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Private 5G Networks – Technology, Architecture, and Deployment

private 5g

An overview of the private mobile networks was provided in our blog some time ago [see my earlier article: Private Mobile Networks and 5G Era]. Today, I’d like to go a bit more into the details and technical aspects of this topic. This article touches upon 3GPP features related to Private 5G Networks and various deployment options along with an analysis of the pros and cons.

Introduction

A private mobile network is a 5G or LTE system optimized (tailored) for a specific industrial or enterprise use case (like Industrial Internet of Things, IIoT), where specific requirements play an important role (like QoS, latency, mobility, security). There are different options for the implementation of those local/dedicated networks. They can be owned/managed by an MNO, an Enterprise itself, or a Venue Owner, and can utilize licensed, license-shared (using schemes like CBRS, LSA), or unlicensed (with schemes like LAA, NR-U) spectrum. What is important though, is the privacy aspect and carrier-grade security enabled by the 3GPP features. Figure 1, shows various high-level deployment options, ranging from completely standalone, through somehow integrated to the public network of an MNO, up to a network slice option, which is specific to 5G. In the later section, we’ll go more into the details.

private-mobile-networks-overview
Fig. 1. Private Mobile Networks: High Level Options

To decide which option suits a specific application, one shall answer several questions:

  • Who owns and manages the spectrum, radio network, transport, core network? – Is it the MNO, the venue owner, the enterprise, a third party?
  • Do you need a licensed, shared, or unlicensed spectrum? – Is having a licensed spectrum a tight requirement or is it enough to have unlicensed, as you don’t need to worry too much about interference.
  • What are your requirements regarding capabilities? What needs to be dedicated? – Do you have specific needs for QoS and high performing radio or dedicated resources?
  • Do you need it for a single local premise, multiple premises, or a wide area? – Maybe you have a single factory or multiple factories in different cities that have to be interconnected or can be treated as separate entities, or a smart grid application.

3GPP 5G Features for Private Mobile Networks

Let’s take a look at the 5G features defined by 3GPP [1] enabling it to be used in the private networks sector (see Figure 2):

  • First of all, as compared to Wi-Fi (being a typical wireless technology used in the enterprise sector as of now), mobile networks use carrier-grade security and privacy features, as well as well-defined mobility, all of which suit specific requirements for a given application (e.g. factory automation).
  • Another set of features that allow it to stand out (as compared to the previous generations, like GSM or UMTS) is the software-based core, virtualization, CP-UP split, and well-established centralized management including advanced radio resource management (RRM) and self-organizing networks (SON).
  • Yet another aspect is 5G-claimed flexibility realized by various spectrum access methods and high-performance features defined for use cases in the ultra-reliable and low latency (URLLC) class: with accompanied Time-Sensitive Networking (TSN) and high precision positioning serving as examples. This allows 5G to be applied for challenging services.
private-5g-dedicated-3gpp-features
Fig 2. Private 5G: Dedicated 3GPP Features

All this allows the private 5G to be considered as a good alternative to Wi-Fi or wired solutions in the private/vertical sector, due to 5G being 3GPP defined, flexible, scalable, and future-proof, with high-performing radio, optimized for local services.

What is a Non-Public Network?

One important aspect, shown in Fig. 2, is the so-called, NPN, or Non-Public Network, i.e. the 3GPP name for a Private Network. As per the standard definition, there are two versions of NPN, namely independent (Standalone NPN, SNPN) and integrated (Public Network Integrated NPN, PNI-NPN) [1]:

  • SNPN is operated by an NPN operator (and thus not rely on MNO), allows access to the public network (however, is treated as an untrusted network), and allows a UE to have a subscription to one or more NPNs.
  • PNI-NPN, on the contrary, is an NPN deployed with MNO support (e.g. using a dedicated spectrum or slice) and uses CAG (closed access group) to disallow other UEs (i.e. an NPN UE’s subscription includes CAG ID).

(BTW, isn’t the Non-Public Network a bit weird name to call a Private Network? :))

Private 5G Deployment Options

Now, getting back to the architectural aspects. Figure 3 shows three deployment options for a Private 5G Network (see also, e.g., [2]).

private-5g-options
Fig. 3. Private 5G Deployment Options

If we use nomenclature from the previous section, the top option (i.e., an independent private network) is SNPN, while the other two options (i.e. RAN and signaling shared, and a Network slice) are versions of PNI-NPN as given below.

  • an independent private network is a mobile network deployed at the enterprise, completely isolated from the public network provided by MNO. Nothing prevents the MNO to deploy such independent networks, but the important thing is, that those networks are not relying on and do not interact with the MNO’s large scale network. In such a case, the enterprise stores user and subscription databases locally. Also, the control of the network and data services are handled locally by the enterprise. Therefore, in this option, the network operates on a dedicated spectrum (or use unlicensed).
  • RAN and signaling shared option is where the services are handled locally within the enterprise, while the RAN (and spectrum) is shared with the public network. Network and user control is also handled by the MNO. Thus, the N2 interface is terminated at the 5GC within the public network domain.
  • In the Network slice option, the slicing concept introduced in the 5G standardization, is used to realize a virtual network for a specific application, which is logically separated from other virtual networks. In this implementation, resources are isolated such that the SLA for a specific enterprise is kept safe and does not interfere with other slices and vice versa.

The analysis of pros and cons of the above three options is provided in the table below.

TypeAdvantagesDisadvantages
Independent Private Network• complete isolation from public NWs
• independent QoS assurance
• secure/local data storage
• low/predictable latency – all components close by
• no monthly subscription charges for end-users
• high CAPEX for SW, HW, and license fees
• high spectrum cost or unlicensed with high interference
• need for skilled IT staff
RAN and signaling shared• licensed MNO spectrum (cheaper and less prone to interference)
• lower CAPEX
• MNO maintains the network with SLA
• secure/local data
• low/predictable latency – all components close by
• not completely isolated from MNO
• signaling dependent on MNO network (potential issues when loaded network)
• subscriber info stored in MNO databases
• monthly subscription charges for end-users or RAN usage
• need for trained IT staff (troubleshooting)
Network slice• logical separation from the public network
• licensed MNO spectrum
• lower CAPEX
• MNO maintains the network with SLA
• no physical separation from the public network
• dependency on MNO network for QoS
• higher latency
• subscriber info stored in MNO databases
• monthly subscription charges for end-users or RAN usage
• need for trained IT staff (troubleshooting)
Table: Private 5G Network Options – Pros and Cons

Please note that the above provides a non-exhaustive list of the deployment options. Those are rather representative cases to show various alternatives, but mixes and subversions are possible (see as an example [3]).

Challenges

The topic of private mobile networks poses quite a few challenges. There is a multitude of options by which such a network can be deployed as shown and discussed within this post. Also, there are many ways the spectrum can be accessed. Finally, there are many technical options and features within the 5G system itself to realize different use cases. That creates complexity and requires per-case discussion to make use of the technology in an efficient manner. There is definitely no “one-size-fits-all” approach to solve all verticals’ use cases.

Also, apart from the technological and deployment issues, there is an important aspect of language barriers between the actual use case/application and technology. As the target of private mobile networks is verticals sectors, which use case-specific language, which is not always fully understood by the technology people from the 3GPP world, there is a need for unification and alignment so that each party understands each other.

Finally, an inseparable element of the private mobile networks topic is integration. Integration on different levels between various technological components, spectrum assets, use case, requirements, applications, and language/nomenclature. There is also a need for private mobile network integrators, who can build a case-specific network.

All in all, if 5G is to be successful, it needs to be successful in the vertical/enterprise/industrial markets, which is realized by private mobile networks.

Note: if you’d like to watch my talk on this topic, see another post, with an embedded video recording from a conference 5G Core Summit – Cloud, Fog, Private 5G or go directly to the video on our youtube channel: 5G and Private Mobile Networks.

References

[1] 5G for Industry 4.0 (3gpp.org)

[2] 5G Non-Public Networks for Industrial Scenarios (White Paper) – zvei.org – Microsite (5g-acia.org)

[3] 7 Deployment Scenarios of Private 5G Networks | NETMANIAS

Author Bio

Marcin Dryjanski received his Ph.D. (with distinction) from the Poznan University of Technology in September 2019. Over the past 12 years, Marcin served as an R&D engineer and consultant, technical trainer, technical leader, advisor, and board member. Marcin has been involved in 5G design since 2012 when he was a work-package leader in the FP7 5GNOW project. Since 2018, he is a Senior IEEE Member. He is a co-author of many articles on 5G and LTE-Advanced Pro and a co-author of the book „From LTE to LTE-Advanced Pro and 5G” (M. Rahnema, M. Dryjanski, Artech House 2017). From October 2014 to October 2017, he was an external advisor at Huawei Technologies Sweden AB, working on algorithms and architecture of the RAN network for LTE-Advanced Pro and 5G systems.​ Marcin is co-founder of Grandmetric, where he served as a board member and wireless architect between 2015 and 2020. Currently, he serves as CEO and principal consultant at RIMEDO Labs.
You can reach Marcin at marcin.dryjanski@rimedolabs.com


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