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The 802.11 workgroup currently documents use in three distinct frequency ranges, 2.4 GHz, 3.6 GHz and 4.9/5.0 GHz bands. Each range is divided into a multitude of channels. Countries apply their own regulations to both the allowable channels, allowed users and maximum power levels within these frequency ranges. In some countries, such as the United States, licensed Amateur Radio operators may use some of the channels at much higher power for long distance wireless access.
There are 14 channels designated in the 2.4 GHz range spaced 5 MHz apart (with the exception of a 12 MHz spacing before Channel 14). As the protocol requires 25 MHz of channel separation, adjacent channels overlap and will interfere with each other. Consequently, using only channels 1, 6, 11 is recommended in the US to avoid interference. In much of the world, the four channels 1, 5, 9, 13 are recommended. There are exceptions to this however, for example in the UK, where British Telecom recommend use of three channels 1, 6, 11. Using the 3-channel system is recommended, since many existing access points are on channel 6 by factory default, causing the channel 6 to be likely to be in use anyway.
Potential Wireless LAN by IEEE 802.11 clauses 18 (802.11b), 19 (802.11g) and 20 (802.11n). IEEE 802.11 clauses 14 and 15 also specify potential uses of this range, but did not see widespread implementation.
Countries apply their own regulations to both the allowable channels, allowed users and maximum power levels within these frequency ranges. Consult your local authorities as these regulations may be out of date as they are subject to change at any time. Most of the world will allow the first thirteen channels in the spectrum.
|Japan||Most of worldA|
|*With 802.11g and newer only the channels 1, 5, 9, and 13 shall be used in order to obey the non-overlapping 20 MHz OFDM channel scheme borrowed from 802.11a. But please do a site survey first, then if channel 6 is already heavily occupied, follow the 3-channel system.|
^A Earlier, in Spain the only allowable channels were 10–11, and in France 10–13. These restrictions have been removed since, and these countries are currently following the common European policy (channels 1–13).
^B In the USA, 802.11 operation in the channels 12 and 13 is actually allowed under low powered conditions. The 2.4 GHz Part 15 band in the US allows spread-spectrum operation as long as the 50-dB bandwidth of the signal is within the range of 2,400–2,483.5 MHz which wholly encompasses both channels 12 and 13. A Federal Communications Commission (FCC) document clarifies that only channel 14 is forbidden and furthermore low-power transmitters with low-gain antennas may legally operate in channels 12 and 13. However, channels 12 and 13 are not normally used in order to avoid any potential interference in the adjacent restricted frequency band, 2,483.5–2,500 MHz, which is subject to strict emission limits set out in 47 CFR §15.205.
In Canada, 12 channels are available for use, 11 of which at full power and the other (channel 12) is transmit power limited. However, few devices have a method to enable a lower powered channel 12[opinion].
Except where noted, all information taken from Annex J of IEEE 802.11y-2008
This range is documented as only being allowed as a licensed band in the United States. Please see IEEE 802.11y for details.
Countries apply their own regulations to both the allowable channels, allowed users and maximum power levels within these frequency ranges.
|5 MHz||10 MHz||20 MHz|
50 MHz of spectrum from 4940 MHz to 4990 MHz (WLAN channels 20–26) are in use by public safety entities in the United States. Within this spectrum space, there are two non-overlapping channels allocated, both with a width of 20 MHz. The most commonly used channels are 22 and 26.
Countries apply their own regulations to both the allowable channels, allowed users and maximum power levels within these frequency ranges. Consult your local authorities as these regulations may be out of date as they are subject to change at any time.
European standard EN 301 893 covers 5.15-5.725 GHz operation, and v1.7.1 is in force.
In 2007 the FCC (United States) began requiring that devices operating on 5.250–5.350 GHz and 5.470–5.725 GHz must employ dynamic frequency selection (DFS) and transmit power control (TPC) capabilities. This is to avoid interference with weather-radar and military applications. In 2010, the FCC further clarified the use of channels in the 5.470–5.725 GHz band to avoid interference with Terminal Doppler Weather Radar (TDWR) systems. This statement eliminated the use of channels 120, 124, and 128. Channels 116 and 132 may be used, so long as they are separated by more than 30 MHz (center-to-center) from a TDWR located within 35 km of the device. There are now at least five relevant KDBs about operation in 5 GHz radar bands.
Germany requires dynamic frequency selection (DFS) and transmit power control (TPC) capabilities on 5.250–5.350 GHz and 5.470–5.725 GHz as well, in addition the frequency range 5.150–5.350 GHz is only allowed for indoor use, leaving only 5.470-5.725 GHz for outdoor and indoor use.
Austria adopted Decision 2005/513/EC directly into national law. The same restrictions as in Germany apply, only 5.470-5.5725 GHz is allowed to be used outdoor and indoor.
South Africa simply copied the European regulations.
Japan no longer allows 34, 38, 42, and 46 channels for connecting J52 supported old APs. Authorization to use these channels expired in May 2012.
In Brazil, the TPC use in 5,150–5,725 MHz band is optional. DFS is required only in 5,470–5,725 MHz band.
Australian DFS channels also require TPC, or the maximum allowed power is cut in half.
|United States||Europe||Japan||Singapore||China||Israel||Korea||Turkey||Australia||South Africa||Brazil|
|40/20 MHz||40/20 MHz||40/20 MHz||10 MHz||40/20 MHz||20 MHz||20 MHz||20 MHz||40/20 MHz||40/20 MHz||40/20 MHz||40/20 MHz|
|34||5170||No||No||Client only[clarification needed]||No||Yes||No||Yes||Yes||Indoors||No||Indoors||Indoors|
In Japan, authorization to use channels 34, 38, 42 and 46 expired in May 2012, seven years after channels 36, 40, 44 and 48 were initially allowed. ARIB STD T-71v5_2 clause 220.127.116.11.3 lists permitted channels.