IEEE 802.11
lastmod 2018-08-17created 2015-05-063 edits
IEEE 802.11 is a technology used in computer wireless networks for wireless local area networks (Local Area Network), commonly called wireless LAN or Wi-Fi, and refers to the standard developed by the 11th working group of the IEEE LAN/MAN Standards Committee (IEEE 802).
The terms 802.11 and Wi-Fi are sometimes used interchangeably, but the Wi-Fi Alliance defines the term "Wi-Fi" as a different set of standards. Therefore, 802.11 and Wi-Fi are not synonyms.
Overview
IEEE 802.11 is a technology designed to make up for the drawbacks of Ethernet, the wired LAN form mainly used today, and is widely used at the edge of Ethernet networks to minimize unnecessary wiring work and maintenance costs. Typically, one hotspot is installed in a large open space (for example, one office); the external WAN, backbone switch, and each office hotspot are connected via an Ethernet network, and the computers in each office connect wirelessly to the hotspot, so there is no need to go through the trouble of installing and maintaining cables inside the office.
IEEE 802.11ac
IEEE 802.11ac is one of the 802.11 wireless computer networking standards currently under development to provide high-speed local area networks (LAN). It supports high bandwidth (80MHz~160MHz) at the 5GHz frequency, and up to 40MHz bandwidth at 2.4GHz for compatibility with 802.11n. On January 20, 2011, the initial technical specification draft 0.1 was finalized by IEEE 802.11 TGac (the Task Group for ac). Completion of the standard is expected in late 2012, and final approval by the 802.11 committee in early 2014. According to research, 802.11ac devices are expected to become commonplace in 2015, with more than 1 billion spread worldwide.
Theoretically, under this specification, multi-station wireless LAN speeds of at least 1 Gbit/s and a maximum single-link speed of at least 500 Mbit/s become possible. This is achieved by extending the air interface concepts adopted in 802.11n: wider RF bandwidth (up to 160 MHz), more MIMO spatial streams (up to 8), multi-user MIMO, and high-density modulation (up to 256 QAM).