J. ICT Res. Appl., Vol. 11, No. 1, 2017, 55-76 55 Received February 24 th , 2016, Revised December 14 th , 2016, Accepted for publication March, 6 th , 2017. Copyright © 2017 Published by ITB Journal Publisher, ISSN: 2337-5787, DOI: 10.5614/itbj.ict.res.appl.2017.11.1.4 An Energy Aware Unequal Clustering Algorithm using Fuzzy Logic for Wireless Sensor Networks Dibya Ranjan Das Adhikary* & Dheeresh Kumar Mallick Department of Computer Science and Engineering, Birla Institute of Technology, Mesra, Ranchi-835 215, India *E-mail: dibya@bitmesra.ac.in Abstract. In wireless sensor networks, clustering provides an effective way of organising the sensor nodes to achieve load balancing and increasing the lifetime of the network. Unequal clustering is an extension of common clustering that exhibits even better load balancing. Most existing approaches do not consider node density when clustering, which can pose significant problems. In this paper, a fuzzy-logic based cluster head selection approach is proposed, which considers the residual energy, centrality and density of the nodes. In addition, a fuzzy-logic based clustering range assignment approach is used, which considers the suitability and the position of the nodes in assigning the clustering range. Furthermore, a weight function is used to optimize the selection of the relay nodes. The proposed approach was compared with a number of well known approaches by simulation. The results showed that the proposed approach performs better than the other algorithms in terms of lifetime and other metrics. Keywords: clustering; energy aware clustering; fuzzy logic; unequal clustering; wireless sensor network. 1 Introduction The development of micro-electromechanical system technology, digital electronics and wireless technology has led to the development of low-cost, low-power, tiny intelligent devices called sensors, with built-in sensing, computing and communication capabilities. Sensors are of limited capability, so a group of sensors is required to sense the area of interest. These collaborative efforts of sensors form a network, which is called a wireless sensor network (WSN). The typical work of a WSN is to monitor the area of interest and report to an observer system, called the base station (BS). Thus, every sensor senses its own area, processes the gathered data and transmits the processed data to the base station. Energy is consumed while sensing, processing and transmitting. Sensors are battery-powered and in most scenarios it is not feasible to replace or recharge the batteries. Therefore energy-efficiency is a major issue in the design of WSNs.