Time-reversed OFDM communication in underwater channels

Gomes, Jorge; Barroso, V.

doi:10.1109/spawc.2004.1439321

Cited by 21 publications

(11 citation statements)

References 12 publications

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“…[32][33] proposed two time-reversal applications in multi-channel/OFDM UWA communications. [34][35] proposed two time-reversal applications in MIMO communications in shallow water environments.…”

Section: Challenging Issues Of Time-reversal Communicationsmentioning

confidence: 99%

Time Reversal in Underwater Acoustic Communications

Li¹,

Papson²

2012

IJCA

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How to achieve high data rate coherent underwater acoustic (UWA) communications is a challenging topic due to several unique properties of UWA environments, especially in shallow water acoustic environments. Time reversal, or phase conjugation in the frequency domain, is a process engages in achieving high data rate and reliable high frequency coherent communications in time-varying UWA environments, while reducing the system complexity significantly compared with traditional methods, such as using large arrays of sensors, or redundantly transmitting at different time. Therefore, timereversal technique has been approved to be a promising technique in future UWA communications and networks. In his paper, we will present an overview of the application of the time-reversal process to acoustic communications. The content includes basic concept and mechanism of timereversal in UWA communications, passive and active timereversal UWA communications, application challenges of the time-reversal technique in UWA communications and networks. General TermsWireless communication and signal processing

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Section: Challenging Issues Of Time-reversal Communicationsmentioning

confidence: 99%

Time Reversal in Underwater Acoustic Communications

Li¹,

Papson²

2012

IJCA

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“…Throughput in underwater channels is hampered not just by the limited bandwidth of the acoustic signal, but also the multipath propagation effects, the resulting high frequency selectivity, reverberation generated by various scatterers (suspended in the volume and from the bottom) and also by the ambient ocean noise [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Channel estimation and BER studies for an underwater acoustic OFDM system using time reversal mirror in shallow waters

Vadde

Indushree

Sequeira

2011

2011 International Symposium on Ocean Electronics

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Underwater acoustic communication in shallow-waters could greatly benefit from using multicarrier communication with time-reversal mirror as a signal-focusing tool. The advantages of combining OFDM with TRM for telemetry are investigated from a channel perspective. A channel estimation algorithm specially designed for TRM-OFDM is presented. Bit error rate characteristics and channel-usage efficiency are studied in a TRM-OFDM context. Link-level simulations for a Pekeris channel, using OFDM modulation with TRM signaling for various channel-types are presented as bit error rate (BER) results. TRM with OFDM is shown to improve system BER by a factor of 5 as compared to an OFDM system without TRM.

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“…Channel conditions such as these are more likely to be encountered in practice than the short responses reported in [3,4,5]. Passive time reversal is used as a computationally inexpensive preprocessing scheme to shorten the effective channel length to less than 10 ms, so that moderate guard intervals can be used with a conventional OFDM receiver architecture [6].…”

Section: Introductionmentioning

confidence: 99%

Experimental assessment of time-reversed OFDM underwater communications

Gomes

Silva

Jesus

2008

The Journal of the Acoustical Society of America

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OFDM communication has recently been demonstrated in underwater channels at rates of 10 − 30 kbps. This is a popular modulation in radio communications due to its spectral flexibility and the simplicity of FFT-based transmitters/receivers. Despite widespread interest, experimental data on the performance of underwater OFDM are still scarce. This work aims to contribute to a better understanding of the potential of this technique by examining results from the UAB'07 experiment, which was conducted in Norway, in September 2007. Modulated data were transmitted in a fjord using several formats with bandwidths of 1.5 and 4.5 kHz, and recorded at a range of about 800 m in a 16-hydrophone array. Significant multipath was observed over a period of at least 30 ms, which would call for a large OFDM prefix and hence drastically reduce the data rate. Passive time reversal is used here as a computationally inexpensive preprocessing scheme to shorten the effective channel length to less than 10 ms, so that moderate guard intervals can be used with a conventional OFDM receiver architecture. The same marker signals used for packet synchronization and Doppler compensation are reused as channel probes for passive time reversal, so the latter entails no loss in efficiency.

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Time-reversed OFDM communication in underwater channels

Cited by 21 publications

References 12 publications

Time Reversal in Underwater Acoustic Communications

Time Reversal in Underwater Acoustic Communications

Channel estimation and BER studies for an underwater acoustic OFDM system using time reversal mirror in shallow waters

Experimental assessment of time-reversed OFDM underwater communications

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