Analysis of Acoustic Channel Characteristics in Shallow Water Based on Multipath Model

In the shallow water environment, the water surface, and the seafloor act as reflective boundaries for the sound waves. When a sound wave encounters these boundaries, it undergoes reflection, bouncing back and forth between the surface and the bottom. As a result, the sound energy is distributed among various paths, leading to multipath arrivals at the receiver. The repeated reflections contribute to the complexity of the sound propagation in shallow water. This multipath propagation can cause interference and fading, making the received signals challenging to decode, interpret accurately, and transmission losses. Therefore, proper modelling of channel is essential inoreder to deploy a network with high accuracy. In this work, we have developed and analyzed an acoustic multipath channel model to investigate the impact of mixed layer depth and near field anomaly on transmission losses in underwater environments. The main focus is on understanding how various underwater medium parameters, such as temperature, salinity, depth, and pH, affect the transmission losses. It is evident from simulation results; acoustic velocity has increased by 30 m/s when the temperature reduced from 30 ℃ to 14 ℃ and 7 m/s when the salinity increased from 30 ppt to 35 ppt. Transmission losses are increased by 58.8% when the mixed layer depth (MLD) increased from 10 m to 95 m. Whereas, these losses are reduced by 43.7% when the near field anomaly (KL) increased from 7 dB to 20 dB.