FCC Regulations

One of the reasons that so many enthusiasts are drawn to 802.11 is because it operates in an “unlicensed spectrum,” where a license to operate from the FCC is not required. Unlike other wireless activities, such as radio or TV broadcasting, we do not need to purchase frequencies or pay a monthly service fee to use the airways for Wi-Fi.

While 802.11 operation is free from cost, it is important to remember that it is not free from regulations. The rules for operating RF equipment vary from country to country, depending on the local regulatory agency involved. In the United States, that agency is the Federal Communications Commission (FCC).The rules for operating 802.11b equipment fall under the 1985 Industrial, Scientific, and Medical (ISM) mandate, while the rules for operating 802.11a equipment fall under the 1997 Unlicensed – National Information Infrastructure (U-NII) mandate.

ISM regulations actually predate the existence of 802.11. ISM provides unlicensed spectrum in the 902–928MHz, 2.400–2.485GHz, and 5.725–5.850GHz ranges.These frequencies were put to work in a variety of capacities and introduced a large number of technological innovations such as pagers, microwave ovens, and cordless phones.The downside, of course, is that by the time 802.11 moved into the landscape, there were already a large number of users in the 2.4 GHz frequency space.

U-NII, on the other hand, was designed specifically for wireless data networking. If you think back to 1997, it was a time when there was a national movement to bring the Internet to schools across the country. Apple computer petitioned the FCC with the thought that the best way to “wire” the schools was to “unwire” them, and so the FCC granted frequencies in the 5.15–5.25 GHz, 5.25–5.35 GHz, and 5.725–5.825 GHz ranges specifically for this purpose. Smart decisions were made in an attempt to optimize the spectrum. For example, the “Lower Band” of four non-overlapping channels (5.15–5.25 GHz) was reserved for lower-power indoor devices (up to 50mW).The “Middle Band” of the four non-overlapping channels (5.25–5.35 GHz) was reserved for medium-power indoor/outdoor devices (up to 250mW). Finally, the “Upper Band” of the four non-overlapping channels (5.725–5.825 GHz) was reserved for higher-power outdoor devices (up to 1W). In this manner, long distance (high power) point-to-point links did not interfere with shorter range (lower power) wireless networks.