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WiFi – Wireless networking explained

by James Morris on 15 August 2005, 00:00

Quick Link: HEXUS.net/qabnw

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Home networking lets you do great things that aren't possible with standalone PCs. Printers can be shared between PC, so there's no need to buy one for each machine; data can be swapped around virtually instantaneous; and every PC can go on the net via a single modem or ADSL connection. But, for many years, the price to be paid was having messy wires trailing all around the house, with associated hazards such as disentangling the dog from the mess or persuading the cat to stop chewing cables. Then along came the WiFi wireless networking standard, allowing computers and peripherals to communicate without all those cables.

How it works

WiFi stands for Wireless Fidelity and is a trademark of The Wi-Fi Alliance – a not-for-profit organisation set up to certify and promote wireless kit conforming to the IEEE 802.11 standard. Knock off the IEEE and you're left with 802.11 - the other name used for WiFi. Whatever you call it, the driving principle is supposed to be simplicity. Users should be able to easily connect to one another via radio frequencies at ranges of 30m or more.

Currently, there are three basic variants of 802.11:

  • 802.11b was the first mass-marketed standard. It operates at a frequency of 2.4GHz and, with a nominal maximum data rate (never achieved) of 11Mbit/sec, is slow compared to the standards that followed.
  • 802.11a came next. This operates at 5GHz and theoretically offers a data transfer speed of 54Mbit/sec.
  • 802.11g is the standard that most users have bought into over the last year or so. Like 802.11b, it operates at 2.4GHz and is not much more expensive yet offers the same theoretical speed as 802.11a – 54Mbit/sec.

The underlying principle of WiFi is that computers communicate with one another over a radio frequency in much the same way that handheld transceiver are used by friends to chat with one another on the road. One key difference, though, is the bandwidths each uses.

Handhelds transmits on a frequency of around 50MHz but 802.11b and 802.11g devices transmit on the 2.4GHz band and 802.11a use 5GHz. These higher frequencies provide much greater bandwidth for information to be transferred.

802.11b devices can also transmit on several smaller bands within their allotted spectrum and can hop rapidly between them. This helps prevent interference and allows multiple WiFi devices to communicate without causing problems with each other.

And that's important because WiFi isn't intended to serve just a few users at home or in an office – it's also supposed to handle large numbers of users and be suitable for laptops that get out and about. Many modern portable PCs have onboard WiFi hardware as standard, but those that don't can be kitted out quite cheaply with a CardBus or USB-dongle solution.

But if you've got the kit and are raring to communicate without the constraint of wires, what else do you need? First thing is a “hotspot”. At home that would usually be provided by a wireless-enabled modem/router but more and more public places are being fitted out for WiFi.