Millimeter-wave (mmWave) communication is regarded as the key enabling component for fifth-generation (5G) cellular systems due to the large available spectrum bandwidth. To make mmWave new radio (NR) a reality, tremendous efforts have been exerted from the industry and academia. Performance evaluation of mmWave NR is a mandatory step and the key to ensuring the success of mmWave 5G deployment. Over-the-air (OTA) radiated method of testing mmWave NR in laboratory conditions is highly attractive, since it facilitates virtual field testing of mmWave devices in realistic propagation conditions. In this paper, we first discuss the need for and challenges in OTA measurement of mmWave 5G NR under fading channel conditions. After that, two promising candidate solutions, i.e., wireless cable and multi-probe anechoic chamber (MPAC), are detailed. Their principles, applicability for mmWave NR, and main challenges are discussed. Furthermore, preliminary experimental validation results in a frequency range 2 anechoic chamber are demonstrated for the wireless cable and MPAC methods at 28 GHz.

由于可用频谱带宽较大，毫米波（mmWave）通信被视为第五代（5G）蜂窝系统的关键启用组件。为了使mmWave新无线电（NR）成为现实，业界和学术界已经做出了巨大的努力。mmWave NR的性能评估是必不可少的步骤，是确保mmWave 5G部署成功的关键。在实验室条件下测试mmWave NR的空中（OTA）辐射方法极具吸引力，因为它有助于在实际的传播条件下对mmWave器件进行虚拟现场测试。在本文中，我们首先讨论在衰落信道条件下mmWave 5G NR OTA测量的需求和挑战。之后，详细介绍了两种有希望的候选解决方案，即无线电缆和多探头电波暗室（MPAC）。讨论了它们的原理，对mmWave NR的适用性以及主要挑战。此外，在28 GHz的无线电缆和MPAC方法中，已证明了在频率范围为2的消声室中的初步实验验证结果。