WI-FI as we know it is reaching the limits of its usefulness. It just can’t keep up with our appetite for services, such as new video formats, that gobble up bandwidth. So what’s next in the world of blisteringly fast home-based wireless technologies?

For clues to where Wi-Fi is going, it helps to delve into the soup of standards that will shape the future of wireless communications.

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To date, most Wi-Fi hotspots use one of three connectivity standards, 802.11a, 802.11b and 802.11g – the current favourite. Wi-Fi devices connect to the internet over the radio waves in bands around the 2.4 gigahertz and 5 GHz frequencies, as defined by the international standards body, the Institute of Electrical and Electronics Engineers (IEEE).

Last year, the IEEE agreed the specification for a new Wi-Fi standard, 802.11n, which operates in both the 2.4 GHz and 5 GHz bands (see table). This standard is theoretically capable of transmitting data at 300 megabits per second – up from 802.11g’s paltry 54 Mbps. The new Wi-Fi standard should make streaming high-definition video a less jerky experience than it has been so far. And further changes may take speeds up to 600 Mbps.

Even so, based on past experience, additional bandwidth will soon get eaten up by data-hungry services, so what are the prospects for even faster wireless transmission?

One method being considered is to transmit data in a different band of frequencies – generally speaking, the higher the frequency, the more data can be shifted. Several consortiums are already building systems which can operate around the 60 GHz band, including the IEEE’s proposed 802.11ad standard.

In mid-2009, the Wireless Gigabit Alliance (WiGig), a consortium of technology companies including Microsoft and Intel, published its specification for 60 GHz wireless communication technology. Ali Sadri, president of WiGig, says that its protocol will support data transmission rates up to 7 Gbps. At that speed, you could download the equivalent of a Blu-ray disc onto your laptop in seconds.

While WiGig’s speed would easily surpass that of Wi-Fi, its range will be far shorter, at around 10 metres in open air. This is because radio waves at 60 GHz are subject to interference in the air, as the bonds in oxygen molecules resonate with the waves. That means it will not penetrate walls, confining your super-fast internet to a single room. Sadri thinks that may actually be an advantage, improving users’ security by preventing outsiders tapping into your network.

The big advantage of 60 GHz is that it is free, says Stan Skafidas, an electrical engineer at Australia’s national technology research group, NICTA. This is because governments considered it unusable, so it doesn’t require a licence, he says. Skafidas has been developing a chip that has all the components needed for 60 GHz connectivity built in.

NICTA’s so-called Gi-Fi chip will comply with the 802.11ad standard when it’s finalised and allow downloads of up to 5 Gbps. Because the chip is built in the same way as most silicon chips, it should be possible to make them cheaply enough to compete with Wi-Fi, says Skafidas. NICTA demonstrated prototype chips last year and expects to go into full-scale production soon.

“Because it’s very cheap, you could envisage a situation where every power point in your house has this chip set into it,” says Skafidas, so the short transmission range of 60 GHz won’t be a problem.

Elsewhere, the IEEE has working groups looking at improvements to Wi-Fi’s capability. Its 802.11ac standard will operate around the 5 GHz band, like 802.11a, but data will be transmitted over a greater range of frequencies around that band to boost data rates. The standard isn’t expected to be finalised until 2012, though it expects to exceed 1 Gbps.

Others think we should abandon the overcrowded airwaves altogether and concentrate on light. Mohsen Kavehrad, an electrical engineer at Pennsylvania State University in University Park and his team have been working on an optical transmission system that is capable of high data-transmission rates. One problem with using light is that you normally need a direct line of sight between transmitter and receiver. Kavehrad’s system gets round this by using a high-power laser diode to generate pulses of infrared light, which can be bounced off the ceiling. The reflected light is captured and refocused at the receiver, where a special semiconductor known as an avalanche photo diode turns light into a digital signal. The team have been able to transmit data at 1 Gbps, and think it can go even faster. They presented the work at the SPIE Phonotics West Conference in San Francisco last month.

Adding reflectors and more sensors could allow light to be bounced into separate rooms, claims Kavehrad, getting round one of the problems with 60 GHz radio systems. Optical systems should also be “greener” as their components generally use less energy than those transmitting radio waves. It would not interfere with other electronic systems, making it suitable for hospitals and aircraft, where Wi-Fi use has traditionally been restricted, he adds.

While Kavehrad’s system is undoubtedly impressive, designing 60 GHz systems will be easier as the equipment is similar to existing Wi-Fi. Also, using radio waves to access the internet is a tried-and-tested technology, says Rod Tucker, an electrical engineer at the University of Melbourne, Australia.

But even this super-fast wireless connectivity will one day be superseded, so all approaches will remain in play. “There is an ever-growing upward demand on bandwidth. We’re not just talking HD video. It’s going to be 3D, then super HD video then super 3D. When in the history of telecommunication has the demand for more data stopped?” says Tucker. “Never.”

via Wireless speed freaks set to leave Wi-Fi standing – tech – 25 February 2010 – New Scientist.

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