ction to NSA networks An NSA network is one in which multiple radio technologies are combined to provide 5G coverage. A master node controls the control plane, and the user plane can be split between a master and a secondary node. As mentioned in the introduction, the main aim of introducing NSA networks was to gain speed in deployment, and this was primarily achieved by building on the existing 4G network and reusing its components, thus reducing the time to roll out drastically. Let us take an example of a 5G NSA network, and later, we will go over the various other types of NSA networks. The following figure illustrates 5G NSA option 3x: 5G Non-Standalone Networks EPC (5G-enabled) Option (3x) Figure 10.1 - 5G NSA option 3x This diagram shows what a typical deployment of NSA looks like. There is an existing Long-Term Evolution (LTE) evolved NodeB (eNB), which is connected to an existing 4G Evolved Packet Core (EPC) core network. Now, this is augmented by 5G gNodeB (gNB) New Radio (NR) coverage. Another way to look at this scenario is that in a service provider's existing LTE coverage area, a new 5G NR is introduced to increase capacity. This 5G radio is controlled by a master 4G eNB, which in turn is connected to the 4G core network EPC depicted by the dotted line. There is no 5G core network involved here. All the control plane signaling from EPC to gNB NR is handled by the master eNB. Hence the secondary gNB is completely managed by the master eNB, SO it cannot stand alone, thus the name NSA. Since there are two radios involved, the connectivity is also called dual connectivity (E-UTRA NR-Dual Connectivity (EN-DC)). Therefore NR is only a secondary node that is completely controlled by the master eNB. The data plane, however, can be tunneled via S1-U directly from the Serving Gateway (SGW) in the EPC gNB. When User Equipment (UE) is in the coverage area of this gNB, it is connected to a 5G radio, but at the backend, the 4G core network is still leveraged. Types of NSA networks The NSA options include options 