Smartphone users beware – the days of all-you-can-eat wireless data may be numbered
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.
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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 , 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 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 , 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 , 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: , 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 , 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 , 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. ҹ1000 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 £40 and £120, 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.
