Semantic-Enhanced Downlink LEO Satellite Communication System With OTFS Modulation

As an important technology for achieving 6G global access, low Earth orbit satellite (LEO-Sat) communication still encounters the challenges of scarce spectrum resources and the serious Doppler effect. To improve the performance of image transmission in the LEO-Sat system, this paper proposes an approach that combines semantic communication with orthogonal time-frequency space (OTFS) modulation to effectively mitigate the severe Doppler effect and enhance transmission efficiency. The NTN-TDL-D model in 3GPP is employed to simulate satellite channels and introduce noise into the training process of the semantic model. The performance of semantic-enhanced and traditional LEO-Sat systems is further evaluated under various conditions. Ultimately, simulation results demonstrate that the proposed solution achieves a minimum 6dB signal-to-noise ratio gain, reduces communication overhead by 50%, and ensures higher spectrum utilization efficiency in high-speed scenarios compared to existing solutions.