Arsitektur 5G: Pilihan Implementasi

With an already deployed 4G RAN/EPC in the field and a new 5G RAN/NG-Core deployment underway, we can’t ignore the issue of transitioning from 4G to 5G (an issue the IP-world has been grappling with for 20 years). 3GPP officially spells out multiple deployment options, which can be summarized as follows.

• Standalone 4G / Stand-Alone 5G
• Non-Standalone (4G+5G RAN) over 4G’s EPC
• Non-Standalone (4G+5G RAN) over 5G’s NG-Core

The second of the three options, which is generally referred to as “NSA“, involves 5G base stations being deployed alongside the existing 4G base stations in a given geography to provide a data-rate and capacity boost. In NSA, control plane traffic between the user equipment and the 4G Mobile Core utilizes (i.e., is forwarded through) 4G base stations, and the 5G base stations are used only to carry user traffic. Eventually, it is expected that operators complete their migration to 5G by deploying NG Core and connecting their 5G base stations to it for Standalone (SA) operation. NSA and SA operations are illustrated in Figure 18.

_images/Slide38.png Figure 18. NSA and SA options for 5G deployment.

One reason we call attention to the phasing issue is that we face a similar challenge in the chapters that follow. The closer the following discussion gets to implementation details, the more specific we have to be about whether we are using 4G components or 5G components. As a general rule, we use 4G components—particularly with respect to the Mobile Core, since that’s what’s available in open source today—and trust the reader can make the appropriate substitution without loss of generality. Like the broader industry, the open source community is in the process of incrementally evolving its 4G code base into its 5G-compliant counterpart.