A Static Multi-hop Underwater Wireless Sensor Network Using  RF Electromagnetic Communications

Abstract

Most underwater sensor networks choose acoustics as the medium for wireless transmission. However, electromagnetic waves also offer great merits for transmission in special underwater environment. A small scale wireless sensor network is deployed using electromagnetic waves with a multi-hop static topology under shallow water conditions where there is a high level of sediment and aeration in the water column. Data delivery is scheduled via daily cycles of sleeping and waking up to transmit. Due to the unique features of the network, ad-hoc on-demand Distance Vector (AODV) is chosen as the routing protocol. Modeling and simulations are conducted to evaluate network performance in terms of failure tolerance, congestion handling, and optimal grid arrangements. The results demonstrate the likely effectiveness of the designated network for this and similar scenarios.

Re-evaluation of RF electromagnetic communication in underwater sensor networks

“…Research on underwater EM communication is currently ongoing, with examples such as [13,14]. Table 1 outlines the three major underwater communication technologies in terms of benefits, limitations, and requirements.…”

Electromagnetic Waves Under Sea: Bow-Tie Antennas Design for Wi-Fi Underwater Communications

“…The speed of EM waves is higher than that of acoustic ones and mainly depends on permeability (μ), permittivity (ε), conductivity (σ) and volume charge density (ρ) [8]. These parameters change with the type of water, thus the wave propagation speed also varies.…”

“…For example, sea water has a high conductivity average value, which changes with the salinity and physical properties of each kind of sea water and is stated to be around 4 S/m [5,9]. For pure water the typical value ranges [8] between 0.005 and 0.01 S/m.…”

“…Impedance matching is very important in order to maximize the power transfer [3,8,18]. For this reason, the feed gap has been studied thoroughly for the Bow-Tie antenna design.…”

“…WSN are stationed underground or underwater, in order to monitor soil or sea properties respectively and then transmit the collected data to an access point on the surface as presented in Figure 1 [5]. Due to the high attenuation of the electromagnetic signal in water, most of the underwater wireless sensors rely on sonic transducers for wireless communication employing sound waves, and this is a proven technology [7,8]. Due to the fact that sonic transceivers use many nodes to overcome the high path losses in water, the cost is significantly high.…”