Wireless Home Networking - Index of

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Part I: Wireless Networking Fundamentals
Gauging your network’s throughput
Wi-Fi standards call for different speeds, up to
11 Mbps for 802.11b and up to 54 Mbps for
802.11a and g — newer devices try to communicate
at up to 110 Mbps. Radios attempt to
communicate at the highest speed. If they
encounter too many errors (dropped bits), the
radio steps down to the next fastest speed and
repeats the process until a strong connection is
achieved. So, although we talk about 802.11g,
for example, being 54–110 Mbps in speed, the
reality is that unless you’re very close to the AP,
you’re not likely to get that maximum rate.
Signal fade and interference cut into your
speeds, and the negotiated rate between the
two devices drops.
That discussion represents just the speed. The
actual throughput is another, related, matter.
Throughput represents the rate at which the
validated data flows from one point to another.
It may take some retransmissions for that to
occur, so your throughput is less than the negotiated
speed of the connection. It may not be
unusual for you to get only 40 to 50 percent of
your maximum connection speed. In fact, that’s
rather normal.
� Channels: 802.11n gear can use either the 2.4 or the 5 GHz channels, providing
it with a considerably larger number of channels to choose from
when looking for the best connection between stations on your wireless
network (something 802.11n gear does automatically). The highest
speeds of 802.11n also use something called channel bonding, where
more than one channel is used at the same time, to increase the amount
of data sent across the network.
As a cost-saving measure, some 802.11n gear uses only 2.4 GHz frequencies.
This equipment won’t be able to use those relatively wide open
5 GHz channels but can still use the channel bonding feature for faster
connections. Note that 802.11n gear that uses only the 2.4 GHz frequencies
is not backward compatible with 802.11a (see the next bullet for
more on this).
� Backward compatibility: 802.11n gear is backward compatible with any
802.11b or 802.11g gear, so your older network adapters will still work
on a new 802.11n network. If your 802.11n router or access point works on
the 5 GHz frequency range, it will also be backward compatible with
802.11a gear.
Adding 802.11a/b/g gear to an 802.11n network will slow down the whole
network to a degree, but your network will still be faster than an 802.11a,
b, or g network.
� Cost: Because it’s a new technology, 802.11n equipment is about two to
three times more expensive than 802.11g equipment. For example, the
most popular 802.11n router on the market (Apple’s AirPort Extreme
with Gigabit Ethernet) is about $175, while the average 802.11g router