• Dean Anthony Gratton

5G RAN: The Principles of Network Functions Virtualization

I feel I am on sort of a radio access network (RAN) “roll,” with this being my third visit to the technology. In my quest to understand more, I want to take another, perhaps a final, opportunity to explain some of the differences between the various RAN offerings and place them in some broader context.

OpenRAN, cRAN and vRAN

Now, you might recall I began my journey in December last year, where I offered a glimpse into the history of the RAN in “A brief history of the radio access network,” and last month I explained more about the opportunities available through the O-RAN Alliance in “The O-RAN Alliance and its global community.” I hope these two columns have provided you with some foundation from which I can broaden my scope here to explain the various flavorings across the technology and its impact upon the core network.


You might also be aware that the RAN has received some attention over the last couple of years or so, due to the excitement surrounding 5G, that is, the next generation of cellular technology. In particular, we’ve seen the emergence of several new software algorithms and buzzwords, namely Open RAN, the O-RAN Alliance, virtual RAN (vRAN) and cloud RAN (cRAN). I won’t cover O-RAN here, since I covered that last month, but in this month’s column I would like to expand upon these other definitions a little further.


Let’s keep this network open …

When building a wireless network, most of the cost is related to the RAN component itself, where such cost can be as high as 80% of the total network. So, having an opportunity to reduce this expenditure will help increase profits for wireless operators when faced with the challenge of a changing business model, where there is increasing mobile traffic and a downturn in revenue streams.


With this in mind, the RAN interface should ordinarily be open as encouraged by the Third-Generation Partnership Program (3GPP) standards body, but in true competitive style, RAN deployments have largely been proprietary or closed by the individual vendors and, as such, the fundamental hardware components are specific to that given vendor, inhibiting other operators from exchanging their hardware with the vendor-specific component. Likewise, this vendor lock-in also inhibits the ability to provide software upgrades unless all the radio equipment is replaced.


Creating the perfect segue

Ideally, it would be more cost-effective if “vendor A,” for example, could keep their radio on the top of the tower, so no one in the future would have to change it. Similarly, keeping the standard commercial off-the-shelf (COTS) and baseband processing unit (BBU) at the base of the tower would allow “vendor B” to simply perform a software upgrade remotely. This is the philosophy behind Open RAN, which permits you to easily exchange software and hardware without the need to remove and replace anything.

Virtualized RAN promises to “intelligently” enhance capacity and will greatly reduce your costs whilst boosting the overall customer experience.

Now, cloud RAN or centralized RAN, is a cloud computing-based architecture that supports the current legacy cellular technology, that is, 2G, 3G and 4G, as well as supporting future generations such as 5G. With cRAN came along a new fronthaul interface (over fiber) as well as a new industry standard, namely The Common Public Radio Interface (CPRI). Most operators are assessing if baseband centralization will foster in lower capex as well as optimizing both operations and maintenance for the centralized site. Such benefits of a centralized RAN may include reduced opex where baseband units are now in a central location whilst offering better support for vRAN, which is a perfect segue into our next topic.

Virtualized baseband functions

With mobile connectivity booming, especially around data services, virtualized RAN is a natural evolutionary step in mobile networks. The new architecture promises to “intelligently” enhance capacity and will greatly reduce your costs whilst boosting the overall customer experience. The vRAN architecture offers the flexibility and scalability that is needed across the core network which, in turn, will continue to support future applications and services seamlessly.


In a highly competitive market, mobile operators are increasingly under pressure to satisfy customer demand and offer varied applications, or services, that differ or set themselves apart from their competitors. The vRAN architecture is wholly different to the evolved cRAN offering in that virtualized baseband functions are used across server hardware using the principles of NFV.


Until next time …

vRAN is, of course, pivotal in the success of 5G where, with the help of NFV, hardware-specific functions are now virtualized or software-based. This is a comparable evolution to the IT industry, where network hardware components were also virtualized – I discussed this some time ago in, “Network functions virtualization: 101”. The vRAN architecture benefits all operators providing cellular services to their consumers – keeping a generic hardware platform and, in turn, enabling open applications and interfaces to keep abreast of the latest changes to technology whilst satisfying future demand and expectations.


So, this is where your “keeping it all software-based” Dr. G signs off.



Originally published in Technically Speaking.

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