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Wireless LAN (WLAN) channels are frequently accessed using IEEE 802.11 protocols. The 802.11 standard provides several radio frequency bands for use in Wi-Fi communications, each divided into a multitude of channels numbered at 5 MHz spacing (except in the 45/60 GHz band, where they are 0.54/1.08/2.16 GHz apart) between the centre frequency of the channel.
802.11a uses the 5 GHz U-NII band which, for much of the world, offers at least 23 non-overlapping, 20-MHz-wide channels. This is an advantage over the 2.4-GHz, ISM-frequency band, which offers only three non-overlapping, 20-MHz-wide channels where other adjacent channels overlap (see: list of WLAN channels). Better or worse performance with ...
Bluetooth devices intended for use in short-range personal area networks operate from 2.4 to 2.4835 GHz. To reduce interference with other protocols that use the 2.45 GHz band, the Bluetooth protocol divides the band into 80 channels (numbered from 0 to 79, each 1 MHz wide) and changes channels up to 1600 times per second.
This spectrum was added by the FCC in 2003 to "align the frequency bands used by U-NII devices in the United States with bands in other parts of the world". [5] The FCC currently has an interim limitation on operations on channels which overlap the 5600–5650 MHz band. [6] U-NII Upper (U-NII-3 [7]): 5.725–5.850 GHz.
IEEE 802.11n is an amendment to IEEE 802.11-2007 as amended by IEEE 802.11k-2008, IEEE 802.11r-2008, IEEE 802.11y-2008, and IEEE 802.11w-2009, and builds on previous 802.11 standards by adding a multiple-input multiple-output (MIMO) system and 40 MHz channels to the PHY (physical layer) and frame aggregation to the MAC layer.
For wider area communications, wireless local area network (WLAN) is used. WLANs are often known by their commercial product name Wi-Fi. These systems are used to provide wireless access to other systems on the local network such as other computers, shared printers, and other such devices or even the internet.
Dynamic Frequency Selection (DFS) is a channel allocation scheme specified for wireless LANs, commonly known as Wi-Fi. It is designed to prevent electromagnetic interference by avoiding co-channel operation with systems that predated Wi-Fi, such as military radar , satellite communication , and weather radar , and also to provide on aggregate a ...
Carrier frequency offset ... IEEE 802.11 WLAN specifies the ... The preamble is designed so that each transmit antenna uses non-overlapping sub carriers to facilitate ...