With the introduction of new technologies such as unmanned aerial vehicles (UAVs), high altitude platforms (HAPS), millimeter wave (mmWave) frequencies, massive multiple-input multiple-output (MIMO), and beamforming, wireless backhaul is expected to be an integral part of the 5G networks. While this concept is nothing new, it was shortcoming in terms of performance compared to the fiber backhauling. However, with these new technologies, fiber is no longer the foremost technology for backhauling. With the projected densification of networks, wireless backhaul has become mandatory to use. There are still challenges to be tackled if wireless backhaul is to be used efficiently. Resource allocation, deployment, scheduling, power management and energy efficiency are some of these problems. Wireless backhaul also acts as an enabler for new technologies and improves some of the existing ones significantly. To name a few, rural connectivity, satellite communication, and mobile edge computing are some concepts for which wireless backhauling acts as an enabler. Small cell usage with wireless backhaul presents different security challenges. Governing bodies of cellular networks have standardization efforts going on especially for the integrated access and backhaul (IAB) concept, and this is briefly mentioned. Finally, wireless backhaul is also projected to be an important part of the beyond 5G networks, and newly developed concepts such as cell-free networking, ultra-massive MIMO, and extremely dense network show this trend as well. In this survey, we present the aforementioned issues, challenges, opportunities, and applications of wireless backhaul in 5G, while briefly mentioning concepts related to wireless backhaul beyond 5G alongside with security and standardization issues.

翻译：随着无人驾驶飞行器(UAVs)、高空平台(HAPS)、毫米波(mmWave)频率、大规模多投多发多发(IMIMO)和波形成形等新技术的引入,无线回路预计将成为5G网络的一个组成部分。虽然这个概念并不新鲜,但与纤维回路相比,在性能方面还存在缺陷。然而,有了这些新技术,纤维不再是反向航行的最主要技术。随着网络预测的密度化,无线回路(mmWave)频率、无线回路(mmWave)频率(mmWave)频率(mm Wife)频率(mm Wife)频率、大规模多投放多投放多发多发多发多发多发(MIMO)频率(m)和光线性回路(M)应用的小型回路路(M)的使用也带来了不同的挑战。资源分配、部署、时间安排、电力管理和节能效率(G)的回路路路系(Lial)网络(LOL)的动态(Liel-G)概念也与Leal-G(Lial-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-L-