Evaluation of frequency offset and Doppler effect in terrestrial RF and in underwater acoustic OFDM systems

Abstract

Frequency offset and Doppler effect cause loss of orthogonality in orthogonal frequency division multiplexing (OFDM), which in turn may severely degrade receiver performance. Traditionally, most of the literature dealt with non-varying Doppler effect over OFDM subcarriers. However, in terrestrial ultra-wideband (UWB) OFDM radio frequency (RF) and in high data rate underwater acoustic communication (UAC), the effect of Doppler varies considerably over OFDM band. This paper will investigate the frequency offset and the varying effect of Doppler through analysis and simulation in both domains in order to maintain orthogonality or to compensate loss of orthogonality. To the best knowledge of the authors, this type of detailed analysis is not present in these domains, and thus this paper provides a valuable contribution.