Low-Complexity Biconjugate Gradient Stabilized-Based Receiver for ZP-OTFS

Orthogonal Time Frequency Space (OTFS) modulation is considered a promising waveform candidate for 6G communications due to its excellent bit error rate (BER) performance in high-mobility scenarios. In this letter, a low-complexity receiver for zero-padded OTFS (ZP-OTFS) systems is proposed, utilizing the Biconjugate Gradient Stabilized (BiCGSTAB) method. The receiver first extracts the effective portion of the time-domain channel block matrix corresponding to the transmitted signals, thereby maintaining the per-iteration computational complexity at a level comparable to that of soft-estimation maximal ratio combining (SE-MRC). After a straightforward preprocessing step, the BiCGSTAB method is applied for iterative detection to effectively suppress error propagation. Furthermore, the proposed receiver is fully compatible with Turbo iterative structures. Simulation results demonstrate that, compared to MRC, the proposed receiver achieves similar BER performance while significantly reducing computational complexity.