Challenges and vision of wireless optical and acoustic communication in underwater environment

Abstract

Summary Underwater Wireless Communication is a rapidly growing technology in the research domain. The researchers have been working towards the developments in underwater communication by investigating climatic changes, prediction of natural disasters, marine environment, monitoring aquatic life, oceanographic transmission, and data collection. The main objective of underwater communication is to achieve lossless, high transmission with the least power consumption. The Unmanned Underwater Vehicles (UUVs) and Autonomous Underwater Vehicles (AUVs) are set up with remote instruments and sensors to enable the natural exploration of the resources in the undersea environment. This research article is based on the study of various modes of communication, architectures, and protocol layers involved in underwater communication. Furthermore, an underwater hybrid connection is established by opto‐acoustic signals, and the overview of various performance characteristics, channel behaviors, and issues in the underwater scenario are investigated.

A Review–Unguided Optical Communications: Developments, Technology Evolution, and Challenges

“…Photoacoustic impact, also known as optoacoustic impact, is a more effective technique to transform light energy into ultrasonic radiation at the air-water interface [215]. In practice, there are mainly three methods [216] for achieving the optoacoustic effect for the conversion of light waves into acoustic waves, namely (i) direct optical beam focusing, (ii) optical beam focusing on the active relay, and (iii) optical beam focusing on the passive relay [209]. In the direct beam focusing method, the transmission optics shape either a high-power continuous wave (CW) or a pulsed wave (PW) optical beam and pass it to the desired point on the water surface.…”

“…The wide-band free-space transmission optics decides the laser beam parameters such as beam divergence (θ), beam diameter on the water surface (D), beam source diameter (d), beam footprint area, footprint geometry, incident angle (ϕ), optical wavefront profile, collimation/focus level, beam polarization, etc., and transmits it to the point of interest on the water surface. Instead of a Gaussian optical beam, an oblique beam can also be used since it gives a considerable increment in the in-air to in-water range [211,216]. Based on the principle of an acoustic signal traveling inside a water medium, the opto-acoustic energy conversion mechanism is classified into linear and non-linear energy dispersion [217].…”

An Overview of Key SLAM Technologies for Underwater Scenes

“…To obtain reliable estimates, SLAM for underwater scenes typically requires the use of specialized sensors such as inertial measurement units (IMU), Doppler velocity log (DVL), and depth sensors [37]. Acoustic and laser sensors are also widely used for sensing the underwater environment [38,39]. The fusion of different sensors has become an important approach in solving underwater SLAM.…”

Optimized deep learning driven signal detection and adaptive channel estimation in underwater acoustic IoT networks

“…1,2 It can be difficult to obtain accurate estimates and reliable equalizations of the time-varying multipath channels when there is relative motion between the transmitter and the receiver since the channels can shift significantly. 3,4 Using acoustic communication technology, underwater communication can achieve extended communication lengths ranging from a few meters (m) to tens of kilometers (km) for low and high transmission frequencies. 5 Acoustic communication is a widely used physical layer technology.…”

“…However, the UWAC channels are hostile due to the influence of surface waves, ocean currents, turbulence, etc., on the multipath interference, which can be severe and time‐varying 1,2 . It can be difficult to obtain accurate estimates and reliable equalizations of the time‐varying multipath channels when there is relative motion between the transmitter and the receiver since the channels can shift significantly 3,4 . Using acoustic communication technology, underwater communication can achieve extended communication lengths ranging from a few meters (m) to tens of kilometers (km) for low and high transmission frequencies 5 .…”