802.11a
Both 802.11b and 802.11g share one problem: They live in the 2.4-GHz ISM band. Having only three non-overlapping channels can limit wireless LAN growth in an area—assuming that all 802.11 devices stay within those three channels and do not cause unnecessary interference. Even worse, the ISM band is not limited to 802.11 devices. A wide variety of transmitters—even microwave ovens—can use the 2.4-GHz band without any regard for channels at all.
With too few channels and the potential for interference, the 802.11a amendment was introduced to utilize the 5-GHz U-NII bands for wireless LANs. Only one of the four U-NII bands is designated as ISM, so the chance for non-802.11 interference is very low. In addition, many more channels are available ...
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