Ever wanted to connect computers without cables? Our primer will explain the different wireless technologies, help you get started, and offer tips on making your wireless network secure and efficient.

Wireless networking may save you from the physical hassle of connecting computer hardware, but you still have to face the virtual tangle of standards, as well as a knot of installation and security considerations. This four-part primer will explain the different wireless technologies, help you get started, and offer tips on making your wireless network secure and efficient.

The basics of wireless networking
Confused by the alphabet soup of wireless-networking technologies? We'll tell you what you need to know.

The lay of the LAN
Before you jump into wireless, make sure you pick the right equipment for the job.

Sweating the details
No matter which networking standard you choose, installing it involves some basic rules and processes; we'll walk you through them.

Optimizing and securing your network
If you build it, they will come. A wireless network can attract all sorts of undesirables. We'll show you how to keep them out.

The basics of wireless networking

Currently there are three wireless-networking standards competing for your airtime. Wi-Fi (802.11b) is the corporate darling and has a suitably wide range for use in big office spaces. 802.11a offers bigger bandwidth and fewer interference problems but a shorter range. Bluetooth is meant for short-range, temporary networking in conference rooms, schools, or homes. In addition to the detailed rundowns below, check out our side-by-side comparison of these different technologies with traditional, wired Ethernet.

*For 100Mbps network

Wi-Fi reigns supreme
Wi-Fi is currently the most popular and least expensive wireless LAN specification. It operates in the 2.4GHz radio spectrum and can transmit data at speeds up to 11Mbps within a 100-foot range. Its balance of economy, bandwidth, and particularly range have made it the dominant standard for business, and many employees have taken the technology home with them for work and family computing. The Wireless Ethernet Compatibility Alliance (WECA) has done its part by certifying hundreds of products to make sure they work together. But Wi-Fi has a couple of drawbacks. It shares airspace with cell phones, Bluetooth, security radios, and other devices, so it's vulnerable to interference. And because of data-transfer overhead and the inevitable wall or other transmission obstacle, its real throughput is closer to 5Mbps, or about half of its spec.

802.11a: new kid on the block
A recent arrival, 802.11a has a couple of advantages over Wi-Fi. It runs at a less-populated frequency (5.15GHz to 5.35GHz) and, thus, is less prone to interference. Its bandwidth is much higher, at a theoretical peak of 54Mbps. Even though actual throughput is closer to 22Mbps, it still offers a lot more elbowroom than Wi-Fi does for transferring high-quality digital audio and video or other large files across the network, as well as for sharing a broadband connection. And some manufacturers offer proprietary modes that can push throughput a little higher. Its main problem is its shorter range: 50 feet compared to Wi-Fi's 100, forcing you to buy more access points to ensure full coverage. 802.11a equipment is also currently more expensive than its Wi-Fi counterparts, although the price gap is narrowing steadily. In November, WECA will start certifying 802.11a products, which will carry the organization's new Wi-Fi Certified capabilities label.

Because Wi-Fi and 802.11a use different radio technologies and portions of the spectrum, they are incompatible with one another. However, twin-standard equipment is currently available, which makes switching back and forth surprisingly simple. Still, if you want to make a choice between the two and stick to it, consider these factors: If you already use one or the other standard at your business, you should probably use the same one at home to make telecommuting easier. If compatibility and price are not issues, 802.11a's better performance could be worth the extra expense. But if you need to cover a lot of ground cheaply, Wi-Fi's the more efficient choice.

Bluetooth takes small bites, chews slowly
Named for a tenth-century Danish king, Bluetooth is a somewhat different standard from Wi-Fi or 802.11a, offering much more flexibility but on a smaller, "personal area network" scale. Its actual throughput is a poky 300Kbps, and its range is just a couple dozen feet. But unlike Wi-Fi and 802.11a, which require adapters, routers, gateways, access points, and synchronized setup schemes to connect devices, any devices with a Bluetooth radio and antennae can speak to each other with little or no preparation. It's also poised to replace infrared ports as the instant-transfer mode of choice, with better range and no line-of-sight requirement. Meeting attendees can immediately transfer files between their Bluetooth-equipped notebooks across a conference table, or they can send a file to a Bluetooth-equipped printer without downloading drivers. Bluetooth-equipped kiosks in airports and coffee houses let you log on to the Internet through your laptop or PDA. Bluetooth will soon be standard equipment on many cell phones and handheld computers. There's even talk of putting Bluetooth into home appliances. But for all the theoretical benefits of Bluetooth, the reality is that it's currently a mess of incompatible hardware and software. And because Bluetooth and Wi-Fi occupy the same frequency range, they can eat into each other's bandwidth and reduce throughput by 10 percent or more.

What lies ahead
This alphabet soup of standards will get even more complicated over the next few years, as upcoming standards come to market. For instance, 802.11g promises to increase Wi-Fi bandwidth to 22Mbps, while 802.11i will plug some of the security holes in the WEP protocol. A new Bluetooth specification will operate at a higher frequency, yielding twice its present bandwidth.

In the next section, we'll look at how to set up a wireless LAN, what equipment you'll need, and how much it will cost.

The lay of the LAN

Break out the blueprints
First, size up your location. We know Wi-Fi works best for large spaces and 802.11a for high-throughput applications, while Bluetooth simply requires devices to be in close proximity. Our sample office floor plan shows how you could use just one Wi-Fi access point, centrally located, to cover a 20,000-square-foot workspace. It could also cover a typical one- or two-story home and the outdoor property around it. A single 802.11a access point could cover a modest house or apartment. Remember, wireless networks range vertically as well as horizontally; depending on the building's construction, you may be able to cover as much as a floor above and below the access point or router. Still, various physical and technical obstacles may require you to place networking devices strategically or add extras to compensate for problems.

Every wall and ceiling is a potential barrier to radio signals of any kind. Plaster walls are the easiest to go through, although older construction (which includes wood, lathe, metal screens, and plaster) can eat up signals. Steel or stone is the worst wall material; the signal barely trickles through. Glass acts like a reflector, bouncing back the signal. The only solution is to place the access points to avoid walls and dead ends. Sometimes the best technique is trial and error--testing a device in a variety of locations for the best receptivity.

Choosing the right gear
In most environments, you'll need three different types of equipment. Check out our side-by- side comparison of the different types of equipment.

Every device you want to network will need a radio for exchanging communications wirelessly. If you have an older notebook, you can easily add a wireless PC Card adapter (such as the Orinoco or a USB radio), while newer notebooks such as the Dell Inspiron 8200 offer these features as standard equipment. (There are currently no integrated 802.11a radios available for notebooks.) Smaller CompactFlash cards such as the D-Link DCF-650W work well for handheld computers, but they're expensive and have limited range. For desktops, think USB or PCI adapters. The WECA logo assures Wi-Fi compatibility, but the organization's process for testing 802.11a devices is just getting started.

Once all your devices are wireless ready, they need a basic access-point (AP) radio to communicate. An AP can act as the wireless network's hub, letting multiple computers share a broadband connection, or it can be hooked up to a wired network to add wireless devices. If your network needs to span larger spaces, you can always add extra access points and place them in an overlapping pattern to minimize dead spots. You can connect the extra access points to your wired network or use them as bridges to relay the signal to other APs.

If you want to create a network combining both wired and wireless connections, a wireless gateway, which adds an Ethernet router, would be a good choice. Wi-Fi devices can be an inexpensive, one-stop distribution center for your wireless LAN.

Sweating the details

With your floor plan and equipment in hand, it's time to put it all together. After you've unpacked the gear and read through the documentation, you'll need a few extra supplies, including a tape measure and some Cat-5 network cables. From start to finish, setting up your wireless LAN should take less than an hour. Our sample scenario will involve setting up a wireless access point and several client PCs to share a broadband connection, but the same general advice applies to setting up wireless routers and gateways as well.

Location, location, location
First, perform a site survey of your home or office. Walk around the area you want to network to find the best location for your AP. Here are some general tips for choosing a good location:

•  The maximum distance you plan to travel from the AP should remain within the AP's specified range.
•  To cut down on interference, avoid areas with thick walls.
•  To keep the cabling as short as possible, you should place the AP close to your broadband connection.
•  Make sure you place the AP next to an outlet for electrical power.
•  Keep the AP reasonably well hidden and away from traffic, for both aesthetics and its own safety. Bookshelves, entertainment centers, and the tops of appliances, such as a refrigerator, can provide a flat, out-of-the-way location. As an alternative, many manufacturers include or sell mounting kits for attaching the AP to a wall. If you have removable acoustic tiles, you can even place the AP within the ceiling.
•  Place the AP up high to reduce obstacles or down low to help hide the power and connection cables.

Read the directions
With the AP's location settled, you can begin building your wireless LAN. Start by installing a wireless adapter in each notebook or desktop computer you want to network. Because the software and hardware can vary by vendor, we strongly recommend that you read the instructions carefully before you begin. Once each adapter is installed, open the user interface and enter the SSID or the name of your network.

Depending on the manufacturer, you may have to use Windows' wireless-networking software to configure the client. For Windows XP users, click Start>Settings>Network Connections>Wireless Network Connection. From there, click the Advanced button, and enter the particulars of your network. It's a good idea to record those settings, as you'll want them to be the same for all devices on the network.

To make installation easier, let DHCP automatically assign IP addresses to your networked computers and leave WEP security turned off. (Unfortunately, some manufacturers make you use an explicit IP address before you can access the AP; check the documentation for help.)

Try, try again
With the client taken care of, it's now time to configure the AP. Connect your cable or DSL modem to the AP using a Cat-5 cable. If your AP shipped without a cable, you can get one at your local electronics or computer store. Most devices include an integrated configuration tool that you access over a standard Web browser. Enter the AP's network details to match the client's, then reboot the AP.

Now take a minute to make sure the network works. The easiest way is to point your Web browser to a reliable page and see if it connects. If you get a warning that the page is unavailable, try again. Still having trouble? Here's a quick troubleshooting checklist:

•  Make sure all the network settings between the client and access point match, including SSID, DHCP, and encryption.
•  Check the sequence of status lights on the AP and refer to the system's documentation for possible errors.
•  Make sure you properly installed the AP's antennae and secured all cable connections.
•  Check the signal strength on the client end to make sure the AP is within range.
•  Clear your Web browser's cache and restart the AP or router.
•  Look for possible interference with other devices, such as security radios or Bluetooth connections.
•  As a last resort, reboot the AP to return it to its default settings, then start again.

With everything working, set the WEP encryption to the highest security level the client and access point can handle, likely 128- or 152-bit encryption, although some now go to 256-bit.

In the next installment, we'll go over more ways to secure and optimize your wireless network.

Optimizing and securing your network

Because wireless signals often travel beyond the physical confines of your home or office, you must take extra precautions to secure your network. Otherwise, any hacker on the street with a suitable radio can gain access to your network. In addition to the steps listed below, make sure you check and update your firewall software.

Keep out
The first line of defense is the SSID, which can be up to 32 characters in length. Make sure you change this to a unique network name right away. Leaving the factory-default setting in place-- typically wireless, any , or the manufacturer's name--is like leaving your house's front door open.

You guard your network's "back door" by setting the WEP encryption on the AP and the clients. While the AP can create and distribute a new WEP key for each session, the network still must broadcast the key through the air, which can compromise security. Manufacturers promise an update to the security protocol in the near future, but in the meantime, we suggest you enter a key manually on both the AP and the client. Unfortunately, this means you must enter 26 letters and numbers for a 128-bit key. You should also choose a random sequence of letters and numbers, then change it frequently.

What, me worry?
Still worried about security? You could set the EAP on the access point to authenticate only those clients with a smart card or other high-level security device--if you use one of the handful of notebooks that support them. Alternatively, you can use a proprietary security system to lock the network's windows as well as its doors. One of our favorites is Kerberos, which was developed at MIT and named for Greek mythology's three-headed guard dog at the gates of Hades. It works with all major operating systems except Mac; it sends out keys in encrypted form, so snoopers would have to work hard to break in.

You can also keep bad guys out by turning off DHCP. Instead, give an exact IP address or range of IP addresses for your computers. Theoretically, the hacker will be stuck on the outside of your network. You can also set the AP to allow only a predetermined list of MAC addresses to connect or to have full network access.

With so many different parameters to keep track of, we suggest you write them all down. If you're at home, put the AP's IP address, SSID, WEP level, and other details on a card, then tape it on the back of the AP or keep it with the documentation. Office users should keep all the network settings in a secure location.