scholarly journals Sequence Design Technique for Accurate Timing and Cell ID Estimation in Underwater Acoustic Cellular Systems with a High Doppler

Electronics ◽  
2021 ◽  
Vol 10 (19) ◽  
pp. 2413
Author(s):  
Yeong Jun Kim ◽  
Muhammad Asim ◽  
Tae Ho Im ◽  
Yong Soo Cho
Keyword(s):  
Doppler Shift ◽  
Additive White Gaussian Noise ◽  
Cellular Systems ◽  
Joint Estimation ◽  
Sensor Nodes ◽  
Sequence Length ◽  
Design Technique ◽  
Sequence Design ◽  
Underwater Acoustic ◽  
Simulation Results

In underwater acoustic cellular (UWAC) systems, underwater equipment or sensor nodes (UE/SN) should perform downlink synchronisation and a cell search during the initial access stage using the preambles received from adjacent underwater base stations (UWBSs). The UE/SN needs to estimate accurate timing and cell ID (CID) using the received preambles, and synchronise with a serving UWBS, even in high-Doppler environments. In this paper, a sequence design technique for joint estimation of accurate timing and CID in UWAC systems with a high Doppler is proposed to decrease the receiver complexity and processing time. A generalised Zadoff–Chu sequence is proposed for the preamble design. This sequence is decomposed into multiple short sub-sequences to reduce the effect of Doppler shift on the timing and CID estimation. The performance loss caused by the short sequence length is compensated by combining the sub-sequences using the repetition property of the ZC sequence. The properties (autocorrelation and cross-correlation) of the proposed sequence are derived analytically in the presence of Doppler shift and compared with the simulation results. The simulation results reveal that the proposed technique performs better than existing techniques in both additive white Gaussian noise and multipath channels with a high-Doppler. It is concluded that the proposed technique is suitable for accurate timing estimation and CID detection in UWAC systems with a high Doppler.

scholarly journals Cell ID and Timing Estimation Techniques for Underwater Acoustic Cellular Systems in High-Doppler Environments

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4147
Author(s):  
Muhammad Asim ◽  
Mohammed Saquib Khan ◽  
Tae Ho Im ◽  
Yong Soo Cho
Keyword(s):  
Frequency Modulation ◽  
Doppler Shift ◽  
Base Station ◽  
Ambiguity Function ◽  
Cellular Systems ◽  
Linear Frequency Modulation ◽  
Sensor Nodes ◽  
Underwater Acoustic ◽  
Linear Frequency ◽  
The Time Domain

In an underwater acoustic cellular (UAC) system, underwater equipment or sensor nodes need to detect the identity of an underwater base station (UBS) and synchronise it with a serving UBS. It is known that, in an underwater acoustic channel, the temporal variability of the ocean coupled with the low speed of sound in water may induce a significant Doppler shift. In this paper, two different types of cell search techniques (CSTs) are proposed to detect the cell ID and correct timing of the UBS in UAC systems with a Doppler shift: CST based on linear frequency modulation with full bandwidth in the time domain (LFM-FT) and CST based on linear frequency modulation in the frequency domain (LFM-FF). The performances (auto-correlation, cross-correlation, ambiguity function, and cross ambiguity function) of the proposed techniques are analysed and compared with simulation results. It is demonstrated by simulation that the proposed techniques perform better than previous techniques in both AWGN and multipath channels when a Doppler shift exists. It is also shown that the LFM-FF-CST achieves the best performance in the presence of a Doppler shift and is suitable for mobile UAC systems.

Design Technique of High Power Efficiency LLC DC-DC Converters for Photovoltaic Cells

2018 ◽  
Vol 2 (1) ◽  
pp. 30
Author(s):  
Hisatsugu Kato ◽  
Yoichi Ishizuka ◽  
Kohei Ueda ◽  
Shotaro Karasuyama ◽  
Atsushi Ogasahara
Keyword(s):  
High Power ◽  
Power Efficiency ◽  
Photovoltaic Cells ◽  
Input Voltage ◽  
Design Technique ◽  
Load Range ◽  
Voltage Range ◽  
Simulation Results ◽  
Secondary Side ◽  
High Power Efficiency

This paper proposes a design technique of high power efficiency LLC DC-DC Converters for Photovoltaic Cells. The secondary side circuit and transformer fabrication of proposed circuit are optimized for overcoming the disadvantage of limited input voltage range and, realizing high power efficiency over a wide load range of LLC DC-DC converters. The optimized technique is described with theoretically and with simulation results. Some experimental results have been obtained with the prototype circuit designed for the 80 - 400 V input voltage range. The maximum power efficiency is 98 %.

scholarly journals Robust Silent Localization of Underwater Acoustic Sensor Network Using Mobile Anchor(s)

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 727
Author(s):  
Rahul Mourya ◽  
Mauro Dragone ◽  
Yvan Petillot
Keyword(s):  
Channel Model ◽  
Low Cost ◽  
Sensor Nodes ◽  
Noise Model ◽  
Robust Estimator ◽  
Acoustic Sensor ◽  
Underwater Acoustic ◽  
Acoustic Channel ◽  
Localization Scheme ◽  
Mobile Anchor

Underwater acoustic sensor networks (UWASNs) can revolutionize the subsea domain by enabling low-cost monitoring of subsea assets and the marine environment. Accurate localization of the UWASNs is essential for these applications. In general, range-based localization techniques are preferred for their high accuracy in estimated locations. However, they can be severely affected by variable sound speed, multipath spreading, and other effects of the acoustic channel. In addition, an inefficient localization scheme can consume a significant amount of energy, reducing the effective life of the battery-powered sensor nodes. In this paper, we propose robust, efficient, and practically implementable localization schemes for static UWASNs. The proposed schemes are based on the Time-Difference-of-Arrival (TDoA) measurements and the nodes are localized passively, i.e., by just listening to beacon signals from multiple anchors, thus saving both the channel bandwidth and energy. The robustness in location estimates is achieved by considering an appropriate statistical noise model based on a plausible acoustic channel model and certain practical assumptions. To overcome the practical challenges of deploying and maintaining multiple permanent anchors for TDoA measurements, we propose practical schemes of using a single or multiple surface vehicles as virtual anchors. The robustness of localization is evaluated by simulations under realistic settings. By combining a mobile anchor(s) scheme with a robust estimator, this paper presents a complete package of efficient, robust, and practically usable localization schemes for low-cost UWASNs.

scholarly journals Optimized Gateway Placement for Interference Cancellation in Transmit-Only LPWA Networks

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3884 ◽  
Author(s):  
Hongxian Tian ◽  
Mary Weitnauer ◽  
Gedeon Nyengele
Keyword(s):  
Low Power ◽  
Sensor Network ◽  
Interference Cancellation ◽  
Greedy Algorithms ◽  
Sensor Nodes ◽  
Wide Area ◽  
Delivery Ratio ◽  
Large Network ◽  
Packet Delivery ◽  
Simulation Results

We study the placement of gateways in a low-power wide-area sensor network, when the gateways perform interference cancellation and when the model of the residual error of interference cancellation is proportional to the power of the packet being canceled. For the case of two sensor nodes sending packets that collide, by which we mean overlap in time, we deduce a symmetric two-crescent region wherein a gateway can decode both collided packets. For a large network of many sensors and multiple gateways, we propose two greedy algorithms to optimize the locations of the gateways. Simulation results show that the gateway placements by our algorithms achieve lower average contention, which means higher packet delivery ratio in the same conditions, than when gateways are naively placed, for several area distributions of sensors.

scholarly journals Elephant Herding Optimization for Energy-Based Localization

2018 ◽  
Author(s):  
Sérgio Correia ◽  
Marko Beko ◽  
Luís Cruz ◽  
Slavisa Tomic
Keyword(s):  
Source Localization ◽  
Wireless Sensors ◽  
Performance Comparison ◽  
Sensor Nodes ◽  
Convex Relaxations ◽  
Noisy Environments ◽  
New Approach ◽  
Metaheuristic Methods ◽  
Simulation Results ◽  
First Time

This work addresses the energy-based source localization problem in wireless sensors networks. Instead of circumventing the maximum likelihood (ML) problem by applying convex relaxations and approximations (like all existing approaches do), we here tackle it directly by the use of metaheuristics. To the best of our knowledge, this is the first time that metaheuristics is applied to this type of problems. More specifically an elephant herding optimization (EHO) algorithm is applied. Through extensive simulations, the key parameters of the EHO algorithm are optimized such that they match the energy decay model between two sensor nodes. A detailed analysis of the computational complexity is presented, as well as performance comparison between the proposed algorithm and existing non-metaheuristic ones. Simulation results show that the new approach significantly outperforms the existing solutions in noisy environments, encouraging further improvement and testing of metaheuristic methods.

scholarly journals BER Performance Analysis of Non-Coherent Q-Ary Pulse Position Modulation Receivers on AWGN Channel

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6102
Author(s):  
Xianhua Shi ◽  
Yimao Sun ◽  
Jie Tian ◽  
Maolin Chen ◽  
Youjiang Liu ◽  
...  
Keyword(s):  
Gaussian Noise ◽  
Additive White Gaussian Noise ◽  
Theoretical Formula ◽  
Pulse Position Modulation ◽  
Error Performance ◽  
Optimal Receiver ◽  
Awgn Channel ◽  
Simulation Results ◽  
The Relationship ◽  
Better Than

This paper introduces the structure of a Q-ary pulse position modulation (PPM) signal and presents a noncoherent suboptimal receiver and a noncoherent optimal receiver. Aiming at addressing the lack of an accurate theoretical formula of the bit error rate (BER) of a Q-ary PPM receiver in the additive white Gaussian noise (AWGN) channel in the existing literature, the theoretical formulas of the BER of a noncoherent suboptimal receiver and noncoherent optimal receiver are derived, respectively. The simulation results verify the correctness of the theoretical formulas. The theoretical formulas can be applied to a Q-ary PPM system including binary PPM. In addition, the analysis shows that the larger the Q, the better the error performance of the receiver and that the error performance of the optimal receiver is about 2 dB better than that of the suboptimal receiver. The relationship between the threshold coefficient of the suboptimal receiver and the error performance is also given.

scholarly journals Evaluation of AODV and DYMO Routing Protocol using Generic, Micaz and Micamotes Energy Conservation Models in AWSN with Static and Mobile Scenario

2019 ◽  
Vol 20 (4) ◽  
pp. 653-662 ◽  
Author(s):  
Suresh Kumar ◽  
Kiran Dhull ◽  
Deepak Sharma ◽  
Payal Arora ◽  
Sandeep Dahiya
Keyword(s):  
Wireless Sensor Networks ◽  
Energy Conservation ◽  
Routing Protocol ◽  
Energy Model ◽  
Sensor Nodes ◽  
Wireless Sensor ◽  
End To End Delay ◽  
Adhoc Networks ◽  
Simulation Results ◽  
Aodv Routing Protocol

Adhoc Wireless Sensor Networks (AWSN’s) have found an increasing utility in various applications. In AWSN, sensor nodes are arranged in a topology which is suitable to the requirement of the nature of task. As the sensors are not connected in a fixed manner, their networking, location and functioning keeps on changing based on the situation due to which these are called Adhoc networks. The biggest challenge is to keep the sensors working for longer life by conserving their energy. Therefore, a suitable routing protocol needs to be selected to meet the energy conservation requirement at different nodes. In the present paper, we have evaluated the three energy conservation models i.e. Generic, Micaz and Micamotes for AODV and DYMO routing protocol. The evaluation is carried out using the parameter metrices: (i) Average End-to-End Delay (AEED), (ii) Throughput (iii) Energy consumed in Transmit mode and Receive mode. Based on the simulation results, it has been observed that Micamotes energy model using AODV routing protocol performs better in terms of energy consumption upto 42.99% and 29.90 % in transmit and upto 59.24% and 33.96 % in receive mode respectively as compared to Generic and Micaz energy model.

scholarly journals Data Gathering from a Multimodal Dense Underwater Acoustic Sensor Network Deployed in Shallow Fresh Water Scenarios

2019 ◽  
Vol 8 (4) ◽  
pp. 55 ◽  
Author(s):  
Alberto Signori ◽  
Filippo Campagnaro ◽  
Fabian Steinmetz ◽  
Bernd-Christian Renner ◽  
Michele Zorzi
Keyword(s):  
Data Collection ◽  
Low Cost ◽  
World Ocean ◽  
Environmental Data ◽  
Sensor Nodes ◽  
Real Field ◽  
Acoustic Sensor ◽  
Adaptive Mechanism ◽  
Underwater Acoustic ◽  
Inspection Service

The Robotic Vessels as-a-Service (RoboVaaS) project intends to exploit the most advanced communication and marine vehicle technologies to revolutionize shipping and near-shore operations, offering on-demand and cost-effective robotic-aided services. In particular, the RoboVaaS vision includes a ship hull inspection service, a quay walls inspection service, an antigrounding service, and an environmental and bathymetry data collection service. In this paper, we present a study of the underwater environmental data collection service, performed by a low-cost autonomous vehicle equipped with both a commercial modem and a very low-cost acoustic modem prototype, the smartPORT Acoustic Underwater Modem (AHOI). The vehicle mules the data from a network of low cost submerged acoustic sensor nodes to a surface sink. To this end, an underwater acoustic network composed by both static and moving nodes has been implemented and simulated with the DESERT Underwater Framework, where the performance of the AHOI modem has been mapped in the form of lookup tables. The performance of the AHOI modem has been measured near the Port of Hamburg, where the RoboVaaS concept will be demonstrated with a real field evaluation. The transmission with the commercial modem, instead, has been simulated with the Bellhop ray tracer thanks to the World Ocean Simulation System (WOSS), by considering both the bathymetry and the sound speed profile of the Port of Hamburg. The set up of the polling-based MAC protocol parameters, such as the maximum backoff time of the sensor nodes, appears to be crucial for the network performance, in particular for the low-cost low-rate modems. In this work, to tune the maximum backoff time during the data collection mission, an adaptive mechanism has been implemented. Specifically, the maximum backoff time is updated based on the network density. This adaptive mechanism results in an 8% improvement of the network throughput.

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