IEEE 802.11Standards

IEEE 802.11 Standards

• First published in June 1997.• Defines technologies at the Physical layer and the

MAC sublayer of the Data-Link layer. • The standard does not address the upper layers of

the OSI model.• The PHY Task Group has developed three Physical

layer specifications.

IEEE 802.11 StandardPHY Tack Group

• Infrared (IR): Uses a light-based medium.  This was the first medium standard.  By the time it was implemented, it was rendered obsolete.  

• Frequency Hopping Spread Spectrum (FHSS):  Defined as narrowband signals or as spread spectrum signals.  An RF signal is considered spread spectrum when the bandwidth of a signal is more than what is required for carrying data.

• Direct sequence spread spectrum (DSSS): Spread spectrum technology--easy to use and to implement.

continued...

• In 802.11 Prime, the frequency space of both FHSS or DSSS radio cards can be transmitted on is the Industrial, Scientific, and Medical (ISM) band.

• DSSS cards can transmit in channels that are subdivided from the 2.4 to 2.4835 GHz ISM band.

• FHSS can transmit at a 1 MHz subcarrier in the 2.402 to 2.480 GHz range of the ISM band.

• FHSS and DSSS cannot communicate with each other.

Ratified Amendments

ratify approve and express assent, responsibility, or obligation; "All parties ratified the peace treaty"

+ High data rates and backwards compatible+ Triggered huge sales of Wi-Fi gear in homes, offices and enterprise levels

802.11b + Achieved data rates up to

11 Mbps- Uses the same 2.4 GHz band as bluetooth, microwave etc...

+ Operates in 5 GHz band,  with a maximum raw data rate of 54 Mbit/s- Signals more readily absorbed by walls, but less interference from other devices

802.11a

802.11g

Wireless G Access Point

+ Defined mechanisms for DFS and TPC for operation in the 5 GHz band in Europe+ Some Vendors have applied TPC and DFS - like services to radios cards operating on 2.4 GHz ISM band

802.11d + Allowed 802.11 to

operate in areas not served by original standard+ Defined info specific for Frequency Hopping access points country to country

+ Mandated vendor access points to support roaming, access point hopping- Failed to dictate how roaming should actally transpire

802.11F

802.11h

Tesla's Oscillator

+ Defines the layer 2 MAC methods to meet QoS requirements for time-sensitive applications over wireless LANs.- Original standard defined DCF and PCF, which were not adequate for voice, audio, and video traffic

802.11i + Updated security from WEP to CCMP/AES and defined TKIP+ Required the use of an EAP, Extensible Authentication Protocol+ Defined method of establishing authentication. (RSN)

+ Main goal was to obtain Japanese regulatory approval by enhancing 802.11 to operate in Japanese 4.9 and 5 GHz bands+ "Tight" with the Japanese

802.11j

802.11e

Quality Control

Draft Amendments

       The 802.11 standard has been updated many times since the standard’s induction in 1997. The most popular changes to the standard are the 802.11a, 802.11g, and 802.11b amendments.

     With the release of 802.11a it allowed speeds up to 54Mbps placed in the 5 GHz range. The 802.11b amendment allowed for speeds up to 11 Mbps in the 2.4 GHz range. The ‘b’ was not compatible with the ‘a’ amendment because it operated at a different frequency, but it did allow the range to be increased to 300 feet.

     The 802.11g amendment was designed to over take the 802.11b amendment, allowed for speeds up to 54 Mbps in the 2.4 GHz range with enhanced security, and less overlapping channels.  Each major amendment gets a new letter; IEEE is currently in the process of working on amendment ‘n’ of the 802.11 standard.

      The new amendment offers a lot of changes from previous ones. The speeds of the data transfer will be almost twice the speed as previous versions. With theoretical speeds ranging up to 540 Mbps.

     There are some very interesting things happening in the planning of the new amendment. To help with the creation of the amendment, IEEE created the Enhanced Wireless Consortium (EWC), to maintain and implement the rest of the amendments that the company was going to put forth. It is the task force’s job to implement new technology, while upholding to previous versions of 802.11.

   The CPU manufacturer, Intel, is also currently a having a considerable amount of control in the creation of the amendment, pushing the amendment to go farther than previous expectations. (Wilson) Intel is pushing for faster speeds, and better reliability, and the use of MIMO technology. Intel was the producer of many of the technical documents used for the current drafts of the amendment. It is partly Intel’s fault that the amendment is taking so long to be released. Their goal is to test the new standard of 100 Mbps in the 2.4 GHz frequency range under many circumstances, ranging from home to public environments.