HYDROACOUSTICS
ANNUAL JOURNAL
START NEW VOL 19 SEARCH STATISTICS PAS - GDANSK DIVISION

OFDM modulation and adaptive equalization for underwater communications

pp. 77-82, vol. 8, 2005

Iwona Kochańska
Gdańsk University of Technology, Faculty of Electronic Engineering, Telecommunications and Computer Science, Department of Marine Electronic Systems, Gdańsk, Poland

Henryk Lasota
Gdańsk University of Technology, Faculty of Electronic Engineering, Telecommunications and Computer Science, Department of Marine Electronic Systems, Gdańsk, Poland

Roman Salamon
Gdańsk University of Technology, Faculty of Electronic Engineering, Telecommunications and Computer Science, Department of Marine Electronic Systems, Gdańsk, Poland

Key words:

Abstract: Transmission performances of a shallow underwater channel are limited due to multiple reflections of sound waves off the bottom and water surface, and to the non-stationarity caused mainly by water surface movement. In traditional narrowband telecommunication modems complex Decision Feedback Equalizers are used for minimizing the influence of intersymbol interferences caused by multipath propagation of sound waves. The article proposes adapting OFDM modulation and adaptive equalization based on Kalman filtration techniques for use in underwater communications system. The OFDM modulation is used in wideband ADSL telecommunication modems. The Kalman filtration algorithm is used for time-varying processes identification. The techniques were tested in simulation environment with promising results.

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