998 research outputs found
Classification of Routing Algorithms in Volatile Environment of Underwater Wireless Sensor Networks
The planet earth is basically a planet of water with less than 30% land mass available for humans to live on. However, the areas covered with water are important to mankind for the various resources which have been proven to be valuable. Such resources are gas, oil, marine products which can be used as food, and other minerals. In view of the vast area in which these resources can be found, a network of sensors is necessary so that they can be explored. However, sensor networks may not be helpful in the exploration of these resources if they do not have a sufficiently good routing mechanism. Over the past few decades, several methods for routing have been suggested to address the volatile environment in underwater communications. These continue researches; have enhanced the performance along with time. Meanwhile, there are still challenges to deal with for a better and efficient routing of data packets. Large end-to-end delays, high error channel rates, limited bandwidth, and the consumption of energy in sensor network are some such challenges. A comprehensive survey of the various routing methods for the partially connected underwater communication environment are presented in this paper
Energy Efficiency in Communications and Networks
The topic of "Energy Efficiency in Communications and Networks" attracts growing attention due to economical and environmental reasons. The amount of power consumed by information and communication technologies (ICT) is rapidly increasing, as well as the energy bill of service providers. According to a number of studies, ICT alone is responsible for a percentage which varies from 2% to 10% of the world power consumption. Thus, driving rising cost and sustainability concerns about the energy footprint of the IT infrastructure. Energy-efficiency is an aspect that until recently was only considered for battery driven devices. Today we see energy-efficiency becoming a pervasive issue that will need to be considered in all technology areas from device technology to systems management. This book is seeking to provide a compilation of novel research contributions on hardware design, architectures, protocols and algorithms that will improve the energy efficiency of communication devices and networks and lead to a more energy proportional technology infrastructure
EFFICIENT DYNAMIC ADDRESSING BASED ROUTING FOR UNDERWATER WIRELESS SENSOR NETWORKS
This thesis presents a study about the problem of data gathering in the inhospitable
underwater environment. Besides long propagation delays and high error probability,
continuous node movement also makes it difficult to manage the routing information
during the process of data forwarding. In order to overcome the problem of large
propagation delays and unreliable link quality, many algorithms have been proposed
and some of them provide good solutions for these issues, yet continuous node
movements still need attention. Considering the node mobility as a challenging task,
a distributed routing scheme called Hop-by-Hop Dynamic Addressing Based (H2-
DAB) routing protocol is proposed where every node in the network will be assigned
a routable address quickly and efficiently without any explicit configuration or any
dimensional location information. According to our best knowledge, H2-DAB is first
addressing based routing approach for underwater wireless sensor networks
(UWSNs) and not only has it helped to choose the routing path faster but also
efficiently enables a recovery procedure in case of smooth forwarding failure. The
proposed scheme provides an option where nodes is able to communicate without
any centralized infrastructure, and a mechanism furthermore is available where
nodes can come and leave the network without having any serious effect on the rest
of the network. Moreover, another serious issue in UWSNs is that acoustic links are
subject to high transmission power with high channel impairments that result in
higher error rates and temporary path losses, which accordingly restrict the
efficiency of these networks. The limited resources have made it difficult to design a
protocol which is capable of maximizing the reliability of these networks. For this
purpose, a Two-Hop Acknowledgement (2H-ACK) reliability model where two
copies of the same data packet are maintained in the network without extra burden
on the available resources is proposed. Simulation results show that H2-DAB can
easily manage during the quick routing changes where node movements are very
frequent yet it requires little or no overhead to efficiently complete its tasks
Advances in integrating autonomy with acoustic communications for intelligent networks of marine robots
Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2013Autonomous marine vehicles are increasingly used in clusters for an array of oceanographic
tasks. The effectiveness of this collaboration is often limited by communications:
throughput, latency, and ease of reconfiguration. This thesis argues that improved communication
on intelligent marine robotic agents can be gained from acting on knowledge
gained by improved awareness of the physical acoustic link and higher network layers by
the AUV’s decision making software.
This thesis presents a modular acoustic networking framework, realized through a
C++ library called goby-acomms, to provide collaborating underwater vehicles with an
efficient short-range single-hop network. goby-acomms is comprised of four components
that provide: 1) losslessly compressed encoding of short messages; 2) a set of message
queues that dynamically prioritize messages based both on overall importance and time
sensitivity; 3) Time Division Multiple Access (TDMA) Medium Access Control (MAC) with
automatic discovery; and 4) an abstract acoustic modem driver.
Building on this networking framework, two approaches that use the vehicle’s “intelligence”
to improve communications are presented. The first is a “non-disruptive”
approach which is a novel technique for using state observers in conjunction with an entropy
source encoder to enable highly compressed telemetry of autonomous underwater
vehicle (AUV) position vectors. This system was analyzed on experimental data and implemented
on a fielded vehicle. Using an adaptive probability distribution in combination
with either of two state observer models, greater than 90% compression, relative to
a 32-bit integer baseline, was achieved.
The second approach is “disruptive,” as it changes the vehicle’s course to effect an improvement
in the communications channel. A hybrid data- and model-based autonomous
environmental adaptation framework is presented which allows autonomous underwater
vehicles (AUVs) with acoustic sensors to follow a path which optimizes their ability to
maintain connectivity with an acoustic contact for optimal sensing or communication.I wish to acknowledge the sponsors of this research for their generous support
of my tuition, stipend, and research: the WHOI/MIT Joint Program, the MIT Presidential Fellowship, the Office of Naval Research (ONR) # N00014-08-1-0011, # N00014-08-1-0013, and the ONR PlusNet Program Graduate Fellowship, the Defense Advanced Research Projects Agency (DARPA) (Deep Sea Operations: Applied Physical Sciences (APS) Award # APS 11-15 3352-006, APS 11-15-3352-215 ST 2.6 and 2.7
Wireless Sensor Networks for Underwater Localization: A Survey
Autonomous Underwater Vehicles (AUVs) have widely deployed in marine investigation and ocean exploration in recent years. As the fundamental information, their position information is not only for data validity but also for many real-world applications. Therefore, it is critical for the AUV to have the underwater localization capability. This report is mainly devoted to outline the recent advance- ment of Wireless Sensor Networks (WSN) based underwater localization. Several classic architectures designed for Underwater Acoustic Sensor Network (UASN) are brie y introduced. Acoustic propa- gation and channel models are described and several ranging techniques are then explained. Many state-of-the-art underwater localization algorithms are introduced, followed by the outline of some existing underwater localization systems
- …