Using the best channels has a big effect on network performance. Your goal is to choose settings that avoid interference from other networking and radio frequency equipment. (If you have 802.11a or 802.11a/g, channel selection is less important, skip to "Reducing Wireless Network Traffic".)

If you have a simple home network, and aren't close to neighbors with wireless equipment, you may be lucky enough just to choose between many channels that work well.

Complications arise when:

• You want much better coverage than you're getting.
• You use multiple access points or wireless routers. (Then you'll probably be using more than one channel.)
• You aren't the only person nearby running a wireless network.

Simple Spacing of Channels

As explained in Improving Wireless Range: Overview, improving signal strength is not like adding more lights to get a brighter livingroom. Devices that transmit powerfully — such as routers, access points, and cell phone base stations — confuse one another. It's necessary to distance them and to have them use different channels.

For 802.11b and 802.11g, there are 11 channels for wireless equipment (13 channels in Europe). In the simple situation where there's little interference, you can choose any channel that works for you. When there is interference from wireless networks that overlap with one another, each network should use one of the non-overlapping channels: 1, 6, or 11 (1, 7, 13 in Europe). Then, 3 networks can use the same space with minimum interference. If you can't do that, choose channels as widely spaces as possible.

You can use a combination of access points and antennas and other equipment to create local "spotlights" of strong transmission, rather than trying to cover everywhere.

What If a Channel I Want to Use Has Too Much Noise (Interference)?

If your neighbor has a wireless network, it wouldn't be surprising that they are already using channel 1 and channel 11. Unfortunately, you can't completely avoid interference just by using other channels. Wireless protocols 802.11b and 11g only have 3 non-overlapping channels. Therefore when 4 or more channels are used in the same area, the level of interference can increase notably. If you and your close neighbor both have a router and a wireless access point, for example — which makes a total of four powerful transmitters — both of you will have a certain amount of interference.

If there's a severe problem, a practical and sociable thing is to talk to your neighbors using wireless networks that can be seen when you scan. Together, you can choose optimal channels for your respective networks. You'll want your own channels at least 5 apart. So, for example, you could use channels 1 and 8, and your neighbor could use 5 and 11.

You may be able to place routers and access points further away inside your homes. After all, the kinds of physical barriers that reduce your transmission range also reduce the signal that your neighbor doesn't want to see.

If you can use a directional antenna, or an antenna cable to shift an antenna, that can help you both. See the articles on antenna selection.

Reducing Wireless Network Traffic

When there's noise, your network performance drops, so one approach is not to stop the noise, but to reduce the amount of network data being transmitted.

In a noisy environment, it may be useful to keep part of your network wired. If Ethernet cabling isn't an option, consider NETGEAR's Powerline products — using existing home wiring instead of cables.

When SSID Broadcast is turned on, it's easiest for equipment to find the strongest signal. However this also causes network overhead. When the SSID is broadcast, your neighbor's equipment may keep a record of it, and automatically try to connect several times a second; this can cause significant performance reduction. So where there are close networks, turn off SSID Broadcast, and change the default SSID.

Turning off WEP and WPA may increase network throughput, but exposes your network to hackers. This is not recommended, except for testing purposes.

Doc: n101318.asp May 11, 2004