Mine emergency data relay transmission method based on LoRa and 4G fusion

Abstract

The invention discloses a mine emergency data relay transmission method based on LoRa and 4G fusion, and belongs to the technical field of mine communication. The method comprises the steps that a communication node monitors sensor data in real time, and when key emergency data is recognized, 4G signal strength is automatically detected; when the 4G signal strength is lower than a set threshold value, starting a LoRa multi-hop relay transmission mode, and selecting an optimal relay node through a dynamic relay node discovery and comprehensive preferential algorithm; the key data is transmitted to an exit node with 4G connection capability through a one-hop or multi-hop LoRa link, and is finally uploaded to a command center through a 4G network. According to the invention, through advantage complementation of LoRa and 4G, a hybrid communication network adaptive to a complex mine environment is constructed, and the technical problem of reliable transmission of key data in a communication blind area is effectively solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of mine communication, and particularly relates to a mine emergency data relay transmission method based on LoRa and 4G fusion. BACKGROUND

[0002] Mine safety production is the lifeline of mining development. The topsoil pit, underground tunnel, and slope area have complex terrain, and there are a large number of communication blind areas. The existing 4G / 5G public network or private network base station signal is affected by factors such as terrain shielding and equipment electromagnetic interference, and it is difficult to achieve full coverage. When personnel or equipment enter these blind areas, their key safety state information (such as abnormal vital signs, environmental parameter over-limit, equipment failure, and active help-seeking signal) cannot be uploaded to the command center, which constitutes a major safety risk.

[0003] The conventional method for solving the blind area communication has obvious disadvantages:

[0004] 1. Additional 4G / 5G base station: high cost, long deployment period, and limited effect on mobile operation surface and temporary blind area.

[0005] 2. Satellite communication: terminal equipment and communication cost are expensive, power consumption is large, and it cannot be used in underground or deep pit, which is not suitable as a full staff standard solution.

[0006] 3. Traditional LoRa network: usually adopts star topology and relies heavily on fixed central gateway. Once the terminal node is located outside the coverage range of the gateway, the communication is interrupted, lacks flexibility, and cannot build a dynamic and self-healing communication network.

[0007] Therefore, there is an urgent need for a blind area emergency communication technology that can adapt to the dynamic environment of the mine, has controllable cost, and high reliability, to ensure that key data can be reliably transmitted back at any location. SUMMARY

[0008] In view of the deficiencies in the prior art, the purpose of the present application is to provide a mine emergency data relay transmission method based on LoRa and 4G fusion, which can ensure that key emergency data can be reliably and timely transmitted to the command center in any mine environment.

[0009] The technical scheme adopted by the application is: a mine emergency data relay transmission method based on LoRa and 4G fusion, and the technical key points are as follows:

[0010] The communication node identifies the key emergency data;

[0011] According to the comparison result of the reference signal received power value of the 4G signal detected by the node and the set threshold value, the 4G direct transmission mode or the LoRa multi-hop relay transmission mode is intelligently selected, wherein the LoRa multi-hop relay transmission mode includes a data transmission mode through one or more relay nodes;

[0012] In the LoRa multi-hop relay transmission mode, the node selects the optimal relay node from the neighbor nodes through an optimization algorithm, and the method for selecting the optimal relay node is as follows: a weighted evaluation algorithm is used to perform weighted operation on the link quality data according to a preset weighting coefficient to obtain a comprehensive score of each candidate node; the comprehensive scores S of the candidate nodes are compared to select the node with the highest comprehensive score as the relay node.

[0013] The critical emergency data is transmitted through the selected relay node in one-hop or multi-hop LoRa link relay transmission until it reaches the exit node with 4G connection capability.

[0014] The exit node sends the critical emergency data to the remote command center through the 4G network.

[0015] Further, the comparison logic of the reference signal received power value of the 4G signal detected by the node and the set threshold value is as follows:

[0016] If the reference signal received power value of the 4G signal is greater than the set threshold value, the 4G direct transmission mode is selected, the node wakes up and configures the 4G module, and the data is directly sent to the cloud server through the 4G network;

[0017] If the reference signal received power value of the 4G signal is not greater than the set threshold value, the LoRa multi-hop relay transmission mode is selected, and the node keeps the 4G module in a dormant state and activates the LoRa multi-hop relay transmission mode.

[0018] Further, the set threshold value is in the range of -95dBm to -100dBm.

[0019] Further, the process of the LoRa multi-hop relay transmission mode includes: the source node broadcasts a relay request, receives the response information of the neighbor nodes, and selects a relay node using an optimization algorithm; wherein the relay request includes a response information data packet, the response information data packet includes the source node ID, the sequence number, the own position and the data priority; the response information of the neighbor nodes includes the neighbor node ID, the 4G signal strength of the neighbor node, the remaining power and the LoRa link signal-to-noise ratio between the source node and the neighbor node.

[0020] Further, the generation conditions of the critical emergency data packet include: the sensor data exceeds the safety threshold, the built-in sensor detects that the impact strength exceeds the set value, and the manual triggered distress signal is received.

[0021] Further, the critical emergency data packet contains a time-to-live field, which is decremented by one for each hop of the LoRa multi-hop relay transmission, and the data packet is discarded when the field value is zero.

[0022] Further, the LoRa link relay transmission also includes an end-to-end acknowledgement mechanism: the exit node sending data over the 4G network sends an acknowledgement message back along the original path through the LoRa link until the acknowledgement message reaches the original source node; if the source node does not receive the acknowledgement message within a timeout period, a retransmission process is triggered.

[0023] Further, the retransmission process refers to the source node increasing the retransmission counter by one; and the node reselects the optimal relay node from the neighbor nodes through an optimization algorithm.

[0024] Further, the LoRa multi-hop relay transmission mode also includes a network topology maintenance mechanism: all nodes periodically broadcast heartbeat information, and each node dynamically maintains a neighbor table according to the received heartbeat information to adapt to network topology changes caused by node movement.

[0025] Further, in the Lo R a The relay transmission process also includes link failure processing: if the source node does not receive any relay response after sending a relay request, or the data packet transmission fails, the backup data packet is extracted for data recovery, and the link score of the critical emergency data packet is recalculated.

[0026] The beneficial effects of the present application are as follows:

[0027] 1) Transmission reliability is significantly improved: through multi-hop relay and end-to-end acknowledgement mechanism, the signal shielding problem in complex mine environment is effectively overcome, and high reliability data transmission in blind area environment is realized;

[0028] (2) Network adaptability is enhanced: dynamic network topology maintenance technology is adopted to automatically adapt to node position changes, significantly improving the communication stability of the system in a mobile scenario;

[0029] (3) System energy efficiency is optimized: through intelligent sleep and transmission mode switching mechanism, device energy consumption is greatly reduced, and the overall endurance time of the system is effectively prolonged;

[0030] (4) Deployment cost advantage: make full use of existing communication infrastructure, reduce special equipment investment, and significantly reduce system deployment and maintenance costs. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings described below only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0032] Fig. 1 System architecture and workflow diagram of the embodiments of the present application;

[0033] Fig. 2 Dynamic relay discovery and optimization algorithm flowchart of the embodiments of the present application;

[0034] Fig. 3 Comparison diagram of the transmission method of the embodiments of the present application and the prior art. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following will further describe the present application in detail with reference to the drawings of the embodiments of the present application and the specific embodiments. Figs. 1-3 DETAILED DESCRIPTION

[0036] The embodiments provide a mine emergency data relay transmission method based on LoRa and 4G fusion, which specifically comprises the following steps:

[0037] Step 101: Key emergency data identification and encapsulation.

[0038] The microcontroller (MCU) of the communication node (hereinafter referred to as "node") periodically reads the connected sensor data through its sensor interface (such as I2C, ADC), including: reading the heart rate value (HR) from the heart rate sensor; reading the methane (CH) concentration from the gas sensor.

[0039] The dynamic data is read from the three-axis accelerometer, and the vector amplitude is calculated, which is used to detect whether the person falls.

[0040] The node is pre-installed with key data discrimination rules. The MCU compares the real-time data with the rule library, and when any condition is met, the key emergency data is triggered:

[0041] Rule 1 (threshold overrun): if it is monitored that the heart rate of the person is continuously higher than 120 times per minute, or the methane gas concentration in the environment exceeds 1.0%, the key emergency data is immediately triggered.

[0042] Rule 2 (severe impact): if the built-in acceleration sensor detects that the impact intensity change amplitude recorded within 200 milliseconds exceeds g, the key emergency data is immediately triggered.

[0043] Rule 3 (Manual SOS): If the SOS button GPIO input is high, indicating that a manual SOS signal has been received, trigger the critical emergency data immediately.

[0044] Once triggered, the MCU encapsulates the data immediately. The data packet structure is shown in Table 1:

[0045] Table 1: Data packet structure

[0046]

[0047] In Table 1, 1 is the start delimiter: 1 byte in length, with a fixed value of 0xAA in hexadecimal, used for frame synchronization in the data stream, indicating the start of a data packet. 2 is the packet length: 1 byte in length, indicating the total number of bytes of all data from the field after this field to the cyclic redundancy check code field before it. 3 is the source node identifier: 4 bytes in length, used to uniquely identify the source node that sends the critical emergency data. 4 is the sequence number: 2 bytes in length, which is incremented each time the data packet is sent, used for sequential identification of data packets, de-duplication, and implementation of the confirmation mechanism. 5 is the priority and time to live: 1 byte in length. The high 4 bits of this byte represent the priority of the data packet, with the highest priority being 0xF; the low 4 bits represent the time to live of the data packet, with an initial value of 7, which is decremented by 1 for each hop of the relay node. 6 is the timestamp: 4 bytes in length, using Unix timestamp format, recording the precise time of generation of the critical emergency data. 7 is the geographic location information: a total of 8 bytes, of which the latitude and longitude each occupy 4 bytes, stored in floating-point format, recording the location of the node that triggered the event. 8 is the data type: 1 byte in length, used to identify the specific type of critical emergency data, for example: 0x01 represents heart rate data, 0x02 represents gas concentration data, and 0x03 represents manual SOS signal. 9 is the data payload: N bytes in length, used to carry specific sensor readings (such as heart rate value, gas concentration value) or event code. 10 is the cyclic redundancy check code: 2 bytes in length, used to check the entire data packet (from the start delimiter to the end of the data payload) to detect errors in the data during transmission.

[0048] Step 102: Intelligent decision of transmission mode.

[0049] After the data packet is encapsulated, the MCU queries the current RSRP value of the 4G module through a serial port command. This command is based on the standard control protocol (AT instruction set) of the communication module. The threshold value T good can be configured through the cloud, and the typical value of T good is -95dBm to -100dBm.

[0050] The best transmission path decision logic for key emergency data is selected according to the 4G signal strength in this embodiment:

[0051] If the 4G signal RSRP > T good, the 4G direct transmission mode is selected, the node wakes up and configures the 4G module, and the data is directly sent to the cloud server (IP:Port) through the TCP socket of the 4G network.

[0052] If the 4G signal RSRP ≤ T good: the LoRa multi-hop relay transmission mode is selected, the node keeps the 4G module in a dormant state, activates the LoRa multi-hop relay transmission mode, and performs step 103.

[0053] Step 103: Dynamic relay node discovery and optimal selection.

[0054] The specific process of the dynamic relay discovery and optimal selection algorithm is shown in Fig. 2 , which mainly includes the following steps:

[0055] Broadcast relay request: the source node broadcasts a relay request RREQ packet through the LoRa module at a pre-set frequency and spreading factor. The RREQ packet in this embodiment contains: source node ID (Source ID), sequence number (Sequence Number), own position and data priority.

[0056] Collect neighbor response: after receiving the RREQ, the neighbor node first checks the sequence number to prevent repeated processing. Then, the neighbor node prepares a relay response RREP packet, which contains: neighbor node ID, neighbor node 4G RSRP value (read from its own 4G module), neighbor node remaining power (read battery voltage through MCU ADC and convert), LoRa signal-to-noise ratio (SNR) of this RREQ reception.

[0057] To avoid wireless conflict, the neighbor node will wait for a random backoff time Backoff time before replying, the calculation formula is:

[0058] Backoff_time = random(0, N) * SlotTime

[0059] In the formula, N is 10 and SlotTime is 20 ms.

[0060] The optimal algorithm is used to select the relay node in this embodiment: the source node starts a 200 ms collection timer. After the timer ends, it processes all the valid RREP packets collected, and for each candidate neighbor node i, the comprehensive score S i is calculated, the formula is as follows:

[0061] The normalization function is defined as follows:

[0062]

[0063] In the formula, f(RSSI) 4G () indicates the 4G signal quality score. RSSI represents the 4G signal reception strength of the i-th node. max Optimal signal strength threshold, RSSI min Worst signal strength threshold, where RSSI max = -70dBm, RSSI min = -120dBm, values ​​outside the range are clamped to 0 or 1.

[0064]

[0065]

[0066] In the formula, f(Battery) represents the battery capacity score, and f(SNR) represents the battery rating. LoRa () represents the LoRa quality rating, BatteryLevel. i SNR represents the remaining battery percentage of the i-th node. i Represents the LoRa signal-to-noise ratio (SNR) of the i-th node. max SNR represents the optimal signal-to-noise ratio threshold. min SNR represents the worst signal-to-noise ratio threshold. max =10dB, SNR min = -20dB.

[0067] Then, the overall score is calculated:

[0068] S i =α·f(RSSI) 4G ) i +β·f(Battery) i +γ·f(SNR LoRa ) i

[0069] In this embodiment, the weighting coefficients are set as follows: α = 0.6, β = 0.2, γ = 0.2. This weighting configuration emphasizes selecting the node most likely to transmit data back to the 4G network directly or with fewer hops. Source node selection S i The neighbor node with the highest value is used as the next-hop relay.

[0070] Step 104: Data relay transmission and end-to-end confirmation.

[0071] The source node sends the critical emergency data packet to the selected relay node in the confirmation transmission mode through the LoRa link. The receiving node needs to reply an ACK frame at the LoRa layer.

[0072] After receiving the data, the MCU of the relay node first performs CRC check. After the check passes, it reduces the time to live TTL field in the packet header by 1. If TTL == 0, the packet is discarded and an error log is recorded.

[0073] The relay node immediately performs step 102 recursively, becomes a new source node, and finds the next hop.

[0074] Confirmation mechanism: After a certain relay node (outlet node) successfully uploads data to the cloud server through the 4G network, the cloud replies a TCP ACK to it. The outlet node immediately generates an application layer ACK frame, which contains the original source node ID and sequence number. The ACK frame packet is transmitted back to the original source node along the reverse direction of the RREP reply path through the LoRa link, hop by hop. Each hop uses the confirmation transmission mode. If the original source node does not receive the ACK frame within the set total timeout time (such as 30 seconds), it indicates that the end-to-end transmission fails, and it will start the retransmission process, up to 3 times. The transmission failure in this embodiment may be: the data packet is lost on a certain hop LoRa link; a certain relay node fails; the 4G connection of the outlet node is unstable, and fails to upload data or fails to receive the reply from the cloud.

[0075] The retransmission in this embodiment means that the source node increases the retransmission counter by 1. Since the previous path has failed, the network topology or node state may have changed, such as node movement, power consumption, signal quality change, so the step 103 of dynamic relay node discovery and optimal selection is re-executed, a new and better transmission path is found, and the new relay node repeats the relay process until the data reaches the outlet node and is uploaded through 4G.

[0076] Step 105: network topology maintenance and mobility adaptation.

[0077] The LoRa transmission mode uses a heartbeat mechanism, and all nodes broadcast a beacon frame every 60 seconds. The beacon frame is lightweight and contains node ID, location, 4G RSRP, remaining power, and neighbor number. The node is in low-power reception mode during the non-transmission period, listens to the beacon frame to update its neighbor information table. The table records the node ID, last signal-to-noise ratio, last power, and other information of each neighbor, and has an aging time, such as 180 seconds. The neighbors that are not updated within the timeout will be removed.

[0078] Link failure handling: In the relay transmission process, if the source node does not receive any RREP after sending RREQ, or the packet sending fails, it will directly select a node with the highest comprehensive score from the neighbor information table as a backup relay. If the neighbor table is empty, it will wait for the next heartbeat period and then retry. The purpose is to ensure the success rate and efficiency of the whole LoRa multi-hop transmission process when the LoRa link of a certain hop fails, without relying on rebroadcasting RREQ, but using the real-time neighbor information table maintained by the heartbeat mechanism to select a backup path.

[0079] From Fig. 3 It can be seen that after the comparison of the two methods, the method of the embodiment has significant improvement in network adaptability, transmission reliability and system energy efficiency, and the deployment cost is greatly reduced.

[0080] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for emergency data relay transmission in mines based on the integration of LoRa and 4G, characterized in that, Includes the following steps: Communication nodes identify critical emergency data; Based on the comparison between the reference signal received power value of the 4G signal detected by the node and the set threshold, the system intelligently selects either the 4G direct transmission mode or the LoRa multi-hop relay transmission mode. The LoRa multi-hop relay transmission mode includes data transmission through one or more relay nodes. In LoRa multi-hop relay transmission mode, nodes select the optimal relay node from neighboring nodes using an optimization algorithm. The method for selecting the optimal relay node is as follows: a weighted evaluation algorithm is used to perform weighted calculations on the link quality data according to preset weighting coefficients to obtain the comprehensive score of each candidate node; the comprehensive scores S of each candidate node are compared to select the node with the highest comprehensive score as the relay node. Critical emergency data is relayed through the selected relay nodes via one or more LoRa links until it reaches the exit node with 4G connectivity. The exit node transmits the critical emergency data to the remote command center via a 4G network.

2. The mine emergency data relay transmission method based on LoRa and 4G integration as described in claim 1, characterized in that, The comparison logic between the reference signal received power value and the set threshold for node detection of 4G signals is as follows: If the reference signal received power value of the 4G signal is greater than the set threshold, the 4G direct transmission mode is selected, the node is woken up and the 4G module is configured, and the data is sent directly to the cloud server through the 4G network. If the reference signal received power value of the 4G signal is not greater than the set threshold, the LoRa multi-hop relay transmission mode is selected, the node keeps the 4G module in sleep mode, and activates the LoRa multi-hop relay transmission mode.

3. The mine emergency data relay transmission method based on LoRa and 4G integration according to claim 2, characterized in that, The set threshold value ranges from -95dBm to -100dBm.

4. The mine emergency data relay transmission method based on LoRa and 4G integration according to claim 1, characterized in that, The LoRa multi-hop relay transmission mode includes: the source node broadcasting a relay request, receiving response information from neighboring nodes, and using an optimization algorithm to select a relay node; wherein the relay request includes a response information data packet, the response information data packet including the source node ID, sequence number, its own location, and data priority; the response information of the neighboring node includes the neighboring node ID, the neighboring node's 4G signal strength, remaining battery power, and the LoRa link signal-to-noise ratio between the neighboring node and the source node.

5. The mine emergency data relay transmission method based on LoRa and 4G integration according to claim 1, characterized in that, The conditions for generating the critical emergency data packet include: sensor data exceeding a safety threshold, the built-in sensor detecting an impact intensity exceeding a set value, and receiving a manually triggered distress signal.

6. The mine emergency data relay transmission method based on LoRa and 4G integration according to claim 1, characterized in that, Critical emergency data packets contain a time-to-live field. During LoRa multi-hop relay transmission, the value of this field is decremented by one for each hop relay node. When the value of this field is zero, the data packet is discarded.

7. The mine emergency data relay transmission method based on LoRa and 4G integration according to claim 1, characterized in that, The LoRa link relay transmission also includes an end-to-end confirmation mechanism: the exit node that transmits data through the 4G network sends a confirmation message in reverse along the original path through the LoRa link until the confirmation message reaches the original source node; if the source node does not receive the confirmation message within the timeout period, a retransmission process is triggered.

8. The mine emergency data relay transmission method based on LoRa and 4G integration as described in claim 7, characterized in that, The retransmission process described refers to the following: the source node increments the retransmission counter by 1; the node then selects the optimal relay node from its neighboring nodes using an optimization algorithm.

9. A mine emergency data relay transmission method based on LoRa and 4G integration according to claim 1, characterized in that, LoRa multi-hop relay transmission mode also includes a network topology maintenance mechanism: all nodes periodically broadcast heartbeat information, and each node dynamically maintains its neighbor table based on the received heartbeat information to adapt to network topology changes caused by node movement.

10. A mine emergency data relay transmission method based on LoRa and 4G integration according to claim 1, characterized in that, The LoRa relay transmission process also includes link failure handling. If the source node does not receive any relay response after sending a relay request, or if the data packet transmission fails, the backup data packet is extracted for data recovery, and the link score of the critical emergency data packet is recalculated.

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