Sensor nodes are supposed to function independently for a long timespan through a restricted source of energy in Wireless sensor networks (WSNs). For prolonging the network lifespan, sensor nodes need to be energy-efficient. To split the sensing region of WSNs into clusters is a noble methodology is to lengthen network lifespan. Clustering methods rotate the extra burden of head of cluster nodes among other nodes of the network through head rotation and re-clustering techniques. Overhead cost is greater in case of Re-clustering as compared to rotation method due to its global approach. Head rotation takes place when residual energy of cluster head falls below a fixed energy threshold. However, this fixed threshold does not consider the existing load of cluster head which become foremost cause for enhancing their early death. This chapter proposes an Energy-Efficient Rotation Technique of Cluster Head (EERTCH) for WSNs, which takes existing load of cluster head in consideration for their rotation.
TopIntroduction
Wireless sensor networks (WSNs) comprise a huge number of small nodes. These nodes have sensing, computation, and wireless communications capabilities (Akyildiz et al, 2002). They are deployed in sensing area. These nodes can be deployed randomly or manually installed. Main function of these nodes is to collect the facts from the sensing area, process the collected facts, and then transmit to other nodes or to a Base Station (BS) wirelessly. BS is linked to an available communications structure or to the Internet to facilitate a customer can have access to the presented data.
WSNs have found applications in industry, house, health, security, disaster relief administration and many more. They are furthermore utilized in monitoring of inaccessible location applications (Zaheeruddin et al, 2017; Ari et al, 2015). In inaccessible situation, substituting or filling up the attached battery source of the sensor is very tough work. Main limitation of WSNs is their restricted energy resource (Aruna et al, 2012; Titouna et la, 2016). Extending lifespan of the network is sparking research issue. Consequently, researchers have recommended various methods such as duty cycling, reduction of data, and management of topology etc for increasing the lifespan of the network. Duty cycling approach allows nodes to go in sleep while they are not in usage to save their energy. The data reduction technique decreases the energy consumption through diminishing the magnitude of data produced, processed, and communicated (Willett et al, 2004). The topology management constructs and preserves a reduced set of nodes for saving their energy (Yunhuai et al, 2010; Zhang et al, 2007; Ingelrest et al, 2006). Hierarchical or cluster-based communication techniques are utmost suitable for increasing the lifespan of WSNs ((Liu et al, 2012; Aruna et al, 2018).
A cluster-based communication method splits whole network into several clusters where a node has to take responsibility of head for a particular cluster and other nodes of that cluster are become member of the cluster (Afsar et al, 2014; Heinzelman et al, 2000). Gathered information from sensor nodes sends to BS into number of rounds. Every round is comprised of two sub-stages: forming the cluster structure and transmitting the gathered data. Cluster head selection and cluster membership are main tasks involved while forming the cluster structure. Second sub-stage is associated to the communicating of gathered information to the BS. All members direct their sensed data to an associated head. After that head combined the gathered information with its own and conveys it to the BS.