Research On An Improved Distance Threshold Pegasis Protocol For Wireless Sensor Network

With the rapid development of wireless sensor technology, now it can collect information and process queries more powerfully. The rapid development of wireless sensof technology promotes the development of wireless sensor networks in many fields, such as environmental monitoring, military surveillance, health care, vulnerability, transportation management. industry, agriculture, scientific research, and other applications. As one of the key technologies for wireless sensor networks, wireless routing protocol technology becomes a hot research topic in the field of telecommunication and computer science.A WSN is always composed of a large number of small sensor nodes, which collaborate with each other to accomplish the information perception, acquisition, transmission and other tasks. In order to complete the assigned tasks, wireless sensor nodes need to collect and transfer the information about the environment. Routing technology plays an important role in the WSN. Because the WSN has characteristics of constrained energy, local-based and frequently-changed topology, data-centric and application-oriented architecture, the design of routing protocol for wireless sensor networks will have a very critical impact on the performance of the whole WSN. This poses many new challenges for the protocol designers.In order to solve the problems mentioned above, the cluster-based hierarchy routing protocols (for example. LEACH. PEGASIS protocol), especially the PEGASIS protocol, are indepthly studied in this paper. PEGASIS protocol is actually the improvement of LEACH, it is a typical protocol which can effectively reduce the energy consumption of the WSN. PEGASIS protocol reduces the overhead of LEACH protocol in the process of cluster reconstruction, and reduces the number of times in data sending and receiving process by data fusion technique. Then energy efficiency is achieved by transmitting the data to only one of its neighbor node. In this way, it reduces the energy consumption. But the essence of PEGASIS protocol is to put all of the nodes into a chain in order to transmit data. So how to build a better chain will directly influence the performance of this protocol. While building a chain, PEGASIS uses the greedy algorithm. So there exist many problems in the selection of the first node of a chain and in the local optimization.In order to solve the problems mentioned above, an improved distance threshold PEGASIS protocol, DT-PEGASIS, is designed in this paper. During the chain building process, in order to avoid choosing too long distance for neighbor nodes, DT-PEGASIS set a distance threshold for all of the nodes. While a node is in the search for its next hop neighbor node, it will rebuild a new chain if the distance between these two nodes is longer than the distance threshold. With the constraint of the distance threshold, all of the distances between nodes and its neighbors will not too long. In this way, it can avoid a locally long chain effectively. This will not only extend the lifetime of the whole WSN, but also balance the energy consumption of each node.In order to verify the performance of DT-PEGASIS, it is designed and implemented in NS2(Network Simulator version2). Simulation tests for DT-PEGASIS are carried out under a variety of different scenarios, and the results are compared with PEGASIS protocol. We can conclude that DT-PEGASIS protocol can significantly prolong the lifetime of WSNs and balance the energy consumption of each node.