Orthogonal Filtered Delay-Doppler Multiplexing (OF2DM) With Enhanced Robustness to Doppler and Timing Offsets

Abstract

This paper proposes a novel transceiver structure built on a newly designed waveform in this work, termed Orthogonal Filtered Delay-Doppler Multiplexing (OF2DM), targeting the challenges of next-generation wireless systems. Unlike existing modulation schemes, OF2DM ensures real-domain orthogonality in the time-frequency domain through a dedicated two-dimensional Hermitian-symmetric precoding structure. An efficient associated receiver is also developed based on the Overlap-Save algorithm. The proposed system achieves strong robustness to Doppler spread and timing offsets, and excellent spectral confinement. Simulations conducted over the realistic 5G TDL-B QuaDRiGa channel and the ITU-T vehicular A channel model demonstrate that the OF2DM transceiver outperforms both orthogonal time frequency space (OTFS) modulation and orthogonal frequency division multiplexing (OFDM) when considering low complexity minimum mean square error (MMSE) equalizers. These results are further confirmed by an analytical derivation characterizing the interference behavior of the proposed waveform. With its integrated design and superior performance under real-world impairments, OF2DM emerges as a strong candidate for robust, asynchronous, and spectrally efficient wireless communications in future network deployments.