Sorting spectrum – the challenges allocating and managing 700MHz in the UK

A recent Westminster eForum Keynote Seminar on the possible use of 700MHz spectrum in the UK looked at the challenges of moving DTT and PMSE users and whether some spectrum will be saved for the public safety community

Sorting spectrum – the challenges allocating and managing 700MHz in the UK


Earlier this year, the International Telecommunication Union (ITU) – the UN body which allocates global radio spectrum and satellite orbits - provisionally decided to reallocate the 700MHz spectrum band to mobile services in the EMEA region. 

The move would bring the EMEA region into alignment with North America and much of the Asia Pacific region, which have already allocated 700MHz spectrum for mobile. The decision is likely to be ratified at the next major ITU meeting in 2015.

Clearly global harmonisation of spectrum brings many advantages, especially for mobile device manufacturers, allowing them able to tap into larger economies of scale, as well as facilitating easier international roaming for consumers. 

However, 700MHz spectrum in many parts of Europe, including the UK, is currently allocated to digital terrestrial television (DTT) and for programme making special events (PMSE) users (radio microphones for concerts and outdoor events, for example). 

These users would have to be moved and alternative spectrum found for them. In the UK, the most obvious frequency would be the 600MHz band, which is currently free after being recently cleared of analogue TV. 

Westminster eForum Keynote Seminar (7 December 2012): ‘UK spectrum management challenges – meeting the demands of tomorrow’s technology’

The discussion on the issues surrounding the reallocation of 700MHz frequency at The Westminster eForum was opened by Charles Constable, MD, Digital Platforms Division at Arqiva, who looked at the challenges of moving DTT providers yet again following the shift from 800MHz.

Constable asked: ‘Is there room for increased mobile data and digital TV, such as Freeview, YouView and BT Vision? We have to make sure the answer is yes. Freeview is at the heart of British TV and you undermine it at your peril. There is no TV Plan B – nothing else does what Freeview does. So, we must have a strategy that incentivises everyone with the costs and benefits fairly apportioned.’

The UK TV industry has just gone through a major digital switchover to prepare for the auction of 800MHz and 2.6GHz spectrum for mobile. Constable conceded that the reallocation of 700MHz looks inevitable, but warned: ‘Re-engineering Freeview to squash it into less space took years to plan and execute, so if we are going to do it again we need to start planning now. There is still a lot of work on 800MHz to be done. Clearing the 700MHz band may be even more disruptive, so it needs planning and sufficient funding.’

Constable pointed out that Freeview is on 12 million primary TV sets in 2012 (up by one million on 2011) so it is growing – making it the UK’s largest broadcasting platform. It is in 98% of homes and is free at the point of consumption. 

The main alternative to the Freeview model of distribution TV content is the use of all-IP TV broadcasting. But Constable said IPTV networks are not in a position to replace Freeview until 2030, according to Ofcom – a view he agreed with. ‘There are real challenges for a full IP model for TV,’ said Constable. He cited an unverified industry source who suggested that if the BBC had transmitted its Olympic 2012 coverage via IP only, it would have cost it the entire TV licence fee (c.£3bn plus). 

‘If the UK is to reap the benefits of 5G it needs to plan now. The strategy needs to be carefully planned, fully funded and the broadcasters’ costs of moving paid for,’ concluded Constable.

The next steps for 700MHz

Steve Ungar, group director, strategy, chief economist and technology at Ofcom, highlighted why more spectrum is required for mobile services. ‘Mobile traffic more than doubled per Sim card in 2012 and that doubling is expected to continue.’

But he said that DTT and PMSE need protecting. However, he asked: ‘Will IPTV video on demand (VoD) take over from terrestrial TV?’ Ungar believes that the current offerings are complimentary and in the near future are likely to be delivered via hybrid platforms. He also made the point that technology is helping to find ways to get more out of existing spectrum. 

For instance, DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial), which transmits compressed digital audio, video, and other data in ‘physical layer pipes’ using OFDM modulation with concatenated channel coding and interleaving, offers a higher bit rate than its predecessor DVB-T, making it a suitable for carrying HDTV signals on the terrestrial TV channels (such as Freeview HD in the UK). Similarly, various ways are being found to make more efficient use of existing mobile phone spectrum.

Nonetheless, Ungar said that post-2018, it is highly likely that the 600MHz band will be used for DTT, while PMSE will be interleaved with the TV channels or use other White Space. He added that the hope was that during the period up to 2018, more DTT will be broadcast in high definition using DVB-T2 and that more TVs would be DVB-T2-enabled. 

He added that work could also be done to ensure that new aerials being installed were able to receive TV signals in the future use bands. Devices would also need to be resistant to interference.

Ofcom to run a 700MHz work stream for professional services

Replying to a question from Tim Cull, business radio coordinator at the Federation of Communication Services, Ungar revealed that Ofcom would be running a work stream looking at the possibility of providing some 700MHz spectrum for professional services, including the emergency services and critical national infrastructure such as railways, power, oil and gas and other utilities. But whether that would be provided on a dedicated private network or some form of network sharing is open to question, Ungar said.

Staking a claim to 700MHz

Professor Simon Saunders, independent wireless technologist, Real Wireless considered the question of what role the 700MHz spectrum would play in the future as regards mobile capacity. He said that growth of mobile traffic is a given, but that no one really knows what the level of demand will be – estimates vary widely.

He asked whether it was a case of more capacity being needed or making better use of existing spectrum to meet this expected growth in demand for mobile services. The latter can be achieved through new technology helping to optimise the use of existing spectrum, along with the refarming existing spectrum, such as 2G, to help manage data growth.

He presented a chart with all the existing and potential spectrum available and pointed out that in the wider scheme of things the 700MHz band does not account ‘for much in the full mobile spectrum picture’. He said that to provide spectral efficiency more antennas would be needed on base stations and on devices – this adds to the costs and said questions would have to be asked as to whether that additional cost was worth the benefits.

2020 mobile capacity crunch

Saunders also showed a model of future growth, which argues that if 700MHz is not made available for mobile services, then there will almost certainly be a capacity ‘crunch’ in the early 2020s. At that point, it becomes very expensive for mobile operators to increase the efficiency of their existing spectrum holdings incrementally.

However, if 700MHz is available by 2018, then the cost of operating mobile networks reduces substantially, according to Saunders.

Richard Lindsay-Davies, CEO, Digital TV Group, said that DTT uses spectrum very efficiently. ‘We are very adept at managing migration from one band to another. We bridge broadcast and consumer technology (the Group helps manage set top boxes etc). The recent digital switchover was not easy; there was a lot of work done behind the scenes, money provided and so on.’

He warned that playing around with the nation’s favourite TV channel (Freeview) was dangerous, but that DTT companies were not Luddites and recognised that the demand for mobile services had to be met. 

But, reiterating Charles Constable’s earlier point, he said that a future digital switchover must be planned for very early in the process. ‘We can build on DTT’s inherent properties and make more of them. DTT has a very significant penetration of not just primary TVs in households, but also second and third TVs because of cable and satellite.’

He said that dynamic use of spectrum, such as TV White Space, should be looked at to provide additional services – but again warned that the whole process must be well managed.

Kate Miller, partner, business acceleration EMEA, Alcatel-Lucent, said that mobile is already a TV distribution business (if not an economically viable one yet). She said that Bell Labs (part of A-L) is predicting mobile data growth of  x 30-60, so will allocating 700MHz spectrum to mobile operators be enough to cope with traffic growth of this magnitude? 

Miller cited a number of ways to help manage data traffic: 50% of data traffic is done at home, so maybe this can be offloaded to home Wi-Fi; provide more cell sites to cope with increased density; delay less high priority traffic; and use more efficient techniques to manage capacity.

But even with all this combined, Miller said that still leaves 5 x growth not accommodated by any of the above solutions – ‘so, yes, we will still need more spectrum’.

Andrew Lillywhite, chief engineer, Sennheiser and spokesperson for the British Entertainment Industry Radio Group, spoke on behalf of the Programme Making Special Events (PMSE) community. He said that PMSE is currently interleaved in the 700MHz UHF band with DTT, so that if it is shifted to the 600MHz band there will be less TV White Space available [as DTT itself will be further squeezed to fit into the 600MHz frequency].

‘Radio microphones have been moved out of the 800MHz band and re-assigned to the 700MHz band and this has cost users to make the investment,’ said Lillywhite. ‘They are now being told that they can go to the 600MHz band but on six month rolling contracts – who will invest with that kind of uncertainty hanging over them?’ he queried.

‘Live events are a growth sector, but we can’t predict what that growth will be,’ said Lillywhite. He cited the 2012 Olympics, where the organisers estimated that 350 roving microphones would be needed; the actual number was 1,654.

Lillywhite added that PMSE is not just for entertainment and sporting events, it is widely used for sales conferences, political conferences – the Westminster eForum itself was using roving mics, - and it is also used in universities and schools. 

He acknowledged that Channel 38 [which uses the frequency range 606-614 MHz and is currently shared with radio astronomy – users apply for a UK Wireless Microphone Licence] is allocated to this, but he said it does not provide nearly enough capacity – hence the use of TV White Space to interleave PMSE. 

Lillywhite concluded with a plea not to relegate PMSE to an afterthought in the planning for 600MHz. ‘I think it is time not to just slot PMSE in as an afterthought, but look at providing a harmonised band for it.’

International experience and implications for the UK

Dr Chris Doyle, founder, Apex Economics and principal fellow, Dept of Economics, University of Warwick began by asking whether the margin achieved by building ever more capacity to provide broadband for everyone, including rural communities, was worth the return.

‘If you look at the nature of the traffic, a substantial amount of it is ‘trivial entertainment’; e.g. 1 billion photos are uploaded everyday to the Internet via the 5 billion handsets worldwide. So, is it worth finding the extra capacity to handle that traffic when mobile operator ARPU is diminishing? Can we control this via the pricing, rather than just paying billions to invest in infrastructure to meet the growth in demand?’ he asked.

Doyle noted that in the future users will probably have to get used to paying more or having their data plans capped. 

Beyond 700MHz: meeting the UK’s future spectrum demands

James Britton, executive director, equity research, Nomura argued that the investment perspective was key, as without strong financial returns what is the incentive for telcos to make the investment in 700MHz spectrum? 

He pointed out that European telcos are currently underperforming by 20%, while European mobile revenues have declined by more than 6% (although the UK is performing slightly better).

‘I suggest that the demand for data has not really taken off, which is putting the investment by telcos at risk,’ said Britton. ‘I’d argue that the telcos have plenty to do to stimulate demand for data. Telcos are now more confident of the resilience of their networks, so they are relaxing data caps to an extent. 

‘They face very strong pressure to monetise, but the telcos are putting the emphasis on selling the technology, rather than providing a good user experience, which would encourage subscribers to use more data and then the telcos can gradually move them up the data tiers,’ said Britton.

He concluded by saying that mobile returns are under pressure and that 10 years out, they may be down by 50%, which may jeopardise making investment in the 700MHz band a success.

Andrew Stirling, project director, Cambridge White Spaces, provided an outline of the recent White Spaces trial in Cambridge, the largest in the world so far, involving 17 companies. 

A white space device uses gaps in radio spectrum, called ‘white spaces’, which exist in between frequency bands (usually to prevent interference between bands) that have been reserved for TV broadcasting. Use of these white spaces would allow devices to transmit and receive wireless signals for applications such as broadband access for rural communities, enhanced Wi-Fi or machine-to-machine (M2M) networks. 

Stirling suggested that access to White Space could be provided by pooling spectrum in a ‘superhighway’ and storing availability and coverage details in a database. Stirling said work would need to be done to ensure that some users who need priority access were provided for, but dynamic access would ensure that White Space was not being wasted.

He argued that White Space should be licence exempt and said there are a huge range of possible applications for White Space: broadband for rural communities; M2M applications for businesses and so on. 

He concluded: ‘These kinds of applications could be introduced now, so while we are waiting for new spectrum and licenses we could trial new technology, applications and services and see what works.’

Jeppe Jepsen, director of international business relations, Motorola Solutions and member of the board, TETRA + Critical Communications Association made a very strong plea for some 700MHz spectrum to be reserved for emergency and business critical services, such as the emergency services, transportation, utilities, power, oil and gas.

At present these organisations have no access to broadband services other than via the commercial telcos’ 3G and later 4G networks. However, the commercial telcos are not set up to provide broadband services in the way these organisations need to use them. 

They are simply not robust, resilient or secure enough and cannot provide the kind of features required by the police, for example, such as priority call access, group calls and direct mode communications that the UK’s Airwave TETRA two-way radio service provides.

Jepsen argued that ‘spectrum saves lives’ – but there are two different business cases to meet two different needs. A mobile phone or tablet user wants certain services from their network provider, but they also want the fire brigade to be able to communicate so they can get to their house if it is on fire – the consumer, therefore, wants both, argued Jepsen. But if the UK’s mission critical organisations and businesses do not have access to an adequate amount of spectrum the services they provide will be limited.

Why commercial networks do not meet ‘mission critical’ requirements

Jepsen cited the royal wedding of Prince William and Kate Middleton. When the royal carriage passed through London’s Trafalgar Square, thousands of people all took photographs on their phones and uploaded them or sent them – the mobile networks could not cope with the data traffic and crashed in that area – all the security applications using the commercial networks therefore failed to work. The lessons being that a) the emergency services cannot rely on commercial mobile networks for mission critical purposes; and b) you never know where you might hit capacity issues – it’s a moving target.

He also pointed out that the police were able to cope with the riots in London in 2011 because they happened to have extra spectrum loaned to them for the period of the Olympics and the Queen’s Diamond Jubilee. What that meant was that when 16,000 extra police were drafted into London at very short notice to deal with the rioting, their radios all worked as there was enough capacity on the Airwave TETRA network to cope. But that spectrum has been handed back. What happens now, asked Jepsen, if something similar happens again?

He said there are considerable differences in the resilience, availability and security of commercial mobile networks and dedicated ‘mission critical’ networks. The latter’s needs cannot be met through a normal commercial business case. That means a dedicated solution is needed – and that can only be achieved if more spectrum is found for the mission critical community. There is none available at the moment, so 700MHz spectrum represents the first best chance of finding some.

Next steps

Accommodating all those trying to stake a claim to 700MHz and protecting the current DTT and PMSE users will not be easy, but Ofcom will somehow have to find a way. Ofcom’s next move in the process is to begin a consultation on the use of the 600MHz band. The regulator unveiled its long term road map for meeting the demand for additional mobile services on 16 November 2012 when it published its UHF Strategy Statement and Infrastructure Report update.

See also: Ofcom unveils plans to avoid mobile ‘capacity crunch’.

Written by Wireless magazine
Wireless magazine

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