Usage of Turbo Coding to Improve the Performance of Underwater Telecommunication Systems Based on Adaptive OFDM Modulation

The most important limitations for wireless underwater telecommunication systems are multipath, fading, attenuation, and extensive interference in underwater channels. In these channels, due to wide changes in the signal-to-noise ratio, transmitting and receiving in fixed modulation mode does not have the desired performance. For this reason, in this paper, the use of turbo coding to encode an adaptive modulation system based on orthogonal frequency division multiplexing (OFDM) is introduced for the first time, which reduces the transmission error and also achieves high efficiency. In the proposed system model, the optimal system was achieved by selecting appropriate parameters for communication in the underwater acoustic environment and also choosing proper modulation modes, which decreases the bit error rate by 16% compared to other systems introduced so far for underwater acoustic communication