Dean Ramsay is an analyst, consultant and writer with over 20 years’ experience in the telecoms industry. After a decade of building global B2B telco networks and software ecosystems, he has as an analyst written widely on topics such as 5G, network virtualisation, IoT and next generation operating models. In his role as Head of Research at Telecoms Tracker he is a trusted advisor to the world’s largest telecoms software companies.
Mobile network operators (MNOs) in the UK use a variety of different radio frequencies to transmit and receive data from their networks to our mobile devices, and while this is an extremely technical exercise the basic principles are relatively easy to understand. Using the lower frequency bands of the radio spectrum allow MNOs to transmit radio waves over very long distances, and they pass through obstacles such as buildings easily. However, the amount of data per second that can be sent over low frequency signals is low.
The opposite is true of using high frequency bands, much higher data transfer rates can be achieved, but the distances over which they can be broadcast are shorter and propagation through walls and trees becomes a problem. The connection your mobile device currently has uses a mix of higher and lower bands to provide an ‘always on’ connection with relatively fast data transfer.
One of the key promises of 5G is that MNOs will be able to provide hugely increased speed and capacity to end users over a mobile connection. The way they achieve this is by using additional bands in the much higher frequency radio spectrum and blending these with lower frequency bands.
Additionally, the MNOs are ‘densifying’ the mobile networks by building new macro cell sites and installing small cell sites all over the country, so at any time you will never be far from a 5G antenna.
What bands are being used now and which will be auctioned in future
Each operator will need to acquire a wide block of spectrum in different bands in order to provide the data throughput required for 5G. Several 5G bands have already been auctioned and more may follow in future:
Bands being used now
Sub 1GHz band: dubbed the ‘coverage layer’, will provide wide area and deep indoor coverage, and in Europe encompasses the 700MHz band. These frequencies travel over long distances and penetrate buildings well, but are limited in terms of capacity and therefore speed. They combine with the next band to enable operators to roll out 5G quickly and more cost-effectively. 80MHz of spectrum in the 700MHz band was auctioned to UK networks in March 2021.
1GHz-6GHz band: aka the ‘coverage and capacity layer’, relies on C-band spectrum around the 3.5GHz mark to deliver the best compromise between capacity and coverage. European regulators have identified the 3.4-3.8GHz band and plan to harmonise it to make it suitable for 5G. It will be the main frequency band for the launch of 5G. This is the main band currently being used for 5G, with the UK’s networks making heavy use of the 3.4GHz band, and Three additionally using spectrum in the 3.6-4GHz band. The UK’s networks have also cumulatively acquired 120MHz of spectrum in the 3.6-3.8GHz band as part of the second 5G auction, so this will also soon come into play.
Above 6GHz band: aka the ‘super data layer’, uses higher frequency millimetre-wave (mmWave) spectrum to deliver high data rates for specific use cases. Europe has agreed to harmonise frequencies in the 24.25-27.5GHz band, although it’s commonly referred to as the 26GHz band. It will be the key enabler of future 5G services and be critical to 5G networks. At the time of writing, this spectrum isn’t used by the UK’s networks, but that may change in future as explained below.
Bands being auctioned
At the time of writing (April 2021), the UK’s second 5G spectrum auction (covering spectrum in the 700MHz and 3.6-3.8GHz bands) recently concluded, and the four main networks have each secured spectrum from it.
While no subsequent spectrum auctions have been confirmed, Ofcom is known to be freeing up spectrum in the 8GHz and 26GHz bands, as well as the 1492-1517MHz band, the latter of which should be available by December 2022.
Ofcom is also looking into potentially opening up the 32GHz, 37-43.5GHz and 66-71GHz bands to mobile networks at some point in the future.
How much 5G spectrum do the UK’s networks have?
5G spectrum holdings
Following the second 5G spectrum auction (held in March 2021), the 5G spectrum holdings of each network are as shown in the chart above.
For the purposes of this chart we’re only counting relatively high frequency spectrum (in practice 3.4GHz and above) as 5G spectrum, as while all mobile spectrum can play a role in 5G networks, it’s generally this higher frequency spectrum that networks refer to as being fit for 5G.
As you can see, Three has by far the most, and that’s thanks in large part to its purchase of UK Broadband. Its 5G spectrum includes 20MHz of 3.4GHz spectrum, and 120MHz in the 3.6-4GHz range.
Vodafone, meanwhile, which has the second most, has 50MHz in the 3.4GHz band and 40MHz in the 3.6GHz band. EE and O2 each have both 40MHz in the 3.4GHz band and 40MHz in the 3.6GHz band.
If you were to include the 700MHz spectrum that was also auctioned, then Three and O2 have 20MHz of that, while EE has 40MHz, and Vodafone has none.
What is mmWave and what new mobile services will it enable?
The list of new services and revenue opportunities that will be enabled by the use of mmWave spectrum is large, with many of them being in non-traditional telco markets, such as smart city, automotive or industrial. For example, many trials are currently going on using mmWave combined with mobile edge computing to provide the connectivity to and between autonomous vehicles. This is an example of concepts that have been around for several years, but the 4G era of communication options have just not been powerful enough to ensure safety and excellent customer experience. 5G is enabling these products and services to finally come to market.
mmWave spectrum is highly desirable for 5G because there’s a lot of it and it can deliver very high data transfer rates. Cells can be located close to each other without causing interference, making them ideal for high capacity networks in specific locations.
In other words, using mmWave enables far higher speeds than lower frequency spectrum, so this is key to fulfilling the full potential of 5G.
The disadvantages of mmWave are that signals don’t travel as far as in lower spectrum bands and are unable to easily pass through physical objects like buildings or trees. They are also subject to other interferences, such as rain scattering the signal, system performance degraded by brightness, and atmospheric absorption, all of which contribute to the low range. mmWave frequency bands will therefore require many more antennas and antenna sites to overcome these shortcomings, and new technologies like Massive MIMO and beamforming will be key to unlocking the potential of these frequencies. mmWave will also be used in tandem with lower frequency bands to deliver both the coverage and capacity that 5G will require.
Inter-operator spectrum sharing and trading
In terms of operational efficiency, it is advantageous for MNOs to hold continuous spectrum bands rather than many narrow bands interspersed with other operators’ bands. We are seeing some instances of spectrum being traded between the MNOs so that they hold a contiguous block. Ofcom are trying to build as much planning for this as possible into the auction process, but there is also some swapping and changing after the fact.
In 2020, EE/BT requested approval from Ofcom to trade some of their 4G unpaired radio spectrum in the 2.6GHz band (between 2595-2620MHz) to O2. At present neither O2 nor Three UK own any of their own spectrum in the 2.6GHz band, so this kind of deal will become more prevalent as 5G is deployed at scale.
More recently we’ve seen O2 and Vodafone arrange to trade some of their spectrum so that O2 can obtain an 80MHz contiguous block, while Vodafone can bring its spectrum closer together.
It’s worth noting that Three has an even bigger 100MHz contiguous block, but this was arranged with Ofcom, rather than being the result of trading with another network.
During the 4G era there were some examples of spectrum sharing between competitors when it was advantageous for both parties, however this was not common practice. The expense of rolling out 5G combined with uncertain service revenues has led UK MNOs to take advantage of some of the spectrum sharing models built into the 5G specifications to drive down costs and boost efficiency.
5G Coverage Checker
Recent delays in 5G rollout
The classification of the Chinese equipment vendor Huawei as a ‘high risk vendor’ by the UK government in 2020 means that a large amount of that vendor’s equipment has to be removed from all 4G and 5G networks. While this unexpected turn of events has cost the UK MNOs some time in their original 5G rollout schedule, it has also been a good opportunity to revisit some of the technology used in the deployments, especially around dynamic spectrum sharing.
The replacement equipment is mostly coming from Ericsson and Nokia, who are both placing emphasis on the equipment and the software’s ability to dynamically use existing spectrum allocations for both 4G and 5G communication profiles. So while the Huawei scandal in the UK has delayed 5G and cost a great deal of additional CapEx, it has allowed MNOs to revisit their spectrum plans with the benefit of live network experience, which may be beneficial in the long run.
Auctioning of the new spectrum also suffered significant delays due to the long-running dispute over coverage obligations on the 700MHz band, which had to be settled via the £1bn industry-led Shared Rural Network (SRN) agreement. The SRN is Ofcom requiring the targeted sharing of existing masts and new masts in poorly-served rural areas, which aims to extend UK 4G geographic coverage to 95% by the end of 2025.
What’s next for 5G spectrum usage in the UK?
The future spectrum challenge for 5G operators in the UK is that this new generation of network technologies is being deployed alongside 4G LTE networks and not as an immediate replacement. This means that the available lower to mid frequency spectrum is mostly in use already, and while the LTE spectrum is being used by 5G, demand is still high. As such, MNOs and the regulator are constantly looking for reuse strategies for bands being used by the telecoms industry or elsewhere.
Some of the unlicensed spectrum or public broadcast bands may be made available for use in future years to complement the use of mmWave in the higher frequency bands. This is being investigated in the US, and the UK may well follow suit.
Useful reading: 5G Coverage and Networks