Grid Evolution Based on Cluster Fusion for Doubly Fractional Channel Estimation in OTFS Systems

In orthogonal time-frequency space communications, the performance of the uniform grid channel estimation (CE) is generally determined by the delay-Doppler (DD) grid density. A finer grid interval is needed to reduce modeling errors, but this could result in a significantly higher CE complexity when traditional methods are used. Although the grid evolution (GE) method can achieve a good trade-off between complexity and CE performance, there are still many redundant DD grid points that incur additional computational complexity. To address this issue, a new GE method based on cluster fusion for doubly fractional CE is proposed. Simulation results show that our proposed method leads to improved computational efficiency, and achieves a good trade-off between CE performance and complexity.