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Radio Crossroads

Richard Womersley sets the scene for the upcoming world radio conference, where the agenda for mobile spectrum is likely to dominate proceedings

Radio Crossroads

Over the past three years, hundreds of experienced and knowledgeable radio spectrum experts have met on a regular basis under the auspices of the International Telecommunications Union (ITU) and expended thousands of hours of effort discussing and debating material that will inform attendees at this year's World Radiocommunications Conference (WRC-15). The WRC is the culmination of this effort and takes place for four weeks this November at the ITU headquarters in Geneva, at which attendees from the world's national spectrum regulatory agencies will together expend many more thousands of hours of effort to consider and agree revisions to the ITU Radio Regulations (RR). The RR set out, for the whole planet, which particular radio frequencies should be used for which purposes.

In addition to national regulatory authorities whose views and votes are the only ones that count when deciding on changes, many organisations that use radio spectrum will also attend and try to ensure that any decisions that are taken are to their liking. While many people might feel that spending such a large amount of effort on such a seemingly obscure document may appear to be a waste of time and money, the RR are of crucial importance in determining how wireless services across the world will develop. The situation is not the same for the whole planet, however, as the ITU divides the world into three regions:

  • Region 1 comprises Europe, Africa and the Middle East
  • Region 2 comprises North, Central and South America and the Caribbean

Region 3 comprises Asia and the Pacific. But as radio signals do not stop at international borders, there is need both for coordination between neighbouring countries, and between the neighbouring ITU regions, hence the need for all three regions to meet at the same time. In addition, having the same piece of spectrum harmonised for use by the same service across the globe offers both enormous economies of scale, and reduces the potential for cross-border interference.

Notwithstanding this desire for a harmonised approach, according to Article 4.4 of the RR any country can use any piece of radio spectrum for any type of service that it chooses, but it can only do so as long as it does not cause interference to neighbouring countries and equally, it must accept any interference that is caused by any services in neighbouring countries that are operating in accordance with the RR. So in the majority of cases, unless a country is large and has its major cities sufficiently far from its borders so it is unlikely to affect its neighbours (eg. Australia or New Zealand), use of radio frequencies as defined in the RR is the chief constraint and there are rarely significant derogations from the rules. This is why getting the RR right is such an important task.

 

Agenda for WRC-15

The topics under discussion at this year's WRC were agreed at the previous WRC in 2012, and are defined by a series of agenda items. Some of the topics on the agenda are relatively non-contentious insofar as most countries support similar outcomes. For example, agenda item 1.5 is aiming to get agreement that certain satellite spectrum can also be used for controlling unmanned aircraft systems (UAS), better known as drones; and agenda item 1.11 is seeking more spectrum for earth observation satellites. While it is true to say that no changes in spectrum use are non-contentious, some matters are easier to agree than others if the majority of countries and spectrum users recognise the overall benefits of change.

Three of the agenda items, however, appear to have generated the vast majority of pre-conference activity and are likely to spawn most discussion during the conference itself. In particular:

  • Agenda item 1.1 is seeking to identify more spectrum for mobile broadband services (known at the ITU as International Mobile Telecommunications or IMT)
  • Agenda item 1.2 is seeking to ratify the allocation to IMT of spectrum between 694 and 790 MHz, which used to be allocated to broadcast television services
  • Agenda item 10, which sets the agenda for the next WRC (expected in 2019), will discuss even more spectrum for IMT.

All of these agenda items are concerned with finding additional radio spectrum for (commercial) mobile telecoms networks. As of the last WRC, the amount of spectrum already identified and available at the ITU for IMT services across the three regions is in the first table below. Not content with this, the IMT industry has, over the past few years, pushed for even more spectrum. An ITU working group that considered how much spectrum will be needed for IMT services by the year 2020 has predicted that between 1320 and 1960 MHz will be required (see Report ITU-R M.2290, 'Future spectrum requirements estimate for terrestrial IMT'). The difference between the lower and higher limits are a consideration of low and high traffic density (eg. the amount of data that users will consume and how many users will be contained within a given area).

 

GSMA's focus for spectrum

As WRC-15 approached, the GSMA, the industry body for all IMT operators, has narrowed its focus on spectrum that it sees as being the lower hanging fruit for reallocation for mobile services, and has now homed in on the following bands:

  • 470–694 MHz – this is the remainder of the UHF television broadcasting band, still in heavy use for digital (and analogue) services in many countries
  • 1350–1518 MHz – this spectrum is often governmental and used for fixed links
  • 2700–900 MHz – this is an aeronautical radar band, and while in heavy use in some countries, in many there are no radars in this frequency range
  • 3400–4200 MHz – this is the satellite C-band used for downlinking from over 150 satellites globally, especially in areas of high rainfall where other frequencies do not function effectively.

But those who currently use this spectrum (eg. broadcasters, governments, air traffic controllers and satellite operators) have often already given up substantial amounts of spectrum to the mobile industry and are not keen to relinquish yet more. They argue that the IMT industry (and the ITU) have not categorically proven the need for more spectrum. In particular, the European Satellite Operators Association (ESOA) and the European Broadcasting Union (EBU) have disassembled the ITU's spectrum forecasts and found that the values used in predicting the amount of data traffic far exceed any reasonable forecasts, including those put forward by the mobile industry itself.

The middle table shows population density values (people per square kilometre) contained in the ITU's predictions and values for Japan, Russia and the UK based on alternative recognised sources. Similar large disparities exist between the amount of data that the model assumes each user generates per month, and the predictions by bodies such as the UMTS Forum and Cisco. It can be seen that even the ITU's values for suburban population density far exceed the urban population density.

The EBU, ESOA and others claim that the values provided by the ITU's study group are so high as to be completely unrealistic and may only apply in the most densely populated square kilometre on the planet. They further argue that decisions on spectrum for the whole world should not be taken on such a basis. As an example, they say that the population density value used by the ITU model for urban areas is so high that it equates to putting the entire population of the US into an area the size of Paris. The ITU study group, on the other hand, recognises that its figures are on the high side, but argues that any mobile network should be designed for the 'worst case' in order that it will then be able to provide a service under all conditions. Whether or not the spectrum requirements for downtown Tokyo on a busy holiday afternoon is applicable for downtown Dar es Salaam is an issue that attendees at the WRC will need to consider.

Satellite operators, the military, broadcasters and others are not convinced that the IMT industry has proven that it needs more spectrum. They argue that developments in technology (such as 4G and, by 2020, 5G), together with an increasing amount of offloading of wireless data onto WiFi will mean that the mobile industry will be able to cope with what some have termed the 'data tsunami' for many years to come without access to new spectrum.

But this is not the end of the matter. The same ITU model was used in 2007 to predict both the amount of mobile data that would be generated in the period to 2015 and also the amount of spectrum that would be needed. At that time (2007), the model showed that by 2015 the amount of spectrum that would be needed for IMT services would be 1300 MHz (see Report ITU-R M.2078 'Estimated spectrum bandwidth requirements for the future development of IMT-2000 and IMT-Advanced'). It also estimated annual mobile data demand growth over the same period. By 2015, the amount of spectrum actually being used by mobile operators was far less than the ITU demand figures, yet the amount of data being carried by those networks was far in excess of the ITU forecast.

As an example, for the three ITU regions, the amount of spectrum that has generally been licensed to mobile services is shown in the third table. The amount of spectrum being used by mobile operators in a few representative countries is also shown.

 

Actual licensed spectrum

Notable here is that the amount of spectrum that has been licensed is, in most cases, far below that which the ITU has identified for IMT and even further below the original forecasts. This appears to be down to two reasons:

  • First, the spectrum identified by the ITU is not vacant. It is being used by a series of incumbent services such as broadcasters and government users. As such, it takes a degree of time for regulators to gain agreements to 're-farm' this spectrum and make it available for mobile services. Some regulators are better at this than others. Even when the re-farming process has been agreed, it can take a long time for regulators to move the incumbent users out of their spectrum and then an equally long time to run award processes (eg. auctions) that allows mobile companies to gain access to it.
  • Second, mobile networks are operating far more efficiently than the ITU predicted. Spectrum efficiency is higher and the number of cell sites is also higher, meaning that networks are able to deliver more data capacity in less spectrum. The impact of people offloading traffic onto a WiFi network when they are at home, or in a public hotspot, may also have impacted the actual traffic being carried on mobile networks.

As an example, the 2100 MHz 3G mobile band was identified for IMT services by the ITU at the 2002 WRC. Many countries have managed to re-farm this spectrum and license it to mobile operators, but in Africa, for example, it is estimated that 30% of countries have still not licensed this spectrum. Conversely, consider the case of the 700 MHz band. It was proposed as a mobile band at the last WRC in 2012 and will be ratified as such at the forthcoming WRC, but it is now licensed and will shortly be in service in a handful of countries, having taken less than three years to go from identification to licensing to usage.

 

Weighing up the mobile case

The fact, however, that it has taken over 13 years to get some mobile spectrum from an identification position at the ITU to putting it in use, is exactly the reason that the likes of the GSMA argue that if we are to avoid a future mobile spectrum shortage, decisions over spectrum usage have to be taken now. But if regulators are struggling to convince incumbent spectrum users to clear out of mobile bands that have been identified for ten years or more, it is not going to solve any of their problems if even more bands are identified. The newer bands, having taken longer to identify and study, are more difficult to re-farm than those already identified. Some countries, especially those with a weak regulatory authority, and which already feel mildly embarrassed about their inability to re-farm spectrum for IMT services, will be left with even more egg on their faces as the amount of spectrum they have managed to license is an even smaller percentage of that identified.

To make matters more contentious still, the mobile industry is also developing the next mobile technology, 5G. While it is too early to fully know what 5G might consist of, the industry is trying to carve out a home in the radio spectrum for it. Having recognised that there is little below 6 GHz that has not been studied for possible mobile use, attention is turning to higher frequencies and in particular those above 10 GHz. As with the lower frequency bands being contended at the WRC, these bands are not vacant and are used by many of the same parties that are being put under pressure for mobile spectrum below 6 GHz, ie. government, transport and satellite operators.

These parties argue that if the focus for new spectrum is above 31 GHz (ie. avoiding the spectrum between 10 and 31 GHz), then there is enough relatively free spectrum for 5G and it would not impact their existing operations. There is therefore potential for a compromise here (about as near to a 'win-win' as it gets at the ITU). If 5G proponents are willing to stick to new frequencies above 31 GHz, the majority of the objectors would be (relatively) happy.

So what should the administrations attending WRC do? Should they throw their weight behind the mobile industry and forge ahead with identifying new spectrum for IMT services? Or should they take a more conservative approach and delay any decisions on new mobile spectrum until such time as the IMT industry has unequivocally proven its need, given that incumbent users have needs too?

Much will depend on national circumstances. Countries that rely heavily on the IMT industry for jobs and wealth creation (eg. those with major manufacturing bases such as South Korea, Japan, China and the US) will no doubt be pressing hard for more mobile spectrum. Those that place more emphasis on the use of the spectrum for some of the other services such as broadcasting, satellite and government will take a different stance. As always, the discussions at the WRC will be long, heated and drawn out but the outcome, whatever it may be, will be worth the effort.

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