A Cross-Domain Iterative OTFS Receiver for Sparse Doubly Selective Channels

A cross-domain iterative receiver structure is proposed for orthogonal time frequency space (OTFS) systems over sparse doubly selective channels. It achieves higher reliability by alternatively performing channel estimation and signal detection across time-frequency (TF) domain and delay-Doppler (DD) domain. In particular, with the aid of some hybrid pilots designed carefully, TF-domain channel estimation enables higher accuracy than the existing DD-domain channel estimation schemes, thanks to less interference from the data symbols in TF domain. Low-complexity data detection is performed in DD domain to exploit the full diversity of OTFS. Furthermore, the detected data is removed from the received signal to further eliminate interference and enhance channel estimation. Simulation results demonstrate that the proposed cross-domain iterative OTFS receiver outperforms the existing schemes in terms of mean square error of channel estimation and bit error rate, with less pilot overhead.