loyment that was ushered in by 5G architecture. The following table provides a list of all the various options: Network Type Connectivity Core Network Master RAT Secondary RAT 3GPP Term Option Standalone Option 1 Standalone Option 2 Non-Standalone Option 3 EN-DC Non-Standalone Option 4 NE-DC Standalone Option 5 Non-Standalone Option 7 NGEN-DC We can see that 5G can be rolled out in various combinations of cores and radios; some of them are SA options (which we will explore in the next chapter), and some of them are NSA options: Option 1 is an SA option that denotes a 4G network, comprising 4G RAN and 4G packet core with no secondary radio. 5G Non-Standalone Networks Option 2 is an SA option comprising a 5G core and 5G radio. This is also a popular deployment option across service providers. This also does not have a secondary radio, hence SA. Option 3 is an NSA option. This comprises a 4G packet core connected to a 4G radio as the master node and a secondary 5G radio. This is a popular NSA deployment choice among operators. Option 4 is an NSA option with a 5G packet core connected to a 5G radio as master and a secondary enhanced LTE eNB, which is an eNB that can connect to a 5G core; it is primarily used to serve a 5G device over 4G radio. Option 5 is an SA option with a 5G core connected to an enhanced LTE radio. Option 7 is an NSA option with a 5G core connected to a master enhanced LTE radio and a secondary NR node. Option 4, option 5, and option 7 benefit the service providers and their subscribers to continue using legacy 4G equipment while connecting to 5GC. Next, we will review one of the most popular NSA network architectures. The architecture of the option 3 NSA network The following diagram shows the high-level components of an option 3-based NSA network: MME/S-GW MME/S-GW EN-gNB EN-gNB E-UTRAN (191) Figure 10.6 - 5G option 3 NSA network A deep dive into NSA networks When considering the requirements to implement an option 3-based NSA design, the following are some key aspects to take into account: 5G o