What is 5G Standalone (SA) / When will it start in Japan ?


5G services will be launched in the U.S. and South Korea in 2018 and 5G has been available in Japan starting in March 2020, but these 5G are not real 5G.

This article provides an easy-to-understand explanation of what the Standalone (SA), which is said to be the real 5G, is and why the SA is required.


NSA, SA, what is the difference ?

Majority of carriers using NSA as of Sept, 2020

There are 2 types of 5G networks infrastructures, one is the Non-Standalone (NSA) and the other is Standalone (SA). As of September 2020, the majority of carriers that are launching 5G services use the NSA, and only a small number of carriers use the SA, such as T-Mobile in the United States or Elisa in Finland. Docomo, KDDI and SoftBank in Japan also offer 5G in the NSA system.


What’s the difference between NSA and SA?

What is the difference between the NSA and the SA ? The following is a comparison of the network architecture of the NSA and SA methods:

The NSA is an architecture that leverages a 4G LTE network to provide 5G services. As shown in the figure above, the 5G base station is connected to a 4G base station and a 4G core network, and 5G data is provided over a 4G network A major advantage of the NSA is that it allows you to deploy 5G faster by using existing 4G equipment. Therefore, many carriers are launching 5G services in the NSA system to speed up the expansion of the 5G area.

On the other hand, The SA is a network architecture dedicated to 5G. The 5G system is completely independent and does not depend on the 4G system. The SA require 5GC, which is a dedicated 5G core network that is different from the 4G EPC.

Is EPC different from 5GC ?

The following illustration shows how the It shows EPC and 5GC.

Comparing EPC and 5GC, there appears to be a significant difference in the number of systems in 5GC, but there is no significant difference between EPC and 5GC for basic functionality. For example, EPC consists of MME, SGW, PGW, PCRF, and HSS, but features similar to MME are implemented in 5GC AMF and SMF, and SGW and PGW implement similar features in 5GC SMF and UPF.

One of the differences between EPC and 5GC is that EPC connects systems that need to work together, such as MME and HSS, and MME and SGW, whereas 5GC uses Service Based Architecture (SBA) that allows all systems to communicate with each other. The benefit of this is that it gives you the flexibility to respond when new systems are added or new sequences are added when new services are offered in the future.

The difference between EPC and 5GC is that 5GC is a cloud-native premise. Some carriers have already deployed virtualization in their EPCs, but this virtualization has only migrated the functionality of their existing 4G EPCs to a virtualized environment. In other words, because the system was originally developed with dedicated software that operates on the dedicated hardware of the communication infrastructure vendor rather than the cloud premise, and because it is not designed on the premise of virtualization, there are many cases where the benefits of virtualization cannot be fully utilized.

On the other hand, 5GC is designed to be optimized for the cloud because each infrastructure vendor is developing a new system based on the assumption that it will be used in the cloud. Many carriers plan to use 5GC in a container environment, which will shorten the lifecycle of 5G service delivery or lower operating costs.


Full-scale 5G service requires SA

Why do I need the SA even though 5G services can also be provided by NSA?

The SA is necessary because it is not possible to provide services that take advantage of the characteristics of 5G without the introduction of the SA.

5G has three major features, enhanced Mobile Broadband (eMBB), Ultra-Low Latency (URLLC), and massive Machine Type Communication (mMTC), but the NSA can only provide “eMBB.” The NSA doesn’t matter if 5G is provided as a mere high-speed communication system as an extension of the previous 4G, but the SA is required to achieve “URLLC” and “mMTC”. The NSA is a major factor in the use of 4G systems, which can shackle 4G systems in order to achieve “URLLC” and “mMTC.”

5G is expected not only in the telecommunications market but also in various markets, but the main reason is that it allows for ultra-low latency communication and simultaneous connection of many terminals, which has been difficult to achieve.

For example, in the game industry, It is expected to be used in AR games, and in order to realize it, it is necessary to have an ultra-low latency communication environment that exchanges information in real time, or it is expected to be used in a smart factory where everything is connected to the network in the factory, and an environment where a large number of devices can be connected in a specific area is required.


Japan will start SA in 2021

The SA is essential for providing the three major features of 5G “enhanced Mobile Broadband (eMBB)”, “Ultra Law Latency and Reliability (URLLC)” and “massive Machine Type Communication (mMTC)”, and T-mobile in the United States was the first in the world to be available in August 2020. In addition, Finnish carrier Elisa has also introduced SA, which are expected to be introduced in South Korea and China by the end of fiscal 2020.

In Japan, Docomo and KDDI are planning to introduce the SA in 2021, and it is likely to take some time to implement the SA, but due to high expectations from various industries, various 5G services and use cases may spread at once after SA starts.