Relay has been a promising technique for extending the coverage area of a cellular network without incurring additional cost for wired backhaul. With this merit, relay technology has been widely considered for developing and deploying cellular networks such as IEEE 802.16j WiMAX and 3GPP LTE-Advanced. As a natural consequence, standardization for relay support is now being conducted in the 3GPP 5G NR work item called Integration of Access and Backhaul (IAB) in Rel-16, which enables cost-effective deployment of small cells through wireless backhauling. In Rel-16 IAB, however, only fixed relays are considered. In order to meet diverse 5G requirements under various deployment scenarios, mobile relays can be useful to provide enhanced user experience to the onboard passengers in, for example, trains and buses. Hence, in this column, focusing on realistic 5G high-mobility deployment scenarios, we provide a brief background and motivation for mobile relay and investigate potential technical challenges to be overcome in the future 5G releases.

中文翻译：

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5G移动中继技术

中继已成为一种有希望的技术，它可以扩展蜂窝网络的覆盖范围，而不会引起有线回程的额外费用。凭借此优点，中继技术已被广泛考虑用于开发和部署蜂窝网络，例如IEEE 802.16j WiMAX和3GPP LTE-Advanced。自然的结果是，目前在Rel-16中称为“接入与回程集成（IAB）”的3GPP 5G NR工作项中正在进行中继支持的标准化，这可以通过无线回程实现经济高效的小型小区部署。但是，在Rel-16 IAB中，仅考虑固定继电器。为了在各种部署方案下满足各种5G要求，移动中继可用于为火车和公共汽车等机上乘客提供增强的用户体验。因此，在本专栏中，