面向高多普勒场景下非地面网络（NTN）的类双曲频率调制（HFM）随机接入前导设计
An HFM-Inspired Random Access Preamble Design for NTN under High Doppler
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中文总结 AI 辅助
针对NTN高多普勒场景的PRACH设计问题，提出类HFM前导，通过时延-多普勒模糊函数框架与缩放因子码本实现性能提升，仿真显示其检测概率、定时RMSE及旁瓣性能优于ZC等基线方案。
中文摘要 AI 辅助
非地面网络（NTN）是实现6G泛在连接的关键支撑技术，但低轨（LEO）NTN运行中的高轨道速度与长传播距离会引入大多普勒频移和显著的时延不确定性，对新空口（NR）物理随机接入信道（PRACH）设计构成挑战。传统的Zadoff-Chu（ZC）和线性调频（LFM）前导受影响尤为明显，多普勒诱导的模糊性及时延-多普勒耦合会劣化定时估计和前导识别。本文提出一种类双曲频率调制（HFM）的PRACH前导，用于在未补偿或未知多普勒条件下实现鲁棒同步与可靠识别，采用传统匹配滤波接收机检测，使增益能体现前导设计的优势。统一的时延-多普勒模糊函数框架表征了ZC、LFM及类HFM前导的自模糊与互模糊特性，基于缩放因子的码本确保多用户可分性。在NTN信道条件下的仿真结果证实，与ZC和频域叠加LFM基线相比，该方案具有更高的检测概率、更低的定时均方根误差（RMSE），以及更优的峰值旁瓣比和积分旁瓣比。
英文摘要
Non-terrestrial networks (NTNs) are a key enabler of ubiquitous 6G connectivity, but the high orbital velocity and long propagation distances in low-Earth orbit (LEO) NTN operation introduce large Doppler shifts and substantial delay uncertainty that challenge New Radio (NR) physical random access channel (PRACH) design. Conventional Zadoff Chu (ZC) and linear frequency modulated (LFM) preambles are particularly vulnerable, as Doppler induced ambiguity and delay Doppler coupling degrade timing estimation and preamble identification. This paper proposes a hyperbolic frequency modulation (HFM) inspired PRACH preamble for robust synchronization and reliable identification under uncompensated or unknown Doppler, detected with a conventional matched filter receiver so that the gains reflect the preamble design. A unified delay Doppler ambiguity function framework characterizes the self and cross ambiguity behavior of ZC, LFM, and HFM inspired preambles, and a scaling-factor based codebook ensures multi-user separability. Simulation results under NTN channel conditions confirm higher detection probability, lower timing root mean square error (RMSE), and improved peak to sidelobe and integrated sidelobe levels compared with ZC and frequency-domain superposed LFM baselines.
