Channel-Dependent Adaptive Time/Frequency Domain Detection for ODDM

In this work, we investigate computational complexity reduction for the detection of the emerging Orthogonal DelayDoppler Division Multiplexing (ODDM), where existing time domain detection schemes become computationally demanding when the channel delay spread is large. We start by deriving the frequency domain input-output relation for ODDM over general physical channels. Based on this relation, we develop a frequency domain iterative MMSE detection scheme, which effectively reduces detection complexity in channels with large delay spread. To leverage the unique advantages of both time and frequency domain detections, we further propose an adaptive ODDM detection scheme that selects the optimal detection domain based on channel conditions. Simulation results show that our adaptive time/frequency domain detector reduces computational overhead by multiple folds with minimal impact on error performance or power efficiency, compared to conventional non-adaptive detectors under practical system and channel parameters.