CN113824571B

CN113824571B - Agricultural thing networking that is fit for wisdom agricultural

Info

Publication number: CN113824571B
Application number: CN202111398274.7A
Authority: CN
Inventors: 李向阳; 哀薇
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-11-24
Filing date: 2021-11-24
Publication date: 2022-03-18
Anticipated expiration: 2041-11-24
Also published as: CN113824571A

Abstract

The agricultural Internet of things suitable for intelligent agriculture provided by the invention can be used for communicating the concentrator and the equipment according to the MAC address and communicating according to the equipment, so that the communication efficiency is greatly improved, and the number of nodes possibly contained in a LoRa network is increased. The communication process from the concentrator to the equipment adopts a superframe structure, and simultaneously supports time-driven and event-driven communication modes; the concentrator allocates a time slot to each equipment node in the time slot matrix, and the equipment nodes finish communication based on time drive in the time slot of the non-competitive period; if the communication is unsuccessful in the time slot, the communication can be carried out again in the time slot of the competition period in the superframe structure by adopting an event-driven mode, so that the reliability and the real-time performance of the communication are improved; the superframe structure also reduces the communication energy consumption of the device nodes. The application layer of the agricultural Internet of things adopts a data packet format of a reserved time execution command.

Description

Agricultural thing networking that is fit for wisdom agricultural

Technical Field

The invention belongs to the field of Internet of things, and particularly relates to an agricultural Internet of things suitable for intelligent agriculture.

Background

The agriculture has the characteristics of wide operation area, low technical level of personnel and the like, the characteristics require the intelligent agriculture to have large coverage, low operation cost and small maintenance workload, and meanwhile, the agricultural automation network generally has low requirements on communication speed and real-time performance and has strict requirements on equipment electric energy consumption. The application of high technology to intelligent agriculture is an effective means for solving agricultural production problems including the above problems.

Disclosure of Invention

In order to solve the technical problems, the invention provides a technical scheme of an agricultural internet of things suitable for intelligent agriculture, and the technical problems are solved.

The invention discloses an agricultural Internet of things suitable for intelligent agriculture, and a hardware structure of the agricultural Internet of things comprises: the system comprises equipment nodes, a concentrator and a computing center; the architecture of the agricultural Internet of things comprises a physical layer, a data link layer and an application layer, wherein the physical layer adopts a physical layer protocol of LoRa; the data link layer adopts a data packet format with a superframe structure and checks and encapsulates data;

the data packet format of the superframe structure comprises: the synchronization frame is the beginning of a data packet of the superframe structure; the following is a non-contention period, followed by a contention period, and finally a frame interval;

when the concentrator issues commands to the equipment nodes, the same commands transmitted to different equipment at different times can be executed at the same time at the appointed time by adopting a command mode of advance reservation.

In some embodiments, the non-contention period is a period of data frame communication based on a time-driven communication period, consisting of a number of time-driven period slots, each time-driven period slot being allocated to one device node, the device node completing one communication interaction with the concentrator in the time-driven period slot.

In some embodiments, the contention period is a period of data frame communication based on an event driven communication period, which is made up of several event driven period time slots, which are contended by the device nodes through a signal activity detection approach.

In some embodiments, the specific manner in which the device nodes contend for the time slot of the event driven period by means of signal activity detection includes:

the first mode is as follows: the method comprises the steps that equipment nodes which do not enter a field network apply for joining the field network to a concentrator, the equipment nodes calculate a data frame communication time period based on an event-driven communication time period according to data of a beacon frame after receiving the beacon frame, and then apply for distributing a time-driven time period time slot in the data frame communication time period based on the time-driven communication time period to the concentrator in a competition mode in the data frame communication time period based on the event-driven communication time period;

the second mode is as follows: when the communication of the equipment node in the time-driven communication time slot is unsuccessful, the equipment node competes for the event-driven time slot again in a signal activity detection mode and carries out secondary communication with the concentrator in the event-driven time slot;

the third mode is as follows: when the time slot of the event-driven period distributed by the equipment node is not reached, the equipment node generates an emergency event, the equipment node competes for the time slot of the event-driven period in a signal activity detection mode, and the equipment node communicates with the concentrator in the period based on the event drive.

In some embodiments, each superframe-structured packet only allocates time-driven time slots to a certain number of device nodes, and a plurality of consecutive superframe-structured packets are used to complete time-driven time slot allocation for all the device nodes, so as to form a time-driven time slot matrix, wherein a column of the time-driven time slot matrix is a time-driven time slot in a superframe-structured packet, and a row of the time-driven time slot matrix is a superframe-structured packet sequence.

In some embodiments, the device node is in a power saving sleep state and the concentrator is in an idle state in the frame interval.

In some embodiments, the frame structure of the synchronization frame comprises:

frame control words, the length of the frame, the field network address, the address of the concentrator, the address of the equipment node, the maximum number of superframes, the time slot duration, the number of time slots in the time-driven period, the number of time slots in the event-driven period, the number of time slots in the dormant period, the line number of the frame, the transmitting power, the working frequency, the current time, the operating time, the operation code, the data object value and the CRC check.

In some embodiments, the device node address specifically includes: short address and class address;

the equipment node selects one concentrator with good signal strength from a plurality of concentrators as a management node of the equipment node, applies for joining the network to the concentrator through a long address, namely a physical address of LoRa, the concentrator can allocate a short address to the equipment node, and then the class address is allocated according to the type of the equipment node.

In some embodiments, the device node can only be assigned a short address, and the device node can be assigned multiple class addresses.

In some embodiments, the concentrator has two groups of antennas, and performs communication of different frequency channels simultaneously, and performs mutual backup, and the device node switches between two communication channels, and the concentrator searches an idle channel with less interference as a candidate channel in an idle time, and switches to the candidate channel with a high signal-to-noise ratio when the signal-to-noise ratio in use exceeds an acceptable range.

Therefore, the proposal of the invention can be seen,

(1) compared with the agricultural Internet of things which simply adopts public networks such as 4G, NB-IOT and the like, the agricultural Internet of things based on the LoRa technology has lower operation cost and manufacturing cost, has small dependence on public network coverage, and can be deployed in places such as 4G, NB-IOT and the like where public wireless network signals are not good or do not exist.

(2) By adopting a superframe structure and a communication mode based on time and events, the communication requirements of periodic communication and emergencies of agricultural production on communication can be better met, and meanwhile, a new node can automatically join in a network, so that the use and maintenance are convenient.

(3) And an asymmetrical energy management mode is adopted, so that the power consumption of the equipment node is saved, the battery capacity of the equipment node and the area of the solar panel can be reduced, and the total cost of the system can be reduced.

(4) The communication mode of the class address is increased, the communication traffic is reduced, and the node capacity is improved.

In summary, the scheme provided by the invention can perform communication between the concentrator and the equipment according to the MAC address, and can also perform communication according to the equipment class, thereby greatly improving the communication efficiency and increasing the number of nodes possibly contained in the LoRa network. The communication process from the concentrator to the equipment adopts a superframe structure, and simultaneously supports time-driven and event-driven communication modes; the concentrator allocates a time slot to each equipment node in the time slot matrix, and the equipment nodes finish communication based on time drive in the time slot of the non-competitive period; if the communication is unsuccessful in the time slot, the communication can be carried out again in the time slot of the competition period in the superframe structure by adopting an event-driven mode, so that the reliability and the real-time performance of the communication are improved; the superframe structure also reduces the communication energy consumption of the device nodes. The application layer of the agricultural Internet of things adopts a data packet format of the reserved time execution command, so that the synchronization performance of the equipment node for executing the task is improved, and the reliability is also improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a structural diagram of an agricultural internet of things suitable for smart agriculture according to an embodiment of the invention;

FIG. 2 is a general block diagram of a device node according to an embodiment of the present invention;

FIG. 3 is a schematic block diagram of a concentrator in accordance with an embodiment of the present invention;

fig. 4 is an architecture diagram of an agricultural internet of things according to an embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention discloses an agricultural Internet of things suitable for intelligent agriculture. Fig. 1 is a structural diagram of an agricultural internet of things suitable for smart agriculture according to an embodiment of the present invention, as shown in fig. 1,

the hardware structure of agricultural thing networking includes: the system comprises equipment nodes, a concentrator and a computing center; as shown in fig. 4, the architecture 100 of the agricultural internet of things includes a physical layer 101, a data link layer 102, and an application layer 103, where the physical layer 101 employs a physical layer protocol of LoRa; the data link layer 102 adopts a data packet format with a superframe structure, and checks and encapsulates data; the application layer 103 adopts the contents of the prior art.

In some embodiments, physical layer 101 is based on the LoRa physical layer, implemented with SX 1278;

the data packet format of the superframe structure comprises: the synchronization frame is the beginning of a data packet of the superframe structure; the following is a non-contention period, followed by a contention period, and finally a frame interval, as shown in table 1.

TABLE 1

In some embodiments, the method is divided into three levels, namely a site level (equipment node), a zone controller (concentrator) and a computing center (cloud platform). The concentrator and the on-site equipment nodes carry out networking communication through an on-site network; the concentrator exchanges data with a cloud platform of a computer center through an NB-IoT or 4G/2G network, when no cloud platform or public wireless network exists, the concentrator can also be connected with a mobile phone or a portable computer through WiFi, data acquisition and control of field equipment are completed through the mobile phone, dependence on the public wireless network is reduced, and the concentrator is particularly suitable for agricultural automation of remote and remote areas.

The field network of the agricultural Internet of things adopts a LoRa physical layer, and has the characteristics of long transmission distance and large coverage area. The equipment nodes adopt 1 antenna, and the concentrator adopts 2 antennas; the concentrator can work in two frequency bands at the same time, and the equipment node can select the working frequency band according to the signal intensity; if one frequency band is seriously interfered, the equipment node can also be added into another frequency band for communication, so that the communication reliability is improved. The concentrator continuously detects the interference and conflict conditions of LoRa working channels (470 MHz-510 MHz) in the electromagnetic environment during the idle time of communication, selects the idle channels as candidate working channels, and stably switches to new working channels once the existing working channels have strong interference and influence on normal communication, and broadcasts to the equipment nodes by using another frequency band, and the equipment nodes gradually move to the new working channels.

Fig. 2 is a general block diagram of a device node consisting of a power supply circuit, a low power consumption MCU machine peripheral circuit, a human-machine interface, a sensor circuit, an actuator circuit, and a LoRa transceiver machine peripheral circuit, some nodes may have only sensors and no actuators, and some nodes may have only actuators and no sensors. The power supply circuit consists of a solar battery, a lithium iron phosphate rechargeable battery and a voltage conversion circuit and provides electric energy for the whole system. The man-machine interface consists of keys and a digital tube, can be used for on-site debugging and checking working state and parameter configuration, and can also be completed by the concentrator in a remote mode. The human-computer interface is in a closed state when not used so as to reduce power consumption. The LoRa transceiver and the peripheral circuit thereof are connected with the MCU through the SPI interface, the LoRa transceiver adopts SX1278 and works at the frequency of 470 MHz-510 MHz (CN 470-510), and when receiving a data frame, the MCU is awakened through interruption, and the data receiving and answering are completed. STM32L010C6 is selected for use to the low-power consumption singlechip, and the singlechip is except accomplishing functions such as communication, data acquisition, control execution and human-computer interface, still carries out energy management to every module, and only these modules are in operating condition just supplies power to reduce the consumption. For example, when a temperature and humidity sensor needs to collect temperature and humidity, the sensor is powered on, data is collected after the data is stable, and a power supply of the sensor is turned off after the data is collected; for another example, when the dc gear motor as the actuator needs to work, the MCU controls the power supply to supply power to the motor driving chip, and controls the operating voltage of the dc gear motor through PWM to control the rotation speed thereof, and after the adjustment of the valve opening and the like is completed, the motor stops working, and then the power supply of the driving chip is turned off.

Fig. 3 is a schematic structure diagram of a concentrator, which is composed of a power supply circuit, an MCU and its peripheral circuits, a wireless public network module, a Flash memory, an LoRa transceiver circuit 1, and an LoRa transceiver circuit 2. The power supply circuit adopts a solar power supply, storage and conversion circuit which is similar to the equipment node but has larger power; four 21700 batteries of 12.8V (3.2V each) and 4500mAh lithium iron phosphate batteries are adopted, and a charging chip adopts BQ 24707A; the direct current gear motor directly adopts 12.8V power supply, and 12.8V battery voltage becomes 3.6V through chip DC/DC and supplies power for NB-IoT module, becomes 3.3V and supplies power for other circuits such as ESP32 module, MCU, loRa chip. The concentrator has two sets of loRa transceiver circuits, can realize two equipment node communications simultaneously, increases communication capacity, has also increased the reliability of communication. The Flash memory adopts W25Q128, system working parameters are stored in the Flash memory and are connected with the MCU through the SPI, the system working parameters are stored in two different storage areas in the Flash memory, backup is carried out mutually, meanwhile, one storage area is also stored in the SRAM of the MCU, and the frequency of reading and writing Flash is reduced. The MCU selects STM32L4R5VGT6 and has a 640KB memory, in general application, more than one day of data can be temporarily stored, and the data can be instantly stored in a data center through a public network during normal work; when there is no public network, it can be stored in Flash storage, and the user communicates with the concentrator through WiFi using a mobile phone or a laptop to transmit data. The MCU and the LoRa transceiver communicate through a USART (configured as an SPI working mode) interface, and communicate with public wireless network modules such as NB-IoT/4G/2G through a USART (configured as a UART working mode), and the WiFi module is connected through a UART structure and is selected from ESP 32-WROOM-32E.

the second mode is as follows: when the communication of the equipment node in the time-driven communication time slot is unsuccessful, the equipment node competes for the event-driven time slot again in a signal activity detection mode, and carries out secondary communication with the concentrator in the event-driven time slot, so that the reliability and the real-time performance of the communication are improved;

the third mode is as follows: when the time slot of the event-driven period distributed by the equipment node is not reached, the equipment node generates an emergency, the equipment node competes for the time slot of the event-driven period in a signal activity detection mode, and communicates with the concentrator in the period based on the event drive, so that the real-time response capability is improved.

In some embodiments, the device node is in a power-saving sleep state during the frame interval, and the concentrator is in an idle state, where idle means not communicating with the device node, but the concentrator searches for other possible operating channels through the antenna, evaluates the electromagnetic environment, and searches for an idle channel for future use; when the idle channel is searched, the channel is used as a standby channel, and if the signal-to-noise ratio of the channel which is working at present is not high and normal communication is influenced, the concentrator broadcasts a switching notice through a beacon frame and switches to the channel in the standby channel according to a certain time sequence.

In some embodiments, as shown in tables 2 (a) - (c), the frame structure of the synchronization frame comprises:

TABLE 2 (a)

TABLE 2 (b)

TABLE 2 (c)

In some embodiments, the device node can only be assigned one short address, but the device node can be assigned multiple class addresses.

Specifically, for synchronization of the superframe and broadcast of the network parameters, when the device node receives the frame, it indicates that the superframe starts. Meanwhile, as shown in tables 2 (a) - (c), (1) the address of the field network may exist in a large area, a device node covered by multiple concentrators may receive beacon frames of two or more concentrators, the device node may select one concentrator with good signal strength as its own management node, and apply for joining the network to the concentrator through a long address (8 bytes of a physical address of LoRa), the concentrator may assign a short address (2 bytes) to the concentrator, and may then assign a class address (2 bytes) according to the type of the device node, each device node may only be assigned a short address, but may assign multiple class addresses, and the short address of the concentrator is fixed to 0xACC 5; (2) superframe structure and network parameters including maximum superframe number, slot duration, time-driven period slot number, event-driven period slot number, and dormant period number, which describe the size of the slot matrix and the duration of each period; (3) the current line number (the line number of the current frame), the line number of the current frame in the time slot matrix and the column number are obtained by calculating according to the time slot after the current frame is finished; (4) the device node can estimate the link power loss in the communication process according to the received signal strength, so that the transmitting power of the device node is adjusted, reliable communication is ensured, and energy is saved; the working frequency is 2 bytes, which represents the working frequency range in 2 CN470-510 at present; (5) the current time, which is in two formats, year/month/day/week and hour/minute/second/hundredth of second, is determined by the frame control word. (6) The meanings of the operation time, the operation code, the data object code, and the data object value are the same as those of tables 3 (a), 3 (b), 4 (a), and 4 (b), which will be described later, and this is a communication method by carrying the contents of the data frame in the synchronization beacon frame; by adopting the method, the communication efficiency of the concentrator sent to the equipment node is improved. The device address of the synchronous beacon frame can be a short address or a similar address, data can be sent to all device nodes of the same type through the similar address, the same content is sent for multiple times due to the periodicity of the beacon frame, the operation time (uniqueness is achieved in one day) is adopted for distinguishing, and the reliability is improved.

In some embodiments, tables 3 (a) - (b) and tables 4 (a) - (b) are typical data frame formats that a device node sends to a concentrator and a concentrator sends to a device node, respectively, and in particular what data frame is determined by the frame control word. The method comprises the following steps: (1) the length of the frame indicates the byte number of the subsequent data, the value is changed due to the difference of the object data values, but the value does not exceed 56 bytes at most, and the characteristic that the short frame is more suitable for agricultural measurement and control data is adopted; (2) the field network address is the address of the network managed by the added concentrator, the device node address can be the 8-byte device physical address or the 2-byte short address or the 2-byte class address, and the specific address type is determined by the frame control word; (3) the operation time, the operation code, the data object code and the data object value give the content and time of the data object operation; for example, the operation time: 15 hours, 32 minutes, 23 seconds, 40 sub-seconds (1/100 seconds), opcode: writing (controlling opening), data object encoding: valve 1, valve 2, data object value: 30 (valve opening 30%), 60 (valve opening 60%); the method organizes the attributes or states of the equipment nodes and the operations on the attributes or states by adopting an object-oriented method, and encapsulates the operation time together to form an atomic transaction, thereby not only facilitating the understanding and the application of users, but also reducing the transmission times of data frames; because the operation time can be the future time, the reservation type transaction processing mode can increase the synchronism among the equipment nodes and reduce the transmission delay caused by over concentration of transaction communication; (4) the intensity of the received signal, which is sent to the concentrator by the equipment node and is the intensity of the received signal of the synchronous frame of the concentrator received by the equipment node, the concentrator adjusts the transmitting power of the concentrator according to the intensity of the received signal, all the equipment nodes in the jurisdiction area can reliably receive the data frame, and the feedback mechanism ensures the reliability of communication; (5) CRC adopts 4-byte check code to ensure the correctness of data in data frame, which is important for measurement and control system, and the other method for ensuring reliability is that the same command adopts multiple transmissions of the same data frame.

The acknowledgement frames and request frames in the data frames between the device node and the concentrator are also encapsulated in the format of tables 3 (a) - (b) and tables 4 (a) - (b), except that the frame control word and data object are encoded differently. The consistent processing method simplifies the software program design of the node, a plurality of data frames can be confirmed by one-time communication (a plurality of data frame numbers and receiving states are added in the data object value, the 'operating time' can be used as the data frame number), and the real-time information such as the received signal strength and the like can be carried in each communication, so that the communication traffic is reduced.

TABLE 3 (a)

TABLE 3 (b)

TABLE 4 (a)

TABLE 4 (b)

Specifically, when the device node joins the network, after power-on and system initialization are completed, scanning is performed according to a preset possible channel, a concentrator broadcast Beacon frame is searched, if a plurality of concentrators are found, the concentrator with the maximum signal intensity is selected, and accordingly the transmission power of the concentrator can be adjusted. And then, communicating with the concentrator in the competition time slot, informing the concentrator of the parameters of the concentrator, distributing a preset time slot by the concentrator, and finishing the joining of the equipment node into the network. Since there are a large number of device nodes, it is not possible nor necessary to assign a time slot to each node in the time slot of a superframe. Each data packet of the super frame structure only distributes time driving period time slots to a certain number of equipment nodes, and the time driving period time slot distribution of all the equipment nodes is completed by adopting a plurality of data packets of the continuous super frame structure, so that a time driving period time slot matrix is formed, the row of the time driving period time slot matrix is a time driving period time slot in one data packet of the super frame structure, and the row of the time driving period time slot matrix is a data packet sequence of the super frame structure. For example, if there are 1000 device nodes and a superframe has 20 time slots, 50 superframes are required to allocate a time slot to each device node, and this is a (50 × 20) matrix, where each element position in the matrix is a node number indicating the position of the device node in the time slot. The superframes are circularly transmitted according to the matrix rows, the row number of the frame in the synchronous beacon frame of each superframe indicates the row number of the frame in the time slot matrix, and the column number is calculated by the delay time after the synchronous frame starts.

After the equipment joins the network, the equipment node periodically sends the measured data of the working state, the battery capacity and the like of the equipment node to the concentrator according to a preset time slot or in a competition time slot stage, and the concentrator sends the measured data to the cloud or the data center through NB-IoT. And a real-time data table is established in a memory for each terminal node in the concentrator, and historical data is stored in Flash in a database mode. The user can communicate with the concentrator through a mobile phone or a computer in a WiFi mode, and can complete equipment data transmission and working parameter configuration in the concentrator, so that the system can realize local automation even without a public network (4G or NB-IoT and the like) and complete all work of the system.

The invention adopts a LoRa modulation and demodulation technology to realize a physical layer of an agricultural Internet of things, designs a data link layer and an application layer which are suitable for agricultural working characteristics on the basis, comprehensively utilizes a time slot-based time driving and competition mechanism-based event driving mode from a concentrator of the Internet of things to terminal equipment in a communication mode, has wide coverage range, can maintain normal power supply of the equipment through solar energy, and particularly accords with the agricultural working characteristics.

It should be noted that the technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, however, as long as there is no contradiction between the combinations of the technical features, the scope of the present description should be considered. The above examples only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. An agricultural thing networking that is fit for wisdom agriculture, the hardware architecture of agricultural thing networking includes: the device node and the concentrator are linked with the computing center; the architecture of the agricultural Internet of things comprises a physical layer, a data link layer and an application layer, and is characterized in that the physical layer adopts a LoRa physical layer protocol; the data link layer adopts a data packet format with a superframe structure and checks and encapsulates data;

the concentrator comprises a Flash memory for storing system working parameters, a real-time data table is established in a memory for each terminal node in the concentrator, historical data is stored in the Flash memory in a database mode, and when the concentrator issues commands to the equipment nodes, the concentrator adopts a command mode of advance reservation so that the same commands transmitted to different equipment at different times can be executed at the same time at the appointed time;

wherein:

each data packet of the super frame structure only distributes time driving period time slots to a certain number of equipment nodes, and the time driving period time slot distribution of all the equipment nodes is completed by adopting a plurality of data packets of continuous super frame structures, so that a time driving period time slot matrix is formed, the row of the time driving period time slot matrix is a time driving period time slot in one data packet of the super frame structure, and the row of the time driving period time slot matrix is a data packet sequence of the super frame structure;

the frame structure of the synchronization frame includes:

frame control words, the length of the frame, the field network address, the address of a concentrator, the address of a device node, the maximum number of superframes, time slot duration, the number of time slots in a time-driven period, the number of time slots in an event-driven period, the number of time slots in a dormant period, the line number of the frame, transmission power, working frequency, current time, operating time, an operation code, a data object value and CRC (cyclic redundancy check); the frame line number in the sync frame of each superframe indicates the line number of the frame in the slot matrix.

2. The agriculture internet of things suitable for smart agriculture of claim 1, wherein the non-contention period is a data frame communication period based on a time-driven communication period, and is composed of a plurality of time-driven period time slots, each time-driven period time slot is allocated to a device node, and the device node completes one communication interaction with the concentrator in the time-driven period time slot.

3. The internet of things of agriculture for smart agriculture as claimed in claim 2, wherein the contention period is a period of data frame communication based on an event-driven communication period, and is composed of a plurality of event-driven period time slots, and the device nodes compete for the event-driven period time slots by signal activity detection.

4. The internet of things of agriculture for smart agriculture of claim 3, wherein the device nodes compete for event-driven time slots by signal activity detection means in a specific manner comprising:

the first mode is as follows: the method comprises the steps that equipment nodes which do not enter a field network apply for joining the field network to a concentrator, the equipment nodes calculate a data frame communication time interval based on an event-driven communication time interval according to data of a synchronous frame after receiving the synchronous frame, and then apply for distributing a time-driven time interval slot in the data frame communication time interval based on the time-driven communication time interval to the concentrator in a competition mode in the data frame communication time interval based on the event-driven communication time interval;

5. The agricultural internet of things suitable for smart agriculture of claim 1, wherein the device nodes in the frame interval are in an energy-saving sleep state, and the concentrator is in an idle state.

6. The agricultural internet of things suitable for smart agriculture of claim 1, wherein the device node address specifically comprises: short address and class address;

the equipment node selects one concentrator with good signal strength from the plurality of concentrators as a management node of the equipment node, applies for joining the network to the concentrator through a physical address of LoRa serving as a long address, the concentrator allocates a short address to the equipment node, and then allocates a class address according to the type of the equipment node.

7. The agricultural internet of things suitable for smart agriculture of claim 6, wherein the equipment node can be assigned only one short address, and the equipment node can be assigned multiple class addresses.

8. The agriculture internet of things suitable for smart agriculture according to claim 1, wherein the concentrator has two sets of antennas, and communicates with different frequency channels simultaneously, and backs up each other, the device node switches between the two communication channels, the concentrator searches for an idle channel with less interference as a candidate channel during idle time, and switches to the candidate channel with high signal-to-noise ratio when the signal-to-noise ratio in use exceeds an acceptable range.