Modeling of Doppler Power Spectrum for Underwater Acoustic Channels

In this paper, we propose a closed-form expression of Doppler power spectrum model for underwater acoustic (UWA) channels. Using the geometry model for shallow UWA channels, we analyze the theoretical background of Doppler effects generated by the transmitter/receiver (Tx/Rx) movement, or by the motion of sea-surface. As a result, the Doppler power spectrum can be modeled as a summation of the Spike-shape and the Gaussian-shape. The Spike-shape presents the Doppler component from the Tx/Rx movement, while the Gaussian-shape presents the Doppler component from the sea-surface motion. The proposed model is validated through curve fitting with the Doppler power spectrum measurement results of a real shallow UWA channel in Halong bay, Vietnam. The optimal parameters of the proposed model are derived from the measurement results by applying an optimization algorithm called the Lp-norm method. The curve fitting results show that our proposed model matches well with the measurements. Therefore, the proposed Doppler model can accurately describe the Doppler effects for shallow UWA channels. The proposed model can be used to design UWA channel simulators for the performance evaluation of UWA communication systems.