The millimeter wave (mmWave) bands have recently attracted considerable
interest for next-generation cellular systems due to the massive available
bandwidths at these frequencies. However, a key challenge in designing mmWave
cellular systems is initial access -- the procedure by which a mobile
establishes an initial link-layer connection to a base station cell. MmWave
communication relies on highly directional transmissions and the initial access
procedure must thus provide a mechanism by which initial transmission
directions can be searched in a potentially large angular space. Design options
are compared considering different scanning and signaling procedures to
evaluate access delay and system overhead. The channel structure and multiple
access issues are also considered. The analysis demonstrates significant
benefits of low-resolution fully digital architectures in comparison to single
stream analog beamforming.

这篇论文研究了毫米波通信在下一代移动通信系统中的应用，重点关注了初始接入过程中的设计挑战和各种选项，最终比较了不同扫描和信令过程对接入延迟和系统开销的影响，并考虑了频道结构和多路访问问题。分析结果表明，与单流模拟波束成形相比，低分辨率全数字架构具有显着优势。