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Academic Editor:Jiun-Long Huang
Department of Communication Technology and Network, Faculty of Computer Science and Information Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia
Received 13 February 2014; Revised 12 May 2014; Accepted 20 May 2014; 3 July 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Wireless sensor networks (WSNs) consist of a hundred to a thousand sensor nodes, which measure a property from the environment as well as processing and transmitting the collected data to the base station (BS) [1]. However, they have many constraints, because the sensor nodes have limited capabilities. Since the energy resources of the sensor nodes are limited and nonrechargeable, energy efficiency is a very critical issue in the design of the network topology, which affects the network lifetime significantly. Hence, the main concern in designing protocols is how to reduce the energy consumption and extend the network lifetime [2].
It has been proved by many researchers that among different categories of routing protocols based on the network architecture, cluster-based (hierarchical) routing protocols are more energy efficient and increase the scalability as well as lifetime of the network [3-5]. Clustering schemes divide the field into multiple clusters, where each cluster is controlled by a cluster head (CH) with the purpose of gathering data from cluster members (CM). CHs act as the local BS for their own clusters. After gathering data and performing data aggregation to omit the redundant data, the data are transmitted to the BS [6-8].
Networks with nonuniform node distribution make the cluster-based routing protocols less efficient [9, 10]. The nonuniform node deployment makes the energy consumption of the nodes more imbalanced [9]. Furthermore, as the density of the sensor nodes varies in each region due to nonuniform node distribution, in dense area the sensed and transmitted data are extremely correlated and redundant. In random and nonuniform node distribution, there may exist some redundant sensor nodes whose coverage areas are completely covered by their neighbor nodes. These redundant sensor nodes can be identified and scheduled to be activated alternatively in order to prolong the network lifetime [11].
Energy...