Research And Simulation Of Cluster-Based Energy Saving Routing Protocols For Wireless Sensor Networks

Wireless sensor network is a new research area of modern communication network.It can be described as an autonomy system consisting of lots of sensor nodes designed to intercommunicate via wireless radio.Wireless sensor network which is utilized in a broad foreground is able to instantly monitor,collect and process various information of environment,Recent advances in sensor technology, micro-electromechanical systems,modern network technology and wireless communications have motivated the development of wireless sensor network.It has been able to be used in many areas such as military field,space exploration,radiation detection,early warning of flood,management of fields and so on.In this thesis,it introduces the background and significance firstly and then the architecture,primary characteristic,foreground of application and pivotal technology of wireless sensor network are presented briefly.Wireless sensor network consists of a large quantity of sensor nodes whose power,calculation ability and bandwidth are so limited that traditional wireless routing protocol is not suitable for it.So designing efficient routing protocol to save energy and prolong the lifetime of the whole network is very important for wireless sensor network.Researching and designing routing protocol of wireless sensor network is the main part of this work.At first,we studied the characteristic,objective and classification of the routing protocols in wireless sensor network,Then we give the analysis and comparison of several kinds of existing protocols.LEACH protocol is elected to be the research target as the representative of the cluster-based routing protocols.In LEACH,the nodes organize themselves into local clusters,with one node acting as the cluster head.The aggregated data in the cluster heads are transmitted to the base station.The lifetime of the network is increased by selecting the head node randomly.Because of the rotational selection of head node,the energy load is evenly distributed throughout the network,which further reducing energy dissipation.But the electing of cluster head is random and equiprobable.In order to avoid to elect the lower nodes to be cluster heads and balance the energy consumption of cluster heads. Thesis look-over the residual energy of the elected cluster head possibly in the cluster set-up phase.If it can't satisfy the demand,the node with high energy will replace it. In addition,cluster head transmit information to base directly,if cluster head is not far away from the base station,LEACH will has favorable performance.By contraries, the cluster head will consume lots of energy for long distance communication.This situation will speed up the death of cluster heads and shorten the lifetime of system. In this thesis,in order to reduce the energy consumption of the cluster heads which are far away from base station and balance the energy consumption of the cluster heads which are close to base station.A multiple-hop routing algorithm of cluster heads based on LEACH is presented,which introduces into the restriction factor of residual energy when selects the interim nodes beween cluster heads and base station. When the novel algorithm constructs the minimum spanning tree including base station and all the cluster heads,it considers the residual energy of cluster heads which is choosed to be a interim node.Then a shortest multiple-hop routing is formed for inter-cluster communication,avoiding to use the cluster heads with lower energy. The thesis compares LEACH and the proposed algorithm through the simulation experiments in the NS2.Simulation results demonstrate that the proposed algorithm, compared with LEACH,is more efficient to reduce and balance energy consumption and hence prolong the lifetime of WSN.Finally,we give the conclusion of our work and suggestions for future research direction of Wireless sensor Network.