A Novel DT-Domain MRC-Based Method for Joint OTFS Channel Estimation and Signal Detection

To enhance the performance and reduce the computational complexity of joint channel estimation and signal estimation in rich-scattering environments with high-speed mobility, we focus on Orthogonal Time Frequency Space (OTFS) modulation and propose a novel Delay-Time (DT) domain Maximum Ratio Combining (MRC)-based scheme for joint channel estimation and signal detection. In the proposed scheme, we first develop a Domain-Transform Superimposed Pilot Iterative (DTSPI) framework to reduce data-pilot interference. Then, we design a low-complexity DT domain MRC-based algorithm for effective signal detection, which performs domain transformation via the Hadamard product after a rank-factored Minimum Mean Square Error (rMMSE) channel estimation, leading to a significant reduction in computational complexity. Simulation results show that at SNR ≥ 20 dB, the proposed scheme achieves at least 76.53% Bit Error Rate (BER) reduction over the Message Passing (MP)-based detection approach with only 0.66% of its runtime, while incurring merely 7.56% BER degradation versus the MMSE-based detection approach with 1.34% of its required runtime. Our scheme also outperforms the non-MMSE-based approaches by at least 41.3% in BER for SNR ≥ 10 dB, with only a reasonable computational cost.