The Study Of Key Communication Technologies For Wireless Sensor Networks Based Electricity Tower Monitoring System

Through the deployment of micro sensor nodes on the spot, wireless sensor network transmits the information to the sink by means of self-organizing wireless network technology after data collection and processing. In order to achieve the monitoring of information on the nodes deployed area, which is especially suitable for the terrain where natural conditions are poor, it requires long-term or large amounts of data collection.Combining with the advantages of wireless sensor networks, the thesis considers high-voltage transmission lines and power towers environmental information monitoring network as the research objects, focusing on several key technical aspects of the theory and applied research, such as network structure in monitoring network, communication protocol, node hardware implement and circuit energy consumption control, the algorithms of MAC protocol and route protocol, error control transmission energy efficiency and reliability. The thesis mainly completes the following tasks.First, based on the current communication technology applied on power system and related applied research for wireless sensor network technology, it analyses the actual status of the power tower monitoring network, proposes the linear networking model of wireless sensor network used on electric tower and designs the overall and regional network systems integrated monitoring system model. From the perspective of the whole monitoring area, the characteristics of the power towers'location is linear, using mesh structure; from a single power tower point, it adopts star-shaped network structure; each cluster head of star-shaped network forms common node of mesh network, and the whole network presents a linear network features. This hybrid networking makes the deployment of sensor nodes convenient and the design of network protocol clear, especially suits for power towers as a monitored object which is special on location.Then the thesis introduces the hardware overall structure and the implementation idea to each module of power towers monitoring network, and proposes two types of design method of wireless gateway function sink-node and the general information collection sensor node. It accomplishes the design and implementation to detail circuit schematic and PCB circuit board of the main control unit module, ZigBee wireless communication module, GPRS data transmission module, video images acquisition unit module, temperature and humidity acquisition module, power management module and battery monitoring module.Third, the thesis studies and analyses wireless communication protocol of the monitoring network, and eventually comes to a conclusion that the distribution density of the power towers monitoring network nodes is small, the collected data changes relatively slow. Therefore, based on S-MAC protocol, we bring forward a new algorithm of dynamic wake cycle according to the variation of network communication flow; meanwhile, combined with hierarchical routing protocol LEACH algorithm and the advantages of DPC algorithm, based on the random selection mechanism of the cluster heads, a improved rotation route algorithm is put forward, which proceed to chose cluster heads combined with nodes power control; the new improved MAC layer protocol and network layer routing algorithm reduce the overhead of nodes, performing good.Fourth, in terms of the actual demand of power towers data collection and transmission, the article designs the data frame format of the nodes video images, temperature and humidity collection information, and puts forward the gathering on node layered nested packet encapsulation protocol design method; this method uses hierarchical nested packet encapsulation to simplify the processing of nodes monitoring data, and its top standard IP protocol used realizes remote data interconnection between sink through GPRS gateway and the Internet. Adopting standard C language, it completes the implementation and associated debugging of each hardware unit driver, node networking and data receiving & sending and wireless communication protocol procedures.Fifth, several methods of reducing the node energy consumption are studied and analyzed in the paper, from the following aspects of the node energy consumption are calculated:the dynamic changes of the channel access mode, low power consumption work patterns of CPU processor low frequency clock work, the improvement of data acquisition and processing methods and data transmission error control methods, the new way of selecting node cluster head proposed according to battery power monitoring has a obvious effect on prolonging the life cycle of nodes; simultaneously, it emphatically researches the effect estimation to reducing wireless communication module, reducing energy consumption based on the video image monitor alarm mode and data transmission FEC forward error correction ways.The thesis comes up with improved protocol algorithm and new application thought on several key technical aspects of power towers wireless sensor network, the result is feasible after verification test, lays a good foundation for further improving monitoring network.