Iterative Detection for Orthogonal Time Frequency Space Modulation With ADMM

Orthogonal time frequency space (OTFS) modulation, because of its excellent performance in fast time-varying channels, has been proposed as an alternative to orthogonal frequency-division multiplexing modulation in high-mobility scenarios. Time and frequency diversity can be fully exploited in OTFS systems with proper signal detection. However, most existing signal detection algorithms are based on message passing (MP) algorithms, and their signal detection performance rapidly deteriorates when the channel has low sparsity. In this letter, we first model the OTFS signal detection problem as an optimization problem and propose an alternating direction method of multipliers (ADMM)-based algorithm to solve the problem. On this basis, we further propose a modified ADMM-based algorithm by replacing the penalty term to address the performance loss caused by constraint relaxation. The numerical results show that the proposed algorithms are effective in terms of convergence and detection performance.