Wireless Sensor Network Applications In Forest Microclimate Monitoring

Through the comprehensive consideration of the characteristics forest environmental and microclimate monitoring in the wireless sensor networks, standard wireless sensor network node was designed on the basis of ZigBee/802.15.4standard, localization algorithm and accuracy were improved. Based on the present RSSI energy optimization algorithm and combined with the receiving signal strength and link quality instruction parameters, which had relationship with the channel quality, and the nodes distance parameter, energy cross layer optimization algorithm was constructed to advance the lifecycle of wireless sensor networks. The sensor data fusion mechanism was built, the data quality was improved, energy consumption of nodes communication was reduced and the lifecycle of wireless sensor networks was advanced.On the basis of energy optimization, forest microclimate monitoring of sensor network function structure was designed from physical and MAC layer, and forest microclimate monitoring sensor networks structure was built based on ZigBee/802.15.4standard. According to the characteristics of the large forest microclimate monitoring range, regional geomorphic dispersion and complexity, wireless sensor network nodes and controlling nodes, which combined with ARM processor, were designed. The key technology in forest microclimate monitoring wireless sensor network was realized in the physical and MAC layer.Considering the object of study, the classical localization algorithm was improved, and a kind of large-scale sensor network location algorithm was designed to solve localization algorithm complexity of the wireless sensor network, positioning accuracy and calculation costs low energy consumption. Compared to the MDS-MAP location algorithm of classic MDS algorithm, it has the advantages of low complexity, avoiding the shortest path estimation by using a jump to calculate cluster nodes in the distance, and reducing the energy consumption. The algorithm can not only gain better positioning accuracy at the regular networks, but also can gain the lower positioning error at the irregular networks. The algorithm provided the distance parameter between the basic nodes for the design of cross layer energy, and provided the geographical position reference of data fusion.Considering the characteristic of forest environmental, a cross energy optimization algorithm was built on the basis of the nodes distance, strength instructions of receiving signal and link quality instruction by the analysis of radio wave propagation loss model and CC2520. This algorithm is suitable for the situations of low cost communication and low hardware requirement. The relevance between sending power and RSSI, LQI, the distance of the nodes was gained by piecewise linear approximation, which realized the energy optimization algorithm of cross layer among the application layer, the MAC layer and physical layer on the basis of link quality and the nodes distance. Simulation by MATLAB proved that there was obviously improvement in energy saving compare to standard data sending method. This algorithm reduced the energy consumption and the collision between the nodes, improving the sensor network of wireless sensor network life cycle and extending the monitoring cycle of forest microclimate.On the basis of above studies and data characteristics of forest microclimate monitoring, data fusion mechanism of sensor nodes combined with self-adaptive and weighting algorithm of credibility mechanism was built for the fusion of single node, adjacent nodes of similar data and the data from different clusters. The data fusion mechanism can remove redundant data, improve the accuracy and collection efficiency of the data, reduce the energy consumption in the data communication and improve life cycle of the wireless sensor network.In thesis, on the basis of above studies and data characteristics of forest microclimate monitoring, some key technologies in wireless sensor networks such as node hardware design, localization algorithm improving, cross layer energy-saving algorithm, data fusion etc. were realized, which made the wireless sensor network nodes fit for monitoring forest microclimate.