The past few years have featured several exciting success stories for Private 5G, particularly in the broadcasting sector. Companies such as Neutral Wireless, Cisco, and the BBC, aided by academic collaborators such as the University of Strathclyde’s Software Defined Radio lab (StrathSDR), have rolled out ambitious and ground-breaking deployments such as for HM King Charles III’s Coronation, or for elite global sporting events.
But if you’re coming to these stories late, you may be wondering what all the fuss is about. You might be asking yourself… “What is Private 5G?”.
What is Private 5G?
In a nutshell, a Private 5G network features most of the same component parts as a public 5G network. However, Private 5G networks are often deployed at a smaller scale, and with a different end goal in mind. Rather than providing ubiquitous 5G coverage to be shared amongst the general public, Private 5G instead focuses on delivering dedicated, high-performance connectivity for specific use cases.
Private 5G also comes with an inherent level of security. Just like a relevant SIM card is needed to access a particular public cellular network, the only devices able to attach to your Private 5G network are those which you have provided with SIM cards for secure authentication.
This means that rather than sharing network resources with several thousands of people (think of all those failed New Year’s Eve phone calls), your mission- and business-critical applications can rely on dedicated resources. And since you are in control of the network, you can also configure how those resources are allocated.
A Private 5G network can be tailored towards a specific use case, with the relevant communications resources configured for higher upload speeds or ultra-low latencies, depending on what is required. This flexibility can be particularly important for applications featuring video cameras or sensor data, where a focus on upload speeds is a priority (in contrast to public cellular networks that are configured to favour download traffic).
Private 5G Building Blocks
5G networks of course consist of several hardware and software components, with a wide variety of standardised interfaces and a lifetime’s supply of acronyms. But considered at a high level, Private 5G networks consist of just a few need-to-know building blocks.
- User Equipment (UE) refers to the end devices that will connect to the network via an attached SIM card. A UE will feature a 5G modem that allows the transmission and reception of 5G signals. Some examples of common UEs are smartphones, video/security cameras, or sensors.
- Antennas are used to transmit and receive radio-frequency (RF) 5G signals. 5G antennas can either be omni-directional or directional. Omni antennas will provide 360-degree coverage, whereas directional antennas will provide narrower coverage in a specific direction (often to greater distances). A 5G antenna will be connected to an associated radio head via RF cables.
- Radio Heads are 5G radio transceivers responsible for broadcasting the wireless RF signals that are transmitted over the 5G network via connected antennas. A radio head and antenna pair (and associated coverage area) is referred to as a 5G “cell”. In public networks, cells are usually deployed on top of tall masts at elevated site locations, or on city infrastructure. But this does not have to be the case with Private 5G. Radio heads are connected by fibre optic cables to a baseband unit, and this interconnect is often referred to as the “fronthaul” link.
- A Baseband Unit (BBU) generates/processes the signals that are transmitted/received by connected radio heads, translating useful data into radio signals and vice versa. In 5G terminology, a BBU can be referred to as a gNodeB, or gNB. A 5G network can consist of several BBUs, which must all be connected back to a single 5G core. Collectively, the portion of a 5G network containing the antennas, radio heads, and BBUs is referred to as the Radio Access Network, or the RAN.
- The 5G Core can be thought of as the brains behind a 5G network, and is responsible for device authentication, mobility management (as devices travel between cells), and connectivity to external networks. The connection between the BBU and the 5G Core can vary depending on the specific 5G architecture. In some cases (such as for smaller deployments), the BBU and 5G Core can be deployed on the same physical hardware. Otherwise, they can be connected via fibre optic cables, and this interconnect is often referred to as the “backhaul” link.
- Backhaul Connectivity (Optional) In the context of a Private 5G network, “backhaul” is one of those tricky terms that can mean several different things. Traditionally speaking, it refers to the BBU-to-5G-Core interconnect, as mentioned above. However, “backhaul” can also be used to refer to the connection between the 5G core and an external network – such as an organisation’s wider LAN (sometimes referred to as the network “edge”), or public internet. From this perspective, backhaul can be thought of as the “internet source” that UEs over a wider area can access wirelessly, via 5G. This can be provided via several options such as fibre or ethernet, point-to-point microwave, or LEO satellites.
- Access to 5G Spectrum. All 5G networks require a spectrum licence for legal transmission. Ofcom’s Shared Access Licence scheme, introduced in 2019, has allowed the UK to become a world leader in Private 5G innovation by allowing affordable access to the upper-n77 frequency band. The ONSIDE project looks to build on this foundation to make full use of the available spectrum, through improved accessibility to (and understanding of) Private 5G and exploring possible routes for quick and dynamic spectrum licensing.
All 5G networks will contain each of the above building blocks, in some fashion. But there can be significant differences in how each of these component parts is implemented.
To give a relevant example – a key area of development in recent years is the concept of software virtualisation. Traditionally, many of the aforementioned building blocks would exist as dedicated hardware implementations. However, virtualisation allows for the same functionality to be achieved in software, allowing for virtualised BBUs and 5G Cores to be deployed on high-performance server grade compute platforms.
Another important consideration is how all of these pieces fit together. Or, in other words, the network architecture.
Putting it all Together – Private 5G Network Architectures
Traditional RAN Architecture
A “traditional” 5G RAN architecture will be largely similar to the configuration illustrated in Figure 1. In this case, the network components are connected mostly as described above, with the BBU and the 5G Core existing on physically separate platforms. Whether these are implemented on dedicated hardware or as virtualised software implementations makes no difference to the architecture itself, but in the latter case this might also be referred to as a “virtualised RAN”, or vRAN.
In the above example, a cloud-based 5G core implementation is shown. This type of architecture is often desirable for large-scale or multi-site deployments – especially those deployments that need to be tightly coupled into existing IT and business management systems. Cloud-based 5G Cores (such as those offered by ON-SIDE partner Cisco) can offer an “as a service” delivery platform serving people, things, and places.
However, for smaller-scale (or pop-up) private deployments, there can be a benefit to deploying the 5G Core locally. Platforms such as Cisco’s Private 5G solution, or Neutral Wireless’s Private 5G Lomond NIB, can ensure local (edge) data can remain local. Access to a local 5G Core can remove any dependency on costly fibre runs back to organisational premises, or even public internet connectivity.
Consolidated RAN Architecture
In some cases – particularly for vRAN implementations – there is scope for various network components to be deployed on the same physical hardware, or within the same physical casing. This type of consolidated 5G RAN architecture often features what have become known as “Network-In-a-Box” (NIB) style products, such as the Neutral Wireless Lomond NIB.
An example of a NIB-based consolidated RAN architecture is illustrated in Figure 2. Note that this is just one example of a consolidated architecture, of which there are several variations. Other examples could include cloud-based 5G Cores, or radio heads with integrated antennas (a practice that is somewhat common for low-power, indoor radio units).
At a glance, it should be obvious that this type of architecture can result in drastically simplified deployments, as illustrated in Figure 3. As such, consolidated 5G network architectures are perhaps inherently more suited to pop-up style deployments such as for events, festivals, or news gathering broadcasts.
ORAN Architecture
Open RAN, or ORAN, is a proposed non-proprietary RAN architecture that seeks to diversify the 5G network supply chain through the definition and promotion of standardised interfaces. The ultimate goal of ORAN is to enable complete interoperability of 5G networking components from different vendors.
The ORAN architecture (illustrated in Figure 4) seeks to split the functionality of the BBU, and in some cases to offload some of the responsibilities of the BBU to the radio heads (referred to as Remote Radio Units or RRUs in ORAN nomenclature). In ORAN, the BBU is split into two separate units known as the Distributed Unit (DU) and the Centralised Unit (CU). This necessitates a new interconnect between the DU and CU, which is referred to as the “mid-haul” link.
There are several numbered split architectures within ORAN, which correspond to different areas of split responsibilities across the RRU, DU, and CU. Within the ON-SIDE project, the BBC, Cisco, Neutral Wireless, and the University of Strathclyde are exploring the Split 7.2 architecture, and are comparing the achievable performance to traditional and consolidated network implementations.
So… Which is Best?
The honest answer, and the only answer that can provide an end customer with the best performance, is that “it depends”. Different architectures of course come with different benefits and drawbacks, and the extent to which these will be beneficial or costly depends on the targeted use cases.
A driving force behind the ON-SIDE project is the desire to develop Private 5G solutions that are more accessible to a wider range of end-users. By engaging with key stakeholders in various sectors, the ON-SIDE consortium aims to increase adoption rates by understanding and addressing the challenges and requirements of specific customers.
The flexibility of Private 5G and its associated architectures can be a powerful tool in tailoring a network to meet those requirements. By thinking of a Private 5G network as a series of building blocks rather than a singular entity, bespoke deployments can be undertaken to provide optimal value and performance.
These could involve portable, all-in-one Network-In-a-Box style solutions or disaggregated networks that can take advantage of existing fibre infrastructure in locations such as TV studios, sports stadia, or outside broadcast compounds. Even battery-powered networks are a possibility – allowing for robust connectivity at remote locations, or those that are difficult to access.
In any case, the key is that the use case should inform the architecture, rather than vice-versa. This is the approach taken by the ON-SIDE partners: working together to understand the key operational and business requirements of use case stakeholders, before designing tailored, technical solutions to meet those needs.