Reliable data transmission method for mobile LoRa terminals

Abstract

The present invention discloses a reliable data transmission method for mobile LoRa terminals. First, the communication distance between the LoRa terminal and the gateway is determined through a single communication, and a parameter with the minimum transmission energy consumption is selected according to the communication distance. Then, to ensure transmission reliability, a terminal channel selection scheme is designed when the LoRa terminal is mobile. Finally, considering the mobility of the LoRa terminal, it is proposed to provide a reliable transmission service by using a mobile LoRa gateway, and a LoRa terminal position perception method is designed. Under the premise that the LoRa gateway is mobile, the LoRa gateway can follow the movement of the LoRa terminal, covering as many LoRa terminals as possible, so that as many LoRa terminals as possible can communicate at a faster communication rate and with lower transmission energy consumption. While ensuring reliable data transmission, the transmission energy consumption of the LoRa terminal is reduced as much as possible, thereby extending the life cycle of the LoRa network.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-power wide area networks in the Internet of Things, and mainly relates to a reliable data transmission method for mobile LoRa terminals. Background Art

[0002] Low-Power Wide-Area Networks (LPWAN) are a type of IoT technology (wireless communication technology) that can provide long-distance, low-power communication. Due to its small data, large connection, and low cost characteristics, LPWAN is widely used in large-scale scenarios such as smart industry, smart cities, and smart farms to provide low-power, long-distance communication. Based on whether the spectrum is licensed, the mainstream LPWAN technologies on the market can be divided into two categories: (1) Non-cellular technologies with unlicensed spectrum, mainly including LoRa (Long Range), Sigfox, etc. (2) Cellular IoT technologies with licensed spectrum, mainly including NB-IoT, LTE-M, etc. Among them, LoRa has the advantages of open architecture, on-demand autonomous networking, miniaturization and easy deployment. It is particularly suitable for outdoor environments that are not covered by operator networks, such as smart industry, smart cities, smart farms, and other environments that require long-term, low-power data monitoring. Therefore, it stands out among the LPWAN technologies. Therefore, conducting in-depth and forward-looking research on LoRa networks has important theoretical and application value.

[0003] A LoRa network primarily consists of terminals, gateways, network servers, and application servers. LoRa terminals and gateways are connected via LoRaWAN in a single-hop star network topology. Terminals transmit sensor data to the gateway using a pure ALOHA method according to specific transmission parameters. These transmission parameters primarily include carrier frequency (CF), spreading factor (SF), bandwidth (BW), code rate (CR), and transmit power (TP). A larger spreading factor (SF7-SF12) results in a lower transmission rate, a longer transmission distance, and increased energy consumption. A larger transmit power also results in a longer transmission distance and increased energy consumption. The combination of a carrier frequency and a spreading factor constitutes a channel between the terminal and the gateway. A LoRa gateway can set up to eight carrier frequencies, simultaneously monitoring and demodulating signals transmitted on these eight carrier frequencies. The communication process between LoRa terminals and gateways is subject to two types of transmission interference: co-SF interference and inter-SF interference. The gateway sends the demodulated data packets to the network server through a cellular network, Ethernet, or Wi-Fi network. After the network server parses and processes the data packets, it uploads the corresponding data to the application server according to the application requirements.

[0004] LoRa terminals, due to their advantages such as autonomous, on-demand networking, have been widely deployed in areas such as smart cities and smart agriculture. For example, in geo-location asset management, the LoRa network provides long-range communications and ultra-low-power geo-location asset management for transportation providers, healthcare, food services, and many other verticals. In wildlife tracking, users can track the movements of wildlife such as elephants and dolphins wearing LoRa terminals. In emergency rescue scenarios, the LoRa network, due to its strong interference resistance, is used for communication in situations such as earthquakes, forest fires, and volcanoes. Rescue workers entering disaster areas can communicate using their wearable LoRa terminals. In these scenarios, LoRa terminals are mobile, and the communication range with the LoRa gateway varies. Due to the complex transmission characteristics of LoRa and the limited parallel reception capability of the LoRa gateway, the mobility of LoRa terminals leads to uncertainties in transmission parameters, noise interference, and terminal distribution, which can easily result in data packets being unable to reach the LoRa gateway or failures due to numerous transmission collisions. Furthermore, due to the mobility of LoRa terminals, the LoRa gateway sometimes needs to move with the LoRa terminal to provide high-quality communication services (such as low power consumption and high data rates) to the mobile LoRa terminal over a long period of time. Therefore, when the LoRa terminal is mobile, how to allocate transmission parameters and schedule gateway downlink communication to ensure reliable transmission between the mobile LoRa terminal and the LoRa gateway, and to ensure low-power transmission as much as possible to extend the life cycle of the LoRa network is a core issue that needs to be solved urgently. Summary of the Invention

[0005] The present invention is aimed at the problem of communication unreliability caused by uncertainties such as communication distance, noise interference, and communication environment due to the mobility of LoRa terminals in the prior art. It provides a reliable data transmission method for mobile LoRa terminals. First, the communication distance between the LoRa terminal and the gateway is determined through a single communication, and the parameters with the lowest transmission energy consumption are selected according to the communication distance; then, to ensure transmission reliability, a terminal channel selection scheme is designed when the LoRa terminal is mobile; finally, considering the mobility of the LoRa terminal, it is proposed to use a mobile LoRa gateway to provide reliable transmission services, and a LoRa terminal position perception method is designed. Under the premise that the LoRa gateway is mobile, the LoRa gateway can follow the LoRa terminal to cover as many LoRa terminals as possible, so that as many LoRa terminals as possible can communicate at a faster communication rate and lower transmission energy consumption. While ensuring reliable data transmission, the transmission energy consumption of the LoRa terminal is reduced as much as possible, thereby extending the life cycle of the LoRa network.

[0006] In order to achieve the above object, the technical solution adopted in the present invention is: a reliable data transmission method for a mobile LoRa terminal, comprising the following steps:

[0007] S1, communication distance determination: determine the communication distance between the LoRa terminal and the LoRa gateway, and determine the spreading factor SF and transmission power TP required for the LoRa terminal transmission based on the communication distance;

[0008] S2, LoRa terminal transmission channel selection: The LoRa terminal initially randomly selects a channel to send an uplink data packet. If the uplink is successful, the LoRa gateway will send the corresponding downlink information to the terminal, prompting the LoRa terminal to succeed in uplinking and updating the geographical location of the LoRa gateway. As the number of communications increases, the LoRa terminal's channel randomly selects an uplink transmission channel with a probability of p, and selects the channel with the highest success probability from the historical channels with successful transmission with a probability of (1-p). The LoRa terminal records the transmission success rate when using a given uplink channel for transmission;

[0009] S3, LoRa terminal movement perception: The mobile LoRa gateway perceives the density of terminals based on the received terminal signal strength RSSI and GPS information, and moves to a place with a high degree of terminal concentration for communication.

[0010] As an improvement of the present invention, step S1 specifically includes:

[0011] S11: The LoRa terminal sends an uplink data packet to the mobile LoRa gateway with the maximum transmission parameters for the first time;

[0012] S12: After receiving the uplink data packet of the LoRa terminal, the mobile LoRa gateway sends a first downlink data packet with the uplink transmission parameters of the terminal to notify the LoRa terminal that the uplink is successful, and adds its own GPS data at that time to the first downlink data packet;

[0013] S13: After the LoRa terminal receives the GPS data contained in the downlink data packet of the mobile LoRa gateway, before each uplink, it calculates the communication distance between the two based on its own GPS and the GPS data of the mobile LoRa gateway;

[0014] S14: The LoRa terminal calculates a transmission parameter combination that meets the communication distance requirement based on the communication distance and path loss model, and selects the one with the lowest transmission energy consumption, wherein the combination includes the spreading factor SF and the transmission power TP;

[0015] S15: If the location of the mobile LoRa gateway changes, when receiving the LoRa terminal uplink data packet after the location change, it updates its own GPS information in the downlink data packet sent for the first time after the location change.

[0016] As an improvement of the present invention, the uplink channel success rate in step S2 is recorded as follows: if the LoRa terminal sends a total of m uplink data packets through channel x, of which n downlink data packets are received, the downlink success rate of channel x is n / m, and the LoRa terminal needs to store locally: x, n, m; for each successful uplink through channel x, n and m are each +1; if the uplink is unsuccessful, the m value is +1, and the n value remains unchanged.

[0017] As an improvement of the present invention, in step S2, the channel selection scheme for each time the LoRa terminal sends an uplink data packet is as follows: randomly select a real number between 0 and 1. If the number is in the interval [0, p), the LoRa terminal randomly selects a channel to send the uplink data; if the number is in the interval [p, 1], the LoRa terminal randomly selects the channel with the largest current success rate (n / m) to send the uplink data packet.

[0018] As another improvement of the present invention, in step S3, after receiving the uplink data packet sent by the mobile LoRa terminal, the mobile LoRa gateway can parse the RSSI value of the uplink data packet and the GPS value when the LoRa terminal sends the data.

[0019] If it is a single mobile LoRa gateway, the mobile LoRa gateway locally aggregates the GPS information of all mobile LoRa terminals currently received, calibrates the error based on the point with the strongest RSSI value, calculates the terminal gathering center at fixed intervals or sets a terminal movement distance threshold to determine the point with the densest mobile LoRa terminals;

[0020] If there are multiple mobile LoRa gateways, calculate the terminal gathering center at fixed intervals or set a terminal movement distance threshold to determine the points where mobile LoRa terminals are more dense.

[0021] As another improvement of the present invention, in step S3, if there is a single mobile LoRa gateway, when a large number of terminals are found to be moving on a large scale, a clustering method is used to determine the points where the mobile LoRa terminals are densely packed; if there are multiple mobile LoRa gateways, when a large number of terminals are found to be moving on a large scale, the mobile LoRa gateway immediately forwards the information to the network server after receiving the GPS and RSSI value information of the mobile LoRa terminal. The network server globally calculates the points where the top k terminals are most densely distributed, where k is the number of mobile LoRa gateways, and sends scheduling information to each mobile LoRa gateway to schedule each mobile LoRa gateway to go to the nearest point.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) This paper proposes a reliable data transmission method for mobile LoRa terminals for the first time. In various applications such as smart cities, smart farms, and geographic asset tracking, LoRa terminals are often mobile, which leads to uncertainties in transmission parameters, noise interference, and communication environment, ultimately resulting in low data transmission reliability. To address this issue, this paper proposes a reliable data transmission method for LoRa terminals in mobile scenarios.

[0024] (2) LoRa's complex transmission characteristics, such as the coupling of transmission parameters and communication distance, the existence of Co-SF interference and Inter-SF interference, and the limited parallel downlink capability of the LoRa gateway, lead to a large number of transmission conflicts. In a mobile environment, the communication uncertainty caused by the change of the LoRa terminal position further exacerbates the occurrence of such problems. The present invention can ensure the reliability of data transmission when the LoRa terminal is mobile by sensing the communication distance and transmission conflicts.

[0025] (3) Considering that in some applications, the range of movement of LoRa terminals is relatively wide, the present invention proposes to use a mobile LoRa gateway to sense and follow the movement of LoRa terminals to provide long-term and reliable transmission services for mobile LoRa terminals. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a system architecture diagram of the reliable data transmission method for mobile LoRa terminals of the present invention;

[0027] Figure 2 This is a working diagram of a reliable data transmission method terminal for a mobile LoRa terminal of the present invention;

[0028] Figure 3 The figure is a workflow diagram of the gateway of the reliable data transmission method for mobile LoRa terminals of the present invention. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0030] Example 1

[0031] A reliable data transmission method for mobile LoRa terminals, the specific architecture of which is as follows Figure 1 As shown, it is composed of a mobile LoRa terminal, a (mobile) LoRa gateway, and a network server. The mobile LoRa terminal sends data to the (mobile) LoRa gateway, and the (mobile) LoRa gateway forwards the received data to the network server. The reliable data transmission method for mobile LoRa terminals of the present invention specifically includes the following steps:

[0032] Step S1: First, determine the communication distance between the LoRa terminal and the LoRa gateway, and then determine the spreading factor (SF) and transmission power (TP) required for the LoRa terminal transmission based on the communication distance. When the LoRa gateway successfully downlinks for the first time at the current location, it sends its own GPS information to the LoRa terminal. Based on its own GPS information, LoRa can calculate the communication distance with the gateway based on the GPS information of both before each transmission, and select the spreading factor and transmission power that can meet the communication requirements and consume the least transmission energy according to the communication distance;

[0033] Step S11: The LoRa terminal sends an uplink data packet to the (mobile) LoRa gateway with the maximum transmission parameter for the first time to ensure that the (mobile) LoRa gateway receives the uplink data packet as much as possible;

[0034] Step S12: After receiving the uplink data packet of the LoRa terminal, the mobile LoRa gateway sends a first downlink data packet with the uplink transmission parameters of the terminal to notify the LoRa terminal that the uplink is successful, and adds its own GPS data at that time to the first downlink data packet;

[0035] Step S13: After the LoRa terminal receives the GPS data contained in the downlink data packet of the mobile LoRa gateway, before each uplink, it calculates the communication distance between the two based on its own GPS (the LoRa terminal may be equipped with a GPS module) and the GPS data of the mobile LoRa gateway;

[0036] Step S14: The LoRa terminal can calculate several transmission parameter combinations (mainly including SF and TP) that meet the communication distance requirements based on the communication distance and path loss model, and select the combination with the lowest transmission energy consumption. In applications with high tolerance for transmission energy consumption, if a large number of terminals choose the same spreading factor, a larger spreading factor that meets the communication distance can be selected step by step. For example, the combination of SF7 and TP12, and the combination of SF8 and TP10 can both meet the requirement of a communication distance of 100 meters, but the former has lower transmission energy consumption, and the LoRa terminal prefers the former as the transmission parameter. If a large number of terminals choose SF7, some terminals may choose a combination of SF8 and TP10;

[0037] Step S15: If the mobile LoRa gateway changes its position, it needs to update its own GPS information in the downlink data packet sent for the first time after the position change when receiving the LoRa terminal uplink data packet after the position change.

[0038] Step S2: The LoRa terminal initially randomly selects a channel to send an uplink data packet. If the uplink is successful, the LoRa gateway will send a corresponding downlink message to the terminal, prompting the LoRa terminal that the uplink is successful and updating the geographical location of the LoRa gateway to ensure the reliability of communication. As the number of communications increases, the channel selection of the LoRa terminal can adopt a random probability mechanism, that is, the uplink transmission channel is randomly selected with a probability of p, and the channel with the highest success probability is selected from the historical channels with successful transmission with a probability of (1-p). The probability can be adjusted according to user needs or actual communication conditions;

[0039] Initially, the LoRa terminal randomly selects a channel to send uplink data. If it can successfully receive the downlink data packet sent by the mobile LoRa gateway, it means that the corresponding uplink data packet is sent successfully, that is, the corresponding uplink channel can successfully send data. The LoRa terminal records the transmission success rate when using the given uplink channel for transmission;

[0040] The uplink channel success rate is recorded as follows: If the LoRa terminal sends m uplink data packets through channel x and receives n downlink data packets, the downlink success rate of channel x is n / m. The LoRa terminal needs to store x, n, and m locally. After that, each time the uplink is successful through channel x, n and m are increased by 1. If the uplink is unsuccessful, m is increased by 1 and n remains unchanged.

[0041] Each time a LoRa terminal transmits an uplink data packet, it selects a channel as follows: a random number between 0 and 1 is selected. If the number is within the interval [0, p), the LoRa terminal randomly selects a channel to transmit the uplink data. If the number is within the interval [p, 1], the LoRa terminal randomly selects the channel with the highest success rate (n / m) to transmit the uplink data packet. The proportion of random selection can be adjusted based on user needs and actual conditions. For example, in highly dynamic environments with significant fluctuations in channel quality, the proportion of random selection can be appropriately increased. This scheme can adapt to factors such as noise interference, channel quality fluctuations, and communication distance changes when the LoRa terminal is mobile. Random channel selection avoids the invariant selection of a single or limited number of channels, allowing channel selection to adapt to dynamic environmental changes and preventing the LoRa terminal from falling into an infinite loop in channel selection, thus ensuring transmission reliability. Selecting a channel with a high success rate provides the basis for successful uplink transmission. The ratio of the two can be adjusted based on actual conditions. For example, in highly dynamic environments, frequent terminal movement, and generally low channel success rates, the proportion of random channel selection can be appropriately increased to quickly select a successful uplink channel.

[0042] Therefore, the working process of the reliable data transmission method terminal for mobile LoRa terminal of the present invention is as follows Figure 2As shown, a mobile LoRa terminal initially sends an uplink data packet to the gateway using the maximum TP, SF, and a random channel. If it does not receive a downlink data packet from the gateway, it continuously changes to a random channel for transmission. If it receives a downlink data packet from the gateway, it calculates the communication distance based on the gateway's GPS information contained in the downlink data packet. The terminal selects the transmission parameters required for the next transmission based on the communication distance and randomly selects a channel to send the uplink data packet. If a downlink data packet is received, the downlink count n and uplink count m are both increased by 1, and the downlink success rate of the channel becomes (n+1) / (m+1). If no downlink data packet is received, the downlink count n remains unchanged, the uplink count m+1, and the downlink success rate of the channel becomes n / (m+1). The uplink transmission channel is randomly selected with probability p, and the channel with the highest success probability is selected from the historical channels with successful transmissions with probability (1-p).

[0043] Step S3: Since LoRa terminals are constantly moving, their geographic location and clustering will constantly change. Therefore, a LoRa gateway can be combined with a mobile carrier such as a drone to form a mobile LoRa gateway. The mobile LoRa gateway detects the density of terminals based on the received terminal signal strength (RSSI) and GPS information, and moves to an area with high terminal clustering, enabling as many terminals as possible to communicate with the lowest possible transmission energy consumption and the fastest possible transmission rate. In this step, the use of a mobile LoRa gateway is proposed to adapt to the mobility of LoRa terminals for the following reasons: Due to the mobility of LoRa terminals, the geographic location and clustering of terminals will constantly change. To provide better communication, such as lower transmission energy consumption and faster transmission rates, for as many terminals as possible, it is proposed to use a mobile LoRa gateway to provide communication services for mobile LoRa terminals. The mobile LoRa gateway can follow the movement of LoRa terminals based on the movement trend and density of LoRa terminals, thereby ensuring that high-quality communication services are always provided to LoRa terminals.

[0044] Each time a mobile LoRa terminal communicates with a mobile LoRa gateway for the first time after a change in location, it includes its GPS information in the uplink data packet. Upon receiving the uplink data packet from the mobile LoRa terminal, the mobile LoRa gateway can parse the RSSI value of the uplink data packet and determine the GPS location of the LoRa terminal at the time the data was sent.

[0045] If it is a single mobile LoRa gateway, the mobile LoRa gateway can locally summarize the GPS information of all mobile LoRa terminals currently received, and calibrate the error based on the strongest RSSI value. It can calculate the terminal aggregation center at regular intervals, or set a terminal movement distance threshold. If a large number of terminals are found to be moving on a large scale, such as changes in the aggregation situation, a clustering method can be used to determine the points where mobile LoRa terminals are more densely populated. This can be determined based on the degree of overlap in the terminal communication range, or the total distance to all terminals and the shortest requirement.

[0046] If there are multiple mobile LoRa gateways, the terminal gathering center can also be calculated at regular intervals, or a terminal movement distance threshold can be set. If a large number of terminals are found to be moving on a large scale, such as a change in the gathering situation, the mobile LoRa gateway needs to immediately forward the information to the network server after receiving information such as the GPS and RSSI values ​​of the mobile LoRa terminal. The network server globally calculates the top k points with the densest terminal distribution, where k is the number of mobile LoRa gateways, and sends scheduling information to each mobile LoRa gateway, scheduling each mobile LoRa gateway to go to the nearest point, so as to provide low-power, high-speed transmission for the mobile LoRa terminal while saving mobile carrier energy consumption as much as possible.

[0047] Therefore, the workflow of the reliable data transmission method gateway for mobile LoRa terminals of the present invention is as follows: Figure 3 As shown in the figure. After receiving the uplink data packet from the mobile LoRa terminal, the gateway sends a downlink data packet to the terminal. If this is the first communication or the first communication after the mobile LoRa gateway's location has changed, the downlink data packet must include the gateway's own GPS. If the terminal's location changes, the gateway will receive an uplink data packet containing the terminal's GPS information. In a single mobile LoRa gateway scenario, the single mobile LoRa gateway will calculate the mobile location based on this information and move within the communication range of the LoRa terminal. In a multi-mobile LoRa gateway scenario, the gateway that receives the uplink data packet will forward the uplink data packet to the network server, which will schedule multiple gateways to transmit the downlink data packet. The mobile LoRa gateway will move to the terminal signal aggregation point to provide transmission services.

[0048] This invention addresses the issue of communication unreliability caused by uncertainties in communication distance, noise interference, and the communication environment when LoRa terminals are mobile. This method logically comprises three main steps: determining the communication distance, selecting a LoRa terminal transmission channel, and sensing LoRa terminal mobility. First, the invention determines the communication distance between the LoRa terminal and the gateway through a single communication session and selects parameters that minimize transmission energy consumption based on the communication distance. Secondly, to ensure transmission reliability, a terminal channel selection scheme is designed for mobile LoRa terminals. Finally, considering the mobility of LoRa terminals, a reliable transmission service is proposed using a mobile LoRa gateway. A LoRa terminal location sensing scheme is designed. Given the mobility of the LoRa gateway, the gateway can follow the movement of the LoRa terminal, locating it close to as many LoRa terminals as possible. This allows as many LoRa terminals as possible to communicate at a faster rate and with less transmission energy. This ensures reliable data transmission while minimizing LoRa terminal transmission energy consumption, extending the LoRa network lifecycle.

[0049] It should be noted that the above content merely illustrates the technical idea of ​​the present invention and cannot be used to limit the scope of protection of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications all fall within the scope of protection of the claims of the present invention.

Claims

1. A reliable data transmission method for mobile LoRa terminals, characterized in that: The process includes the following steps: S1, communication distance determination: determine the communication distance between the LoRa terminal and the LoRa gateway, and determine the spreading factor SF and transmission power TP required for the LoRa terminal transmission based on the communication distance; S2, LoRa terminal transmission channel selection: The LoRa terminal randomly selects a channel to send an uplink data packet at the beginning. If the uplink is successful, the LoRa gateway will send the corresponding downlink information to the terminal, prompting the LoRa terminal that the uplink is successful and updating the geographical location of the LoRa gateway. As the number of communications increases, the LoRa terminal's channel randomly selects an uplink transmission channel with a probability of p, and selects the channel with the highest success probability from the historical channels with successful transmission with a probability of (1-p). The LoRa terminal records the transmission success rate when using a given uplink channel for transmission; the uplink channel success rate is recorded as follows: if the LoRa terminal sends a total of m uplink data packets through channel x, of which n downlink data packets are received, then the downlink success rate of channel x is n / m, and the LoRa terminal needs to store locally: x, n, m; each time the uplink is successful through channel x, n and m are each +1; if the uplink is unsuccessful, the m value is +1, and the n value remains unchanged; The channel selection scheme for each uplink data packet sent by the LoRa terminal is as follows: a real number between 0 and 1 is randomly selected. If the real number is within the interval [0, p), the LoRa terminal randomly selects a channel to send the uplink data; if the real number is within the interval [p, 1], the LoRa terminal randomly selects the channel with the highest current success rate (n / m) to send the uplink data packet; S3, LoRa terminal movement perception: The mobile LoRa gateway perceives the density of terminals based on the received terminal signal strength RSSI and GPS information, and moves to a place with a high degree of terminal concentration for communication.

2. The reliable data transmission method for a mobile LoRa terminal as claimed in claim 1, wherein: The step S1 specifically includes: S11: The LoRa terminal sends an uplink data packet to the mobile LoRa gateway with the maximum transmission parameters for the first time; S12: After receiving the uplink data packet of the LoRa terminal, the mobile LoRa gateway sends a first downlink data packet with the uplink transmission parameters of the terminal to notify the LoRa terminal that the uplink is successful, and adds its own GPS data at that time to the first downlink data packet; S13: After the LoRa terminal receives the GPS data contained in the downlink data packet of the mobile LoRa gateway, before each uplink, it calculates the communication distance between the two based on its own GPS and the GPS data of the mobile LoRa gateway; S14: The LoRa terminal calculates a transmission parameter combination that meets the communication distance requirement based on the communication distance and path loss model, and selects the one with the lowest transmission energy consumption, wherein the combination includes the spreading factor SF and the transmission power TP; S15: If the location of the mobile LoRa gateway changes, when receiving the LoRa terminal uplink data packet after the location change, it updates its own GPS information in the downlink data packet sent for the first time after the location change.

3. The reliable data transmission method for a mobile LoRa terminal as claimed in claim 2, wherein: In step S3, after receiving the uplink data packet sent by the mobile LoRa terminal, the mobile LoRa gateway can parse the RSSI value of the uplink data packet and the GPS value when the LoRa terminal sends the data. If it is a single mobile LoRa gateway, the mobile LoRa gateway locally aggregates the GPS information of all mobile LoRa terminals currently received, calibrates the error based on the point with the strongest RSSI value, calculates the terminal gathering center at fixed intervals or sets a terminal movement distance threshold to determine the point with the densest mobile LoRa terminals; If there are multiple mobile LoRa gateways, calculate the terminal gathering center at fixed intervals or set a terminal movement distance threshold to determine the points where mobile LoRa terminals are more dense.

4. The reliable data transmission method for a mobile LoRa terminal as claimed in claim 3, wherein: In step S3, if there is a single mobile LoRa gateway, when a large number of terminals are found to be moving on a large scale, a clustering method is used to determine the points where the mobile LoRa terminals are densely packed. If there are multiple mobile LoRa gateways, when a large number of terminals are found to be moving on a large scale, the mobile LoRa gateway immediately forwards the information to the network server after receiving the GPS and RSSI value information of the mobile LoRa terminals. The network server globally calculates the top k points with the densest terminal distribution, where k is the number of mobile LoRa gateways, and sends scheduling information to each mobile LoRa gateway, scheduling each mobile LoRa gateway to go to the nearest point.

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