A journey toward modeling and resolving doppler in underwater acoustic communications

Qu, Fengzhong; Wang, Zhenduo; Yang, Liuqing; Wu, Zhizhou

doi:10.1109/mcom.2016.7402260

Cited by 77 publications

(40 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The definitions of variables in (A1) are the same as in (4). In addition, we assume that the channel has L paths, with {A l , a l , τ l } as the path amplitude, Doppler scale factor and time delay of the lth path.…”

Section: Uwamentioning

confidence: 99%

“…In underwater communications, acoustic waves propagate at 1500 m/s, much lower than the speed of electromagnetic waves in terrestrial wireless systems (which is 3 × 10 8 m/s). Thus, the motion of platform will cause more significant Doppler effects, which is expressed as signal compressing or dilating in time domain and can be treated as Doppler scale [4]. In addition, the delay spread results in severe inter-symbol interference (ISI) [5].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Novel Approach for the Estimation of Doubly Spread Acoustic Channels Based on Wavelet Transform

Zhang

Song

et al. 2018

Applied Sciences

View full text Add to dashboard Cite

Abstract:In this paper, the estimation of doubly spread underwater acoustic (UWA) channels is investigated. The UWA channels are characterized by severe delay spread and significant Doppler effects, and can be well modeled as a multi-scale multi-lag (MSML) channel. Furthermore, exploiting the sparsity of UWA channels, MSML channel estimation can be transformed into the estimation of parameter sets (amplitude, Doppler scale factor, time delay). Based on this, the orthogonal matching pursuit (OMP) algorithm has been widely used. However, the estimation accuracy of OMP depends on the size of the dictionary, which is related with both delay spread and Doppler spread. Thus it requires high computational complexity. This paper proposes a new method, called wavelet transform (WT) based algorithm, for the UWA channel estimation. Different from OMP algorithm which needs to search in both time domain and Doppler domain, WT-based algorithm only needs to search in time domain by using the Doppler invariant characteristic of hyperbolic frequency modulation (HFM) signal. The performance of the proposed algorithm is evaluated by computer simulations based on BELLHOP. The simulation results show that WT-based algorithm performs slightly better than OMP algorithm in low signal to noise ratio (SNR) while can greatly reduce computational complexity.

show abstract

Section: Uwamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Novel Approach for the Estimation of Doubly Spread Acoustic Channels Based on Wavelet Transform

Zhang

Song

et al. 2018

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…As a UWAS channel has time-varying characteristics, the multi-band communication technology [6][7][8], which allocates the same data to different frequency bands, has been recently highlighted because it As a UWAS channel has time-varying characteristics, the multi-band communication technology [6][7][8], which allocates the same data to different frequency bands, has been recently highlighted because it overcomes the frequency-selective fading that occurs due to the underwater multi-path and the Doppler spread [9][10][11]. In other words, the multi-band communication technology overcomes various problems of underwater channel environments and extends the propagation distances, thereby, improving both the performance and the propagation efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…Experimental results showed that the performance increased as the number of multiple bands increased. Furthermore, the performance of multi-band was improved when the proposed threshold algorithm was applied.overcomes the frequency-selective fading that occurs due to the underwater multi-path and the Doppler spread [9][10][11]. In other words, the multi-band communication technology overcomes various problems of underwater channel environments and extends the propagation distances, thereby, improving both the performance and the propagation efficiency.…”

mentioning

confidence: 99%

A Weighted Turbo Equalized Multi-Band Underwater Wireless Acoustic Communications

et al. 2018

View full text Add to dashboard Cite

The multi-band UWAS (Underwater Wireless Acoustic Sensor) communication techniques are effective in terms of performance and throughput efficiency because they can overcome selective frequency fading by allocating the same data to different frequency bands, in an environment of rapidly changing channel transfer characteristic. However, the multi-band configuration may have a performance worse than the single-band one because performance degradation in one particular band affects the output from all the other bands. This problem can be solved by using a receiving end that analyzes the error rates of each band, sets threshold values and allocates the lower weights to the inferior bands. There are many methods of setting threshold values. In this paper, we proposed an algorithm to set the threshold value by using the preamble error rates, which are known data that have to be transmitted and received. In addition, we have analyzed the efficiency of multi-band transmission scheme in the UWAS communication by applying 1~4 number of multi-bands, using turbo pi codes, with a coding rate of 1/3. We evaluated the performance of the proposed multi-bands transmission model in real underwater environments. Experimental results showed that the performance increased as the number of multiple bands increased. Furthermore, the performance of multi-band was improved when the proposed threshold algorithm was applied.overcomes the frequency-selective fading that occurs due to the underwater multi-path and the Doppler spread [9][10][11]. In other words, the multi-band communication technology overcomes various problems of underwater channel environments and extends the propagation distances, thereby, improving both the performance and the propagation efficiency. However, as long-distance communications use a narrow frequency band, the multi-band communication is based on a limited range of available frequencies. For military submarine applications, UWAS systems are required to remain undetected, be highly reliable, and require long-range communication. The goal of the multi-band underwater communication is to successfully transmit data in various underwater channel environments and extended propagation distances.The research project of EUROPA "UUV Covert Acoustic Communications" tested, at a sea trial, using eight sub-bands with turbo coding techniques, at a data rate of 75 bps, had a range of up to 50 km [12]. In the multi-band transmission and reception structure of the reference [12], the turbo coded 5670 bits of each band and the preamble 2880 bits were divided into 45 and then the divided preamble bits and coded bits were sequentially arranged to form a single packet, which was iteratively propagated to each band. However, the multi-band configuration may have worse performance than the single-band one. It is because the performance degradation in a particular band affects the output from the entire bands, which is input into an encoder, thereby decreasing the overall performance. This problem can be solved through a receiving e...

show abstract

“…However, the item 3) sometimes plays an important role in the field of digital television (TV) broadcasting and point-tomulti point (P-MP) communication systems [3], [4]. Furthermore, underwater acoustic communications (UWAC) have been recently investigated by several researchers [5], [6]. For acoustic communication systems, the item 3) is required in addition to the items 1) and 2).…”

Section: Introductionmentioning

confidence: 99%

Differential MIMO Spatial Multiplexing Employing PADM Based on Channel Prediction for Fast Time-Varying Channels

Mori

Takuma

Akinobu

et al. 2017

Journal of Signal Processing

View full text Add to dashboard Cite

This paper proposes a demodulation scheme based on channel prediction for differential multiple-input multipleoutput (MIMO) spatial multiplexing employing per-transmit antenna differential mapping (PADM). As PADM is one of the differential space-time trellis codings (DSTTCs), it requires per-survivor processing (PSP) based on the Viterbi algorithm (VA) for its demodulation. Therefore, PADM has excellent tracking performance on fast time-varying channels. However, aiming at higher frequency efficiency, PADM for a higher modulation index suffers from the following two disadvantages: (1) poor receiver sensitivity; (2) high computational complexity. In order to solve the items (1) and (2), this paper employs a spatial multiplexing structure and a state reduction algorithm for the VA, i.e., decision-feedback sequence estimation (DFSE), respectively. Finally, for a frequency efficiency of 4bps/Hz with two receive antennas, computer simulation results confirm that the proposed scheme has excellent bit error rate (BER) performance on fast time-varying channels in the case of the maximum Doppler frequency normalized by a symbol rate of 4%.

show abstract

A journey toward modeling and resolving doppler in underwater acoustic communications

Cited by 77 publications

References 8 publications

A Novel Approach for the Estimation of Doubly Spread Acoustic Channels Based on Wavelet Transform

A Novel Approach for the Estimation of Doubly Spread Acoustic Channels Based on Wavelet Transform

A Weighted Turbo Equalized Multi-Band Underwater Wireless Acoustic Communications

Differential MIMO Spatial Multiplexing Employing PADM Based on Channel Prediction for Fast Time-Varying Channels

Contact Info

Product

Resources

About