THE tangled web of wires beneath computer desks could soon be a thing of the past. The same goes for the jumble of cables that feeds audio equipment and TV sets. The boxes of electronics around the home and office will still need to be plugged into power sockets. But the means for delivering signals to and from them are about to go wireless in a big way. And not just any old wireless: the new-fangled radio connections operate in the unlicensed 60-gigahertz band, where bandwidth is abundant and capable of providing data rates that rival those of fibre-optics.
It is not just an obsession with neatness and convenience that is causing cables to give way to radio waves. When it comes to shoveling truly humungous quantities of data from one device to another, hard-wired connections, surprisingly, can run out of capacity long before airwaves.
The switch is being driven by the sheer size of today’s high-resolution multimedia files, as users seek to upload them from smartphones, tablets and laptops to television screens, computer monitors and docking stations. Given the trend to ever richer media, equipment makers have decided cables can no longer cope.
Though introduced a mere decade ago, the HDMI (high-definition multimedia interface) cable used for feeding pictures and sound from cable boxes, digital recorders, video-game consoles and Blu-ray players to television sets and computer monitors looks like being the first to go. The long-serving RCA cables that festoon the backs of audio components will no doubt vanish in the process.
Already Wi-Fi connections working at frequencies in the 2.4-gigahertz or 5-gigahertz bands have begun to replace USB (universal serial bus) cables for connecting computers to printers, keyboards and mice where data rates are modest. But the new 60-gigahertz connections look like being more than a match for even the “SuperSpeed” version of USB 3.0.
What about that old network fixture, the Ethernet cable? Though typically used for transferring files around local-area networks at a humble one gigabit a second, Ethernet has the potential to go 100 times faster than that. As such, it is probably safe from 60-gigahertz streaming for the time being. Though once 60-gigahertz radio chips start being incorporated in smartphones, tablets and laptops, hard-wired connections of all sorts will be threatened with extinction.
The 60-gigahertz band resides in the EHF (extremely high frequency) part of the spectrum, which spans frequencies from 30 gigahertz to 300 gigahertz. Beyond these reside the far infra-red and visible-light regions of the electromagnetic spectrum.
With bandwidth normally considered a precious commodity, how come the 60-gigahertz band—from 57 gigahertz to 64 gigahertz in North America (59-66 gigahertz in Europe and Japan)—has gone largely unexploited? If truth be told, they were left free for unlicensed public use largely because governments considered them worthless.
There is good reason why they did. Oxygen molecules in the atmosphere resonate at 60 gigahertz, absorbing energy from radio waves at this frequency and attenuating them severely. Rain also causes such signals to fade. Even the normal humidity of the atmosphere takes its toll on the distance these so-called millimetre waves can travel. (At 60 gigahertz, the wavelength is 5mm.) They are also blocked by foliage and walls, and antennas need to be within line-of-sight of one another.
But for some applications, such restrictions can be a definite advantage—as in device-to-device communication over distances of up to ten metres (33 feet) or so. Such radio waves are ideal for beaming high-definition video from a computer to a television set across a living room, or for connecting a tablet to a docking station a few centimetres away.
Portable devices fitted with 60-gigahertz radio chips can swap vast amounts of data almost instantly when brought within range of one another. Their antennas need be only a couple of millimetres in size—making them small enough to be embedded in the radio chip itself.
Over the years a number of wireless connections have emerged with names such as Wireless Home Digital Interface, Wireless USB, WiDi, Airplay and Miracast. Most operate in the unlicensed 5-megahertz band used also by Wi-Fi. As such, they have limited scope for streaming the really heavy volumes of data expected in the future.
Two wireless technologies, though, stand out. One, an industry-led initiative known as WirelessHD, has been around since 2008. The other, a standard backed by the Institute of Electrical and Electronics Engineers (IEEE) known as WiGig, published its specification in 2010. In IEEE terminology, WiGig is known as 802.11ad.
WirelessHD and WiGig do broadly the same thing. In their present incarnations, both are capable of transmitting data at around seven gigabits a second—ten times faster than the slickest form of Wi-Fi networking today—and have peak data rates of around 30 gigabits a second. Future versions of both are expected to raise peak rates much higher. For comparison, transferring uncompressed high-definition video—from, say, a Blu-ray player to an HDTV set—requires a throughput of around 3.5 gigabits a second.
Both technologies address the range problem with a technique known as adaptive beamforming. This uses an algorithm on the transmitter side to determine where the receiver is located. It then focuses the signal between the two devices into a pencil-thin beam.
Apart from allowing even faster data transmission over longer distances, pencil beams provide extremely secure connections. With conventional Wi-Fi, which broadcasts in all directions, eavesdroppers can be outside in the carpark. To intercept a pencil beam they have to be in the same room—in the beam’s actual path—to have any chance of success.
Having started earlier, the WirelessHD group has had products in the marketplace for a year or so. For $399, the DVDO Air can send high-definition video, along with 7.1 channels of sound, from a cable box, Blu-ray player, computer or video-game console to a television receiver on the far side of the room. The Aries Prime from Nyrius does much the same for $299. Meanwhile, the first WiGig application is a Dell laptop that sports a 60-gigahertz chipset as well as Bluetooth and Wi-Fi radios.
Which 60-gigahertz technology will prevail? For consumers, it does not really matter. Suffice it to say that the Wireless Gigabit Alliance (promoter of the WiGig specification) recently merged with the Wi-Fi Alliance, the body responsible for certifying the IEEE’s 802.11 family of wireless standards (“a”, “b”, “g”, “n” and, coming soon, “ac”). In due course, the Wi-Fi Alliance is expected to incorporate WiGig technology in its own “ad” offering. Anticipating such a move, two specialist chipmakers, Marvell and Wilocity, joined forces last year to bring tri-band Wi-Fi devices operating in the 2.4-gigahertz, 5-gigahertz and 60-gigahertz bands to market sometime in 2014.
The promise is that, once the wrinkles have been ironed out, 60 gigahertz Wi-Fi could be an even bigger driver of innovation in the years ahead than the original 2.4-gigahertz Wi-Fi was in its day. If uncluttered spectrum is what developers hunger for, then the unlicensed 60-gigahertz band is the last great frequency domain awaiting to be gobbled up. After all, it is home to a whole seven gigahertz of virgin frequencies. Traditional Wi-Fi had no more than half a gigahertz at its disposal, which it had to share with microwave ovens, cordless phones, garage openers and the like. Yet it still managed to launch one of the biggest revolutions in wireless history. With luck, history could be about to repeat itself.
Via The Economist