Effect of wind-generated bubbles on OFDM power loading for time-varying shallow water acoustic channels with limited feedback

Wind blowing over the sea surface generates many dramatic effects. One of the most important effects is bubbles generated by breaking waves, which has major effects on high frequency acoustic propagation, sound speed profile and ambient noise due to the sound scattering and absorption properties of a thin layer of bubbles. In this paper, on one hand, we analyze several important properties of bubbles and their effects on acoustic propagation and sound speed profile; on the other hand, we propose an optimization model aiming at maximizing system capacity with the constraint of the total transmission power in a symbol. It is achieved by adopting the Lloyd algorithm based limited feedback procedure. Simulation results reveal underwater acoustic (UWA) channel impulse responses both with and without the effect of bubbles, and the limited feedback based system capacities comparison in terms of obtained channel impulse responses will be demonstrated.