In this paper, for the purpose of investigating horizontal sound propagation, based on the results obtained from practical measurements in the Strait of Hormoz and available data on sound speed variations at different depths, a comprehensive model for shallow water multipath underwater acoustic channel is presented. Mathematical modeling of multipath effect is based on ray theory and the image method. In channel modeling, attenuation due to wave scatterings at the surface and bottom reflections is considered. In addition, we also consider attenuations due to the absorption of sound by different materials and the presence of ambient noises such as the sea state noise, shipping noise, thermal noise and turbulence noise. Then, complete underwater communication system consisting transmitter, channel and receiver was simulated. We use QPSK modulation. Data is transmitted at a rate of 5 kbit/sec with a carrier frequency of 27 kHz, for a maximum range of 1km. The channel estimation is based on a training sequence which occupies about 10% of the signal bit rate.