Why 5G Core is Important to Network Evolution

Ask any personal trainer how to improve physically and they will tell you to strengthen your core. That usually translates as more sit-ups, more crunches, more burpees and laying off the donuts and cookies. Likewise, the core is important to mobile operators needing to unlock the full potential of their 5G networks.   

 5G networks leverage a bevy of new technologies: fronthaul, cloud RAN, virtualization (NFV), software defined networking (SDN), multi-access edge computing (MEC), massive MIMO, etc. Operators around the world have deployed 5G in many different radiofrequencies, especially in the 3.5 GHz mid-band spectrum. Over time, 5G will replace 4G LTE networks and will be deployed across all the operators’ licensed bands. 

 For the wireless infrastructure industry, the deployment of 5G Stand Alone (SA) network architecture is important since it supports the use of more advanced 5G services, increases in 5G capacity and expansion of the networks. Remember, the initial 5G networks were deployed using the 4G LTE core – so-called 5G Non-standalone (NSA) with 5G New Radio (NR). New, revenue-generating 5G services that 5G SA supports include: 

• Network slicing 

• Ultra-low latency services 

• Low power connections 

• Roaming into enterprise private wireless networks. 

In short, 5G SA is the current goal of all of the MNOs and will support advanced services requiring more bandwidth, network capacity, lower latency and ultimately more infrastructure – towers, small cells, sectors, radios, backhaul and data centers. 5G SA is the end goal for 5G deployments. And although final decisions have not been made, it is possible the 5G core will support the initial 6G deployments at the end of the decade, just as the 4G core supported the initial 5G deployments. 

Before going further, we should discuss the differences between the LTE Evolved Packet Core (EVP) and the 5G Core. 3GPP TS 23.501 describes the system architecture for 5G (Release 15). According to the document published back in September 2018, the 5G system architecture leverages service-based interactions between control plane (CP) network functions according to the following principles which include but are not limited to: 

• The separation of user plane (UP) and control plane (CP) functions 

• A service-based architecture (SBA) that allows each Network Function (NF) to directly interact with other NFs as required 

• Minimize dependencies between the Access Network (AN) and the Core Network (CN) 

• Support “stateless” network functions where the compute resource is decoupled from the storage resource. 

In essence, this means that the 5G Core functions are deployed in software running on a commercial hardware platform. Unlike in the EPC, where specific functions were deployed in specific hardware, the 5G Core is designed to be deployed in the cloud.  Thus, specific EPC servers and functions are redefined in the 5G Core in software functions. 

The 5G SA Core was introduced in Release 16 of the technical specifications – this used the 5G new radios but had the new 5G Core, replacing the 4G EPC.  With the 5G Core, new functions and applications are enabled and hence new monetization opportunities. The ultimate goal of the mobile operators is to use just 5G and to decommission their 4G networks.  This means a 5G standalone network (5G SA) that is 5G from end to end. 

As MNOs move to the 5G SA Core, they will phase out their 4G core such that the new 5G Core starts to control both legacy LTE and the new 5G NR RAN. After that is accomplished, operators will gradually phase out their LTE RAN by refarming spectrum to 5G NR. And then, at some indeterminate time in the future, they will be full-fledged 5G Standalone operators. This is simple to say but are not simple to accomplish, given that the mobile operator has to maintain service for millions, tens of millions or even hundreds of millions of subscribers. To use another analogy, migrating from 4G to 5G SA is the equivalent of changing the gearbox on a car while driving down the road at 70 mph.  And learning to speak French at the same time. 

Subsequent releases of the 3GPP technical specifications are introducing new features in 5G, using the 5G Core as a basis.  Release 17 adds more features and Release 18 moves to 5G Advanced, introducing functions and applications specifically for artificial intelligence (AI) and machine learning (ML) in the network and support for augmented reality and virtual reality. Release 18 is expected to be introduced sometime in 2026. Later, Releases 19 and 20 will further improve on 5G Advanced with more AI and ML features plus support for more advanced MIMO and energy conservation. Release 21 is targeted as the first 6G release to be finalized toward the end of the decade and launched shortly thereafter. 

New functions and features, 5G Advanced and 6G will not be possible with the 5G SA Core being deployed. For this reason, the importance of the core should not be overlooked – while much of the work and investment goes into deploying radios on towers (obviously because a large number of 5G radios are required working in multiple frequency bands), the 5G Core is critical. 

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