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Shipborne Underwater Acoustic Communication System and Sea Trials with Submersible Shenhai Yongshi 被引量:9
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作者 WU Yan-bo ZHU Min +5 位作者 LIANG Tao WANG Wei YANG Bo HANG Linyuan LI Xin-guo LIU Ye-yao 《China Ocean Engineering》 SCIE EI CSCD 2018年第6期746-754,共9页
The Shipborne acoustic communication system of the submersible Shenhai Yongshi works in vertical, horizontal and slant channels according to the relative positions. For ease of use, an array combined by a vertical-con... The Shipborne acoustic communication system of the submersible Shenhai Yongshi works in vertical, horizontal and slant channels according to the relative positions. For ease of use, an array combined by a vertical-cone directional transducer and a horizontal-toroid one is installed on the mothership. Improved techniques are proposed to combat adverse channel conditions, such as frequency selectivity, non-stationary ship noise, and Doppler effects of the platform’s nonlinear movement. For coherent modulation, a turbo-coded single-carrier scheme is used. In the receiver, the sparse decision-directed Normalized Least-Mean-Square soft equalizer automatically adjusts the tap pattern and weights according to the multipath structure, the two receivers’ asymmetry, the signal’s frequency selectivity and the noise’s spectrum fluctuation. The use of turbo code in turbo equalization significantly suppresses the error floor and decreases the equalizer’s iteration times, which is verified by both the extrinsic information transfer charts and bit-error-rate performance. For noncoherent modulation, a concatenated error correction scheme of nonbinary convolutional code and Hadamard code is adopted to utilize full frequency diversity. Robust and lowcomplexity synchronization techniques in the time and Doppler domains are proposed. Sea trials with the submersible to a maximum depth of over 4500 m show that the shipborne communication system performs robustly during the adverse conditions. From the ten-thousand communication records in the 28 dives in 2017, the failure rate of the coherent frames and that of the noncoherent packets are both below 10%, where both synchronization errors and decoding errors are taken into account. 展开更多
关键词 underwater acoustic communication turbo equalization human occupied vehicle high-speed shipborne communication system
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Fractional Fourier domain hopped communication method based on chirp modulation for underwater acoustic channels 被引量:11
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作者 Xingbin Tu Xiaomei Xu +2 位作者 Zheguang Zou Liangliang Yang Jianming Wu 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2017年第3期449-456,共8页
To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acousti... To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acoustic communications. An FrFD frequency-hopped communication method based on chirp modulation, namely multiple chirp shift keying-FrFD hopping (MCSK-FrFDH), is proposed for underwater acoustic channels. Validated by both simulations and experimental results, this method can reach a bandwidth efficiency twice more than conventional frequency-hopped methods with the same data rate and anti-multipath capability, suggesting that the proposed method achieves a better performance than the traditional frequency hopped communication in underwater acoustic communication channels. Results also show that in practical scenarios, the MCSK-FrFDH system with longer symbol length performs better at the low signal-to-noise ratio (SNR), while the system with larger frequency sweeping range performs better at a high SNR. 展开更多
关键词 underwater acoustic communication fractional Fourier domain (FrFD) frequency hopping chirp signal
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Frequency Diversity for OFDM Mobile Communication via Underwater Acoustic Channels 被引量:7
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作者 Gang Qiao Wei Wang +2 位作者 Ran Guo Rehan Khan Yue Wang 《Journal of Marine Science and Application》 2012年第1期126-133,共8页
The major constraint on the performance of orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and t... The major constraint on the performance of orthogonal frequency division multiplexing (OFDM) based underwater acoustic (UWA) communication is to keep subcarriers orthogonal. In this paper, Doppler estimation and the respective compensation technique along with various diversity techniques were deliberated for OFDM-based systems best suited for underwater wireless information exchange. In practice, for mobile communication, adjustment and tuning of transducers in order to get spatial diversity is extremely difficult. Considering the relatively low coherence bandwidth in UWA, the frequency diversity design with the Doppler compensation function was elaborated here. The outfield experiments of mobile underwater acoustic communication (UWAC) based on OFDM were carried out with 0.17 bit/(s-Hz) spectral efficiency. The validity and the dependability of the scheme were also analyzed. 展开更多
关键词 underwater acoustic channel orthogonal frequency division multiplexing (OFDM) underwateracoustic communication frequency diversity Doppler estimation Doppler compensation
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Soft Direct-Adaptation Based Bidirectional Turbo Equalization for MIMO Underwater Acoustic Communications 被引量:5
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作者 Junyi Xi Shefeng Yan +1 位作者 Lijun Xu Jing Tian 《China Communications》 SCIE CSCD 2017年第7期172-183,共12页
This paper proposes a soft direct-adaptation based bidirectional turbo equalizer for multiple-input multiple-output underwater acoustic communication systems. Soft, rather than hard, direct-adaptation based equalizer ... This paper proposes a soft direct-adaptation based bidirectional turbo equalizer for multiple-input multiple-output underwater acoustic communication systems. Soft, rather than hard, direct-adaptation based equalizer combined with the fast self-optimized least mean square algorithm is employed to achieve a faster convergence rate, and the second-order phase-locked loop is embedded into the equalizer to track the time-varying channel. Meanwhile, by utilizing a weighted linear combining scheme, the conventional soft direct-adaptation based equalizer is combined with the time-reversed soft direct-adaptation based equalizer to exploit bidirectional diversity and mitigate error propagation. Both the simulation and experimental results demonstrate that the soft direct-adaptation based bidirectional turbo equalizer outperforms the single-direction soft direct-adaptation based turbo equalizer, and achieves a faster convergence rate than the hard direct-adaptation based bidirectional turbo equalizer. 展开更多
关键词 soft direct-adaptation based turbo equalizer bidirectional turbo equalizer multipie-input multiple-output underwater acoustic communications
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Immune particle swarm optimization of linear frequency modulation in acoustic communication 被引量:4
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作者 Haipeng Ren Yang Zhao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第3期450-456,共7页
With the exploration of the ocean, underwater acoustic communication has attracted more and more attention in recent years. The underwater acoustic channel is considered to be one of the most complicated channels beca... With the exploration of the ocean, underwater acoustic communication has attracted more and more attention in recent years. The underwater acoustic channel is considered to be one of the most complicated channels because it suffers from more serious multipath effect, fewer available bandwidths and quite complex noise. Since the signals experience a serious distortion after being transmitted through the underwater acoustic channel, the underwater acoustic communication experiences a high bit error rate (BER). To solve this problem, carrier waveform inter- displacement (CWlD) modulation is proposed. It has been proved that CWlD modulation is an effective method to decrease BER. The linear frequency modulation (LFM) carrier-waves are used in CWlD modulation. The performance of the communication using CWID modulation is sensitive to the change of the frequency band of LFM carrier-waves. The immune particle swarm optimization (IPSO) is introduced to search for the optimal frequency band of the LFM carrier-waves, due to its excellent performance in solving complicated optimization problems. The multi-objective and multi- peak optimization nature of the IPSO gives a suitable description of the relationship between the upper band and the lower band of the LFM carrier-waves. Simulations verify the improved perfor- mance and effectiveness of the optimization method. 展开更多
关键词 underwater acoustic communication carrier waveform inter-displacement (CWlD) multi-objective optimization immune particle swarm optimization (IPSO).
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Cross-Ice Acoustic Communication:Cascade Acoustic Channel Model and Experimental Results 被引量:2
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作者 Jingwei Yin Wei Men +1 位作者 Guangping Zhu Xiao Han 《China Communications》 SCIE CSCD 2021年第2期228-240,共13页
Cross-ice acoustic information transmission is an effective means of communication in polar sea areas covered by ice.However,the channel is extremely complicated because of the combined influence of water,ice,and air.... Cross-ice acoustic information transmission is an effective means of communication in polar sea areas covered by ice.However,the channel is extremely complicated because of the combined influence of water,ice,and air.Based on the normalmode theory,this paper establishes a cascade acoustic channel(CAC)model for the transmission of underwater acoustic waves across ice layer.The model can calculate the displacement response of the ice layer’s upper surface by separating the upward waves from normal modes in the water and multiplying it by a transmission coefficient matrix.The relationship between the displacement response of the upper surface of ice layer and the acoustic frequency is calculated by the finite-element method,and the calculation result was consistent with that of the CAC model.To verify the applicability of the model,a cross-ice acoustic communication experiment was conducted in Songhua River in January 2019.Experimental results show the energy of the acoustic signals received by geophones is closely related to sound frequency and crossice acoustic communication is feasible.The result of present research is important for understanding crossice acoustic channel characteristics and developing future cross-ice acoustic communication in polar sea areas. 展开更多
关键词 cross-ice acoustic communication normal mode CAC model transmission coefficient
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MIMO Underwater Acoustic Communication in Shallow Water with Ice Cover 被引量:1
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作者 HAN Xiao YIN Jing-wei +1 位作者 LIU Bing GUO Long-xiang 《China Ocean Engineering》 SCIE EI CSCD 2019年第2期237-244,共8页
Although multiple-input multiple-output(MIMO) underwater acoustic(UWA) communication has been intensively investigated in the past years, existing works mainly focus on open-water environment. There is no work reporti... Although multiple-input multiple-output(MIMO) underwater acoustic(UWA) communication has been intensively investigated in the past years, existing works mainly focus on open-water environment. There is no work reporting MIMO acoustic communication in under-ice environment. This paper presents results from a recent MIMO acoustic communication experiment which was conducted in Bohai Gulf during winter. In this experiment, high frequency MIMO signals centered at 10 kHz were transmitted from a two-element source array to a four-element vertical receiving array at 1 km range. According to the received signal of different array elements, MIMO acoustic communication in under-ice environment suffers less effect from co-channel interference compared with that in open-water environment. In this paper, time reversal followed by a single channel decision feedback equalizer is used to process the experimental data. It is demonstrated that this simple receiver is capable of realizing robust performance using fewer hydrophones(i.e. 2) without the explicit use of complex co-channel interference cancelation algorithms, such as parallel interference cancelation or serial interference cancelation. 展开更多
关键词 UNDERWATER acoustic communication MIMO SHALLOW water ICE COVER
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Feedback strategies for iterative channel estimation in OFDM underwater acoustic communications 被引量:2
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作者 Zhu Anfu Li Xue 《High Technology Letters》 EI CAS 2018年第4期396-401,共6页
The extremely limited bandwidth in underwater acoustic communication makes channel estimation using fewer pilot symbols more challenging. Iterative channel estimation( ICE) can be used to refine channel estimation wit... The extremely limited bandwidth in underwater acoustic communication makes channel estimation using fewer pilot symbols more challenging. Iterative channel estimation( ICE) can be used to refine channel estimation with limited number of pilots,by coupling the channel estimator with channel decoder. In this paper,various feedback strategies in ICE are discussed. The performance of a decision feedback based on the cost function is improved by modifying the design and another four feedback strategies are summarized,including hard/soft decision feedback and their threshold-controlled versions. Simulation results show that ICE can achieve impressive gains over the non-iterative receiver and the gains are more significant with fewer pilots. Furthermore,soft decision feedback outperforms hard decision feedback; while the feedback based on the cost function and soft decision feedback have quite close performance. 展开更多
关键词 UNDERWATER acoustic communication ORTHOGONAL frequency DIVISION multiplexing(OFDM) iterative FEEDBACK sparse channel estimation
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Power optimization algorithm for OFDM underwater acoustic communication using adaptive channel estimation 被引量:1
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作者 LUO Yasong HU Shengliang +1 位作者 FENG Chengxu TONG Jijin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2019年第4期662-671,共10页
An adaptive channel estimation algorithm for the channel length is proposed to construct a channel estimation model suitable for orthogonal frequency division multiplexing(OFDM)underwater acoustic communication signal... An adaptive channel estimation algorithm for the channel length is proposed to construct a channel estimation model suitable for orthogonal frequency division multiplexing(OFDM)underwater acoustic communication signals for the dependence of traditional channel estimation algorithms on channel length information.This algorithm can be adopted to evaluate channel estimation quality in real time and to adaptively adjust the channel length of the channel estimation algorithm according to the evaluation result,which satisfies the need of accurate estimation of unknown underwater acoustic channels and communication application;based on the study on the relationship between the OFDM communication bit error rate and the subcarrier signal to noise ratio,a self-adjusting optimization scheme for OFDM subcarrier transmitting power is proposed,which realizes underwater communication with the low bit error rate through higher energy efficiency.The validity of the research content is verified through simulation and field experiments. 展开更多
关键词 CHANNEL estimation UNDERWATER acoustic communication ORTHOGONAL frequency divisionmultiplexing(OFDM) adaptive
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LDPC Coded DQPSK Modulation with Iterative Detection Method for Underwater Acoustic Communications 被引量:1
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作者 Fang Fu Rui Xue +1 位作者 Dan-Feng Zhao Xiang-Chao Zhou 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2013年第5期25-30,共6页
Aimed at the conventional serial communication system fails when the channel was frequency-selective,long delay and multi-paths effect,resulting in inter-symbol-interference( ISI),an iterative system for underwater ac... Aimed at the conventional serial communication system fails when the channel was frequency-selective,long delay and multi-paths effect,resulting in inter-symbol-interference( ISI),an iterative system for underwater acoustic communication( UWAC) was proposed,which employed iterative differential detection and spread spectrum technique. The proposed scheme adopts π /4-DQPSK soft demodulation to overcome the difficulty of phase ambiguity. For suppression of ISI in UWAC,joint demodulation and decoding iteration was used. The communication scheme has the characteristic of long communication range at low SNR,and the maximum range is up to 100 km. The theoretic analysis and simulation results show that the proposed scheme outperforms traditional serial one. When SNR is- 6 dB,after four joint iterations,compared with serial scheme,BER can decrease from 10- 2to 10- 5. 展开更多
关键词 UNDERWATER acoustic communicationS joint DEMODULATION and DECODING ITERATIVE differential DECODING SPREAD spectrum
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Acoustic MIMO Communications in a Very Shallow Water Channel 被引量:1
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作者 Yuehai Zhou Xiuling Cao Feng Tong 《Journal of Marine Science and Application》 CSCD 2015年第4期434-439,共6页
Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multipl... Underwater acoustic channels pose a great difficulty for the development of high speed communication due to highly limited band-width as well as hostile multipath interference. Enlightened by rapid progress of multiple-input multiple-output (MIMO) technologies in wireless communication scenarios, MIMO systems offer a potential solution by enabling multiple spatially parallel communication channels to improve communication performance as well as capacity. For MIMO acoustic communications, deep sea channels offer substantial spatial diversity among multiple channels that can be exploited to address simultaneous multipath and co-channel interference. At the same time, there are increasing requirements for high speed underwater communication in very shallow water area (for example, a depth less than 10 m). In this paper, a space-time multichannel adaptive receiver consisting of multiple decision feedback equalizers (DFE) is adopted as the receiver for a very shallow water MIMO acoustic communication system. The performance of multichannel DFE receivers with relatively small number of receiving elements are analyzed and compared with that of the multichannel time reversal receiver to evaluate the impact of limited spatial diversity on multi-channel equalization and time reversal processing. The results of sea trials in a very shallow water channel are presented to demonstrate the feasibility of very shallow water MIMO acoustic communication. 展开更多
关键词 underwater acoustic underwater acoustic communication multiple-input multiple-output (MIMO) decision feedback equalizer (DFE) very shallow water MULTI-CHANNEL time reversal
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An improved least mean square/fourth direct adaptive equalizer for under-water acoustic communications in the Arctic 被引量:1
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作者 Yanan Tian Xiao Han +2 位作者 Jingwei Yin Hongxia Chen Qingyu Liu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2020年第9期133-139,共7页
An improved least mean square/fourth direct adaptive equalizer(LMS/F-DAE)is proposed in this paper for underwater acoustic communication in the Arctic.It is able to process complex-valued baseband signals and has bett... An improved least mean square/fourth direct adaptive equalizer(LMS/F-DAE)is proposed in this paper for underwater acoustic communication in the Arctic.It is able to process complex-valued baseband signals and has better equalization performance than LMS.Considering the sparsity feature of equalizer tap coefficients,an adaptive norm(AN)is incorporated into the cost function which is utilized as a sparse regularization.The norm constraint changes adaptively according to the amplitude of each coefficient.For small-scale coefficients,the sparse constraint exists to accelerate the convergence speed.For large-scale coefficients,it disappears to ensure smaller equalization error.The performance of the proposed AN-LMS/F-DAE is verified by the experimental data from the 9th Chinese National Arctic Research Expedition.The results show that compared with the standard LMS/F-DAE,AN-LMS/F-DAE can promote the sparse level of the equalizer and achieve better performance. 展开更多
关键词 underwater acoustic communication the Arctic direct adaptive equalizer adaptive norm
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Coevolution of acoustical communication between obligate avian brood parasites and their hosts 被引量:1
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作者 Jiaojiao Wang Qihong Li Canchao Yang 《Avian Research》 CSCD 2020年第4期367-379,共13页
The mutually antagonistic processes producing adaptations and counter-adaptations in avian brood parasites and their hosts provide a model system for the study of coevolution;this topic has long been an area of focus ... The mutually antagonistic processes producing adaptations and counter-adaptations in avian brood parasites and their hosts provide a model system for the study of coevolution;this topic has long been an area of focus in ornithology and evolutionary biology.Although there is an extensive body of literature dealing with avian brood parasitism,few empirical studies have considered the effects of the coevolutionary processes associated with brood parasitism on the acoustic characteristics of parent–offspring communication.Under the strong selection pressures associated with brood parasitism,parasitic birds may,for instance,produce deceptive songs.The host may in turn evolve the ability to recognize these sounds as deceptive.At present,the mechanisms underlying the different competitive strategies employed by hosts and parasitic birds remain unclear.Here,we reviewed previous studies that investigated acoustic traits in scenarios of brood parasitism,highlighting possible adaptive functions.Using a meta-analysis,we identified no heterogeneity among studies of begging call adaptations in parasitic nestlings.However,our results may have been affected by the small number of applicable papers available for analysis.Our meta-analysis also suggested that studies of acoustic communication and transmission in adult hosts were highly heterogenous,suggesting that research methods were inconsistent among studies.Finally,we identified knowledge gaps and proposed several lines of future research. 展开更多
关键词 acoustic communication Brood parasitism Coevolution Parasitic adaptations Anti-parasitic adaptations
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Null subcarriers based Doppler scale estimation with polynomial interpolation for multicarrier communication over ultrawideband underwater acoustic channels 被引量:1
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作者 Yang Chen Jingwei Yin +2 位作者 Ling Zou Dan Yang Yuan Cao 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2015年第6期1177-1183,共7页
This paper addresses the extremal problem of the null subcarriers based Doppler scale estimation in underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) communication. The cost function cons... This paper addresses the extremal problem of the null subcarriers based Doppler scale estimation in underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) communication. The cost function constructed of the total energy of null subcarriers through discrete Fourier transform (DFT) is proposed. The frequencies of null subcarriers are identified from non-uniform Doppler shift at each tentative scaling factor. Then it is proved that the cost function can be fitted as a quadratic polynomial near the global minimum. An accurate Doppler scale estimation is achieved by the location of the global scarifying precision and increasing the computation minimum through polynomial interpolation, without complexity. A shallow water experiment is conducted to demonstrate the performance of the proposed method. Excellent performance results are obtained in ultrawideband UWA channels with a relative bandwidth of 67%, when the transmitter and the receiver are moving at a relative speed of 5 kn, which validates the proposed method. 展开更多
关键词 underwater acoustic (UWA) communication orthogo-nal frequency division multiplexing (OFDM) Doppler scale estimation polynomial interpolation.
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RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication 被引量:7
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作者 WANG Zhongqiu WANG Hongru MENG Qingming 《Instrumentation》 2015年第2期47-54,共8页
RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In s... RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication. 展开更多
关键词 recursive least squares least mean square method multi-user detection blind adaptive acoustic communication
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Novel joint encoding/decoding algorithms of fountain codes for underwater acoustic communication 被引量:1
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作者 Mingshen Liang Jinjue Duan +2 位作者 Danfeng Zhao Jiaxi Si Xiangyu Song 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2016年第4期772-779,共8页
Fountain codes are considered to be a promising coding technique in underwater acoustic communication(UAC) which is challenged with the unique propagation features of the underwater acoustic channel and the harsh ma... Fountain codes are considered to be a promising coding technique in underwater acoustic communication(UAC) which is challenged with the unique propagation features of the underwater acoustic channel and the harsh marine environment. And Luby transform(LT) codes are the first codes fully realizing the digital fountain concept. However, in conventional LT encoding/decoding algorithms, due to the imperfect coverage(IC) of input symbols and short cycles in the generator matrix, stopping sets would occur and terminate the decoding. Thus, the recovery probability is reduced,high coding overhead is required and decoding delay is increased.These issues would be disadvantages while applying LT codes in underwater acoustic communication. Aimed at solving those issues, novel encoding/decoding algorithms are proposed. First,a doping and non-uniform selecting(DNS) encoding algorithm is proposed to solve the IC and the generation of short cycles problems. And this can reduce the probability of stopping sets occur during decoding. Second, a hybrid on the fly Gaussian elimination and belief propagation(OFG-BP) decoding algorithm is designed to reduce the decoding delay and efficiently utilize the information of stopping sets. Comparisons via Monte Carlo simulation confirm that the proposed schemes could achieve better overall decoding performances in comparison with conventional schemes. 展开更多
关键词 underwater acoustic communication(UAC) fountain codes non-uniform encoding hybrid decoding algorithm stopping sets
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Acoustic wireless communication based on parameter modulation and complex Lorenz chaotic systems with complex parameters and parametric attractors
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作者 Fang-Fang Zhang Rui Gao Jian Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第8期248-259,共12页
As the competition for marine resources is increasingly fierce,the security of underwater acoustic communication has attracted a great deal of attention.The information and location of the communicating platform can b... As the competition for marine resources is increasingly fierce,the security of underwater acoustic communication has attracted a great deal of attention.The information and location of the communicating platform can be leaked during the traditional underwater acoustic communication technology.According to the unique advantages of chaos communication,we put forward a novel communication scheme using complex parameter modulation and the complex Lorenz system.Firstly,we design a feedback controller and parameter update laws in a complex-variable form with rigorous mathematical proofs(while many previous references on the real-variable form were only special cases in which the imaginary part was zero),which can be realized in practical engineering;then we design a new communication scheme employing parameter modulation.The main parameter spaces of the complex Lorenz system are discussed,then they are adopted in our communication scheme.We also find that there exist parametric attractors in the complex Lorenz system.We make numerical simulations in two channels for digital signals and the simulations verify our conclusions. 展开更多
关键词 parameter modulation identification chaotic system acoustic wireless communication
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Modeling and Channel Estimation for Piezo-Acoustic Backscatter Assisted Underwater Acoustic Communications
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作者 Junliang Lin Gongpu Wang +3 位作者 Zijian Zheng Ruyi Ye Ruisi He Bo Ai 《China Communications》 SCIE CSCD 2022年第11期297-307,共11页
Relying on direct and converse piezoelectric effects,piezo-acoustic backscatter(PAB)technology reflects ambient acoustic signals to enable underwater backscatter communications at near-zero power,which was first reali... Relying on direct and converse piezoelectric effects,piezo-acoustic backscatter(PAB)technology reflects ambient acoustic signals to enable underwater backscatter communications at near-zero power,which was first realized through a prototype.In this paper,we propose a mathematical model of the PAB assisted underwater acoustic(UWA)communication,and address the sparse channel estimation problem.First,we present a five-stage backscatter process to derive the backscatter coefficient,and propose the channel model for the shallow-water communications.Then,we formulate the shallow-water acoustic channel estimation problem as a sparse vector recovery one according to the compressed sensing theory,and leverage the orthogonal matching pursuit(OMP)algorithm to obtain the channel estimator.Finally,simulation results are provided to corroborate our proposed studies. 展开更多
关键词 channel estimation compressed sensing piezo-acoustic backscatter underwater acoustic communications
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Channel Estimation and Compensation for Underwater Acoustic Pipeline Communication
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作者 Weijiang Wang Nan Su Jianyan Liu 《Journal of Beijing Institute of Technology》 EI CAS 2017年第2期252-258,共7页
An estimation and compensation algorithm for underwater acoustic pipeline channel is investigated.A joint time-frequency adaptive signal-to-noise ratio(SNR)estimation based on the maximum likelihood method is introd... An estimation and compensation algorithm for underwater acoustic pipeline channel is investigated.A joint time-frequency adaptive signal-to-noise ratio(SNR)estimation based on the maximum likelihood method is introduced firstly,and the Cramer-Rao lower bound(CRLB)is proposed so as to evaluate the performance of the SNR estimation algorithm.For frequency-selective fading channel part,estimation and compensation are made to improve the robustness of the system on the basis of the LMS algorithm.Furthermore,real-time update iteration algorithm in the frequency domain is investigated to realize synchronous receiving and estimation.For verification,simulations and actual data tests were made,and the results show that the algorithm possesses great robustness,efficiency and accuracy inrealization of SNR estimation,signal detection and frequency impulse compensation for the channel. 展开更多
关键词 acoustic pipeline communication signal-to-noise ratio (SNR) estimation channel estimation COMPENSATION
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Beam alignments based on the spectrum decomposition of orbital angular momentums for acoustic-vortex communications
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作者 Gepu Guo Xinjia Li +4 位作者 Qingdong Wang Yuzhi Li Qingyu Ma Juan Tu Dong Zhang 《Chinese Physics B》 SCIE EI CAS CSCD 2022年第12期296-304,共9页
Given the enhanced channel capacity of wave chirality,acoustic communications based on the orbital angular momentum(OAM)of acoustic-vortex(AV)beams are of significant interest for underwater data transmissions.However... Given the enhanced channel capacity of wave chirality,acoustic communications based on the orbital angular momentum(OAM)of acoustic-vortex(AV)beams are of significant interest for underwater data transmissions.However,the stringent beam alignment is required for the coaxial arrangement of transceiver arrays to ensure the accuracy and reliability of OAM decoding.To avoid the required multiple measurements of the traditional orthogonality based algorithm,the beam alignment algorithm based on the OAM spectrum decomposition is proposed for AV communications by using simplified ring-arrays.Numerical studies of the single-OAM and OAM-multiplexed AV beams show that the error of the OAM spectrum increases with the translation distance and the deflection angle of the transceiver arrays.To achieve an ideal arrangement,two methods of the single-array translation alignment and the dual-array deflection alignment are developed based on the least standard deviation of the OAM spectrum(SD-OAM).By decreasing the SD-OAM towards zero using transceiver arrays of 16 transmitters and 16 receivers,accurate beam alignments are accomplished by multiple adjustments in three dimensions.The proposed method is also demonstrated by experimental measurements of the OAM dispersion and the SD-OAM for misaligned beams.The results demonstrate the feasibility of the rapid beam alignment based on the OAM spectrum decomposition by using simplified transceiver ring-arrays,and suggest more application potentials for acoustic communications. 展开更多
关键词 acoustic-vortex beam beam alignment orbital angular momentum(OAM)spectrum least standard deviation acoustic communication
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