Adaptive Clustering—An Optimal Solution to Hotspot Issue in Wireless Sensor Networks

Abstract

In wireless sensor networks, maximization of lifetime is an important task. Load balancing with clustering is an energy efficient approach for prolonging the network lifetime. Clustering improves the energy efficiency of the network to a greater extend, but it gives rise to the energy hole or hotspot problem in wireless sensor networks. Hotspot problem is characterized by creation of an energy hole or network deadlock near to the base station. In multi-hop clustering with uniform or fixed cluster size, the cluster heads (CH’s) close to the base station gets depleted of energy much quicker than those which are at an appreciable distance, due to the increased load from data forwarding. An alternate approach to mitigate such problem is to employee adaptive or unequal clustering that involves formation of clusters with variable size. The cluster size is a function of multiple factors like remaining energy of sensor node, distance from the base station and location of the node. In adaptive clustering, the cluster size keeps decreasing while moving towards the base station in order to reduce the number of neighbors and increase the number of available cluster heads near to the base station to share the network traffic. The paper provides a detailed literature on various aspects of adaptive clustering. A comparative analysis based on taxonomy of adaptive clustering protocols is carried. The analysis indicates that adaptive clustering improves not only the energy efficiency but also the stability of the network along with other quality of service parameters.