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Will we ever... face a wireless spectrum crunch'?

2013-10-15 09:26:46

By Frank Swain

Our hunger for wireless data is threatening to crash our communication networks

- but there are ways to avoid disaster.

If you think city streets are congested and badly planned, consider the air

surrounding them. It is infused with data, pouring forth from phone masts,

radio towers, wi-fi routers, bluetooth, taxi radios, airport beacons, even

remote control garage doors. Our lives have become so saturated with data the

fear is that communication networks could grind to a standstill entirely - it s

known as the spectrum crunch. Yet could we find ways to avoid this looming

data-geddon?

The problem is that so many wireless devices nowadays use the radio spectrum to

transmit and receive data. When this spectrum was first divided up between

different users, the authorities treated it like empty land. Swathes were

allocated for different uses, including radio, television, navigation,

astronomy, maritime services, aeronautics, military and of course,

telecommunications. However, some of these industries grew much faster than

others. For instance, while much of the military spectrum remains unused, the

part reserved for telecommunications is bursting at the seams. For instance,

while much of the military spectrum remains unused, the part reserved for

telecommunications is bursting at the seams.

The situation for telecoms became so dire that in 2012, London faced the very

real threat that its wireless communications network would fail under heavy

load. During the 2012 Olympic Games, British communications regulator Ofcom had

to borrow part of the military spectrum to ensure the audio, visual and sensor

feeds didn t grind to a halt as the athletes were sprinting across the finish

line.

Our demand for data is poised to rise in the coming years, so Ofcom and many

other communications regulators worldwide are concerned. There's a significant

risk of a spectrum crunch by 2020, says Simon Saunders, director of technology

at Real Wireless, an independent consultancy based in Pulborough, UK. If the

problem is not addressed, in local areas with intense demand there is a risk

everything will slow down.

Many governments, then, are looking for ways to alleviate the problem before

the wireless signal to our electronic devices starts failing. So far, the

principle strategy has been to find more spectrum. That s not easy. As a finite

resource, we can no more create extra spectrum than we can create extra land.

Instead, spectrum allocated to one party can be reassigned to another, but this

process involves evicting the current tenant, and that isn t something to be

taken lightly. Many countries were given much-needed breathing room by the

switchover to digital television, which freed up the 800MHz band previously

allocated to analogue TV. But this shift required all televisions to be

augmented or replaced.

The body responsible for regulating the radio spectrum, the International

Telecommunication Union, will meet in 2015 to discuss the problem at the World

Radio Conference in Geneva in 2015. There, it s likely that the assembled

parties will flag additional parts of the spectrum they want to see freed up

for telecommunications. Some countries are already forging ahead. In the UK,

for instance, Ofcom is eyeing up some of the under-used military spectrum to

sell off, with the proceeds going to the Ministry of Defence. And in 2012, the

US Federal Communications Commission approved a plan to encourage broadcasters

to sell under-used parts of their allocated spectrum to other users. The first

of those auctions is to be held in January next year, when the 10MHz H band

is expected to go for at least $1.56bn.

However, there are only so many land grabs and sales available. Additional

spectrum may double capacity in the next ten years, warns Saunders, but it

will not be enough to feed demand.

In a report published this month, Ofcom warned that data demand in the UK could

increase 80-fold over the next two decades, driven primarily by the increase in

mobile broadband.

What other options are on the table? Already, mobile service providers practice

intensive and complex traffic management to ensure you get a steady signal.

This includes throttling data allowances in real time, but this strategy only

works when low impact use such as voice calls can be prioritised over

high-resource uses such as streaming video. Throttling preserves a strong

connection to a cell tower and avoids dropped calls or blackspots, but at the

cost of reducing bandwidth available to each person. This might not be an

acceptable compromise if you expect and pay for a reliable, high speed data

connection.

Arguably the most important strategy in avoiding a spectrum crunch is resource

sharing. Spectrum-sensing devices that can automatically detect congestion and

switch to a less polluted radio band hold a lot of promise, but this technology

is still some way in the future.

A temporary fix to reduce local congestion is to increase the number of mobile

towers and thus reduce the size of cells. This allows operators to serve more

users without needing any additional spectrum space, much the same way as

opening more checkouts in a busy supermarket. But more towers means more

infrastructure to build and maintain, and less revenue per tower. And as more

and more data-hungry devices are added to the grid, the number of towers needed

grows. It will become harder and harder to build more cells to accommodate

traffic, says Saunders.

Another way to shrink the electromagnetic footprint of our digital

communications is to piggyback one service on top of another. From the customer

s point of view, streaming video content to a digital television is no

different than streaming it to a mobile phone, so it makes little sense that

these two services should be forced to operate in different bands. For example,

Microsoft has provided broadband to people in rural areas of Africa by using

the white spaces of the TV spectrum essentially, the unused frequencies.

This type of doubling up also offers the best chance for a cost-effective

development of the much vaunted Internet of Things. So far, no one knows who is

going to pay for the infrastructure to connect billions of devices, each of

which offers the mobile operator a tiny fraction of the revenue that a

smartphone customer would generate. Allowing the Internet of Things to run on

the back of another service, rather than in a dedicated spectrum space of its

own, might be the only way to finance it.

This kind of spectrum sharing comes with its own problems. US company

LightSquared came to blows with the satnav industry over its attempts to roll

out 40,000 transmitters to provide blanket wireless broadband coverage to its

customers. The powerful transmitters threatened to drown out the weak GPS

signals which operated in the adjacent band. Eventually, the FCC ruled that

LightSquared could not operate in that part of the spectrum, and the company

filed for bankruptcy. (It has since relaunched, intending to move to a

different part of the spectrum with more accommodating neighbours).

As our apparently insatiable demand for data continues to grow faster than the

space allocated for it, we should expect to see more friction between these

neighbouring spectrum bands. The more densely you pack users, the more

problems you'll have with noisy neighbours, says Saunders. 4G has barely

started to roll out in the UK, but it s already known that it will inflict some

interference on digital TV. So far the effect seems to be small, but it s

further evidence that the harmony between different spectrum users rests on

strong regulation.

For the spectrum crunch to be avoided, careful management of our

electromagnetic space will be required, just as pressures on land fostered an

intricate web of laws and regulations that continues to shape our cities today.

This is possible, and widespread outages can be avoided, but governments cannot

rest idle. There is enough spectrum for everyone, says Saunders. So long as

it is in the right hands, in the right place, at the right time.