Chapter 9

Setting Up a Wireless Network

In This Chapter

Understanding wireless network standards

Reviewing basic radio terms

Considering infrastructure and ad-hoc networks

Working with a wireless access point

Configuring Windows for wireless networking

Since the beginning of Ethernet networking, cable has been getting smaller and easier to work with. The original Ethernet cable was about as thick as your thumb, weighed a ton, and was difficult to bend around tight corners. Then came coaxial cable, which was lighter and easier to work with. Coaxial cable was supplanted by unshielded twisted-pair (UTP) cable, which is the cable used for most networks today.

Although cable through the years has become smaller, cheaper, and easier to work with, it is still cable. So you have to drill holes in walls, pull cable through ceilings, and get insulation in your hair to wire your entire home or office.

The alternative to networking with cables is, of course, networking without cables . . . also known as wireless networking. Wireless networks use radio waves to send and receive network signals. As a result, a computer can connect to a wireless network at any location in your home or office.

Wireless networks are especially useful for notebook computers. After all, the main benefit of a notebook computer is that you can carry it around with you wherever you go. At work, you can use your notebook computer at your desk, in the conference room, in the break room, or even out in the parking lot. At home, you can use it in the bedroom, kitchen, den, or game room, or out by the pool. With wireless networking, your notebook computer can be connected to the network no matter where you take it.

Wireless networks have also become extremely useful for other types of mobile devices, such as smartphones and tablet computers. Sure, these devices can connect via a cell network, but that can get real pricey real quick. With a wireless network, though, you can connect your smart phone or tablet without having to pay your cellphone company for the connection time.

This chapter introduces you to the ins and outs of setting up a wireless network. I tell you what you need to know about wireless networking standards, how to plan your wireless network, and how to install and configure wireless network components. And if you end up with a hybrid network of wired and wireless, I show you how to create that, too.

Diving into Wireless Networking

As I mention earlier, a wireless network is just a network that uses radio signals rather than direct cable connections to exchange information. Simple as that. A computer with a wireless network connection is like a cellphone. Just as you don’t have to be connected (tethered) to a phone line to use a cellphone, you don’t have to be connected to a network cable to use a wireless networked computer.

Here are the key concepts and terms you need to understand to set up and use a basic wireless network:

WLAN: A wireless network is often referred to as a wireless local area network (WLAN). Some people prefer to switch the acronym around to local area wireless network, or LAWN.

Wi-Fi: The term Wi-Fi is often used to describe wireless networks although it technically refers to just one form of wireless network: the 802.11b standard. (See the section “Eight-Oh-Two-Dot-Eleventy Something?: Understanding Wireless Standards,” later in this chapter for more information.)

SSID: A wireless network has a name, known as a SSID. SSID stands for service set identifier. (Wouldn’t that make a great Jeopardy! question? I’ll take obscure four-letter acronyms for $400, please!) All the computers that belong to a single wireless network must have the same SSID.

Channels: Wireless networks can transmit over any of several channels. For computers to talk to one another, though, they must be configured to transmit on the same channel.

Ad-hoc: The simplest type of wireless network consists of two or more computers with wireless network adapters. This type of network is an ad-hoc mode network.

Infrastructure mode: A more complex type of network is an infrastructure mode network. All this really means is that a group of wireless computers can be connected not only to one another, but also to an existing cabled network via a device called a wireless access point (WAP). (I tell you more about ad-hoc and infrastructure networks later in this chapter.)

A Little High School Electronics

I was a real nerd in high school: I took three years of electronics. The electronics class at my school was right next door to the auto shop. All the cool kids took auto shop, of course, and only nerds like me took electronics. We hung in there, though, and learned all about capacitors and diodes while the cool kids were learning how to raise their cars and install 2-gigawatt stereo systems.

It turns out that a little of that high school electronics information proves useful when it comes to wireless networking — not much, but a little. You’ll understand wireless networking much better if you know the meanings of some basic radio terms.

Waves and frequencies

For starters, radio consists of electromagnetic waves sent through the atmosphere. You can’t see or hear them, but radio receivers can pick them up and convert them to sounds, images, or — in the case of wireless networks — data. Radio waves are actually cyclical waves of electronic energy that repeat at a particular rate: the frequency.

Figure 9-1 shows two frequencies of radio waves. The first is one cycle per second; the second is two cycles per second. (Real radio doesn’t operate at that low a frequency, but I figured that one and two cycles per second would be easier to draw than 680,000 and 2.4 million cycles per second.)

The measure of a frequency is cycles per second, which indicates how many complete cycles the wave makes in 1 second (duh). In honor of Heinrich Hertz — who didn’t invent catsup, but was the first person to successfully send and receive radio waves (it happened in the 1880s) — cycles per second is usually referred to as Hertz, abbreviated Hz. Thus, 1 Hz is one cycle per second.

Incidentally, when the prefix K (for kilo, or 1,000), M (for mega, 1 million), or G (for giga, 1 billion) is added to the front of Hz, the H is still capitalized. Thus, 2.4 MHz is correct (not 2.4 Mhz).

So the beauty of radio frequencies is that transmitters can be tuned to broadcast radio waves at a precise frequency. Likewise, receivers can be tuned to receive radio waves at a precise frequency, ignoring waves at other frequencies. That’s why you can tune the radio in your car to listen to dozens of radio stations: Each station broadcasts at its own frequency.

Figure 9-1: Radio waves frequently have frequency.

Wavelength and antennas

A term related to frequency is wavelength. Radio waves travel at the speed of light, and wavelength refers to how far the radio signal travels with each cycle. Because the speed of light is roughly 182,282 miles per second, for example, the wavelength of a 1 Hz radio wave is about 182,282 miles. The wavelength of a 2 Hz signal is about half that: a mere 91,141 miles.

As you can see, the wavelength decreases as the frequency increases. The wavelength of a typical AM radio station broadcasting at 580 KHz is about 522 yards. For a TV station broadcasting at 100 MHz, it’s about 3 yards. For a wireless network broadcasting at 2.4 GHz, the wavelength is just shorter than 5 inches.

And the shorter the wavelength, the smaller the antenna needs to be to adequately receive the signal. As a result, higher-frequency transmissions need smaller antennas. You may have noticed that AM radio stations usually have huge antennas mounted on top of tall towers, but cellphone transmitters are much smaller, and their towers aren’t nearly as tall because cellphones operate on a higher frequency than AM radio stations do. So who decides what type of radio gets to use specific frequencies? That’s where spectrums and the FCC come in.

Spectrums and the FCC

Spectrum refers to a continuous range of frequencies on which radio can operate. In the United States, the Federal Communications Commission (FCC) regulates not only how much of Janet Jackson can be shown at the Super Bowl, but also how various portions of the radio spectrum can be used. Essentially, the FCC has divided the radio spectrum into dozens of small ranges — bands — and restricted certain uses to certain bands. AM radio, for example, operates in the band from 535 KHz to 1,700 KHz.

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Table 9-1 lists some of the most popular bands. Note that some of these bands are wide — UHF television begins at 470 MHz and ends at 806 MHz — but other bands are restricted to a specific frequency. The difference between the lowest and highest frequency within a band is the bandwidth.

Table 9-1 Popular Bands of the Radio Spectrum

Band	Use
535 KHz–1,700 KHz	AM radio
5.9 MHz–26.1 MHz	Shortwave radio
26.96 MHz–27.41 MHz	Citizens Band (CB) radio
54 MHz–88 MHz	Television (VHF channels 2–6)
88 MHz–108 MHz	FM radio
174 MHz–220 MHz	Television (VHF channels 7–13)
470 MHz–806 MHz	Television (UHF channels)
806 MHz–890 MHz	Cellular networks
900 MHz	Cordless phones
1850 MHz–1990 MHz	PCS cellular
2.4 GHz–2.4835 GHz	Cordless phones and wireless networks (802.11b and 802.11n)
4 GHz–5 GHz	Large-dish satellite TV
5 GHz	Wireless networks (802.11a)
11.7 GHz–12.7 GHz	Small-dish satellite TV

Two of the bands in the spectrum are allocated for use by wireless networks: 2.4 GHz and 5 GHz. Note that these bands aren’t devoted exclusively to wireless networks. In particular, the 2.4 GHz band shares its space with cordless phones. As a result, cordless phones sometimes interfere with wireless networks.

Eight-Oh-Two-Dot-Eleventy Something?: Understanding Wireless Standards

The most popular standards for wireless networks are the IEEE 802.11 standards. These standards are essential wireless Ethernet standards and use many of the same networking techniques that the cabled Ethernet standards (in other words, 802.3) use. Most notably, 802.11 networks use the same CSMA/CD technique as cabled Ethernet to recover from network collisions.

The 802.11 standards address the bottom two layers of the IEEE seven-layer model: the Physical layer and the Media Access Control (MAC) layer. Note that TCP/IP protocols apply to higher layers of the model. As a result, TCP/IP runs just fine on 802.11 networks.

The original 802.11 standard was adopted in 1997. Two additions to the standard, 802.11a and 802.11b, were adopted in 1999. The latest and greatest versions are 802.11g and 802.11n.

Table 9-2 summarizes the basic characteristics of the four variants of 802.11.

Currently, most wireless networks are based on the 802.11n standard.

Home on the Range

The maximum range of an 802.11g wireless device indoors is about 300 feet. This can have an interesting effect when you get a bunch of wireless computers together such that some of them are in range of one another but others are not. Suppose that Wally, Ward, and the Beaver all have wireless notebooks. Wally’s computer is 200 feet away from Ward’s computer, and Ward’s computer is 200 feet away from Beaver’s in the opposite direction (see Figure 9-2). In this case, Ward can access both Wally’s and Beaver’s computers, but Wally can access only Ward’s computer, and Beaver can access only Ward’s computer. In other words, Wally and Beaver won’t be able to access each other’s computers because they’re outside the 300-feet range limit. (This is starting to sound suspiciously like an algebra problem. Now suppose that Wally starts walking toward Ward at 2 miles per hour, and Beaver starts running toward Ward at 4 miles per hour. . . .)

Note: Although the normal range for 802.11g is 300 feet, the range may be less in actual practice. Obstacles — solid walls, bad weather, cordless phones, microwave ovens, backyard nuclear reactors, and so on — can all conspire to reduce the effective range of a wireless adapter. If you’re having trouble connecting to the network, sometimes just adjusting the antenna helps.

Figure 9-2: Ward, Wally, and the Beaver playing with their wireless network.

Also, wireless networks tend to slow down when the distance increases. 802.11g network devices claim to operate at 54 Mbps, but they usually achieve that speed only at ranges of 100 feet or less. At 300 feet, they often slow to a crawl. You should also realize that when you’re at the edge of the wireless device’s range, you’re more likely to lose your connection suddenly due to bad weather.

Using Wireless Network Adapters

Each computer that will connect to your wireless network needs a wireless network adapter, which is similar to the network interface card (NIC) used for a standard Ethernet connection. Instead of having a cable connector on the back, however, a wireless network adapter has an antenna.

Just about all notebook computers come with wireless networking built in, so you don’t have to add a separate wireless network adapter to a notebook computer. Desktop computers, though, are a different story. They typically don’t have built-in wireless networking, so you’ll probably need to purchase one of two types of wireless adapters:

A wireless PCI card: You install this wireless network adapter in an available slot inside your desktop computer. Yup, you need to take your computer apart, so use this type of card only if you have the expertise and the nerves to dig into your computer’s guts.

A wireless USB adapter: This gizmo is a separate box that plugs into a USB port on your computer. Because you can install this type of adapter without taking your computer apart, USB adapters are more readily available than PCI card adapters. Yea!

Setting Wireless Access Points

Unlike cabled networks, wireless networks don’t need a hub or switch. If all you want to do is network a group of wireless computers, you just purchase a wireless adapter for each computer, put them all within 300 feet of one another, and voilà! — instant network.

But what if you already have an existing cabled network? Suppose that you work at an office with 15 computers all cabled up nicely, and you just want to add a couple of wireless notebook computers to the network. Or suppose that you have two computers in your den connected with network cable, but you want to link up a computer in your bedroom without pulling cable through the attic.

That’s where a wireless access point (WAP) comes in. A WAP actually performs two functions:

It acts as a central connection point for all your computers that have wireless network adapters. In effect, the WAP performs essentially the same function that a hub or switch performs for a wired network.

It links your wireless network to your existing wired network so that your wired computer and your wireless computers get along like one big happy family. This sounds like the makings of a Dr. Seuss story. (“Now the wireless sneeches had hubs without wires. But the twisted-pair sneeches had cables to thires. . . .”)

Wireless access points are sometimes just called access points (APs), which is basically a box with an antenna (or often a pair of antennae) and an RJ-45 Ethernet port. You plug the AP into a network cable and then plug the other end of the cable into a hub or switch, and your wireless network should be able to connect to your cabled network.

Figure 9-3 shows how an access point acts as a central connection point for wireless computers and also how it bridges your wireless network to your wired network.

Figure 9-3: A wireless access point connects a wireless network to a cabled network.

Infrastructure mode

When you set up a wireless network with an AP, you’re creating an infrastructure mode network: The AP provides a permanent infrastructure for the network. The APs are installed at fixed physical locations, so the network has relatively stable boundaries. Whenever a mobile computer wanders into the range of one of the APs, it has come into the sphere of the network and can connect.

An AP and all the wireless computers that are connected to it are a Basic Service Set (BSS). Each BSS is identified by a SSID. When you configure an AP, you specify the SSID that you want to use. The SSID is often a generic name — such as wireless — or it can be a name that you create. Some access points use the MAC address of the WAP as the SSID.

Multifunction WAPs

Wireless access points often include other built-in features. Some APs double as Ethernet hubs or switches; in that case, the AP will have more than one RJ-45 port. In addition, some APs include broadband cable or DSL firewall routers that enable you to connect to the Internet. For example, I use a Linksys wireless router in my home. It includes the following features:

A wireless access point that lets me connect a notebook computer and a computer located on the other side of the house

I didn’t want to run cable through the attic.

A four-port gigabit switch that I can use to connect up to four computers via twisted-pair cable

A DSL/cable router that I connect to my cable modem

This router enables all the computers on the network (cabled and wireless) to access the Internet.

A multifunction AP designed to serve as an Internet gateway for home networks is sometimes called a residential gateway.

Roaming Capabilities

You can use two or more WAPs to create a large wireless network in which computer users can roam from area to area and still be connected to the wireless network. As the user moves out of the range of one AP, another AP automatically picks up the user and takes over without interrupting the user’s network service.

To set up two or more APs for roaming, you must carefully place the WAPs so that all areas of the office or building that are being networked are in range of at least one of the WAPs. Then just make sure that all the computers and APs use the same SSID.

Two or more APs joined for roaming, along with all the wireless computers connected to any of the access points, form an Extended Service Set (ESS). The access points in the ESS are usually connected to a wired network.

One of the current limitations of roaming is that each AP in an ESS must be on the same TCP/IP subnet. That way, a computer that roams from one AP to another within the ESS retains the same IP address. If the APs had a different subnet, a roaming computer would have to change IP addresses when it moved from one AP to another.

Wireless bridging

Another use for wireless APs is to bridge separate subnets that can’t easily be connected by cable. Suppose that you have two office buildings that are only about 50 feet apart. To run cable from one building to the other, you’d have to bury conduit — a potentially expensive job. Because the buildings are so close, though, you can probably connect them with a pair of WAPs that function as a wireless bridge between the two networks. Connect one of the APs to the first network and the other AP to the second network. Then configure both APs to use the same SSID and channel.

Ad-hoc networks

A WAP isn’t necessary to set up a wireless network. Any time two or more wireless devices come within range of each other, they can link up to form an ad-hoc network. If you and a few of your friends all have notebook computers with wireless adapters, for example, you can meet anywhere and form an ad-hoc network.

All the computers within range of one another in an ad-hoc network are an Independent Basic Service Set (IBSS).

Configuring a Wireless Access Point

The physical setup for a WAP is pretty simple: You take it out of the box, put it on a shelf or on top of a bookcase near a network jack and a power outlet, plug in the power cable, and plug in the network cable.

The software configuration for an AP is a little more involved but still not very complicated. It’s usually done via a web interface. To get to the configuration page for the AP, you need to know its IP address. Then you just type that address in the address bar of a browser on any computer on the network.

Multifunction APs usually provide DHCP and NAT services for the networks and double as the network's gateway router. As a result, they typically have a private IP address that's at the beginning of one of the Internet's private IP address ranges, such as 192.168.0.1 or. Consult the documentation that came with the AP to find out more.

If you use a multifunction AP that serves as both your wireless AP and your Internet router, and you can't remember the IP address, run the IPCONFIG command at a command prompt on any computer on the network. The Default Gateway IP address should be the IP address of the access point.

Basic configuration options

Figure 9-4 shows the main configuration screen for a typical router. I called up this configuration page by entering 192.168.1.1 in the address bar of a web browser and then supplying the login password when prompted.

Figure 9-4: The main configuration page for a Linksys wireless router.

On the main setup page of this router, you configure information such as the hostname and IP address of the router and whether the router’s DHCP server should be enabled. Options found on additional tabs allow you to configure wireless settings, such as the network name (SSID), the type of security to enforce, and a variety of other settings.

DHCP configuration

You can configure most multifunction APs to operate as a DHCP server. For small networks, the AP is commonly the DHCP server for the entire network. In that case, you need to configure the AP’s DHCP server. Figure 9-5 shows the DHCP configuration page for a Linksys WAP router. To enable DHCP, you select the Enable option and then specify the other configuration options to use for the DHCP server.

Larger networks with more demanding DHCP requirements are likely to have a separate DHCP server running on another computer. In that case, you can defer to the existing server by disabling the DHCP server in the AP.

For more information on configuring a DHCP server, please refer to Chapter 5.

Figure 9-5: Configuring DHCP for a Linksys wireless router.

Connecting to a Wireless Network with Windows Vista, 7, or 8

When Windows Vista, 7, or 8 detects that a wireless network is within range, a balloon notification appears onscreen to indicate that one or more wireless networks are available. Click this balloon to summon the dialog box shown in Figure 9-6 and then choose the network you want to connect to.

Figure 9-6: Choosing a wireless network.

Configuring Windows XP for Wireless Networking

If you need to configure an older Windows XP computer for wireless networking, you must first install the appropriate device driver for your wireless network adapter. To do that, you need the installation CD that came with the adapter. Follow the instructions that came with the adapter to install the drivers.

Windows XP has some nice built-in features for working with wireless networks. Follow these steps to access the features:

1. Open the Network Connections folder.

Choose Start⇒Control Panel and then double-click the Network Connections icon.

2. Right-click the wireless network connection and choose Properties to open the Properties dialog box.

3. Click the Wireless Networks tab (see Figure 9-7).

Figure 9-7: Configuring wireless networking in Windows XP.

Each time you connect to a wireless network, Windows XP adds that network to this dialog box. Then you can juggle the order of the networks in the Preferred Networks section to indicate which network you prefer to join if you find yourself within range of two or more networks at the same time. You can use the Move Up and Move Down buttons next to the Preferred Networks list to change your preferences.

To add a network that you haven’t yet joined, click the Add button. This action opens the dialog box shown in Figure 9-8. Here, you can type the SSID value for the network that you want to add. You can also specify other information, such as whether to use data encryption, how to authenticate yourself, and whether the network is an ad hoc rather than an infrastructure network.

Figure 9-8: Adding a wireless network in Windows XP.

When your computer comes within range of a wireless network, a pop-up balloon appears on the taskbar, indicating that a network is available. If one of your preferred networks is within range, clicking the balloon automatically connects you to that network. If Windows XP doesn’t recognize any of the networks, clicking the balloon displays the Wireless Network Connection dialog box. From there, you can choose the network that you want to join (if more than one network is listed) and then click Connect to join the selected network.