Abstract: A wireless sensor network (WSN) is a collection of nodes organized into a cooperative network, which are small energy constrained devices The efficient use of energy source in a sensor node is most desirable criteria for prolong the life time of wireless sensor network. In WSN, sensors near the static sink have to relay the data of the nodes away from the sink and as a result they drain their energy very quickly. It result in network partitioning and can significantly limit the network lifetime, problem is termed as hotspot problem. So designing efficient routing for reducing energy consumption is the important factor. Recently, mobile sink approach has been used to address the hotspot problem but it increase end to end delay which is not acceptable for delay sensitive application. In this paper, to solve the above problem the consumption of energy during the transmission of data from sensor nodes to the sink has been calculated. Routing protocols in WSNs along with the most energy efficient protocol named LEACH ( low energy adaptive clustering hierarchy) and AODV protocol is used. the proposed protocol incurs less end to end delay and is energy efficient. Intensive Simulations are carried out to evaluate the performance of the proposed strategy.

Keywords: Wireless sensor network, clustering, energy efficiency, data gathering, mobile sink, static sink, LEACH, Shortest path routing.