Wireless Channels

RF channels are important parts of wireless communications. A channel is the frequency band used for the wireless communication. Each standard specifies the channels that can be used. The 802.11a standards specifies radio frequencies ranging between 5.15 and 5.875GHz. In contrast, 802.11b and 802.11g standards operate between the 2.4 to 2.497GHz range. As far as channels are concerned, 802.11a has a wider frequency band, allowing more channels and therefore more data throughput. As a result of the wider band, 802.11a supports up to eight nonoverlapping channels. 802.11b/g standards use the smaller band and support only up to three nonoverlapping channels.

It is recommended that the nonoverlapping channels be used for communication. In the United States, 802.11b/g uses 11 channels for data communication as mentionedthree of these, channels 1, 6, and 11, are nonoverlapping channels. Most manufacturers set their default channel to one of the nonoverlapping channels to avoid transmission conflicts. With wireless devices, you have the option of selecting which channel your WLAN operates on in order to avoid interference from other wireless devices that operate in the 2.4GHz frequency range.

When troubleshooting a wireless network, be aware that overlapping channels can disrupt the wireless communications. For example, in many environments, APs are inadvertently placed closely together. Perhaps two access points in separate offices are located next door to each other or between floors. Signal disruption will result if there is channel overlap between the access points. The solution here is to try and move the access point to avoid the problem with the overlap or change channels to one of the other nonoverlapping channels. For example, switch from channel 6 to channel 11.

As far as troubleshooting is concerned, you would typically only change the channel of a wireless device if there is a channel overlap with another device. If a channel must be changed, it must be changed to another nonoverlapping channel.