scholarly journals A Graph Localization Approach for Underwater Sensor Networks to Assist a Diver in Distress

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1306
Author(s):  
Roee Diamant ◽  
Roberto Francescon
Keyword(s):  
Propagation Delay ◽  
Upper And Lower Bounds ◽  
Underwater Acoustic Communication ◽  
Underwater Sensor Networks ◽  
Water Tank ◽  
Localization Accuracy ◽  
Rateless Coding ◽  
Scuba Divers ◽  
Network Topologies ◽  
Localization Approach

In this paper, we focus on the problem of locating a scuba diver in distress using a sensor network. Without GPS reception, submerged divers in distress will transmit SOS messages using underwater acoustic communication. The study goal is to enable the quick and reliable location of a diver in distress by his fellow scuba divers. To this purpose, we propose a distributed scheme that relies on the propagation delay information of these acoustic SOS messages in the scuba divers’ network to yield a range and bearing evaluation to the diver in distress by any neighboring diver. We formalize the task as a non-convex, multi-objective graph localization constraint optimization problem. The solution finds the best configuration of the nodes’ graph under constraints in the form of upper and lower bounds derived from the inter-connections between the graph nodes/divers. Considering the need to rapidly propagate the SOS information, we flood the network with the SOS packet, while also using rateless coding to leverage information from colliding packets, and to utilize time instances when collisions occur for propagation delay evaluation. Numerical results show a localization accuracy on the order of a few meters, which contributes to quickly locating the diver in distress. Similar results were demonstrated in a controlled experiment in a water tank, and by playback data from a sea experiment for five network topologies.

scholarly journals Hybrid Localization Approach for Underwater Sensor Networks

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Pei-Hsuan Tsai ◽  
Rong-Guei Tsai ◽  
Shiuan-Shiang Wang
Keyword(s):  
Sensor Networks ◽  
Mobile Networks ◽  
Kinematic Model ◽  
Mobility Model ◽  
Communication Overhead ◽  
Underwater Sensor Networks ◽  
Localization Accuracy ◽  
Hybrid Localization ◽  
Localization Approach ◽  
Sensor Locations

Underwater Wireless Sensor Networks (UWSNs) are widely used to collect data in the marine environment. Location and time are essential aspects when sensors collect data, particularly in the case of location-aware data. Many studies on terrestrial sensor networks consider sensor locations as the locations where data is collected and focus on sensor positioning when sensors are fixed. However, underwater sensors are mobile networks and the sensor locations change continuously. Localization schemes designed for static sensor networks need to run periodically to update locations and consume considerable sensor power and increase the communication overhead; hence, they cannot be applied to UWSNs. This paper presents a hybrid localization approach with data-location correction, called Data Localization Correction Approach (DLCA), which positions data without additional communication overhead and power consumption on sensors. Without loss of generality, we simulate the ocean environment based on a kinematic model and meandering current mobility model and conduct extensive simulations. Our results show that DLCA can significantly reduce communication costs, while maintaining relatively high localization accuracy.

scholarly journals Research and Fabrication of Broadband Ring Flextensional Underwater Transducer

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1548
Author(s):  
Jiuling Hu ◽  
Lianjin Hong ◽  
Lili Yin ◽  
Yu Lan ◽  
Hao Sun ◽  
...  
Keyword(s):  
High Speed ◽  
Structural Parameters ◽  
Low Frequency ◽  
Flexural Vibration ◽  
Underwater Acoustic Communication ◽  
Voltage Response ◽  
Water Tank ◽  
Spherical Cap ◽  
Finite Element Software ◽  
Underwater Transducer

At present, high-speed underwater acoustic communication requires underwater transducers with the characteristics of low frequency and broadband. The low-frequency transducers also are expected to be low-frequency directional for realization of point-to-point communication. In order to achieve the above targets, this paper proposes a new type of flextensional transducer which is constructed of double mosaic piezoelectric ceramic rings and spherical cap metal shells. The transducer realizes broadband transmission by means of the coupling between radial vibration of the piezoelectric rings and high-order flexural vibration of the spherical cap metal shells. The low-frequency directional transmission of the transducer is realized by using excitation signals with different amplitude and phase on two mosaic piezoelectric rings. The relationship between transmitting voltage response (TVR), resonance frequency and structural parameters of the transducer is analyzed by finite element software COMSOL. The broadband performance of the transducer is also optimized. On this basis, the low-frequency directivity of the transducer is further analyzed and the ratio of the excitation signals of the two piezoelectric rings is obtained. Finally, a prototype of the broadband ring flextensional underwater transducer is fabricated according to the results of simulation. The electroacoustic performance of the transducer is tested in an anechoic water tank. Experimental results show that the maximum TVR of the transducer is 147.2 dB and the operation bandwidth is 1.5–4 kHz, which means that the transducer has good low-frequency, broadband transmission capability. Meanwhile, cardioid directivity is obtained at 1.4 kHz and low-frequency directivity is realized.

DAFI

2021 ◽  
Vol 5 (4) ◽  
pp. 1-21
Author(s):  
Hang Li ◽  
Xi Chen ◽  
Ju Wang ◽  
Di Wu ◽  
Xue Liu
Keyword(s):  
Indoor Localization ◽  
Domain Adaptation ◽  
Target Domain ◽  
Localization Accuracy ◽  
Source Domain ◽  
Fine Grained ◽  
Time Signals ◽  
Environmental Variations ◽  
Device Free ◽  
Localization Approach

WiFi-based Device-free Passive (DfP) indoor localization systems liberate their users from carrying dedicated sensors or smartphones, and thus provide a non-intrusive and pleasant experience. Although existing fingerprint-based systems achieve sub-meter-level localization accuracy by training location classifiers/regressors on WiFi signal fingerprints, they are usually vulnerable to small variations in an environment. A daily change, e.g., displacement of a chair, may cause a big inconsistency between the recorded fingerprints and the real-time signals, leading to significant localization errors. In this paper, we introduce a Domain Adaptation WiFi (DAFI) localization approach to address the problem. DAFI formulates this fingerprint inconsistency issue as a domain adaptation problem, where the original environment is the source domain and the changed environment is the target domain. Directly applying existing domain adaptation methods to our specific problem is challenging, since it is generally hard to distinguish the variations in the different WiFi domains (i.e., signal changes caused by different environmental variations). DAFI embraces the following techniques to tackle this challenge. 1) DAFI aligns both marginal and conditional distributions of features in different domains. 2) Inside the target domain, DAFI squeezes the marginal distribution of every class to be more concentrated at its center. 3) Between two domains, DAFI conducts fine-grained alignment by forcing every target-domain class to better align with its source-domain counterpart. By doing these, DAFI outperforms the state of the art by up to 14.2% in real-world experiments.

scholarly journals Receiver-Initiated Handshaking MAC Based on Traffic Estimation for Underwater Sensor Networks ‡

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3895 ◽  
Author(s):  
Yuan Dong ◽  
Lina Pu ◽  
Yu Luo ◽  
Zheng Peng ◽  
Haining Mo ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Sensor Networks ◽  
Propagation Delay ◽  
Mac Protocols ◽  
Underwater Sensor Networks ◽  
Medium Access ◽  
The Status ◽  
Efficient Data ◽  
Traffic Estimation ◽  
Delay Tolerant

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However, the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-based receiver-initiated MAC (TERI-MAC) to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications.

Covert Underwater Acoustic Communication System Using Parametric Array

2019 ◽  
Vol 53 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Anbang Zhao ◽  
Yue Cheng ◽  
Tiansi An ◽  
Juan Hui
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Low Frequency ◽  
Nonlinear Behavior ◽  
Beam Width ◽  
Point Of View ◽  
Underwater Acoustic Communication ◽  
Water Tank ◽  
Narrow Beam ◽  
Underwater Acoustic ◽  
Parametric Array

AbstractA novel and efficient covert underwater acoustic (UWA) communication scheme using an acoustic parametric array and orthogonal frequency division multiplexing (OFDM) system is presented. The proposed system is robust and can easily be implemented in the ocean environment. The system is also very useful in military applications where the secrecy of transmission signal and location of the transmitter are extremely important. The paper exploits the difference frequency generated by the acoustic parametric array due to the nonlinear behavior of an underwater medium. Besides the lightness and compactness, the parametric array also possesses the advantage of being low-frequency, broadband, highly directive, and narrow beam with no side lobes. The narrow beam width also helps to secure the data from a spatial point of view. Experiments have been performed in a water tank, and the results are presented to show the effectiveness of the proposed scheme.

scholarly journals Improving Both Energy and Time Efficiency of Depth-Based Routing for Underwater Sensor Networks

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Boyu Diao ◽  
Yongjun Xu ◽  
Zhulin An ◽  
Fei Wang ◽  
Chao Li
Keyword(s):  
Sensor Network ◽  
Routing Protocol ◽  
Energy Efficient ◽  
Optimal Path ◽  
Three Dimensional ◽  
Geographic Routing ◽  
Underwater Acoustic Communication ◽  
Low Latency ◽  
Depth Information ◽  
Underwater Sensor Networks

Underwater Sensor Network (UWSN) is a representative three-dimensional wireless sensor network. Due to the unique characteristics of underwater acoustic communication, providing energy-efficient and low-latency routing protocols for UWSNs is challenging. Major challenges are water currents, limited resources, and long acoustic propagation delay. Network topology of UWSNs is dynamic and complex as sensors have always been moving with currents. Some proposed protocols adopt geographic routing to address this problem, but three-dimensional localization is hard to obtain in underwater environment. As depth-based routing protocol (DBR) uses depth information only which is much more easier to obtain, it is more practical for UWSNs. However, depth information is not enough to restrict packets to be forwarded within a particular area. Packets may be forwarded through multiple paths which might cause energy waste and increase end-to-end delay. In this paper, we introduce underwater time of arrival (ToA) ranging technique to address the problem above. To maintain all the original advantages of DBR, we make the following contributions: energy-efficient depth-based routing protocol that reduces redundancy energy cost in some blind zones; low-latency depth-based routing protocol that is able to deliver a packet through an optimal path. The proposed protocols are validated through extensive simulations.

scholarly journals A MAC Protocol of Concurrent Scheduling Based on Spatial-Temporal Uncertainty for Underwater Sensor Networks

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Xin Liu ◽  
Xiujuan Du ◽  
Meiju Li ◽  
Lijuan Wang ◽  
Chong Li
Keyword(s):  
Energy Consumption ◽  
Sensor Networks ◽  
Mac Protocol ◽  
Average Energy ◽  
Propagation Delay ◽  
Spatial Uncertainty ◽  
Underwater Sensor Networks ◽  
Temporal Uncertainty ◽  
Concurrent Scheduling ◽  
Time Division

Underwater sensor networks (UWSNs) are characterized by large energy consumption, limited power supply, low bit rate, and long propagation delay, as well as spatial-temporal uncertainty, which present both challenges and opportunities for media access control (MAC) protocol design. The time-division transmissions can effectively avoid collisions since different nodes transmit packets at different period of time. Nevertheless, in UWSNs with long propagation delay, in order to avoid collisions, the period of time is subject to be long enough, which results in poor channel utilization and low throughput. In view of the long and different propagation delay between a receiving node and multiple sending nodes in UWSNs, as long as there is no collision at the receiving node, multiple sending nodes can transmit packets simultaneously. Therefore, in this paper, we propose a MAC protocol of concurrent scheduling based on spatial-temporal uncertainty called CSSTU-MAC (concurrent scheduling based on spatial-temporal uncertainty MAC) for UWSNs. The CSSTU-MAC protocol utilizes the characteristics of temporal-spatial uncertainty as well as long propagation delay in UWSNs to achieve concurrent transmission and collision avoidance. Simulation results show that the CSSTU-MAC protocol outperforms the existing MAC protocol with time-division transmissions in terms of average energy consumption and network throughput.

scholarly journals LEARNING MAPS FOR OBJECT LOCALIZATION USING VISUAL-INERTIAL ODOMETRY

2020 ◽  
Vol V-1-2020 ◽  
pp. 343-350
Author(s):  
B. Zha ◽  
A. Yilmaz
Keyword(s):  
Object Motion ◽  
Spatial Uncertainty ◽  
Object Localization ◽  
Abstract Objects ◽  
Motion Patterns ◽  
Localization Accuracy ◽  
Single Location ◽  
Trajectory Classification ◽  
Potential Motion ◽  
Localization Approach

Abstract. Objects follow designated path on maps, such as vehicles travelling on a road. This observation signifies topological representation of objects’ motion on the map. Considering the position of object is unknown initially, as it traverses the map by moving and turning, the spatial uncertainty of its whereabouts reduces to a single location as the motion trajectory would fit only to a certain map trajectory. Inspired by this observation, we propose a novel end-to-end localization approach based on topological maps that exploits the object motion and learning the map using an recurrent neural network (RNN) model. The core of the proposed method is to learn potential motion patterns from the map and perform trajectory classification in the map’s edge-space. Two different trajectory representations, namely angle representation and augmented angle representation (incorporates distance traversed) are considered and an RNN is trained from the map for each representation to compare their performances. The localization accuracy in the tested map for the angle and augmented angle representations are 90.43% and 96.22% respectively. The results from the actual visual-inertial odometry have shown that the proposed approach is able to learn the map and localize objects based on their motion.

Performance Evaluation of Depth Adjustment and Void Aware Pressure Routing (DA-VAPR) Protocol for Underwater Wireless Sensor Networks

2019 ◽  
Vol 63 (2) ◽  
pp. 193-202
Author(s):  
N Ganesh
Keyword(s):  
Packet Loss ◽  
Optimization Technique ◽  
Propagation Delay ◽  
Wireless Sensor ◽  
Ocean Current ◽  
Underwater Acoustic Communication ◽  
Greedy Forwarding ◽  
Main Challenge ◽  
Minimum Displacement ◽  
Forwarding Strategy

Abstract Underwater wireless sensor network (UWSN) has gained its popularity as a powerful technology for monitoring oceans, sea and river. The sensor node drifting along with ocean current offers 4D (space and time) monitoring for real-time underwater application. However, the main challenge arises from the underwater acoustic communication that results in high propagation delay, packet loss and overhead in the network. In order to overcome these issues, a depth adjustment and void aware pressure routing protocol is proposed for UWSN. A greedy forwarding strategy is used to forward the packet. In case a node fails to forward the packet using greedy forwarding strategy, then it immediately switches to the recovery mode. In the recovery mode, the node determines the new depth using particle swarm optimization technique. The global best value gives the new depth with minimum displacement. The void node forwards the packet with minimum displacement without any packet loss and delay.

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