An energy efficient routing using multi-hop intra clustering technique in WSNs

One of the major concern of Wireless Sensor Networks (WSNs) is to minimize the energy consumption of the sensor nodes. In multi-hop clustering, sensor nodes closer to the Base Station (BS) deplete their energy faster as compared to far away nodes. Transmission of own data as well as other nodes data by the nearer nodes is the prime cause for this uneven energy consumption. Hence, the nodes closer to the BS die quickly and network gets disconnected, though most of the nodes have adequate energy to communicate. This type of problem is known as hot spot problem in WSN. In this paper, we propose a multi-hop intra-cluster technique in uneven clustering, to minimizing the hot spot and intra-cluster communication problems. The BS divides the whole network into three types of unequal fixed square shaped Grids (clusters). In each cluster, the BS selects a Cluster Head (CH) based on number of hop or neighbour nodes and residual energy of the sensor nodes. Our proposed scheme uses both (centralized and distributed) methods for efficient routing in the network. Formation of all clusters and CH selection are performed centrally, whereas intra and inter-cluster communications are handled in a distributed manner. Here, uneven clusters help to minimize the hot spot problem in WSNs. In order to reduce the intra-cluster routing, we limit the forwarding packets maximum up to two hop in medium size and three hop in large size clusters. The BS checks residual energy of CH and its one hop child nodes after completion of every round. If either CH or one hop neighbours' residual energy is less than or equal to p fraction energy of the total energy, the BS station starts new CH selection process. By keeping intra-cluster communication distance minimum and avoiding rotation of CH in every round, this scheme saves significant amount of energy in WSN. The result obtained through simulation proves the superiority of our protocol in terms of residual energy, number of active nodes and network lifetime as compared to the existing protocols. Though, our protocol sustains upto more than 1000 rounds, proved that it has less hot spot as compared to other existing protocols.