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Get The Interference Out Of Your WLAN

Wi-Fi networks, Bluetooth devices and cordless phones use radio waves that fall within a non-licensed portion of the frequency spectrum. This means that the Federal Communications Commission (FCC) in the U.S. and regulatory bodies in other countries allow usage in these public bands without coordination among users.

This situation occasionally results in radio wave signals from other sources hurting the performance of Wi-Fi networks, a problem generically known as RF interference. That's why it's important to consider all potential sources of RF interference when deploying a wireless LAN. If you don't, you are likely to see a precipitous drop-off in performance that, in some cases, you may not be able to fix.

Where Interference Comes From

Most RF interference impacts wireless LANs that operate in the 2.4GHz band, which 802.11b and 802.11g networks utilize. For example, a company may install an 802.11b/g wireless LAN and set all of the access points to the same channel.

In this case, the access points and the users associated with them politely take turns using the same part of the frequency spectrum. With only a few users active on the network, the impact on performance is barely noticeable. In fact, tests I've conducted indicate only 10 percent lower throughput when three or fewer users are actively sending packets. Higher utilization decreases throughput substantially more, however, due to greater latency in accessing the medium.

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