Equalizer Mode Selection Method for Improving Bit Error Performance of Underwater Acoustic Communication Systems

Abstract

ABSTRACT:The linear and decision-feedback equalization can mitigate time-varying intersymbol interference (ISI) caused by time-varying multipath propagation for underwater acoustic channels. The perfect elimination of interference components, however, is difficult using the linear equalization and the decision feedback equalizer has an error propagation problem. To overcome these shortcomings, this paper proposes an equalizer mode selection method using training sequences. The proposed method selects an equalization mode corresponding to the signal-to-noise ratio (SNR). If the SNR is low, the proposed system operates the linear equalizer for preventing the error propagation and if the SNR is high, the decision feedback equalizer for eliminating the residual ISI. Therefore, the proposed method can improve the error performance compared to the conventional equalizers. The computer simulation shows the proposed method improves the bit error performance using practical underwater channels responses acquired from the sea experiment.

Performance Evaluation of Underwater Acoustic Communication in Frequency Selective Shallow Water

“…[1][2][3][4] Special emphasis on the BER has been given to the effect of time-varying signal fluctuation due to sea surface roughness, which results in severe degradation of system performance by causing time and frequency spread of the transmitted signal. This is the fact that multipath time spread between the first and the last arrival path may span very much long comparing to bit interval and leads to severe Inter-Symbol Interference (ISI).…”