I. Introduction
A WSN consists of a large number of small, low power and cheap sensor nodes, used to monitor a variety of physical, military, and industrial applications. Data is collected by sensors from field, processed, and sent to the Base Station Node (BSN) according to various routing algorithm strategies [1]. BSN has improved memory and computing ability compared to normal sensor-node, enables it to perform complex processing and classification procedures before sending data to the supervisory party via communication network [2]. There are many challenges related to WSN such as communication limited range, short network lifetime, and security issues [3]. Transmitting data from field to the BSN using routing algorithm, presents the most critical operation in term of communication and energy consuming affecting WSN performances and lifetime [4]. These routing algorithms can be classified depending on the objectives, operation and the structure of the network. A Hierarchical routing algorithm that is one of the network structure classification and the most efficient routing algorithm among them [5]. It aims to reduce the consumed energy by performing multi-hop communication between the sensors and the BSN inside a prespecified cluster to minimize transmitted load through data fusion [6]. Clustering is classified into two strategies, dynamic and static. The dynamic clustering is characterized by an updated formation in every round whereas the static clustering keeps the same formation throughout network lifetime [7].