14 June 2022

While industry interest in millimetre wave spectrum for mobile has declined, it should not be dismissed. As Ofcom opens a consultation on enabling millimetre wave for new uses, Amit Nagpal, Partner at Aetha Consulting, considers the past, present and possible future of high band spectrum.

Millimetre wave (mmWave) spectrum is once again a talking point. Ofcom’s recent consultation ‘Enabling mmWave spectrum for new uses’ proposes to make a large amount of millimetre wave spectrum available across the 26 GHz and 40 GHz bands for use of mobile technology, including 5G.

Ofcom’s proposition

It’s an interesting proposition that brings some potentially knotty licensing problems to be resolved. Dividing the 26 GHz band into high demand and low demand areas, the proposal is to make citywide licences available on a first-come-first-served basis in ‘low density areas’ as well as in the lowest 850 MHz of the band in ‘high density areas’, whilst auctioning city/town-wide licences for the upper 2.4 GHz of the spectrum. For the 40 GHz band, Ofcom is consulting on options to make this available for mobile use, which is not currently supported by the existing licence terms, including varying or revoking existing licences to deploy mobile services in this band – or a combination of both. With the consultation ending in July this year and new use expected to be available by 2024, the outcome will be of keen interest to UK mobile operators but also watched closely by regulators and operators around the world, mindful of what the decision might mean for other countries.

The UK regulator’s proposal could pique renewed interest in millimetre wave which has waned elsewhere – it never quite delivered on its original promise despite its data speed allure. News from the US earlier this year of the release of Apple’s 2022 iPhone SE without mmWave 5G has been flagged as a signifier of the end of mmWave spectrum, despite it being championed by operators Verizon and AT&T. I’m not convinced this all adds up to the demise of mmWave – its absence in the iPhone SE aside, there are other factors driving the possible future of the high frequency band.

Challenges and solutions

Before looking ahead, it’s worth taking a moment to recall the emergence of mmWave for mobile in 2013 which came about because of the lack of mid-band spectrum options at the time. Touted as the solution to increasing volumes of traffic for its ability to transmit large amounts of data at speed, the high frequency band came with propagation characteristics that needed to be overcome – communication distances are short, attenuation levels are high, and the frequency doesn’t deal well with obstructions, struggling to pass through buildings. R&D focused on exploring potential solutions such as beamforming coupled with massive MIMO antennas but, while investment by a number of organisations and operators, including Qualcomm, Ericsson, Verizon and AT&T was significant, the economies of making mmWave work commercially remain challenging.

Europe changes direction of travel

Europe’s draft ‘Opinion on spectrum related aspects for next-generation wireless systems (5G)’ in 2016 took attention away from the high frequency when it identified 3.5GHz as the key pioneer 5G band. The rest of the world followed at pace – apart from the USA which remained the biggest proponent of mmWave due to a lack of free spectrum in the mid-band array. The US opportunity came in 2018 with a game-changing offer by satellite companies to open a portion of the coveted mid-band spectrum for terrestrial mobile use, leading to the C-band auction in early 2021.

With abundant availability of mid-band, the adoption of mmWave diminished. Only a limited number of mobile handsets currently support mmWave technology, and with few operators demanding mmWave, very few European countries met the legal requirement to make spectrum in the 26 GHz band available for mobile use. Further afield in the US, Verizon, which invested heavily in high frequency, re-announced its high-performing 5G Ultra Wideband network to now include mid-band spectrum. The mobile industry appears intent on acquiring even more mid-band spectrum which can be deployed on existing cell sites, and seems to have lost appetite for mmWave that requires the deployment of a new network topology of small cells. It’s a tight time for mobile operators not gaining any new revenues whilst carrying ever-increasing traffic making it impossible for them to invest in such a new network architecture.

One to watch

Despite the downturn in interest, I don’t believe the mmWave should be written off – in certain circumstances the high frequency band brings benefits. High density areas such as sport and music stadiums and transport hubs, where large numbers of people want to download and upload content, are ideal places for short wavelength. This also applies to countries where small cells have already been deployed by operators, such as Japan, because the additional investment required to utilise mmWave spectrum is moderate. It is also relevant in areas where broadband services are uneconomic to be provided by fibre all the way to the home/small business premises. In countries where wireline broadband services are costly, such as in the USA, fixed wireless access services using mmWave spectrum can be a viable competitor to fibre service provision – if mmWave networks can reach your home, they can provide impressive results – and in countries where existing wireline infrastructure is poor or limited, the mmWave can provide an effective complement to fibre and satellite solutions.

The key issue for mobile use will be the development of the handset ecosystem – when will we see the mmWave iPhone on sale all around the world and when will mmWave be in other mass-market smart phones? I don’t know when it will happen but I’m sure it will. Time will tell – and the outcome of Ofcom’s consultation is certainly interesting to watch in the meantime.