Research Of Energy-saving Strategies For Urban Railway Wireless Sensor Monitoring Networks

In recent years, with the continuous development of urban rail transit system, in the process of urban rail train running, in order to reduce accidents, and guarantee the safe running of the train, it has become the key problem of urban rail train safety monitoring system that how to monitor parameters of train critical equipment in real time and reliably.This dissertation focuses on the research and exposition of energy-saving strategies for urban rail train sensor monitoring system based on wireless sensor network technology. Aiming at urban rail train wireless sensor monitoring network, through reasonable and effective energy-saving strategy, while reducing the energy consumption of the single node, also greatly extending the life cycle of the entire network, in order to better ensure the normal and stable running of the urban rail train wireless sensor monitoring system, and this has important theory research and practical application significance.Firstly, this dissertation introduces the research background, application value and overseas and domestic research status, then analyzes energy consumption aiming at sensor monitoring network architecture, and studies the related energy-saving strategy, on this basis, compares each unit of sensor node to complete component selection, and carries on the further research on the sensor monitoring network energy-saving strategy from the two aspects of hardware design and software design. The author mainly work as follows:(1) Analyzing the energy consumption distribution characteristics of urban rail train wireless sensor monitoring network, determine the main source of energy consumption (data processing and data transmission), aiming at the main source of energy consumption, formulating the corresponding strategy from the four aspects of network topology, data processing unit, wireless communication unit, and software design.(2) Based on the corresponding node energy-saving strategy, in the design of low-power sensor monitoring node, through the comparison and analysis, completing the comparison and selection of network topology and low-power components of the sensor monitoring node.(3) In the hardware energy-saving design, the system selects C8051F996microprocessor as the data processing unit of node, nRF905RF chip as the wireless transceiver unit of node, DS18B20digital temperature sensor as the sensor unit of node, EF702338square lithium battery of EVE brand as the direct power supply unit of node. In the physical device used on the low-power sensor node, further reduces energy consumption.(4) In the software energy-saving design, on the basis of completion of the node hardware platform structure, writing the point to multipoint system communication protocol, making the brief system communication data frame structure, in order to reduce the communication overhead and the energy consumption of node, Achieving the energy-saving strategy of node (work-sleep periodic alternating transformation mechanism) and the work process design of low-power node.(5) Finally, on the basis of the completion of the node software and hardware energy-saving design, to the reliability and availability of communication platform, especially the energy-saving characteristic, making experimental validation, the experimental results show that the proposed urban rail train monitoring wireless sensor network energy-saving strategy can achieve expected goal, saving the battery of sensor monitoring node, extending the life cycle of the entire network, having quite profound theoretical and practical significance.