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Free Wi-Fi poster at Bristol Temple Meads railway station, England

Wireless Internet

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: Most of us expect to find decent wireless Internet access in public places like this British railroad station. Although Wi-Fi was invented in 1999, public Wi-Fi hotspots like this really took off when smartphones first hit the market in 2007.

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  1. From wireless to radio
  2. From radio to Wi-Fi
  3. What is Wi-Fi?
  4. Wi-Fi Direct®: Let's cut out the middleman!
  5. WAP and i-mode
  6. MiFi, tethering, and mobile broadand
  7. How to secure a home wireless network
  8. A brief history of wireless
  9. Find out more

From wireless to radio

Wireless started out as a way of sending audio programs through the air. 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 82 percent of us use wireless to get online at home, which is hardly surprising now more of us are using smartphones and tablets (56 percent) than desktop computers (44 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 showing how antennas transmit and receive radio waves

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.

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What is Wi-Fi?

If you have wireless Internet access at home, you probably have a little box called a router that plugs into your telephone 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 computer network, linking all your computers together, and it also gives all your machines a shared gateway to the Internet.

A wireless broadband Netgear router

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.

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).

Netgear PCMCIA laptop wireless card

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.

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 that is 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.

A disassembled wireless WiFi PCMCIA card showing the circuit board, antenna, and other component parts inside

Photo: What's inside a Wi-Fi card? Take apart a PCMCIA card, like the one above, and you'll find something like this. Note the gold-colored antenna at the bottom. The top and bottom case is on the left.

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 (December 2021), according to Statista, the worldwide total was around 540 million.

Pie charts showing the growth in mobile cellphone subscriptions in developed and developing countries

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 2005, there were about a billion cellphone subscriptions worldwide and 71 percent of them were in high-income (developed) countries. By 2020, 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. Source: Drawn in 2021 using November 2020 data from International Telecommunications Union (ITU).

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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.

Ad-hoc networks

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).

Comparison between Wi-Fi infrastructure and ad-hoc modes and Wi-Fi Direct

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.

Wi-Fi Direct®

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

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.

Browsing a cellphone with WAP

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.

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

HSDPA mobile broadband modem or dongle made by ZTE

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). By 2021, ITU-T estimates suggested 95 percent of the world's population were living in range of a mobile broadband network.

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.

How tethering connects your laptop to the Internet

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).

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

Ethernet networking cable in close-up

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:

A brief history of wireless

Guglielmo Marconi.

Photo: One of the original pioneers of wireless, Guglielmo Marconi. Photo courtesy of US Library of Congress

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Articles from this website are registered at the US Copyright Office. Copying or otherwise using registered works without permission, removing this or other copyright notices, and/or infringing related rights could make you liable to severe civil or criminal penalties.

Text copyright © Chris Woodford 2007, 2021. All rights reserved. Full copyright notice and terms of use.

Wi-Fi and Wi-Fi Direct are registered trademarks of Wi-Fi Alliance.

Bluetooth is a registered trademark of Bluetooth SIG, Inc.

MiFi is a registered trademark of Novatel Wireless, Inc. in the United States; in the United Kingdom, MiFi is a registered trademark of Hutchison 3G UK Ltd.

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