Study Of Improving Efficacy Of Wireless Sensor Networks In Orchard

Nowadays WSN(wireless sensor networks) is widely used in many areas, when it is used in agriculture and outdoor fields, the limit of costs and power resources force the improvement of energy efficiency fiercely, efficiency is the main cause of limiting the wide usage of WSN nodes.energy efficiency and communication performance are two important aspects of efficiency, the purpose of this dissertation is to improve the efficiency of WSN used in orchard.Nowadays as the data resource of foliage loss study is limited, the fitting accuracy for different spieces and frequency are various, the existing study is not fitted to orchard, so this dissertation carried out detailed anylisis and study for these models in orchard; When existing there exists problems for time synchronization protocol that what mechanisms to run to keep time synchronization in long time netwide and make the root know the status of other nodes, the existing communication protocols require the wireless module on for very long period, and the communication protocols cann’t adapt to dynamics of link quality, to resolve these problems, an entire time synchronization protocol and communication protocol are designed in this dissertation; The combination of noise ratio, link quality index and packet receive rate to measure link quality is a new trend of link quality estimator, recently the accuracy of these link quality estimators are not good enough, to resolve these problems link quality estimator that are fit to this new trend is designed in this dissertation.The contents, achievements and innovation of this dissertation is presented as followings:(1) By obtaining the path loss for peach tree in different growing stages, model fitting and evaluation, the best foliage loss model for2.4GHz signal for peach tree was found, the average of correlation coefficient of non zero model(NZG) model reaches0.942and the average mean square error was only13.2dB, this study could compensate for the lack of foliage loss prediction models evaluation studies by plants and trees.(2) In terms of improving time synchronization protocol and communication protocol accomodate to application in a peach garden, the existing time synchronization protocols and communication protocols were anlysed, then the existing time synchronization protocol and communication protocol are improved and designed, part of its robustness was tested, the result showed that the protocol could run steadly and was robust even when the root is invalid. Comparative trials between the communication protocol for peach garden and time synchronized multihop protocol were carried out in conditions that when all the conditions except for protocol are the same the average packet deliver ratio of all the nodes was12.9%higher than time synchronized multihop protocol.(3) Several link estimate metrics of wireless sensor networks were fitted with data measured in peach garden and one of them was chosen. Comparative trials showed that when all the conditions except for protocol were the same the average packet receive rate of signal to noise ratio-link quality index-packet receive rate collection tree protocol was83.1%, higher than72.5%-the packet receive rate for collection tree protocol, the average packet receive rate of time synchronized signal to noise ratio-link quality index-packet receive rate collection tree protocol was69.4%, which was higher than58.0%. The result indicated an other efficiency enhancement for the communication protocol used in peach garden.