Research On Techniques Of Network Topologyandad Hoc Network In Cold Chain Transportation Monitoring System

Due to the characteristics of cold chain transportation monitoring which arecentralized supervision, local distribution and overall mobility, nodes which are lowpower consumption and tiny，and network architecture which is stable and of strongantijamming ability are demanded. According to practical demands，a cold chaintransportation monitoring system is designed. The system consists of data acquisitionnode, data transfer node, and remote server.Firstly, a two level wireless star network is designed.The first level is GPRSnetwork,which is used to connect remote server and data transfer node.The secondlevel is wireless sensor networks,which is used to connect data transfer node and dataacquisition node,and to realize ad hoc networks. Aiming at the characteristics of coldchain transportation environment,an independent network protocol is defined, whichis low power consumption and of strong antijamming ability. A new kind of networkanti-collision algorithm is given which fused and developed binary tree algorithm andframe time-slot aloha algorithm.It can efficiently reduce network impacts,and canensure fast and efficient network.Secondly, the software and hardware design of data transfer node is given andrealized. Data transfer node uses STM32microprocessor as main controller; usesGPRS module to upload data to server; uses wireless module based on SX1212chipto ad hoc network; uses GPS module to gather vehicle’s location; and uses TF card toback up data.The software program is designed with task mode, to increase thereadability of program,and to contribute to later period management and addingfunctions.According to the test results, the system runs stably, while it is safe andenergy-efficient.The two level network is stable and reliable. Independent networkprotocol is safe and energy-efficient, and suitable for cold chain transportationenvironment. The system can monitor temperature and humidity, battery capacity, and transit route, to reduce transportation loss, and to ensure smooth and safe operation ofcold chain transportation.