Not so long ago, the term used to describe how spectrum was divvied up was “beauty contest.” However, things have moved on since the days of pageantry.
Beginning with the advent of 3G, spectrum has been allocated by auction — with the big mobile operators typically landing the highest bids. This has largely remained the status quo for the past two decade or more. But a few years after the introduction of auctions, TV broadcasting started switching from analogue to digital, people working within the telecoms space were coming to the realisation that the switch away from analogue would be freeing up a lot of frequencies.
The question was posed: could these unused frequency bands be opened up for other uses? ‘TV White Space’, as it became known, didn’t happen exactly as evangelists were hoping. But the seed of the idea was planted. And, over time, new initiatives, like CBRS — or Citizens Broadband Radio Service — would sprout, and make use of unused spectrum.
The concept of shared spectrum is now well rooted, and the UK is a global leader in efforts to improve access to lesser used bands. Since 2019, Ofcom has offered shared access licences, making spectrum access possible on a shared basis, in different geographical areas. Innovation projects across the country have backed up the enthusiasm of those early spectrum sharing advocates.
But the system as it currently operates is still a work in progress.
Room for improvement
Whichever spectrum is allocated, either shared or auctioned, the core aim remains the same: providing clear access, and avoiding those making use of different bands disrupting each other’s operations.
For this reason, accessing shared spectrum requires a shared access licence. Applicants for these licences can wait for up to six weeks for their claim to be processed. If an application is accepted, a small fee is due — and then Ofcom will send through the licence.
Needless to say, there will be many instances in which a prospective network operator will not have a full six weeks’ notice in which to file a licence request. (And even this timing doesn’t account for the days or weeks required to prepare an application, which will take longer for those unfamiliar with the process).
Aside from the time frame, difficulties can arise through the way in which Ofcom assesses the risk of interference between shared licence holders and existing networks. The regulator, with some good reason, tends to take a conservative stance on network disruption risks.
But the reality is that the current licensing regime has been based on static networks. Today, our demands and expectations of connectivity are far more dynamic.
At ON-SIDE we are working — in close collaboration with Ofcom — to explore ways of injecting greater agility into the allocation process, while maintaining the integrity of network operations. The 3.8-4.2GHz range is the focus of the project.
Since Ofcom is an evidence-based regulator, it will be important to provide practical, real-world demonstrations and measurement of our proposed approaches.
Hardware + software
Our project convenes around two strands — split broadly down the lines of hardware and software solutions.
On the hardware side, we are developing new 5G radio units which can perform real-time continuous spectrum sensing alongside their primary transmit and receive functions. These devices will both provide regulators with a clear picture of spectrum usage levels in specific locations, and bolster efforts to build intelligent spectrum coordination systems.
Our software efforts are focused on the creation of an intelligent spectrum management system. This system will allow spectrum usage to be managed and coordinated across multiple private networks operating within shared access spectrum — maximising the use potential of these frequency bands.
Our build follows Open RAN principles, in order that the resulting software system can continue to be upgraded over time. This system represents the first step towards a longer-term stretch goal — beyond the temporal limits of the ON-SIDE project. That is, to produce a full automated, adaptive spectrum access system for future wireless networks.
Reflective of the way in which connectivity underpins so many aspects and arenas of our modern world, the ON-SIDE project is running trials everywhere from sports stadia, to manufacturing plants, ports, airports, and broadcast studios.
By the time our project draws to a close in Spring 2025, we hope to have viable proofs of concept to demonstrate, interest from Ofcom in taking the work forward with serious consideration — and, related to both of these things, a stack of data that corroborates our theories on how to unlock the power of private 5G.
In other words, our work will enable that seed of shared spectrum — first planted all those years ago — to blossom.