Reliable ADMM-Based Signal Detection for OTFS-DCSK Under High-Mobility Scenarios

High-mobility scenarios have increasingly attracted attention due to their relevance in modern wireless communication systems, where doubly selective fading (DSF) significantly degrades transmission reliability. To address this issue, we propose a transceiver that combines orthogonal time frequency space (OTFS) modulation with differential chaos shift keying (DCSK) to provide robustness against DSF. In this design, mapping symbols onto the OTFS delay-Doppler (DD) grid exploits DD diversity, delivering high reliability under DSF and achieving markedly lower bit error rate than conventional schemes. To fully realize these advantages, this paper devises an alternating direction method of multipliers (ADMM)-based signal detection method tailored specifically for OTFS-DCSK. Our solution employs the least squares QR (LSQR) algorithm to leverage channel sparsity, along with truncated singular value decomposition (SVD) to exploit the rank-1 structure of the transmitted symbols, achieving effective noise reduction. Both LSQR and SVD exhibit acceptable complexity, resulting in a computationally efficient detector. Simulation results verify that the developed ADMM algorithm significantly improves reliability, yielding lower normalized mean squared error and bit error rate compared to existing approaches under DSF channels.