Detection Techniques for OTFS Transmissions Over Doubly Selective Channels

In this paper, we focus on orthogonal time frequency space (OTFS) modulated transmissions over doubly-selective channels. Specifically, we investigate the state-of-the-art techniques for effective detection in high-mobility scenarios and introduce innovative strategies aimed at achieving an optimal trade-off between complexity and performance. The proposed solutions are based on the Ungerboeck observation model and exploit the structure of the resulting channel matrix in the Doppler-delay domain. In particular, the first proposed method, denoted as HBCJRG, belongs to the family of message-passing algorithms, whose strength lies in a scheduling scheme that prioritizes the strongest interferers during the detection process. In contrast, the second proposed approach, denoted as ICG, is based on interference cancellation. Differently from the HBCJRGapproach, whose required computational load grows quadratically with the constellation cardinality, the ICGalgorithm is characterized by extremely low complexity. Simulation results demonstrate that the latter strategy allows to achieve an optimal trade-off between complexity and performance when compared to existing state-of-the-art solutions.