Unequal clustering in wireless sensor network: a review

<p><span>In recent time, the applications' diversity of wireless sensor network (WSN) attracts many researchers. WSN comprises of many sensor nodes with limited battery power. Therefore, energy consumption should be controlled to the optimum. Clustering is an efficient solution for energy management in WSN, but clustering does not consider the sink node location. It will cause the energy hole problem in multi-hop routing. Energy hole problem was solved by unequal clustering. A review of various unequal clustering mechanisms is presented in this paper. The comparison between the various mechanisms was based on cluster head election process, cluster properties, simulation parameters and energy efficiency to highlight a more efficient and scalable unequal clustering algorithm for </span>WSN.</p>

Minimizing the Energy Hole Problem in Wireless Sensor Networks: A Wedge Merging Approach

The Energy hole problem, a common phenomenon in wireless sensor networks, significantly decreases the lifetime of any deployed network. Some of the popular techniques to minimize such problems are using mobile sinks instead of static sinks, extending the transmission range dynamically, and deploying redundant sensor nodes near the base station/sink. The major drawback to these techniques are that energy holes may still be created at some point due to their static nature of deployment, despite having the overall residual energy very high. In this research work, we adopt a new approach by dividing the whole network into equiangular wedges and merging a wedge with its neighboring wedge dynamically whenever individual residual energy of all member nodes of a wedge fall below a threshold value. We also propose an efficient Head Node (HN) selection scheme to reduce the transmission energy needed for forwarding data packets among Head Nodes. Simulation results show that WEMER, our proposed WEdge MERging based scheme, provides significantly higher lifetime and better energy efficiency compared to state-of-the-art Power-Efficient Gathering in Sensor Information Systems (PEGASIS) and contemporary Concentric Clustering Scheme (CCS), and Multilayer Cluster Designing Algorithm (MCDA).

Energy-Efficient Mobility Heuristics for Maximizing Network Lifetime in Robotic Wireless Sensor Networks

In a static wireless sensor networks (WSN), the fundamental issue is the formation of energy hole in the sink's immediate locality. The solution to the energy-hole problem can be resolved by incorporating mobile entities like mobile robot (MR) into the network. This chapter proposes three strategies that exploits the mobility of the MR to overcome the energy-hole problem resulting in optimized energy usage across the network and thus maximized network lifetime. Firstly, the energy hole problem using MR is formulated as an optimization model to maximize the sojourn time of the MR at each node and a MR-ranking heuristic that ranks the critical node to be serviced is proposed. Secondly, MR-optimal scheme that finds the optimal path for the MR is formulated and designed. Thirdly, Multi-MR cooperation approach is proposed where multiple MR's collaborate to service the critical nodes. Adequate experiments have been performed to analyze the performance of the proposed schemes. The proposed methods ensure uniform energy distribution and prolonged network lifetime.