List of WLAN channels
The 802.11 workgroup currently documents use in four distinct frequency ranges: 2.4 GHz, 3.6 GHz, 4.9 GHz, and 5 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.
2.4 GHz (802.11b/g/n)
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).
Note that for 802.11g/n it is not possible to guarantee OFDM (Orthogonal Frequency-Division Multiplexing) operation thus affecting the number of possible non-overlapping channels depending on radio operation.
As the protocol requires 16.25 to 22 MHz of channel separation (as shown above), adjacent channels overlap and will interfere with each other. Leaving 3 or 4 channels clear between used channels is recommended to avoid interference. The exact spacing required depends on the protocol and data rate selected as well as the electromagnetic environment where the equipment is used.
When two or more 802.11b transmitters are operated in the same airspace, their signals must be attenuated by -50dBr and/or separated by 22 MHz to prevent interference. This is due to fact that the DSSS algorithm transmits data logarithmically along a 20 MHz bandwidth. The remaining 2 MHz gap is used as a guard band to allow sufficient attenuation along the edge channels.
Note: The 40 MHz bands in the diagram above are labelled with their centre channel numbers, the management interface of many Wi-Fi devices labels these bands with the centre channel of one of the 20 MHz bands they overlap plus an Up or Down notation to specify the other half of the band i.e.: Channel 3 = Channel 1+Upper, or Channel5+Lower and Channel 11 = Channel 9+Upper or Channel 13+Lower.
Countries apply their own regulations to both the allowable channels, allowed users and maximum power levels within these frequency ranges. Network operators should consult their local authorities as these regulations may be out of date as they are subject to change at any time.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 world
^B In the USA, 802.11 operation in the channels 12 and 13 are 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|
4.9 GHz (802.11y) Public Safety WLAN
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. Network operators should consult their 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 GHz band is optional. DFS is required only in 5.470–5.725 GHz band.
Australian DFS channels also require TPC, or the maximum allowed power is cut in half. As per AS/NZS 4268 B1 and B2, transmitters designed to operate in any part of 5250–5350 MHz and 5470–5725 MHz bands shall implement DFS in accordance with sections 4.7 and 5.3.8 and Annex D of ETSI EN 301 893 or alternatively in accordance with FCC paragraph 15.407(h)(2). Also as per AS/NZS 4268 B3 and B4, transmitters designed to operate in any part of 5250–5350 MHz and 5470–5725 MHz bands shall implement TPC in accordance with sections 4.4 and 5.3.4 of ETSI EN 301 893 or alternatively in accordance with FCC paragraph 15.407(h)(1).
|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|
|149||5745||Yes||in study, SRD (25 mW)||No||No||Yes||Yes||No||Yes||No||Yes||No||Yes|
|153||5765||Yes||in study, SRD (25 mW)||No||No||Yes||Yes||No||Yes||No||Yes||No||Yes|
|157||5785||Yes||in study, SRD (25 mW)||No||No||Yes||Yes||No||Yes||No||Yes||No||Yes|
|161||5805||Yes||in study, SRD (25 mW)||No||No||Yes||Yes||No||Yes||No||Yes||No||Yes|
|165||5825||Yes||in study, SRD (25 mW)||No||No||Yes||Yes||No||Yes||No||Yes||No||Yes|
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 126.96.36.199.3 lists permitted channels.
- Electromagnetic interference at 2.4 GHz
- High Speed Multimedia Radio
- List of WLAN frames
- Wireless LAN
- "IEEE 802.11-2007: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications". IEEE. 2007-03-08.
- "IEEE 802.11-2012: 16.4.6 - PMD Operating Specifications, General". IEEE. 2013-05-15.
- "Change the WiFi Channel Number to Avoid Interference".
- IEEE 802.11-2007 — Table 18-9
- France: "WLAN regulatory update". 2003-02-03.
- Spain: http://web.archive.org/web/20080206082504/http://www.mityc.es/Telecomunicaciones/Secciones/Espectro/cnaf/
- Israel: "צו הטלגרף האלחוטי (אי תחולת הפקודה) (מס' 2), התשס"ו – 2005" (in hebrew).
- Australia: "Radiocommunications (Low Interference Potential Devices) Class Licence 2000". comlaw.gov.au. Retrieved 2011-03-28.
- "Brazil: Resolução nº 506, de 01/07/2008, publicado no Diário Oficial de 07/07/2008, atualizado em 24/11/2010 (in Brazilian Portuguese)". p. 33.
- 47 CFR §15.247
- "TCB workshop on unlicensed devices". October 2005. p. 58.
- NTIA comments to the FCC ET Docket 03-108, footnote 88
- "Cisco Enterprise Mobility 4.1 Design Guide, Chapter 3: WLAN Radio Frequency Design Considerations". p. 3.
- IEEE 802.11-2007 Annex J modified by amendments k, y and n.
- FCC 15.407 as of June 23, 2011 – hallikainen.com / See paragraph 'h'
- FCC Publication - 443999 D01 Approval of DFS UNII Devices v01
- Bundesnetzagentur Vfg 7/2010 / See footnote 4 and 5 (german only)
- 2005/513/EC: Commission Decision of 11 July 2005 on the harmonised use of radio spectrum in the 5 GHz frequency band for the implementation of wireless access systems
- 2007/90/EC: Commission Decision of 12 February 2007 amending Decision 2005/513/EC on the harmonised use of radio spectrum in the 5 GHz frequency band for the implementation of Wireless Access Systems
- Information der Obersten Fernmeldebehörde - Drahtlose lokale Netzwerke (WAS, WLAN, RLAN)(german only)
- Frequency assignments for unlicensed devices / See page 14
- FCC 15.407 as of April 9, 2013 – hallikainen.com
- 802.11-2007 Japan MIC Released the new 5 GHz band (W56). Bureau Veritas — ADT. Retrieved 2008-02-23.
- "IDA Singapore: Spectrum Management Handbook". May 2011. p. 30.
- Korea Frequency Distribution Table 2008.12.31 (in Korean)
- KISA MESAFE ERİŞİMLİ TELSİZ CİHAZLARI (KET) YÖNETMELİĞİ Resmi Gazete 10.03.2010 Madde 8 - Genişband veri iletim sistemleri (in Turkish)
- "Elimination of interference to Terminal Doppler Weather Radar (TDWR)". Retrieved 2012-12-27.
- "Relating to the use of Short Range Devices (SRD)". ECC. October 9, 2012. Retrieved 2013-02-08.