Improving on HEED protocol of wireless sensor networks with sleep scheduling algorithm

Wireless Sensor Networks together hundreds or thousands of sensors allow users to monitor a remote areas. Improving energy efficiency while ensuring a certain coverage ratio in Wireless Sensor Networks (WSNs) is an extremely challenging issue. In some long-term monitoring applications of WSNs, where full coverage is not required, nodes can go to sleep mode to reduce energy consumption and increase network lifetime. In this paper, we propose three sleep scheduling algorithms based on HEED (Hybrid Energy-Efficient Distributed clustering) algorithm: Fixed Node Degree (FND) algorithm, Dynamic Node Degree (DND) algorithm and Dynamic Node Degree combined with Remaining Energy (DNDRE) algorithm. Our primary goal is to maximize the network lifetime while guaranteeing coverage ratio of the entire WSNs. Furthermore, we propose a simple and practical coverage ratio calculation method. We find the DNDRE performs the best in three sleep scheduling algorithms.