Clustering In Wireless Sensor Network Routing Protocols

Recent advances in microprocessor, wireless communication technology and micro-electro-mechanism system, have enabled the development of wireless sensor networks (WSNs). Wireless sensor network is a novel technology about acquiring and processing information. In wireless sensor networks, lots of sensor nodes work cooperatively to gather and process information from sensor fields, with wireless communication and self-organization. Wireless sensor networks have many promise and potential applications, such as military fields, environment research, outer space exploration and business applications.Wireless sensor networks have different features comparing traditional computer networks. The sensor nodes have very limited energy supply, which greatly influences the research on routing protocols for WSNs. Routing protocols for WSNs have some new characters, and bring different design principle to researchers. So existing routing protocols for computer networks do not fit wireless sensor networks well, and new energy-efficient routing protocols should be proposed.Routing protocols for WSNs can be classified into two categories: flat routing protocols and cluster-based routing protocols. According to some common properties, this paper categorizes and compares the existing routing protocols for WSNs, and our research emphasis on routing protocols based on clustering hierarchy. The analysis of cluster-based routing protocols for WSNs shows that clustering hierarchy is an energy-efficient communication mechanism.LEACH (Low Energy Adaptive Clustering Hierarchy) communication protocol is the first routing protocol based on clustering hierarchy. This paper summarizes the basic ideas of LEACH, and analyzes the energy consumption of clusters in one round. The operation of LEACH is divided into rounds. Each round begins with a set-up phase when the clusters are organized with a fully random cluster-head election method, followed by a steady-state phase when data are transferred from the nodes to the cluster-head and on to users. Cluster-head is the control and communication center in the cluster, and consumes more energy than non-cluster head nodes. LEACH randomly selects sensor nodes as cluster-heads, and changes after certain time, so the energy dissipation of different nodes in WSNs can be balanced.