A remote meter reading communication method and communication module

Abstract

The invention relates to the technical field of remote meter reading, and discloses a remote meter reading communication method and a communication module. When a communication module reports measuring instrument data, if the connection between the communication module and a main station fails, the disconnected communication module broadcasts a session key frame to a radio frequency network. The session key frame is used to find a communication module in other communication modules of a normal communication network, and the communication module is used as a relay node to forward the measuring instrument data of the disconnected communication module to the main station, so that the method is suitable for harsh wireless data transmission environments.

Description

Technical Field

[0001] The present invention relates to the technical field of remote meter reading, and in particular to a remote meter reading communication method and a communication module. Background Art

[0002] At present, wired meter reading technology has problems such as complex wiring, long polling time, poor anti-interference ability, and high upgrade cost. With the development of network communication technology, wireless data transmission technology is gradually applied to remote meter reading technology.

[0003] With the rapid development of Internet of Things technology, communication modules based on LTE-Cat1 technology are increasingly used in the field of remote meter reading. At present, there is a great demand for this product in scenarios such as fee collection and energy efficiency management in universities, apartments, parks, and industries. However, in basements, closed spaces, and blind spots in buildings, the LTE-Cat1 signal quality is poor, and the communication module cannot establish a connection with the master station. Summary of the invention

[0004] In view of this, the present invention provides a remote meter reading communication method and a communication module to solve the problem that the communication module cannot establish a connection with a master station.

[0005] In the first aspect, the present invention provides a remote meter reading communication method, which is applied to a first communication module, and the first communication module is a communication module of a current node disconnected from a main station, and the method includes: when the first communication module reports measuring instrument data, the first communication module broadcasts a session key frame, and the session key frame is used by the second communication module to verify whether the session of the first communication module is legal; the second communication module is a communication module of other nodes; after the first communication module receives a forwarding license application frame, the first communication module selects a second communication module with the strongest signal and normal communication as a relay communication module, and the first communication module sends a forwarding license to the relay communication module; the forwarding license application frame is issued by the second communication module with normal communication; the forwarding license is used to allow the relay communication module to send the measuring instrument data received by the first communication module to the main station.

[0006] The disconnected communication module of the present invention broadcasts a session key frame to the radio frequency network. The session key frame is used to find a communication module in other communication modules with normal communication, and the communication module is used as a relay node to forward the measuring instrument data of the disconnected communication module to the system main station, so that it is suitable for harsh environments of wireless data transmission.

[0007] In an optional implementation, the frame format of the session key frame consists of a frame header, frame type, TTL value, source address, destination address, key, check code and frame tail in sequence; the source address in the session key frame is the Mac address of the disconnected communication module, and the destination address is the broadcast address.

[0008] In an optional embodiment, the process of the first communication module selecting the second communication module with the strongest signal and normal communication as the relay communication module includes: the first communication module extracts the signal strength and TTL value in each forwarding license application frame, and calculates the selection result corresponding to each forwarding license application frame; the second communication module corresponding to the selection result with the maximum value is used as the relay communication module;

[0009] The selection result is calculated by the following selection function:

[0010]

[0011] Where Relay(n) is the selection function, n=1,2,3…,N, N is the number of forwarding license application frames; RSSI LTE Signal strength in the forwarding license request frame; RSSI LoRa is the signal strength of the measuring instrument data received by the first communication module; a, b, c are weight factors of the selection function.

[0012] In a second aspect, the present invention provides a remote meter reading communication method, which is applied to a second communication module, and the second communication module is a communication module of other nodes. The method includes: when the second communication module receives a session key frame, the second communication module verifies the received session key frame, and when the session key frame is legal, the second communication module with normal communication sends a forwarding license application frame; the session key frame is sent by the first communication module, and the first communication module is a communication module that is disconnected from the current node and the main station; after the second communication module selected as the relay communication module receives the forwarding license, the relay communication module forwards the measuring instrument data received by the first communication module to the main station; the forwarding license is sent by the first communication module.

[0013] The present invention performs verification after the second communication module receives the session key frame to prevent interference and attack from other network devices in the application environment, thereby ensuring the security and robustness of the network communication.

[0014] In an optional embodiment, the process of the second communication module verifying the received session key frame includes: the second communication module extracts the TTL value and the key in the session key frame, the extracted key is the first key, and the second communication module converts the key stored in itself through a specific algorithm to obtain the second key; when the first key is inconsistent with the second key, the second communication module determines that the session key frame is illegal and discards it.

[0015] In an optional implementation, the process of the second communication module verifying the received session key frame also includes: when the first key is consistent with the second key, the second communication module determines whether the TTL value is 0; when the TTL value is 0, the second communication module determines that the session key frame is illegal and discards it.

[0016] In an optional implementation, the process of the second communication module verifying the received session key frame also includes: when the TTL value is not 0, the second communication module determines that the session key frame is legal and queries the cache table to confirm whether the session key frame has been forwarded; when the session key frame has not been forwarded, the second communication module subtracts 1 from the TTL value in the received session key data frame and forwards it to the second communication module of other nodes through the radio frequency network.

[0017] In an optional implementation, the frame format of the forwarded license application frame consists of a frame header, frame type, TTL value, source address, destination address, key, signal strength, checksum and frame tail sequence; the destination address of the forwarded license application frame is the source address of the received session key frame.

[0018] In an optional embodiment, the remote meter reading communication method also includes: after the relay communication module receives the data frame forwarded by the first communication module, it traverses the forwarding list to confirm whether the source address of the data frame is in the forwarding list; when the source address of the data frame is in the forwarding list, the relay communication module reports the data frame to the main station; the data frame includes the measuring instrument data of the first communication module.

[0019] In an optional implementation, the remote meter reading communication method further includes: after the relay communication module receives the forwarding license, the relay communication module adds the Mac address of the first communication module to the forwarding list; after the relay communication module receives the cancellation of the forwarding license sent by the first communication module, the relay communication module deletes the Mac address of the first communication module in the forwarding list.

[0020] In a third aspect, the present invention provides a remote meter reading communication module, based on the remote meter reading communication method of the first aspect, the second aspect and any optional implementation manner thereof, the remote meter reading communication module comprises: a communication module, a radio frequency module and an interface circuit, wherein a first end of the communication module is connected to a master station through an LTE network, a second end of the communication module is connected to a first end of the radio frequency module, and a third end of the communication module is connected to a first end of the interface circuit; the communication module is an OpenCPU communication module; a second end of the radio frequency module is connected to a second end of a radio frequency module in another communication module; a second end of the interface circuit is connected to a measuring instrument; when the communication module of the current node is disconnected from the master station, the communication module of the current node is the first communication module, The communication modules of other nodes are second communication modules; the communication module of the first communication module is the first communication module, and the radio frequency module of the first communication module is the first radio frequency module; the communication module of the second communication module is the second communication module, and the radio frequency module of the second communication module is the second radio frequency module; the first communication module is connected to communicate with at least one second communication module through the first radio frequency module and the second radio frequency module of the second communication module, the first communication module uses the remote meter reading communication method of the first aspect and any optional implementation manner thereof to find the relay communication module, and the relay communication module sends the measuring instrument data received by the first communication module to the main station; the second communication module responds to the first communication module using the remote meter reading communication method of the second aspect and any optional implementation manner thereof.

[0021] In an optional embodiment, the remote meter reading communication module also includes: a power supply module and an indication circuit, wherein the first end of the power supply module inputs the supply voltage, the second end of the power supply module is connected to the fourth end of the communication module, and the power supply module is used to convert the supply voltage to power the communication module and the indication circuit; the indication circuit is connected to the fifth end of the communication module and the fifth end of the power supply module, and the indication circuit is used to indicate the working status of the communication module. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 is a flow chart of a remote meter reading communication method according to an embodiment of the present invention;

[0024] Figure 2 is a schematic structural diagram of a remote meter reading communication module according to an embodiment of the present invention;

[0025] Figure 3is a flow chart of another remote meter reading communication method according to an embodiment of the present invention;

[0026] Figure 4 is a flow chart of another remote meter reading communication method according to an embodiment of the present invention;

[0027] Figure 5 is a flow chart of another remote meter reading communication method according to an embodiment of the present invention;

[0028] Figure 6 is a composition diagram of a remote meter reading communication module according to an embodiment of the present invention;

[0029] Figure 7 is a structural schematic diagram of an LTE-Cat1 communication module according to an embodiment of the present invention;

[0030] Figure 8 is a schematic diagram of the structure of a LoRa radio frequency module according to an embodiment of the present invention;

[0031] Fig. 9 is a schematic structural diagram of a power module according to an embodiment of the present invention;

[0032] Fig.10 is a schematic diagram of the structure of an LED indicator light according to an embodiment of the present invention;

[0033] Fig.11 Schematic diagram of the structure of the interface circuit of the embodiment of the present invention. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0035] According to an embodiment of the present invention, a remote meter reading communication method embodiment is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical sequence is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0036] The radio frequency network includes multiple communication nodes, each of which includes a communication module. Communication is established between the communication modules, and communication is also established between the communication modules and the master station. Each communication module is used to receive the measurement data of the measuring instrument and send the measurement data to the master station at a regular time. However, there may be a communication disconnection between the communication module and the master station, so that the master station cannot observe the measurement data in real time. Based on this, a remote meter reading communication method is provided in this embodiment, which is applied to a first communication module. The first communication module is a communication module that is disconnected from the current node and the master station, such as Figure 1 As shown, the method includes:

[0037] Step S11: When the first communication module reports the measuring instrument data, the first communication module broadcasts a session key frame, and the session key frame is used by the second communication module to verify whether the session of the first communication module is legal; the second communication module is the communication module of other nodes.

[0038] Specifically, the communication module structure is as follows: Figure 2 As shown in the figure, the communication module adopts the OpenCPU mode, which is an application mode that uses the LTE-Cat1 communication module as the main processor. It does not require an external MCU, and the corresponding power supply and peripheral devices can naturally be saved. This method can simplify the user's development process for communication terminals and streamline the hardware structure design, thereby meeting customer requirements in terms of cost, power consumption, security, etc.

[0039] like Figure 2 As shown, the communication module is composed of LTE-Cat1 communication module, LoRa radio frequency communication module, power module, interface circuit, operation status indication circuit and other parts. Since the internal storage space of LTE-Cat1 communication module is sufficient to store relevant data in the embodiment, the off-chip storage circuit part is omitted. The communication module communicates with the measuring instrument through the uart serial port in the downlink, and the uplink communication mainly uploads data to the system master station through the LTE network.

[0040] Specifically, after the communication module is successfully connected to the system master station, it periodically reports the measuring instrument data and receives the instructions issued by the system master station in real time. At the same time, the LoRa radio frequency module receives the LoRa network data in real time and performs relevant response processing. There is no primary or secondary distinction between LoRa radio frequency modules, and the communication protocol adopts a private protocol. The LoRa network adopts a Mesh network, and the entire network can be localized. The LoRa frame TTL (Time To Live) is set to 5.

[0041] Specifically, due to factors such as the environment and interference in which the communication module is located, it is impossible to establish a connection with the system master station. This module can be called a non-connection module, abbreviated as a disc module, that is, a first communication module. Figure 3As shown, this type of disc module needs to find a relay node through the Lora network to report the relevant data of this base table to the system master station, that is, the disc module will broadcast a session key frame through the RF network, and the session key frame is used to find a communication module among other communication modules in the RF network, and use the communication module as a relay node to forward the measurement instrument data of the disconnected communication module to the system master station.

[0042] Optionally, the frame format of the session key frame consists of a frame header, a frame type, a TTL value, a source address, a destination address, a key, a checksum and a frame tail in sequence; the source address in the session key frame is the Mac address of the disconnected communication module, and the destination address is a broadcast address.

[0043] Exemplarily, the disc module broadcasts the session key frame to the LoRa network. The frame format is: frame header (1 byte) + frame type (1 byte) + TTL (1 byte) + source address (6 bytes) + destination address (6 bytes) + key (4 bytes) + check (2 bytes) + frame tail (1 byte). The source address in the session key frame is the Mac address of the disc communication module (the communication address of the base table), and the destination address is: FF FF FF FF FF FF is the broadcast address.

[0044] Step S12: After the first communication module receives the forwarding license application frame, the first communication module selects the second communication module with the strongest signal and normal communication as the relay communication module, and the first communication module sends a forwarding license to the relay communication module; the forwarding license application frame is sent by the second communication module with normal communication; the forwarding license is used to allow the relay communication module to send the measuring instrument data received by the first communication module to the main station.

[0045] Specifically, when the second communication module receives the session key frame, in order to prevent interference and attacks from other LoRa network devices in the application environment and ensure the security and robustness of the LoRa network communication, the second communication module needs to verify the session key frame. After the verification is passed, the second communication module sends a forwarding license application frame to the first communication module.

[0046] Specifically, in order to ensure that a disc module has only one relay node and does not cause multiple relay nodes to forward the data of the same disc module at the same time, the disc module needs to select the second communication module with the strongest signal as the relay node, and then send the measurement data to the master station through the relay node.

[0047] In some optional implementations, the process of the first communication module selecting the second communication module with the strongest signal and normal communication as the relay communication module includes:

[0048] (1) The first communication module extracts the signal strength and TTL value in each forwarding license application frame, and calculates the selection result corresponding to each forwarding license application frame;

[0049] (2) The second communication module corresponding to the selection result having the maximum value is used as a relay communication module;

[0050] The selection result is calculated by the following selection function:

[0051]

[0052] Where Relay(n) is the selection function, n=1,2,3…,N, N is the number of forwarding license application frames; RSSI LTE Signal strength in the forwarding license request frame; RSSI LoRa is the signal strength of the measuring instrument data received by the first communication module; a, b, c are weight factors of the selection function.

[0053] Specifically, after the disc module receives a forwarding license application frame, it extracts the signal strength RSSI in each frame. LTE and TTL, and also record the signal strength RSSI of the received data LoRa The n groups of data received are selected through the optimal relay node function Relay(n)=aRSSI LTE +bRSSI LoRa +cTTL calculates the best node as the relay node and sends a forwarding license to this node.

[0054] In this embodiment, a remote meter reading communication method is provided, which is applied to a second communication module, and the second communication module is a communication module of other nodes, such as Figure 4 As shown, the method includes:

[0055] Step S21: When the second communication module receives the session key frame, the second communication module verifies the received session key frame. When the session key frame is legal, the second communication module with normal communication sends a forwarding license application frame; the session key frame is sent by the first communication module, and the first communication module is the communication module that disconnects the current node from the main station.

[0056] Specifically, after the second communication module receives the session key frame, in order to prevent interference and attacks from other LoRa network devices in the application environment and ensure the security and robustness of the LoRa network communication, the second communication module needs to verify the session key frame.

[0057] Step S22: After the second communication module selected as the relay communication module receives the forwarding license, the relay communication module forwards the measuring instrument data received by the first communication module to the master station; the forwarding license is issued by the first communication module.

[0058] Specifically, after the first communication module receives the forwarding license application frame, the first communication module selects the second communication module with the strongest signal and normal communication as the relay communication module, and sends a forwarding license to the relay communication module, which is used to allow the relay communication module to forward measurement data.

[0059] In some optional implementations, the process of the second communication module verifying the received session key frame includes:

[0060] The second communication module extracts the TTL value and key in the session key frame. The extracted key is the first key. The second communication module converts the key stored in itself through a specific algorithm to obtain the second key. When the first key and the second key are inconsistent, the second communication module determines that the session key frame is illegal and discards it.

[0061] Optionally, when the first key is consistent with the second key, the second communication module determines whether the TTL value is 0; when the TTL value is 0, the second communication module determines that the session key frame is illegal and discards it.

[0062] Optionally, the process of the second communication module verifying the received session key frame also includes: when the TTL value is not 0, the second communication module determines that the session key frame is legal and queries the cache table to confirm whether the session key frame has been forwarded; when the session key frame has not been forwarded, the second communication module subtracts 1 from the TTL value in the received session key data frame and forwards it to the second communication module of other nodes through the radio frequency network.

[0063] Specifically, Figure 5As shown, after receiving this broadcast frame, other communication modules in the LoRa network first check the legitimacy of the frame. If the check fails, it is directly discarded. If the check passes and the destination address is the broadcast address FF FF FF FF FFFF, the frame type is sent by the disc module, and the TTL and key are extracted. The extracted key is referred to as key_A. The key key_B stored in itself is converted through a specific algorithm to obtain the key key_C. If the key key_A is inconsistent with the key key_C, the session key data frame is discarded. If the key key_A is consistent with the key key_C, it is determined whether the TTL value is 0. If it is 0, the frame is discarded without any processing. If it is not 0, the cache table is queried to see if the frame has been forwarded. Each communication module has a cache table set inside to cache the data forwarded in the LoRa network. If it has not been forwarded, the TTL value in the received session key data frame is reduced by 1 and forwarded through the LoRa network.

[0064] After the verification is passed, the second communication module detects its own LTE communication status. If the LTE network communication is normal, a forwarding license application frame is sent, along with the signal strength value of the LTE network.

[0065] Optionally, the frame format of the forwarded license application frame consists of a frame header, a frame type, a TTL value, a source address, a destination address, a key, a signal strength, a checksum and a frame tail sequence; the destination address of the forwarded license application frame is the source address of the received session key frame.

[0066] For example, the frame format of the forwarding license application frame is frame header (1 byte) + frame type (1 byte) + TTL (1 byte) + source address (6 bytes) + destination address (6 bytes) + key (4 bytes) + signal strength (2 bytes) + checksum (2 bytes) + frame tail (1 byte). The destination address is replaced with the source address of the received frame.

[0067] In some optional embodiments, the remote meter reading communication method also includes: after the relay communication module receives the data frame forwarded by the first communication module, it traverses the forwarding list to confirm whether the source address of the data frame is in the forwarding list; when the source address of the data frame is in the forwarding list, the relay communication module reports the data frame to the main station; the data frame includes the measuring instrument data of the first communication module.

[0068] In some optional embodiments, the remote meter reading communication method also includes: after the relay communication module receives the forwarding license, the relay communication module adds the Mac address of the first communication module to the forwarding list; after the relay communication module receives the cancel forwarding license sent by the first communication module, the relay communication module deletes the Mac address of the first communication module in the forwarding list.

[0069] In this embodiment, a remote meter reading communication module is provided, and a remote meter reading communication method based on the above embodiment and any optional implementation manner thereof is provided. Figure 6 As shown, the remote meter reading communication module includes: a communication module, a radio frequency module and an interface circuit. Figure 6 Two remote meter reading communication modules are taken as an example.

[0070] like Figure 6 As shown, the first end of the communication module is connected to the main station through the LTE network, the second end of the communication module is connected to the first end of the RF module, and the third end of the communication module is connected to the first end of the interface circuit; the communication module is an OpenCPU communication module; the second end of the RF module is connected to the second end of the RF module in other communication modules; and the second end of the interface circuit is connected to the measuring instrument.

[0071] Specifically, when the communication module of the current node is disconnected from the main station, the communication module of the current node is the first communication module, and the communication modules of other nodes are the second communication modules; the communication module of the first communication module is the first communication module, and the radio frequency module of the first communication module is the first radio frequency module; the communication module of the second communication module is the second communication module, and the radio frequency module of the second communication module is the second radio frequency module.

[0072] The first communication module is connected to the at least one second communication module through the first radio frequency module and the second radio frequency module of the second communication module. The first communication module uses the remote meter reading communication method of the above embodiment and any optional implementation method applied to the first communication module to find the relay communication module, and the relay communication module sends the measuring instrument data received by the first communication module to the main station.

[0073] The second communication module responds to the first communication module using the remote meter reading communication method of the above embodiment and any optional implementation manner applied to the second communication module.

[0074] In some optional embodiments, such as Figure 2 As shown, the remote meter reading communication module also includes: a power supply module and an indication circuit, wherein: Figure 2 The indication circuit in the example takes the LED indicator light as an example.

[0075] Specifically, the first end of the power module inputs the supply voltage, the second end of the power module is connected to the fourth end of the communication module, and the power module is used to convert the supply voltage to power the communication module and the indication circuit; the indication circuit is connected to the fifth end of the communication module and the fifth end of the power module, and the indication circuit is used to indicate the working status of the communication module.

[0076] like Figure 2As shown in the figure, the communication module consists of LTE-Cat1 communication module, LoRa radio frequency communication module, power module, interface circuit, operation status indication circuit, etc. The communication module communicates with the measuring instrument through the uart serial port in downlink, and the uplink communication mainly uploads data to the system master station through the LTE network.

[0077] For example, the circuit structure of the LTE-Cat1 communication module is as follows: Figure 7 As shown, since the internal storage space of the LTE-Cat1 communication module is sufficient to store the relevant data of this design, the off-chip storage circuit part is omitted.

[0078] For example, the circuit structure of the LoRa radio module is as follows: Figure 8 As shown, the use of LoRa radio frequency modules can improve the receiving sensitivity, reduce power consumption, and support parallel processing of multiple channels and multiple data rates, and the system capacity is large.

[0079] For example, the circuit structure of the power module is as follows: Fig. 9 As shown, the power supply module is composed of two DC-DC circuits, wherein U2 converts 12V voltage into 4V voltage, and U3 converts 4V voltage into 3.3V voltage.

[0080] For example, the circuit structure of the LED indicator light is as follows: Fig.10 As shown, D13 and D14 are both light emitting diodes, D13 is used to indicate the receiving state, and D14 is used to indicate the sending state.

[0081] For example, the circuit structure of the interface circuit is as follows: Fig.11 The RXD end of the interface circuit receives the data from the measuring instrument, and the TXD end reports the data to the system master station.

[0082] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A remote meter reading communication method, characterized in that: Applied to a first communication module, the first communication module is a communication module in which the current node is disconnected from the master station, the method includes: When the first communication module reports the measuring instrument data, the first communication module broadcasts a session key frame, and the session key frame is used by the second communication module to verify whether the session of the first communication module is legal; the second communication module is a communication module of other nodes; After the first communication module receives the forwarding license application frame, the first communication module selects the second communication module with the strongest signal and normal communication as the relay communication module, and the first communication module sends a forwarding license to the relay communication module; the forwarding license application frame is sent by the second communication module with normal communication; the forwarding license is used to allow the relay communication module to send the measuring instrument data received by the first communication module to the main station; The frame format of the session key frame consists of a frame header, a frame type, a TTL value, a source address, a destination address, a key, a checksum, and a frame tail sequence; The process in which the first communication module selects the second communication module with the strongest signal and normal communication as the relay communication module includes: the first communication module extracts the signal strength and TTL value in each forwarding license application frame, and calculates the selection result corresponding to each forwarding license application frame; and uses the second communication module corresponding to the selection result with the maximum value as the relay communication module; The selection result is calculated by the following selection function: Wherein, Relay(n) is a selection function, n=1,2,3…,N, N is the number of the forwarding license application frames; RSSI LTE Signal strength in the forwarding license application frame; RSSI LoRa is the signal strength of the measuring instrument data received by the first communication module; a, b, c are weight factors of the selected function; The second communication module extracts the TTL value and key in the session key frame. When the TTL value is not 0, the second communication module determines that the session key frame is legal and queries the cache table to confirm whether the session key frame has been forwarded. When the session key frame has not been forwarded, the second communication module subtracts 1 from the TTL value in the received session key data frame and forwards it to the second communication module of the other node through the radio frequency network.

2. The remote meter reading communication method according to claim 1, characterized in that: The source address in the session key frame is the Mac address of the disconnected communication module, and the destination address is the broadcast address.

3. A remote meter reading communication method, characterized in that: Applied to a second communication module, where the second communication module is a communication module of another node, the method includes: When the second communication module receives the session key frame, the second communication module verifies the received session key frame. When the session key frame is legal, the second communication module with normal communication sends a forwarding license application frame; the session key frame is sent by the first communication module, and the first communication module is the communication module of the current node disconnected from the master station; After the second communication module selected as the relay communication module receives the forwarding license, the relay communication module forwards the measuring instrument data received by the first communication module to the master station; the forwarding license is issued by the first communication module; The frame format of the session key frame consists of a frame header, a frame type, a TTL value, a source address, a destination address, a key, a checksum, and a frame tail sequence; The process in which the first communication module selects the second communication module with the strongest signal and normal communication as the relay communication module includes: the first communication module extracts the signal strength and TTL value in each forwarding license application frame, and calculates the selection result corresponding to each forwarding license application frame; and uses the second communication module corresponding to the selection result with the maximum value as the relay communication module; The selection result is calculated by the following selection function: Wherein, Relay(n) is a selection function, n=1,2,3…,N, N is the number of the forwarding license application frames; RSSI LTE Signal strength in the forwarding license application frame; RSSI LoRa is the signal strength of the measuring instrument data received by the first communication module; a, b, c are weight factors of the selected function; The second communication module extracts the TTL value and key in the session key frame. When the TTL value is not 0, the second communication module determines that the session key frame is legal and queries the cache table to confirm whether the session key frame has been forwarded. When the session key frame has not been forwarded, the second communication module subtracts 1 from the TTL value in the received session key data frame and forwards it to the second communication module of the other node through the radio frequency network.

4. The remote meter reading communication method according to claim 3, characterized in that: The process of the second communication module verifying the received session key frame includes: The second communication module extracts the TTL value and the key in the session key frame, the extracted key is the first key, and the second communication module converts the key stored in itself through a specific algorithm to obtain a second key; When the first key is inconsistent with the second key, the second communication module determines that the session key frame is illegal and discards it.

5. The remote meter reading communication method according to claim 4, characterized in that: The process of the second communication module verifying the received session key frame further includes: When the first key is consistent with the second key, the second communication module determines whether the TTL value is 0; When the TTL value is 0, the second communication module determines that the session key frame is illegal and discards it.

6. The remote meter reading communication method according to claim 3, characterized in that: The frame format of the forwarding license application frame consists of a frame header, a frame type, a TTL value, a source address, a destination address, a key, a signal strength, a check code, and a frame tail sequence; The destination address of the forwarded license application frame is the source address of the received session key frame.

7. The remote meter reading communication method according to claim 3, characterized in that: Also includes: After receiving the data frame forwarded by the first communication module, the relay communication module traverses the forwarding list to confirm whether the source address of the data frame is in the forwarding list; When the source address of the data frame is in the forwarding list, the relay communication module reports the data frame to the master station; The data frame includes measurement instrument data of the first communication module.

8. The remote meter reading communication method according to claim 3, characterized in that: Also includes: After the relay communication module receives the forwarding license, the relay communication module adds the Mac address of the first communication module to the forwarding list; After the relay communication module receives the cancel forwarding license sent by the first communication module, the relay communication module deletes the Mac address of the first communication module in the forwarding list.

9. A remote meter reading communication module, characterized in that: Based on the remote meter reading communication method according to any one of claims 1 to 8, the remote meter reading communication module comprises: a communication module, a radio frequency module and an interface circuit, wherein: The first end of the communication module is connected to the master station through the LTE network, the second end of the communication module is connected to the first end of the radio frequency module, and the third end of the communication module is connected to the first end of the interface circuit; the communication module is an OpenCPU communication module; The second end of the radio frequency module is communicatively connected to the second end of the radio frequency module in the other communication module; The second end of the interface circuit is connected to a measuring instrument; When the communication module of the current node is disconnected from the master station, the communication module of the current node is the first communication module, and the communication modules of other nodes are the second communication modules; the communication module of the first communication module is the first communication module, and the radio frequency module of the first communication module is the first radio frequency module; the communication module of the second communication module is the second communication module, and the radio frequency module of the second communication module is the second radio frequency module; The first communication module is connected to at least one of the second communication modules by means of the first radio frequency module and the second radio frequency module of the second communication module, the first communication module uses the remote meter reading communication method according to any one of claims 1 to 3 to find a relay communication module, and the relay communication module sends the measuring instrument data received by the first communication module to the master station; The second communication module responds to the first communication module using the remote meter reading communication method according to any one of claims 3 to 8.

10. The remote meter reading communication module according to claim 9, characterized in that: Also includes: Power module and indication circuit, wherein: The first end of the power module inputs a supply voltage, the second end of the power module is connected to the fourth end of the communication module, and the power module is used to convert the supply voltage to power the communication module and the indication circuit; The indication circuit is connected to the fifth end of the communication module and the fifth end of the power module, and the indication circuit is used to indicate the working status of the communication module.

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