Millimeter-wave and terahertz systems rely on beamforming/combining codebooks to determine the best beam directions during the initial access and data transmission. Existing approaches suffer from large codebook sizes and high beam searching overhead in the presence of mobile devices. To address this issue, we utilize the similarity of the channel in adjacent locations to divide the user trajectory into a set of separate regions and maintain a set of candidate beams for each region in a database. Due to the tradeoff between the number of regions and the signalling overhead, i.e., the greater number of regions results in a higher signal-to-noise ratio (SNR) but also a larger signalling overhead for the database, we propose an optimization framework to find the minimum number of regions based on the trajectory of a mobile device. Using a ray tracing tool, we demonstrate that the proposed method provides high SNR while being more robust to the location information accuracy in comparison to the lookup table baseline and fixed size region baseline.

翻译：毫米波与太赫兹系统在初始接入及数据传输阶段依赖波束赋形/合并码本确定最佳波束方向。现有方法在移动设备场景下面临码本规模大、波束搜索开销高的难题。针对该问题，我们利用相邻位置信道的相似性将用户轨迹划分为若干独立区域，并在数据库中为各区域维护候选波束集合。由于区域数量与信令开销存在权衡关系——即区域数量越多可获得更高的信噪比，但数据库信令开销也越大——我们提出一种优化框架，基于移动设备轨迹求解最小区域数量。通过射线追踪工具验证表明，相较于查表基线方法与固定区域大小基线方法，所提方法在提供高信噪比的同时，对位置信息精度具有更强的鲁棒性。