Imagine for a moment if all the wireless
connections in the world were instantly replaced by cables. You'd have cables stretching through
the air from every radio in every home hundreds of miles back to the
transmitters. You'd have wires reaching from every cellphone to every phone
mast. Radio-controlled cars would
disappear too, replaced by yet more
cables. You couldn't step out of the door without tripping over cables.
You couldn't fly a plane through the sky without getting tangled up.
If you peered through your window, you'd see nothing at all but a
cats-cradle of wires. That, then, is the brilliance of wireless: it
does away with all those cables, leaving our lives simple, uncluttered, and
free! Not so long ago, the word "wireless" sounded like a dusty old throwback to
the 19th-century experiments of Hertz and Marconi; today, it's a crucial
link to the Internet and the online world we all depend on. Let's take a closer look at how it works!
Photo: A typical wireless router. This one, made by Netgear, can
connect up to four different computers to the Internet at once using wired connections,
because it has four ethernet sockets. But—in theory—it can connect far more machines
using wireless. The white bar sticking out of the back is the wireless antenna.
Wireless started out as a way of sending audio programs through the
Pretty soon we started calling it radio
and, when pictures were
added to the signal, TV was born. The
word "wireless" had become pretty
old-fashioned by the mid-20th century, but over the last few
years it's made a comeback. Now it's hip to be wireless once again
thanks to the Internet.
Back in 2007, approximately half of all the world's
Internet users were using some kind of wireless access.
Today, over 80 percent of us use wireless to get online at home,
which is hardly surprising now
more of us are using smartphones and tablets (54 percent) than desktop computers (46 percent).
Wireless, mobile Internet is overwhelmingly popular
in developing countries where traditional wired
forms of access, based on telephone
networks, are not available.
Wireless Internet, perhaps best known to us as Wi-Fi®, has made the Internet more
convenient than ever before. But what makes it different from ordinary Internet access?
From radio to Wi-Fi
Radio is an invisible game of throw-and-catch. Instead of throwing a ball from one person to another, you send information, coded as a pattern of electricity and magnetism, from a transmitter (the thrower) to a receiver (the catcher)—both of which are kinds of antennas. The transmitter is
a piece of equipment that turns electrical signals (such as the sound of someone
speaking, in radio, or a picture, in TV) into an oscillating
electromagnetic wave that
beams through the air, in a straight line, at the speed
of light (300,000 km 186,000 miles per second). The receiver
is a mirror-image piece of equipment that catches the waves and turns them
back into electrical signals—so we can recreate the radio sounds or TV
pictures. The more powerful the transmitter and receiver, the further
apart they can be spaced. Radio stations use gigantic transmitters, and
that's why we can pick up radio signals from thousands of miles away on
the opposite side of Earth. Wireless Internet is simply a way of using radio waves to send and
receive Internet data instead of radio sounds or TV pictures. But,
unlike radio and TV, it is typically used to send signals only over
relatively short distances with low-power transmitters.
Artwork: The basic concept of radio: sending messages from a transmitter to a receiver
at the speed of light using radio waves. In wireless Internet, the communication is two-way: there's a transmitter
and receiver in both your computer (or handheld device) and the piece of equipment (such as a router) that connects
you to the Internet.
What is Wi-Fi?
If you have wireless Internet access at home, you probably have a
little box called a router that plugs into
socket. This kind of router is a bit like a sophisticated modem: it's a standalone
computer whose job is to relay connections to and from the Internet. At
home, you might use a router to connect several computers to the
Internet at once (saving on the need for several separate modems). In
other words, the router does two jobs: it creates a wireless
linking all your computers together, and it also gives all your
machines a shared gateway to the Internet.
Charts: There's been huge worldwide growth in cellphones (mobile phones) and wireless Internet access over the last couple of decades, particularly in developing countries. In 2000, there were 0.7 billion cellphone subscriptions worldwide and 71 percent of them were in high-income (developed) countries. By 2019, the position had reversed: there were over 11 times more subscriptions (roughly 8.1 billion) and over 80 percent of them were in developing countries. The implications for Internet access are obvious: more and more people are going online from wireless mobile devices, especially in the developing world.
Sources: 2012 Information and Communications for Development: Maximizing Mobile, World Bank, 2012; Measuring the Information Society Report 2018, ITU-T, 2019.
You can connect a router to all your different computers using
ordinary network-connecting cables (for the technically minded, these
are called RJ-45, Cat 5, or Ethernet cables). This creates what's
called a LAN (local area network) linking the machines together. A computer
network is a very orderly affair, more like an organized committee
meeting, with carefully agreed rules of behavior, than a free-for-all
cocktail party. The machines on the
network have to be hooked up in a standard way and they communicate in
a very orderly fashion. The rules that govern the network setup and the
communication are based on an international standard called
Ethernet (also known as IEEE 802.3).
A wireless router is simply a router that connects to your computer
(or computers) using radio waves instead of cables. It
contains a very low-power radio transmitter and receiver, with a
maximum range of about 90 meters or 300 ft, depending on what your
walls are made of and what other electrical equipment is nearby. The
router can send and receive Internet data to any computer in your home
also equipped with wireless access (so each computer on the wireless
network has to have a radio transmitter and receiver in it too). Most
new laptops come with wireless cards built in. For older laptops, you
can usually plug a wireless adapter card into the PCMCIA or USB socket.
In effect, the router becomes an informal access point
for the Internet, creating an invisible "cloud" of wireless connectivity all
around it, known as a hotspot. Any computer
inside this cloud can connect into the network, forming a wireless LAN.
Photo: If your laptop doesn't have a built-in Wi-Fi card, you
can plug in a PCMCIA adapter card like this one. They're relatively inexpensive,
especially if you get them on eBay. But beware: older PCMCIA cards may not support
newer forms of wireless security such as WPA.
Just as computers connected to a wired LAN use Ethernet, machines on a wireless LAN use
the wireless equivalent, which is called Wi-Fi
(or, more technically, IEEE 802.11). Wireless Internet
is improving all the time, so better forms of Wi-Fi are constantly
evolving. You may see wireless equipment marked 802.11a, 802.11b,
802.11g or 802.11n: these are all broadly compatible variants of
802.11, with 802.11n, 802.11g and 802.11a somewhat faster than 802.11b.
Other more recent variants are named 802.11a with an extra letter added
on the end (such as 802.11ax, 802.11ay, and so on).
For example, 802.11ah is designed to work with the so-called
Internet of Things, 802.11ax is for high-efficiency LANs, and
802.11az is concerned with "location services" (finding the accurate position
of mobile devices).
Wi-Fi is where the expression Wi-Fi hotspot
comes from. A Wi-Fi hotspot is simply a public place where you can connect your
computer wirelessly to the Internet. The hotspots
you find in airports, coffee bars, bookshops, and college campuses use
one or more wireless routers to create wireless Net access over a large
area. Even bigger networks can be created by using tens or hundreds of
access points to span entire university campuses, for example.
Since the mid-2000s, many cities worldwide have
turned huge areas into public hotspots (an idea sometimes known
as Municipal Wi-Fi, Muni Wi-Fi, or Muni-Fi). Wi-Fi hotspots continue to pop up all over the world and the number
is growing at an astonishing rate. By 2007, there were estimated to be around 180,000 in the United States
alone; at the time this artice was last updated (September 2020), according to
Statista, the worldwide total was
around 362 million.
Wi-Fi Direct®: Let's cut out the middleman!
People sometimes confuse Wi-Fi and Bluetooth. Both are
methods of connecting gadgets without wires, so what exactly is the
difference? Broadly speaking, Bluetooth is a way of connecting two relatively
nearby gadgets without the hassle of using a cable, whereas Wi-Fi is
a method of linking wireless computers (and particularly mobile ones, such as
laptops, tablets, and smartphones) to the Internet through a shared
connection point—your router—which typically makes a wired
connection to a telephone or cable line. At least, that's how things
used to be.
Artwork: Wi-Fi modes: Left: In infrastructure mode, all your devices communicate wirelessly with a central router that talks (usually via a wired connection) to the Internet. Here, three tablets and a laptop are talking to a router in the middle. Right: In ad-hoc mode (or with Wi-Fi Direct), devices communicate directly over a temporary network without any kind of central router. In this example, two tablets are talking to one another and to a shared printer using Wi-Fi Direct.
But nothing says Wi-Fi can't also link two laptops or smartphones
directly instead of Bluetooth. Normally, Wi-Fi uses infrastructure mode, in which various gadgets and devices communicate
through a router or central access point. But Wi-Fi also has
what's called an ad-hoc mode, which allows gadgets to communicate directly
without a router. Typically, an ad-hoc network is created as a temporary form of communication—as the name
ad-hoc suggests—whereas infrastructure-mode is a more permanent
thing. (The Wi-Fi network I'm using at the moment, for example, is
one I set up about a decade ago using infrastructure mode and a
central router as the access point.) Ad-hoc networks tend to be hard
to set up, slower, and less reliable because the various devices
using them all have to communicate with each other and manage
the networking (unlike infrastructure networks, which are managed by
the router that also handles the communications between them).
Some household gadgetry relies on a mixture of Wi-Fi and
Bluetooth, which can be a bit confusing—and prompts the question
"Why can't Wi-Fi do the short-range, ad-hoc bit as well?" With a
bolt-on addition to the basic Wi-Fi spec known as Wi-Fi Direct®, it
can. The basic idea is to use secure, encrypted Wi-Fi in a much more
informal way for things like printing from a tablet or sharing photos
with someone else's smartphone. Putting it a bit more technically, Wi-Fi
Direct is an ad-hoc, peer-to-peer form of networking between pairs of
nearby devices (sometimes multiple devices) that doesn't rely on an
Internet connection. It works in a similar way to traditional Wi-Fi:
each device lets others nearby know that
you can connect to it (much like the way access points let you know
about available Wi-Fi networks nearby). Some devices can connect both to Wi-Fi Direct
and a Wi-Fi network at the same time; others can only do one or the
other at a time.
Wi-Fi or Bluetooth?
How does Wi-Fi Direct compare to Bluetooth? It's up to 10 times
faster at transferring data (250mbps compared to 25mbps) and
has a range several times longer (up to 200m or 650ft compared to a maximum of about 60m or 200ft for Bluetooth).
Although both are secure, Wi-Fi Direct uses Wi-Fi's WPA-2 encryption, which uses twice
as many bits (256) as Bluetooth's (128 bit) and is theoretically
much more secure. In Bluetooth's favor, it allows more devices to connect at once, and while its shorter range might
seem like a drawback, it means it uses less power than Wi-Fi
(an extremely important consideration for mobile devices).
WAP and i-mode
Photo: State-of-the-art Web browsing c.2002 on an old-fashioned cellphone! This phone is using WAP to browse breaking news on a website called Ananova. Note the crude, monochrome text-only screen. What you can't see here is the grindingly slow speed, which was about 5 times slower even than old-fashioned, dialup Internet access.
Photo: Mobile broadband (with a smartphone or USB modem) is the fastest growing form of wireless Internet. The worldwide market grew 12-fold between 2007 and 2015
(according to 2015 figures from the ITU-T) and topped 5.3 billion users in early 2019 (according to 2018 ITU-T data).
Wi-Fi isn't the only way to access the Internet wirelessly. If you
have a smartphone (an advanced kind of cellphone), such as
an iPhone or an Android, it'll have a miniature Web browser that works
in exactly the same way as the one you'd find on a laptop (albeit using a much smaller screen).
In the late 1990s and early 2000s, some cellphones had very crude built-in web browsers that could
haul up simplified, text-versions of web pages using a system called WAP (technically known as
Wireless Application Protocol, though no-one ever called it that). WAP was very slow
to take off and has now been rendered obsolete by faster cellphone networks and smartphones.
While Europe and North America were struggling with WAP, Japan's cellphone users already had a much better version of cellphone Internet called i-mode that offered fast access to web pages and emails. i-mode was always more popular than WAP and was gradually exported to a number of other countries. However, it too has now been superseded by better technologies based on faster 3G and 4G (third- and fourth-generation) cellphone networks. Effectively, mobile and desktop Internet have now converged: thanks to wireless, and the arrival of easy-to-use apps tailored to mobile devices, it's as easy to do things on your cellphone or tablet computer as it is on your desktop PC.
MiFi, tethering, and mobile broadand
Artwork: Tethering: Your laptop connects to your cellphone over Wi-Fi (red). Your phone connects
to a 3G, 4G, or 5G cellphone network (blue). That network hooks into the public telephone network and the Internet's
mail, web, and other servers using a mixture of fiber-optic and wired connections (orange).
If you find yourself in a rural area, far from a decent broadband connection and any Wi-Fi hotspots, how can you get fast access
to the Internet? You can use your smartphone over a cellphone network, but what if you want to go online with a full-scale laptop
and the only form of connection it has is Wi-Fi? One easy option is to set up your smartphone as a hotspot, so your phone goes online using a 3G or (ideally) 4G cellphone network and your laptop connects to your phone using Wi-Fi, in the normal way. That's called tethering. Although it's relatively simple and convenient, it can work out very expensive, so check the allowances in your
cellphone package or plan before you rely on it too much. Another option is to get yourself a little cellphone-like device that can do this kind of trick permanently; you'll find those marketed using the name MiFi (mobile Wi-Fi—without the hyphen). Typically, MiFi devices are small and battery powered and give a few hours of Internet access before they need recharging.
Another option is to use a plug-in cellphone-type modem that connects your machine directly to the Internet over a cellphone
network, which is called mobile broadband. If you want to find out more about that, please see our separate article on broadband and mobile broadband.
How to secure a home wireless network
If you've set up your home wireless network, you've probably noticed something: your neighbors
have all got them too! Not only that, you could quite easily connect to someone else's
network if it weren't secured properly—and by the same token, they could connect
to your network too. So how do you secure a network? We suggest:
Make sure you secure your network (with what's called a pre-shared key or PSK). Use the strongest form of security your hardware supports: use WPA2 rather than WPA and use WPA in preference to WEP.
Choose a nontrivial password (and certainly not something your neighbors could easily guess, like your surname). At the very least, if you're going to use an easy-to-remember password, put a special character ($, %, and so on) at the beginning or the end of it—you'll make it vastly more secure.
Set up your network to use an access control list (ACL). This is a list of specific, trusted computers that will be allowed to connect to your network. For each computer on the list, you'll need to specify what's called its MAC address (or LAN MAC address). You'll find the MAC address written on the bottom of a laptop computer, round the back of a desktop, or on the bottom of a plug-in PCMCIA network card.
If you have only one computer and it never moves from your desktop, which is reasonably close to your router, don't use wireless at all. Connect with an Ethernet cable instead and use your network in wired mode. It'll be faster as well as more secure.
You could make your network a "hidden" one (in other words, so the network name (SSID) is not broadcast). Only people who know the network name can connect by typing in the correct SSID and password. Hidden networks can be problematic with some older operating
systems, so you'll need to test whether yours works. Opinions vary on whether hidden networks do anything for security. Some people claim they are more secure; others say they have security risks.
1888: German physicist Heinrich Hertz (1857–1894) makes the first electromagnetic radio waves in his lab.
1894: British physicist Sir Oliver Lodge (1851–1940) sends the first message using radio waves in Oxford, England.
1899: Italian inventor Guglielmo Marconi (1874–1937) sends radio waves across the English Channel. By 1901.
Marconi has sent radio waves across the Atlantic, from Cornwall in England to Newfoundland.
1940s: Taxi firms begin using two-way radios.
1944: Hedy Kiesler Markey (better known as the actress Hedy Lamarr) and George Antheil patent spread spectrum frequency hopping, a way of making wireless communication more reliable and secure by transmitting and receiving on different radio frequencies.
1970s: First analog cellphones appear, developed in Chicago by Illinois Bell and AT&T.
1980s: GSM (Global System for Mobile communications) digital cellphones appears in Europe, followed by PCS (Personal Communications
Services) phones in the United States.
1990: A working group of wireless experts begins work drafting the standard that will become Wi-Fi.
1994: Nokia, Finnish cellphone maker, sends data over a cellphone network.
1994: Phone.com develops WAP in the United States.
1997: Wi-Fi standard (IEEE 802.11) is agreed internationally.
1998: The name "Bluetooth" is officially adopted for a proposed new kind of short-distance wireless link.
1999: Japanese telecommunications company NTT DoCoMo develops i-mode.
1999: Steve Jobs of Apple Computer decides to incorporate a version of Wi-Fi called AirPort into the iBook laptop, effectively making it the first mass-market Wi-Fi product.
2000: The first Bluetooth headset goes on sale.
2005: Wi-Fi is officially added to Webster's Dictionary by Merriam-Webster.
2007: Apple Computer releases its iPhone—tilting the balance of power from desktop PCs and wired Internet to mobile devices and wireless Internet.
2010: Apple releases the iPad tablet, giving users all the convenience of a wireless smartphone with a bigger display closer to that of a desktop PC.
2015: Google announces its Mobile-Friendly algorithm update, rewarding websites that reformat themselves appropriately for smartphones.
2015: Wi-Fi celebrates its 25th birthday! By the end of 2015, there are 7 billion wireless, cellphone subscriptions.
2018: ITU-T predicts mobile broadband subscriptions will reach 5.3 billion (in other words, in theory, over half the world's population has reasonably fast mobile Internet access).
2019: According to the ITU-T, 51.2 percent of the world population (3.9 people) are now using the Internet.
Great progress has been made, but many of the world's people remain offline.
If Your Wi-Fi Is Terrible, Check Your Router by Brian X. Chen. The New York Times. October 7, 2015. If you've never upgraded your router, now might be the time; newer routers are faster, more reliable, and work better over longer ranges with multiple devices connected.
What's Next After 25 Years of Wi-Fi? by Jeremy Hsu. IEEE Spectrum, September 10, 2015. An interview with Dorothy Stanley, vice chair of the IEEE 802.11 Working Group, describing where Wi-Fi is likely to go next.
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