DRIFT: Joint Channel Estimation and Prediction Towards Pilotless 6G Non-Terrestrial Networks
DRIFT:面向无导频6G非地面网络的联合信道估计与预测
Bruno De Filippo, Carla Amatetti, Alessandro Vanelli-Coralli
AI总结 针对6G低轨卫星网络中导频开销大和星载计算受限的问题,提出一种轻量级联合信道估计与预测框架DRIFT,通过仅在初始时隙发送导频并利用数据驱动处理后续时隙,在低计算复杂度下实现高达12%的频谱效率提升。
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非地面网络(NTN)有望通过实现无处不在的连接和大规模通信,在第六代(6G)系统中发挥关键作用。在此背景下,信道预测成为一项关键技术,通过限制导频开销来提高频谱利用效率。然而,许多基于人工智能(AI)的预测器具有高推理复杂度,给星载实现带来挑战。本文针对低地球轨道(LEO)NTN,在严格功率约束限制模型复杂度的情况下,设计了精确且计算高效的信道预测技术,以实现频谱效率增益。我们提出了一种面向6G NTN的迭代联合信道估计与预测框架,通过仅在初始时隙传输导频,并在后续时隙依赖数据驱动处理,显著降低了导频开销。我们引入了DRIFT(无线信道跟踪的数据驱动细化与迭代预测),这是一种轻量级架构,以低计算成本和减少的误差传播来细化数据辅助的信道估计并预测未来的信道频率响应。研究了基于卷积层和长短期记忆层的两种预测器变体。在上行链路LEO NTN场景的端到端仿真中,结果表明,与传统基于导频的系统相比,所提方法实现了高达12%的频谱效率增益,对训练-测试不匹配具有鲁棒性,并在不同信道模型下保持一致的性能。此外,DRIFT所需的乘加运算少于20万次,使其适用于严格功率约束下的星载实现。
Non-terrestrial networks (NTNs) are expected to play a pivotal role in sixth-generation (6G) systems by enabling ubiquitous connectivity and massive communication. In this context, channel prediction emerges as a key technique to improve the spectrum utilization efficiency by limiting the pilot overhead. However, many proposed predictors based on artificial intelligence (AI) are characterized by high inference complexity, posing challenges to onboard implementation. In this paper, we address the challenge of designing accurate yet computationally efficient channel prediction techniques tailored to low Earth orbit (LEO) NTNs, where strict power constraints limit model complexity, to enable spectral efficiency gains. We propose an iterative joint channel estimation and prediction framework in the context of 6G NTNs that significantly reduces pilot overhead by transmitting pilots only in the initial slot and relying on data-driven processing for subsequent slots. We introduce Data-driven Refinement and Iterative Forecast for wireless channel Tracking (DRIFT), a lightweight architecture that refines data-aided channel estimates and predicts future channel frequency responses with low computational cost and reduced error propagation. Two predictor variants based on convolutional and long short-term memory layers are investigated. Simulation results in an end-to-end simulation of an uplink LEO NTN scenario show that the proposed approach achieves up to 12% spectral efficiency gain compared to conventional pilot-based systems, with robustness to training-test mismatches and consistent performance across different channel models. Moreover, DRIFT requires fewer than 200k multiply-accumulate operations, making it suitable for on-board satellite implementation under stringent power constraints.