Abstract—One of the major issues in wireless sensor network is developing an energy-efficient routing protocol. LEACH is very effective in enhancing lifetime of the nodes from routing aspect. This paper proposes the scheduling of energy efficient cluster nodes close to the base station called EECL algorithm. Both LEACH and EECL algorithms have been varied with different transmission radii and compared for the improvement of network lifetime. Simulation results show that there has been significant improvement in energy conservation of wireless sensor networks with EECL. Index Terms—WSN, data aggregation, network lifetime, EECL, transmission radius. I. INTRODUCTION Wireless sensor networks (WSNs) usually contain thousands or millions of sensors, which are randomly and widely deployed. Sensors are powered by battery, which cannot rechargeable after deployment. But sensor networks are designed to last. Sensor nodes collaborate to be able to cope with the environment: they operate completely wirelessly, and are able to spontaneously create an ad hoc network, assemble the network themselves, dynamically adapt to device failure and degradation, manage movement of sensor nodes, and react to changes in task and network requirements as shown in Fig. 1. Thus, energy efficiency is an important issue in sensor networks. Since routing consumes a lot of energy, an efficient routing scheme in sensor networks is also important [1]. Fig. 1. Wireless sensor network Low Energy Adaptive Clustering Hierarchy (LEACH) is a clustering-based protocol shown in Fig. 2. LEACH utilizes Manuscript received March 27, 2011; revised February 10, 2012. The authors are with the National Institute of Technology Warangal, Deemed University, Warangal, India (e-mail: venut@ nitw.ac.in; e-mail: sarma@nitw.ac.in). randomized rotation of local cluster base stations evenly distribute the energy load among the sensors in the network. It uses localized coordination to enable scalability and robustness for dynamic networks and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. In this paper, an improved LEACH protocol for data gathering and aggregation is proposed. Such innovation can extend the lifetime of the whole network due to much less energy dissipation for data transmission to base station [2]. Fig. 2. Operation of LEACH algorithm The operation of LEACH is broken up into rounds, where each round begins with a set-up phase, when the clusters are organized, followed by a steady state phase, when data transfers to the base station occur. In order to minimize overhead, the steady-state phase is long compared to the set-up phase. LEACH outperforms several static clustering algorithms by requiring nodes to volunteer to be high-energy cluster-heads and adapting the corresponding clusters based on the nodes that choose to be cluster-heads at a given time. At different times, each node has the burden of acquiring data from the nodes in the cluster, fusing the data to obtain an aggregate signal, and transmitting this aggregate signal to the base station. LEACH is completely distributed, requiring no control information from the base station, and the nodes do not require knowledge of the global network in order for the LEACH algorithm to perform. LEACH is based on the three factors: 1) Extension of network lifetime Maximizing Network Lifetime through Varying Transmission Radii with Energy Efficient Cluster Routing Algorithm in Wireless Sensor Networks T. Venu Madhav and N. V. S. N. Sarma (()) (()) (()) (()) (()) (()) (()) (()) (()) (()) Base Station Cluster-head Cluster-head Cluster-head Sensor Cluster Cluster Cluster International Journal of Information and Electronics Engineering, Vol. 2, No. 2, March 2012 205