etwork is the backbone that connects the access network with the packet core network and the internet. Here, the word internet is loosely High-level components used - it can be any AF or content server, such as Netflix, a server with custom content, or an IoT platform. The most important facets of the transport network are that it should be able to meet the latency and bandwidth requirements and also should be secure and not subject to attack by rogue elements. Now that we've understood the basic 5G network, let's move on to looking at the high-level components. High-level components Multiple components come together to bring up a 5G network. In this section, we will learn about the high-level components that are a must in creating and operating a 5G network. 5G provides a lot of flexibility in the design of the network - we will also discuss the options as we go over each high-level component. The access network The access network comprises mobile base stations (gNB), which may be split up further functionally and physically into the following components - a Centralized Unit (CU), a Distributed Unit (DU), and a Radio Unit (RU). When there is a functional and physical split of various components of a base station, it is called a distributed architecture, simply because a single function of a gNB is now distributed among other smaller components. This split is very useful to support lower-latency use cases and helps serve mobile edge computing use cases. Let us go over the components one by one: In the CU, the radio stack is decomposed to comprise Service Delivery Adaptation Protocol (SDAP) for NR, Packet Data Convergence Protocol (PDCP), which uses packet processing components, including ciphering and header compression, and Radio Resource Control (RRC), which is responsible for controlling radio channels. These components are not time-critical and hence they are good candidates for virtualization. The CU is generally deployed in remote near-edge data centers and is usually co-located with UPFs for low-latency ap