RF Path and Absorption Loss Estimation for Underwater Wireless Sensor Networks in Different Water Environments

Abstract

Underwater Wireless Sensor Network (UWSN) communication at high frequencies is extremely challenging. The intricacies presented by the underwater environment are far more compared to the terrestrial environment. The prime reason for such intricacies are the physical characteristics of the underwater environment that have a big impact on electromagnetic (EM) signals. Acoustics signals are by far the most preferred choice for underwater wireless communication. Because high frequency signals have the luxury of large bandwidth (BW) at shorter distances, high frequency EM signals cannot penetrate and propagate deep in underwater environments. The EM properties of water tend to resist their propagation and cause severe attenuation. Accordingly, there are two questions that need to be addressed for underwater environment, first what happens when high frequency EM signals operating at 2.4 GHz are used for communication, and second which factors affect the most to high frequency EM signals. To answer these questions, we present real-time experiments conducted at 2.4 GHz in terrestrial and underwater (fresh water) environments. The obtained results helped in studying the physical characteristics (i.e., EM properties, propagation and absorption loss) of underwater environments. It is observed that high frequency EM signals can propagate in fresh water at a shallow depth only and can be considered for a specific class of applications such as water sports. Furthermore, path loss, velocity of propagation, absorption loss and the rate of signal loss in different underwater environments are also calculated and presented in order to understand why EM signals cannot propagate in sea water and oceanic water environments. An optimal solk6ution for underwater communication in terms of coverage distance, bandwidth and nature of communication is presented, along with possible underwater applications of UWSNs at 2.4 GHz.

State-of-the-art of the Physical Layer in Underwater Wireless Sensor Networks

“…Acoustic waves are the only feasible physical layer technology for underwater networks communication [12] [13]. In fact, electromagnetic waves propagate for a very short range (less than 1 meter at 1 MHz [13]) in underwater due to the high attenuation and absorption at high frequency. In seawater, the absorption of an electromagnetic signal is approximately , where f is the frequency in hertz [14].…”

“…Optical links are also not good for use in water for many reasons. First, the absorption of the optical signal in water is very high and hence can propagate only for short distances (less than 10 meters at 1 GHz [13]). Second, it suffers from scattering [15].…”

Energy‐efficient design of 3D UWSNs leveraging compressive sensing and principal component analysis: A communication techniques perspective

“…Radio wave gets severally attenuated because of conductive nature of the water medium. But as compared with other communication techniques, radio waves are less affected by ambient noise, turbidity, and temperature …”

“…But as compared with other communication techniques, radio waves are less affected by ambient noise, turbidity, and temperature. 9,10 Due to the availability of limited supply of power in the sensor node, clustering technique is generally incorporated into the wireless sensor network. 11,12 The basic idea behind the clustering is to divide the entire field of interest into small nonoverlapping segments called as clusters.…”

Characterisation of Propagation Loss for a 3G Cellular Network in a Crowded Market Area Using CCIR Model

“…Propagation loss is one of the key elements that is usually required in the planning and design of cellular networks [1][2][3][4][5][6][7]. Generally, propagation loss models are developed and used to estimate the expected propagation loss a given wireless signal at a particular frequency will experience while propagating in a given area [8][9][10][11][12][13][14].…”