• Title/Summary/Keyword: Underwater channel modeling

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MIMO Vector Channel Modeling and Performance Analysis in Underwater Channel Environments (수중 MIMO 벡터 채널 모델링 및 성능 분석)

  • Lee, Deok-Hwan;Ko, Hak-Lim;Lim, Yong-Kon
    • The Journal of the Acoustical Society of Korea
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    • v.26 no.8
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    • pp.426-431
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    • 2007
  • In this paper we have studied the underwater vector channel modeling for MIMO(Multiple Input Multiple Output) to increase the performance and efficiency for ultrasound communication in underwater channel environments. Also we have analyzed the MIMO techniques using the proposed channel modeling. For underwater MIMO channel modeling. experiments were done in real channel environments and the data were analyzed to estimate parameters such as fading, Doppler, time delay, angle of arrival, and receiving power. These were used for modeling of underwater vector channel modeling for MIMO. Additionally, we have analyzed the performance of MIMO systems using our proposed channel models. As a result we could see that the BER has decreased severely with the same SNR when using the MIMO system.

An Approach for Implementation of Underwater Acoustic Communication Channel using 2-D TLM Modeling and Cross-Correlation Function

  • Park, Kyu-Chil;Yoon, Jong-Rak
    • Journal of information and communication convergence engineering
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    • v.8 no.2
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    • pp.163-167
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    • 2010
  • In underwater acoustic communication, acoustic signals from transducers or hydrophones are used. And the underwater acoustic communication channels are very complicated, because of vertical distribution of acoustic velocity according depths, and reflections from boundaries like as surface or bottom. For the implementation of the underwater acoustic communication channel, the image method or ray tracing method have been used. In this paper, we introduce a new approach for implementation of underwater acoustic communication channel using the simulation of the Transmission Line Matrix Modeling and cross-correlations from the input and output signals.

A Study on Constitution of Underwater Acoustic Communication Channel using TLM Modeling (TLM 모델링을 이용한 수중 음향 통신 채널 구현에 관한 연구)

  • Park, Kyu-Chil;Park, Jin-Nam
    • Proceedings of the IEEK Conference
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    • 2007.07a
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    • pp.421-422
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    • 2007
  • In underwater, acoustic waves are used for telecommunication. The communication channels are very complicated, because of the distribution of temperature in depth, reflections from boundaries like as the surface of water and the bottom. We report the constitution of the underwater acoustic channel using the simulation of the Transmission Line Matrix Modeling and cross-correlations from the input and output signals.

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Performance Comparison of Image Transmission in Underwater Acoustic Environment (수중 음향 환경에서의 영상 전송 성능 비교분석)

  • Lee, Seung-Woo
    • Journal of the Korea Institute of Military Science and Technology
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    • v.11 no.3
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    • pp.19-29
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    • 2008
  • Underwater acoustic(UWA) communication is one of the most difficult field in terms of severe channel environments such as multipath propagation, high temporal and spatial variability of channel conditions. Therefore, it is important to model and analyze the characteristics of underwater acoustic channel such as multipath propagation, transmission loss, reverberation, and ambient noise. In this paper, UWA communication channel is modeled with a ray tracing method and applied to image transmission. Quadrature phase shift keying(QPSK) and multichannel decision feedback equalizer(DFE) are utilized as phase-coherent modulation method and equalization technique, respectively. The objective is to improve the performance of the image transmission using vertical sensor array instead of single sensor in the viewpoint of bit error rate(BER), constellation diagram, and received image quality.

An improved sparsity-aware normalized least-mean-square scheme for underwater communication

  • Anand, Kumar;Prashant Kumar
    • ETRI Journal
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    • v.45 no.3
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    • pp.379-393
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    • 2023
  • Underwater communication (UWC) is widely used in coastal surveillance and early warning systems. Precise channel estimation is vital for efficient and reliable UWC. The sparse direct-adaptive filtering algorithms have become popular in UWC. Herein, we present an improved adaptive convex-combination method for the identification of sparse structures using a reweighted normalized leastmean-square (RNLMS) algorithm. Moreover, to make RNLMS algorithm independent of the reweighted l1-norm parameter, a modified sparsity-aware adaptive zero-attracting RNLMS (AZA-RNLMS) algorithm is introduced to ensure accurate modeling. In addition, we present a quantitative analysis of this algorithm to evaluate the convergence speed and accuracy. Furthermore, we derive an excess mean-square-error expression that proves that the AZA-RNLMS algorithm performs better for the harsh underwater channel. The measured data from the experimental channel of SPACE08 is used for simulation, and results are presented to verify the performance of the proposed algorithm. The simulation results confirm that the proposed algorithm for underwater channel estimation performs better than the earlier schemes.

Discrete-time approximation and modeling of a broadband underwater propagation channel based on eigenray analysis (고유 음선 분석에 기반한 광대역 수중음향 전달 채널의 이산시간 근사 및 모의 방법 연구)

  • Shin, Donghoon;Cho, Hyeon-Deok;Kwon, Taekik;Ahn, Jae-Kyun
    • The Journal of the Acoustical Society of Korea
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    • v.39 no.3
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    • pp.216-225
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    • 2020
  • In this paper, broadband underwater propagation channel modeling based on eigenray analysis is discussed. Underwater channels are often formulated in frequency domain time-harmonic signals, which are impractical for simulating broadband signals in time domain. In this regard, time domain modeling of the underwater propagation channel is required for the simulation of broadband signals, for which the eigenray analysis based on ray tracing, resulting in multipath propagation delays in time-domain, is used in this paper. For discrete time system application, the phase, frequency-dependent loss and non-integer sample delays for each eigenray, are approximated by the finite impulse response of the broadband propagation channel.

Performance of Adaptive Equalizer in the Shallow Underwater Acoustic Communication Channel (천해 수중 음향 통신 채널에서 적응 등화기의 성능)

  • Choi, Hyun-Kyu;Lee, Sangmin
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.6 no.1
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    • pp.29-36
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    • 2013
  • The inter-symbol interference(ISI) is one of the main obstacles to reliable high-rate data communication in the shallow underwater acoustic channel. This paper studies on the simulation of adaptive equalizer used as a means of mitigating the ISI in the shallow underwater acoustic communication system. The underwater channel is modeled as a superposition of multiple paths, whose lengths and relative delays are calculated from the channel geometry. Based on this channel model, computer simulations are carried out to investigate the performance of adaptive equalizer in the shallow underwater acoustic channel.

Effectiveness Analysis Tool for Underwater Acoustics Detection in Quasi-static Underwater Acoustics Channel based on Underwater Environmental Information DB (수중 환경 정보 DB 기반 준-정적 수중음향 채널 수중음향 탐지 효과도 분석 모의 도구 구현)

  • Kim, Jang Eun;Han, Dong Seog
    • Journal of the Institute of Electronics and Information Engineers
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    • v.52 no.10
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    • pp.148-158
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    • 2015
  • It is difficult to test a detection system in underwater acoustics channel environments. The system can be evaluated by using simulation analysis tool. In this paper, a simulation tool is proposed to analyze the effectiveness of underwater acoustics detection based on database for real environments. First, the underwater environment is built based on HYCOM underwater environment database. Then, a multipath characteristic is considered through calculating underwater acoustics propagation path/pressure based on the ray theory. Also, hydrophone thermal noise and underwater ambient noise are considered to reflect underwater noise characteristics.

The Modeling and Simulation for Pseudospectral Time-Domain Method Synthetic Environment Underwater Acoustics Channel applied to Underwater Environment Noise Model (수중 환경 소음 모델이 적용된 의사 스펙트럼 시간영역 법 합성환경 수중음향채널 모델링 및 시뮬레이션)

  • Kim, Jang-Eun;Kim, Dong-Gil;Han, Dong-Seog
    • Journal of the Korea Society for Simulation
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    • v.25 no.3
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    • pp.15-28
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    • 2016
  • It is necessary to analyze underwater acoustics channel(UAC) modeling and simulation for underwater weapon system development and acquisition. In order to analyze UAC, there are underwater acoustics propagation numerical analysis models(Ray theory, Parabolic equation, Normal-mode, Wavenumber integration). However, If these models are used for multiple frequency signal analysis, they are inaccurate to calculate result of analysis effectiveness and restricted for signal processing and analysis. In this paper, to overcome this problem, we propose simple/multiple frequency signal analysis model of the Pseudospectral Time-Domain Method synthetic environment UAC applied to underwater environment noise model as like as realistic underwater environment. In order to confirm the validation of the model, we performed the 9 scenarios simulation(4 scenarios of single frequency signal, 4 scenarios of multiple frequency signal, 1 scenario of single/multiple frequency signal like submarine radiated noise) for validation and confirmed the validation of this model through the simulation model.

A Study on the Underwater Channel Model based on a High-Order Finite Difference Method using GPUs (그래픽 프로세서를 이용한 고차 유한 차분식 기반 수중채널모델 연구)

  • Bae, Ho Seuk;Kim, Won-Ki;Son, Su-Uk;Ha, Wansoo
    • Journal of the Korea Society for Simulation
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    • v.30 no.1
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    • pp.11-20
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    • 2021
  • As unmanned underwater systems have recently emerged, a high-speed underwater channel modeling technique, which is one of the most important techniques in the system, has received a lot of attention. In this paper, we proposed a high-speed sound propagation model and verified the applicability through quantitative performance analyses. We used a high-order finite difference method (FDM) for wave propagation modeling in the water, and a domain decomposition method was adopted using multiple general-purpose graphics processing units (GPUs) to increase the calculation efficiency. We compared the results of the model we proposed with the analytic solution in the half-infinite media and results of the Virtual Timeseries Experiment (VirTEX) model, which is based on the ray method. Finally, we analyzed the performance of the model quantitatively using numerical examples. Through quantitative analyses of the improvement in computational performance, we confirmed that the computational speed increases linearly as the number of GPUs increases. The computation times are increased by 2 times and 8 times, respectively, when the domain size of computation and the maximum frequency are doubled. We expect that the proposed high-speed underwater channel modeling technique is able to contribute to the enhancement of national defense as an underwater communication channel model and analysis tool to develop the underwater communication technique for the unmanned underwater system.