Abstarct: Underwater is one of the most challenging wireless data transmission environments. In this environment, due to the strong absorption of electromagnetic waves, magnetic induction and optical waves, acoustic signals are used for data transmission. Multiple paths and high latency, bandwidth and frequency selectivity limitations, high time variability, and high doppler effects are among the most important environmental degradation parameters that can be identified for underwater acoustic channels. In order to establish a connection with high reliability and acceptable rates in these types of channels, multicarrier systems, due to their good performance against multipath and the ability to cope with fading with frequency selector and high spectrum returns, are a good candidate for data transfer. Due to the bandwidth limitation and the long and time-varying impact response of the underwater channel, the use of the traditional CP-OFDM system due to the use of a long random cyclic prefix outside the DFT range results in a sharp decrease in bandwidth in the underwater channel. In this regard, we use the new transfer technique among other methods baxsed on OFDM called UW-OFDM, for transmitting data under the channel for the first time. In this new technique, a unique word (UW) and non-random is used within the DFT range as a protective laxyer, which leads to a shorter length of the received symbol on the channel and simplifies the process of estimating and synchronizing. In 2017, another OFDM-baxsed transfer technique called OTFS modulation, is actually a family of multicarrier systems baxsed on bank filters, is proposed to counteract the high temporal variability of wireless communications channels. In this technique, the information symbols experience a slower channel scatter and flexibility, along with nearly constant channel gain in the Delta-Doppler domain. Due to the multipath characteristics and the time variation of the underwater channel, in this thesis, for the first time, we use this technique to transfer data in underwater telecommunication channels, and compare it with the function of the conventional OFDM technique. In order to achieve the above objectives, in this thesis, subcontinental acoustic channel characteristics are introduced first and a discrete-time TDL model is introduced to simulate a shallow water channel, then the CP-OFDM method for sending and receiving data in This channel is introduced and simulated. In the following, each of the new techniques is introduced and after explanation and simulation, the performance of each one in the shallow water channel is investigated and evaluated in terms of the probability of error in comparison with the CP-OFDM method