arXiv subjects

Kaifeng Bao

Publications and source records attributed to Kaifeng Bao.

3 recordsLinked to original sources

arXiv2026

An OTFS Waveform-Based Delay-Doppler Domain Channel Measurement Method for High-Mobility Scenarios

Channel measurements are the prerequisite for applying emerging transmission technologies and designing communication systems. Conventional time or frequency domain channel measurement methods cannot directly obtain Doppler information induced by high-mobility scenarios. The channel spreading function (CSF) simultaneously captures delay and Doppler information while naturally characterizing the propagation environment in the delay-Doppler (DD) domain. However, DD domain channel measurement methods remain underexplored. This paper presents an orthogonal time frequency space (OTFS) waveform-based DD domain channel measurement method for high-mobility scenarios. A native OTFS waveform, employed as the sounding signal, is designed for the first time, and its sounding capability is comprehensively analyzed. Next, we detail the methodology of DD domain channel measurement, including synchronization and CSF estimation. To enhance measurement precision, a joint fractional delay and Doppler shift estimation algorithm is proposed, and the overall performance of the proposed method is evaluated. Subsequently, a practical DD domain channel measurement system is established, followed by system calibration and verification. Finally, DD domain channel measurements are conducted in vehicle-to-infrastructure (V2I) and vehicle-to-vehicle (V2V) scenarios. Measurement results, including the CSF and other small-scale fading characteristics, confirm the effectiveness of the proposed method and offer valuable insights for advancing research on high-mobility communications.

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arXiv2026

A Novel Deep Learning-Based Coarse-to-Fine Frame Synchronization Method for OTFS Systems

Orthogonal time frequency space (OTFS) modulation is a robust candidate waveform for future wireless systems, particularly in high-mobility scenarios, as it effectively mitigates the impact of rapidly time-varying channels by mapping symbols in the delay-Doppler (DD) domain. However, accurate frame synchronization in OTFS systems remains a challenge due to the performance limitations of conventional algorithms. To address this, we propose a low-complexity synchronization method based on a coarse-to-fine deep residual network (ResNet) architecture. Unlike traditional approaches relying on high-overhead preamble structures, our method exploits the intrinsic periodic features of OTFS pilots in the delay-time (DT) domain to formulate synchronization as a hierarchical classification problem. Specifically, the proposed architecture employs a two-stage strategy to first narrow the search space and then pinpoint the precise symbol timing offset (STO), thereby significantly reducing computational complexity while maintaining high estimation accuracy. We construct a comprehensive simulation dataset incorporating diverse channel models and randomized STO to validate the method. Extensive simulation results demonstrate that the proposed method achieves robust signal start detection and superior accuracy compared to conventional benchmarks, particularly in low signal-to-noise ratio (SNR) regimes and high-mobility scenarios.

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arXiv2025

Ray-Tracing Based Narrow-Beam Channel Simulation, Characterization and Performance Evaluation for 5G-R Systems

This paper investigates narrow-beam channel characterization and performance evaluation for 5G for railway (5G-R) systems based on ray-tracing (RT) simulation. Three representative high-speed railway (HSR) scenarios including viaduct, cutting, and station are established, and RT-based dynamic narrow-beam channel simulations are conducted using a designed beam tracking scheme that ensures continuous alignment with the moving train. The channel characteristics are analyzed in terms of both large-scale and small-scale fading, as well as non-stationarity, providing statistical insights into path loss, shadow fading, fading severity, time-frequency-space dispersion, and stationarity interval. The influence of beamwidth on these channel properties is also examined. Furthermore, the performance of 5G-R systems operating in such narrow-beam channels is evaluated using the Vienna 5G simulator, with a focus on block error rate, throughput, and spectral efficiency. A hardware-in-the-loop simulation platform is developed to further assess synchronization signal reference signal received power, signal-to-interference-plus-noise ratio, and reference signal received quality. The results provide valuable guidance for the design and optimization of 5G-R systems in HSR environments.

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