Oceanic sensor networks that collect and transmit high-quality, real-time data could transform our understanding of marine ecology, improve pollution and disaster management, and inform the multiple industries that draw on ocean resources. A KAUST research team is designing and optimizing underwater wireless sensor networks that could vastly improve existing ocean sensing equipment.

"Currently, underwater sensors use acoustic waves to communicate data," explains Nasir Saeed, who is working on a new hybrid optical-acoustic sensor design with colleagues Abdulkadir Celik, Mohamed Slim Alouini and Tareq Al-Naffouri.

"However, while acoustic communication works over long distances, it can only transmit limited amounts of data with long delays. Recent research has also shown that noise created by humans in the oceans adversely affects marine life. We need to develop alternative, energy-efficient sensors that limit noise pollution while generating high-quality data."

One option is to use optical communication technology instead, but light waves will only travel short distances underwater before they are absorbed. Optical sensors also rely heavily on pointing and tracking mechanisms to ensure they are correctly orientated to send and receive signals. The team therefore propose a hybrid sensor capable of transmitting both acoustic and optical signals simultaneously. In this way, a data-collection buoy on the water surface can communicate with every sensor in a network spread out beneath it.

However, marine research requires accurate measurements taken from precise locations, so scientists need to know where every sensor is at any given time. The team used mathematical modeling to develop a proof-of-concept localization technique.

"Using our technique, the sensors transmit their received signal strength information (RSSI) to the surface buoy," says Saeed. "For a large communication distance, the sensors use acoustic signals, but if the sensor is within close range of another sensor, it will send an optical signal instead."

Multiple RSSI measurements for each sensor are collected by the surface buoy. The buoy then weights these measurements to give preference to the most accurate readings before calculating where each sensor is positioned.

Alouini's and Al-Naffouri's teams propose that their sensors will require a new energy source rather than relying on short-term battery power. They envisage an energy-harvesting system that powers fuel cells using microscopic algae or piezoelectric (mechanical stress) energy.

Research paper

Related Links
King Abdullah University of Science and Technology
Water News - Science, Technology and Politics

Tweet

Thanks for being here; We need your help. The Space Media Network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceMediaNetwork Contributor $5 Billed Once credit card or paypal		SpaceMediaNetwork Monthly Supporter $5 Billed Monthly paypal only

Self-driving robots collect water samples to create snapshots of ocean microbes
Honolulu HI (SPX) Mar 14, 2018
For the first time, scientists from the University of Hawai'i at Manoa (UH Manoa) and the Monterey Bay Aquarium Research Institute (MBARI) will deploy a small fleet of long-range autonomous underwater vehicles (LRAUVs) that have the ability to collect and archive seawater samples automatically. These new robots will allow researchers to track and study ocean microbes in unprecedented detail. Ocean microbes produce at least fifty percent of the oxygen in our atmosphere while removing large amounts ... read more