needs to be retained Wide area NR can be supported IMS voice can be supported No CS interworking from 5GS NSA option 3 to SA Full set of 5G use cases can Packet core migration option 2 be supported needs to be accounted for EPC needs to be retained Wide area NR can be supported IMS voice can be supported No CS interworking from 5GS NSA option 3 to NSA Full set of 5G use cases supported Core migration needs to option 4/SA option 2 be accounted for Initially limited use cases until 5GC is fully operational Impact on NR and LTE during migration IMS voice supported No CS interworking with 5GS The following diagram shows 5G deployment options mapping into spectrum bands: 5G Non-Standalone Networks Baseline: option 1 Baseline: option 1 Add option 2 Option 2 on Extend wide wide area LTE-LTE CA New NR spectrum 5GC NR SA for NR in new or NR on additional on mid or high local use cases in existing low bands bands bands LTE-NR mid/high bands with spectrum DC (EN-DC) sharing/ refarming NR-NR CA High bands (24GHz - 40GHz) Mid bands (3.5GHz - 8GHz) Mid bands (1GHz - 2.6GHz) Low bands (sub - 1GHz) LTE + NR_ Figure 10.7 - Migration path from 4G to 5G across spectrum bands The current 4G deployments leverage low bands of the spectrum, which are sub-1 GHz and 1-3 GHz, as shown in the preceding figure. Then comes 5G NR, which is deployed in the mid bands of 3.5-8 GHz; this greatly augments the capacity of the network and can support higher data rates and low-latency use cases. NR in mm Wave, along with existing wide area LTE RAN, ensures both good coverage and high throughput and serves subscribers with both 4G and 5G UEs. High-band NR (mmWave) with a 24-40 GHz downlink can be leveraged to further add capacity. With the deployment of a 5G core, option 2 comes into play. This is initially the case, in the mm Wave spectrum and mid bands for fixed access, but later, when the LTE spectrum can be re-farmed, it can be extended to cover wider areas. In this case, tight interworking with LTE can ensure seamless handover between 4G and 5G d