Saturday 17 March 2012

Wireless Protocols and Basics of wireless protocols (WLAN 802.11a/b/g/n)

Wireless Protocols and Basics of wireless protocols (WLAN 802.11a/b/g/n)

IEEE Wireless Standards, amendments and recommended practices.
The actual standard with which all this started is IEEE 802.11-1997. This is the base standard after that all are are amendment
to this standard.
The nomenclature is a lowercase letter designates an amendment and a capital letter designates a recommended practice e.g 802.11a is amendment but 802.11F and 802.11T are  recommended practices.
Below is the list of all standard till date ( 2011, Oct )

802.11 — Released in 1997. This original MAC protocol specification includes the base functionality
along with FHSS and DSSS PHY.This standard offers throughputs up to 2Mbps.
802.11a — Defines the use of OFDM modulation in 5 GHz band with data rates up to 54 Mbps.
802.11b — Defines support for DSSS with CCK rates - 5.5 and 11 Mbps in 2.4 GHz to extend throughputs
from 2Mbps to 11Mbps in 2.4GHz band.
802.11c — Defines MAC bridging for 802.11 stations. This functionality is incorporated into 802.1d.
802.11-1999 — Contains 802.11 prime with all above enhancements.
802.11d — Defines support for world-wide WLAN operation by introducing new regulatory domains through
‘country’ code information element.
802.11e — Defines packer classification and prioritization to support Quality of Service (QoS)
for multimedia applications such as real time voice and video applications.
The important amendments rolled into WMM specification by Wi-Fi Alliance.
802.11F — Includes Inter-Access Point Protocol (IAPP) for interoperability
between different vendor Access Point products.Withdrawn in Feb 2006 and is not used now.
802.11g — Defines OFDM operation in 2.4GHz by introducing Extended Rate PHY (ERP),
 which extends throughputs in 2.4GHz band to 54Mbps.
802.11-R2003 — Rolled up 802.11-1999 and prior amendments, excluding 802.11e.
802.11h — Defines Transmit Power Control (TPC) for managing transmit power for 802.11 clients,
and Dynamic Frequency Selection (DFS) for radar detection and avoidance in some 5 GHz bands( 802.11 a) .
802.11i — Defines security enhancements to the previous and broken security
specification based on Wired Equivalent Protocol (WEP). It defines Wi-Fi Protection Access (WPA2)
with the use of Advanced Encryption Standard (AES) and 802.1X Extended Authentication Protocol (EAP).
802.11j — Defines WLAN operation in 4.9 to 5 GHz band in Japan. This standard is applicable only to Japan.
802.11-2007 — Rolled up 802.11-R2003 with earlier amendments.
802.11k — Defines radio resource management (RRM) methods for spectrum or RF data collection
and sharing between client and AP. This standard is for enablement of noise-free operation in enterprise WLAN networks.
802.11l — This standard is not in use as it is bypassed due to potential ambiguity and
confusion between the letter “l” and number “1”.
802.11m — This standard is used as a “maintenance” amendment to the 802.11 standard for updating inaccuracies,
omissions, and ambiguities.
802.11n — Defines High Throughput (HT) PHY with data rates up to 600 Mbps in 2.4 GHz and 5 GHz bands
through Media Access Control (MAC) level enhancements and Multiple Input and Multiple Output (MIMO) techniques.
802.11o — For the reasons mentioned for 802.11l, this standard is skipped due to potential ambiguity and confusion
between the letter “o” and number “0”.
802.11p — Defines the wireless access in vehicular environments (WAVE) to support Intelligent Transportation Systems (ITS)
 applications by enabling high speed vehicles to exchange data in the licensed 5.85 to 5.925GHz band.
802.11q — This standard is bypassed as there is a potential confusion of this standard with the existing
802.1Q standard defined for VLAN tagging.
802.11r — Defines fast and secure roaming of mobile clients from one Access Point (AP) to other, seamlessly.
This standard addresses the jitter and latency issues associated with voice and video applications during
 roaming from one AP to other.

802.11s — Defines the support for “standard based” mesh networking for wireless devices to interconnect
with each other to form a WLAN mesh network.

802.11T — Defines the recommended ways and practices for testing wireless performance in a predictable manner.
802.11T is cancelled and it doesn’t exist now.

802.11u — Defines internetworking with external networks( wireless internetworking with external networks), such as cellular networks. This standard covers
enablement of emergency call and alert services without having prior authentication from the user to the Wi-Fi network.

802.11v — Defines enhancements for advanced Wi-Fi network management. It includes the specification of
configuring and managing the client devices while they are connected to the Access Point.The 802.11v group is dependent on the 802.11k group, which is defining measurements that
 will be incorporated into the management interface being defined by 802.11v. 

802.11w — Defines protected management frames for all 802.11 standards. The 802.11i covers the security aspect of the ‘Data’ frames,
but all 802.11 management frames are not protected and they are subject to vulnerability. This standard protects against DoS(Denial of Service) attacks and network disruptions caused by spurious or forged management frames as they are not protected.

802.11x — This name can be used to refer whole family of 802.11 technologies collectively. So this standard/name is bypassed.

802.11y — Defines use of OFDM and high power WLAN devices in 3.65-3.7GHz band by changing Media Access Control (MAC) timings
. Unlike traditional WLAN devices, the devices in this band are allowed to transmit at high power.
As a result, the devices can operate at distances up to 5km, unlike up to 100m supported by today’s devices
operating in ISM band.

802.11z — Defines enhancements to peer-to-peer Direct Link Setup (DLS), by extending the DLS to be independent
of Access Point. This amendment defines a mechanism to tunnel the protocol messages through data frames for
establishing peer-to-peer link to improve the video performance between clients.

802.11aa — This amendment defines enhancements to video transport streams.

802.11ab — This amendment is bypassed to avoid confusion with devices using 802.11a and 802.11b technologies, which are often abbreviated as 802.11ab.

802.11ac — This amendment defines Very High Throughput (VHT) techniques to support speeds up to one gigabit per second (Gbps)
in below 6GHz frequency bands. It defines the use of wider bandwidth up to 160MHz, MIMO streams up to 8, and high-density
modulation up to 256-QAM to achieve 1Gbps performance.

802.11ad — This amendment defines super-fast WLAN operation with up to 7 Gbps throughputs in 60GHz.
802.11ae — Defines enhancements for managing QoS on WLAN networks. Note that 802.11e defines the base QoS for WLAN networks.

802.11af — Defines the use of Wi-Fi in newly opened TV white space frequencies between 50 and 600MHz, the available bandwidth
in this band is scattered,with handful of 6MHz wide channels.
The application throughputs will be relatively lower compared to 802.11a/g standards.As this is a low frequency band,
the range/coverage would be fantastic due to signal penetration.This standard can be used for rural broadband applications
where coverage is crucial and throughputs are less important.

802.11ag — Similar to 802.11ab, this standard is skipped to avoid potential confusion with devices using 802.11a and 802.11g PHY technologies, which are often abbreviated as 802.11ag.

802.11ah — Define the use of WLAN technology in frequencies below 1 GHz. 
802.11 ai - This standard is used for fast initial link setup.

The above list should be used as a reference to know about IEEE Wireless Standards, amendments and recommended practices.