LoRa-based Linear Wireless Sensor Network Monitoring System

Linear sensor network has certain application scenarios,such as road monitoring,long pipeline monitoring for transporting oil,natural gas and water resources,river environment monitoring,etc.The sensor nodes in this network are distributed in a linear or semilinear topology,which usually requires longer transmission distance and lower energy consumption.LoRa WAN is widely used in information monitoring under star topology due to its advantages of wide transmission distance,flexible networking and low power consumption.However,using LoRa WAN in linear topology scenarios requires the introduction of a large number of gateways,which will lead to information asymmetry,energy waste and low network utilization.This study proposed a new LoRa-based WSN monitoring system with linear topology,which is mainly composed of several sensor monitoring nodes and gateway nodes.Among them,sensor monitoring nodes communicate with LoRa protocol and collect data to gateway nodes,which transmit data to the cloud through Narrow Band Internet of Things.All nodes are built with SX1278 chips with ultra-low receiving sensitivity and arranged in a linear topology.At the same time,low power consumption wake-up and network construction were realized through Channel Activity Detection.In addition,in order to improve the robustness and fault tolerance of the system,a special transmission method was adopted to locate the fault node.The main work of this paper is as follows:(1)A wireless sensor network monitoring system for linear topological scenarios is designed and completed.From the LoRa terminal to the LoRa gateway with the function of information transmission between networks,and finally the server cloud platform which can be used for human-computer interaction,a complete linear sensor network monitoring system solution is presented.(2)Strong node scalability.The nodes of the system are networked through the combination of LoRa multi-hop and channel activity detection algorithm,which makes the system have strong node scalability.As long as the address of LoRa terminal node is modified,the system network can be joined.Theoretically,the number of sensor nodes can be increased arbitrarily.(3)Ultra low power consumption design.First,the system is put to sleep most of the time through a duty cycle strategy.Then,according to the functions of the nodes,the working modes of MCU and RF transceiver are reasonably matched to reduce the energy consumption of the nodes as much as possible.Finally,the MOS tube circuit of model D4184 is used to control the on-off power supply of the sensor.When the information of the sensor needs to be read,the sensor will be powered.(4)Universal LoRa terminal design.LoRa terminal has reserved 8-channel ADC and1-channel RS485 bus interface,which can be compatible with a variety of industrial sensors.Different types of sensors can be selected according to requirements to achieve different terminal functions.Interactive devices such as touch keys,LED indicator lights and OLED displays are installed on the system nodes to change key parameters of Lora,display system information and debug the system.(5)LoRa to NB-Io T gateway design.The gateway adopts the combination of LORA and NB-Io T technology,which not only reduces the cost and power consumption,but also enhances the flexibility of the system.This way can also avoid the remote mountain area power supply is not convenient and solve the problem of communication blind areas.In summary,the monitoring system proposed in this paper fully realizes the functions of information collection,transmission and interface display,and has the characteristics of low cost,low power consumption,long transmission distance,rich LoRa terminal interface and strong system scalability.The system is suitable for the application scenarios of linear topology structures such as riverside hydrological monitoring,oil pipeline monitoring and long distance railway monitoring.