the relay device. The second radio frequency transceiver is a slave device, and is connected to the second master MCU as a master device through the SPI synchronous serial communication protocol to exchange data and commands. The second master MCU is a chip with the model number STM32WLE5JC or a chip with the same performance, and is integrated with a LoRa baseband to meet the transmission of a single channel link of LoRa. The second master MCU is connected to the second explosion-proof battery through the PWR signal, so that the power supply of the second explosion-proof battery to other high-risk circuits of the body terminal is cut off through the PWR signal, physical isolation is realized, and the safety of the body terminal in the underground use is improved. The second charging interface is a USB interface or a Type-C interface, which provides a voltage of 3.3V or 1.8V to the second explosion-proof battery. The body terminal further comprises a second LED lamp electrically connected to the second charging interface, which is used to light up when charging at the second charging interface to display the charging state of the body terminal. The second antenna switch is a chip with the model number SKY13370 or a chip with the same performance, which can support fast frequency band switching to meet the needs of users for communication in different frequency bands. Similarly, the second digital signal processor is connected to the second master MCU through the SPI synchronous serial communication protocol. After the microphone assembly collects the sound signal, the analog signal is converted into a digital signal by an analog-to-digital converter (ADC) and sent to the second digital signal processor, so as to be further sent to the second master MCU by the second digital signal processor, or a digital-to-analog converter (DAC) converts the digital signal of the second digital signal processor into an analog signal and sends it to the earphone to play, so as to meet the needs of the body terminal for answering and conversation.
[0032] In this embodiment, the earphone is a bone conduction earphone, which is not easily affected by high noise environment, and is particularly suitable for use in high noise environment such as coal mine, to ensure that the user hears clear voice information. The microphone assembly on the handheld terminal is used to collect the speech and sound received by the personnel. The microphone assembly includes a main microphone close to the user's mouth and used to collect voice and noise, and a secondary microphone away from the user's mouth and used to collect environmental noise; the second digital signal processor receives the sound signals sent by the main microphone and the secondary microphone, calculates the noise field characteristics through a digital noise reduction algorithm, and generates a reverse sound wave to offset the noise. In this embodiment, the number of main microphones and secondary microphones is at least one. When the handheld terminal is used, the main microphone is used to capture a mixed signal including clear voice of the user and environmental noise. Since the main microphone is close to the mouth, the strength of the voice signal picked up by the main microphone is much higher than that of the secondary microphone. The secondary microphone is used to capture pure environmental noise. Since it is away from the mouth, the energy of the user's voice transmitted here has been greatly attenuated, so the signal collected by it can be considered as a "noise reference signal". In this way, the analog signals collected by the main microphone and the secondary microphone are converted by an analog-to-digital converter (ADC) and further transmitted to the second digital signal processor. The second digital signal processor analyzes the noise characteristics and performs adaptive filtering, taking the "noise reference signal" collected by the secondary microphone as input. Since the sound wave propagates in space with slight changes, the second digital signal processor predicts the signal parameters when the "noise reference signal" reaches the position of the main microphone, and dynamically and real-timely generates an "anti-phase noise signal" with the same amplitude but completely opposite phase (180 degrees) of the noise signal according to the prediction result. The generated "anti-phase noise signal" (digital signal) is converted back to an analog signal by a digital-to-analog converter (DAC), and the analog signal drives the loudspeaker in the earphone to emit sound as "anti-phase noise sound wave". The "anti-phase noise sound wave" meets the original environmental noise sound wave actually heard by the human ear in the air and undergoes destructive interference, so that the environmental noise entering the ear canal is greatly weakened or even eliminated, to obtain a relatively pure voice signal, and ensure the freedom of hearing and speaking in extreme environment (underground environment).
[0033] In an embodiment, the relay device dynamically adjusts the transmission power according to the RSSI. The RSSI (Received Signal Strength Indicator) is a measurement of the power present in a received radio signal, and is used to indicate the strength of a received signal by a device such as a relay device, a mobile phone, or a Wi-Fi router. In this embodiment, the relay device dynamically adjusts the transmission power according to the RSSI, which can reduce the power consumption and network interference of the relay device, improve the spectral efficiency, allow more communication links in the same frequency band, and automatically adapt to changes in the wireless environment such as weather, obstacle movement, and device movement, thereby maintaining the stability of the connection and achieving adaptive power control of the relay device. Preferably, the transmission power of the relay device is 10-50 mW. Further, the length of the voice packet formed by the sound signal forwarded by the relay device is limited to within 20 ms to reduce channel occupancy. In addition, in this embodiment, each relay device periodically scans the frequency band to avoid occupied channels. Preferably, the relay device scans the frequency band every 5 minutes to achieve DFS (Dynamic Frequency Selection), i.e., the relay device automatically detects radio frequency interference in its working environment and actively switches to a cleaner channel, thereby ensuring the reliability and efficiency of communication. In addition, the ad hoc network cluster system also includes other anti-interference measures in burst mode, such as, in addition to DFS before signal transmission by the relay device, spread spectrum technology (spreading the original data signal over a wider frequency band for transmission, so that even if part of the frequency band of the original signal is interfered, the receiving end can recover the complete information from other frequency bands through correlation processing to improve the anti-interference ability) or forward error correction (adding redundant error correction codes in the data packet, so that the receiving end can not only detect errors, but also automatically correct errors within a certain limit without retransmission, to avoid additional delay and power consumption caused by retransmission) during signal transmission by the relay device; and automatic retransmission request, acknowledgement frame, and timeout retransmission after signal transmission by the relay device to remedy interference.
[0034] In an embodiment, the relay device and the plurality of body terminals connected thereto form a subsystem, each path of the subsystem occupies a 500 ms time slot, each subsystem is cyclically polled, the ad hoc network cluster system broadcasts in full time period, and each body terminal receives in time division. The parameters and effects of the ad hoc network cluster system are described below in conjunction with specific examples.
[0035] In the embodiment, the ad hoc network cluster system has no base station and is used for signal transmission in the frequency band of 150-470 MHz, and can realize 3-person full-duplex voice, 30-person listening, 4-way relay (150-200 m spacing) transmission effect in 1 MHz bandwidth. Specifically, the ad hoc network cluster system includes three relay devices (relay 1, relay 2 and relay 3) located in the downhole environment, one relay device (relay 4) located on the ground, and 30 personal terminals communicating with each relay device in the downhole environment, i.e. the number n of personal terminals corresponding to each relay device is 30. In this way, the uplink can support 4-person speech (including emergency signal speech received by the ground relay device), each occupying a 500 ms time slot, and through cyclic polling, only a total demand of 4 persons x 2 kbps = 8 kbps is required, and the relay device sends the same voice stream to all receivers through broadcast mode (1 x 2 kbps is required), realizing downlink 30-person listening. Since the number of downhole relay devices is 3, the effective communication distance is 600-800 m in the case of communication with the relay device on the ground. In the embodiment, the radio frequency parameter configuration of the relay device and the personal terminal is as follows: the transmission power is 17 dBm (50 mW), the receiving sensitivity (SF8) is -124 dBm, the antenna gain is 6 dBi omnidirectional, and the fading margin is 15 dB. In addition, in the embodiment, the measured value of the voice end-to-end delay of the ad hoc network cluster system is 86 ms (including hop relay); the relay device switching time is less than 15 ms; the multipath interference suppression is greater than 18 dB (RAKE receiver); and the system capacity supports 5 parallel networks (5 x 1 MHz).
[0036] Further, in the embodiment, when frequency allocation is performed, the frequency point of voice uplink is 151.0-151.4 MHZ, the bandwidth is 4x100 KHZ, the modulation parameter is SF7, CR4 / 5, and 3 persons (underground) TDMA (time division multiple access) are supported in technology for turn-by-turn transmission; the frequency point of voice downlink is 151.5-151.8 MHZ, the bandwidth is 3x100 KHZ, the modulation parameter is SF7, CR4 / 5, and full-time broadcast is supported in technology; the frequency point of broadcast channel is 152.0-152.2 MHZ, the bandwidth is 200 KHZ, the modulation parameter is SF10, CR4 / 8, and 30 listeners are supported in technology for time-sharing reception; the frequency point of relay uplink is 152.3-152.6 MHZ, the bandwidth is 4x75 KHZ, the modulation parameter is SF8, CR4 / 6, and adaptive power control is supported in technology; the frequency point of relay downlink is 152.7-153.0 MHZ, the bandwidth is 4x75 KHZ, the modulation parameter is SF8, CR4 / 6, and directional antenna coupling is supported in technology; the frequency point of signaling channel is 153.1 MHZ, the bandwidth is 25 KHZ, the modulation parameter is SF11, CR4 / 8, and network synchronization and route maintenance are supported in technology. In the case that one relay device is connected with 3 personal terminals (terminal 1, terminal 2 and terminal 3), the time slot allocation table in 20 ms cycle is as follows:
[0037] 0-5 ms 5-10 ms 10-15 ms 15-20 ms Function Terminal 1 transmit Terminal 2 transmit Terminal 3 transmit Relay repeat Frequency 151.0 MHz 151.1 MHz 151.2 MHz 152.3-152.6 MHz Figure 3
[0038] Please refer to The self-organizing network cluster system of the embodiment forms a centerless self-organizing network, and the distributed communication process includes: in time slot 1, voice uplink, terminal 1 sends voice information to relay 1 (relay device 1) according to the frequency of 151.0 MHZ, relay 1 forwards the voice information to relay 2 according to the frequency of 152.3 MHZ in time slot 2, and relay 2 sends the voice information to terminal 2 according to the frequency of 151.5 MHZ in time slot 3, so as to realize voice downlink, so that terminal 2 (personal terminal) can hear the voice information sent by terminal 1. At the same time, relay 2 broadcasts the voice information according to the frequency of 152.0 MHZ, so that all listening terminals (i.e. personal terminals in receiving mode) can hear the voice information sent by terminal 1.
[0039] The self-organizing network cluster system of the mine signal blind area of the embodiment of the present application forms a centerless self-organizing network through multiple relay devices and multiple body terminals, the relay device is based on adaptive radio frequency and mesh protocol, and can realize multi-hop relay, so as to ensure that the communication distance meets the needs of underground and ground communication, the relay devices are connected through LoRa single channel link between the relay devices and the body devices, and the time division multiplexing is realized through the channel and time slot allocation, in this way, through the combination of LoRa single channel and time division multiplexing, full duplex communication capability can be obtained, which can support multiple people to talk and meet the needs of multiple people to talk, and the use of LoRa single channel can reduce the communication cost at the same time; the self-organizing network architecture does not need a center base station, can be quickly deployed and has high reliability, and can restore communication within 30 minutes after a disaster, which is beneficial to the effective development of rescue work.
[0040] The technical features of the above-mentioned embodiments can be combined arbitrarily, and in order to make the description simple, all possible combinations of the technical features in the above-mentioned embodiments are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present application.
[0041] The above-mentioned embodiments only express several embodiments of the present application, the description is more specific and detailed, but it should not be understood as the limitation of the scope of the patent. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.
Claims
1. A self-organizing network cluster system for mine signal blind areas, used for deployment in underground coal mine environments, characterized in that: include: A relay unit, comprising a plurality of relay devices spaced apart, at least one of which is connected to a ground node by wire or wirelessly to receive and transmit emergency signals, each of which adaptively adjusts radio frequency parameters, and adjacent relay devices are connected via a LoRa single-channel link and communicate via the Mesh protocol; as well as The terminal unit includes a plurality of portable terminals, each of which is connected to the nearest or strongest signal relay device via a LoRa single-channel link; the portable terminal enters a transmitting mode when a human voice signal is collected, or enters a receiving mode when no human voice signal is collected; When the relay device receives a random access request sent by a portable terminal in the transmitting mode, it allocates a channel and time slot to the portable terminal, and forwards the personnel voice signal to an adjacent relay device or sends it to the portable terminal in the receiving mode in the broadcast mode; or when the relay device receives an emergency signal, it forwards the emergency signal to an adjacent relay device or sends it to the portable terminal in the receiving mode in the broadcast mode.
2. The ad hoc network cluster system according to claim 1, characterized in that: The relay device includes a first main control MCU, a first RF transceiver connected to the first main control MCU, a first explosion-proof battery connected to the first main control MCU, a first charging interface connected to the first explosion-proof battery, a wired interface connected to the first main control MCU, a first digital signal processor connected to the first main control MCU, and a handset connected to the first digital signal processor and used to collect sound signals or output sound signals. The first main control MCU integrates a LoRa baseband.
3. The ad hoc network cluster system according to claim 2, characterized in that: The relay device further includes a first power amplifier connected to the first radio frequency transceiver and a first antenna switch connected to the first main control MCU.
4. The ad hoc network cluster system according to claim 1, characterized in that: The portable terminal includes a second main control MCU, a second RF transceiver connected to the second main control MCU, a second explosion-proof battery connected to the second main control MCU, a second charging interface connected to the second explosion-proof battery, a second digital signal processor connected to the second main control MCU, an earphone connected to the second digital signal processor and used to output sound signals, and a microphone component connected to the second digital signal processor and used to collect sound signals. The second main control MCU integrates a LoRa baseband.
5. The ad hoc network cluster system according to claim 4, characterized in that: The earphones are bone conduction earphones; the microphone assembly includes a main microphone close to the user's mouth for collecting voice and noise, and a secondary microphone away from the user's mouth for collecting ambient noise; the second digital signal processor receives the sound signals sent by the main microphone and the secondary microphone, calculates the noise field characteristics through a digital noise reduction algorithm, and generates reverse sound waves to offset the noise.
6. The ad hoc network cluster system according to claim 4, characterized in that: The portable device further includes a second power amplifier connected to the second radio frequency transceiver and a second antenna switch connected to the second main control MCU.
7. The ad hoc network cluster system according to claim 1, characterized in that: The relay device and the multiple portable terminals connected to it constitute a subsystem. Each subsystem occupies a 500ms time slot. Each subsystem polls cyclically, broadcasts in the self-organizing network cluster system at all times, and each portable terminal receives in a time-sharing manner.
8. The ad hoc network cluster system according to claim 1, characterized in that: The relay device dynamically adjusts the transmission power according to the RSSI.
9. The ad hoc network cluster system according to claim 1, characterized in that: The length of the voice packet formed by the sound signal forwarded by the relay device is limited to within 20ms.
10. The ad hoc network cluster system according to claim 1, characterized in that: Each of the relay devices periodically scans frequency bands to avoid occupied channels.