Efficient Image Transmission in UWA Channel

In the quest for exploration of minerals and other resources, remote real time underwater water monitoring is gaining huge popularity. Remote monitoring of underwater expedition can be efficiently monitored from above the surface by transmission and reception of high quality images and videos. However such transmission or reception for underwater application, is extremely difficult as the communication has to be via highly lossy underwater acoustics (UWA) channel. The traditionally used orthogonal frequency-division multiplexing (OFDM) scheme for UWA communication is very lossy and the quality of the final received images or videos get highly degraded. The present work proposes a system based on 2D modulation scheme of orthogonal time frequency & space (OTFS) for image transmission through UWA channels. OTFS is designed by taking the best of time division multiplexing (TDM) and frequency division multiplexing (FDM) techniques. This work proves that combining OTFS waves and UWA waves, a high resolution image can be prepared for transmission. The proposed scheme can be easily extended to the cases of video transmission. In the proposed system, all the delay-Doppler diversity branches are combined in a coherent manner. The high resolution delay-Doppler separation enables OTFS to attain channel capacity with optimal performance-complexity. The proposed model gives robustness against Doppler effect and multipath channel conditions. The advantage of the proposed model over the traditionally used OFDM has been established by intensive simulation and are presented here.