School of Electrical and Electronics Engineering, College of Engineering, Chung-Ang University, 221, Heukseok-Dong, Dongjak-Gu, Seoul 156-756, Korea.
Sensors (Basel). 2018 Sep 21;18(10):3194. doi: 10.3390/s18103194.
Owing to the rapid growth in wireless data traffic, millimeter-wave (mm-wave) communications have shown tremendous promise and are considered an attractive technique in fifth-generation (5G) wireless communication systems. However, to design robust communication systems, it is important to understand the channel dynamics with respect to space and time at these frequencies. Millimeter-wave signals are highly susceptible to blocking, and they have communication limitations owing to their poor signal attenuation compared with microwave signals. Therefore, by employing highly directional antennas, co-channel interference to or from other systems can be alleviated using line-of-sight (LOS) propagation. Because of the ability to shape, switch, or scan the propagating beam, phased arrays play an important role in advanced wireless communication systems. Beam-switching, beam-scanning, and multibeam arrays can be realized at mm-wave frequencies using analog or digital system architectures. This review article presents state-of-the-art phased arrays for mm-wave mobile terminals (MSs) and base stations (BSs), with an emphasis on beamforming arrays. We also discuss challenges and strategies used to address unfavorable path loss and blockage issues related to mm-wave applications, which sets future directions.
由于无线数据流量的快速增长，毫米波（mmWave）通信技术显示出了巨大的潜力，被认为是第五代（5G）无线通信系统中的一项有吸引力的技术。然而，为了设计稳健的通信系统，了解这些频率下的空间和时间信道动态特性非常重要。毫米波信号极易被阻断，与微波信号相比，其信号衰减较差，因此通信受到限制。因此，通过采用高指向性天线，可以利用视距（LOS）传播来减轻来自或传向其他系统的同信道干扰。相控阵在先进的无线通信系统中起着重要作用，因为它能够对传播波束进行塑形、切换或扫描。在毫米波频率下，可以使用模拟或数字系统架构来实现波束切换、波束扫描和多波束阵列。本文主要介绍用于毫米波移动终端（MS）和基站（BS）的相控阵的最新技术，重点介绍波束形成阵列。我们还讨论了为解决与毫米波应用相关的不利路径损耗和阻挡问题而采用的挑战和策略，这些问题为未来指明了方向。
