| The wireless sensor network is formed by a large number of low cost sensor nodes with wireless communication function.It can realize,collect and process information in the network area,and has the characteristics of fast expansion,high monitoring precision and fault tolerance.It is a new information access platform,which has been widely used in military,agriculture,environmental monitoring,medical,logistics and other fields.Wireless sensor network is the basis for many applications in the industrial internet of things,the research on the wireless sensors and products of wireless sensor networks is becoming more and more important.Localization is one of the key technologies and basis in wireless sensor networks.However,in the real environment,the localization accuracy will be greatly influenced when we take the radio range irregularity and node failure into consideration.Therefore,in this paper,based on the implementation of the original DV-Hop localization algorithm and two variations,we investigate the impact of irregular radio and faulty sensors on the performance of localization.By this investigation,the obtained conclusion can be used to direct localization algorithm design under a more realistic scenario and provides better parameter configuration for a given WSN.The main work of this thesis is summarized as follows:1.The wireless sensor network was briefly introduced in chapter 2,and an overview of the industrial wireless sensor network was given.2.In chapter 3,the classical distributed and non-ranging DV-Hop localization algorithm is studied in detail.The original DV-Hop localization algorithm and two variations are implemented on a Java-based wireless sensor network simulation and visualization software which is called NetTopo under the ideal conditions.3.In chapter 4,a large number of experiments are conducted in WSNs' simulator NetTopo to study the problem of low localization accuracy which comes from the situation of irregular radio and random faulty sensors in the real environment.This chapter designs a new system model by considering irregular radio and random faulty sensors,this model can reflect the actual environment of the radio irregularity characteristics and node failure situation.In this chapter,we firstly simulate the situation of network connectivity and coverage under different irregularity conditions.Then,due to the random failure of anchors and unknown nodes in the wireless sensor network,the localization coverage and accuracy is reduced,the position of the monitoring object can not be reported effectively.In this chapter,all the sensors in the deployment area are randomly invalid according to a certain proportion in the simulation experiment.The network connectivity and coverage under different faulty percentage are studied.The comprehensive effect of faulty node and radio irregularity on network connectivity and coverage is considered in the end.4.In chapter 5,the simulation experiments are conducted for the system model proposed in the chapter 4.Firstly,the localization errors of different localization algorithms are analyzed and compared under different radio irregularity.Then,the localization errors of different localization algorithms under different faulty node percentage are compared.Finally,the comprehensive influence of different radio irregularity and faulty node percentage on the three localization algorithms is studied.The research work of this thesis provides a reference for the future design of a more reasonable algorithm and the scientific choice of network parameters for network deployment without losing the localization accuracy and minimizing the network consumption.5.The chapter 6 summarizes the main work of this thesis,and provides the planning and the arrangement of the future research work. |
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