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BOOT CAMP 455 (19/12/06)
Wireless Networking, part 1
The pace of development in Wi-Fi technology is
such that a Boot Camp how-to-do-it guide has become an annual event. That and
the fact that wireless networking is now the third most frequent topic in
reader’s emails and letters, after Spam and Windows foibles…
When we first looked at setting up a home
wireless network in 2003 it was still something of a black art. Back then
configuring a Wi-Fi adaptor and router took ages, required a fair amount of
technical savvy, not to mention the patience of a saint, the hardware was
eye-wateringly expensive and wireless ‘Hotspots’ were a rarity.
Nowadays it is a lot easier and much cheaper.
Nevertheless, there are still a few hurdles and pitfalls for the unwary (and
unlucky), but the good news is that for most PC users getting connected should
be a relatively quick and painless exercise.
For the benefit of newcomers and before we get
too involved with the nuts and bolts it is worth taking a brief tour around the
technology, to see what it does and how it works. I should also point out that
we are only going to be talking about wireless networking on Windows XP and
Vista PCs. There’s nothing to stop you hooking up earlier versions of Windows
(see Boot Camps 281 to 286), you can also mix and match wireless connections
with Windows, Mac and Linux PCs but we’ve got to draw the line somewhere,
otherwise this could go on forever…
Over the years there have been numerous
attempts to get computers to communicate with one another through a wireless
connection but it wasn’t until 1999, when a group of manufacturers got together
to form the Wireless Ethernet Compatibility Alliance (WECA later renamed the
Wi-Fi Alliance) that things started to get moving. Until that point there was a
lot of confusion over technical standards and compatibility. The Wi-Fi Alliance
settled a common standard, (IEEE 802.11); it also carries out testing and
certification and promote the technology as a brand, which we now know as
‘Wi-Fi’.
There are a number of Wi-Fi systems based on
the 802.11 standard and the first to be developed was 802.11a. It uses the 5GHz
frequency band, which makes equipment expensive to manufacture; take up was
slow and it is now virtually obsolete.
All current Wi-Fi systems operate on the 2.4GHz
frequency band, close to the one used by cordless telephones and microwave
ovens (which can cause interference problems). The first and still very popular
variant to go on general sale in 2002 was 802.11b and a year or so later it was
joined by 802.11g. This has now virtually taken over from 802.11a because it
provides much faster data transfer rates at almost no extra cost. Since the two
systems are very closely related most recent 802.11g devices are dual-standard
and are ‘backwards compatible’ with 802.11b devices.
Although 802.11b/g Wi-Fi is an international
standard there are differences in the number of channels, channel frequency
allocations and permitted power levels used in other countries so it is unwise
to purchase wireless equipment abroad.
For the record, on a good day, with the wind in
the right direction 802.11b data transfer rates are up to 11 megabits per
second (mbs). However 802.11g really gets your data moving at a blistering
54mbs. The range on both systems is from around 25 metres indoors to 100 metres
or more in the open. Specialist high power systems, ‘range extenders’,
high-gain antennas and so on are also available, which in some cases can boost
the range to several kilometres. There are several other 802.11 variants
waiting in the wings with even faster data transfer rates, better range and so
on but for the moment the Wi-Fi systems and devices you are most likely to
encounter use the 802.11b and 802.11g standards.
Most Wi-Fi hardware falls into three fairly
distinct categories: adaptors, routers and access points. Adaptors are
miniature ‘transceivers’ (transmitter-receivers) that are either built-in to a
PC (as is the case with many laptops nowadays) or in the form of a plug-in
module.
There are three common types of adaptor: USB,
card and PCI. USB adaptors are either small boxes with a USB connecting cable
or ‘dongles’ that plug directly into a PC’s USB socket. Card adaptors come in a
variety of formats, from credit card shaped PCMCIA or ‘PC-Cards’ to
postage-stamp sized MMC/SD and CF cards (the same format used for digital
camera memory cards) for use in pocket PCs and portable devices with wireless
capabilities. PCI Wi-Fi adaptors fit into expansion slots on desktop computer
motherboards.
Wi-Fi routers are the wireless network
equivalent of a telephone exchange. They act as a central hub, sharing an
Internet connection between several PCs and conveying data between the PCs
connected to the router by wireless link or Ethernet cable. Wireless routers
can also be combined with a broadband modem. These are normally stand-alone
devices, which means the Internet connection is always available, without
having to leave any PCs switched on.
Access Points are not very common in home
wireless set-ups and are mostly to be found in larger scale wired computer
networks, providing network access for Wi-Fi enabled devices.
Next Week -- Wireless Networking
JARGON FILTER
DONGLE
Originally
a type of electronic key (‘dangling’ on the end of short wire) used to unlock
some types of software or any small device that plugs into a PC
MMC/SD/CF
MultiMedia
Card, Secure Digital, Compact Flash -- types of memory modules used to store
and move data between digital cameras, MP3 players, portable PCs, cellphones
etc
PCMCIA
Personal
Computer Memory Card International Association. Body responsible for PC card
standards. Credit card sized modules (but a little thicker) used in laptops for
modems, memory expansion and other peripherals
TOP TIP
Is Wi-Fi bad for you? Almost inevitably it has been added to the
list of technologies that may be hazardous to your health but the evidence so
far is almost entirely anecdotal and no serious scientific study has linked
Wi-Fi with any sort of health concern.
Emissions from wireless adaptors and routers are a fraction of
those coming from mobile phones nor are they held in close proximity to the
user’s head or body, and since radio frequency energy follows the inverse
square law the amount of energy these devices produce at distances of more than
a few centimetres are vanishingly small. The odds are something else will get
you…
---end---
© R. Maybury 2006, 1312
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