The FAQs about WLANs
Published: 22 Nov 2002 20:44 GMT
What do I need for wireless networking?
You'll need an interface card per connected PC, and if you want to work with a wired network or broadband you'll have to have an access point as well -- also called a wireless gateway. Your access point can be a PC with gateway software, a wireless connection and a LAN or WAN connection, or you can get stand-alone routers with wireless. Cards are either PC Card format, Compact Flash, mini-PCI or USB: desktop PCs use PC Card adaptors with PCI or ISA adapters. All cards and access points come with their own antenna and any necessary power supply.
What are the different sorts of wireless networking?
Most wireless networks run under the umbrella term of 802.11, which also refers to an old 2Mbps standard. By far the most common variant is 802.11b, which is 11 Mbps; you'll also come across 802.11a, which is 55Mbps on a different frequency, and 802.11g, which is 55Mbps on the same frequency as 802.11b -- but that won't be approved until the second quarter of next year. Wi-Fi is a marketing term for 802.11b and 802.11a, although the two standards don't talk to each other.
You can also use Bluetooth for small-scale networking. You may come across Zigbee, WirelessUSB and MDMA/Nanotron -- at the time of writing these are expected to start to appear in 2003 and no practical advice can be given except to regard them with baleful suspicion.
What is the maximum range of a wireless network?
For most systems out of the box, you should expect around 50-100 metres range across open space, but considerably less within buildings. For more range, site the access point or base station as high as possible and as clear of obstructions as you can: the radio signals can go through walls, floors and so on but are severely attenuated. If you replace the standard antennae with high gain, directional antennae you can extend the range of a network to kilometres, but only point-to-point. The world record stands at 72 miles.
What speed should I expect from a wireless network?
In general, maximum throughput is around half of the rated speed, so an 802.11b link will manage around 5 to 6, exceptionally 7, Mbps. Some manufacturers are introducing their own "turbo" variants to the standards to get higher speeds, typically 22Mbps nominal, 7 or 8 actual, but this is a very fluid area. Often, these upgrades are free and just need a flash upgrade to your access point and interface cards, but there can be compatibility issues.
Also, the further your network cards are apart, the slower the connection. Making small changes to location can make big differences in throughput.
Can I make a wireless network secure?
You can secure a wireless network against casual access by enabling standard security settings. WEP should be enabled at the highest setting -- it's not perfect, but it's worth having -- and you should change your network's Service Set Identifier (SSID) to something unguessable. Disable Broadcast SSID. Put your wireless access point in the middle of the building, to minimise leakage outside. If your wireless access point allows it, restrict connections to registered wireless interface cards through their MAC addresses. Taking the above steps won't make your network invulnerable, but it will secure it against passing trade or the bloke next door.
Do different kinds of wireless networking interfere with each other?
Most of the wireless networks in use today share the 2.4GHz radio band, and can interfere with each other. However, those that have a high likelihood of being used at the same time and the same place -- Bluetooth and 802.11b, for example -- have been tested together and standards evolved to minimise interference. Other devices -- microwave ovens, wireless cameras, videosenders -- can also cause interference with wireless networking, and should be suspected if you have continued and otherwise inexplicable connection loss or low speeds.
How about ultrawideband? Will that make my wireless network obsolete?
Perhaps -- in around ten years' time. UWB is still very new and the first uses will probably be for very short range, very high speed data such as high resolution video. Given the very high level of use of 802.11b, its moderate cost and high reliability, it is unlikely to be usurped as the leading standard for at least two years, after which dual- or triple-standard chipsets including 802.11b, 802.11a and 802.11g will probably take over. Given the modest cost, any investment today in 802.11b will more than live up to expectations.
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