SolveYourProblem
eLearning Series
Wireless Networking
Wireless
Network Cards:
Range, Speed and Standards
by Jeff Cohen
Not sure what
you're doing in your wireless card shopping? Want to make
sure you're buying the right thing but just have no idea
what it is you're looking for? Well, you've come to the right
place. When you're looking to buy a wireless network
card, I can tell you right now that you're looking
at three key issues: range, speed, and standards.
A Typical
Specification
This is a specification
for a Linksys wireless PCMCIA laptop card I
just bought:
11 Mbps high-speed
transfer rate; interoperable with IEEE 802.11b (DSSS) 2.4Ghz-compliant
equipment; plug-and-play operation provides easy set up;
long operating range (up to 120m indoor); advanced power
management features conserve valuable notebook PC battery
life; rugged metal design with integrated antenna; compatible
with virtually all major operating systems; works with all
standard Internet applications; automatic load balancing
and scale back; model no. WPC11. (source: amazon.com).
Now, some of those
things can be pretty much ignored. Really, 'virtually all
major operating systems'? That means nothing. The reason
I've put it here, though, is so you can see which things
are important to keep an eye out for.
Range
See where it says
'up to 120m indoor'? This tells you that the maximum range
of the wireless card you're looking at is 120 metres. That's
what it would be if everything was perfect. In practice,
thick walls and interference can reduce this number by as
much as 90%.
Without enough
range, your wireless network is going to be pretty useless.
It's not much fun having no wires when you have to keep all
the computers in the same room to get them to connect to
each other.
As a rule of thumb,
unless your walls are made of drywall or wood, it's best
to buy about four times the strength you'd think you'd need.
Even in perfect conditions, get twice as much, to be safe.
If you need to convert from metric to imperial units, remember
that there are 30 centimetres (0.3 metres) in a foot and
about 2.5 centimetres in an inch - you shouldn't have too
much trouble.
Speed
Do you see where
it says 'Mbps' in that description? That number is the speed
of the wireless connection. 11 Mbps is about one and a half
megabytes per second - to convert megabits (Mb) to megabytes
(MB), just divide by eight. 802.11b wireless cards all have
a speed of 11Mbps, while 802.11g ones run at 54Mbps - the
next generation will be even faster.
Speed is important
to your wireless network because it's going to directly influence
how long you have to wait for things like files to transfer
from one computer on the network to the other. It is less
important for Internet use, however, because there are currently
very few Internet connections running at speeds over 11Mbps
- it's really as much as you need, at least for now.
Standards
Somewhere in the
specification of what you're looking at, you should see the
number '802.11', followed by a letter 'a', 'b' or 'g'. This
is the standard that the wireless device conforms to, and
tells you whether you will be able to use it with your other
wireless devices.
Basically, 802.11b
and 802.11g are compatible with each other. 802.11a is not
compatible with either and is quite a bad standard all round,
so you shouldn't buy 802.11a. Out of b and g, b is cheaper
but slower, while g is more expensive but faster. It's worth
considering that adding a b-speed device to a network that
has g-speed devices will often slow the whole network down
to b-speed, making the g-devices pointless.
If your wireless
device doesn't conform to the right standards, it's not going
to be much good to you. I often see naive people bidding
for used wireless equipment on eBay, not realizing that it's
going to be terribly slow and not work with any other equipment
they might have. Always make sure that you check what standard
the wireless equipment is - if you don't know the 802.11
letter, don't buy it!
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SolveYourProblem.com : 2007
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