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Technological advances in the fields of microelectronics and wireless communications have helped design and manufacture of miniaturized autonomous and reliable components, called sensors. These electronic components are capable to sense physical or environmental phenomena such as temperature level, pressure condition, humidity, etc. Indeed, sensors classified as embedded systems are deployed on a large geographical area to form a Wireless Sensor Network (WSN), that is able to collect information on defined events, and delivering them using wireless links either directly or through intermediate nodes to a particular node of treatment, called Sink or Base Station (BS). The BS provides connection to wired world where data can be collected, processed and analyzed to make decisions (Kole, Vhatkar, & Bag, 2014).
However, a sensor is very small equipment including very limited resources in terms of memory and computing, and powered with low power batteries. The sensors use their energy reserve for the purpose of calculation and data transmission.
In WSNs, every node acts as transmitter and router. The failure of sensors energy can significantly change the network topology and impose a costly reorganization of the latter. The lifetime of a sensor essentially depends on that of its battery. So, designing protocols for WSNs is influenced by a factor that is reducing energy consumption without loss of efficiency.
Hierarchical cluster-based routing protocols are considered as one of the most efficient routing protocols in WSNs due to their higher energy efficiency, network scalability, and lower data retransmission. Hierarchical routing rebuilt the network by creating a logical hierarchy of nodes for a better distribution of tasks.
Low Energy Adaptive Clustering Hierarchy (LEACH) (Heinzelman, Chandrakasan, & Balakrishnan, 2000) is one of the most popular and commonly used hierarchical routing protocols designed for this purpose. To be energy efficient, the protocol applies cluster organization on the network. It divides the network into several clusters. Each cluster is composed by a cluster head (CH) node that is used for data aggregation and transmission, and other non-CH nodes used for data sensing (Sabri & Al-Shqeerat, 2014).
The drawback to LEACH is that the number of CH nodes is little ambiguous to count. To solve this problem LEACH-C (LEACH-Centralized) (Heinzelman, Chandrakasan, & Balakrishnan, 2002) has been proposed. LEACH-C is a centralized clustering algorithm, where each node sends the information about its current location and its level of energy to the BS that utilizes this global information of the network and constructs the better clusters that use only the less energy for data transmission.
LEACH and LEACH-C experience the problem of spending huge energy in the sensor nodes because of forming repeated clusters for every fixed time interval. LEACH-F (Fixed-LEACH) (Heinzelman, 2000; Heinzelman et al., 2002) solved the repeated clustering formation by constructing fixed clusters only once using the LEACH-C set-up phase, but it would not be practical in any sort of dynamic system; the fixed nature of this protocol does not allow new nodes to be added to the system and does not adjust the system behavior based on nodes dying (Madheswaran, & Shanmugasundaram, 2013).
In this paper, we present a new routing scheme for dynamic WSNs that we have called Two Rounds Based LEACH (TR-LEACH). Our proposed scheme inherits the characteristics of LEACH and LEACH-F, and defines a new way to manage cluster forming and CH selection. In the goal of extending the network lifetime and effective management of energy consumption, we propose a scheme that is based on reducing transmissions due to repeated clustering formation, allowing new nodes to be added to the system and adjusting the system behavior based on nodes dying. We perform extensive simulations in NS2 simulator to verify the efficiency of our new scheme face to LEACH and LEACH-C schemes in WSNs.
The rest of the paper proceeds as follows: Section 2 presents details of LEACH, LEACH-C and LEACH-F protocols. The motivation of proposing a new routing scheme for WSNs is described in section 3. Section 4 presents the proposed TR-LEACH scheme. Section 5 presents simulation experiments along with performance comparison among existing schemes and proposed scheme. Finally, some concluding remarks are given in section 6.