far are either part of 3GPP Release-15 specifications or targeting 3GPP Release-15 networks. Release-15, being the first 5G release by 3GPP, introduced the biggest changes into RAN architecture (compared with 4G); however, NG-RAN continues to evolve in Release-16 and beyond. In the present chapter we describe some (but definitely not all) NG-RAN evolution paths, which will help expanding 5G networks into new market segments and new deployment options. In particular, we define two important NG-RAN architecture enhancements: Relays, also referred to as Integrated Access-Backhaul (IAB), which will help deploying 5G in areas where operators do not have sufficient backhaul capacity. This is especially beneficial for dense small-cell deployments and mmWave. Satellite (access and backhaul), also referred to as non-terrestrial networks, will mark an important milestone with yet another industry embracing 3GPP technologies as opposed to the proprietary technologies used in the past. As mentioned above, relays and satellites are by no means the only NG-RAN evolution and expansion areas; however, these appear to be among the most important ones defined in Release-16. Wireless Relaying in 5G Georg Hampel Qualcomm Incorporated, US IAB introduces wireless relaying to 5G. While 3GPP has already specified relay solutions for 4G none of them enjoyed major commercial success. This is expected to change for 5G with the introduction of mm Wave access, which depends on relaying for economic network deployment. The wide bandwidth in the mmWave range provides abundant capacity, but the high propagation loss at these frequencies limits the practically achievable cell size requiring 5G Radio Access Network Architecture: The Dark Side of 5G, First Edition. Edited by Sasha Sirotkin. © 2021 John Wiley & Sons Ltd. Published 2021 by John Wiley & Sons Ltd. 5 NG-RAN Evolution densified network deployments to obtain sufficient area coverage. IAB aims to reduce the need for backhaul in such densified networks by allowing cells without fiber conne