## 1 Introduction
Although transmitter antenna diversity methods are particularly convenient for base stations of cellular systems, they are not very suitable for mobile terminals in terms of size, cost and hardware complexity. In addition, the powerful shadowing effect caused by crowded vehicles and buildings can especially lead to serious performance loss in V2V and V2X communications. As a solution to this problem, the \"cooperative diversity or cooperative communication\" technique has been used. In cooperative communication, the source-transmitter provides transmitter diversity by sending its information directly to the destination-receiver through one or more cooperators (relays) [9]. Cooperative communication technology achieves cooperative diversity through relays, which can cope with the impact of shadowing effect and improve communication reliability. In this way, the effect of a less costly MIMO system with high efficiency is achieved [2]. One of the cooperative diversity methods in which users can act as relays is the \"amplify and forward (AF)\" method. It is a cooperative communication method first proposed by the authors of [10]. In accordance with this method, the other cooperating user amplifies and transmits the signal coming from the source user. Another method, the \"decode and forward (DF)\" method, was first proposed by the authors of [11]. In accordance with this scenario, the other cooperative user decodes the signal coming from the source user and transmits it digitally again. Another method, \"coded cooperation\", was first proposed by the authors of [12]. In accordance with this proposed method, the signal coming from the source user is re-encoded by another auxiliary user and sent to the destination. In the \"selection relaying\" method mentioned in [13], the focus is on the amplifier gain, which depends on the fading coefficient between the source and the relay. If the measured gain is below a specific threshold, the source goes on its transmission to the destination. If the measured gain is above the threshold, the relay transmits using AF or DF to achieve diversity gain. In [14], the relay remains silent when the S-R link is in outage and assists only when the mutual information involving the relay self-interference is greater than R bit/s/Hz, i.e., when the outage does not occur. Previous works such as [15; 16] have emphasized the performance degradation of terminal mobility on cooperative communication. On the other hand, this problem can be reduced by exploiting the robustness of OTFS in cooperative communication [2; 17; 18; 19; 20; 21]. For example, in the study [2], the proposed cooperative OTFS system with AF and DF protocols achieved gains of approximately 15.1 dB and 12.0 dB, respectively, compared to the non-cooperative OTFS system. The proposed cooperative OTFS system beats the traditional non-cooperative OTFS system as better diversity gains and end-to-end SNR can be obtained with the help of relaying. In [17], the authors express that the natural robustness of OTFS can mitigate the presence of the node mobility problem in collaborative communications. Therefore, they present an analysis of the end-to-end performance of MIMO-OTFS in decode-and-forward (DaF) cooperative systems. In [18], the authors highlight making cooperative communication an attractive model to overcome the restrictions of conventional point-to-point OTFS systems. In this context, they present an end-to-end performance analysis of OTFS index modulation in the DaF cooperative system. In [20], it is stated that OFDM systems put limitations such as sensitivity to the Doppler effect in high-speed mobile conditions. To solve this problem, OTFS-assisted cooperative transmission (CT) for UAV swarms is proposed, which can overcome the above-mentioned limitations. In the study [21], the presence of cooperative UAV transmitting jamming signals using OTFS modulation was shown to enhance the security of the legitimate LEO SatCom link.