Research Of Reliable Data Delivery Scheme In Wireless Sensor Networks On Multi-scenarios

Wireless Sensor Networks(WSN)fuse information perception,processing,transmission and other functions as one.Data delivery scheme is responsible for sending the collected data to sink nodes.WSNs are usually made up of low-power and simple function nodes.And the nodes use multi-hop wireless channel to communicate with each other.The data transmission quality is susceptible to the variation of network traffic,the interference of radio link,the mobility of nodes and other uncertainty factors of network.Therefore,Design and optimization of the data delivery scheme is one of the key methods to enhance the overall performance of WSNs,which determines the availability,reliability and overhead of the transmitting process.In this paper,reliable data delivery schemes under different scenarios are studied.In event-driven application scenario,due to burstiness of network traffic,the core problems of research are timely awareness of congestion status change,path creation with congestion avoidance and appropriate reliable data transmission method.In the delay tolerant network scenarios with intermittent connectivity,node mobility makes it difficult to maintain the transmission path from end to end.The core problems are timely awareness of the link changes in space-time dimensions,prediction of reliable transmission path and reliable data transfer methods.The mainly research goals are to ensure reliability while reducing transmission delay and transmission overhead.Focusing on the core issues of these two scenarios,the dissertation makes the following contributions:(1)Event driven wireless sensor networks has the characteristic of traffic bursting which lead to the congestion in local area and affect the reliability of data transfer.To solve this problem,through theoretical modeling,three kinds of reliable data transfer mechanisms are systematic analysis and comparison which are hop-by-hop retransmission,redundancy multi-path and network coding.A method of region congestion detecting based on neighbor nodes congestion degree is proposed which can response congestion status of local area more quickly.At last,a network coding based congestion aware reliable routing protocol(NCCAR)is proposed.Simulation results show that,NCCAR can reasonably avoid congested areas,and estimates the source number of packets according to the link reliability.The data transmission reliability is improved in event-driven wireless sensor networks.(2)To reveal the effect of different data transfer mechanism on the transmission performance in delay tolerant mobile sensor networks(DTMSN),according to the characteristics of the message state transition,a semi-Markov process based messages state transition model is proposed.Under this model,the performance analytical framework of transmission mechanism is established.Under the condition of exponentially distributed of inter-meeting time,the message delivery delay and transition probability are deduced.And through experiments,message delivery delay and transition probability of these schemes are compared,which provide a theoretical basis for improving the reliability of data delivery scheme in DTMSN.(3)Facing the delay tolerant sensor networks with people carrying sensor nodes,based on analyzing the community characteristics of mobile trajectory,a heterogeneous community structure network model is established.Under the community network model,data delivery probabilities of multi-copied delivery were deduced.We propose a community based multi-copy data delivery scheme(CMDD).By dynamically computing the average inter-meeting time between the communities and using the delivery probability formulations,the scheme can estimate the delivery probability when data are delivering through such community.Simulation results show that the proposed CMDD scheme achieve a relatively high data delivery ratio and a lower message delivery latency and transmission overhead.(4)Based on analyzing the spatial and temporal characteristics of human trajectory,a mobility aware model and contact prediction method are proposed for DTMSN.In order to describe the uncertainty of nodes contacts in the scenario with inadequate spatio-temporal information,the uncertainty theory of interval number is introduced and a method of comparing contacts probability is proposed.On this basis,a prediction assisted dynamic multi-copy data delivery mechanism(PADMD)is proposed.Simulation results show that the proposed scheme achieves a relatively high data delivery ratio and reduces the end to end delivery latency.