What are standalone (SA) and non-standalone (NSA) 5G NR mobile networks?

For many people, 5G is probably just another generation of mobile networks with some additional features. Let’s face it; we see a new generation of mobile networks nearly every ten years, and now that we already get reliable mobile broadband speeds with 4G, do we really need yet another upgrade? It is not really a quiz question, but the answer may depend on what you want to use 5G for? One thing is for sure that as the years pass by, you are likely to benefit from 5G either directly or indirectly. The earlier mobile network technologies mainly focused on voice and text, and later with 3G and 4G, we got into a world where mobile broadband could be seen as a potential alternative to fixed broadband. While 5G can also do all that, potentially in a much better way than 4G, that’s not really what 5G is all about. Mobile broadband is definitely one key aspect of 5G networks, but the real value of 5G networks lies in the capabilities they offer to digitise a wide range of industries. The 5G New Radio (NR) technology can provide ultra-low latencies while also supporting a vast number of low-powered devices. That key difference allows 5G to enable futuristic use cases that were not possible with earlier technologies. This is where the 5G standalone (SA) and non-standalone (NSA) deployment models play a vital role.

What is non-standalone 5G NR (NSA)?

The non-standalone deployment model of 5G NR is where the 5G services cannot be enabled through an end-to-end 5G network. The non-standalone 5G network (NSA) requires an existing 4G LTE network to function. Technically this means relying on some parts of the 4G LTE network infrastructure to connect customers to 5G network. This option can be seen in multiple ways. On the hand one, it is a more cost-effective option as it allows mobile operators with existing 4G LTE networks to get a quick start with 5G without having to invest in a full 5G network. But on the other hand, there are some compromises the operators have to make because not having a full 5G network has its limitations. If the key service a mobile operator wants to offer is the high-speed internet, this option can give them a swift start and a great marketing opportunity.

How does non-standalone 5G NR (NSA) work?

The non-standalone version of 5G New Radio (NR), NSA, uses the 4G LTE network for some parts of the overall 5G service. In the NSA model, the end-user side of the service where higher data is required utilises the 5G radio network capabilities. However, the control functions such as signalling still use the existing 4G LTE core network. This requires installing 5G NR base stations on the radio network side and utilising EPC- Evolved Packet Core with 5G specific updates for both 4G and 5G core network functions. It means that the radio network works in such a way that the user-level functions, e.g. mobile data, QoS etc. utilise the 5G radio network node gNodeB (gNB), and the 4G radio base station, eNodeB (eNB) manages the control functions for 5G through a concept called dual-connectivity.

High-level diagram of a deployment model for non-standalone 5G - NSA
High-level diagram of a deployment model for non-standalone 5G – NSA

NSA can be seen as an early version of the full 5G NR network, using lower frequency bands to provide data-speed focused 5G network coverage. It mainly allows mobile operators to offer Enhanced Mobile Broadband services to their customers. The average 5G data speeds are considerably higher than the average 4G speeds and good enough for streaming 4k and even 8k videos. The improved latency in 5G NR networks also makes augmented reality (AR) and virtual reality (VR) use cases possible. The other more futuristic use cases of 5G need ultra-high reliability and ultra-low latencies which are not possible through 5G NSA.

What is 5G NR standalone (SA)?

The standalone model for 5G New Radio (NR) networks is an independent deployment model that offers mobile services through an end-to-end 5G network. The standalone model, SA, can deliver the futuristic use cases of 5G that require more than just high-speed data. With SA, a mobile network can achieve ultra-low latencies and ultra-high reliability which are needed for many business-to-business use cases like self-driving cars, manufacturing factories etc. Many use cases for SA will emerge over time as the 5G network coverage becomes more widely available.

Standalone and non-standalone variants of 5G NR are not so much about which one is better, but more about what a mobile operator wants to achieve with 5G. The choice an operator makes will have to align with market their strategy as to who the customers are and what they want to offer them. We have an earlier post that outlines what consumers and business customer segments meant to mobile operators. Depending on the use cases an operator wants to target, NSA maybe more on the consumer side, whereas SA may be better placed to serve enterprise-level use cases.

How does 5G NR standalone (SA) work?

In standalone 5G NR, SA, the mobile network functions including the control plane as well as the user plane are both 5G specific. From an architectural perspective, the 5G NR base stations form part of radio network that works alongside a cloud-native 5G Core network.

With cloud-native 5G core network, the connectivity for any 5G devices uses the gNB node for both user and control planes. If any 4G devices require access to the LTE network through the 5G Core, they connect to ‘next-generation’ eNodeB instead of the regular eNodeB to be able to communicate via the 5G Core network. The next-generation eNodeB is abbreviated as ng-eNB which is often confused with gNB.

High-level diagram of a Standalone 5G NR deployment - SA, without an existing 4G LTE network
High-level diagram of a Standalone 5G NR deployment – SA, without an existing 4G LTE network

Standalone 5G NR makes use of the mid and high range frequency bands to enable advanced use cases that require ultra-low latency. It allows mobile operators to do a lot more than just offering high-speed internet services. With standalone 5GNR, mobile operators can support use cases like Ultra-Reliable Low Latency Communications (URLLC) and Massive Machine Type Communications (mMTC). These use cases can help digitise market verticals such as the manufacturing industry. Network slicing is another key feature that works with the standalone variant of 5G. It allows mobile operators to create virtual sub-networks for specific (business) customers. Have a look at this post to learn about the frequency bands that the 5G technology uses.

What is the difference between standalone and non-standalone 5G then?

Non-standalone (NSA) and standalone (SA) are two different modes for the deployment of 5G New Radio (NR) mobile networks. The non-standalone variant of 5G NR is a deployment model that uses the existing 4G LTE network infrastructure to enable 5G. Standalone is when 5G NR networks are deployed without any dependency on the existing 4G LTE networks.

The standalone and non-standalone deployment models of 5G NR do not have to be mutually exclusive. Just because a mobile operator decides to go with NSA does not mean that they have made their choice and must always use that model for their network evolution. In fact, NSA can work for an operator as an interim step towards SA. When 5G networks reach a higher level of maturity over the next few years, we may see more 5G-only or standalone 5G network deployments.

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