A broadband UWA communication system: based on COFDM modulation

Lam, W.K.; Ormondroyd, R.F.

doi:10.1109/oceans.1997.624107

Cited by 9 publications

(4 citation statements)

References 15 publications

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“…Moreover, redundancy across carriers employing coding achieves robust performance. The UWAC systems relying on OFDM codes were researched theoretically in several publications [39][40][41][42]. However, experimental results for any of these systems are not available.…”

Section: Uwac Physical Layer Techniquesmentioning

confidence: 99%

A Survey on Physical Layer Techniques and Challenges in Underwater Communication Systems

Junejo

Sattar

Adnan

et al. 2023

JMSE

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In the past decades, researchers/scientists have paid attention to the physical layer of underwater communications (UWCs) due to a variety of scientific, military, and civil tasks completed beneath water. This includes numerous activities critical for communication, such as survey and monitoring of oceans, rescue, and response to disasters under the sea. Till the end of the last decade, many review articles addressing the history and survey of UWC have been published which were mostly focused on underwater sensor networks (UWSN), routing protocols, and underwater optical communication (UWOC). This paper provides an overview of underwater acoustic (UWA) physical layer techniques including cyclic prefix orthogonal frequency division multiplexing (CP-OFDM), zero padding orthogonal frequency division multiplexing (ZP-OFDM), time-domain synchronization orthogonal frequency division multiplexing (TDS-OFDM), multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM), generalized frequency division multiplexing (GFDM), unfiltered orthogonal frequency division multiplexing (UF-OFDM), continuous phase modulation orthogonal frequency division multiplexing (CPM-OFDM), filter bank multicarrier (FBMC) modulation, MIMO, spatial modulation technologies (SMTs), and orthogonal frequency division multiplexing index modulation (OFDM-IM). Additionally, this paper provides a comprehensive review of UWA channel modeling problems and challenges, such as transmission loss, propagation delay, signal-to-noise ratio (SNR) and distance, multipath effect, ambient noise effect, delay spread, Doppler effect modeling, Doppler shift estimation. Further, modern technologies of the physical layer of UWC have been discussed. This study also discusses the different modulation technology in terms of spectral efficiency, computational complexity, date rate, bit error rate (BER), and energy efficiency along with their merits and demerits.

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Section: Uwac Physical Layer Techniquesmentioning

confidence: 99%

A Survey on Physical Layer Techniques and Challenges in Underwater Communication Systems

Junejo

Sattar

Adnan

et al. 2023

JMSE

View full text Add to dashboard Cite

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“…Note that this packet could be modulated not only in OFDM, but in any other format, as long as its spectral content is sufficiently rich. The issue of probe design for underwater channel estimation and OFDM symbol synchronization is considered in [6], where a pseudo-random Gaussian noise (PRGN) sequence is proposed as an optimal OFDM sounding waveform with nearly constant spectral envelope across the desired bandwidth and extremely low sidelobe levels.…”

Section: Ofdm Modulationmentioning

confidence: 99%

“…Coherent multicarrier modulation, on the other hand, has received scarce attention [6,7], which contrasts sharply with the large body of work on this subject in wireline and wireless radio communications, where orthogonal frequency-division multiplexing (OFDM) is one of the preferred ways of approaching capacity in frequency-selective channels. This discrepancy may be due to the perception that most off-vertical underwater channels are too complex and dynamic for the subtle orthogonality of carriers to be ensured reliably.…”

Section: Introductionmentioning

confidence: 99%

Time-reversed OFDM communication in underwater channels

Gomes

Barroso

IEEE 5th Workshop on Signal Processing Advances in Wireless Communications, 2004.

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-Time reversal is a feedback wave focusing technique that can be used to transparently compensate for multipath distortion in digital communications over several types of physical propagation media, such as radio or acoustic channels. While much of the work on this topic has focused on coherent communication through single-carrier modulation, time reversal can in fact be applied to any signaling scheme. This paper discusses issues related to protocol design and data modulation/demodulation when multicarrier signals are used, with an emphasis on underwater communication. It is shown that focusing information can be derived at the transmitter array by prefiltering a single observed broadband channel probe, thus streamlining the design of communication protocols. Conventional prefix-based demodulation can be achieved for sufficiently well focused OFDM signals, but this may be somewhat demanding in terms of transmitter hardware. A receiver architecture based on multipleinput/multiple-output decision-feedback equalization is proposed when few transmit elements are used, creating significant residual intersymbol interference.

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“…When coupled with channel coding, OFDM has the potential to achieve reliable communications in challenging channels. Several schemes based on coded OFDM have been suggested for the underwater channel [6] [7]. However, we are not aware of any experimental results from the use of OFDM schemes in very shallow water channels and non-Gaussian noise.…”

Section: Introductionmentioning

confidence: 99%

Performance of coded OFDM in very shallow water channels and snapping shrimp noise

Ong¹,

Potter²

Proceedings of OCEANS 2005 MTS/IEEE

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-Although acoustic energy has been used effectively for point-to-point communications in deepwater channels, it has had limited success for horizontal transmissions in shallow water. Time-varying multipath propagation and non-Gaussian snapping shrimp noise are two of the major factors that limit acoustic communication performance in shallow water. Rapid time variation in the channel can limit the use of equalizers to compensate for frequency selective fading introduced due to multipath propagation. OFDM (orthogonal frequency division multiplexing), a communication technique widely used in wired and wireless systems, divides the available bandwidth across a number of smaller carriers, each of which experiences flat fading. This simplifies the equalizer structure and provides robustness against time-varying frequencyselective fading. Another source of signal degradation is impulsive noise from snapping shrimp, which affects several OFDM carriers at the same time. OFDM, when coupled with coding, can provide robustness against impulsive noise by distributing the energy for each bit over a longer period of time. We tested coded OFDM in a very shallow water channel in Singapore waters. The results show that it is a promising technique for use in very shallow, warm water channels.

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A broadband UWA communication system: based on COFDM modulation

Cited by 9 publications

References 15 publications

A Survey on Physical Layer Techniques and Challenges in Underwater Communication Systems

A Survey on Physical Layer Techniques and Challenges in Underwater Communication Systems

Time-reversed OFDM communication in underwater channels

Performance of coded OFDM in very shallow water channels and snapping shrimp noise

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