In this paper, a reduced-complexity cross-domain iterative detection for orthogonal time frequency space (OTFS) modulation is proposed, which exploits channel properties in both time and delay-Doppler domains. Specifically, we first show that in the time domain effective channel, the path delay only introduces interference among samples in adjacent time slots, while the Doppler becomes a phase term that does not affect the channel sparsity. This ``band-limited'' matrix structure motivates us to apply a reduced-size linear minimum mean square error (LMMSE) filter to eliminate the effect of delay in the time domain, while exploiting the cross-domain iteration for minimizing the effect of Doppler by noticing that the time and Doppler are a pair of Fourier dual. The state (MSE) evolution was derived and compared with bounds to verify the effectiveness of the proposed scheme. Simulation results demonstrate that the proposed scheme achieves almost the same error performance as the optimal detection, but only requires a reduced complexity.

翻译：本文提出了一种针对正交时频空(OTFS)调制的低复杂度跨域迭代检测方法，该方法同时利用时域和时延-多普勒域的信道特性。具体而言，我们首先证明在时域有效信道中，路径时延仅会在相邻时隙的采样点间引入干扰，而多普勒效应则表现为一个不影响信道稀疏性的相位项。这种"带限"矩阵结构促使我们采用降维线性最小均方误差(LMMSE)滤波器来消除时域中的时延影响，同时利用跨域迭代来最小化多普勒效应——注意到时域与多普勒域构成一对傅里叶对偶。推导出状态（均方误差）演化过程并与理论界限进行对比，验证了所提方案的有效性。仿真结果表明，所提方案在几乎不损失误码性能的前提下，实现了与最优检测相近的误差性能，且所需计算复杂度显著降低。