Editing Wi-Fi (section)

=== Waveband ===
{{Main|List of WLAN channels}}

The 802.11 standard provides several distinct [[radio frequency]] ranges for use in Wi-Fi communications: 900&nbsp;[[MHz]], 2.4&nbsp;GHz, 3.6&nbsp;GHz, 4.9&nbsp;GHz, 5&nbsp;GHz, 6&nbsp;GHz and 60&nbsp;GHz [[band (radio)|bands]].<ref>{{Cite web |url=https://www.radio-electronics.com/info/wireless/wi-fi/80211-channels-number-frequencies-bandwidth.php |title=Wi-Fi Channels, Frequencies, Bands & Bandwidths |website=Electronics Notes |language=en |access-date=18 August 2018 |archive-date=16 February 2018 |archive-url=https://web.archive.org/web/20180216081725/https://www.electronics-notes.com/articles/connectivity/wifi-ieee-802-11/channels-frequencies-bands-bandwidth.php |url-status=live }}</ref><ref>{{cite book | url=https://ieeexplore.ieee.org/document/7786995 | publisher=[[IEEE]] | date=14 December 2016 | doi=10.1109/IEEESTD.2016.7786995| isbn=978-1-5044-3645-8 | title=IEEE Standard for Information technology—Telecommunications and information exchange between systems Local and metropolitan area networks—Specific requirements - Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications }}</ref><ref>{{Cite news|url=https://www.lifewire.com/wireless-standards-802-11a-802-11b-g-n-and-802-11ac-816553|title=802.11 WiFi Standards Explained|work=Lifewire|access-date=18 August 2018|language=en|archive-date=12 December 2018|archive-url=https://web.archive.org/web/20181212063416/https://www.lifewire.com/wireless-standards-802-11a-802-11b-g-n-and-802-11ac-816553|url-status=live}}</ref> Each range is divided into a multitude of [[Channel (communications)|channels]]. In the standards, channels are numbered at 5&nbsp;MHz spacing within a band (except in the 60&nbsp;GHz band, where they are 2.16&nbsp;GHz apart), and the number refers to the centre frequency of the channel. Although channels are numbered at 5&nbsp;MHz spacing, transmitters generally occupy at least 20&nbsp;MHz, and standards allow for neighbouring channels to be bonded together to form a wider channel for higher throughput.

Countries apply their own regulations to the allowable channels, allowed users and maximum power levels within these frequency ranges. 802.11b/g/n can use the 2.4&nbsp;GHz band, operating in the United States under FCC [[Part 15]] rules and regulations. In this frequency band, equipment may occasionally suffer [[Interference (communication)|interference]] from microwave ovens,<ref name="scienceabc" /> [[cordless telephone]]s, [[USB 3.0]] hubs,<ref>{{cite web |url= http://www.usb.org/developers/docs/whitepapers/327216.pdf |title=USB 3.0 Radio Frequency Interference Impact on 2.4&nbsp;GHz Wireless Devices |website=USB.org |publisher=USB Implementers Forum |date=April 2012 |access-date=14 October 2019}}</ref> [[Bluetooth]] and other devices.<ref name="wired">{{Cite magazine|url=https://www.wired.com/2010/09/wireless-explainer/|title=Why Everything Wireless Is 2.4&nbsp;GHz|magazine=WIRED|access-date=18 August 2018|language=en-US|archive-date=26 July 2018|archive-url=https://web.archive.org/web/20180726115300/https://www.wired.com/2010/09/wireless-explainer/|url-status=live}}</ref>

Spectrum assignments and operational limitations are not consistent worldwide: Australia and Europe allow for an additional two channels (12, 13) beyond the 11 permitted in the United States for the 2.4&nbsp;GHz band, while Japan has three more (12–14).

802.11a/h/j/n/ac/ax can use the [[U-NII|5&nbsp;GHz U-NII band]], which, for much of the world, offers at least 23 non-overlapping 20&nbsp;MHz channels. This is in contrast to the 2.4&nbsp;GHz frequency band where the channels are only 5&nbsp;MHz wide. In general, lower frequencies have longer range but have less capacity. The 5&nbsp;GHz bands are absorbed to a greater degree by common building materials than the 2.4&nbsp;GHz bands and usually give a shorter range.

As 802.11 specifications evolved to support higher throughput, the protocols have become much more efficient in their bandwidth use. Additionally, they have gained the ability to [[Link aggregation|aggregate]] channels together to gain still more throughput where the bandwidth for additional channels is available. 802.11n allows for double radio spectrum bandwidth (40&nbsp;MHz) per channel compared to [[802.11a]] or 802.11g (20&nbsp;MHz). 802.11n can be set to limit itself to 20&nbsp;MHz bandwidth to prevent interference in dense communities.<ref>{{Cite web|url=https://www.cisco.com/c/en/us/products/collateral/wireless/aironet-1250-series/design_guide_c07-693245.html#_Toc309331071|title=802.11n Data Rates Dependability and scalability|publisher=[[Cisco]]|archive-url=https://web.archive.org/web/20170705034144/http://www.cisco.com/c/en/us/products/collateral/wireless/Aironet-1250-series/design_guide_c07-693245.html#_Toc309331071|archive-date=5 July 2017|url-status=live|access-date=20 November 2017}}</ref> In the 5&nbsp;GHz band, 20&nbsp;MHz, 40&nbsp;MHz, 80&nbsp;MHz, and 160&nbsp;MHz channels are permitted with some restrictions, giving much faster connections.

{|style="margin: 0 auto;"
| [[File:2.4 GHz spectrum example Screenshot.png|thumb|An example of 2.4&nbsp;GHz Wi-Fi spectrum]]
| [[File:5 GHz Wi-Fi spectrum screenshot.png|thumb|An example of 5&nbsp;GHz Wi-Fi spectrum]]
| [[File:Netgear-Nighthawk-AC1900-WiFi-Router.jpg|thumb|upright| This [[Netgear]] Wi-Fi router contains dual bands for transmitting the 802.11 standards across the 2.4 and 5&nbsp;GHz spectrums and supports MIMO.]]
| [[File:Huawei 4G+ Modem.jpg|thumb|upright| A dual-band cellular 4G+ Wi-Fi modem by Huawei]]
|}