Parameter study of OFDM underwater communications system

Design criteria and analysis procedures for a practical OFDM underwater communications system are presented. A new broadband underwater channel model with Doppler time scaling effect is developed. A two-dimensional MMSE scheme using time and frequency pilots is employed for channel estimation. Doppler frequency shift is estimated using cyclic prefix and is compensated by a digital sampling rate conversion procedure. Numerical simulations demonstrate that the OFDM technique is robust with respect to frequency selectivity and time selectivity.