WITHDRAWN: A comparative study of impacts multipath propagation channel using empirical models

Abstract

Tigris river is a shallow water environment due to its low depth and is characterized as a multi-path channel. Underwater multipath propagation causes reverberation and fading, resulting in a large loss of transmission. This research compared two underwater acoustic simulation results in Abu Dali district, Kazem Al Ali village, Tigris beaches, Baghdad, Iraq and Al-Atifiyah district, Iraq. The distance between the sender and the receiver is (100 m and 1000 m). With the use Ray model, the results show that multipath propagation becomes worse in the case of Al-Atifiyah district compared with the case Abu Dali district due to the lower wind speed leads to the surface reflection coefficient (R s ) will increase. Besides, depending on the type of bottom (Bt), the bottom reflection coefficient (R b ) will increase in the case of fine sand compared with the case in very fine sand. Moreover, multipath propagation dominates when the distance between the sender and receiver increased, leading to the grazing angle (φ) decreased, thus increasing the coefficient of reflection. The amplitude of the successive paths will not decrease rapidly. As a result, the difference in time between the various paths is minimal. This means that successive paths will converge over time lead to the phenomenon of inter symbol interference (ISI), which contributes to an increment in the bit error rate of the received data.