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20 March 2020

Flexible spectrum usage will be essential to deliver 5G’s economic potential

While the COVID-19 outbreak threatens to slow down or halt activity in many industries, in 5G it may prove to be a stimulus as more people become reliant on their networks to keep working and socializing.

But while governments, employers and vendors are already talking about 5G’s potential to change the way business is conducted, even after the crisis is over, many of their visions will be impossible to realize without access to more spectrum, on a more flexible basis, than many regulators currently envisage, in the short term at least.

It seems likely that 5G will be deployed by a far greater diversity of operators, including enterprise providers, wholesalers and neutral hosts, in order to share the cost burden and ensure the new networks are tailored to the needs of different industries. And if techniques like holographic conferencing are really to replace the face-to-face meeting, a great deal more bandwidth will need to be opened up in short order.

Some regulators are clinging to old ways, or moving slowly through the consultation processes to adopt new ones. But while we can question whether those processes will prove fit for purpose for much longer, at least they are happening in more and more countries, and with more flexible and innovative approaches to spectrum in mind.

Spectrum sharing – a middle way between exclusive licences and the unpredictable quality of service of unlicensed – will be fundamental to the new 5G models, allowing specialist operators to offer high quality services without having to raise billions of dollars for spectrum licences. It will also enable many bands that have incumbent users to be opened up for secondary services, without quite as much political in-fighting or drawn-out processes as we saw in the USA’s repurposing of the 600 MHz broadcast spectrum for cellular. Similar disputes have delayed, and sometimes threatened to derail, the process of opening up the C-band satellite spectrum for 5G.

The lessons from the CBRS experiment – a multi-tiered approach to sharing the 3.5 GHz federal band – will not be fully learned for two or three years, once licences for the priority access tier are auctioned, and the nature of the services in both that tier, and the unlicensed one, become clear. But many of the platforms, tests and trials that have gone into making CBRS the most-watched sharing system in the world can be repurposed immediately to make it easier to allow wireless broadband services into new bands, including the USA’s 6 GHz ‘WiFi extension’ spectrum, and even its 4.9 GHz public safety allocation.

C-band and CBRS are vital to the USA’s 5G efforts because its operators have so far, with the exception of Sprint, lacked midband airwaves, in which MNOs in most other markets have launched first. The common approach to 5G is to build out capacity where it is needed, while keeping 4G as the coverage network for the time being. For this purpose, midband spectrum such as 3.5 GHz allows for high levels of capacity without the ultra-short range and engineering complexities of the higher, millimeter wave bands such as 26 GHz, 28 GHz and 39 GHz.

The US operators have been forced to move up to mmWave before economics would normally have dictated it, but they will be accumulating valuable knowledge in how to harness these challenging frequencies cost-effectively, and the recently concluded mmWave Auction 103 was by far the most competitive of the three held so far, indicating rising interest in these bands.

At the other end of the spectrum, T-Mobile USA was the main buyer of the 600 MHz broadcast airwaves, and has been unique in building out 5G on a coverage basis first. Before it is able to add Sprint’s 2.5 GHz assets to its network, once their merger is finalized, it is focusing on making the most of the limited capacity of its sub-GHz spectrum while implementing a few mmWave hotspots too. In response to the COVID-19 epidemic, it has also come up with a scheme to aggregate 600 MHz spectrum from other providers, such as Dish, with its own, on a temporary basis, to help deliver more bandwidth to workers forced to work at home.

This may be the first of many ways in which the pandemic crisis stimulates new thinking about how networks and spectrum can be shared and used more efficiently to maximize 5G capacity, affordability and overall economic value. Adherence to owner-economics and single-network operations has characterized the cellular industry until recently, but this approach is gradually being set aside in favor of greater sharing and more flexible ownership models, forced by the sheer cost of 5G, and possibly accelerated by the current crisis.

And new technologies are emerging to make this easier – from spectrum access systems such as Federated Wireless’s, to ADVA’s new solution for harnessing underused optical spectrum, to end-to-end slicing engines that can aggregate and re-aggregate resources in many spectrum bands and technologies, and across wireless, wireline and compute.

All these advances will create a very different spectrum foundation for future waves of 5G. Progress may be gradual in this first phase of the new cellular network, but by the second half of the decade, we expect 5G policy and spectrum usage to be looking very different from the norms of the 4G era.