左世元 范戎飞

摘要：准确及时的信道估计对实现高铁应用场景中的高吞吐量毫米波通信具有重要作用。然而，由于列车高速移动，信道条件变化迅速，频繁测量将带来巨大开销。针对上述问题，利用列车与基站间信道到达角（AoA）与离开角（AoD）经常性连续变化、偶发性骤变的特征，设计AoA与AoD连续变化跟踪与骤变检测算法。在信道AoA与AoD变化符合预期时，基于角度先验信息测量部分信道参数；在AoA与AoD发生骤变时，第一时间报警并通知系统重新测量信道整体参数。设计的收发机波束成形算法可提升AoA与AoD变化跟踪与骤变检测的性能。提出的混合方案可有效降低高速移动条件下的毫米波信道估计信令开销。高速移动对无线信道带来的快衰落影响，并且系统误比特率性能也得到了明显改善。

关键词：高铁；毫米波通信；信道估计

Abstract： Accurate and timely channel estimation plays an important role in realizing highthroughput millimeter wave communication in high-speed railway application scenarios. However， due to the high-speed movement of trains， the channel conditions change rapidly， and frequent measurements will bring huge overhead. Aiming at the above problems， based on the characteristics of frequent continuous changes and occasional sudden changes in the channel of the angle of arrival （AoA） and the angle of departure （AoD） between the train and the base station， the AoA and AoD continuous changes tracking and sudden changes detection algorithms are designed. When the AoA and AoD changes are in line with expectations， some parameters of the channel are measured based on the angle prior information， and when the AoA and AoD change suddenly， they will be alerted and notified to remeasure the overall channel parameters. The transceiver beamforming algorithm is designed to improve the performance of the tracking of AoA and AoD continuous changes and the detection of sudden changes. Through the hybrid scheme， the overhead of millimeter wave channel estimation signaling can be effectively reduced under high-speed mobile conditions.

Keywords： high-speed railway； millimeter wave； channel estimation

高铁是目前中短距離出行的重要交通工具，全程时间短，运送能力大，受气候影响小。在高铁上架载毫米波通信收发机与地面基站建立连接，可发挥大吞吐量的技术优势，为高铁乘客提供高速率无线接入，满足乘客5G时代的通信需求[1-2]。毫米波频段具有高衰减特征，需要精确的信道状态信息（CSI），以生成指向性强波束并实现高吞吐量通信。

毫米波的CSI由收发机间角度信息和每条传播路径的信道系数构成，其中，角度信息包括收发端有限条传播路径的离开角（AoD）和到达角（AoA）。信道估计是指收端通过发端多次发射的导频信号解算CSI。……