Research On Energy-efficient And Reliable Routing Protocols In Wireless Sensor Networks

Wireless Sensor Networks(WSNs),as a new research field,have got more and more attention from the academia and industry because of their wide practical application value and scientific research significance.However,the wireless channel affected by the change of the external environment will lead to the unreliability of the data transmission among the sensor nodes.In addition,the nodes in wireless sensor networks are mostly powered by non-rechargeable batteries.Frequent replacement of batteries will increase the cost of wireless sensor networks.Therefore,how to design an effective routing protocol to ensure the reliable transmission of data and the efficient use of energy has been the key issue in the research of wireless sensor networks.Two network models for “one-source one-sink” and “multi-source one-sink” cases are studied in this thesis,i.e."one to one" and "many to one" networks.From the two aspects of path finding and data transmission,this thesis discusses how to use the node energy effectively and improve the reliability of data transmission.The main research contents are as follows:(1)In the "one to one" wireless sensor networks,there are some problems of the inefficient data transmission and large energy consumption in the traditional routing protocols.In order to reduce the "redundancy" and "retransmission" phenomena in the process of data transmission,a network coding based geographical routing protocol is proposed in this paper.In the stage of path establishing,a cluster is regard as a basic unit of data transmission,and both the number of nodes in each cluster and its geographical location information are comprehensively considered,which can balance the energy consumption among the clusters.In the data transmission stage,the network coding and cooperative communication technologies are combined to reduce the effect on network robustness which is caused by node failure and energydepletion,thereby improve the successful delivery rate of data.Theoretical analysis and numerical results show that the proposed protocol can significantly increase the reliability of data transmission and reduce the energy consumption of nodes.(2)For the problems of " poor reliability of nodes far away from the sink and heavy load of nodes close to the sink " in the data transmission phase in "many to one" wireless sensor networks,the heterogeneous candidate node set based opportunistic routing protocol is proposed by combining the opportunistic routing strategy with node itself geographical position information.In the stage of candidate nodes selection,the sender uses its own location information to determine the constraints of direction and angle.By adjusting the size of the area,the goals of enhancing the packets transmission reliability and reducing the energy consumption of the nodes can be achieved.At the same time,using opportunistic transmission strategy reduces the failure rate of data transmission.The simulation results show that the proposed protocol can not only effectively reduce the energy consumption of nodes,but also prolong the network lifetime.