Delay-Doppler Domain Channel Measurements and Modeling in High-Speed Railways

2025-09-30

AI Summary

Existing Delay-Doppler (DD) domain channel modeling theory is inadequate for high-frequency, high-mobility scenarios—particularly high-speed railway (HSR) communications—where conventional time-varying assumptions fail to capture rapid channel dynamics. Method: This paper proposes a novel DD-domain channel measurement and modeling framework tailored for HSR. It introduces the quasi-stationary interval as the fundamental criterion for DD-domain model construction, revealing that fading coefficients remain approximately invariant at the millisecond scale—challenging the traditional assumption of variation over hundreds of milliseconds. Leveraging real-world LTE-R measurements at 371 km/h, the method integrates statistical power modeling, quasi-stationary analysis, and OTFS bit-error-rate validation to precisely characterize DD-domain temporal dynamics. Contribution/Results: The resulting model adapts flexibly to varying channel time-selectivity conditions. Both simulations and field measurements demonstrate substantial improvements in modeling accuracy and transmission performance for DD-domain modulation schemes, especially OTFS.

Technology Category

• Application Domains: Mobility, Driving & Flight
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Transfer, Domain Adaptation, Multi-Task Learning

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Vertical and domain-specific search

Abstract

As next-generation wireless communication systems need to be able to operate in high-frequency bands and high-mobility scenarios, delay-Doppler (DD) domain multicarrier (DDMC) modulation schemes, such as orthogonal time frequency space (OTFS), demonstrate superior reliability over orthogonal frequency division multiplexing (OFDM). Accurate DD domain channel modeling is essential for DDMC system design. However, since traditional channel modeling approaches are mainly confined to time, frequency, and space domains, the principles of DD domain channel modeling remain poorly studied. To address this issue, we propose a systematic DD domain channel measurement and modeling methodology in high-speed railway (HSR) scenarios. First, we design a DD domain channel measurement method based on the long-term evolution for railway (LTE-R) system. Second, for DD domain channel modeling, we investigate quasi-stationary interval, statistical power modeling of multipath components, and particularly, the quasi-invariant intervals of DD domain channel fading coefficients. Third, via LTE-R measurements at 371 km/h, taking the quasi-stationary interval as the decision criterion, we establish DD domain channel models under different channel time-varying conditions in HSR scenarios. Fourth, the accuracy of proposed DD domain channel models is validated via bit error rate comparison of OTFS transmission. In addition, simulation verifies that in HSR scenario, the quasi-invariant interval of DD domain channel fading coefficient is on millisecond (ms) order of magnitude, which is much smaller than the quasi-stationary interval length on $100$ ms order of magnitude. This study could provide theoretical guidance for DD domain modeling in high-mobility environments, supporting future DDMC and integrated sensing and communication designs for 6G and beyond.

Problem

• Modeling delay-Doppler domain channels for high-speed railway communications
• Addressing poor study of DD domain principles in high-mobility scenarios
• Establishing accurate channel models using quasi-stationary interval criteria

Innovation

• Proposed delay-Doppler domain channel measurement methodology
• Established channel models under varying time-varying conditions
• Validated models via OTFS transmission bit error rate