Improved Energy and Communication for Underwater Wireless Sensor Network Based Location Estimation

The area of underwater wireless sensor networks (UWSNs) is garnering an increasing attention from researchers due to its broad potential for exploring and harnessing oceanic sources of interest. Because of the need for real-time remote data monitoring, underwater acoustic sensor networks (UASNs) have become a popular choice. The restricted availability and nonrechargeability of energy resources, as well as the relative inaccessibility of deployed sensor nodes for energy replenishment, forced the development of many energy optimization approaches un the UASN. Clustering is an example of a technology that improves system scalability while also lowering energy consumption. Due to the unstable underwater environment, coverage and connectivity are two important features that determine the proper detection and communication of events of interest in UWSN. A sensor network consists of several nodes that are low in cost and have a battery with low capacity. In wireless sensor networks, knowing the position of a specific device in the network is a critical challenge. Many wireless systems require location information from mobile nodes. Keywords: MAC, Communication cost, IDV-Hop algorithm, Localization, Ranging error, unconstrained optimization, Wireless sensor network, Distributed Least Square

Symmetric Connectivity of Underwater Acoustic Sensor Networks Based on Multi-Modal Directional Transducer

Topology control is one of the most essential technologies in wireless sensor networks (WSNs); it constructs networks with certain characteristics through the usage of some approaches, such as power control and channel assignment, thereby reducing the inter-nodes interference and the energy consumption of the network. It is closely related to the efficiency of upper layer protocols, especially MAC and routing protocols, which are the same as underwater acoustic sensor networks (UASNs). Directional antenna technology (directional transducer in UASNs) has great advantages in minimizing interference and conserving energy by restraining the beamforming range. It enables nodes to communicate with only intended neighbors; nevertheless, additional problems emerge, such as how to guarantee the connectivity of the network. This paper focuses on the connectivity problem of UASNs equipped with tri-modal directional transducers, where the orientation of a transducer is stabilized after the network is set up. To efficiently minimize the total network energy consumption under constraint of connectivity, the problem is formulated to a minimum network cost transducer orientation (MNCTO) problem and is provided a reduction from the Hamiltonian path problem in hexagonal grid graphs (HPHGG), which is proved to be NP-complete. Furthermore, a heuristic greedy algorithm is proposed for MNCTO. The simulation evaluation results in a contrast with its omni-mode peer, showing that the proposed algorithm greatly reduces the network energy consumption by up to nearly half on the premise of satisfying connectivity.