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Deploying 5G in NSA/SA Mode

[California Institute of Technology - Los Angeles Times]

- Overview

Breakthrough technologies that are integral to 5G, such as Massive MIMO, network slicing, beamforming and network function virtualization (NFV) require phased approaches to new 5G network deployment. They also require significant investment, with telecom operators expected to spend upwards of $300 billion on new 5G core network deployment over the next decade.

Unlike past historical transitions in wireless architecture, 5G represents an ongoing evolution of existing networks rather than the wholesale replacement or “forklift” approach to deployment. For LTE deployment, the wholesale approach limited financial payback for many operators. Incremental 5G network deployment, with 5G elements layered on top of legacy architecture, is commonly viewed as a prudent way to reduce CapEx spending and minimize financial risk. 

The service-based 5G architecture, along with core network slicing technology, facilitate a diversity of new offerings that can enhance existing use cases while enabling new ones. 5G network deployment options are dependent on the business needs and preferences of the operator. 

Enhanced mobile broadband (eMBB) is expected to be the biggest global 5G use case in the short term. Operators intending to leverage the exponential increase in massive machine type communications (mMTC) or ultra-low latency communication (URLLC) are adapting their 5G deployment strategies accordingly. The deployment model depends on the densification and coverage required for targeted use cases and the allocated spectrum for each network. 


- 5G Non-standalone (NSA) and Standalone (SA) Modes

When planning and testing 5G, it is important to understand that 5G comes with two modes: non-standalone (NSA) and standalone (SA). Mobile Operators can opt for either (or both) when transitioning from 4G to 5G. 

Most 5G rollouts so far have been NSA deployments; these have focused on providing enhanced mobile broadband (higher data-bandwidth) and reliable connectivity. This means that all these 5G networks have been added to an existing 4G infrastructure. So far, the majority of 5G customers have rolled out 5G NR NSA and the majority have decided to use Dynamic Spectrum Sharing (DSS) to speed up implementation.

The first rollout of 5G networks are NSA deployments that focus on enhanced mobile broadband to provide higher data-bandwidth and reliable connectivity. They are in line with the 3GPP specification that early rollouts of 5G networks and devices be brought under NSA operation – meaning, 5G networks will be aided by existing 4G infrastructure. So service providers who want to be first to offer 5G speeds will start with NSA and, once 5G coverage is established, implement standalone 5G.


- 5G NR Non-standalone (NSA) Considerations

For mobile operators looking to deliver better data throughput quickly, or to handle urgent LTE congestion, NSA mode makes the most sense because it allows them to leverage their existing network assets rather than deploying a completely new end-to-end 5G network. 

NSA allows an operator to launch 5G quickly for eMBB to gain thought and market leadership.  Operators can leverage their existing LTE/VoLTE footprint to utilize their LTE installed base and increase capacity. Network Slicing, URLLC and mMTC won’t be supported, but improved broadband speeds will enable services such as ultra HD 4K-8K video streaming, augmented reality (AR)/virtual reality (VR) and an immersive media experience.


- 5G NR Standalone (SA) Considerations

5G use cases requiring ultra-low latency and much higher capacity will only be feasible with the SA 5G NR and the 3GPP core network architecture for 5G Core (5GC). This means that there are service providers who prefer to go straight from 4G to standalone 5G, which offers greater possibilities to tap new 5G use cases, especially for enterprises. Together with industry peers who have already deployed NSA 5G, they can start to benefit from the advantages of standalone 5G, which is the eventual architecture of all 5G radio networks.

For those who want to offer new services to Industry 4.0, Standalone 5G NR is better aligned to support the new cases and unlock the power of the next-generation mobile technology. The SA version, which does not rely on LTE, allows an operator to address massive machine-to-machine communications, or ultrareliable low latency IoT. It also provides network slicing functionality. Thus, some of our customers have decided to go straight to 5G NR SA. Especially those targeting new verticals that want to tap into new 5G use cases requiring ultra-low latency and Edge computing. 5G NR SA will allow industrial verticals to benefit from the performance advantages claimed by 5G exponents.



- Two Sides of The Same Coin

There have been discussions on the pros and cons of these two 5G tracks, sometimes to the point of rebuffing one option for the other. But that should not be the case; it is not an “either or” selection between NSA and SA but rather a matter-of-time perspective. It all boils down to the specific business goals and requirements of the service provider. 

For service providers who are looking to deliver mainly high-speed connectivity to consumers with 5G-enabled devices already today, NSA mode makes the most sense, because it allows them to leverage their existing network assets rather than deploy a completely new end-to-end 5G network. 

However, for those who have their sights set on new services such as smart factories, a straight-up 5G wireless technology that is no longer dependent on an existing 4G network could make more sense. Considered as the ultimate 5G, Standalone NR –  coupled with cloud-native 5G Core – will provide better support for all use cases and unlock the power of the next-generation mobile technology. Thanks to network evolution we’re entering a new era of ultra-fast connectivity, the most rapid response times ever, and a whole host of opportunities for new solutions and services.


- 5G Architecture Options

Here’s a closer look at the two 5G architecture options in terms of their characteristics and the value they bring…

(A) Non-standalone 5G the facts:

  • Be first to launch 5G and gain technology and market leadership
  • Introduce new 5G spectrums to boost capacity and increase delivery efficiency
  • Maximizes the use of the installed LTE base
  • LTE anchor required for control plane communication and mobility management
  • 5G Evolved Packet Core
  • Provides early adopter with 5G-enabled devices
  • Enables video streaming, AR/VR, an immersive media experience
  • Opens up opportunities for new use cases such as Critical IoT

(B) Standalone 5G: the facts:

  • Target 5G architecture option
  • Simplified RAN and device architecture
  • New cloud-native 5G Core
  • Brings ultra-low latency
  • The only option to provide same 5G coverage for low band as legacy system
  • Supports advanced network-slicing functions
  • Facilitates a wider range of use cases for new devices


- Expanding Network Coverage – A Major Challenge

Despite the many advantages of standalone 5G, there is still a major challenge that cannot be underestimated. Due to limited 5G coverage in the mid-band, providing full 5G coverage may require the construction of many sites, which is very time-consuming and costly.  

Recognizing this, many vendors have introduced inter-band NR carrier aggregation, which is a software feature that can expand the coverage and capacity of 5G NR in mid- and high-frequency bands when combined with low-band NR. This will increase the speed indoors and in poorly covered areas.

Operators with a large amount of low-band spectrum that can be dedicated to 5G may migrate to SA for coverage reasons. If operators don’t have to free up 4G spectrum for 5G, the transition will be much easier, but it’s not simple yet. 


[More to come ...]


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