Wi-Fi/802.11x Standards

January 8 2018 , Written by Cisco & Cisco Router, Network Switch Published on #Networking, #IT, #Technology

Wi-Fi is so popular today. Do you know the Wi-Fi standards and how wifi works?

In the following part we will share the main information about the Wi-Fi standard (also called the 802.11x standard). The original info from

http://searchmobilecomputing.techtarget.com/definition/Wi-Fi

Wi-Fi is a term for certain types of wireless local area networks (WLAN) that use specifications in the 802.11 family--for example, Wi-Fi Direct, a peer-to-peer specification that allows devices certified for Wi-Fi Direct to exchange data without an internet connection or a wireless router.

Products that pass Wi-Fi Alliance tests for interoperability, security and application-specific protocols are labeled "Wi-Fi CERTIFIED," a registered trademark of the Alliance.

How does Wi-Fi work?

A Wi-Fi network uses radio waves to wirelessly transmit information across a LAN, the reach of which can be extended by a Wi-Fi range extender. A computer utilizes a wireless adapter to translate data transmitted by radio waves. These waves are different from those emitted by, for example, FM radios, for which frequency is measured in megahertz (MHz). Wi-Fi's signals are transmitted in frequencies of between 2.5 and 5 gigahertz (GHz). This signal is then transmitted from the adapter through a router, after which it is sent to the internet.

Wi-Fi is widely used in businesses, agencies, schools and homes as an alternative to a wired LAN. Many airports, hotels and fast-food facilities offer public access to Wi-Fi networks. These locations are known as hotspots. Many charge a daily or hourly rate for access, but some are free. An interconnected area of hotspots and network access points is known as a hot zone.

What are hotspots?

Modern smart phones and tablets are also able to turn into Wi-Fi hotspots, using their cellular network connections to provide wireless internet connectivity to computers and other devices.

To access Wi-Fi hotspots, computers should include wireless adapters. These can be found on laptops and mobile devices, such as tablets or mobile phones. If for some reason your computer doesn't include such an adapter, one can be purchased that can be inserted into the PCI slot or USB port. Your computer should then be able to locate Wi-Fi networks automatically in the area. These can either be open networks or protected networks; the latter can be joined by entering a Wi-Fi password.

Unless adequately protected, a Wi-Fi network can be susceptible to access by unauthorized users who use the access as a free internet connection. The activity of locating and exploiting security-exposed wireless LANs is called war driving. An identifying iconography, called war chalking, has evolved. Any entity that has a wireless LAN should use security safeguards, such as the Wired Equivalent Privacy, or WEP, encryption standard; the more recent Wi-Fi Protected Access, or WPA; Internet Protocol Security, or IPsec; or a virtual private network, or VPN.

The term Wi-Fi was created by the Wi-Fi Alliance as a play on Hi-Fi, an abbreviation for high fidelity, which referred to high-quality audio reproduction. Similarly, Wi-Fi is often thought to be short for wireless fidelity. However, according to the Wi-Fi Alliance, Wi-Fi is not an abbreviation. The confusion may stem from the fact that the Alliance briefly used, "The standard for wireless fidelity," as a slogan for Wi-Fi.

Originally, Wi-Fi certification was applicable only to products using the 802.11b standard.

Today, Wi-Fi can apply to products that use any 802.11 standard. The 802.11 specifications are part of an evolving set of wireless network standards known as the 802.11 family.

The particular specification under which a Wi-Fi network operates is called the "flavor" of the network.

802	Overview	Basics of physical and logical networking concepts
802.1	Bridging	LAN/MAN bridging and management. Covers management and the lower sublayers of OSI Layer 2, including MAC-based bridging (Media Access Control), virtual LANs and port-based access control.
802.2	Logical Link	Commonly referred to as the LLC, or Logical Link Control specification. The LLC is the top sublayer in the data-link layer, OSI Layer 2. Interfaces with the network Layer 3.
802.3	Ethernet	"Granddaddy" of the 802 specifications. Provides asynchronous networking using "carrier sense, multiple access with collision detect" (CSMA/CD) over coax, twisted-pair copper and fiber media. Current speeds range from 10 Mbps to 10 Gbps. Click for a list of the hot 802.3 technologies.
802.4	Token bus	Disbanded
802.5	Token ring	The original token-passing standard for twisted-pair, shielded copper cables. Supports copper and fiber cabling from 4 Mbps to 100 Mbps. Often called "IBM Token-Ring."
802.6	Distributed queue dual bus (DQDB)	"Superseded **Revision of 802.1D-1990 edition (ISO/IEC 10038). 802.1D incorporates P802.1p and P802.12e. It also incorporates and supersedes published standards 802.1j and 802.6k. Superseded by 802.1D-2004." (See IEEE status page.)
802.7	Broadband LAN practices	Withdrawn standard. Withdrawn date: Feb. 7, 2003. No longer endorsed by the IEEE. (See IEEE status page.)
802.8	Fiber optic practices	Withdrawn PAR. Standards project no longer endorsed by the IEEE. (See IEEE status page.)
802.9	Integrated services LAN	Withdrawn PAR. Standards project no longer endorsed by the IEEE. (See IEEE status page.)
802.10	Interoperable LAN security	Superseded **Contains: IEEE Standard 802.10b-1992. (See IEEE status page.)
802.11	Wi-Fi	Wireless LAN Media Access Control and Physical Layer specification. 802.11a,b,g,etc. are amendments to the original 802.11 standard. Products that implement 802.11 standards must pass tests and are referred to as "Wi-Fi-certified."
802.11a		Specifies a PHY that operates in the 5 GHz U-NII band in the U.S. -- initially 5.15-5.35 and 5.725-5.85 -- since expanded to additional frequencies; Uses Orthogonal Frequency-Division Multiplexing; Enhanced data speed to 54 Mbps; and Ratified after 802.11b.
802.11b		Enhancement to 802.11 that added higher data rate modes to the DSSS (Direct Sequence Spread Spectrum) already defined in the original 802.11 standard; Boosted data speed to 11 Mbps; 22 MHz bandwidth yields three nonoverlapping channels in the frequency range of 2.400 GHz to 2.4835 GHz; and Beacons at 1 Mbps, falls back to 5.5, 2 or 1 Mbps from 11 Mbps max.
802.11d		Enhancement to 802.11a and 802.11b that allows for global roaming; and Particulars can be set at Media Access Control layer.
802.11e		Enhancement to 802.11 that includes quality-of-service features; and Facilitates prioritization of data, voice and video transmissions.
802.11g		Extends the maximum data rate of WLAN devices that operate in the 2.4 GHz band, in a fashion that permits interoperation with 802.11b devices; Uses OFDM Modulation (Orthogonal FDM); and Operates at up to 54 (Mbps, with fallback speeds that include the "b" speeds.
802.11h		Enhancement to 802.11a that resolves interference issues; Dynamic frequency selection; and Transmit power control.
802.11i		Enhancement to 802.11 that offers additional security for WLAN applications; and Defines more robust encryption, authentication and key exchange, as well as options for key caching and preauthentication.
802.11j		Japanese regulatory extensions to 802.11a specification; and Frequency range of 4.9 GHz to 5.0 GHz.
802.11k		Radio resource measurements for networks using 802.11 family specifications
802.11m		Maintenance of 802.11 family specifications; and Corrections and amendments to existing documentation.
802.11n		Higher-speed standards; Several competing and noncompatible technologies -- often called "pre-n"; Top speeds claimed of 108, 240, and 350+ MHz; and Competing proposals come from the groups, EWC, TGn Sync and WWiSE, and are all variations based on MIMO (multiple input, multiple output).
802.11x		Misused generic term for 802.11 family specifications
802.12	Demand priority	Increases Ethernet data rate to 100 Mbps by controlling media utilization.
802.13	Not used	Not used
802.14	Cable modems	Withdrawn PAR. Standards project no longer endorsed by the IEEE.
802.15	Wireless personal area networks	Communications specification that was approved in early 2002 by the IEEE for wireless personal area networks, or WPANs.
802.15.1	Bluetooth	Short range (10m) wireless technology for cordless mouse, keyboard and hands-free headset at 2.4 GHz.
802.15.3a	UWB	Short-range, high-bandwidth ultra wideband link
802.15.4	ZigBee	Short-range wireless sensor networks
802.15.5	Mesh network	Extension of network coverage without increasing the transmit power or the receiver sensitivity; Enhanced reliability via route redundancy; and Easier network configuration and better device battery life.
802.16	Wireless metropolitan area networks	This family of standards covers Fixed and Mobile Broadband Wireless Access methods used to create wireless metropolitan area networks. Connects base stations to the internet using OFDM in unlicensed (900 MHz, 2.4, 5.8 GHz) or licensed (700 MHz, 2.5-3.6 GHz) frequency bands. Products that implement 802.16 standards can undergo WiMAX certification testing.
802.17	Resilient Packet Ring	IEEE working group description
802.18	Radio Regulatory TAG	IEEE 802.18 standards committee
802.19	Coexistence	IEEE 802.19 Coexistence Technical Advisory Group
802.20	Mobile Broadband Wireless Access	IEEE 802.20 mission and project scope
802.21	Media Independent Handoff	IEEE 802.21 mission and project scope
802.22	Wireless regional area network	IEEE 802.22 mission and project scope