Energy-efficient algorithms for ad hoc wireless sensor networks

Abstract

The interest in ad hoc Wireless Sensor Networks (WSN) has been growing rapidly in the past few years due to its wide range of applications in Environment Monitoring and Forecasting, Health and Medical Care, Underwater Communications, Smart Energy, and Building and Home Automation industries. The performance of different network protocols, as well as their sensitivity and the effect of different network parameters, needs to be studied and evaluated for the implementation of WSN with the right protocols and optimal parameters. With the increasing deployment of unmanned and energy-constrained sensor devices in large-scale wireless sensor networks, energy efficiency and network lifetime have become key considerations in designing WSN routing protocols. In this work, we propose a fully distributed, multi-path load-balancing routing protocol based on Dynamic Source Routing (DSR) to improve network lifetime performance. The new protocol is simulated in ns-2 and compared with the commonly used Destination- Sequenced Distance Vector (DSDV), Ad hoc On-Demand Distance Vector (AODV) and DSR protocols. The simulation results show that the new routing protocol improves network lifetime significantly without sacrificing packet delivery performance. Another major source of energy wastage is the idle listening of sensor nodes in the MAC layer. Different variants of synchronous duty-cycle MAC protocols have been designed for WSNs to reduce MAC layer energy consumption. However, the synchronisation process of theses protocols remains a significant contributor to the energy consumption. Energy consumption models of duty-cycle MAC protocols in single-hop neighbourhoods are first developed and analysed. A new synchronisation algorithm, 1-Sync, is proposed to address the high energy consumption problem of the existing fixed periodic synchronisation (F-Sync) algorithm, and the Intelligent Network Synchronisation (INS) algorithm. The analysis and simulation results have shown that the proposed 1-Sync algorithm yields better energy performance than the F-Sync and INS algorithms in both low and high density neighbourhoods. ii In large multi-neighbourhood networks, the above synchronisation algorithms are inadequate in handling high density, high drift, and low duty-cycle operations. An adaptive energy-efficient synchronisation algorithm referred to as C-Sync, is proposed. C-Sync reduces energy consumption by adaptively regulating the synchronisation traffic and the wakeup period based on the changing network neighbourhood conditions through counter-based and exponential-smoothing algorithms. Extensive simulations of multi-hop multi-neighbourhood network scenarios are performed using ns-2; the simulation results have shown that C-Sync outperforms F-Sync and 1-Sync in energy efficiency, packet delivery ratio, and end-to-end packet delay over a wide range of node densities, drift rates and duty cycles.