Millimeter-wave and terahertz systems rely on beamforming/combining codebooks for finding the best beam directions during the initial access procedure. Existing approaches suffer from large codebook sizes and high beam searching overhead in the presence of mobile devices. To alleviate this problem, we suggest utilizing the similarity of the channel in adjacent locations to divide the UE trajectory into a set of separate regions and maintain a set of candidate paths for each region in a database. In this paper, we show the tradeoff between the number of regions and the signalling overhead, i.e., higher number of regions corresponds to higher signal-to-noise ratio (SNR) but also higher signalling overhead for the database. We then propose an optimization framework to find the minimum number of regions based on the trajectory of a mobile device. Using realistic ray tracing datasets, we demonstrate that the proposed method reduces the beam searching complexity and latency while providing high SNR.
翻译:为了缓解这一问题,我们建议利用相邻地点的类似通道将UE轨迹分成一组单独的区域,并在数据库中为每个区域保留一套候选路径。我们在本文件中显示了区域数量和信号间接线之间的权衡,即,更多的区域与信号间接线相对应的信号比(SNR)较高,但也提高了数据库的信号间接线。我们随后提出了一个优化框架,以根据移动装置的轨迹找到最低区域数量。我们用现实的射线跟踪数据集,证明拟议的方法在提供高SNR的同时,降低了光束搜索的复杂性和耐久性。