Cross-Domain Division Multiplexing (XDM): Toward Near Interference-Free Coexistence Between OTFS and OFDM

TY - JOUR

T1 - Cross-Domain Division Multiplexing (XDM)

T2 - Toward Near Interference-Free Coexistence Between OTFS and OFDM

AU - Xiang, Yiyue

AU - Ye, Neng

AU - Hou, Xiaolin

AU - Mumtaz, Shahid

N1 - Publisher Copyright: © 1983-2012 IEEE.

PY - 2026

Y1 - 2026

N2 - Coexistence design that enables the emerging candidate waveforms to interoperate with legacy orthogonal frequency division multiplexing (OFDM) is essential for sixth-generation standardization. This paper focuses on orthogonal time frequency space (OTFS)—a representative waveform for high-mobility scenarios—and proposes a novel coexistence paradigm between OTFS and OFDM, termed cross-domain division multiplexing (XDM), utilizing the different signal representations across multiple domains. XDM is formulated through sparse mapping in the delay-Doppler domain and periodicity-based partial superposition in the time-frequency domain. We prove that XDM holds several favorable invariant properties, which enable tractable interference characterization and suppression even under dynamic channels. We also show that XDM supports flexible numerologies and provide some standardization-oriented practice examples. For practical implementation, XDM transceivers are designed for near interference-free coexistence leveraging the invariant properties. We first develop a cross-domain waveform-level interference cancellation algorithm with ultra-low complexity for single OTFS user coexisting with OFDM. More generally, a domain-transform embedded factor-graph is constructed for multiple OTFS users, over which a cross-domain expectation propagation algorithm is proposed to achieve almost lossless recovery of the coexisting signals. Through a novel variance transfer technique, we prove that the detection errors of coexisted OTFS and OFDM respectively converge to their counterparts under interference-free transmission. Simulations show that XDM exhibits BER loss about \mathbf {0.5} dB compared to interference-free transmission under various channel conditions and system configurations.

AB - Coexistence design that enables the emerging candidate waveforms to interoperate with legacy orthogonal frequency division multiplexing (OFDM) is essential for sixth-generation standardization. This paper focuses on orthogonal time frequency space (OTFS)—a representative waveform for high-mobility scenarios—and proposes a novel coexistence paradigm between OTFS and OFDM, termed cross-domain division multiplexing (XDM), utilizing the different signal representations across multiple domains. XDM is formulated through sparse mapping in the delay-Doppler domain and periodicity-based partial superposition in the time-frequency domain. We prove that XDM holds several favorable invariant properties, which enable tractable interference characterization and suppression even under dynamic channels. We also show that XDM supports flexible numerologies and provide some standardization-oriented practice examples. For practical implementation, XDM transceivers are designed for near interference-free coexistence leveraging the invariant properties. We first develop a cross-domain waveform-level interference cancellation algorithm with ultra-low complexity for single OTFS user coexisting with OFDM. More generally, a domain-transform embedded factor-graph is constructed for multiple OTFS users, over which a cross-domain expectation propagation algorithm is proposed to achieve almost lossless recovery of the coexisting signals. Through a novel variance transfer technique, we prove that the detection errors of coexisted OTFS and OFDM respectively converge to their counterparts under interference-free transmission. Simulations show that XDM exhibits BER loss about \mathbf {0.5} dB compared to interference-free transmission under various channel conditions and system configurations.

KW - Coexistence

KW - OFDM

KW - OTFS

KW - factor-graph

KW - interference suppression

UR - https://www.scopus.com/pages/publications/105027677642

U2 - 10.1109/JSAC.2026.3653356

DO - 10.1109/JSAC.2026.3653356

M3 - Article

AN - SCOPUS:105027677642

SN - 0733-8716

VL - 44

SP - 3268

EP - 3284

JO - IEEE Journal on Selected Areas in Communications

JF - IEEE Journal on Selected Areas in Communications

ER -