Channel model for wideband time-varying underwater acoustic systems

In this paper a wideband underwater acoustic (UWA) channel simulator is developed based on the geometry of the system deployment and by considering the statistics of the random amplitude variation of the channel. This channel simulator is capable of modeling any relative motion between the transmitter and receiver. The delays of multipath arrivals are calculated based on the geometrical and physical parameters of the deployment. The time-varying fractional delay line (TVFDL) is utilized as a flexible and low-complexity software tool to model time-scaling observed on individual paths. The fading characteristics of the channel which is extracted from the measurements is utilized to model the time-varying amplitudes of paths. Also, an orthogonal frequency division multiplexing (OFDM) system is tested throughout a sea trial. The geometrical and statistical parameters of the sea trial are utilized to test the OFDM system using the proposed channel simulator. The bit error rate (BER) of the system is calculated in both measurements and simulations and it will be shown that the assessment of the communication performance realized using simulations is very close to that of the measured performance.