Wireless Home Networking - Index of

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Part II: Making Plans
What to look for in 802.11n gear
The 802.11n draft standard has a bit more variation
in its specifications than previous 802.11
standards such as 802.11g. What this means is
that while all 802.11n gear will work at a certain
(very high) baseline of performance, some gear
may be more capable than others.
The biggest variation in the category of 802.11n
gear revolves around the frequencies used. All
802.11n gear works within the 2.4 GHz band that
was also used by 802.11b and 802.11g. Some —
but far from all — 802.11n equipment also works
in the 5 GHz frequency range that was previously
the sole domain of the 802.11a standard.
This higher frequency range is less crowded
with other wireless gear (such as cordless
phones and Bluetooth devices), so you’re less
likely to face interference. Additionally, the 5
GHz band has more channels (the frequency
band is divided into a number of channels),
making it even easier to find an uncrowded
frequency.
Most of this dual-band (2.4 and 5 GHz) 802.11n
gear today works in either one or another of the
frequency bands at a time. What this means is
that if you have any legacy 802.11b or g equipment
on your network, the 5 GHz capability of
your AP or router will not come into play. A few
APs and routers on the market (or soon to be on
the market as we write in late 2007) have the
capability to operate in both bands simultaneously.
This is a great capability to have in a
mixed 802.11g/802.11n network, because your
old gear can happily hum along at 802.11g
speeds by using the 2.4 GHz radio in your router,
while your fancy new 802.11n gear can reach
maximum 802.11n speeds in the 5 GHz band.
The final thing to look for when choosing
802.11n systems is the capability of the equipment
to perform channel bonding. All Wi-Fi
systems use 20 MHz wide channels to transmit
and receive data across the network airlink;
many 802.11n systems can bond two adjacent
channels together to form one bigger 40 MHz
channel. (For this reason, channel bonding is
sometimes referred to as 40 MHz channel
width.) This bigger, bonded channel can carry
more data and allow your system to reach the
higher (200+ Mbps) speeds promised by
802.11n.
By the way, significantly more channels are
available for bonding in the 5 GHz frequency
range, which is another reason to choose a
dual-band system.
USB comes in two versions: USB 1.1 and USB 2.0. If your computer has a
USB 1.1 port, it has a maximum data-transfer speed of 12 Mbps. USB 2.0
ports can transfer data at 480 Mbps, which is 40 times faster than USB 1.1.
If you plan to connect an 802.11g or n device to a USB port, it must be
USB 2.0.
Many brands of PC Cards include antennas enclosed in a casing that is
thicker than the rest of the card. The card still fits in the PC Card slot,
but the antenna can block the other slot. For most users, this shouldn’t
pose a serious problem; however, several manufacturers offer wireless
PC Cards that have antenna casings no thicker than the rest of the card.
If you actively use both PC Card slots (perhaps you use one for a FireWire
or USB 2.0 card), make sure that the form of the PC Card you’re buying
doesn’t impede the use of your other card slot.