The lay of the LAN

Brian Nadel ZDNet US

Published: 06 Feb 2003

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Because physical structures can eat up wireless signals, the layout of your home or office -- the placement of walls, hallways and doors -- counts for everything. If you ignore the floor plan, you may end up with a network that fails to reach every nook and cranny.

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. 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 and stone are the worst wall materials (the signal barely trickles through), while 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 reception.

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 kit.

Wireless networking equipment
	Pros	Cons	Approximate cost: 802.11b / a
Router/gateway	combines Ethernet router and access point in one small box	devices can't be mixed and matched to get best of breed	£100 / n/a
Access point	powerful central radio for setting up wireless LAN	expensive; involved setup; sometimes hard to optimise location	£100 / £150
PC Card	small, power-efficient radio for notebooks	puts extra power drain on battery-operated equipment; takes up a PC Card slot	£50 / £75
CompactFlash card	very small; for use in handhelds and cellphones	limited range; expensive; drains battery	£60 / n/a
USB adapter	desktop or notebook device that connects via USB port; signal can be optimised with a boom antenna	bandwidth often too low for high-speed LANs	£50 / n/a
Buetooth	connects to desktop PC via internal card slot, but radio is stuck behind the computer	PC must be opened to install; some products require a PC Card to operate	£50 / £100

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, while newer notebooks such as the Dell Inspiron 8200 these features as standard equipment. Integrated 802.11a radios are just beginning to become 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 organisation's process for testing 802.11a devices is only just getting started.

Once all your devices are wireless ready, they need a basic access-point (AP) radio to communicate. Check here for reviews of the latest APs. 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 minimise 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. At less than £150, Wi-Fi devices can be an inexpensive, one-stop distribution centre for your wireless LAN. Good choices include:

ZoomAir Internet Gateway IG-4165

D-Link AirPlus DI-614+

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