Research On Key Technology Of Coverage Hole And Data Collection For Wireless Sensor Networks

Wireless sensor networks,which are an important part of framework infrastructure of Internet of Things,have wide application prospect.The basic function of wireless sensor networks is to collect data from monitoring area,collecting complete data from the monitoring area and reliable transmission to the user center are very important,which determines the response speed and reliability of network application.However,energy,storage space,computation and communication capacities of sensor nodes are limited.Furthermore,there are the problems of coverage holes and unreliable links in wireless sensor network.Faced with these problems,the research work of the dissertation are exploring how to design the effective data collection technique that can not only achieve energy-efficient,but also meet the requirements of low delay and high collection rate in data collection.The research work are summarized as follows:(i)Research on detection and reparation of coverage hole for wireless sensor network.To deal with the degradation of network coverage quality of service and incomplete data collection caused by coverage holes,the dissertation firstly proposes a coverage hole detection algorithm based on relative position of link intersections,named CHDARPI.By utilizing hole detection message forwarding strategy based on node's direction angle,CHDARPI makes it possible to simultaneously increase the speed for detecting coverage holes and reduce the energy consumption for detecting coverage holes.Furthermore,aiming at the NP-hard problem of coverage holes complete repairing,the dissertation proposes a distributed coverage hole repairing algorithm based on non-parallel dichotomy,named CHRAND,which is able to ensure that mobile node can repair the maximum coverage area by choosing optimal position based on arc dichotomy.Compared with the existing methods,experimental results show that detection time and energy consumption of CHDARPI decrease on average by 15.2% and 16.7% respectively,repairing ratio of CHRAND reaches 100% and its repairing redundancy is no more than 0.354.(ii)Research on energy-efficient routing protocol for wireless sensor networks with unreliable link.To cope with the reduction of data collection ratio caused by unreliable links,this dissertation proposes an energy-efficient dynamic routing protocol,named EEDRP,which employs the packet reception ratio to evaluate the link quality and constructs the sort forwarding set by using active state time slot of neighbor nodes.Aiming at the shortcoming of EEDRP in scalability,this dissertation proposes an unequal clustering protocol based on fuzzy logic oriented to unreliable links,named UCPFLUL.After analyzing the causes of energy hole in clustering protocol,UCPFLUL designs the methods of cluster head election,cluster radius decision,distributed clustering and inter-cluster routing to transmit data reliably.The experimental results show that when comparing to existing methods,EEDRP and UCPFLUL can effectively reduce the energy consumption of sensor nodes,and their data collection ratios are above 88%.(iii)Research on low latency data collection for banded wireless sensor network with mobile Sink.In banded wireless sensor network,the traditional mobile Sink data collection methods cannot meet the low delay performance requirement of data collection for event monitoring,the dissertation proposes a data collection algorithm based on forwarding of agent node,named DCAFAN.After constructing the agent node queue which depicts the Sink mobile trace and the line node sequence that stores the tracking agent node,nodes transfer data to Sink by acquiring the tracking agent node.Extensive experimental results show that DCAFAN can effectively reduce the delay of data collection,balance energy consumption of nodes and improve data collection ratio.(iv)Research on path planning of mobile devices for resource-constrained wireless sensor networks.To solve the low collection ratio and large collection delay caused by scheduling of mobile devices jointing data collection and wireless charging,the dissertation establishes a path planning model of mobile device,proves that the problem of path planning of mobile devices is a NP-hard problem,and proposes a path planning algorithm of mobile device based on greedy strategy,named PPAGS,which estimates the minimum stopping time and maximum waiting time of mobile devices based on markov model to optimize the mobile path of mobile device.Compared with the existing methods,extensive experimental results show that data collection ratio increases by 7% up to 98.91%,data collection delay decreases by 25.9% and node failure ratio is no more than 3.1% in PPAGS.