 the context of dual connectivity, the RAN node is the master RAN node. The master RAN node effectively controls any dual connectivity activity that takes place, which includes adding a secondary RAN node. This is where the dual connectivity terminology comes from. With this approach, a secondary RAN node works in parallel with the master RAN node to improve the effective data rate that the UE can achieve. To accomplish this, there must be a control and user plane connection between the secondary and master nodes. Certainly, the data rate for the subscriber device can be significantly increased by taking this approach. The terminology used between the master RAN node and the secondary RAN node varies depending on the network architecture and mobile technology. In 5G, for instance, the master and secondary RAN nodes could both be gNBs. Alternatively, the master could be an ng-eNB and the secondary could be a gNB. So, there are several different options available. From the service provider's perspective, it is up to them how to deploy their dual connectivity solution. Master RAN Network Device uses data capacity from two User and RAN nodes Control Plane Secondary RAN Node Figure 1.8 - Dual connectivity Certainly, there are different approaches where a mixture of technologies is used between the master and secondary RAN nodes, as can be found in 5G NSA deployments. Fundamentally, by using these Introduction to 5G two nodes together, better coverage and improved data rates can be provided for the subscribers. Note that the UE has also got to support dual connectivity. This is particularly important if, for example, the master RAN node is an eNB and the secondary RAN node is a gNB, in which the device is then supporting 4G and 5G radios simultaneously. Small cells Small cells are nothing new; they are not a new technology. Small cells have already been in use with previous technologies for several years. In this section, small cells will be examined in the context of dual connectivity in 5G. 5G is set to really benefi