Clustering and load balancing in hybrid sensor networks with mobile cluster heads

Abstract

In this paper, we consider the problem of positioning mobile cluster heads and balancing traffic load in a hybrid sensor network, which consists of two types of nodes: basic static sensor nodes and mobile cluster heads. In such a network, sensor nodes are organized into clusters and form the lower layer of the network. At the higher layer, cluster heads collect sensing data from sensors and forward data to outside observers. Such two-layer hybrid networks are more scalable and energy-efficient than homogeneous sensor networks. We show that the locations of cluster head-s can affect network lifetime significantly. The problem of maximizing network lifetime through dynamically positioning cluster heads in the network (referred to as the CHL problem in this paper) turns out to be NP-hard. We present a heuristic algorithm for positioning cluster heads and balancing traffic load in the network. We show that by moving the cluster head to a better location, the traffic load can be balanced and network lifetime can be prolonged. We conducted simulations on the NS-2 simulator, and the result-s show that our clustering algorithm can increase network lifetime by up to 35% after only three rounds of adjustments, compared to the optimal lifetime of the initial network layout.