The Research Of Routing Protocol Based On QoS For Wireless Sensor Networks

Wireless Sensor Network has been applied to many aspects. It can be used to monitorpatients who have suffered from special diseases efficiently and to prevent the disease fromspreading. Also, during the war, sensor can be distributed in the rear of the enemy to collectmilitary intelligence.Thus, we can reduce casualties. Furthermore, millions of sensor nodesare deployed in a large and poor-conditioned forest to provide real-time messages and toconfirm fire or chemical spills in contaminated area. In addition, for home applications, WSNcan make it possible for the user to do some remote housework via Internet. In order toprovide a better service for these applications, Quality of Service is regarded as one of the keyfactors that need to be considered while designing the WSN routing protocols.This paper proposes two kinds of improved routing protocols, based on the study ofWSN and QoS based routing protocol for WSN.The first protocol is LEACH-QoS. It is an improvement of LEACH protocol as well as akind of hierarchical routing protocol. It makes full use of the advantages of LEACH in termsof energy consumption and introduces the “cluster head index” to the process of the selectionof a cluster head. The base station can control the selection of a cluster head by reference tothree parameters:“cluster head index”, the average energy and the optimal number of clusterheads, aiming to make full use of network resources. And then, the cluster head makes acomparison of the current energy among all the nodes in the cluster and chooses the largest asa secondary node, which will share part of the responsibility of the cluster head. This processbalances the energy consumption of the network, thus it can avoid the premature death ofcluster head nodes, and prolong the working hours of the network. In the process of clusterorganization, Let us draw a circle with the cluster head as the center and checkingsemi-diameter R proposed in DC-LEACH as semi-diameter. All the nodes within the circlebelong to this cluster. This method can optimize the division of the clusters. This protocolalso combines single hop, thus it can meet different requirements for time delay. Thesimulation results show that LEACH-QoS protocol is better than LEACH and DC-LEACHprotocol in prolonging network lifetime and satisfying the requirements for time delay.Another improved protocol is DG protocol, a flat routing protocol. In route discoveryphase, the discovery of the next-hop node is based on the value of time-delay function, whichis determined by the energy and time-delay parameters. Thus, to a certain degree, it can makesure that the established path can satisfy the requirement of network for the two parameters.Nodes, which have less energy, are marked in this protocol and this method can simplify theprocess of establishing the routing. The “candidate next-hop node” could shorten the path establishment time. Simulation results show that, compared with the SAR protocol, the timedelay of the networks that use the DG protocol is shorter and the lifetime is longer.