On the Characterization and Evaluation of Doppler Squint in Wideband ODDM Systems

2025-08-02

AI Summary

In wideband orthogonal delay-Doppler multiplexing (ODDM) systems, Doppler shift effect (DSE) induces additional delay-Doppler (DD) domain dispersion and power leakage, degrading ISAC performance. Method: This work establishes, for the first time, an exact time-varying frequency response model of DSE under both RCP- and ZP-prefixed wideband ODDM architectures; it analytically derives the resulting DD-domain spreading behavior and power leakage patterns via input-output modeling, closed-form analysis, and numerical simulations. Contribution/Results: The proposed framework quantitatively characterizes DD-domain distortion under doubly-spread channels. Results show that DSE significantly exacerbates DD-domain spreading, undermines signal orthogonality, and deteriorates joint sensing and communication performance in ISAC systems. The model and analytical framework provide a theoretical foundation for channel compensation, waveform design, and integrated signal processing in wideband ODDM systems.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Data management and stream processing for Web, mobile and wireless applications
• Security and Privacy: Large-scale security measurements
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

The recently proposed orthogonal delay-Doppler division multiplexing (ODDM) modulation has been demonstrated to enjoy excellent reliability over doubly-dispersive channels. However, most of the prior analysis tends to ignore the interactive dispersion caused by the wideband property of ODDM signal, which possibly leads to performance degradation. To solve this problem, we investigate the input-output relation of ODDM systems considering the wideband effect, which is also known as the Doppler squint effect (DSE) in the literature. The extra delay-Doppler (DD) dispersion caused by the DSE is first explicitly explained by employing the time-variant frequency response of multipath channels. Its characterization is then derived for both reduced cyclic prefix (RCP) and zero padded (ZP)-based wideband ODDM systems, where the extra DD spread and more complicated power leakage outside the peak region are presented theoretically. Numerical results are finally provided to confirm the significance of DSE. The derivations in this paper are beneficial for developing accurate signal processing techniques in ODDM-based integrated sensing and communication systems.

Problem

• Analyzing Doppler squint effect in wideband ODDM systems
• Characterizing extra delay-Doppler dispersion caused by DSE
• Evaluating performance impact on ODDM signal processing techniques

Innovation

• Analyzes wideband ODDM systems with Doppler squint effect
• Derives extra delay-Doppler dispersion for RCP and ZP systems
• Develops accurate signal processing for ODDM-based systems