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.

翻译：随着下一代无线通信系统需要能够在高频段和高移动性场景下运行，时延-多普勒（DD）域多载波（DDMC）调制方案（如正交时频空间（OTFS）调制）相比正交频分复用（OFDM）展现出更优越的可靠性。精确的DD域信道建模对于DDMC系统设计至关重要。然而，由于传统信道建模方法主要局限于时域、频域和空域，DD域信道建模的原理仍缺乏深入研究。针对这一问题，我们提出了一种高速铁路（HSR）场景下系统化的DD域信道测量与建模方法。首先，基于铁路长期演进（LTE-R）系统设计了一种DD域信道测量方法。其次，针对DD域信道建模，研究了准平稳区间、多径分量统计功率建模，特别地，研究了DD域信道衰落系数的准不变区间。第三，通过以371 km/h速度进行的LTE-R测量，以准平稳区间作为判定准则，建立了HSR场景下不同信道时变条件下的DD域信道模型。第四，通过OTFS传输的误码率比较验证了所提DD域信道模型的准确性。此外，仿真验证了在HSR场景中，DD域信道衰落系数的准不变区间处于毫秒（ms）量级，远小于准平稳区间长度的百毫秒量级。本研究可为高移动性环境下的DD域建模提供理论指导，支撑面向6G及未来通信的DDMC与通感一体化设计。