In the United States and several other countries in the Americas, the Federal Communications Commission (FCC; http://www.fcc.gov) regulates RF frequencies, channels, and transmission power. In addition to the 2.4–2.5-GHz ISM band allocated by the ITU-R, the FCC has allocated the Unlicensed National Information Infrastructure (U-NII) frequency space in the 5-GHz band for wireless LAN use. U-NII is actually four separate sub-bands, as follows:
U-NII-1 (Band 1): 5.15 to 5.25 GHz
U-NII-2 (Band 2): 5.25 to 5.35 GHz
U-NII-2 Extended (Band 3): 5.47 to 5.725 GHz
U-NII-3 (Band 4): 5.725 to 5.825 GHz (also allocated as ISM)
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