26 GHz – A radical approach to licensing in higher frequencies to increase spectrum efficiency

A new study carried out by Real Wireless on behalf of the UK Spectrum Policy Forum (UK SPF) proposes a radical approach to licensing the 26 GHz band. The report proposes a hybrid licensing approach i.e. exclusive access to MNOs with some flexibility to share in the high demand areas and a flexible first-come first-served sharing approach would be adopted in the rest of the country.

Looking at 26 GHz spectrum: demand, delays and a novel approached to spectrum allocation
2020 was challenging in every respect and even Europe’s spectrum auctions felt the pain. The European Electronic Communications Code (ECCC) directive specifies the availability of at least 1 GHz of the 26 GHz band by the end of December 2020. In reality, only a few countries achieved this objective, with the main reasons stated as lower than expected demand, uncertainty regarding the business case and a lack of harmonisation for the award mechanisms– something regulators are working on.

The 26 GHz band is capable of delivering fibre-like speeds with extremely low latency, but the high propagation loss poses a challenge to achieve wide area coverage compared to lower spectrum bands. This clearly represents a challenge for the UK regulator, Ofcom, which is tasked with licensing this band as part of their commitment to the ECCC directive. While this spectrum band is accessible for indoor deployments under the Shared License Access scheme in the UK, the need to release the spectrum for outdoor use is what predominantly remains unfulfilled.

For the UK SPF study we went back to basics, establishing a model to demonstrate geographically where the 26 GHz spectrum was most likely to be used and to generate a series of recommendations to increase spectrum efficiency.

Typically, and in the case of the UK, licensing approaches for spectrum allocated for mobile have been framed in a national context, with incumbent MNOs acquiring the spectrum to deliver mobile services. The UK is an interesting case as, geographically speaking, it’s not a large country/area. This means that, historically at least, national licensing has made good business sense. But due to the specific characteristics of the 26 GHz band, we argued that a national approach to licensing isn’t necessarily the best option from a spectrum utilisation point of view.

The very high propagation loss means that the coverage on this band from existing cell sites and even after site densification would only be a small percentage of the land mass. There are technological features that can mitigate this to a certain extent, but comparatively, the area of coverage would be significantly lower than other mobile bands currently used. Furthermore, the amount of bandwidth available with the spectrum is noticeably higher – over 2 GHz of bandwidth compared with several 100s of MHz in the mid band and less than 100 MHz available in other lower frequency bands. These two characteristics make a national licensing model inefficient.

An operator would be extremely unlikely to deploy this band everywhere – it’s a high- capacity band better suited for use in already congested areas in the network to provide capacity relief. Therefore in the majority of the country, this additional capacity isn’t needed, as the level of demand can be managed by existing spectrum bands. Additionally, given the high propagation loss, providing national coverage with this band would require a disproportionately high number of cell sites, resulting in significantly increased costs to deploy such a network.

Demand map illustrating 45% of data consumption in the UK

Demand zones
By analysing mobile data use across the country, our study first identified high and low demand zones. In high demand zones, 26 GHz spectrum could be deployed as capacity relief, when the networks become congested. In lower demand areas, the MNOs may choose not to deploy the 26 GHz spectrum, as there simply isn’t sufficient demand to justify the costs of deploying and managing it.

But the spectrum still has high value. As a harmonised and standardised band, a growing number of devices and infrastructure equipment are being designed and manufactured that are intended to be compatible with this band. Harmonisation gives stability and confidence in a spectrum band and encourages OEMs to invest in the design and manufacture of devices that use it. So, while the band may not be fully utilised by MNOs, there are numerous other users or uses to which it could be beneficially applied.

In order to first define the zones of high and low demand, we used data supplied by Tutela to determine current mobile broadband demand levels across the country (see figure) and therefore create a methodology to identify areas most likely to suffer congestion. These areas are where MNOs would most benefit from deploying the band. Interestingly we found that “1% of the UK land area (i.e. 2,425 km2) corresponds to 45% of total data consumption in the UK”.

Efficient spectrum use
Once the high demand zones were identified, we set to work determining how to improve spectrum efficiency. Building on the framework initially proposed by the UK SPF, our approach provides MNOs with some degree of flexibility on band use, using their maximum allocation when needed, and returning unused bandwidth to a ‘pool’ when not needed and making it available for use by other operators experiencing higher congestion. In doing this, the spectrum can be used much more efficiently than if it was allocated to MNOs exclusively without any flexibility and provides a guaranteed minimum level of access, topped up by what is called the ‘club spectrum’ when available. This approach provides an opportunity to dynamically maximise the spectrum efficiency according to fluctuating demand levels.

For low demand zones, any spectrum user could use the available spectrum on a first come, first served basis, and other service providers and MNOs can share available spectrum according to pre-determined limits.

Enabling efficient use of spectrum is a priority for Ofcom and many regulators – our findings should significantly move the dial in this respect. A globally harmonised spectrum band serving an ecosystem that’s beginning to mature, gives any service provider, system integrator and end user that wants to deploy services the opportunity to do so.

The risk of business as usual
Under traditional national licensing models, spectrum can’t be used by anyone other than the MNOs which acquire the spectrum. It is also near impossible for newcomers to compete with the incumbents. Facilitating smaller entities to offer services using this globally harmonised band is a big step towards supporting government policy on digital transformation. The biggest single barrier for alternative service providers is access to spectrum. The approach proposed by our report overcome this barrier and encourages diversity in the market.

Regulatory implications
From the start, the aim of this project was to investigate novel approaches to licensing in higher frequencies; something brand new for the UK, levelling the playing field for new players, while not limiting the spectrum availability for incumbent MNOs. There is, however, a lot more work needed to move from ideas and proposals to successful take up by the market. Through this process, we’ve developed high level principles that can be used to tailor a framework for other regions and other regulators to take account of national localisation factors.

Looking at the distinct and unique demand characteristics for the UK has shown that every country needs a bespoke approach and potentially significantly different adjustments to the model. These characteristics will change over time too as new build developments such as housing, industry etc. changes the demand scenario.

The analysis, modelling and understanding developed in this project puts Real Wireless in a strong position to assess demand and propose principles or licensing models for other regulators around the world. The frameworks we have developed is based on expert independent knowledge and insight as well as complex engineering analysis to determine the impact of interference from base stations and recommending separation distances to maximise efficiency and maintain quality of service provision.

The novel, radical approach we have developed for this pioneer band uses key high-level principles that are unique to the UK but can be applied with further research and consultancy to other countries and regions. As part of the project, we also secured buy-in from MNOs that the approach proposed would be acceptable to their business models.

That level of confidence and certainty, underpinning comprehensive recommendations are something you only get from truly independent wireless experts.