Underwater Wireless Linear Sensor Networks (UW-LSNs
Keywords: scalability, heterogeneity, nodes deployment algorithm, underwater pipeline monitoringCopyright © 2016 Universitas Ahmad Dahlan. All rights reserved.
IntroductionUnderwater environments do not remain feasible for human operators due to the harsh underwater activities, high water pressure, hazardous underwater creatures, vast areas for exploration and lack of high frequency signals propagation [1]. Due to the underwater acoustic communication, the signal propagation speed is decreased to the speed of sound. Although in underwater, sound waves travel longer and faster than the air but still they are five times slower than the electromagnetic waves [2]. Most of deployment algorithms and routing protocols do not remain suitable for such environments as they necessitate random nodes deployment, joint topology, 2D area, higher data rate, and outcomes in large end-to-end delays [3]. Although significant areas of improvement are highly required to be there in UW-LSN monitoring techniques like scalable nodes deployment, distribution of large network, minimization of the delay in communication and efficient data deliveries to the sink; but the available data rates for the long range underwater applications is very low and not feasible for the real time communication. In short, it seems to be hard to increase the data rate for the long range underwater communication where scalable and efficient nodes deployments in distributed topology are highly supportive in this regard.In fact, UW-LSNs and terrestrial sensor networks have many common properties including deployment of large number of nodes and energy constraints; but UW-LSN stays unique in many aspects from the terrestrial sensor networks [4]. Firstly, most of the times homogenous types of sensor nodes are deployed randomly that are not scalable for extension of underwater pipelines monitoring coverage. Secondly, UW-LSN requires special deployment algorithms that assign proper nodes positions in 3D dynamic underwater environment. Thirdly, sensors are linearly deployed to maintain the linear topology and distributed topology network [5] that divides the pipeline length into sub-zones and ranges of heterogeneous sensors.