CN116567788A - Low-power-consumption data transmission method for LoRa (virtual local area network) terminal based on multi-mobile LoRa gateway - Google Patents

Low-power-consumption data transmission method for LoRa (virtual local area network) terminal based on multi-mobile LoRa gateway Download PDF

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Publication number
CN116567788A
CN116567788A CN202310656751.8A CN202310656751A CN116567788A CN 116567788 A CN116567788 A CN 116567788A CN 202310656751 A CN202310656751 A CN 202310656751A CN 116567788 A CN116567788 A CN 116567788A
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lora
terminal
mobile
gateway
lora terminal
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罗军舟
陈慈媛
熊润群
徐祝庆
林敬凯
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Southeast University
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Southeast University
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/02—Power saving arrangements
    • H04W52/0209—Power saving arrangements in terminal devices
    • H04W52/0212—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave
    • H04W52/0216—Power saving arrangements in terminal devices managed by the network, e.g. network or access point is master and terminal is slave using a pre-established activity schedule, e.g. traffic indication frame
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/06—TPC algorithms
    • H04W52/14—Separate analysis of uplink or downlink
    • H04W52/146—Uplink power control
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/28—TPC being performed according to specific parameters using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
    • H04W52/283—Power depending on the position of the mobile
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W52/00—Power management, e.g. TPC [Transmission Power Control], power saving or power classes
    • H04W52/04—TPC
    • H04W52/18—TPC being performed according to specific parameters
    • H04W52/28—TPC being performed according to specific parameters using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission
    • H04W52/288—TPC being performed according to specific parameters using user profile, e.g. mobile speed, priority or network state, e.g. standby, idle or non transmission taking into account the usage mode, e.g. hands-free, data transmission, telephone
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/16—Gateway arrangements
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02D—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE
    • Y02D30/00—Reducing energy consumption in communication networks
    • Y02D30/70—Reducing energy consumption in communication networks in wireless communication networks

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

The invention discloses a low-power-consumption data transmission method of a LoRa terminal based on a plurality of mobile LoRa gateways, which comprises the steps of determining a moving track of each mobile LoRa gateway and a terminal range responsible for service according to deployment conditions of the LoRa terminal, and setting a position of the mobile LoRa gateway at a designated moment and a corresponding LoRa terminal batch needing to perform data transmission; starting a channel activity detection mode, wherein the LoRa terminal perceives the arrival of the mobile LoRa gateway with low power consumption, is in a dormant mode when communication is not needed, and performs data transmission after confirming the arrival of the mobile LoRa gateway; after entering a communication range of the LoRa terminal, the multi-mobile LoRa gateway performs data collection with the LoRa terminal, and after receiving an instruction of the mobile LoRa gateway, the LoRa terminal performs data transmission with the mobile gateway according to transmission parameters indicated by the mobile LoRa gateway; and finally, aiming at the online application, the LoRa terminal sends the uplink request data packet to the network server through the mobile LoRa gateway, and the network server synthesizes the uplink data packet of the LoRa terminal to complete real-time scheduling.

Description

Low-power-consumption data transmission method for LoRa (virtual local area network) terminal based on multi-mobile LoRa gateway
Technical Field
The invention belongs to the technical field of low-power-consumption wide area networks in the Internet of things, and mainly relates to a low-power-consumption data transmission method of a LoRa terminal based on a multi-mobile LoRa gateway.
Background
With the rapid development of the internet of things technology (especially wireless communication technology), people are moving into the era of everything interconnection. Wireless communication technologies can be mainly classified into two types according to different communication distances: (1) The near field wireless communication technology mainly comprises Wi-Fi, bluetooth, RFID and the like; (2) Long-distance wireless communication technology mainly comprises GSM, 5G, etc. Where the former cannot cover wide area scenarios, conventional long-range wireless communication techniques often trade off significant terminal power consumption for communication coverage. Therefore, there is an increasing need for Wide-coverage, low-Power, low-cost wireless communications, in which context Low-Power Wide-Area Networks (LPWANs) technology has evolved. The currently prevailing LPWAN technologies on the market can be divided into two categories depending on whether spectrum is licensed or not: (1) Unlicensed spectrum technologies mainly comprise LoRa (Long Range), sigfox and the like; (2) Techniques for licensed spectrum include mainly NB-IoT, LTE-M, etc. The LoRa has the advantages of open architecture, on-demand autonomous networking, miniaturization, easy deployment and the like, and attracts wide attention in academia and industry. Therefore, extensive and thorough prospective research around the LoRa network has important theoretical and application value.
LoRa terminals have been widely deployed in smart cities, smart agriculture, and other fields because of their advantages of being capable of autonomous on-demand networking. The LoRa network mainly comprises a terminal, a gateway, a network server, an application server and the like. The LoRa terminal is often powered by a battery and communicates with the gateway through a certain transmission parameter, the gateway forwards the demodulated data packet to the network server through a network such as an ethernet, and the network server uploads corresponding data to the application server according to application requirements. LoRa terminal is often applied to fields such as wisdom city, field monitoring, wisdom agriculture and is used for collecting data, and this kind of scene often has that the building shelters from characteristics such as many, the environment is abominable, network coverage is few, leads to there to be problem such as communication distance far away, communication interference is big between terminal and the gateway. Taking livestock management as an example, the LoRa terminal needs to forward the animal position to the pasture owner, but because the pasture position is far away and the range is wide, the signal attenuation is large, and the remote terminal often needs to select a transmission parameter party with larger energy consumption to communicate with the gateway. Therefore, in a complex wide area environment in a deep building or a remote area, the actual cruising ability of the LoRa terminal battery is usually only 1-2 years, which is far lower than expected, and the problems of unfair energy consumption among terminals and the like exist. The main reason is that in a complex wide area environment, more LoRa terminals are far away from the gateway, and more energy-consuming transmission parameters are needed to be selected for data transmission. On the other hand, in a complex environment with dense deployment or serious environmental interference, serious transmission conflict can be generated when the loRa terminal transmits data, so that the data delivery rate is low, and the transmission power consumption of the terminal is increased. As the LoRa terminals are mostly battery powered, the battery capacity is limited, and in many communication sensing applications, the communication overhead is the main factor of battery consumption. Therefore, in a complex wide area environment, the transmission power consumption of the LoRa terminal is reduced, so that the battery endurance of the LoRa terminal is improved, and the life cycle of the LoRa network is prolonged.
Disclosure of Invention
Aiming at the problems of low battery endurance capacity, unfair energy consumption among terminals and short life cycle of a LoRa network in the prior art, the invention provides a low-power-consumption data transmission method of a LoRa terminal based on a plurality of mobile LoRa gateways, which is characterized in that the mobile track of each mobile LoRa gateway and the terminal range responsible for providing transmission service are determined according to the deployment condition of the LoRa terminal, and the position of the mobile LoRa gateway at the appointed moment and the corresponding LoRa terminal batch needing data transmission are set; starting a channel activity detection mode, wherein the LoRa terminal perceives the arrival of the mobile LoRa gateway with low power consumption, and the LoRa terminal is in a dormant mode when communication is not needed, and performs data transmission after confirming the arrival of the mobile LoRa gateway; after entering a communication range of the LoRa terminal, the multi-mobile LoRa gateway performs data collection with the LoRa terminal, and after receiving an instruction of the mobile LoRa gateway, the LoRa terminal performs data transmission with the mobile gateway according to transmission parameters indicated by the mobile LoRa gateway; and finally, aiming at the online application, the LoRa terminal sends the uplink request data packet to the network server through the mobile LoRa gateway, and the network server synthesizes the uplink data packet of the LoRa terminal to complete real-time scheduling. The method of the invention can lead the mobile gateway to freely and flexibly approach the terminal, greatly shorten the communication distance, lead the terminal to realize data communication with lower transmitting power and faster transmitting speed, greatly reduce the transmission power consumption of the terminal and further prolong the life cycle of the whole LoRa network.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: a low-power consumption data transmission method of a LoRa terminal based on a multi-mobile LoRa gateway comprises the following steps:
s1: determining the moving track of each moving LoRa gateway and the terminal range responsible for providing transmission service according to the deployment condition of the LoRa terminals, and setting the position of the moving LoRa gateway at the appointed moment and the corresponding LoRa terminal batch needing to perform data transmission;
s2: starting a channel activity detection mode, wherein the LoRa terminal perceives the arrival of the mobile LoRa gateway with low power consumption, and the LoRa terminal is in a dormant mode when communication is not needed, and performs data transmission after confirming the arrival of the mobile LoRa gateway;
s3: after entering a communication range of the LoRa terminal, the multi-mobile LoRa gateway performs data collection with the LoRa terminal, and after receiving an instruction of the mobile LoRa gateway, the LoRa terminal performs data transmission with the mobile gateway according to transmission parameters indicated by the mobile LoRa gateway;
s4: for online application, the LoRa terminal sends the uplink request data packet to the network server through the mobile LoRa gateway, and the network server synthesizes the uplink data packet of the LoRa terminal to complete real-time scheduling.
As an improvement of the present invention, the step S1 specifically includes:
s11: modeling the LoRa terminal deployment scenario as a graph g= (V, E), where V represents the set of all LoRa terminals, E represents the set of edges between terminals, edges between terminals (V i ,v j ) On which there is a non-negative weight d ij Determining a set of edges that can connect all the LoRa terminals into a closed loop, and making the sum of the edges of the set as small as possible;
s12: randomly selecting a terminal i as a starting point of a moving track, and selecting a weight d from edges connected with the starting point ij The smallest side is used as a first section of moving track, the terminal j is used as a second moving point, and a closed loop L formed by all terminals can be obtained by analogy, and the sum of the side weights is smaller;
s13: calculating the length L of a closed loop L, wherein the length of a moving track of each moving LoRa gateway is L/k+/-s, s is the length of the track at the position where the track just ends and the terminal, and k is the number of the moving LoRa gateways; and (5) completing track planning and communication area division.
As an improvement of the present invention, step S2 specifically includes:
s21: in the off-line application, the communication time between the LoRa terminal and the mobile gateway is preset, and the LoRa terminal wakes up in advance before a communication point to enter a channel activity detection mode to monitor the arrival of the mobile gateway;
s22: when the mobile LoRa gateway is monitored to be reached, the LoRa terminal enters a receiving RX mode to receive a downlink data packet sent by the mobile LoRa gateway, wherein the downlink data packet for the LoRa terminal comprises transmission parameters which should be used for sending an uplink data packet by the LoRa terminal.
As another improvement of the present invention, in the step S22, the mobile LoRa gateway performs time alignment with the LoRa terminal every time it communicates.
As another improvement of the present invention, the step S3 specifically includes:
s31: after entering a communication range of the LoRa terminal, the mobile gateway communicates with the LoRa terminal, wherein the spreading factor SF of each LoRa terminal is fixed and the spreading factor SF is the same in the transmission parameters of the communication, and the transmission power TP of each LoRa terminal is fixed;
s32, the mobile gateway transmits a downlink data packet containing channel configuration information to the corresponding LoRa terminal; the channel configuration information at least comprises transmission parameter setting, transmission time calibration and a LoRa terminal Dev ID;
s33: the LoRa terminal monitors the LoRa signal sent by the mobile gateway in the CAD mode with low power consumption, if the related signal sent by the mobile gateway is monitored, the mobile gateway is indicated to reach the communication range of the terminal, the data of the terminal are to be collected, and the terminal is converted from the CAD mode to the RX mode;
s34, after the LoRa terminal receives the downlink data packet sent by the mobile gateway in the RX mode, if the downlink data packet contains information aiming at the LoRa terminal, the LoRa terminal can transmit data in the communication, and the terminal enters a transmission TX mode to start uploading data; if the downlink data packet does not indicate the terminal, the terminal reenters an RX mode until receiving the downlink indication data packet for the terminal;
s35: and after finishing data transmission, the LoRa terminal SLEEPs, enters a SLEEP mode from a TX mode, starts a low-power consumption sensing mobile LoRa gateway from the SLEEP mode to a CAD mode when the communication of the next period starts, and the mobile gateway performs data collection of the next LoRa terminal and moves according to a track planned in advance until the mobile gateway enters the communication range of the next LoRa terminal needing communication.
As a further improvement of the present invention, in the transmission parameters of step S31, in the case that the spreading factor SF and the transmission power TP are fixed, for the dense distribution of terminals using the same spreading factor SF, the same batch of 8 ra terminals is adopted for data transmission, the random allocation manner is adopted for the channels CF of the 8 terminals, the second batch of ra terminal communication is performed after the first batch is finished, and the communication of the remaining ra terminals is performed by analogy.
As a further improvement of the present invention, the step S4 specifically includes:
s41: the LoRa terminal sends short prompt information by using the maximum transmission parameters (TP, SF) to inform the mobile LoRa gateway in the maximum communication range that the data collection requirement exists, and then enters a channel activity detection mode; the short prompt message at least comprises a device ID (DevID) of the LoRa terminal, geographic position information (GPS) and the length of a data packet to be uplink;
s42: after receiving the short prompt data packet of the LoRa terminal in the communication range, the mobile LoRa gateway forwards the data packet to the network server, and the network server acquires information of the LoRa terminal needing to be communicated according to the short prompt data packet sent by the LoRa terminal, stops at the current communication position or the appointed charging station according to the application requirement after completing data transmission, and waits for the next scheduling instruction of the network server.
As a further improvement of the present invention, in step S42, the mobile gateway with the largest R value is scheduled to be close to the LoRa terminal according to the following formula, where r=k·1/d+ (1-k) ·e, D is the communication distance between the mobile gateway and the LoRa terminal, E is the remaining power of the mobile gateway, and k is the weight of the communication distance and the power of the mobile gateway set by the user according to the application requirement.
Compared with the prior art, the invention has the beneficial effects that:
(1) The mobile LoRa gateway is utilized to carry out low-power transmission of the LoRa terminal for the first time, compared with the existing fixed gateway mode, the mobile LoRa gateway can fundamentally solve the problem that a remote terminal needs to select transmission parameters with more energy consumption, so that the transmission power consumption is reduced, the energy consumption between terminals is avoided, the life cycle of the LoRa network is prolonged, the method meets the large trend of the collection of the environment-friendly energy-saving network in the industry, and the deployment requirement under multiple scenes can be met.
(2) The key performance indexes of the wireless sensor network are wide coverage, low cost and low power consumption, and the invention aims at a large number of transmission conflicts and the increase of transmission power consumption caused by the complex transmission characteristics of the LoRa and the limited parallel receiving capacity of the LoRa gateway, reduces the transmission power consumption of the LoRa terminal, ensures the reliability and concurrency of the data transmission of the LoRa terminal, and can meet the transmission characteristics of small data and large connection of the LoRa network.
(3) In order to further cope with the increasing application scale and the increasing demands, the invention designs corresponding transmission mechanisms for offline application and online application respectively so as to increase the universality of the method, and can be applied to the fields of smart cities, smart factories, smart farms and the like.
Drawings
FIG. 1 is a system architecture diagram of a low power consumption data transmission method of a LoRa terminal based on a multi-mobile LoRa gateway of the present invention;
FIG. 2 is a flow chart of the operation of the LoRa terminal in the low power consumption data transmission method of the LoRa terminal based on the multi-mobile LoRa gateway of the present invention;
fig. 3 is a flowchart of the operation of the LoRa gateway in the low power consumption data transmission method of the LoRa terminal based on the multi-mobile LoRa gateway.
Detailed Description
The present invention is further illustrated in the following drawings and detailed description, which are to be understood as being merely illustrative of the invention and not limiting the scope of the invention.
Example 1
A terminal low-power consumption data transmission method based on multiple mobile gateways is shown in figure 1, wherein a ground station comprises an unmanned aerial vehicle ground station and a LoRa network server, and the ground station controls the flight of the unmanned aerial vehicle and the data transmission of the LoRa gateway through an Ethernet; the unmanned aerial vehicle comprises a flight control board, a battery and other parts, and carries the LoRa gateway to form a mobile LoRa gateway; and the mobile LoRa performs data transmission with the LoRa terminal on the ground according to an offline scheduling scheme planned in advance by the gateway. The method comprises the following steps:
step S1: and determining the respective movement track of the multi-movement LoRa gateway and the responsible communication area, namely determining the terminal needing to provide the data transmission service. In the off-line application, according to the deployment condition of the LoRa terminals, determining the moving track of each mobile LoRa gateway and the terminal range responsible for providing transmission service, and setting the position of the mobile LoRa gateway at the appointed moment and the corresponding LoRa terminal batch needing data transmission;
before step S1, a plurality of mobile LoRa gateways are set up, the mobile carrier (such as unmanned aerial vehicle) is utilized to carry the LoRa gateway and close to the LoRa terminal for data collection, the gateway can be close to the terminal for data collection, the LoRa terminal can perform low-power-consumption data transmission, and the specific process is as follows:
the LoRa gateway is carried on a mobile carrier, and the mobile carrier can be an unmanned aerial vehicle, an unmanned ship and other tools capable of carrying the LoRa gateway for moving; the LoRa gateway is provided with a module capable of communicating with the LoRa terminal offline, and can also communicate with the LoRa network server in online application and communicate under the real-time instruction of the network server. The mobile carrier is provided with a mobile module which can move according to a preset track, and can also communicate with the ground station in real time in online application and move under the real-time instruction of the ground station.
The specific method of the step S1 is as follows:
in the off-line application, the service area division is performed on the multiple mobile LoRa gateways, that is, the moving range of each mobile LoRa gateway and the LoRa terminal that needs to be responsible for data transmission by the mobile gateway are determined. Assuming that k mobile LoRa gateways are provided, the mobile LoRa gateways will start from respective starting points and move according to a certain track, and finally the sum of the tracks of all the mobile LoRa gateways can cover all the LoRa terminals, i.e. each LoRa is at least covered by the communication range of one mobile LoRa gateway, and the mobile LoRa gateway can be used up as little as possible. The LoRa terminal deployment scenario is modeled as a graph g= (V, E), where V represents the set of all LoRa terminals (vertices) and E represents the set of (arc) edges between terminals. Edge between terminals (v i ,v j ) On which there is a non-negative weight d ij It is necessary to find a set of edges that can connect all the LoRa terminals into a closed loop, and make the sum of the edges of this set as small as possible;
step S12, randomly selecting a terminal i as the starting point of the moving track, and selecting a weight d from the edges connected with the starting point ij The smallest side is used as a first section of moving track, the terminal j is used as a second moving point, and a closed loop L formed by all terminals can be obtained by analogy, and the sum of the side weights is smaller;
and S13, calculating the length L of the closed loop L, wherein the length L/k+/-S of the moving track of each moving LoRa gateway is the length of the track at the terminal. For example, the length of the moving track is 100m, but the coordinates of the terminals adjacent to the track end point are 80m and 150m respectively, so that the moving track is terminated at the terminal at 80m, namely at the terminal near the track end point, and the terminal at 150m is used as the moving track start point of the next moving LoRa gateway, so that k moving LoRa gateway tracks can be formed. Each LoRa terminal selects the mobile LoRa gateway to which the nearest track belongs as the gateway responsible for its data transmission. After the track planning and the communication area division are completed, the mobile gateway only needs to reach the designated position at the designated time, and data corresponding to the LoRa terminal are collected. If the transmission starting time of a certain number of times of the mobile LoRa gateway is 10:00, the moving speed is 10m/s, and if a certain LoRa terminal distance is 100m from the starting point, the moving LoRa gateway needs to be 10: about 10 (the accurate time is influenced by the communication time in the range of 0-100m and environmental factors) into the communication range of the terminal.
And S2, because the movement of the mobile gateway has uncertainty and cannot accurately reach a certain position at a certain moment, the LoRa terminal needs to sense the arrival of the mobile LoRa gateway with low power consumption, and then performs data transmission after confirming the arrival of the mobile LoRa gateway. In offline application, the LoRa terminal is in a dormant mode when no communication is needed, wakes up in advance at the time appointed with the mobile gateway, and enters a channel activity detection mode to sense the arrival of the gateway with low power consumption;
in the off-line application, the LoRa terminal is in a dormant mode when no communication is needed, wakes up at the time point when data needs to be sent, can set the communication time between the LoRa terminal and the mobile gateway in advance, wakes up in advance before the communication point to enter a channel activity detection (Channel Activity Detection, CAD) mode to monitor the arrival of the mobile gateway. Setting the communication time point as 10:00, the mobile LoRa gateway will be at 10: around 00 (the exact time is affected by the communication time in the range of 0-100m, and environmental factors) moves into the communication range of the LoRa terminal and sends a downstream data packet for the terminal to instruct the terminal to send data with specified transmission parameters. Considering the uncertainty of time offset and gateway movement, the LoRa terminal is at 9:55 wake up from SLEEP mode and enter CAD mode to start listening for mobile gateway arrival;
step S22, when the arrival of the mobile LoRa gateway is monitored, the LoRa terminal enters a Receiving (RX) mode to receive a downlink data packet sent by the mobile LoRa gateway, the downlink data packet of the LoRa terminal comprises transmission parameters which should be used by the LoRa terminal to send an uplink data packet, and the mobile LoRa gateway calibrates time with the LoRa terminal when communicating each time, so as to reduce time errors as much as possible.
S3, after entering the communication range of the LoRa terminal, the multi-mobile LoRa gateway performs data collection with the LoRa terminal by using the transmission parameters which can realize communication, do not generate transmission conflict and have the lowest power consumption, and after receiving the instruction of the mobile LoRa gateway, the LoRa terminal performs data transmission with the mobile gateway according to the transmission parameters indicated by the mobile LoRa gateway;
after the arrival of the mobile gateway is perceived by the LoRa terminal in a low-power consumption manner, data transmission is carried out according to an instruction issued by the gateway, and the step can be divided into two parts of the mobile LoRa gateway and the LoRa terminal, and the specific process is as follows:
and S31, after entering the communication range of the LoRa terminal, the mobile gateway communicates with the LoRa terminal by a certain transmission parameter. The transmission parameters are set as follows: and the Spreading Factors (SF) of each LoRa terminal are fixed and the same, the Transmission Power (TP) of each LoRa terminal is fixed, and the SF and TP combination which meets the communication requirement and consumes the least transmission power is selected according to the perpendicular line distance between the LoRa terminal and the track/communication position of the mobile gateway. For example, when the communication distance is 100m, the combination of SF8 and TP5 can reach the communication distance, and the energy consumption is 0.01187J; the combination of SF9 and TP2 can also achieve this communication, but the power consumption is 0.02117J, so the combination of SF8 and TP5 is chosen. Due to the dense deployment of the LoRa terminals, there may be a large number of LoRa terminals in the communication range of the mobile gateway, and Channels (CF) of the terminals need to be allocated to avoid transmission collision. Under the condition that SF and TP are fixed, aiming at the condition that terminals using the same SF are densely distributed, carrying out data transmission in the same batch of every 8 LoRa terminals, adopting a random distribution mode for CF of the 8 terminals, carrying out communication of the second LoRa terminals after the first batch is finished, and carrying out communication of the rest LoRa terminals;
step S32, after entering the communication range of the LoRa terminal to be communicated, the mobile gateway transmits a downlink data packet containing channel configuration information (such as transmission parameter setting, transmission time calibration and LoRa terminal Dev ID) to the corresponding LoRa terminal;
step S33, the LoRa terminal monitors the LoRa signal sent by the mobile gateway in the CAD mode with low power consumption, if the related signal sent by the mobile gateway is monitored, the mobile gateway is indicated to reach the communication range of the terminal, and the data of the terminal are to be collected, so that the terminal is converted from the CAD mode to the Receiving (RX) mode;
step S34, after the LoRa terminal receives the downlink data packet sent by the mobile gateway in the RX mode, if the downlink data packet contains information aiming at the LoRa terminal, the LoRa terminal can transmit data in the communication, and the terminal enters a Transmission (TX) mode to start uploading data; if the downlink data packet does not indicate the terminal, the terminal reenters an RX mode until receiving the downlink indication data packet for the terminal;
step S35: and after finishing data transmission, the LoRa terminal SLEEPs, enters a SLEEP mode from a TX mode, and starts to sense the arrival of the mobile LoRa gateway with low power consumption from the SLEEP mode to a CAD mode when the communication of the next period starts. And the mobile gateway performs data collection of the next lot of LoRa terminals, and moves according to the track planned in advance until the mobile gateway enters the communication range of the next lot of LoRa terminals needing communication.
Therefore, the working flow of the LoRa terminal in the low-power consumption data transmission method of the LoRa terminal based on the multi-mobile LoRa gateway is shown in figure 2. When the LoRa terminal has data transmission requirements, waking up from a SLEEP mode, if the LoRa terminal is in online application, directly entering a TX mode to send a short prompting signal of communication requirements at the maximum communication distance, and then entering a CAD mode to monitor an arrival signal of a mobile LoRa gateway; if the mobile LoRa gateway is offline application, the mobile LoRa gateway directly enters a CAD mode to monitor the arrival signal of the mobile LoRa gateway. After monitoring the arrival signal of the mobile LoRa gateway, the LoRa terminal enters an RX mode, and if the received downlink data packet contains data transmission information aiming at the LoRa terminal, the LoRa terminal enters a TX mode to transmit data; if the data transmission information aiming at the LoRa terminal is not contained, the LoRa terminal monitors the downlink data packet sent by the LoRa gateway again until the information aiming at the LoRa terminal is received. After the data is sent, the LoRa terminal re-enters the SLEEP mode until the next time the data is required to be transmitted, and wakes up from the SLEEP mode.
And S4, in the online application, the LoRa terminal sends the uplink request data packet to the network server through the mobile LoRa gateway, and the network server synthesizes the uplink data packet of the LoRa terminal, and schedules the appropriate mobile LoRa gateway to approach the appointed LoRa terminal in real time according to a certain track and provides data transmission service for the mobile LoRa terminal.
In the online application, the LoRa terminal wakes up from the SLEEP mode when there is an uplink request because the LoRa terminal cannot agree with the mobile gateway in advance, and needs to send a short message with the maximum transmission parameters (TP, SF), where the short message includes the device ID (DevID) of the LoRa terminal, the geographic location information (GPS), the length of the data packet to be uplink, and so on. After informing the mobile LoRa gateway in the maximum communication range that the data collection requirement exists, entering a channel activity detection mode;
in the step S42, in the online application, after the mobile LoRa gateway receives the short prompt data packet of the LoRa terminal in the communication range, the data packet is forwarded to the network server. The network server can obtain information (including geographic position, data packet size and the like) of the LoRa terminal to be communicated according to the short prompt data packet sent by the LoRa terminal, and schedule the mobile gateway with the largest R value to be close to the LoRa terminal according to the following formula, wherein R=k.1/D+ (1-k) E, D is the communication distance between the mobile gateway and the LoRa terminal, E is the residual electric quantity of the mobile gateway, and k is the weight of the communication distance and the electric quantity of the mobile gateway, which can be set by a user according to application requirements. After the data transmission is completed, the mobile LoRa gateway can stop at the current communication position or the appointed charging station according to the application requirement and wait for the next scheduling instruction of the network server.
Therefore, the working flow of the LoRa gateway in the low-power consumption data transmission method of the LoRa terminal based on the multi-mobile LoRa gateway is shown in figure 3. If the mobile LoRa gateway is in the online application, the mobile LoRa gateway always monitors a short prompt signal of the LoRa terminal, if the short prompt signal is received, the short prompt signal is forwarded to a network server, and the mobile LoRa gateway moves to the LoRa terminal to be communicated according to an instruction of the network server; if the mobile LoRa gateway is applied offline, the mobile LoRa gateway moves to a LoRa terminal needing communication according to a pre-planned path, a moving speed and the like. After the mobile LoRa gateway moves to the position of the LoRa terminal needing to be communicated, the mobile LoRa gateway sends downlink data packets to the terminal, receives the downlink data packets sent by the LoRa terminal, and after the transmission is finished, moves to the next LoRa terminal needing to be communicated. And if the electric quantity of the mobile carrier such as the unmanned aerial vehicle is exhausted, returning to the charging pile for charging. In summary, the invention focuses on solving the problem of low battery endurance capacity of the LoRa terminal, can reduce the transmission power consumption of the LoRa terminal, prolong the battery endurance capacity of the LoRa terminal, reduce the unfairness of energy consumption among terminals and prolong the life cycle of the LoRa network. The method mainly comprises four parts, namely multi-mobile LoRa gateway task scheduling, a LoRa terminal low-power-consumption sensing multi-mobile LoRa gateway, low-power-consumption data transmission of the LoRa terminal and the multi-mobile LoRa gateway, and a low-power-consumption data transmission method in online application. Firstly, track planning and task allocation are carried out on a multi-mobile LoRa gateway according to the deployment condition of the LoRa aiming at offline application; secondly, designing a low-power consumption sensing multi-mobile LoRa gateway mechanism of the LoRa terminal based on a channel activity detection mode; then determining a transmission mechanism of the LoRa terminal and the multi-mobile LoRa gateway, mainly relating to the selection of transmission batches and channels; finally, aiming at different application requirements, the invention also supports low-power consumption data transmission in online application.
It should be noted that the foregoing merely illustrates the technical idea of the present invention and is not intended to limit the scope of the present invention, and that a person skilled in the art may make several improvements and modifications without departing from the principles of the present invention, which fall within the scope of the claims of the present invention.

Claims (8)

1. The low-power-consumption data transmission method of the LoRa terminal based on the multi-mobile LoRa gateway is characterized by comprising the following steps:
s1: determining the moving track of each moving LoRa gateway and the terminal range responsible for providing transmission service according to the deployment condition of the LoRa terminals, and setting the position of the moving LoRa gateway at the appointed moment and the corresponding LoRa terminal batch needing to perform data transmission;
s2: starting a channel activity detection mode, wherein the LoRa terminal perceives the arrival of the mobile LoRa gateway with low power consumption, and the LoRa terminal is in a dormant mode when communication is not needed, and performs data transmission after confirming the arrival of the mobile LoRa gateway;
s3: after entering a communication range of the LoRa terminal, the multi-mobile LoRa gateway performs data collection with the LoRa terminal, and after receiving an instruction of the mobile LoRa gateway, the LoRa terminal performs data transmission with the mobile gateway according to transmission parameters indicated by the mobile LoRa gateway;
s4: for online application, the LoRa terminal sends the uplink request data packet to the network server through the mobile LoRa gateway, and the network server synthesizes the uplink data packet of the LoRa terminal to complete real-time scheduling.
2. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 1, wherein: the step S1 specifically comprises the following steps:
s11: modeling the LoRa terminal deployment scenario as a graph g= (V, E), where V represents the set of all LoRa terminals, E represents the set of edges between terminals, edges between terminals (V i ,v j ) On which there is a non-negative weight d ij Determining a set of edges that can connect all the LoRa terminals into a closed loop, and making the sum of the edges of the set as small as possible;
s12: randomly selecting a terminal i as a starting point of a moving track, and selecting a weight d from edges connected with the starting point ij The smallest side is used as a first section of moving track, the terminal j is used as a second moving point, and a closed loop L formed by all terminals can be obtained by analogy, and the sum of the side weights is smaller;
s13: calculating the length L of a closed loop L, wherein the length of a moving track of each moving LoRa gateway is L/k+/-s, s is the length of the track at the position where the track just ends and the terminal, and k is the number of the moving LoRa gateways; and (5) completing track planning and communication area division.
3. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 1, wherein: the step S2 specifically comprises the following steps:
s21: in the off-line application, the communication time between the LoRa terminal and the mobile gateway is preset, and the LoRa terminal wakes up in advance before a communication point to enter a channel activity detection mode to monitor the arrival of the mobile gateway;
s22: when the mobile LoRa gateway is monitored to be reached, the LoRa terminal enters a receiving RX mode to receive a downlink data packet sent by the mobile LoRa gateway, wherein the downlink data packet for the LoRa terminal comprises transmission parameters which should be used for sending an uplink data packet by the LoRa terminal.
4. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 3, wherein: in step S22, each time the mobile LoRa gateway communicates, it performs time alignment with the LoRa terminal.
5. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 1, wherein: the step S3 specifically includes:
s31: after entering a communication range of the LoRa terminal, the mobile gateway communicates with the LoRa terminal, wherein the spreading factor SF of each LoRa terminal is fixed and the spreading factor SF is the same in the transmission parameters of the communication, and the transmission power TP of each LoRa terminal is fixed;
s32, the mobile gateway transmits a downlink data packet containing channel configuration information to the corresponding LoRa terminal; the channel configuration information at least comprises transmission parameter setting, transmission time calibration and a LoRa terminal Dev ID;
s33: the LoRa terminal monitors the LoRa signal sent by the mobile gateway in the CAD mode with low power consumption, if the related signal sent by the mobile gateway is monitored, the mobile gateway is indicated to reach the communication range of the terminal, the data of the terminal are to be collected, and the terminal is converted from the CAD mode to the RX mode;
s34, after the LoRa terminal receives the downlink data packet sent by the mobile gateway in the RX mode, if the downlink data packet contains information aiming at the LoRa terminal, the LoRa terminal can transmit data in the communication, and the terminal enters a transmission TX mode to start uploading data; if the downlink data packet does not indicate the terminal, the terminal reenters an RX mode until receiving the downlink indication data packet for the terminal;
s35: and after finishing data transmission, the LoRa terminal SLEEPs, enters a SLEEP mode from a TX mode, starts a low-power consumption sensing mobile LoRa gateway from the SLEEP mode to a CAD mode when the communication of the next period starts, and the mobile gateway performs data collection of the next LoRa terminal and moves according to a track planned in advance until the mobile gateway enters the communication range of the next LoRa terminal needing communication.
6. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 5, wherein: in the transmission parameters in step S31, under the condition that the spreading factor SF and the transmission power TP are fixed, for the dense distribution of the terminals using the same spreading factor SF, the same batch of 8 LoRa terminals is adopted to perform data transmission, the random distribution mode is adopted for the channels CF of the 8 terminals, the communication of the second batch of LoRa terminals is performed after the end of the first batch, and the communication of the remaining LoRa terminals is similar.
7. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 6, wherein: the step S4 specifically includes:
s41: the LoRa terminal sends short prompt information by using the maximum transmission parameters (TP, SF) to inform the mobile LoRa gateway in the maximum communication range that the data collection requirement exists, and then enters a channel activity detection mode; the short prompt message at least comprises a device ID (DevID) of the LoRa terminal, geographic position information (GPS) and the length of a data packet to be uplink;
s42: after receiving the short prompt data packet of the LoRa terminal in the communication range, the mobile LoRa gateway forwards the data packet to the network server, and the network server acquires information of the LoRa terminal needing to be communicated according to the short prompt data packet sent by the LoRa terminal, stops at the current communication position or the appointed charging station according to the application requirement after completing data transmission, and waits for the next scheduling instruction of the network server.
8. The low power consumption data transmission method for a LoRa terminal based on a multi-mobile LoRa gateway as claimed in claim 7, wherein: in step S42, the mobile gateway with the largest R value is scheduled to be close to the LoRa terminal according to the following formula, where r=k·1/d+ (1-k) ·e, D is the communication distance between the mobile gateway and the LoRa terminal, E is the remaining power of the mobile gateway, and k is the weight of the communication distance and the power of the mobile gateway set by the user according to the application requirement.
CN202310656751.8A 2023-06-05 2023-06-05 Low-power-consumption data transmission method for LoRa (virtual local area network) terminal based on multi-mobile LoRa gateway Pending CN116567788A (en)

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