44 research outputs found
Re-Evaluation of RF Electromagnetic Communication in Underwater Sensor Networks
Most underwater wireless networks use acoustic
waves as the transmission medium nowadays,
but the chances of getting much more out of
acoustic modems are quite remote. Optical links
are impractical for many underwater applications.
Given modern operational requirements
and digital communications technology, the time
is now ripe for re-evaluating the role of electromagnetic
signals in underwater environments.
The research presented in this article is motivated
by the limitations of current and established
wireless underwater techniques, as well as the
potential that electromagnetic waves can offer to
underwater applications. A case study is presented
that uses electromagnetic technology in a
small-scale underwater wireless sensor network.
The results demonstrate the likely effectiveness
of the designated network
A Comparative Assessment of Floating and Submerged Sensor Network Deployments for Monitoring Underwater Sediment Transport Processes
Wireless Sensor Networks (WSNs) are a pioneering technology in many environmental monitoring applications owing to their ability to be deployed for long periods of time in locations that cannot be reached manually. One such use-case is the monitoring of underwater sediment transport, a process that plays a significant role in coastal erosion. Previous examples of WSNs deployed for
this purpose have been in the form of underwater sensor networks (UWSNs), which have a number of shortcomings from both a practical and technical viewpoint. As such, this paper provides a comparative assessment of UWSNs and an alternative deployment approach of floating echosounding sensor networks for the purpose of monitoring underwater sediment transport
Underwater Wireless Communications in Freshwater at 2.4 GHz
Publisher copyright and source must be acknowledged with citationThere are few equations for underwater communications
in the related literature. They show that the speed propagation
and absorption coefficient in freshwater are independent
of the working frequency of the transmitted signals. However,
some studies demonstrate that electromagnetic waves present
lower losses when they are working at certain frequencies. In
this paper, we perform a set of measurements of electromagnetic
(EM) waves at 2.4 GHz in the underwater environment. In our
study case, we fix the water conditions and we measure the
behavior of EM as a function of several network parameters such
as the working frequency, data transfer rates and modulations.
Our results will show that higher frequencies do not mean worse
network performance. We will also compare our conclusion with
some statements extracted from other works.This work has been partially supported by the Ministerio de Ciencia e Innovacion, through the Plan Nacional de I+D+i 2008 - 2011 in the Subprograma de Proyectos de Investigacion Fundamental, project TEC2011 - 27516, and by the Polytechnic University of Valencia, through the PAID-05-12 multidisciplinary projects, Ref: SP20120420. This work has also been partially supported by the Instituto de Telecomunicacoes, Next Generation Networks and Applications Group (NetGNA), Portugal, and by National Funding from the FCT Fundacao para a Ciencia e a Tecnologia through the PEst - OE/EEI/LA0008/2013 Project.Sendra Compte, S.; Lloret, J.; Rodrigues, JJPC.; Aguiar, JM. (2013). Underwater Wireless Communications in Freshwater at 2.4 GHz. IEEE Communications Letters. 17(9):1794-1797. https://doi.org/10.1109/LCOMM.2013.072313.131214S1794179717
Performance of electromagnetic communication in underwater wireless sensor networks
Underwater wireless sensor networks (WSNs) composed of a number of sensor nodes that are deployed to conduct a collaborative monitoring task. Wireless signals are used for communication between the sensor nodes. Acoustic signals are the dominant signals used as a wireless communication medium in underwater WSNs due to the relatively low absorption in the underwater environments. Acoustic signals face a lot of challenges such as ambient noise, manmade noise, limited bandwidth, multipath and low propagation speed. Some of these challenges become more severe in shallow water environment where a high level of ambient and mankind noise, turbidity and multipath propagation are available. Therefore, electromagnetic signals can be applied as an alternative communication signal for underwater WSNs in the shallow water. In this project, the performance of EM communication in underwater WSNs is investigated for the shallow water environment. Theoretical calculations and practical experiments are conducted in fresh and seawater. It is shown that signals propagate for longer ranges in freshwater comparing to seawater. Theoretical results show that attenuation of electromagnetic communication in seawater is much higher than in fresh water. The attenuation is increasing with the increasing of frequency. In addition, velocity of the signal is increasing as the frequency is increasing while loss tangent is decreasing as the frequency increasing. Based on practical experiments, freshwater medium permits short ranges EM communication that does not exceed 25.1 cm for 2.4 GHz frequency. On the other hand, communication in seawater is very difficult to achieve for the same high frequency. Path loss exponent was estimated for freshwater environment based on logdistance path loss model. The estimation was achieved through a comparison between theoretical calculations and practical measurements. The path loss exponent for EM communication in fresh water was estimated to be in the range of 2.3 to 2.4
Measuring the underwater received power behavior for 433 mhz radio frequency based on different distance and depth for the development of an underwater wireless sensor network
Underwater wireless sensor network (UWSN) important to enhance the widely use of the application of the Internet of things (IoT) for underwater. Uses of the acoustics base of wave propagations are the best ways to establish the UWSN. But the unpracticality of the hardware due to the size and cost has limited the application of UWSN. Radio frequency (RF) wave propagation is the best way to overcome this situation. Low frequency of the RF wave is proven feasible and suitable for underwater communication. 433 MHz RF were chosen to measuring the underwater received power behavior between the transmitter node and receiver node based on different distance and depth. HC12 transceiver module was used as a transmitter and spectrum analyzer with the telescopic antenna was used as a receiver. The received power give a good reading when the transmitter note was at 0.5-meter depth with a maximum operating range within 12 meters from the receiver