WITH 4G wireless networks promising a future filled with ultrafast mobile web surfing, you could be forgiven for daydreaming about lolling on the beach streaming HD video on your smartphone. If you live in the US at least, you can keep dreaming.
"A friend got one of the first 4G smartphones in New York a few months ago and exclaimed how wonderful it was," says Robert Atkinson of the Columbia Institute for Tele-Information at Columbia University in New York. Now, Atkinson says, "he has already noticed slowdowns".
It may be the first sign of an impending wireless bottleneck. Wireless spectrum is a limited resource that must be shared, Atkinson says, so the more users there are, the less bandwidth each gets. And usage is soaring. Last month, the Pew Research Center in Washington DC reported that 35 per cent of cellphone owners in the US have smartphones. Many use them heavily: a quarter of owners say the majority of their internet use is via smartphone. Millions of wireless-dependent tablet computers flooding the market aren't helping either.
Last year, the US Federal Communications Commission announced its intention to double available mobile wireless bandwidth by opening up 500 megahertz of new spectrum by 2020, as part of its National Broadband Plan. But 300 megahertz of that is due to come out of the broadcast television spectrum, and TV networks are fighting the move. What's more, some 4G bands freed up from old satellite services are bumping up against frequencies used for GPS receivers and causing interference.
Major US carriers are rolling out a 4G service called LTE (Long Term Evolution) that will achieve speeds of 5 to 12 megabits per second, compared with the 0.5 to 1.5 megabits managed by today's 3G. But in practice those figures will fall quickly: each cell in a 300-megahertz network can transmit only 50 megabits per second in each direction, and in a busy cell this must be shared among thousands of users.
Such an advance is nothing to scoff at, though. "Ten megabits of mobile [wireless] is pretty darn amazing, and should be regarded as fabulously successful," Atkinson says. Still, iPad users already stream video on the go, and the thirst for ever more bandwidth for ever better images seems insatiable.
The crunch is already being passed on to customers. Mobile carriers, expecting to pay premium prices for extra spectrum, are getting rid of their unlimited data deals. In July, Verizon Wireless capped data downloads under its $30 per month plan to 2 gigabytes per month - enough to send 1000 emails or watch just 2 hours of HD video. Each extra gigabyte will cost $10. At that price, if you want to catch a movie, it might be cheaper to head to the multiplex.