CN113507703A - LoRa multi-hop communication method and system for field rescue - Google Patents

LoRa multi-hop communication method and system for field rescue Download PDF

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Publication number
CN113507703A
CN113507703A CN202110759924.XA CN202110759924A CN113507703A CN 113507703 A CN113507703 A CN 113507703A CN 202110759924 A CN202110759924 A CN 202110759924A CN 113507703 A CN113507703 A CN 113507703A
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rescue
node
data packet
network access
terminal
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CN113507703B (en
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赵洪钢
张宇恒
哈革列孜.欧拉
陈小宇
时晨
贾艳艳
寇鹏飞
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National University of Defense Technology
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/90—Services for handling of emergency or hazardous situations, e.g. earthquake and tsunami warning systems [ETWS]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/02—Services making use of location information
    • H04W4/029—Location-based management or tracking services
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W40/00—Communication routing or communication path finding
    • H04W40/02—Communication route or path selection, e.g. power-based or shortest path routing
    • H04W40/22—Communication route or path selection, e.g. power-based or shortest path routing using selective relaying for reaching a BTS [Base Transceiver Station] or an access point
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

Abstract

The invention discloses a LoRa multi-hop communication method and a system for field rescue, wherein the system comprises 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 is added into a LoRaWAN network where the LoRa gateway is located, the network access node terminal works in a Class C mode and communicates with the rescue node terminal at a Receive Window RX2 Window specified by the LoRaWAN, and 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 the LoRa multi-hop communication system for field rescue have better field adaptability, can enable search and rescue personnel to acquire information such as the position of the rescue calling personnel more quickly and accurately, and upload the position information of the search and rescue personnel in time, thereby providing guarantee for improving rescue efficiency and guaranteeing the safety of the search and rescue personnel.

Description

LoRa multi-hop communication method and system for field rescue
Technical Field
The invention belongs to the field of Internet of things, and particularly relates to a LoRa multi-hop communication method and system for field rescue.
Background
When people carry out field exploration, expedition, camping or traveling, the people need to call for help to the outside in time once danger occurs due to complex environments such as deserts, swamps or forests and the like and abnormal changes of climate and the like; however, due to factors such as complex environment, the rescue team can hardly acquire information such as the current position and the moving track of the person calling for help at the first time, and the gold rescue time is delayed. The internet of things is typically characterized in that a wireless self-organizing network system is formed by the sensing nodes deployed in a monitoring area, so that information of a sensing object in a network coverage area can be sensed, collected and processed cooperatively and sent to an observer. It can be expected that with the rapid development of the internet of things technology and the wide application in various fields, the environmental practicability of the field rescue system is improved by utilizing the characteristics of wireless self-organization, cooperative sensing and the like of the internet of things technology, so that search and rescue personnel can acquire information such as the position of a help-calling person more quickly and accurately, and the search and rescue personnel will become an inevitable development trend of the field rescue system research.
At present, many rescue systems are designed in such a way that intelligent wearable devices are used for monitoring the physical state, the geographic position and other information of a person calling for help, and then the monitoring information is uploaded to a network help seeking platform through technologies such as GPRS (general packet radio service); however, due to the limited (or even no) number of base station facilities in the field environment, the rescue system architecture described above is only suitable for a small portion of application scenarios. In addition, the partial rescue system utilizes the Internet of things technologies such as a Beidou satellite navigation system, ZigBee and the like to design and realize a field rescue system; however, the inherent disadvantages of high energy consumption, high cost, low cruising ability and the like of the satellite navigation system and the defects of short transmission distance, weak penetration ability and the like of the ZigBee technology restrict the further development of the rescue systems.
At present, internet of things technologies such as Zigbee, WIFI and GPRS are applied to various rescue systems, but because the transmission distance of traditional internet of things technologies such as Zigbee, WIFI and GPRS is limited and the power consumption is large, the application range in a field environment is very small, and the popularization and application are difficult to realize under the conditions of wide search and rescue regions and complex environment; compared with the defects existing when the traditional Internet of things technologies such as ZigBee, WIFI and GPRS are applied to a field rescue system, a new Internet of things technology-LoRa (Long Range) technology proposed in 2013 adopts a spread spectrum communication mode, the communication distance of the new Internet of things technology can reach 15 kilometers (in an open environment) due to the link budget as high as 157db, the receiving current of the new Internet of things technology is only 10mA, the sleeping current of the new Internet of things technology is only 200nA, the service life of a battery can be greatly prolonged, the problem that the search and rescue range of the existing rescue system is small is favorably solved, and the long-time operation of equipment in the field is guaranteed.
LoRaWAN is a set of protocol standards which are provided by LoRa alliance based on LoRa physical layer transmission technology and mainly comprise an MAC layer, adopts single-hop and star network architecture, is flexible in network deployment, and contributes to rapid popularization of the LoRa technology. However, in recent years, with low-power Wide-Area Network (LPWAN) technology represented by LoRa, the low-power Wide-Area Network (LPWAN) technology is increasingly applied in complex environments such as field environment rescue, underground pipe Network monitoring, intelligent building meter reading, underground car factory management and the like, some defects in the LoRa application process are gradually revealed, that is, single-hop and star-type Network architectures adopted by LoRa are deployed, and still face problems of large path loss and the like in scenes with many obstacles and the like, and many researchers have started research on LoRa multi-hop communication technology.
Therefore, the LoRa multi-hop communication technology is used for designing and realizing the field rescue system, the complex environment adaptability of the field rescue system is greatly improved, and a brand new thought is provided for improving the field rescue efficiency.
Disclosure of Invention
Different from the prior many achievements on how to use a routing protocol for multi-hop communication between LoRa terminals, the invention provides a LoRa multi-hop communication method and system for field rescue, aiming at the current research situation that most of LoRa terminal products are developed based on LoRaWAN specifications and LoRaWAN only supports single-hop communication, and the LoRa multi-hop communication method and system have good popularization and application advantages.
The core idea of the LoRa multi-hop communication method provided by the invention is as follows: the method comprises the steps that a network access node added into the LoRaWAN network is placed in a Class C working mode, the network access node is communicated with other rescue nodes in a Receive Window RX2 Window specified by the LoRaWAN, the network access node and the rescue nodes are communicated with each other according to a multi-hop communication protocol designed in the text, and therefore the rescue nodes, the network access node and a LoRa gateway form the LoRa multi-hop communication network.
The technical scheme provided by the invention is as follows:
on one hand, the LoRa multi-hop communication method for field rescue utilizes a network access node to join a LoRaWAN network where a LoRa gateway is located, the network access node is set in a Class C working mode and communicates with a rescue node in a Receive Window RX2 Window specified by the LoRaWAN, and the rescue node, the network access node and the LoRa gateway form the LoRa multi-hop communication network; the rescue node and the network access node adopt the same lead code on a physical layer;
the rescue nodes periodically send data packets and forward the data packets received from other rescue nodes according to a set rule, and the network access node forwards the received data packets to the LoRa gateway through the LoRaWAN network according to a communication format specified by the LoRaWAN.
The rescue node and the network access node belong to the mobile terminal, the rescue node is used for sending and receiving rescue information, and the network access node is used for forwarding the rescue information; after receiving the data packet sent by the rescue node, the network access node does not forward the data packet to other rescue nodes or the network access node, that is, the data packet only goes up to the gateway through the network access node and then is 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 comprises a source equipment ID, a forwarding equipment ID, a data packet sequence number SEQ and a maximum forwarding time TTL; the data load comprises a node working mode, a user identity, position information and current time obtained for the first time after the node is started, current position information and current time.
Further, the rescue node is provided with two working modes: a distress 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 a data packet, the rescue node checks whether the repeated data packet is received, if so, the data packet is discarded and the remaining steps are not executed, otherwise, the received data packet is recorded and the step 2 is executed;
step 2, checking whether the rescue node is in a distress call mode or a search and rescue mode, if the rescue node is in the distress call mode, executing step 3, and if the rescue node is in the search and rescue mode, executing step 4;
step 3, checking a node working mode in the data packet, if the node working mode is the search and rescue mode, presenting current position information and current time in the data packet to a person calling for help for informing the position of the search and rescue person, then executing step 5, and if the node working mode is the search and rescue mode, directly executing step 5;
step 4, checking a node working mode in the data packet, if the node working mode is the distress call mode, locally displaying all position information and acquisition time in the data packet for indicating search and rescue personnel to go to rescue, then executing step 5, and if the node working mode is the rescue call mode, directly executing step 5;
and 5, checking whether the data packet reaches the maximum forwarding times, if not, subtracting 1 from the residual forwarding times in the data packet, and then forwarding the data packet to other rescue nodes and network access nodes by using broadcasting, otherwise, directly discarding the data packet.
On the other hand, the LoRa multi-hop communication system for field rescue comprises a rescue node terminal, a network access node terminal, a LoRa gateway, a server and a remote information terminal;
the network access node terminal, the LoRa gateway and the server form a LoRaWAN network based on a 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 respectively comprise a microprocessor module, an 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 module;
the network access node terminal is added into a LoRaWAN network where a LoRa gateway is located, the network access node terminal is set in a Class C working mode and communicates with the rescue node terminal at a Receive Window RX2 Window specified by the LoRaWAN, and the rescue node terminals communicate with each other through a multi-hop protocol; the rescue node terminal and the network access node terminal adopt the same lead code on a physical layer;
the server manages the LoRaWAN network and provides MQTT subscription service, the remote information terminal access node terminal is communicated with the server through the Internet, subscribes data packets sent by the access node terminal through an MQTT protocol, and the display and processing of relevant geographic position information in the rescue process are realized by extracting the load content of the data packets.
The system has better field adaptability, can enable search and rescue personnel to acquire information such as the position of the help-calling personnel more quickly and accurately, and uploads the position information of the search and rescue personnel in time, so that technical support is provided for improving the rescue efficiency and guaranteeing the safety of the search and rescue personnel.
The research of multihop is carried out based on LoRaWAN standard, the utilization of equipment in each scene after molding is convenient, and the real mutual interconnection is realized. For example, as the LoRaWAN product is gradually applied to scenes such as forest parks and camping bases, a terminal added to the LoRaWAN network may be used for managing devices such as street lamps; by the method, after the existing LoRa terminal software program is simply upgraded, the existing LoRaWAN system can have an additional rescue function, namely, the rescue node, the existing LoRa terminal and the LoRa gateway are allowed to form a multi-hop network, so that the transmission of various rescue information is completed.
Further, the rescue node terminal periodically sends data packets and forwards the data packets received from other rescue node terminals according to a set rule, the network access node terminal receives the data packets sent by the rescue node terminal and then does not forward the data packets 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 a communication format specified by the LoRaWAN.
Further, the network access node terminal periodically sends a data packet to the server through the LoRaWAN network, where the following location-related information in a load packet of the data packet: and the current position information and the current time of the network access node terminal.
Further, the rescue node terminal is provided with two working modes: the rescue node terminal processes the received data packet according to the following steps:
step 1, after receiving a data packet, the rescue node terminal checks whether the repeated data packet is received, if so, the data packet is discarded and the remaining steps are not executed, otherwise, the received data packet is recorded and the step 2 is executed;
step 2, checking whether the rescue node terminal is in a distress call mode or a search and rescue mode, if the rescue node terminal is in the distress call mode, executing step 3, and if the rescue node terminal is in the search and rescue mode, executing step 4;
step 3, checking the working mode of the rescue node terminal in the data packet, if the data packet is in the search and rescue mode, presenting the current position information and the current time in the data packet to a person calling for help for informing the position of the search and rescue person, then executing step 5, and if the data packet is in the search and rescue mode, directly executing step 5;
step 4, checking the working mode of the rescue node terminal in the data packet, displaying all position information and acquisition time in the data packet on the rescue node terminal for indicating search and rescue personnel to go to rescue if the rescue node terminal is in the distress call mode, then executing step 5, and directly executing step 5 if the rescue node terminal is in the search and rescue mode;
and 5, checking whether the data packet reaches the maximum forwarding times, if not, subtracting 1 from the residual forwarding times in the data packet, and then forwarding the data packet to other rescue node terminals and network access node terminals by using broadcasting, otherwise, directly discarding the data packet.
Further, the remote information terminal obtains the moving track of the person calling for help or the person searching for help according to the following steps:
step A, the remote information terminal acquires data packets of all rescue node terminals held by a certain person calling for help or a certain person searching for help from the server;
b, according to the time for obtaining the position information for the first time after the rescue node terminals included in the data packet are started, sequencing all the rescue node terminals corresponding to the time in the sequence from small to large;
and step C, obtaining the moving track of the person calling for help or the person searching for help according to the current position of the rescue node terminal contained in the data packet.
Further, the rescue node terminal periodically transmits data packets, wherein the period T is T0+ rand () seconds, T0For a fixed length of time, rand () is a random number between 0-1.
Advantageous effects
Compared with the prior art, the invention has the following technical effects:
according to the technical scheme, the advantages of wide coverage, large connection, low power consumption, low cost and the like of the LoRa technology are fully utilized, meanwhile, the working mode and the communication mode of the network access node are set, and the designed multi-hop communication protocol is combined, so that the LoRa multi-hop communication capacity is expanded, the problems that the transmission performance is unreliable and the like in outdoor scenes with more obstacles and the like can be well solved, the system can have better outdoor environment adaptability, search and rescue personnel can acquire information such as the position of the rescue calling personnel more quickly and accurately, and technical support is provided for improving the rescue efficiency.
The technical scheme of the invention expands LoRa multi-hop communication capacity on the basis of LoRaWAN network, which not only can make full use of the mature technology of LoRaWAN network and improve the overall reliability of the system; the existing LoRaWAN terminal products, server systems and other rich resources in the market can be fully utilized, the design of the rescue node, the network access node, the server and the App is completed through simple expansion, the research and development period of related products is shortened, and the product cost is reduced.
(III) the rescue node provided by the technical scheme of the invention can be used by the help caller and the search and rescue personnel together, so that the search and rescue personnel can send information such as self position to the server in time in the search process, and technical support is provided for guaranteeing the safety of the search and rescue personnel in the rescue process.
Drawings
Fig. 1 is an architecture diagram of a field rescue system based on LoRa multi-hop communication according to an embodiment of the present invention;
FIG. 2 is a format of a data packet periodically transmitted by a rescue node in an embodiment of the present invention;
FIG. 3 is a complex scenario in which a rescue process test is located;
FIG. 4 shows the actual measurement positions of the gateway, the network access node and the rescue node in the rescue process test;
fig. 5 shows the progress of rescue that the rescue commander can grasp.
Detailed Description
The present invention will be explained in further detail with reference to examples.
The invention can improve the complex environment adaptability of the field rescue system and improve the field rescue efficiency, and the basic implementation thought is as follows: when the field help-calling personnel find that the personnel are in dangerous conditions, the help-calling personnel can send out a help-calling signal by utilizing the portable rescue node terminal and deploy the help-calling node along the way in the self-rescue process; search and rescue personnel firstly utilize a network access node terminal, a LoRa gateway and a server to form a LoRaWAN network, then carry rescue node terminals to carry out search and rescue, and deploy the rescue node terminals along the way in the search and rescue process; the remote information terminal acquires data of the rescue node terminal, the network access node terminal and the LoRa gateway through the access server, and displays various information in the rescue process on the electronic map, so that rescue commanders can conveniently master the situation in time and take corresponding measures; because the rescue node terminal and the network access node terminal can form a LoRa multi-hop communication network, after the rescue node terminal carried by a search and rescue worker is successfully communicated with any one rescue node terminal carried by the search and rescue worker or deployed along the way, the search and rescue worker can know the current position and the moving track of the search and rescue worker through the rescue node terminal carried by the search and rescue worker, and the rescue commander can check all the moving tracks of the search and rescue worker through a remote information terminal such as a PC, a tablet or a mobile phone, so that the rescue progress condition can be mastered timely and comprehensively; because the removal orbit of search and rescue personnel also can present on information terminal, consequently when search and rescue personnel self met danger, can make other search and rescue personnel expand the rescue to oneself rapidly through switching to the mode of calling for help, further promoted entire system's rescue effect.
The present invention is not limited to the following embodiments, and all equivalent changes based on the technical solutions of the present invention fall within the protection scope of the present invention.
The embodiment provides a LoRa multi-hop communication method for field rescue, wherein a LoRaWAN network where a LoRa gateway is located is added by using a network access node, the network access node is set in a Class C working mode and is communicated with a rescue node in a Receive Window RX2 Window specified by the LoRaWAN, and the rescue node, the network access node and the LoRa gateway form the LoRa multi-hop communication network; the rescue node and the network access node adopt the same lead code on a physical layer;
the rescue nodes periodically send data packets, the data packets received from other rescue nodes are forwarded to the network access node by broadcasting according to set rules, and the network access node forwards the received data packets to the LoRa gateway through the LoRaWAN according to a communication format specified by the LoRaWAN.
The rescue node periodically sends a data packet, wherein the data packet is composed of a control field and a data load, the control field comprises a Source device ID (Source _ ID), a forwarding device ID (Forward _ ID), a data packet sequence number SEQ and a maximum forwarding Time TTL, the data load comprises a node working Mode (Mode), a user identity (Person _ ID), Position information (Position _0) and Time (Time _0) obtained for the first Time after the node is started, current Position information (Position _ N) and current Time (Time _ N), and the data load is specifically shown in FIG. 2;
the rescue node is provided with two working modes: a distress 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 a data packet, the rescue node checks whether the repeated data packet is received, if so, the data packet is discarded and the remaining steps are not executed, otherwise, the received data packet is recorded and the step 2 is executed;
step 2, checking whether the rescue node is in a distress call mode or a search and rescue mode, if the rescue node is in the distress call mode, executing step 3, and if the rescue node is in the search and rescue mode, executing step 4;
step 3, checking a node working mode in the data packet, if the node working mode is the search and rescue mode, presenting current position information and current time in the data packet to a person calling for help for informing the position of the search and rescue person, then executing step 5, and if the node working mode is the search and rescue mode, directly executing step 5;
step 4, checking a node working mode in the data packet, if the node working mode is the distress call mode, locally displaying all position information and acquisition time in the data packet for indicating search and rescue personnel to go to rescue, then executing step 5, and if the node working mode is the rescue call mode, directly executing step 5;
and 5, checking whether the data packet reaches the maximum forwarding times, if not, subtracting 1 from the residual forwarding times in the data packet, and then forwarding the data packet to other rescue nodes and network access nodes by using broadcasting, otherwise, directly discarding the data packet.
The rescue node and the network access node belong to the mobile terminal, the rescue node is used for sending and receiving rescue information, and the network access node is used for forwarding the rescue information; after receiving the data packet sent by the rescue node, the network access node does not forward the data packet to other call-for-help nodes or the network access node, that is, the data packet only goes up to the gateway through the network access node and then is not sent to other network access nodes or rescue nodes through the network access node.
The embodiment also provides an LoRa multi-hop communication system for field rescue, which comprises a rescue node terminal, a network access node terminal, an LoRa gateway, a server and a remote information terminal, as shown in fig. 1;
the network access node terminal, the LoRa gateway and the server form a LoRaWAN network based on a 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 respectively comprise a microprocessor module, an 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 module;
the network access node terminal is added into a LoRaWAN network where a LoRa gateway is located, is set in a Class C working mode and communicates with the rescue node at a Receive Window RX2 Window specified by the LoRaWAN; the rescue node terminal and the network access node terminal adopt the same lead code on a physical layer;
the server manages the LoRaWAN network and provides MQTT subscription service, the remote information terminal is communicated with the server through the Internet, subscribes data packets sent by the network access node terminal through an MQTT protocol, and the display and processing of relevant geographic position information in the rescue process are realized by extracting the load content of the data packets.
The system has better field adaptability, can enable search and rescue personnel to acquire information such as the position of the help-calling personnel more quickly and accurately, and uploads the position information of the search and rescue personnel in time, so that technical support is provided for improving the rescue efficiency and guaranteeing the safety of the search and rescue personnel.
The research of multihop is carried out based on LoRaWAN standard, the utilization of equipment in each scene after molding is convenient, and the real mutual interconnection is realized. For example, as the LoRaWAN product is gradually applied to scenes such as forest parks and camping bases, a terminal added to the LoRaWAN network may be used for managing devices such as street lamps; by the method, after the existing LoRa terminal software program is simply upgraded, the existing LoRaWAN system can have an additional rescue function, namely, the rescue node, the existing LoRa terminal and the LoRa gateway are allowed to form a multi-hop network, so that the transmission of various rescue information is completed.
The rescue node terminal periodically sends data packets and forwards the data packets received from other rescue node terminals according to a set rule, the network access node terminal does not forward the data packets to other rescue node terminals or the network access node terminal after receiving the data packets sent by the rescue node terminal, and the network access node terminal forwards the received data packets to the LoRa gateway through the LoRaWAN according to a communication format specified by the LoRaWAN.
The network access node terminal periodically sends data packets to the server through a LoRaWAN network, and the load of the data packets comprises the following position related information in a packet: and the current position information and the current time of the network access node terminal.
The rescue node terminal is provided with two working modes: the rescue node terminal processes the received data packet according to the following steps:
step 1, after receiving a data packet, the rescue node terminal checks whether the repeated data packet is received, if so, the data packet is discarded and the remaining steps are not executed, otherwise, the received data packet is recorded and the step 2 is executed;
step 2, checking whether the rescue node terminal is in a distress call mode or a search and rescue mode, if the rescue node terminal is in the distress call mode, executing step 3, and if the rescue node terminal is in the search and rescue mode, executing step 4;
step 3, checking the working mode of the rescue node terminal in the data packet, if the data packet is in the search and rescue mode, presenting the current position information and the current time in the data packet to a person calling for help for informing the position of the search and rescue person, then executing step 5, and if the data packet is in the search and rescue mode, directly executing step 5;
step 4, checking the working mode of the rescue node terminal in the data packet, displaying all position information and acquisition time in the data packet on the rescue node terminal for indicating search and rescue personnel to go to rescue if the rescue node terminal is in the distress call mode, then executing step 5, and directly executing step 5 if the rescue node terminal is in the search and rescue mode;
and 5, checking whether the data packet reaches the maximum forwarding times, if not, subtracting 1 from the residual forwarding times in the data packet, and then forwarding the data packet to other rescue node terminals and network access node terminals by using broadcasting, otherwise, directly discarding the data packet.
The remote information terminal obtains the moving track of the person calling for help or the person searching for help according to the following steps:
step A, the remote information terminal acquires data packets of all rescue node terminals held by a certain person calling for help or a certain person searching for help from the server;
b, according to the time for obtaining the position information for the first time after the rescue node terminals included in the data packet are started, sequencing all the rescue node terminals corresponding to the time in the sequence from small to large;
and step C, obtaining the moving track of the person calling for help or the person searching for help according to the current position of the rescue node terminal contained in the data packet.
The rescue node terminal periodically sends data packets, wherein the period T is T0+ rand () seconds, T0For a fixed length of time, rand () is a random number between 0-1.
In order to verify the effectiveness of the scheme, the rescue process is tested.
The rescue process test is carried out in the scene containing a large number of various obstacles such as houses, trees and the like shown in fig. 3, so that the scheme is proved to be capable of realizing LoRa multi-hop communication and providing technical support for guaranteeing the safety of search and rescue personnel while improving the rescue efficiency.
In the experimental process, the node 2 is a rescue node carried by a person calling for help, the node 1 is a network access node which is placed in a range of normal communication with a gateway, and the node 2 and the node 1 cannot communicate; the node 4 is a rescue node carried by search and rescue personnel. In the testing process, the gateway is erected on a small soil slope with the height of 2 meters, the heights of the antennas of the network access node and the rescue node do not exceed 1 meter, and the gateway is randomly deployed at the wall corner of a short house, the bottom of a line pole and the like. In the rescue process, the actual measurement positions of the gateway, the network access node and the rescue node are shown in fig. 4.
After the experiment begins, the rescue node 2 carried by the person calling for help can not communicate with the node 1, when the rescue node 4 carried by the person calling for help enters the communication range of the node 2, the node 2 realizes communication with the node 1 through forwarding of the node 4, so that multi-hop communication among the node 2, the node 4, the node 1 and the gateway is realized, information such as the position of the person calling for help is uploaded to the server in time, and relevant information such as the position and identification of the node in the whole rescue process is displayed on the remote information terminal. The rescue commander accurately and timely acquires the moving tracks of the help caller and the search and rescue personnel according to the related information displayed on the remote information terminal, so that the rescue progress condition can be timely and comprehensively mastered; fig. 5 shows that the rescue commander performs more detailed supplementary labeling on the movement track on the basis of information display of the remote information terminal, so as to obtain the progress of the whole rescue process. Therefore, the scheme has better field environment adaptability, enables search and rescue personnel to acquire information such as the position of the help calling personnel more quickly and accurately, and 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 application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

Claims (9)

1. A LoRa multi-hop communication method for field rescue adopts a rescue node, a network access node and a LoRa gateway, wherein the rescue node and the network access node belong to mobile terminals and communicate by utilizing a LoRa communication module, and the method is characterized in that the network access node is added into a LoRaWAN network where the LoRa gateway is located, the network access node is arranged in a Class C working mode and communicates with the rescue node at a Receive Window RX2 Window specified by the LoRaWAN, and the rescue node, the network access node and the LoRa gateway form the LoRa multi-hop communication network; the rescue node and the network access node adopt the same lead code on a physical layer;
the rescue nodes periodically send data packets and forward the data packets received from other rescue nodes according to a set rule, the network access node receives the data packets sent by the rescue nodes and then does not forward the data packets to other rescue nodes or the network access node, and the network access node forwards the received data packets to the LoRa gateway through the LoRaWAN according to a communication format specified by the LoRaWAN.
2. The LoRa multi-hop communication method for outdoor rescue according to claim 1, wherein the data packet is composed of a control field and a data load;
the control field comprises a source equipment ID, a forwarding equipment ID, a data packet sequence number SEQ and a maximum forwarding time TTL; the data load comprises a node working mode, a user identity, position information and current time obtained for the first time after the node is started, current position information and current time.
3. The LoRa multi-hop communication method for outdoor rescue according to claim 2, characterized in that the rescue node is provided with two working modes: a distress 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 a data packet, the rescue node checks whether the repeated data packet is received, if so, the data packet is discarded and the remaining steps are not executed, otherwise, the received data packet is recorded and the step 2 is executed;
step 2, checking whether the rescue node is in a distress call mode or a search and rescue mode, if the rescue node is in the distress call mode, executing step 3, and if the rescue node is in the search and rescue mode, executing step 4;
step 3, checking a node working mode in the data packet, if the node working mode is the search and rescue mode, presenting current position information and current time in the data packet to a person calling for help for informing the position of the search and rescue person, then executing step 5, and if the node working mode is the search and rescue mode, directly executing step 5;
step 4, checking a node working mode in the data packet, if the node working mode is the distress call mode, locally displaying all position information and acquisition time in the data packet for indicating search and rescue personnel to go to rescue, then executing step 5, and if the node working mode is the rescue call mode, directly executing step 5;
and 5, checking whether the data packet reaches the maximum forwarding times, if not, subtracting 1 from the residual forwarding times in the data packet, and then forwarding the data packet to other rescue nodes and network access nodes by using broadcasting, otherwise, directly discarding the data packet.
4. A LoRa multi-hop communication system for field rescue is characterized by comprising a rescue node terminal, a network access node terminal, a LoRa gateway, a server and a remote information terminal;
the network access node terminal, the LoRa gateway and the server form a LoRaWAN network based on a 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 respectively comprise a microprocessor module, an 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 module;
the network access node terminal is added into a LoRaWAN network where a LoRa gateway is located, the network access node terminal is set in a Class C working mode and communicates with the rescue node terminal at a Receive Window RX2 Window specified by the LoRaWAN, and the rescue node terminals communicate with each other through a multi-hop protocol; the rescue node terminal and the network access node terminal adopt the same lead code on a physical layer;
the server manages the LoRaWAN network and provides MQTT subscription service, the remote information terminal is communicated with the server through the Internet, subscribes data packets sent by the network access node terminal through an MQTT protocol, and the display and processing of relevant geographic position information in the rescue process are realized by extracting the load content of the data packets.
5. The LoRa multi-hop communication system for field rescue according to claim 4, wherein the rescue node terminal periodically sends data packets and forwards the data packets received from other rescue node terminals according to a set rule, the network access node terminal receives the data packets sent by the rescue node terminal and then does not forward the data packets 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 a LoRaWAN network according to a communication format specified by the LoRaWAN.
6. The LoRa multi-hop communication system for outdoor rescue according to claim 4, wherein the network access node terminal periodically sends data packets to the server through the LoRaWAN network, and the data packets include the following position-related information in their load packets: and the current position information and the current time of the network access node terminal.
7. The LoRa multi-hop communication system for outdoor rescue according to claim 4, wherein the rescue node terminal is provided with two working modes: the rescue node terminal processes the received data packet according to the following steps:
step 1, after receiving a data packet, the rescue node terminal checks whether the repeated data packet is received, if so, the data packet is discarded and the remaining steps are not executed, otherwise, the received data packet is recorded and the step 2 is executed;
step 2, checking whether the rescue node terminal is in a distress call mode or a search and rescue mode, if the rescue node terminal is in the distress call mode, executing step 3, and if the rescue node terminal is in the search and rescue mode, executing step 4;
step 3, checking the working mode of the rescue node terminal in the data packet, if the data packet is in the search and rescue mode, presenting the current position information and the current time in the data packet to a person calling for help for informing the position of the search and rescue person, then executing step 5, and if the data packet is in the search and rescue mode, directly executing step 5;
step 4, checking the working mode of the rescue node terminal in the data packet, displaying all position information and acquisition time in the data packet on the rescue node terminal for indicating search and rescue personnel to go to rescue if the rescue node terminal is in the distress call mode, then executing step 5, and directly executing step 5 if the rescue node terminal is in the search and rescue mode;
and 5, checking whether the data packet reaches the maximum forwarding times, if not, subtracting 1 from the residual forwarding times in the data packet, and then forwarding the data packet to other rescue node terminals and network access node terminals by using broadcasting, otherwise, directly discarding the data packet.
8. The LoRa multi-hop communication system for field rescue according to claim 4, wherein the remote information terminal obtains the moving track of the person calling for help or the person searching for help according to the following steps:
step A, the remote information terminal acquires data packets of all rescue node terminals held by a certain person calling for help or a certain person searching for help from the server;
b, according to the time for obtaining the position information for the first time after the rescue node terminals included in the data packet are started, sequencing all the rescue node terminals corresponding to the time in the sequence from small to large;
and step C, obtaining the moving track of the person calling for help or the person searching for help according to the current position of the rescue node terminal contained in the data packet.
9. The LoRa multi-hop communication system for outdoor rescue according to claim 4, wherein the rescue node terminal periodically transmits data packets, wherein the period T is T0+ rand () seconds, T0For a fixed length of time, rand () is a random number between 0-1.
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