Wireless sensor network (WSN) is one of the most popular areas of research due to the constant improvement in the field of wireless technology and embedded system. Now, WSNs are extensively deployed in every area such as industry, civilian and military applications. These applications include monitoring, tracking, event detection and disaster management. The long term usefulness of WSN mainly relies on the lifetime of sensor nodes. The lifetime of SN mainly depends on its battery source. Since these batteries can be hardly replaceable, the improvement in the lifetime of WSNs can be achieved through the conservation of battery energy. In order to achieve this purpose, it is very important to design an energy-efficient routing protocol for efficient use of the limited energy of WSNs.
Many researchers applied the concept for clustering of sensor nodes and efficient routing to conserve the energy of sensor nodes and these techniques significantly improved the lifetime of WSN. LEACH (Low Energy Adaptive Clustering Hierarchy), the first adaptive hierarchical clustering routing protocol that considers energy saving, comprises two phases i.e. setup phase and steady phase.
But LEACH protocol has some critical drawbacks: It does not consider residual energy of a node, so a node with low energy can be selected as a cluster head. Also, due to randomized election of cluster heads, it is possible that elected cluster heads very close to each other might cause congestion in particular areas.
To solve the critical problem due to residual energy in LEACH, some protocols similar to LEACH, but considering residual energy of nodes were introduced. Nevertheless, LEACH based protocols considering residual energy of nodes can never deal with irregular election of cluster heads.
In response to the above issue, Kim Chol Man, a researcher at the Faculty of Information Science and Technology, has presented an improved cluster head election algorithm using residual energy and network address of nodes.
This algorithm is based on LEACH and considers both remaining energy and network address of nodes to revise the cluster head threshold equation. He assigned the network addresses of nodes by distributed address assignment mechanism (DAAM) of ZigBee. As he used the network address of a node in the threshold equation, the cluster type created in a new round is similar to the old cluster type. In addition, he dynamically changed the upper limit of the interval that generates random numbers to optimize the number of cluster heads.
He evaluated the performance of the proposed LEACH-NA using network Simulation platform NS-2. The simulation results demonstrate that the proposed algorithm shows better performance than the existing ones in terms of network lifetime and energy conservation, and the number of cluster heads in every round is more stable than other algorithms based on LEACH.
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