Energy-Aware Hierarchical Topology Control for Wireless Sensor Networks

Abstract

Simple wireless sensor networks (WSNs) usually have a flat topology and transmit data using a flooding scheme of which there are several variants. However, these can cause the broadcast storming problem, reducing the efficiency and reliability of the WSN. Due to these problems, most WSNs have a cluster or tree structure

but this causes an imbalance of residual energy between nodes, which gets worse over time as nodes become defunct and replacements are inserted. Moreover, a defunct cluster head leads to a sharp drop of network connectivity. Therefore, an efficient way to improve the energy imbalance and the network connectivity is needed.

In this thesis, we propose a hierarchical topology control scheme, in which each node periodically selects its own layer accommodating itself with different levels of residual energy and the amount of data to transfer, in order to balance the energy level and to increase the network connectivity. Simulations show that this scheme can balance node energy levels, and thus extend network lifetime.

We also introduce a hierarchical topology control scheme for WSNs, which contains both energy-harvesting nodes and battery-powered nodes, in order to extend the lifetime of battery-powered nodes and to increase the network connectivity. In such a WSN, the energy harvesting nodes are also arranged in layers like the battery-powered nodes depending on their expected level of residual energy. This scheme is shown to increase the lifetime of battery-powered nodes preferentially by locating energy-harvesting nodes on the higher layers.