%0 Journal Article %T Link Expiration Time-Aware Routing Protocol for UWSNs %A Md. Ashraf Uddin %A Mamun-or-Rashid %J Journal of Sensors %D 2013 %I Hindawi Publishing Corporation %R 10.1155/2013/625274 %X We propose a link expiration time-aware routing protocol for UWSNs. In this protocol, a sending node forwards a data packet after being sure that the packet reaches the forwarding node, and acknowledgment is returned to the sending node after receiving the data packet. Node mobility is handled in the protocol through the calculation of the link expiration time and sending the packet based on the link expiration time. Although the protocol employs two types of control packet, it provides less energy consumption and at the same time is providing better reliability of packets reaching to the destination because of using acknowledgement packet. The forwarding decision of node is taken by applying Bayes¡¯ uncertainty theorem. We use depth, residual energy, and distance from the forwarding node to the sending node as evidence in Bayes¡¯ theorem. In this protocol, we use the concept of expert systems ranking potentially true hypothesis. Extensive simulation has been executed to endorse better performance of the proposed protocol. 1. Introduction About seventy percentage of the Earth is covered by water. This huge area is continuously being explored with a view to discover hidden knowledge and unknown resources. The research under water is being accomplished for the purpose of many kinds of application such as ocean sampling networks, environmental monitoring, undersea explorations, disaster prevention, and mine reconnaissance [1¨C3]. Underwater sensor network has appeared as a new dimension that helps in investigating the vast area under water and provides vital information to the surface. One of the imperative sections of underwater sensor network is to mature the routing protocols that are already existent and to revamp the routing protocol for UWSNs. In order to develop the routing protocol for UWSNs, some concerns pertaining to sensor networks have to be considered. UWSNs have to face some challenges such as node mobility, limited battery, limited bandwidth, and multipath noise. In UWSNs, the node moves with the velocity of 3¨C6£¿km/h [4] because of the water current. So, it is not possible to progress routing protocols which work with the whole topology. Moreover, underwater sensor node cannot be recharged or changed because of the harsh underwater environment. Underwater sensor node uses an acoustic modem whose propagation speed is 1500£¿m/s [5] to transfer data to each other. Our proposed routing protocol is devised by cogitating upon limited battery and limited bandwidth. Our proposed routing protocol provides shorter end-to-end delay and evades control %U http://www.hindawi.com/journals/js/2013/625274/