if the following conditions are met: New satellite link model Terrestrial model based on TR38.901 Terrestrial Dynamic Dynamic Path loss & Convolution delay attenuation shadowing Satellite Satellite Scintillation, Scenario- LSPs, SSPs orbit Doppler Rain & cloud Specific shift macro-cell parameters Figure 5.3.10 Combined satellite and terrestrial channel model methodology. (Source: Reproduced by permission of © 3GPP). 5 NG-RAN Evolution S-band with channel bandwidth up to 5 MHz; Minimum of 20° elevation; Rural, suburban, or urban environment; Quasi-line-of-sight conditions (fading margin of approx. 5 dB). 5.3.7 Outlook 3GPP has conducted several studies in Release-15 and Release-16 on enhancements required for NG-RAN architecture, as well as the NR physical layer and protocol stack to be deployed with NTN. At least some players in the satellite community envision deploying NR-based NTN by 2025, encompassing all deployment options, that is, GEO, MEO, LEO, and HAPS. The vision is to deploy NTNs as part of 5G by 2025 in order to meet the challenges of mobile network operators and verticals in terms of reachability, reliability, and resiliency. This encompasses all deployment options like GEO, MEO, LEO, as well as HAPS. It has been identified that NTN solutions introduce potentially new constraints compared with typical cellular deployments due to moving cell patterns, larger Doppler shifts and vari- ation, larger and varying propagation delays, larger cell sizes, the highly frequency selective propagation channel, the power limited link budget, and feeder link handover. Depending on the considered NTN scenario (orbit, device, frequency band), the following NG-RAN features may need to be enhanced: random access, uplink/downlink synchroniza- tion, HARQ, user-plane timers, idle/connected mode mobility, feeder link handover pro- cedure, radio resource management, and multi-connectivity/mobility management across cellular/NTN access. At the time of writing this book, 3GPP has approved a work item (3GPP RP-193234) for norma