Wireless Sensor Networks (WSNs) present new generation of real time embedded systems with limited computation, energy and memory resources that are being used in wide variety of applications where traditional networking infrastructure is practically infeasible. In recent years many approaches and techniques have been proposed for optimization of energy usage in Wireless Sensor Networks. In order to gather information more efficiently, wireless sensor networks are partitioned into clusters. However, these methods are not without problems. The most of the proposed clustering algorithms do not consider the location of the base station. This situation causes hot spots problem in multi-hop wireless sensor networks. Unequal clustering mechanisms, which are designed by considering the base station location, to some extent solve this problem. In this paper, we present issues related to these approaches.

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Wireless Sensor Networks Aggregation Fuzzy Logic Fuzzy Clustering Probabilistic Clustering Unequal Clustering