EEORS: Energy Efficient Optimal Relay Selection Protocol for Underwater WSNs

Abstract

In this paper, an energy efficient optimal relay selection protocol is proposed for underwater wireless sensor networks (UWSNs). Sensor nodes are randomly deployed in a three dimensional underwater network and is partitioned into three zones based on depth. The mid zone contains the relay nodes. Nodes in the relay zone are assigned values on the bases of location and depth. Nodes residing in the center of the relay zone are assigned highest location values. These values decrease as the nodes become farther from the center. Values are also assigned to the relay nodes based on depth. The optimal relay is the one having the highest (maximum) location and depth values. If the optimal relay is within the transmission range of the source nodes in the bottom zone, they send the data packets to the optimal relay that further forwards them to the sink. Direct transmission from source to sink at the expense of more energy is accomplished when the optimal relay lies outside the transmission range of the source nodes. Nodes in the top zone send data directly to sink. Relay nodes in the mid zone send the data to sink either directly or through the optimal relay node. When the most optimal relay node dies, the second optimal node becomes the most optimal relay node. Simulation results show that the proposed scheme outperforms the counterpart scheme in terms of energy efficiency due to the selection of the optimal relay.