Wireless but not cluelessWiFi and other wireless technologies are already part of our lives, and soon they will be almost everywhere. We should try to understand them.
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It's a common sight these days. Men and women sitting on their own in coffee shops and airport lounges, with only their laptop computers for company. Are they lonely? Probably not. They are likely to be in close contact with the outside world because their laptops are connected to the internet. Not by wires but by radio waves – what is known as WiFi. What is WiFi, and where is it used? The world of modern telecommunication technology is awash with acronyms, long numbers and other weird bits of code that few people understand. The term WiFi should be relatively easy because it’s a play on the words 'high-fidelity' or 'hi-fi', which means sound reproduction that is very similar to the original. But 'WiFi' doesn't really stand for wireless fidelity. It’s simply a catchy term for equipment using a particular wireless communication standard, or protocol, known as IEEE 802.11 (more about this bit of code later). Using this standard, computers and other devices can link in a wireless local area network (WLAN), which is a number of computers or computer-like devices that can talk to each other using high-frequency radio waves instead of connecting cables. The WLAN can in turn be hooked into the internet, usually with the aid of a cable. Basically, then, WiFi is a generic name for the main method by which a WLAN is set up. But the term WiFi, as well as the technology itself, has evolved quite a bit since it was first coined in about 2000 and is now used more broadly, particularly by the general public, to mean a wide range of wireless communication technologies. WiFi uses Perhaps the most visible manifestation of WiFi is the coffee-shop laptop tuned cordlessly into a WLAN and hence into the worldwide web, but some phone users might also be doing it by WiFi. VoIP ('voice over the internet protocol') phones enable users to speak to others via the internet. The increasing availability of WiFi means that people with VoIP phones can use them more and more like mobile phones, talking with friends and colleagues over the internet from the same coffee-shop in which they connect their laptops to the worldwide web. WiFi is used in many other applications as well. Some televisions are going WiFi, allowing viewers to wander about their houses with their own portable screens. One company recently offered a camera that connects to the internet via WiFi, allowing people to email photos to friends and colleagues directly from their cameras. A more mundane but widespread use of WiFi is in communication between computers and peripheral devices such as printers and projectors. The great advantage of WiFi over wired networks is that its medium of transmission – air – is everywhere. Potentially, WiFi and other wireless technologies could be made available everywhere to everyone, not only helping a business person on the move but also remote communities that might otherwise wait years for cables to reach them. How does it work?
WiFi equipment works by radio waves, which have a very wide and increasingly sought-after range of frequencies. If the world of communication technology is awash with acronyms, the radio wave spectrum is increasingly jammed with signals as different kinds of devices try to communicate with each other. Extremely low frequencies of 3–30 hertz (or cycles per second) are used for radio communications with submarines; the wavelengths can be thousands of kilometres in length. In contrast, WiFi equipment uses radio waves in the frequency ranges 2.4–2.5 and 4.9–5.8 gigahertz (GHz), with wavelengths of 60 and 120 millimetres. The ranges are classified by the International Telecommunication Union as 'super high frequency' and is much higher than the frequency used for AM radio (300–3000 kilohertz), short-wave radio (3–30 megahertz – MHz), and FM radio and television broadcasting (both 30–300 MHz). It is also generally a little higher than the frequency used for mobile phones and two-way radios (300 MHz to 3 GHz). Telstra's new Next G system, which allows high-speed wireless internet connections, operates at 850 MHz. Other devices that use radio waves in the super high frequency range include microwaves, automatic roller-doors and cordless phones. Bluetooth, a form of wireless technology normally used for very short-range communication between devices such as a laptop and a personal digital assistant (PDA), operates at about 2.4 GHz. At the epicentre of a common WiFi set-up involving personal or laptop computers is a wireless access point, connected by hardwire to the internet. A router converts digital information in the form of 1s and 0s into radio waves, and transmits these via an antenna. It can also receive radio waves and convert these to digital data, which it can then send to the internet via its hardwire connection. Laptop computers or other devices within range using the same WiFi protocol can communicate with the access point and, through it, connect to the internet. The protocol is important. If the laptop and router are to communicate, it is important that they speak the same language. Compatibility between electronic devices is one of the industry's great challenges, and it has been achieved in the current generation of WiFi devices through the adoption of a standard developed by the Institute of Electrical and Electronics Engineers (IEEE) to define the way WiFi equipment operates. This standard, IEEE 802.11, provides the basic parameters within which a WiFi device will operate; for example, it gives the operating frequency and the rate of data transfer. Each area in which WiFi is available is called a 'hotspot' (Box 1: Hotspots and meshes). Where is WiFi heading? WiFi has become very popular very quickly, to the point that in certain sectors of the economy it is almost a prerequisite for doing business. Some hotels would probably lose custom if they didn't offer WiFi to their guests, who expect to be able to log on before they nod off. WiFi-less coffee shops might be bypassed by laptop-toting latte drinkers wanting to connect while they caffeinate. The number of uses to which WiFi could be put is almost limitless. In the home, electrical equipment such as the refrigerator, television, lighting system, microwave and stereo equipment could all be linked and regulated by WiFi. The technology also has exciting possibilities in environmental science (Box 2: Remote sensors and their applications). But perhaps the single greatest advantage of wireless networks over wired technologies is that they are more flexible about the infrastructure required to set them up. That's why community groups have latched onto them, and it is also why they are being pursued in developing countries, where they can be used to bypass the very expensive business of laying cables. WiFi technology is not without problems, security being one of the biggest (Box 3: Security and encryption). But few people think it is a passing fad. So where is WiFi heading? Predicting the evolution of information technology is not easy, especially given its current extraordinary rate of change: this month's boom product might be next month's landfill. But a few things about WiFi seem certain: speeds will increase (Box 4: Increasing speed), the range of uses to which it is put will broaden and its availability will continue to spread. It will also face more competition (Box 5: Competition). Keeping tuned The array of wireless technology already in use can be confusing. Consumers have a huge range of choices but often insufficient information on which to base their purchasing decisions. Can your laptop do WiFi and WiMAX, and does it need to? What does the shop assistant mean when she asks if you want a PDA with bluetooth? Do you need a WiFi rice-cooker? The proliferation of the technology does have one advantage: if you don't understand it and want to find out what it all means, you can at least research it – from almost anywhere! Boxes 2. Remote sensors and their applications 5. Competition Related Nova topics: Communicating with light – fibre optics Mobile phones – communications on the go
Box 1: Hotspots and meshesEach area in which WiFi is available is called a 'hotspot' or sometimes a 'node'. The problem for people in public places who want to use their laptops, palmtops or VoIP phones is finding out where these hotspots are, although they are becoming much more common. One 2006 survey found that the availability of WiFi in New York, USA, rose by 15 per cent in a one-year period; in London, UK, it grew by an even more impressive 73 per cent.Some cities – such as London, UK, and Philadelphia, USA – are promoting the proliferation and 'meshing' of hotspots. Meshing, or mesh networking, is a way of joining hotspots together. The data can 'hop' from hotspot to hotspot, always looking for the best route to its destination (the internet, for example). This means that a user can connect to the network from a much greater number of places, or even while moving around. Setting up a city-wide WiFi mesh means a lot of antennae. One company in Paris, France, offers free internet access for life to people who make their rooftops available for the installation of WiFi antennae. The idea of mesh networks is popular among community groups, who see them as a way of wirelessly connecting computer users in local neighbourhoods. In Melbourne, one group has set up a wireless regional area network (WRAN) using what it calls 'cheap, off-the-shelf WiFi hardware' such as computers or PDAs with WiFi adapters. Although this network doesn't yet provide unfettered access to the internet (due at least partly to licensing and compliance concerns), it does allow participants to interact amongst themselves by sharing files, speaking to each other using VoIP phones, and competing or co-operating with each other in computer games. WiFi meshing technology might also have great appeal in developing countries, making the internet available cheaply and quickly, particularly in urban areas.
Box 2: Remote sensors and their applicationsFor a long time, environmental scientists have braved extreme conditions – high altitudes, rough seas, steep terrain, isolation, rain, snow and wild animals – to gather the data they need to understand natural phenomena. They may need less bravery in the future: wireless sensor networks (WSNs) are taking some of the adversity out of their jobs and simultaneously sparking rapid advances in environmental science. The sensors of a WSN are little different to those used for years by environmental scientists. They measure parameters such as temperature, humidity, precipitation, soil moisture, groundwater or stream levels, salinity, carbon dioxide, oxygen and pH, and they might also record sounds or visual images. In the past, the data gathered by these sensors had to be downloaded manually, requiring a scientist, technician or student to visit the site. This was not only time-consuming, costly and sometimes dangerous, it meant that data often were quite old by the time they were collected. Wireless technology is revolutionising the role of environmental sensors by enabling the remote, automatic processing and transmission of environmental data in real time to a scientist sitting in a lab, office or cybercafe. The WSNs comprise arrays of sensors placed in the field. Micro-processors built into the sensors convert the measurements of these parameters to a digital format, process the data and convert them to radio signals. A radio transmitter then sends the data to a base station, possibly via other sensors that act as nodes in the network in a way similar to WiFi meshing, where the data can be uploaded onto the internet or other computer network. If the sensors are also equipped with receivers, scientists can adjust the nature of the data collected, the periodicity of transmissions and other parameters, without needing to continually venture into the field. The cost-effectiveness of WSNs means that the number of monitoring sites can be greatly increased at minimal cost. Deployment of WSNs is beginning in Australia. Scientists at the CSIRO Information and Communication Technologies Centre in Brisbane have developed a hardy, low-cost WSN called Fleck. This small, solar-powered device has a radio range of 500 metres or more, which can be extended to many kilometres when part of a network of similar devices. Various sensors, measuring such things as temperature, humidity, stream levels and other parameters of environmental quality, can be connected to the Fleck and their data collected, processed and transmitted. The range of possible uses to which WSNs such as Fleck can be put is almost as diverse as the environment itself. One important use already envisaged in Australia is detailed monitoring of the water supply. WSNs could be used to track and predict water quality and quantity at different time-scales, from minute to minute and year to year. Others see WSN applications in agriculture: a property-level WSN could provide farmers with timely information on soil moisture, ambient weather, and even livestock condition, reducing the guesswork needed to manage the land efficiently. Ecologists could put WSNs to good use as one of their great challenges is to collect and analyse sufficient data to fully understand the way ecosystems function. These WSNs may be the key to unlocking many of nature's biggest secrets. Related sites
Box 3: Security and encryption Next time you access a WiFi hotspot, be careful: there might be WiFi sniffers about. Using simple tools, sniffers – or WiFi hackers – can detect WiFi networks and eavesdrop on the data being exchanged by WiFi users. They might be able to read your emails – a real invasion of privacy. They might even be able to capture the password you use to access your email account. They can probably also see what websites you visit: maybe that's not a problem but at the very least it's annoying to have someone reading over your shoulder. The security of WiFi systems has always been a concern in the industry and steps are being taken to increase it. Some websites, particularly those that acquire sensitive information like your credit card details, are protected by SSL, which stands for secure sockets layer, or TLS (transport layer security), which are protocols for transmitting private information. They use a cryptographic system involving the use of two keys to encrypt data - a public key known to everyone and a private or secret key known only to the recipient of the message. There are also virtual private networks (VPNs), which are private communications networks often used within a company or by several companies or organisations to communicate confidentially over the internet. Users can take many other precautions to protect against eavesdroppers and other WiFi security threats. The best protection is knowledge: understand the risks you are taking with your data and take steps to minimise them. Related sites
One of the big advantages of using the super high frequency range is that more bandwidth is available to rapidly transfer a large amount of data, an important quality when used for computer-to-computer communication. A 120-minute movie can be transferred over a WLAN connection in twelve minutes, while it would take about one-and-a-half hours over a typical broadband connection. But even faster speeds are possible over networks now in development. Researchers from CSIRO, National ICT Australia and Macquarie University are experimenting with the millimetre-wave radio spectrum at frequencies of more than 55 GHz ('extremely high frequency'), which can transfer information a hundred times faster than a WLAN. Operating in this part of the radio-wave spectrum has its own issues and problems, but uses will almost certainly be found for it in the next few years. One European consortium has already tested the use of millimetre-frequency radios mounted on a helium-filled balloon floating 24,000 metres above earth to provide internet connections to users at ground level. The idea is to provide high-speed internet access in areas where land-based networks are impractical. Related sites
Fibres For all its strengths, WiFi still has to compete with other promising technologies. Optical fibres carry the vast majority of information traffic around the world and new developments may even increase their role. A research team at the University of Sydney has developed what it calls 'photonic chips', which could be used to replace silicon-based electrical connections, with massive increases in speed and energy efficiency. The wires are one hundred times thinner than existing optical fibre, roughly the diameter of the wavelength of visible light. In the future they could be used to link computers, allowing data to be sent at speeds and volumes even greater than is now possible with WiFi technology. This technology will still be constrained by the fact that it involves a physical connection – a cable – but nevertheless it could play a huge part in future connectivity. WiMAX WiMAX is the term used to describe wireless systems that implement a different industry standard, IEEE 802.16. It was designed originally to provide broadband internet access to stationary devices in the 2–11 GHz radio frequency range, but its proponents are also developing it as a way to service mobile devices in a similar way to WiFi. It can cover a wider area than WiFi (up to 50 km), which makes it an attractive option for providing wireless internet access at a reasonably large, metropolitan-area scale. Related sites
Activities
Further readingAustralasian Science January-February 2007, pages 14-15 CSIRO wins important Wifi patent case (by Simon Grose) Reports that a victory in the US courts paves the way for CSIRO to claim royalties from IT giants.
Cosmos 4 August 2006 Music of the spheres (by Peter Domachuk) An article written by a researcher at the Centre of Excellence for Ultrahigh-bandwidth Devices for Optical Systems.
Ecos No. 132, 2006, page 7 Running a smart farm Describes the development of a 'smart farm' which uses a wireless sensor network to manage water and stock.
Network World 2 September 2002 War driving lessons (by Winn Schwartau) Describes how easy it is to identify insecure wireless networks by 'war driving'.
New Scientist 15 March 2008, page 28 Long-range Wi-Fi threat to satellite communications (by Jeff Hecht)
2 February 2008, page 24 Wi-Fi ‘co-op’ could provide internet for all (by Anil Ananthaswamy) Looks at the development of free, secure Wi-Fi coverage.
20 June 2007, pages 26-27 Point-to-point Wi-Fi brings internet to all (by Paul Marks) Looks at the use of Wi-Fi technology in remote communities.
7 June 2007 Wireless power could have cellphone users beaming Reports on research towards wireless recharging of electronic gadgets.
26 May 2007, page 32 Noise keeps spooks out of the loop (by Jason Palmer) Explores noise encryption as a safe way to send messages.
7 October 2006, page 30 Undersea signals that keep the peace (by Barry Fox) A British firm claims it has developed a wireless modem that works under water.
16 May 2006 'Fly-by-wireless' plane takes to the air (by Duncan Graham-Rowe) Describes a plane that will have a wireless network instead of mechanical connections between its engine, navigation systems and onboard computers.
25 March 2006, pages 28-29 Cities race to reap the rewards of wireless net for all (by Paul Marks) Reports on the increasing number of councils that provide city-wide wireless networks.
11 March 2006, pages 26-27 Welcome to the open source cellphone (by Mason Inman) Suggests that 'build your own' mobile phones may spark new phone designs and software.
3 February 2006 Software-defined radio could unify wireless world(by Will Knight) Describes the trial of a gadget that unifies wireless technologies by switching between conflicting frequencies and standards.
21 September 2005 Cellphones-on-planes era poised to begin (by Celeste Biever) Describes the introduction of in-flight mobile phone use in two European airlines.
9 July 2005, pages 38-41 Take it to the limit (by Dana Mackenzie) Summarises how 'turbo' and LDPC codes are used to filter noise from real signal.
10 July 2004, pages 24-27 Radio sans frontières (by Bennett Daviss) Software defined radio allows users to access and integrate different communications schemes.
Scientific American June 4 2008, pages 14-15 Fight in white space (by Larry Greenemeier) Describes a faster wireless internet service which may affect television signals.
July 2007, pages 64-69 Broadband: room service by light (by Mohsen Kavehrad) Looks at the use of optical wireless technology to solve the limitations of current wireless technology.
June 2007, pages 56-61 Breaking network logjams (by Michelle Effros, Ralf Koetter and Muriel Médard) Examines an approach to enhance the reliability and efficiency of communication networks.
November 2006, pages 46-53 Malware mobile (by Mikko Hypponen) Looks at malicious software such as worms, Trogan horses, viruses and spyware that are aimed at smartphones that allow users to install software applications from sources other than the network provider.
18 September 2006 The new age of wireless (by Andrew Lippman) Suggests that technologies that turn broadcasting 'bugs' into features that open radio spectrum to novel uses will be a boon for consumers.
September 2006, page 22 The net's real security problem (by Tom Leighton) Argues that the greatest threats to online security are the weaknesses in network protocols.
20 February 2006 Cognitive radio (by Steven Ashley) Describes how smart radios and other wireless devices will avoid transmission bottlenecks by switching to nearby frequencies that they sense are clear.
October 2005, pages 68-75 Smart Wi-Fi (by Alex Hills) Looks at how WiFi works and the solutions to problems that arose with WiFi use.
Useful sitesHowStuffWorks, USA
Application areas (Australian Communications Research Network)
Summarises the current areas of communications research in Australia. Includes optical networks, internet access technology, as well as mobile, rural, satellite, wireless data, and broadband communications.
CSIRO, Australia
Australian Bureau of Statistics
The code war (Beyond Discovery, National Academy of Sciences, USA)
Includes a timeline of cryptography, how it works, the Enigma machine and quantum cryptography.
Our wireless future (Scholastic, USA)
A virtual tour of a high-tech home of the future where computers, appliances, and communication devices are all linked on the same
wireless network.
Extinct technologies (Oracle ThinkQuest, USA)
Looks at future communication, television, video, DVD, audio and other technologies.
Australian Radiation Protection and Nuclear Safety Agency
Glossarybinary code. A digital coding system that uses a sequence of only two types of symbols (eg, 0 and 1) to represent data. The two symbols are called bits (an abbreviation for binary digits). For more information see How bits and bytes work (How Stuff Works, USA). broadband. A type of data transmission in which a single wire can carry several channels of data at once. Broadband transmission provides a high rate of data transfer, defined as more than 200 kilobits per second. cryptographic. For more information see Cryptography (Webopedia, USA) frequency. A measure of how frequently a wave goes up and down (oscillates) or the number of waves passing by in a second. A hertz is a unit of frequency – 1 oscillation per second; a kilohertz (kHz) is 1000 hertz – 1000 oscillations per second; a megahertz is 1 million hertz – 1 million oscillations per second. For more information see Sound properties and their perception – pitch and frequency (The Physics Classroom, USA). optical fibre. A glass thread that acts as a guide for lightwaves. Fibres used in telecommunications usually have a cladding of glass of a lower refractive index. In a communication system, several fibres are made up into a cable. radio waves. Low frequency electromagnetic radiation. Radio waves have wavelengths ranging from less than a centimetre to as long as 100 kilometres. The hertz (Hz) is the unit of frequency and means one complete oscillation per second. Many frequencies are much higher than this so other units are used (eg, 1 megahertz (1MHz) = 1,000,000Hz). We divide the radio wave part of the electromagnetic spectrum into bands that are allocated to different uses. These include AM radio (amplitude modulation), FM radio (frequency modulation) and CB radio (citizens' band), television, aircraft communications, satellites, mobile phones and pagers. Within each band, no two transmissions can use the same part of the spectrum – or frequency – at the same time. For this reason, each band within the radio wave spectrum, itself a part of the broader electromagnetic spectrum, must be managed carefully to ensure the best use of this limited resource. For more information see How the radio spectrum works (How Stuff Works, USA). router. A device located where two or more networks connect that determines the best path for forwarding the data packets. telecommunications. The communication of information over a distance by means of radio waves, optical signals or along a transmission line.
External sites are not endorsed by the Australian Academy of Science. Posted January 2007. The Australian Foundation for Science is also a supporter of Nova. This topic is sponsored by the Australian Research Council Communications Research Network.
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