VideoThe newer technology remedies these faults. Each node can relay traffic to other devices, creating an interlocking web. It needs less power because the data travel only a small distance to another node. It is self-organising and self-healing. If one node goes down, the system finds an alternative path for the traffic. And the more devices are attached, the more efficient and resilient the network becomes.
Factory controls like those at BP are obviously useful, but they do not add up to a volume business. A good example of a large-scale application is building management. Thanks to wireless communications, lighting, heating and air-conditioning can be controlled centrally to keep energy bills down. So when a guest checks out of a hotel the receptionist can adjust the air-conditioning to stop it needlessly chilling the furniture. This could also be done through a wired system, but wireless technology offers lower installation costs and greater flexibility.
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Some firms are installing such systems in older buildings as well as integrating them into new ones. Riga Development, a wireless-technology firm in Toronto, has worked with hotels in Canada and the United States to replace ageing analogue thermostats with digital ones that are around 35 percent more energy-efficient. It wirelessly links the new temperature-control panels with heating and air-conditioning units, at a cost of around $350 per room. Each room can also be controlled from the front desk. And thanks to the wireless mesh network, the panel in each room also acts as a relay for the data traffic from other rooms back to a central control point.
At a medium-sized office park in Las Vegas, wireless temperature controls were installed in a few buildings containing around 200 offices, says the media-shy maintenance manager (who did not want his or the company's name to be used). Temperatures in the Nevada desert tend to extremes and landlords are responsible for energy bills, so managing a building's climate makes a difference to the bottom line. The new wireless thermostats allow rooms to be controlled centrally on a PC or over the web. The adjustments that tenants themselves are able to make can be controlled too, so that heating or air-conditioning is not used to excess. The system was cheap to put in, mainly because it required very little installation, the manager explains. Tenants are happier and the savings on the energy bills have been considerable, he says; "conservatively 25 percent".
These uses of wireless are just the beginning. Sensors are not only being added to devices that already have electronics on them, but being put on to things that were formerly bare of any technology at all. For example, they are being fitted to buildings, bridges and roads to monitor their structural integrity. The sensors can identify stress and early cracks that need attention. Sensors are also being used to monitor the environment. Scientists now use them to measure the climate in areas that would have been impractically small when sensors were more costly — say under individual plants rather than in a thicket.
Wireless sensors are also cropping up on farms, to measure temperature, moisture and light on tracts of land where wired sensors cannot easily go. Among the first big users are vintners, because their crop is particularly valuable and even small variations in climate can ruin it. Ranch Systems, for instance, supplies equipment and software to a dozen vineyards in Northern California. A fleet of sensors allows growers to monitor wind, water and soil and air temperature. This helps them set the watering schedule to suit the different needs of each part of the vineyard and manage frost, disease and pests, explains Jacob Christfort, the founder. "It is a little like da Vinci and the helicopter," he says, referring to the artist's famous sketches that presaged later inventions. "These things were conceptually possible all along, but some mundane advances are required before it all comes together and somebody actually does it."
The technology has become so accessible that it is sparking a cottage industry of small entrepreneurial firms. Moteiv is putting sensors on firemen's uniforms to relay information about the fire and let their colleagues know exactly where they are. The system can even provide the firemen with information such as floor plans, projected onto their masks. Other applications now on sale include wireless home-security systems and wireless beacons for sailors to tell the crew when someone has fallen overboard. Yet the very diversity of its uses highlights one of the barriers to the development of the technology: they all have to be put together in a bespoke fashion. Wireless technology is so new that it has yet to be simplified and standardised, as most technologies are over time, notes Monica Paolini of Senza Fili Consulting.
Another complication is that nobody really knows how much stress a collection of wireless sensors will put on a network, other than that it will probably be different from what happens on the internet. Much internet traffic is asymmetric, with computers at the edge of the network receiving hundreds or thousands of times more traffic than they send. A single mouse-click to request a file brings a massive YouTube video in return. With sensor networks this traffic asymmetry is inverted: they send far more data than they receive. Although each individual consignment of data is tiny, they add up. And some sensors send out a steady heartbeat, if only to say "I'm still here!", which sets off a communications session throughout the network.
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