6 research outputs found
Analysis of 3D Localization in Underwater Optical Wireless Networks with Uncertain Anchor Positions
Localization accuracy is of paramount importance for the proper operation of
underwater optical wireless sensor networks (UOWSNs). However, underwater
localization is prone to hostile environmental impediments such as drifts due
to the surface and deep currents. These cause uncertainty in the deployed
anchor node positions and pose daunting challenges to achieve accurate location
estimations. Therefore, this paper analyzes the performance of
three-dimensional (3D) localization for UOWSNs and derive a closed-form
expression for the Cramer Rao lower bound (CRLB) by using time of arrival (ToA)
and angle of arrival (AoA) measurements under the presence of uncertainty in
anchor node positions. Numerical results validate the analytical findings by
comparing the localization accuracy in scenarios with and without anchor nodes
position uncertainty. Results are also compared with the linear least square
(LSS) method and weighted LLS (WLSS) method
End-to-End Performance Analysis of Underwater Optical Wireless Relaying and Routing Techniques Under Location Uncertainty
On the contrary of low speed and high delay acoustic systems, underwater
optical wireless communication (UOWC) can deliver a high speed and low latency
service at the expense of short communication ranges. Therefore, multihop
communication is of utmost importance to improve degree of connectivity and
overall performance of underwater optical wireless networks (UOWNs). In this
regard, this paper investigates relaying and routing techniques and provides
their end-to-end (E2E) performance analysis under the location uncertainty. To
achieve robust and reliable links, we first consider adaptive beamwidths and
derive the divergence angles under the absence and presence of a
pointing-acquisitioning-and-tracking (PAT) mechanism. Thereafter, important E2E
performance metrics (e.g., data rate, bit error rate, transmission power,
amplifier gain, etc.) are obtained for two potential relaying techniques;
decode & forward (DF) and optical amplify & forward (AF). We develop
centralized routing schemes for both relaying techniques to optimize E2E rate,
bit error rate, and power consumption. Alternatively, a distributed routing
protocol, namely Light Path Routing (LiPaR), is proposed by leveraging the
range-beamwidth tradeoff of UOWCs. LiPaR is especially shown to be favorable
when there is no PAT mechanism and available network information. In order to
show the benefits of multihop communications, extensive simulations are
conducted to compare different routing and relaying schemes under different
network parameters and underwater environments
Outlier Detection and Optimal Anchor Placement for 3D Underwater Optical Wireless Sensor Networks Localization
Location is one of the basic information required for underwater optical
wireless sensor networks (UOWSNs) for different purposes such as relating the
sensing measurements with precise sensor positions, enabling efficient
geographic routing techniques, and sustaining link connectivity between the
nodes. Even though various two-dimensional UOWSNs localization methods have
been proposed in the past, the directive nature of optical wireless
communications and three-dimensional (3D) deployment of sensors require to
develop 3D underwater localization methods. Additionally, the localization
accuracy of the network strongly depends on the placement of the anchors.
Therefore, we propose a robust 3D localization method for partially connected
UOWSNs which can accommodate the outliers and optimize the placement of the
anchors to improve the localization accuracy. The proposed method formulates
the problem of missing pairwise distances and outliers as an optimization
problem which is solved through half quadratic minimization. Furthermore,
analysis is provided to optimally place the anchors in the network which
improves the localization accuracy. The problem of optimal anchor placement is
formulated as a combination of Fisher information matrices for the sensor nodes
where the condition of D-optimality is satisfied. The numerical results
indicate that the proposed method outperforms the literature substantially in
the presence of outliers.Comment: 14 pages, 11 figures, Accepted for Publication in IEEE Transactions
on Communication
Towards the Internet of Underground Things: A Systematic Survey
This paper provides recent advances in the area of Internet of Underground
Things (IoUT) with emphasis on enabling communication technologies, networking
issues, and localization techniques. IoUT is enabled by underground things
(sensors), communication technology, and networking protocols. This new
paradigm of IoUT facilitates the integration of sensing and communication in
the underground environment for various industries such as oil and gas,
agriculture, seismic mapping, and border monitoring. These applications require
to gather relevant information from the deployed underground things. However,
the harsh underground propagation environment including sand, rock, and
watersheds do not allow the use of single communication technology for
information transfer between the surface and the underground things. Therefore,
various wireless and wired communication technologies are used for underground
communication. The wireless technologies are based on acoustic waves,
electromagnetic waves, magnetic induction and visible light communication while
the wired technologies use coaxial cable and optical fibers. In this paper,
state-of-art communication technologies are surveyed, and the respective
networking and localization techniques for IoUT are presented. Moreover, the
advances and applications of IoUT are also reported. Also, new research
challenges for the design and implementation of IoUT are identified.Comment: IEEE Communication Surveys & Tutorial
A State-of-the-Art Survey on Multidimensional Scaling Based Localization Techniques
Current and future wireless applications strongly rely on precise real-time
localization. A number of applications such as smart cities, Internet of Things
(IoT), medical services, automotive industry, underwater exploration, public
safety, and military systems require reliable and accurate localization
techniques. Generally, the most popular localization/ positioning system is the
Global Positioning System (GPS). GPS works well for outdoor environments but
fails in indoor and harsh environments. Therefore, a number of other wireless
local localization techniques are developed based on terrestrial wireless
networks, wireless sensor networks (WSNs) and wireless local area networks
(WLANs). Also, there exist localization techniques which fuse two or more
technologies to find out the location of the user, also called signal of
opportunity based localization. Most of the localization techniques require
ranging measurements such as time of arrival (ToA), time difference of arrival
(TDoA), direction of arrival (DoA) and received signal strength (RSS). There
are also range-free localization techniques which consider the proximity
information and do not require the actual ranging measurements. Dimensionality
reduction techniques are famous among the range free localization schemes.
Multidimensional scaling (MDS) is one of the dimensionality reduction technique
which has been used extensively in the recent past for wireless networks
localization. In this paper, a comprehensive survey is presented for MDS and
MDS based localization techniques in WSNs, Internet of Things (IoT), cognitive
radio networks, and 5G networks.Comment: Accepted in IEEE Communications Surveys and Tutorial
Underwater Optical Wireless Communications, Networking, and Localization: A Survey
Underwater wireless communications can be carried out through acoustic, radio
frequency (RF), and optical waves. Compared to its bandwidth limited acoustic
and RF counterparts, underwater optical wireless communications (UOWCs) can
support higher data rates at low latency levels. However, severe aquatic
channel conditions (e.g., absorption, scattering, turbulence, etc.) pose great
challenges for UOWCs and significantly reduce the attainable communication
ranges, which necessitates efficient networking and localization solutions.
Therefore, we provide a comprehensive survey on the challenges, advances, and
prospects of underwater optical wireless networks (UOWNs) from a layer by layer
perspective which includes: 1) Potential network architectures; 2) Physical
layer issues including propagation characteristics, channel modeling, and
modulation techniques 3) Data link layer problems covering link configurations,
link budgets, performance metrics, and multiple access schemes; 4) Network
layer topics containing relaying techniques and potential routing algorithms;
5) Transport layer subjects such as connectivity, reliability, flow and
congestion control; 6) Application layer goals and state-of-the-art UOWN
applications, and 7) Localization and its impacts on UOWN layers. Finally, we
outline the open research challenges and point out the future directions for
underwater optical wireless communications, networking, and localization
research.Comment: This manuscript is submitted to IEEE Communication Surveys and
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