Prior to its release, 5G had been long touted as a major upgrade to cellular networking technology. With 5G no longer in its infancy, U.S. mobile network operators, or MNOs, have started to distribute 5G across the nation.

MNOs have two main options to choose from when deploying 5G: non-standalone (NSA) and standalone (SA).

NSA dominated as the top choice for initial 5G deployments among MNOs, thanks to existing cellular infrastructure. But, as SA 5G deployments take off, it's important to understand the distinctions between the two. Both approaches are valid ways of constructing a 5G network, but the chosen deployment mode determines how efficiently the 5G network operates.

Both NSA and SA use the 5G New Radio (5G NR) interface, enabling them to deliver features and capabilities based on the standards defined by the 3rd Generation Partnership Project (3GPP). 5G NR offers myriad use cases, but one of its most essential features is it provides a path from 4G LTE to 5G.

When it comes to NSA 5G, the clue is in the name: It's 5G that can't stand on its own in terms of infrastructure. NSA is a 5G radio access network (RAN) that operates on a legacy 4G LTE core -- known as Evolved Packet Core (EPC) -- and manages control plane functions. NSA includes both a 4G and 5G base station, but the 4G base station takes precedence. Because the NR control plane anchors to the EPC, radio frequency signals forward to the primary 4G base station.

NSA 5G, also known as Release 15 by 3GPP, is considered the first stage of 5G. Initial 5G deployments used NSA because MNOs could use their current infrastructure to build a 5G network. Carriers with 4G LTE networks could implement a 5G RAN on top of their existing architectures. NSA 5G can serve as a steppingstone for carriers unprepared to make a hefty investment when transitioning from legacy 4G LTE to 5G networks.

The drawback of NSA 5G, however, is it can't deliver certain capabilities that a pure, unfettered SA 5G network can. For example, NSA doesn't enable the low latency that is one of the biggest draws to 5G. Another disadvantage of NSA is it requires a higher level of energy to power 5G networks with 4G infrastructure. 5G NR is more energy-efficient than LTE, IEEE reported, but using two different forms of cellular technology massively increases power consumption in a network.

NSA 5G also shouldn't be confused with dynamic spectrum sharing (DSS), another method of deploying 5G with 4G technology. While NSA creates a 5G network with 4G infrastructure using dual connectivity, DSS permits 4G LTE and 5G NR to coexist in the same frequency band. 5G networks have a variety of spectrum bands available for use, and DSS distributes spectrum between bands based on user demands.

SA 5G networks include both a 5G RAN and a cloud-native 5G core, something NSA networks lack and substitute with a 4G core. SA networks can perform essential 5G functions, such as reducing latency, improving network performance and centrally controlling network management functions, because of their 5G cores.

SA requires MNOs to configure a completely new architecture and learn how to manage it. As carriers waited for SA technology to mature, most opted to simply reconfigure their 4G networks to support 5G, as it was cheaper and more convenient.

New providers without established 4G core networks couldn't follow that strategy, though. Because they couldn't rely on a 4G core, they needed to build their 5G infrastructure from scratch. SA is now looking to take the crown among MNOs, as carriers start to deploy it to take advantage of the improvements it offers over NSA.

The biggest disadvantage of SA is it's costly to implement and time-consuming for network professionals to learn the new 5G core infrastructure. Regardless, MNOs are making the shift to SA because NSA can serve as a step toward 5G networking, but it isn't considered true 5G due to its reliance on 4G LTE.

Ultimately, the biggest difference between NSA and SA is how each mode provides 5G. NSA uses a 5G RAN, as well as a 4G LTE core, while SA is an end-to-end 5G network with both a 5G RAN and NR core. Their methods of deployment determine how each mode supports the 3GPP-defined NR specifications.

5G NR specifications include the following:

All three features support an array of industries and services, including emerging sectors, such as IoT. However, SA 5G is the only deployment mode that supports all three specifications. NSA 5G can only enable enhanced mobile broadband because it has a 4G core that can extend to support the specification. SA can enable all three features because it has a more powerful and more flexible 5G core.

According to an October 2021 Exfo and Heavy Reading study, 88% of MNOs based in North America and Europe have planned to deploy SA 5G within the next year. Around 49% plan to deploy it in 2022, while another 39% are planning to deploy it by 2023. Despite the simplicity and inexpensive costs of deploying NSA, carriers are making the move to SA 5G to reap the most beneficial and anticipated capabilities of the technology.

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