GENERAL INFORMATION:

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Short description of the standard

IEEE Std 802.11-1997 specifies a single Medium Access Control (MAC) sub layer and 3 Physical Layer Specifications.

The MAC

The MAC provides the following services:

  1. Authentication (station service)
  2. Deauthentication (station service)
  3. Privacy (station service)
  4. MSDU delivery (station service)
  5. Association (distribution system service)
  6. Disassociation (distribution system service)
  7. Distribution (distribution system service)
  8. Integration (distribution system service)
  9. Reassociation (distribution system service)

Stations can operate in two configurations:

  1. independent configuration; the stations communicate directly to each other, so there is no infra-structure need to be installed. That is why we called this "ad-hoc" networks. It is easy to operate, but the disadvantage is that the coverage area is limited. Stations in such configuration are in a Basic Service Set (BSS). Without the ESS (see below) the stations operate in an Independent BSS (IBSS).
  1. infra-structure configuration; the stations communicate to Access points which are part of a Distribution System. An Access point serves the stations in a BSS The set of BSSs are called Extended Service Set (ESS). Note that 802.11 only specifies the air-interface, that is the interface between stations and between stations and Access points. With a Distribution system, the coverage area can be extended to whatever the internals of the distribution system for instance with bridged wired LANs.

The standard provides the above mentioned services with the following functionality: roaming within a ESS, multiple data rates in BSSs and Power Management (stations can switch off their transceivers to conserve power).

The MAC protocol is Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA).

The standard includes a formal description of the MAC protocol using the SDL method standardized by the International Telecommunications Union, Section Telecommunication (ITU-T, formerly CCITT)

The Physical Layer

The standard provides 2 Physical layer specifications for radio, operating in the 2 400 - 2 483.5 MHz band (depends on local regulations) and one for infrared.

Frequency Hopping Spread Spectrum Radio PHY. This PHY provides for 1 Mbit/s (with 2 Mbit/s optional) operation. The 1 Mbit/s version uses 2 level Gaussian Frequency Shift Keying (GFSK) modulation and the 2 Mbit/s version uses 4 level GFSK.

Direct Sequence Spread Spectrum Radio PHY. This PHY provides both 1 and 2 Mbit/s operation. The 1 Mbit/s version uses Differential Binary Phase Shift Keying (DBPSK) and the 2 Mbit/s version uses Differential Quadrature Phase Shift Keying (DQPSK).

Infrared PHY. This PHY provides 1 Mbit/s with optional 2 Mbit/s. The 1 Mbit/s version uses Pulse Position Modulation with 16 positions (16-PPM) and the 2 Mbit/s version uses 4-PPM.
For more details, look at our tutorial.

Each PHY specification includes state diagrams to formally describe the protocols.

Tutorial of draft Standard IEEE 802.11/D3.0

This tutorial was given to IEEE P802 at the March 1996 meeting

It may therefore contain information that has since been changed in the standard

The following presentations are files in PDF format. (see below)

Part 1: General Introduction of the standard (Vic Hayes, Lucent Technologies)

Part 2: the Architecture (Greg Ennis)

Part 3: the MAC entity (Phil Belanger, Aironet and Wim Diepstraten, Lucent Technologies)

Part 4: the Frequency Hopping Spread Spectrum PHY (Naftali Chayat, BreezeCom)

Part 5: the Direct Sequence Spread Spectrum PHY (Jan Boer, Lucent Technologies)

A viewer and printer for files in PDF format is available, free of charge, from Adobe look for acrobat reader for your platform.

Status of the work of IEEE P802.11

IEEE Std 802.11-1997 should now be available.

A revised version of IEEE Std 802.11-1997 will be submitted to the September meeting of RevCom as a Proposed ANSI/IEEE Standard. The same document has been adopted by ISO/IEC JTC1/SC6 (the committee of the International Standards Organization / International Electrical Committee responsible for data communication) as International Standard 8802-11. The plan calls for publication of the combined document in October 1998, if the Standards Board approves the proposal.

In the mean time, the Working Group has selected the Harris/Lucent Technologies modulation scheme as the basis for their work on higher data rates in the 2.4 GHz band (project 802.11b, handled by TGb) and has selected the NTT/Lucent Technologies modulation scheme as the basis for their work on higher data rates in the 5 GHz band (project 802.11a handled by TGa).

Project 802.11c, a supplement to 802.1d to support 802.11 frames, has sent their output to the September meeting of RevCom as a Proposed ANSI/IEEE Standard. The supplement is a set of instruction what to change to in the base standard. As such it will NOT be published as a separate document. If approved by the Standards Board, the changes will be reflected in the next issue of ISO/IEC 15802-3, which is the combined IEEE/ANSI and ISO/IEC version of the IEEE standard.

On future work

Refer to Study Group.

Forthcoming meetings

  1. For the latest information on 802.11 meetings, please see our meeting plan.

For the future Plenary meetings, look at the 802 meeting plan.

About 802.11 and how to participate

Currently, IEEE P802.11 has 98 voting members, 19 nearly-voting members and 57 aspirant voting members. (for information about the categories of members)

For more information.

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