Ofcom unsure of how to release spectrum for 5G

5G may disrupt the way Ofcom has traditionally released spectrum, and could bring about a new method of licensing the spectrum that underpins mobile services.

Speaking at Cambridge Wireless’ Future of Wireless conference, Joe Butler, Director of Technology Policy, Ofcom, said that the arrival of 5G, and the release of new frequencies to support that, was giving the regulator plenty to think about.

Chief amongst Ofcoms concerns is whether to license large bandwidths in parcels of 5Mhz or 10MHz bands as it currently is used to, or to invoke some new mechanism to enable operators to share large chunks of new spectrum. Many think that the economics of 5G will require far more active spectrum sharing than the industry has currently seen.

Butler said, “If what is required is 200MHz made available to be shared between all the operators in a certain way, it being detailed in 10MHz chunks might not be the right thing to do. We would be relying on the secondary trading market – so it would be in the gift of operators who purchased that spectrum to do something different and come back to Ofcom and change the rights to the spectrum – and that could happen.”

Another concern Butler expressed was whether it was even appropriate to license some higher mmWave bands, or apply very light licensing. Technology advances, propagation characteristics, directional antennas, SON, all mean the risk of interference decreases at these higher bands.

Butler added that the use of spectrum may also have an impact. Mobile broadband has very different requirements to vehicle to vehicle, for instance. How will Ofcom license around that?

“There’s not enough information to answer that question right now but it is certainly something we need to be thinking about,” he said. “We need better information about how well 5G will manage interference and sharing, and what sort of apps is it going to be used for.”

Butler added that there are also questions about what Ofcom does in very high bands above 100GHz.

“We can see technology starting to come through quickly north of 100GHz that pragmatically could be used within ten years or so. So the approach to do what we have always done seems easy to follow but not necessarily right for the longer term. Otherwise if we allocate in very detailed slices and chunks, it then very difficult to change and find new spectrum. 100GHz and up [poses] real questions in innovation – would making those sorts of frequencies exempt from licensing bring innovation or change the commercial opportunities in a negative way?”

What Butler was more certain about is that regulators must move for global harmonisation in Sub 6 GHz (under discussion in October at WRC-15) and mmWave bands (likely to be harmonised at WRC-19, just before predicted commercialisation of 5G). It’s not enough just to go to the ITU and ask for spectrum between 60 and 100GHz – that is likely to have “adverse outcomes” he said. To that end Ofcom has identified certain bands that it thinks are more easy to use between 30-100GHz, and also a series of candidate bands from 4GHz to 6GHz.