If you've been in an airport, coffee shop, library or hotel recently, chances are you've been right in the middle of a wireless network. Many people also use wireless networking, also called WiFi or 802.11 networking, to connect their computers at home, and some cities are trying to use the technology to provide free or low-cost Internet access to residents. In the near future, wireless networking may become so widespread that you can access the Internet just about anywhere at any time, without using wires.

One wireless router can allow multiple devices to connect to the Internet.

WiFi has a lot of advantages. Wireless networks are easy to set up and inexpensive. They're also unobtrusive -- unless you're on the lookout for a place to use your laptop, you may not even notice when you're in a hotspot. In this article, we'll look at the technology that allows information to travel over the air. We'll also review what it takes to create a wireless network in your home.
First, let's go over a few WiFi basics.

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A wireless network uses radio waves, just like cell phones, televisions and radios do. In fact, communication across a wireless network is a lot like two-way radio communication. Here's what happens:

1. A computer's wireless adapter translates data into a radio signal and transmits it using an antenna.
2. A wireless router receives the signal and decodes it. The router sends the information to the Internet using a physical, wired Ethernet connection.

The process also works in reverse, with the router receiving information from the Internet, translating it into a radio signal and sending it to the computer's wireless adapter. The radios used for WiFi communication are very similar to the radios used for walkie-talkies, cell phones and other devices. They can transmit and receive radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves back into 1s and 0s. But WiFi radios have a few notable differences from other radios:

• They transmit at frequencies of 2.4 GHz or 5 GHz. This frequency is considerably higher than the frequencies used for cell phones, walkie-talkies and televisions. The higher frequency allows the signal to carry more data.
• They use 802.11 networking standards, which come in several flavors:
  • 802.11a transmits at 5 GHz and can move up to 54 megabits of data per second. It also uses orthogonal frequency-division multiplexing (OFDM), a more efficient coding technique that splits that radio signal into several sub-signals before they reach a receiver. This greatly reduces interference.
    
  • 802.11b is the slowest and least expensive standard. For a while, its cost made it popular, but now it's becoming less common as faster standards become less expensive. 802.11b transmits in the 2.4 GHz frequency band of the radio spectrum. It can handle up to 11 megabits of data per second, and it uses complementary code keying (CCK) modulation to improve speeds.
  • 802.11g transmits at 2.4 GHz like 802.11b, but it's a lot faster -- it can handle up to 54 megabits of data per second. 802.11g is faster because it uses the same OFDM coding as 802.11a.
  • 802.11n is the newest standard that is widely available. This standard significantly improves speed and range. For instance, although 802.11g theoretically moves 54 megabits of data per second, it only achieves real-world speeds of about 24 megabits of data per second because of network congestion. 802.11n, however, reportedly can achieve speeds as high as 140 megabits per second. The standard is currently in draft form -- the Institute of Electrical and Electronics Engineers (IEEE) plans to formally ratify 802.11n by the end of 2009.
• Other 802.11 standards focus on specific applications of wireless networks, like wide area networks (WANs) inside vehicles or technology that lets you move from one wireless network to another seamlessly.
• WiFi radios can transmit on any of three frequency bands. Or, they can "frequency hop" rapidly between the different bands. Frequency hopping helps reduce interference and lets multiple devices use the same wireless connection simultaneously.

Other Wireless Networking Standards Another wireless standard with a slightly different number, 802.15, is used for Wireless Personal Area Networks (WPANs). It covers a very short range and is used for Bluetooth technology. WiMax, also known as 802.16, looks to combine the benefits of broadband and wireless. WiMax will provide high-speed wireless Internet over very long distances and will most likely provide access to large areas such as cities.

As long as they all have wireless adapters, several devices can use one router to connect to the Internet. This connection is convenient, virtually invisible and fairly reliable; however, if the router fails or if too many people try to use high-bandwidth applications at the same time, users can experience interference or lose their connections.
Next, we'll look at how to connect to the Internet from a WiFi hotspot.

What's in a Name? You may be wondering why people refer to WiFi as 802.11 networking. The 802.11 designation comes from the IEEE. The IEEE sets standards for a range of technological protocols, and it uses a numbering system to classify these standards.

If you want to take advantage of public WiFi hotspots or start a wireless network in your home, the first thing you'll need to do is make sure your computer has the right gear. Most new laptops and many new desktop computers come with built-in wireless transmitters. If your laptop doesn't, you can buy a wireless adapter that plugs into the PC card slot or USB port. Desktop computers can use USB adapters, or you can buy an adapter that plugs into the PCI slot inside the computer's case. Many of these adapters can use more than one 802.11 standard.

USB wireless adapter and PC wireless card photos courtesy Consumer Guide Products Wireless adapters can plug into a computer's PC card slot or USB port.

Once you've installed your wireless adapter and the drivers that allow it to operate, your computer should be able to automatically discover existing networks. This means that when you turn your computer on in a WiFi hotspot, the computer will inform you that the network exists and ask whether you want to connect to it. If you have an older computer, you may need to use a software program to detect and connect to a wireless network.
Being able to connect to the Internet in public hotspots is extremely convenient. Wireless home networks are convenient as well. They allow you to easily connect multiple computers and to move them from place to place without disconnecting and reconnecting wires. In the next section, we'll look at how to create a wireless network in your home.


If you already have several computers networked in your home, you can create a wireless network with a wireless access point. If you have several computers that are not networked, or if you want to replace your Ethernet network, you'll need a wireless router. This is a single unit that contains:

1. A port to connect to your cable or DSL modem
2. A router
3. An Ethernet hub
4. A firewall
5. A wireless access point

A wireless router allows you to use wireless signals or Ethernet cables to connect your computers to one another, to a printer and to the Internet. Most routers provide coverage for about 100 feet (30.5 meters) in all directions, although walls and doors can block the signal. If your home is very large, you can buy inexpensive range extenders or repeaters to increase your router's range.

Photo courtesy Consumer Guide Products A wireless router uses an antenna to send signals to wireless devices and a wire to send signals to the Internet.

As with wireless adapters, many routers can use more than one 802.11 standard. 802.11b routers are slightly less expensive, but because the standard is older, they're slower than 802.11a, 802.11g and 802.11n routers. Most people select the 802.11g option for its speed and reliability.
Once you plug in your router, it should start working at its default settings. Most routers let you use a Web interface to change your settings. You can select:

• The name of the network, known as its service set identifier (SSID) -- The default setting is usually the manufacturer's name.
• The channel that the router uses -- Most routers use channel 6 by default. If you live in an apartment and your neighbors are also using channel 6, you may experience interference. Switching to a different channel should eliminate the problem.
• Your router's security options -- Many routers use a standard, publicly available sign-on, so it's a good idea to set your own username and password.

Security is an important part of a home wireless network, as well as public WiFi hotspots. If you set your router to create an open hotspot, anyone who has a wireless card will be able to use your signal. Most people would rather keep strangers out of their network, though. Doing so requires you to take a few security precautions.
It's also important to make sure your security precautions are current. The Wired Equivalency Privacy (WEP) security measure was once the standard for WAN security. The idea behind WEP was to create a wireless security platform that would make any wireless network as secure as a traditional wired network. But hackers discovered vulnerabilities in the WEP approach, and today it's easy to find applications and programs that can compromise a WAN running WEP security.
To keep your network private, you can use one of the following methods:

• WiFi Protected Access (WPA) is a step up from WEP and is now part of the 802.11i wireless network security protocol. It uses temporal key integrity protocol (TKIP) encryption. As with WEP, WPA security involves signing on with a password. Most public hotspots are either open or use WPA or 128-bit WEP technology, though some still use the vulnerable WEP approach.
• Media Access Control (MAC) address filtering is a little different from WEP or WPA. It doesn't use a password to authenticate users -- it uses a computer's physical hardware. Each computer has its own unique MAC address. MAC address filtering allows only machines with specific MAC addresses to access the network. You must specify which addresses are allowed when you set up your router. This method is very secure, but if you buy a new computer or if visitors to your home want to use your network, you'll need to add the new machines' MAC addresses to the list of approved addresses. The system isn't foolproof. A clever hacker can spoof a MAC address -- that is, copy a known MAC address to fool the network that the computer he or she is using belongs on the network.

­Wireless networks are easy and inexpensive to set up, and most routers' Web interfaces are virtually self-explanatory.

You and millions of other people around the world use the Internet every day -- to communicate with others, follow the stock market, keep up with the news, check the weather, make travel plans, conduct business, shop, entertain yourself and learn. Staying connected has become so important that it's hard to get away from your computer and your Internet connection because you might miss an e-mail message, an update on your stock or some news you need to know. With your business or your personal life growing more dependent on electronic communication over the Internet, you might be ready to take the next step and get a device that allows you to access the Internet on the go.

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Wireless Internet can be built into your cell phone or received through a wireless card.

That's where wireless Internet comes in. You've probably seen news or advertising about cell phones and PDAs that let you receive and send e-mail. This seems a logical next step, but there are some questions that come up when you think about going mobile with the Internet. Will you still be able to surf the Web? How fast will you be able to get the information you need? You might have heard of the Wireless Application Protocol (WAP) and wonder how it works. Learn just what WAP is, why it is needed and what devices use it.



Probably the most important factor in the birth of wireless Internet has been the proliferation of digital cell phones in the last few years. The expanding network of digital cellular and personal communication services (PCS) has created a solid foundation for wireless Internet services. It is estimated that there are more than 50 million Web-enabled cell phones in use. In 1997, Nokia, Motorola, Ericsson and Phone.com came together to create the WAP because they believed that a universal standard is critical to the successful implementation of wireless Internet. Since then, more than 350 companies have joined them in the WAP Forum.

2008 HowStuffWorks
A typical cell phone

Making a Web site accessible through a wireless device is quite a challenge. So far, only a small portion of the more than a billion Web sites provide any wireless Internet content. As the use of WAP-enabled devices grows, you can expect that many more Web sites will be interested in creating wireless content.
WAP is designed to work on any of the existing wireless services, using standards such as:

• Short Message Service (SMS)
• High-Speed Circuit-Switched Data (CSD)
• General Packet Radio Service (GPRS)
• Unstructured Supplementary Services Data (USSD)

For more information, on these services, check out this page.

WAP uses Wireless Markup Language (WML), which includes the Handheld Device Markup Language (HDML) developed by Phone.com.
WML can also trace its roots to eXtensible Markup Language (XML). A markup language is a way of adding information to your content that tells the device receiving the content what to do with it. The best known markup language is Hypertext Markup Language (HTML). Unlike HTML, WML is considered a meta language. Basically, this means that in addition to providing predefined tags, WML lets you design your own markup language components. WAP also allows the use of standard Internet protocols such as UDP, IP and XML.
There are three main reasons why wireless Internet needs the Wireless Application Protocol:

• Transfer speed
• Size and readability
• Navigation

Most cell phones and Web-enabled PDAs have data transfer rates of 14.4 Kbps or less. Compare this to a typical 56 Kbps modem, a cable modem or a DSL connection. Most Web pages today are full of graphics that would take an unbearably long time to download at 14.4 Kbps. Wireless Internet content is typically text-based in order to solve this problem.

The main Amazon page for regular Internet

The main Amazon page for wireless Internet

The relatively small size of the LCD on a cell phone or PDA presents another challenge. Most Web pages are designed for a resolution of 640x480 pixels, which is fine if you are reading on a desktop or a laptop. The page simply does not fit on a wireless device's display, which might be 150x150 pixels. Also, the majority of wireless devices use monochrome screens. Pages are harder to read when font and background colors become similar shades of gray.
Navigation is another issue. You make your way through a Web page with points and clicks using a mouse; but if you are using a wireless device, you often use one hand to scroll keys.
WAP takes each of these limitations into account and provides a way to work with a typical wireless device.


Here's what happens when you access a Web site using a WAP-enabled device:

• You turn on the device and open the minibrowser.
• The device sends out a radio signal, searching for service.
• A connection is made with your service provider.
• You select a Web site that you wish to view.
• A request is sent to a gateway server using WAP.
• The gateway server retrieves the information via HTTP from the Web site.
• The gateway server encodes the HTTP data as WML.
• The WML-encoded data is sent to your device.
• You see the wireless Internet version of the Web page you selected.

To create wireless Internet content, a Web site creates special text-only or low-graphics versions of the site. The data is sent in HTTP form by a Web server to a WAP gateway. This system includes the WAP encoder, script compiler and protocol adapters to convert the HTTP information to WML. The gateway then sends the converted data to the WAP client on your wireless device.
What happens between the gateway and the client relies on features of different parts of the WAP protocol stack. Let's take a look at each part of the stack:

WAP protocol stack

• WAE - The Wireless Application Environment holds the tools that wireless Internet content developers use. These include WML and WMLScript, which is a scripting language used in conjunction with WML. It functions much like Javascript.
• WSP - The Wireless Session Protocol determines whether a session between the device and the network will be connection-oriented or connectionless. What this is basically talking about is whether or not the device needs to talk back and forth with the network during a session. In a connection-oriented session, data is passed both ways between the device and the network; WSP then sends the packet to the Wireless Transaction Protocol layer (see below). If the session is connectionless, commonly used when information is being broadcast or streamed from the network to the device, then WSP redirects the packet to the Wireless Datagram Protocol layer (see below).
• WTP - The Wireless Transaction Protocol acts like a traffic cop, keeping the data flowing in a logical and smooth manner. It also determines how to classify each transaction request:
  • Reliable two-way
  • Reliable one-way
  • Unreliable one-way
  The WSP and WTP layers correspond to Hypertext Transfer Protocol (HTTP) in the TCP/IP protocol suite.
  
• WTLS - Wireless Transport Layer Security provides many of the same security features found in the Transport Layer Security (TLS) part of TCP/IP. It checks data integrity, provides encryption and performs client and server authentication.
• WDP - The Wireless Datagram Protocol works in conjunction with the network carrier layer (see below). WDP makes it easy to adapt WAP to a variety of bearers because all that needs to change is the information maintained at this level.
• Network carriers - Also called bearers, these can be any of the existing technologies that wireless providers use, as long as information is provided at the WDP level to interface WAP with the bearer.

Once the information is received by the WAP client, it is passed to the minibrowser. This is a tiny application built into the wireless device that provides the interface between the user and the wireless Internet. Here's a look at the start page of a typical minibrowser:

The minibrowser offers streamlined functionality.

The minibrowser does not offer anything more than basic navigation. Wireless Internet is still a long way from being a true alternative to the normal Internet. It is really positioned right now for people who need the ability to connect no matter where they are. The WAP Forum is continually working on the specifications of the WAP standard to ensure that it evolves in a timely and useful manner.

The word on just about every Internet user's lips these days is "broadband." We have so much more data to send and download today, including audio files, video files and photos, that it's clogging our wimpy modems. Many Internet users are switching to cable modems and digital subscriber lines (DSLs) to increase their bandwidth. There's also a new type of service being developed that will take broadband into the air.

Photo courtesy Angel Technologies This diagram shows how the HALO Network will enable a high-speed wireless Internet connection

At least three companies are planning to provide high-speed wireless Internet connection by placing aircraft in fixed patterns over hundreds of cities. Angel Technologies is planning an airborne Internet network, called High Altitude Long Operation (HALO), which would use lightweight planes to circle overhead and provide data delivery faster than a T1 line for businesses. Consumers would get a connection comparable to DSL. Also, AeroVironment has teamed up with NASA on a solar-powered, unmanned plane that would work like the HALO network, and Sky Station International is planning a similar venture using blimps instead of planes.
We've already seen satellites used for broadband Internet access. In this edition of How Stuff WILL Work, you'll learn about the future of the airborne Internet. We'll take a look at the networks in development, the aircraft and how consumers may use this technology in their homes.


The computer most people use comes with a standard 56K modem, which means that in an ideal situation your computer would downstream at a rate of 56 kilobits per second (Kbps). That speed is far too slow to handle the huge streaming-video and music files that more consumers are demanding today. That's where the need for bigger bandwidth -- broadband -- comes in, allowing a greater amount of data to flow to and from your computer. Land-based lines are limited physically in how much data they can deliver because of the diameter of the cable or phone line. In an airborne Internet, there is no such physical limitation, enabling a broader capacity. Several companies have already shown that satellite Internet access can work. The airborne Internet will function much like satellite-based Internet access, but without the time delay. Bandwidth of satellite and airborne Internet access are typically the same, but it will take less time for the airborne Internet to relay data because it is not as high up. Satellites orbit at several hundreds of miles above Earth. The airborne-Internet aircraft will circle overhead at an altitude of 52,000 to 69,000 feet (15,849 to 21,031 meters). At this altitude, the aircraft will be undisturbed by inclement weather and flying well above commercial air traffic.
Networks using high-altitude aircraft will also have a cost advantage over satellites because the aircraft can be deployed easily -- they don't have to be launched into space. However, the airborne Internet will actually be used to compliment the satellite and ground-based networks, not replace them. These airborne networks will overcome the last-mile barriers facing conventional Internet access options. The "last mile" refers to the fact that access to high-speed cables still depends on physical proximity, and that for this reason, not everyone who wants access can have it. It would take a lot of time to provide universal access using cable or phone lines, just because of the time it takes to install the wires. An airborne network will immediately overcome the last mile as soon as the aircraft takes off.
The airborne Internet won't be completely wireless. There will be ground-based components to any type of airborne Internet network. The consumers will have to install an antenna on their home or business in order to receive signals from the network hub overhead. The networks will also work with established Internet Service Providers (ISPs), who will provide their high-capacity terminals for use by the network. These ISPs have a fiber point of presence -- their fiber optics are already set up. What the airborne Internet will do is provide an infrastructure that can reach areas that don't have broadband cables and wires.

Photo courtesy Angel Technologies Airborne-Internet systems will require that an antenna be attached to the side of your house or work place.

In the next three sections, we will take a look at the three aircraft that could be bringing you broadband Internet access from the sky.


One the three companies developing an airborne Internet network is Angel Technologies. Its HALO Network may be ready for deployment at the end of 2003 and in place over 10 cities by 2006. The centerpiece of this network is the Proteus plane, which will carry wireless networking equipment into the air.

Photo courtesy Angel Technologies The Proteus plane will carry the network hub for the HALO Network.

The Proteus plane was developed by Scaled Composites. It is designed with long wings and the low wing loading needed for extended high-altitude flight. Wing loading is equal to the entire mass of the plane divided by its wing area. Proteus will fly at heights of 9.5 and 11.4 miles (15.3 and 18.3 km) and cover an area up to 75 miles (120.7 km) in diameter. The plane still needs to receive approval from the Federal Aviation Administration.

Proteus Aircraft
Weight	9,000 pounds at takeoff 5,900 pounds empty
Wingspan	77 ft 7 inches (23.7 m) Expandable to 92 feet (28 m)
Length	56.3 ft (17.2 m)
Height	17.6 ft (5.4 m)
Engines	2 turbofan engines 2,300 pounds of thrust
Range	18 hours
Speed	65 knots (75 mph/120.7 kph) to 250 knots (288 mph/463.5 kph)

At the heart of Angel's Proteus planes is the one-ton airborne-network hub, which is what allows the plane to relay data signals from ground stations to your workplace and home computer. The airborne-network hub consists of an antenna array and electronics for wireless communication. The antenna array creates hundreds of virtual cells, like mobile-phone cells, on the ground to serve thousands of users. The payload is liquid-cooled and operates off of about 20 kilowatts of DC power. An 18-foot dish underneath the plane is responsible for reflecting high-speed data signals from a ground station to your computer.
Each city in the HALO Network will be allotted three piloted Proteus planes. Each plane will fly for eight hours before the next plane takes off. Angel CEO Marc Arnold says his company has identified 3,500 airports in the United States that can meet HALO's operational needs. After takeoff, the Proteus plane will climb to a safe altitude, above any bad weather or commercial traffic, and begin an 8-mile loop around the city. Each plane will accommodate two pilots, who will split flying duties during their eight-hour flight.


Sky Station International is counting on its blimps to beat Angel to the punch in the race to deliver high-speed Internet access from high altitudes. Sky Station calls its blimps lighter-than-air platforms, and plans to station these airships over at least 250 cities worldwide, one over each city. Each station would fly at an altitude of 13 miles (21 km) and provide wireless service to an area of approximately 7,500 square miles (19,000 square km).

Sky Station Blimp
Diameter	203 ft (62 m)
Length	515 ft (157 m)
Width	approx. 300 ft (91 m)
Power	Solar and fuel cells

Each blimp will be equipped with a telecommunications payload to provide wireless broadband connections. The blimps will be able to carrying payloads of up to about 2,200 pounds (1,000 kg). Sky Station believes it can have its first blimp deployed by 2002. Each blimp will have a life span of about five to 10 years. Sky Station says that its user terminals will enable broadband connections of between 2 and 10 megabits per second (Mbps). Click here to see how the Sky Station system works.


Not to be left out of the high-flying Internet industry, NASA is also playing a role in a potential airborne Internet system being developed by AeroVironment. NASA and AeroVironment are working on a solar-powered, lightweight plane that could fly over a city for six months or more, at 60,000 feet, without landing. AeroVironment plans to use these unmanned planes as the carrier to provide broadband Internet access.

Photo courtesy NASA The Helios aircraft will be equipped with telecommunications equipment and stay airborne for six months straight.

Helios is currently in the prototype stage, and there is still a lot of testing to be done to achieve the endurance levels needed for AeroVironment's telecommunications system. AeroVironment plans to launch its system within three years of receiving funding for the project. When it does, a single Helios airplane flying at 60,000 feet will cover a service area approximately 40 miles in diameter.

Helios Aircraft
Weight	2,048 pounds (929 kg)
Wingspan	247 ft (75.3 m)
Length	12 ft (3.7 m)
Wing Area	1,976 square ft (183.6 m2)
Propulsion	14 brushless, 2-horsepower, direct-current electric motors
Range	1 to 3 hours in prototype tests 6 months when fully operational
Speed	19 to 25 mph (30.6 to 40.2 kph)

The Helios prototype is constructed out of materials such as carbon fiber, graphite epoxy, Kevlar and Styrofoam, covered with a thin, transparent skin. The main pole supporting the wing is made out of carbon fiber, and is thicker on the top than on the bottom in order to absorb the constant bending during flight. The wing's ribs are made of epoxy and carbon fiber. Styrofoam comprises the wing's front edge, and a clear, plastic film is wrapped around the entire wing body.
The all-wing plane is divided into six sections, each 41 ft (12.5 m) long. A pod carrying the landing gear is attached under the wing portion of each section. These pods also house the batteries, flight-control computers and data instrumentation. Network hubs for AeroVironment's telecommunications system would likely be placed here as well.
It seems that airborne Internet could take off in the very near future. If and when those planes and blimps start circling to supplement our current modes of connection, downloading the massive files we've come to crave for entertainment or depend on for business purposes will be a snap -- even if we live somewhere in that "last mile."