3. Getting Maximum Wireless Speed
802.11n wireless networking supports speeds
of up to 150Mbps, which is a huge improvement over older 801.11g and
802.11b equipment. However, you won’t get the maximum possible speed if
any of these conditions exist:
• There are other nearby networks using radio channels that overlap your network.
• You have older Wireless-G or -B equipment on the same network as -N (perhaps an old laptop or TiVo).
• You are using the insecure WEP or WPA security protocol (perhaps because you have older equipment that doesn’t support WPA2).
• You are using the WPA2/TKIP security setting.
• Your router is not using the legal maximum transmitting power.
The following sections tell you how to fix these conditions.
Eliminate Overlapping Channels
The 2.4GHz band used by wireless gear
supports 11 to 14 radio frequency channels so that you don’t have to
share radio bandwidth with your neighbors. The surprising fact is that
many of these channels overlap each other to a large extent—a given
channel overlaps about two and a half channels on either side. If your
neighbor’s wireless router is using channel 1, and you set your router
to use channel 2, there can still be considerable interference, and
both networks will be slowed down if you’re both using them at the same
time.
To avoid this, right-click the very bottom-left corner of the screen and select Command Prompt. Type netsh wlan show networks mode=bssid
and press Enter. This will list each neighboring network, its signal
strength (as a percentage of something—what, I don’t know), and its
channel. Examine the list, ignoring your own network. Select a channel
for your network that doesn’t conflict with at least the strongest of
your neighbors’ networks.
In the U.S., Canada, and Mexico, if you are
using Wireless-G, or a standard 20MHz bandwidth Wireless-N router, try
to select from channels 1, 6, and 11 only. Try to pick a channel that’s
five channels away from any strong neighboring signals.
If you are using a double-rate 40MHz
bandwidth 2.4GHz Wireless-N router, use either channel 3 or 11. In
Europe and elsewhere, find out what channels are recommended in your
region.
Set your router to use this channel. Your other wireless devices will automatically catch on within minutes.
You could also repeat this exercise in the
5GHz band, if your router supports it. Many more channels are
available, and there’s much less overlap between them. Use a channel
several numbers away from any neighboring 5GHz networks.
Tune Up Wireless Security
If you want to get the best Wireless-N
performance, use the WPA2/AES security setting on your router. This
just requires a setting change on the router. The connecting devices
will work it out on their own.
If you have some equipment that doesn’t
support WPA2, you’ll get maximum performance if you set up to use a
separate, lower-speed network, as described in the next section.
Separate Your -N and -G/-B Networks
Wireless-N, -G, and -B equipment can all
interoperate; however, having lower-speed equipment can slow down the
performance of higher-speed equipment when both are transmitting at the
same time, and even for several seconds afterward. If you have mixed
equipment, there are two ways to get peak speed on your Wireless-N
network:
• Use a two-radio (simultaneous
dual-band) router. Set up different network names (SSIDs) for the two
frequency bands. Set all of your Wireless-N equipment to use the 5GHz
network, and all of your -B and -G equipment to use the 2.4GHz network.
This requires a two-radio router, however, and 5GHz signals don’t have
the same reach as 2.4GHz.
• Alternatively, use two routers: a Wireless-N router for your -N gear, and an inexpensive -N or -G router for your other gear.
To set this up, configure the first
Wireless-N router as your primary wireless network. Choose a clear
channel, as described previously, and give it a network name (SSID)
like “MyWirelessN.” Set it up with WPA2/AES security.
Configure the other router as an access
point. This turns off its routing features and turns it into a simple
“repeater.” Most routers can be set up this way; check the
instructions. Select a channel that doesn’t conflict with your other
router. (For example, in the U.S., if your main router is set for
channel 1, set this one to channel 6 or 13.) Give it a distinct SSID
name, like “MyWirelessG.” Set up WPA2/AES security if the router and
your -G and -B devices support it. Position it at least 6 feet away
from the other router. Now, just plug this device’s WAN port into one
of your first router’s LAN ports. Have your slower devices connect to
this alternative network name.
Use the Right Security Settings
For most routers, you’ll get maximum
throughput only if you have wireless security shut off entirely, or set
to use WPA2/AES security. We don’t recommend turning security off,
unless you have a really good reason to do so (for example, if the
network is for random passersby and guests to use, and is separated
from your Windows file sharing network by a router).
Otherwise, be sure to set the router for
WPA2/AES rather than WEP, WPA, or WPA2/TKIP. If your router doesn’t
support WPA2, get one that does. If you have network clients that don’t
support WPA2 (my old TiVo falls in this category), consider setting up
a separate network for those devices, as discussed in the previous
section.
Bump Up the Power?
Around the world, countries have differing
regulations for the allowed frequencies and maximum power that
unlicensed transmitters such as wireless routers can use. To play it
safe, most routers are shipped with settings that adhere to the lowest
common denominator, which means that your router might be operating at
a lower power than is legally permissible in your area. It can be worth
checking your router’s advanced wireless settings to see if there is a
setting for the regulatory domain (operating region) or the transmitter
power.
The rules for the maximum-allowed
power are esoteric, and the allowed wattage depends on the frequency
band and the efficiency (gain) of the antenna used. For most
antennas, in North America the maximum 2.4GHz power is 100mW. You might
bump the power up to 60mW to see if this improves your data speed. It
might not. (And for many routers, much more than 60mW could shorten the
life of the router and actually degrade the signal.) If increasing the
power doesn’t improve your data speed, put it back to the original
setting.
