Smartphone users beware - the days of all-you-can-eat wireless
data may be numbered
by Jim Giles
YOUR connection to YouTube might be the first to go, with increasingly
choppy videos that one day just fail to download. In your impatience,
you decide to scout out the latest posts in the Twittersphere, except
that, too, is temporarily down. Your email's stalled, and even a
simple text is now too arduous, as the world's phone networks come
crashing down. In the following months, it's almost impossible to get
a lasting connection - even for a voice call. Welcome to 2013, and the
first mobile meltdown.
Although this is the worst-case scenario, some kind of collapse in the
near future is a real possibility. Cellular networks are already
showing signs of strain: your phone may temporarily cut out in large
crowds or at a sporting event or music gig, and if you live in New
York, San Francisco or London, you may have found it increasingly
difficult to make calls in your home city. And things have the
potential to get a lot worse.
Data-gobbling smartphones are, of course, the source of the problem,
as they overload networks with requests for web pages, email and video
streaming 24/7. If the use of these devices grows as expected,
cellphone networks across the world could grind to a halt by 2013 -
and since many core services depend on wireless communication, the
results could be devastating. The only solution will be an overhaul of
the way mobile communications are delivered.
Think of it as a road traffic problem. Governments in Europe and the
US currently allocate a handful of 5-megahertz chunks of the
electromagnetic spectrum to each operator's network, which the
operator uses at each of its transmitters. The chunks of spectrum
correspond to the lanes of a highway, carrying data either to or from
the transmitter. Many operators are given just two 5 MHz chunks - one
lane either way - though some may have as many as five pairs.
Like any road, these highways can only hold so much traffic. Current
3G technologies can send roughly 1 bit of data - a one or a zero - per
second over each 1 Hz of spectrum that the operator owns. That means a
cell tower using one pair of 5 MHz chunks of spectrum can transmit
just 5 megabytes of data per second - a handful of streamed videos at
most.
Cellphone congestion seemed like a distant prospect a decade ago, when
the 3G network was rolled out. At that time, pretty much the only
smartphone users were business execs on their BlackBerrys, leaving the
3G network massively underused.
Not any more. Wireless modems - the "dongles" that plug into USB
drives - added traffic when they emerged around five years ago. Then,
in 2007, Apple launched the iPhone; it has now sold 50 million of the
devices. Suddenly, lots of new people were on the highway, each taking
up huge amounts of road space. A single streaming video occupies as
much bandwidth as around 100 phone calls, for example. As a result,
the 3G highway is now overcrowded, especially in cities where lots of
people use smartphones, triggering waves of complaints in New York and
San Francisco.
Congestion is likely to be a common problem as enthusiasm for
smartphones continues to rise at an extraordinary rate. More than 1.5
million iPhone 4s, the latest version of the device, were sold in the
first week after its June launch. And phones based on Google's Android
operating system are rapidly gaining popularity. If the growth
continues in this vein, mobile traffic will more than double every
year for the next four years, according to predictions by the
computing company Cisco. Which means that the occasional congestion of
today will become gridlock tomorrow, especially in big crowds in
sporting events like the Olympics (see "Olympic demand").
In the past, cellphone companies used innovative engineering to
increase capacity. By making the jump from 2G to 3G (see "Networks
explained"), for example, engineers were able to squeeze 5 to 10 times
as many bits per second into each hertz of spectrum, says Simon
Saunders of Real Wireless, a consultancy based in Pulborough, West
Sussex, UK. This meant more data could rush down the highway without
hold-ups.
Could a similar technique stave off the wireless crunch? Internet
traffic is often what Saunders describes as "snacky": it comes in
bursts as users click on a page, read, then click again. 3G networks
struggle with this kind of traffic, but their successors - Long Term
Evolution (LTE) and WiMAX - should do better.
These technologies have spent years in development, yet they will only
let operators cram roughly 50 per cent more data into the chunks of
spectrum before hold-ups will start happening again - a mere drop in
the ocean when faced with the rise and rise of the iPhone. If LTE were
the only solution in the pipeline, demand might well trump supply in
only a couple of years (see graph), according to a recent report
commissioned by Research In Motion (RIM), maker of the BlackBerry.
Worse still, any successors to LTE will be unlikely to provide the
improvements in data transfer rates that would be necessary to avoid
the crunch. "LTE is so advanced and complex that it has required the
global output of the entire industry to produce," says Peter
Rysavy, a wireless industry consultant based in Hood River, Oregon,
who produced RIM's report. "If there was an alternative that worked a
lot better they would have found it."
Many cellular operators are optimistic about option number two:
widening the road. "If the number of cars on a highway quadrupled
without additional lanes then everything would slow down," says
Christopher Guttman-McCabe, a vice-president at CTIA - The
Wireless Association in Washington DC. "We need more lanes." That
would mean dishing out a few more pairs of 5 MHz chunks of spectrum to
mobile operators to use on their transmitters.
Before this can happen, governments will have to go through the messy
political business of persuading existing owners to part with
underused chunks. That is because much of the spectrum in the 400 MHz
and 3 gigahertz range that wireless operators use is already spoken
for by the military, TV broadcasters and satellite communication. But
now is a good time to be bargaining for bandwidth, as the switch from
analogue to digital television is freeing up space. The US and UK
militaries, which use large swathes of spectrum, will also have slices
prised away from them. In the US, the Federal Communications
Commission says that these factors, together with reallocations from
other owners, will free 500 MHz for cellphones. The UK's
communications regulator, Ofcom, has plans to reallocate close to 300
MHz that could be parcelled off to the various networks.
Unfortunately, there may be a wait: William Webb, head of R&D at
Ofcom, says the UK's auction may take place next year, but progress is
bogged down by arguments between industry and government about who
should be able to bid for the additional spectrum. And in the US, it
may take 10 years to move all of the 500 MHz over to cellular
networks.
Even once that extra spectrum does become available, it will soon be
eaten up by smartphone users and their data-hungry apps. "Freeing up
spectrum would be helpful," says Stirling Essex of CRFS, a UK
company based in Cambridge that sells spectrum-monitoring and
management tools. "But even if you double the amount available you'll
have a problem in a few years. The demand is insatiable."
Even if you double the available spectrum, you'll have trouble in a
few years. The demand is insatiable
Clearly these two routes are not going to allow us to stave off the
wireless crunch for long. Might the only solution be to tax the road
hogs who are bogging down the networks? iPhone owners are used to
paying a flat fee for unlimited internet access through their 3G
connection, but charging them for the amount they download would
surely rein in their usage. "Economists will tell you that when you
make something free people will use a lot of it," says David
Cleevely, chairman of Cambridge Wireless in the UK. "We'll see capping
on data plans. The operators have to get the genie back in the
bottle."
Might the only solution be to tax the road hogs who are bogging down
the networks?
AT&T, which provides internet access to iPhone users in the US, has
already implicitly admitted as much. This June, the company announced
new price plans for the iPhone that come with monthly caps - 200
megabytes and 2 gigabytes for $15 and $25, respectively. The move
hasn't troubled the majority of iPhone owners, since they can save
money by switching from their original $30 unlimited data plan and, in
most cases, will not be bothered by the 2 GB limit, which is
equivalent to watching more than 100 2-minute videos in a month. Yet
AT&T is quietly letting users know that they cannot expect the days of
unlimited browsing to continue forever. These caps may not be onerous,
but unpalatable ones could follow unless other ways of dealing with
demand are found.
Fortunately, there may be a fourth way that would still leave the door
open for cheap and extensive internet use: install a cellphone
transmitter in every home and office. These transmitters, dubbed
femtocells, look like wireless routers and would plug into
broadband connections. By shifting the traffic onto the internet, they
would bypass larger conventional cellphone transmitters, which would
still serve users when they're out.
Femtocells wouldn't be too much of a burden on the home's broadband
connection, since the constraints of cell towers have forced engineers
to create smartphones that use data far more efficiently than
traditional desktops and laptops. Saunders estimates that the
technology could boost capacity by a factor of tens or even hundreds.
As an added bonus, it would also make mobile communication more energy
efficient. Existing cell towers lose 90 per cent of their energy when
the signal passes through an external wall. "Trying to service the
need for better indoor coverage with the outdoor network alone is the
equivalent of trying to improve the experience of reading in bed by
making lamp posts outside brighter instead of installing a bedside
lamp," says Saunders.
Sound too good to be true? There are certainly some questions to be
answered. Health risks are an easy one to deal with. Despite fears
over cell towers, there is no evidence to suggest that radiation from
the towers is dangerous. Home transmitters will run at a much lower
power, as will the phones that connect to them. So there is no reason
to think that femtocells pose a health hazard.
A bigger question is whether femtocells will interfere with each other
when packed into urban neighbourhoods. Interference is a problem for
all transmitters, and engineers routinely monitor transmissions in
areas where signals overlap and tweak the output of towers
accordingly. As transmitters have got smaller and too numerous to
adjust manually, engineers have developed technology that listens to
signals from other sources and makes the necessary changes
automatically. So far, these systems have coped. But femtocells will
add another layer of complexity, and no one knows whether the
automated systems are up to the job.
We will soon find out, however, as the first commercial femtocells
arrived in the past year. Vodafone's Sure Signal system, which
launched in July 2009 and is essentially a tiny 3G cell tower, is
priced at between UKP40 and UKP120, depending on the contract that the
phone owner has with Vodafone. This March, AT&T rolled out a similar
system for $150. That pricing will probably only attract people who
live in areas of bad reception, but demand will rise as prices fall.
One operator - Japan's Softbank - has already started giving
femtocells to subscribers free of charge.
It will be a rocky road ahead as the operators roll out these possible
solutions and jump the inevitable technical hurdles, so we'll have to
keep our fingers crossed that all is in place before the crunch hits.
But there's no doubting the effort will be worth the struggle: now
that we've tasted the wonders of ubiquitous internet, could we ever
live without it?
Olympic demand
Cellphone reception is often patchy at big concerts and sporting
events, where crowds can number 100,000. But that's nothing compared
to the challenge facing the organisers of the 2012 London Olympic
Games. The number of athletes, media and volunteers alone will top
100,000, and that's before you factor in spectators.
It won't just be phones that they will be using. Journalists will come
with wireless microphones and cameras. The emergency services will all
need clear chunks of spectrum in the event of trouble. All in all,
it's a headache for organisers.
To head off problems, Ofcom, the UK's ommunications regulator, has
already published its plans for managing the spectrum. The organising
committee for the London Olympics is building dedicated radio
networks, which will take care of the first responders. Spectrum
cleared by the switch-over from analogue to digital television will be
used for wireless microphones, while the Ministry of Defence and the
Civil Aviation Authority will lend the organisers the spectrum needed
by wireless TV cameras.
The best laid plans can, of course, be derailed by human error. Ofcom
says that equipment operating at the wrong frequency will be the most
likely cause of problems, so it may build a network of sensors to
pinpoint offending sources.
Networks explained
2G was the first digital network and the technology that sparked
widespread use of cellphones. In Europe, the 5 MHz chunks allocated to
individual operators are divided into 200 kHz slices of spectrum, each
of which handles up to eight calls. Although mainly used for voice
calls, it can also transmit data, albeit slowly.
On European 3G networks, multiple calls, internet data and other
traffic are spread across all of an operator's 5 MHz. By devoting a
greater range of frequencies to each user, their data is transferred
more quickly - meaning each user's connection should be faster.
Congestion can occur, however, if too many people want to use the
service at any one time.
The latest networks, WiMAX and LTE, are in some sense a throwback to
2G, since in both cases each operator's 5 MHz allocation is again
divided into discrete 200 kHz slices. Unlike 2G, however, data from
one conversation or call can be placed in different 200 kHz slices.
This on-the-fly allocation helps operators to handle the stop-start
signals characteristic of internet traffic and make the most of the
available spectrum.
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