CN113507703B - LoRa multi-hop communication method and system for field rescue - Google Patents

Abstract

The invention discloses a LoRa multi-hop communication method and system for field rescue. The system includes a rescue node terminal, a network access node terminal, a LoRa gateway, a server and a remote information terminal; after the network access node terminal joins the LoRaWAN network where the LoRa gateway is located, It works in Class C mode and communicates with the rescue node terminal in the Receive Window RX2 window specified by LoRaWAN. The rescue node terminal, the network access node terminal and the LoRa gateway form a LoRa multi-hop communication network. The LoRa multi-hop communication method and system for field rescue disclosed by the invention have better field adaptability, and can enable search and rescue personnel to obtain information such as the location of the rescuer faster and more accurately, and at the same time upload the location information of the search and rescue personnel in time , which provides a guarantee for improving rescue efficiency and ensuring the safety of search and rescue personnel.

Description

A LoRa multi-hop communication method and system for field rescue

technical field

The invention belongs to the field of Internet of Things, and in particular relates to a LoRa multi-hop communication method and system for field rescue.

Background technique

When people conduct field exploration, exploration, camping or tourism, due to complex environments such as deserts, swamps or forests, as well as abnormal climate changes, once danger occurs, they need to call for help in time; however, due to complex environment and other factors, rescue It is difficult for the team to obtain information such as the current location and movement trajectory of the emergency callers in the first time, resulting in delays in the golden rescue time. The typical feature of the Internet of Things is to form a wireless self-organizing network system through sensing nodes deployed in the monitoring area, so as to cooperatively sense, collect and process the information of the sensed objects in the network coverage area, and send it to the observer. It is foreseeable that with the rapid development of the Internet of Things technology and its wide application in various fields, the use of its wireless self-organization, cooperative perception and other characteristics will improve the environmental practicability of the field rescue system, so that search and rescue personnel can obtain emergency personnel faster and more accurately. Location and other information will become the inevitable development trend of field rescue system research.

At present, the design idea of many rescue systems is to use smart wearable devices to monitor the physical state, geographical location and other information of the callers, and then upload the monitoring information to the network rescue platform through GPRS and other technologies; however, due to the base station facilities in the wild environment The number is very limited (or even none), and the above rescue system architecture can only be applied to a small number of application scenarios. In addition, some rescue systems use the Beidou satellite navigation system, ZigBee and other Internet of Things technologies to design and implement the field rescue system; however, the inherent high energy consumption, high cost and low endurance of satellite navigation systems, and the transmission distance of ZigBee technology. Shortage and weak penetration ability restrict the further development of these rescue systems.

At present, the Internet of Things technologies such as Zigbee, WIFI, and GPRS have been used in various rescue systems. However, due to the limited transmission distance and high power consumption of traditional Internet of Things technologies such as Zigbee, WIFI, and GPRS, it is difficult to apply them in the wild environment. The scope is very small, and it is difficult to promote the application in the case of wide search and rescue areas and complex environments; compared with the shortcomings of traditional Internet of Things technologies such as ZigBee, WIFI, and GPRS when applied to field rescue systems, the emerging Internet of Things technology proposed in 2013. ——LoRa (Long Range) technology, using spread spectrum communication mode, the link budget of up to 157db makes the communication distance up to 15 kilometers (in an open environment), and its receiving current is only 10mA, sleep current is only 200nA, can The battery life is greatly extended, which not only helps to solve the problem of the small search and rescue range of the current rescue system, but also provides a guarantee for the equipment to operate for a long time in the wild.

LoRaWAN is a set of protocol standards based on the MAC layer proposed by the LoRa Alliance based on the LoRa physical layer transmission technology. It adopts a single-hop and star network architecture, and the network deployment is flexible, which is conducive to the rapid popularization of LoRa technology. However, in recent years, with the low-power wide-area network (LPWAN) technology represented by LoRa, in complex environments such as field environment rescue, underground pipe network monitoring, building intelligent meter reading, and underground depot management There are more and more applications, and some deficiencies in the LoRa application process have gradually emerged. That is, the single-hop and star network architecture deployment adopted by LoRa still faces problems such as large path loss in scenarios such as many obstacles. Many Researchers have started research on LoRa multi-hop communication technology.

Therefore, using LoRa multi-hop communication technology to design and implement a field rescue system will greatly improve the complex environment adaptability of the field rescue system, and provide a new idea for improving the efficiency of field rescue.

SUMMARY OF THE INVENTION

Different from many existing researches on how to use routing protocols for multi-hop communication between LoRa terminals, the present invention provides a research status that most LoRa terminal products are developed based on LoRaWAN specifications and LoRaWAN only supports single-hop communication. A LoRa multi-hop communication method and system for field rescue will have very good advantages in promotion and application.

The core idea of the LoRa multi-hop communication method provided by the present invention is: placing the network access node joining the LoRaWAN network in the Class C working mode, the network access node will communicate with other rescue nodes in the Receive Window RX2 window specified by LoRaWAN, the network access node, The rescue nodes communicate with each other according to a multi-hop communication protocol designed in this paper, so that the rescue nodes, network access nodes and LoRa gateways form a LoRa multi-hop communication network.

The technical scheme provided by the present invention is as follows:

On the one hand, a LoRa multi-hop communication method for field rescue uses a network access node to join the LoRaWAN network where the LoRa gateway is located, and the network access node is set in the Class C working mode, and the Receive Window RX2 window specified by LoRaWAN is connected to the LoRaWAN network. The rescue node communicates, and the rescue node, the network access node and the LoRa gateway form a LoRa multi-hop communication network; the rescue node and the network access node use the same preamble at the physical layer;

The rescue node periodically sends data packets, and forwards the data packets received from other rescue nodes according to the set rules, and the network access node forwards the received data packets to the LoRa through the LoRaWAN network according to the communication format specified by LoRaWAN. gateway.

Both the rescue node and the network access node belong to the mobile terminal, the rescue node is used to send and receive rescue information, and the network access node is used to forward the rescue information; after the network access node receives the data packet sent by the rescue node, it will not forward it to other places. The rescue node or the network access node, that is, the data packets only go up to the gateway to the server through the network access node, and are not sent to other network access nodes or rescue nodes through the network access node.

Further, the data packet is composed of a control field and a data load;

The control field includes the source device ID, the forwarding device ID, the data packet sequence number SEQ and the maximum forwarding times TTL; the data load includes the node working mode, the user identity, the location information obtained for the first time after the node is powered on, and the current time, current Location information and current time.

Further, the rescue node is provided with two working modes: a distress call mode and a search and rescue mode, and the rescue node processes the received data packets according to the following steps:

Step 1, after receiving the data packet, the rescue node checks whether the duplicate data packet is received, and if the duplicate data packet is received, discarding processing is performed and the remaining steps are not performed, otherwise, the received data packet is recorded and goes to step 2;

Step 2, check whether the rescue node itself is in the distress call mode or the search and rescue mode, if it is in the distress call mode, perform step 3, and if it is in the search and rescue mode, perform step 4;

Step 3, check the working mode of the node in the data packet, if it is in the search and rescue mode, present the current location information and the current time in the data packet to the rescuer to inform the rescuer of the location, and then perform step 5, if it is in the rescue mode, directly Execute step 5;

Step 4, check the working mode of the node in the data group, if it is in the call for help mode, display all the location information and the acquisition time in the data group locally, which is used to instruct the search and rescue personnel to go to the rescue, and then go to step 5, if it is in the search and rescue mode, execute directly step 5;

Step 5: Check whether the data packet reaches the maximum number of forwarding times, if not, reduce the remaining number of forwarding times in the data packet by 1, and then use broadcast to forward to other rescue nodes and network access nodes, otherwise it is directly discarded.

On the other hand, a LoRa multi-hop communication system for field rescue, including rescue node terminal, network access node terminal, LoRa gateway, server and remote information terminal;

The network access node terminal, the LoRa gateway and the server form a LoRaWAN network based on the LoRaWAN protocol, and the rescue node terminal, the network access node terminal and the LoRa gateway form a LoRa multi-hop communication network;

The rescue node terminal and the network access node terminal include a microprocessor module, a LoRa communication module, a display module, a Beidou positioning module and a power supply module, and the LoRa communication module, the display module, the Beidou positioning module and the power supply module are all connected with the microprocessor. connected to the device module;

The network access node terminal joins the LoRaWAN network where the LoRa gateway is located, and the network access node terminal is set in the Class C working mode, and communicates with the rescue node terminal in the Receive Window RX2 window specified by LoRaWAN. Communicate through a multi-hop protocol; the rescue node terminal and the network access node terminal use the same preamble at the physical layer;

The server manages the LoRaWAN network and provides MQTT subscription services. The remote information terminal network access node terminal communicates with the server through the Internet, and subscribes to the data packets sent by the network access node terminal through the MQTT protocol. Realize the display and processing of relevant geographic location information in the rescue process.

The system has good field adaptability, which enables the search and rescue personnel to obtain information such as the location of the rescuers faster and more accurately, and upload the location information of the search and rescue personnel in time, so as to provide technical support for improving the rescue efficiency and ensuring the safety of the search and rescue personnel.

The multi-hop research based on the LoRaWAN specification is convenient for the utilization of equipment in various scenarios after forming, and realizes the true interconnection of all things. For example, with the gradual application of LoRaWAN products in forest parks, camping bases and other scenarios, the terminals added to the LoRaWAN network can be used for the management of equipment such as street lamps; through the method of the present invention, after simply upgrading the existing LoRa terminal software program, The existing LoRaWAN system can be equipped with additional rescue functions, that is, it allows rescue nodes to form a multi-hop network with existing LoRa terminals and LoRa gateways, so as to complete the transmission of various types of rescue information.

Further, the rescue node terminal periodically sends data packets, and forwards the data packets received from other rescue node terminals according to the set rules. After the network access node terminal receives the data packets sent by the rescue node terminal, It is no longer forwarded to other rescue node terminals or the network access node terminal, and the network access node terminal forwards the received data packets to the LoRa gateway through the LoRaWAN network according to the communication format specified by LoRaWAN.

Further, the network access node terminal periodically sends data packets to the server through the LoRaWAN network, and the load of the data packet includes the following location-related information: current location information and current time of the network access node terminal.

Further, the rescue node terminal is provided with two working modes: a distress call mode and a search and rescue mode, and the rescue node terminal processes the received data packets according to the following steps:

Step 1: After receiving the data packet, the rescue node terminal checks whether it has received the duplicate data packet. If it receives the duplicate data packet, it discards the data packet and does not perform the remaining steps. Otherwise, the received data packet is recorded and goes to step 2. ;

Step 2, check whether the rescue node terminal itself is in the distress call mode or the search and rescue mode, if it is in the distress call mode, perform step 3, and if it is in the search and rescue mode, perform step 4;

Step 3, check the working mode of the rescue node terminal in the data packet, if it is in the search and rescue mode, present the current location information and the current time in the data packet to the rescuer, which is used to inform the rescuer of the location, and then go to step 5, if it is in the rescue mode. Then directly execute step 5;

Step 4: Check the working mode of the rescue node terminal in the data packet. If it is in the distress mode, display all the location information and the acquisition time in the data packet on the rescue node terminal, which is used to instruct the search and rescue personnel to go to the rescue, and then go to Step 5. If In search and rescue mode, step 5 is directly executed;

Step 5: Check whether the data packet reaches the maximum number of forwarding times, if not, reduce the remaining forwarding times in the data packet by 1, and use broadcast to forward to other rescue node terminals and network access node terminals, otherwise directly discard.

Further, the remote information terminal obtains the movement trajectory of the rescuer or the rescuer according to the following steps:

Step A, the telematics terminal obtains the data packets of all rescue node terminals held by a certain rescuer or a certain search and rescue personnel from the server;

Step B, according to the time when the rescue node terminal obtained the location information for the first time after the rescue node terminal is powered on included in the data packet, according to the order of time from small to large, sort all rescue node terminals corresponding to the time;

In step C, according to the current position of the rescue node terminal contained in the data packet, the movement trajectory of the rescuer or the rescuer is obtained.

Further, the rescue node terminal periodically sends data packets, wherein the period T=T ₀ +rand() seconds, T ₀ is a fixed time length, and rand( ) is a random number between 0-1.

beneficial effect

Compared with the prior art, the present invention has the following technical effects:

(I) The technical solution of the present invention makes full use of the advantages of LoRa technology, such as wide coverage, large connection, low power consumption, low cost, etc., at the same time, by setting the working mode and communication mode of the network access node, and combining the design of multiple The hop communication protocol expands the multi-hop communication capability of LoRa, so that the system can better solve the problem of unreliable transmission performance in field scenarios such as many obstacles, which can make the system have better adaptability to the field environment and enable search and rescue personnel Obtain information such as the location of emergency personnel faster and more accurately, and provide technical support for improving rescue efficiency.

(II) The technical solution of the present invention expands the LoRa multi-hop communication capability on the basis of the LoRaWAN network, which can not only make full use of the mature technology of the LoRaWAN network to improve the overall reliability of the system; but also make full use of the existing LoRaWAN terminal products and server systems in the market. and other rich resources, through simple expansion to complete the design of rescue nodes, network access nodes, servers and apps, shorten the development cycle of related products, and reduce product costs.

(III) The rescue node provided by the technical solution of the present invention can be used jointly by the rescuers and the search and rescue personnel, so that the search and rescue personnel can send their own location and other information to the server in time during the search process, so as to ensure the safety of the search and rescue personnel during the rescue process. technical support.

Description of drawings

Fig. 1 is the framework diagram of a kind of field rescue system based on LoRa multi-hop communication described in the specific example of the present invention;

Fig. 2 is the format of the data packet that rescue node periodically sends in the specific example of the present invention;

Figure 3 is the complex scene where the rescue process test is located;

Figure 4 shows the actual measurement positions of the gateway, the network access node and the rescue node in the rescue process test;

Figure 5 shows the progress of the rescue that the rescue commander can grasp.

Detailed ways

The specific content of the present invention will be further explained in detail below in conjunction with the embodiments.

The invention can improve the complex environment adaptability of the field rescue system and improve the field rescue efficiency. The basic implementation idea is as follows: when the field rescuers find themselves in a dangerous situation, they can use the rescue node terminal they carry with them to send out a rescue signal, and rescue themselves during self-rescue. During the process, rescue nodes are deployed along the way; search and rescue personnel first use network access node terminals, LoRa gateways and servers to form a LoRaWAN network, and then carry rescue node terminals to carry out search and rescue, and deploy rescue node terminals along the way during the search and rescue process; remote information terminals obtain rescue by accessing the server The data of the node terminal, the network access node terminal and the LoRa gateway, and various information during the rescue process are displayed on the electronic map, so that the rescue commander can grasp the situation in time and take countermeasures; because the rescue node terminal and the network access node terminal can form LoRa Multi-hop communication network, so when the rescue node terminal carried by the search and rescue personnel successfully communicates with any rescue node terminal carried by the caller or deployed along the way, not only the search and rescue personnel can know the current location and location of the caller through the rescue node terminal carried by themselves. Movement trajectory, and rescue commanders can view all the movement trajectories of callers and search and rescue personnel through remote information terminals such as PCs, tablets or mobile phones, so as to grasp the progress of the rescue in a timely and comprehensive manner; because the movement trajectories of search and rescue personnel can also be displayed on the information terminal. Therefore, when the search and rescue personnel are in danger, they can switch to the call for help mode, so that other search and rescue personnel can quickly rescue themselves, which further improves the rescue effect of the entire system.

Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of the present application all fall into the protection scope of the present invention. .

This embodiment provides a LoRa multi-hop communication method for field rescue. The network access node is used to join the LoRaWAN network where the LoRa gateway is located, and the network access node is set in the Class C working mode, and the Receiver specified by LoRaWAN is used. The Window RX2 window communicates with the rescue node, and the rescue node, the network access node and the LoRa gateway form a LoRa multi-hop communication network; the rescue node and the network access node use the same preamble at the physical layer;

The rescue node periodically sends data packets, and forwards the data packets received from other rescue nodes to the network access node by broadcasting according to the set rules. The network is forwarded to the LoRa gateway.

The rescue node periodically sends data packets, and the data packets are composed of a control field and a data load, wherein the control field includes a source device ID (Source_ID), a forwarding device ID (Forward_ID), a data packet sequence number SEQ and a maximum forwarding times TTL, The data load includes the node working mode (Mode), the user ID (Person_ID), the position information (Position_0) and the current time (Time_0), the current position information (Position_N) and the current time (Time_N) obtained for the first time after the node is powered on. as shown in picture 2;

The rescue node is set to have two working modes: a distress call mode and a search and rescue mode, and the rescue node processes the received data packets according to the following steps:

Step 1, after receiving the data packet, the rescue node checks whether the duplicate data packet is received, and if the duplicate data packet is received, discarding processing is performed and the remaining steps are not performed, otherwise, the received data packet is recorded and goes to step 2;

Step 2, check whether the rescue node itself is in the distress call mode or the search and rescue mode, if it is in the distress call mode, perform step 3, and if it is in the search and rescue mode, perform step 4;

Step 3, check the working mode of the node in the data packet, if it is in the search and rescue mode, present the current location information and the current time in the data packet to the rescuer to inform the rescuer of the location, and then perform step 5, if it is in the rescue mode, directly Execute step 5;

Step 4, check the working mode of the node in the data group, if it is in the call for help mode, display all the location information and the acquisition time in the data group locally, which is used to instruct the search and rescue personnel to go to the rescue, and then go to step 5, if it is in the search and rescue mode, execute directly step 5;

Step 5: Check whether the data packet reaches the maximum number of forwarding times, if not, reduce the remaining number of forwarding times in the data packet by 1, and then use broadcast to forward to other rescue nodes and network access nodes, otherwise it is directly discarded.

Both the rescue node and the network access node belong to the mobile terminal, the rescue node is used to send and receive rescue information, and the network access node is used to forward the rescue information; after the network access node receives the data packet sent by the rescue node, it will not forward it to other places. The call for help node or the network access node, that is, the data packet only goes up through the network access node to the gateway to the server, and is no longer sent to other network access nodes or rescue nodes through the network access node.

This embodiment also provides a LoRa multi-hop communication system for field rescue, as shown in Figure 1, including rescue node terminals, network access node terminals, LoRa gateways, servers and remote information terminals;

The network access node terminal, the LoRa gateway and the server form a LoRaWAN network based on the LoRaWAN protocol, and the rescue node terminal, the network access node terminal and the LoRa gateway form a LoRa multi-hop communication network;

The rescue node terminal and the network access node terminal include a microprocessor module, a LoRa communication module, a display module, a Beidou positioning module and a power supply module, and the LoRa communication module, the display module, the Beidou positioning module and the power supply module are all connected with the microprocessor. connected to the device module;

The network access node terminal joins the LoRaWAN network where the LoRa gateway is located, and the network access node terminal is set in the Class C working mode, and communicates with the rescue node in the Receive Window RX2 window specified by LoRaWAN; the rescue node terminal and the network access node. The node terminal uses the same preamble at the physical layer;

The server manages the LoRaWAN network and provides MQTT subscription services, the remote information terminal communicates with the server through the Internet, and subscribes to the data packets sent by the network node terminal through the MQTT protocol, and realizes the rescue process by extracting the load content of the data packets. Display and processing of relevant geographic location information in .

The system has good field adaptability, which enables the search and rescue personnel to obtain information such as the location of the rescuers faster and more accurately, and upload the location information of the search and rescue personnel in time, so as to provide technical support for improving the rescue efficiency and ensuring the safety of the search and rescue personnel.

The multi-hop research based on the LoRaWAN specification is convenient for the utilization of equipment in various scenarios after forming, and realizes the true interconnection of all things. For example, with the gradual application of LoRaWAN products in forest parks, camping bases and other scenarios, the terminals added to the LoRaWAN network can be used for the management of equipment such as street lamps; through the method of the present invention, after simply upgrading the existing LoRa terminal software program, The existing LoRaWAN system can be equipped with additional rescue functions, that is, it allows rescue nodes to form a multi-hop network with existing LoRa terminals and LoRa gateways, so as to complete the transmission of various types of rescue information.

The rescue node terminal periodically sends data packets, and forwards the data packets received from other rescue node terminals according to the set rules. After receiving the data packets sent by the rescue node terminal, the network access node terminal does not forward any more. To the other rescue node terminals or the network access node terminal, the network access node terminal forwards the received data packets to the LoRa gateway through the LoRaWAN network according to the communication format specified by LoRaWAN.

The network access node terminal periodically sends data packets to the server through the LoRaWAN network, and the load of the data packet includes the following location-related information: current location information and current time of the network access node terminal.

The rescue node terminal is provided with two working modes: a distress call mode and a search and rescue mode, and the rescue node terminal processes the received data packets according to the following steps:

Step 1: After receiving the data packet, the rescue node terminal checks whether it has received the duplicate data packet. If it receives the duplicate data packet, it discards the data packet and does not perform the remaining steps. Otherwise, the received data packet is recorded and goes to step 2. ;

Step 2, check whether the rescue node terminal itself is in the distress call mode or the search and rescue mode, if it is in the distress call mode, perform step 3, and if it is in the search and rescue mode, perform step 4;

Step 3, check the working mode of the rescue node terminal in the data packet, if it is in the search and rescue mode, present the current location information and the current time in the data packet to the rescuer, which is used to inform the rescuer of the location, and then go to step 5, if it is in the rescue mode. Then directly execute step 5;

Step 4: Check the working mode of the rescue node terminal in the data packet. If it is in the distress mode, display all the location information and the acquisition time in the data packet on the rescue node terminal, which is used to instruct the search and rescue personnel to go to the rescue, and then go to Step 5. If In search and rescue mode, step 5 is directly executed;

Step 5: Check whether the data packet reaches the maximum number of forwarding times, if not, reduce the remaining forwarding times in the data packet by 1, and use broadcast to forward to other rescue node terminals and network access node terminals, otherwise directly discard.

The remote information terminal obtains the movement track of the rescuer or the rescuer according to the following steps:

Step A, the telematics terminal obtains the data packets of all rescue node terminals held by a certain rescuer or a certain search and rescue personnel from the server;

Step B, according to the time when the rescue node terminal obtained the location information for the first time after the rescue node terminal is powered on included in the data packet, according to the order of time from small to large, sort all rescue node terminals corresponding to the time;

In step C, according to the current position of the rescue node terminal contained in the data packet, the movement trajectory of the rescuer or the rescuer is obtained.

The rescue node terminal periodically sends data packets, wherein the period T=T ₀ +rand() seconds, T ₀ is a fixed time length, and rand( ) is a random number between 0-1.

In order to verify the effectiveness of this scheme, a rescue process test was carried out for this scheme.

The rescue process test is carried out in the scene with a large number of houses, trees and other obstacles as shown in Figure 3, to prove that this solution can not only realize LoRa multi-hop communication, but also improve the rescue efficiency while protecting the search and rescue personnel themselves. Provide technical support for safety.

During the experiment, node 2 is the rescue node carried by the rescuers, node 1 is the network access node placed within the range of normal communication with the gateway, and node 2 cannot communicate with node 1; node 4 is the rescue node carried by the search and rescue personnel. During the test, the gateway was erected on a small soil slope with a height of about 2 meters. The antenna height of the network access node and the rescue node was not more than 1 meter, and it was randomly deployed in the corner of the low house and the bottom of the pole. During the rescue process, the actual measurement positions of the gateway, network access node and rescue node are shown in Figure 4.

After the experiment started, the rescue node 2 carried by the rescuers could not communicate with the node 1. When the rescue node 4 carried by the search and rescue personnel entered the communication range of the node 2, the node 2 realized the communication with the node 1 through the forwarding of the node 4, so as to realize the node 1. 2. The multi-hop communication between node 4, node 1 and the gateway enables the information such as the location of the caller to be uploaded to the server in time, and the relevant information of the entire rescue process, such as the location and identification of the node, is displayed on the remote information terminal. According to the relevant information displayed on the remote information terminal, the rescue commander can accurately and timely obtain the movement trajectories of the callers and search and rescue personnel, so as to grasp the progress of the rescue in a timely and comprehensive manner; Figure 5 shows the information displayed by the rescue commander on the remote information terminal. On the basis of , more detailed supplementary annotations were made on the movement trajectory, so as to obtain the progress of the entire rescue process. To sum up, it can be seen that this scheme has good adaptability to the field environment, and enables search and rescue personnel to obtain information such as the location of emergency personnel faster and more accurately, which can provide technical support for improving rescue efficiency.

The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It will be understood that each flow and/or block in the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to the processor of a general purpose computer, special purpose computer, embedded processor or other programmable data processing device to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing device produce Means for implementing the functions specified in a flow or flow of a flowchart and/or a block or blocks of a block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory result in an article of manufacture comprising instruction means, the instructions The apparatus implements the functions specified in the flow or flow of the flowcharts and/or the block or blocks of the block diagrams.

These computer program instructions can also be loaded on a computer or other programmable data processing device to cause a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process such that The instructions provide steps for implementing the functions specified in the flow or blocks of the flowcharts and/or the block or blocks of the block diagrams.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be Modifications or equivalent replacements are made to the specific embodiments of the present invention, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention shall be included within the protection scope of the claims of the present invention.

Claims (9)

1. a LoRa multi-hop communication method for field rescue, the method adopts rescue node, network access node and LoRa gateway, rescue node and network access node all belong to mobile terminal and utilize LoRa communication module to communicate, it is characterized in that, network access node Join the LoRaWAN network where the LoRa gateway is located, and set the network access node in the Class C working mode, and communicate with the rescue node in the Receive Window RX2 window specified by LoRaWAN, the rescue node, the network access node and the LoRa gateway. A LoRa multi-hop communication network is formed; the rescue node and the network access node use the same preamble at the physical layer; The rescue node periodically sends data packets, and forwards the data packets received from other rescue nodes according to the set rules. After receiving the data packets sent by the rescue node, the network access node does not forward to other The rescue node or the network access node, the network access node forwards the received data packets to the LoRa gateway through the LoRaWAN network according to the communication format specified by LoRaWAN; The rescue node processes the received data packets according to the following steps: Step 1, after receiving the data packet, the rescue node checks whether the duplicate data packet is received, and if the duplicate data packet is received, discarding processing is performed and the remaining steps are not performed, otherwise, the received data packet is recorded and goes to step 2; Step 2, check whether the rescue node itself is in the distress call mode or the search and rescue mode, if it is in the distress call mode, perform step 3, and if it is in the search and rescue mode, perform step 4; Step 3, check the working mode of the node in the data packet, if it is in the search and rescue mode, present the current location information and the current time in the data packet to the rescuer to inform the rescuer of the location, and then perform step 5, if it is in the rescue mode, directly Execute step 5; Step 4, check the working mode of the node in the data group, if it is in the call for help mode, display all the location information and the acquisition time in the data group locally, which is used to instruct the search and rescue personnel to go to the rescue, and then go to step 5, if it is in the search and rescue mode, execute directly step 5; Step 5: Check whether the data packet reaches the maximum number of forwarding times, if not, reduce the remaining number of forwarding times in the data packet by 1, and then use broadcast to forward to other rescue nodes and network access nodes, otherwise it is directly discarded. 2. the LoRa multi-hop communication method for field rescue according to claim 1, is characterized in that, described data packet is made up of two parts of control field and data load; The control field includes the source device ID, the forwarding device ID, the data packet sequence number SEQ and the maximum forwarding times TTL; the data load includes the node working mode, the user identity, the location information obtained for the first time after the node is powered on, and the current time, current Location information and current time. 3. The LoRa multi-hop communication method for field rescue according to claim 2, wherein the rescue node is provided with two working modes: a distress call mode and a search and rescue mode. 4. A LoRa multi-hop communication system for field rescue is characterized in that, comprising rescue node terminal, network access node terminal, LoRa gateway, server and telematics terminal; The network access node terminal, the LoRa gateway and the server form a LoRaWAN network based on the LoRaWAN protocol, and the rescue node terminal, the network access node terminal and the LoRa gateway form a LoRa multi-hop communication network; The rescue node terminal and the network access node terminal include a microprocessor module, a LoRa communication module, a display module, a Beidou positioning module and a power supply module, and the LoRa communication module, the display module, the Beidou positioning module and the power supply module are all connected with the microprocessor. connected to the device module; The rescue node terminal processes the received data packets according to the following steps: Step 1: After receiving the data packet, the rescue node terminal checks whether it has received the duplicate data packet. If it receives the duplicate data packet, it discards the data packet and does not perform the remaining steps. Otherwise, the received data packet is recorded and goes to step 2. ; Step 2, check whether the rescue node terminal itself is in the distress call mode or the search and rescue mode, if it is in the distress call mode, perform step 3, and if it is in the search and rescue mode, perform step 4; Step 3, check the working mode of the rescue node terminal in the data packet, if it is in the search and rescue mode, present the current location information and the current time in the data packet to the rescuer, which is used to inform the rescuer of the location, and then go to step 5, if it is in the rescue mode. Then directly execute step 5; Step 4: Check the working mode of the rescue node terminal in the data packet. If it is in the distress mode, display all the location information and the acquisition time in the data packet on the rescue node terminal, which is used to instruct the search and rescue personnel to go to the rescue, and then go to Step 5. If In search and rescue mode, step 5 is directly executed; Step 5, check whether the data packet reaches the maximum number of forwarding times, if not, reduce the remaining number of forwarding times in the data packet by 1, and use broadcast to forward to other rescue node terminals and network access node terminals, otherwise directly discard; The network access node terminal joins the LoRaWAN network where the LoRa gateway is located, and the network access node terminal is set in the Class C working mode, and communicates with the rescue node terminal in the Receive Window RX2 window specified by LoRaWAN. Communicate through a multi-hop protocol; the rescue node terminal and the network access node terminal use the same preamble at the physical layer; The server manages the LoRaWAN network and provides MQTT subscription services, the remote information terminal communicates with the server through the Internet, and subscribes to the data packets sent by the network node terminal through the MQTT protocol, and realizes the rescue process by extracting the load content of the data packets. Display and processing of relevant geographic location information in . 5. a kind of LoRa multi-hop communication system for field rescue according to claim 4, is characterized in that, described rescue node terminal periodically sends data packet, and the data packet received from other rescue node terminals is set according to After receiving the data packet sent by the rescue node terminal, the network access node terminal will not forward it to other rescue node terminals or the network access node terminal, and the network access node terminal will receive the data packet. According to the communication format specified by LoRaWAN, it is forwarded to the LoRa gateway through the LoRaWAN network. 6. a kind of LoRa multi-hop communication system for field rescue according to claim 4, is characterized in that, described network access node terminal periodically sends data packet to described server through LoRaWAN network, the load of data packet is included The following location-related information is included: the current location information and current time of the network access node terminal. 7. The LoRa multi-hop communication system for field rescue according to claim 4, wherein the rescue node terminal is provided with two working modes: a distress call mode and a search and rescue mode. 8. a kind of LoRa multi-hop communication system for field rescue according to claim 4, is characterized in that, described telematics terminal obtains the movement track of rescuer or rescuer according to the following steps: Step A, the telematics terminal obtains the data packets of all rescue node terminals held by a certain rescuer or a certain rescuer from the server; Step B, according to the time when the rescue node terminal obtained the location information for the first time after the rescue node terminal is powered on included in the data packet, according to the order of time from small to large, sort all rescue node terminals corresponding to the time; In step C, the movement track of the rescuer or the rescuer is obtained according to the current position of the rescue node terminal contained in the data packet. 9. A LoRa multi-hop communication system for field rescue according to claim 4, wherein the rescue node terminal periodically sends data packets, wherein the period T=T ₀ +rand() seconds, T ₀ For a fixed length of time, rand() is a random number between 0-1.

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