elecommunication management; Principles and high level requirements. Available at: www.3gpp.org (accessed May 29, 2020). 3GPP Technical Specification 38.300 (2019). Technical Specification Group Radio Access Network; NR; NR and NG-RAN Overall Description; Stage 2. Available at: www.3gpp.org (accessed May 29, 2020). 3GPP Technical Specification 23.222 (2019). Common API Framework for 3GPP Northbound APIs. Available at: www.3gpp.org (accessed May 29, 2020). 3GPP RP-193255 (2019). New WID on enhancement of data collection for SON/MDT in NR, RP-193255. 6 Enabling Technologies Transport Network Yaakov (J.) Stein, Yuri Gittik, and Ron Insler RAD Data Communications, Ltd., Israel In this section we discuss various transport network technologies used for backhaul (i.e. connecting NG-RAN to 5GC), fronthaul (i.e. connecting NG-RAN to RRG), and midhaul (connecting network nodes in split NG-RAN architecture). This is illustrated in Figure 6.6.1, where the usage of various NG-RAN functional split architectures (see Chapter 4) is also shown. Figure 6.6.1 shows backhaul, midhaul, and fronthaul as straight lines connecting network nodes, but this is a bit misleading as in practice any haul (referred to as xHaul in this book) can have a complex network topology and many links, using many different technologies. This aspect is often overlooked in technical specifications (e.g. in 3GPP) and other network architecture documents. In the present section we discuss this topic (the transport network) in more detail. 6.6.1 Key Ideas The transition from 4G to 5G will strongly impact the transport network, due to require- ments for higher data rates, lower latency, enhanced reliability, energy efficiency, and heightened dynamicity. Choice of 5G RAN segment defined by functional split (fronthaul through midhaul to backhaul) and RAN planning factors (density, distances, placement of Points of Presence [PoPs], etc.) deeply influence new requirements for transport. In addition, delivery of disparate services (eMBB, URLLC, and mMTC) requires di