IEEE 802.11 (legacy mode)

IEEE 802.11 (legacy mode)

IEEE 802.11 (legacy mode) — or more correctly IEEE 802.11-1997 or IEEE 802.11-1999 — refer to the original version of the IEEE 802.11 wireless networking standard released in 1997 and clarified in 1999. Most of the protocols described by this early version are rarely used today.

Description

It specified two raw data rates of 1 and 2 megabits per second (Mbit/s) to be transmitted via infrared (IR) signals or by either Frequency hopping or Direct-sequence spread spectrum (DSSS) in the Industrial Scientific Medical frequency band at 2.4 GHz. IR remains a part of the standard but has no actual implementations.

The original standard also defines Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) as the medium access method. A significant percentage of the available raw channel capacity is sacrificed (via the CSMA/CA mechanisms) in order to improve the reliability of data transmissions under diverse and adverse environmental conditions.

At least six different, somewhat-interoperable, commercial products appeared using the original specification, from companies like Alvarion (PRO.11 and BreezeAccess-II), BreezeCom, Digital / Cabletron (RoamAbout) , Lucent, Netwave Technologies (AirSurfer Plus and AirSurfer Pro), Symbol Technologies (Spectrum24), and Proxim Wireless (OpenAir and Rangelan2). A weakness of this original specification was that it offered so many choices that interoperability was sometimes challenging to realize. It is really more of a "beta-specification" than a rigid specification, initially allowing individual product vendors the flexibility to differentiate their products but with little to no inter-vendor operability.

The DSSS version of legacy 802.11 was rapidly supplemented (and popularized) by the 802.11b amendment in 1999, which increased the bit rate to 11 Mbit/s. Widespread adoption of 802.11 networks only occurred after the release of 802.11b which resulted in multiple interoperable products becoming available from multiple vendors. Consequently comparatively few networks were implemented on the 802.11-1997 standard.

Comparison chart

External references

*
*


Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • IEEE 802.11n-2009 — is an amendment to the IEEE 802.11 2007 wireless networking standard to improve network throughput over the two previous standards 802.11a and 802.11g with a significant increase in the maximum net data rate from 54 Mbit/s to 600 Mbit/s (slightly …   Wikipedia

  • IEEE 802.11n — is a proposed amendment to the IEEE 802.11 2007 wireless networking standard to significantly improve network throughput over previous standards, such as 802.11b and 802.11g, with a significant increase in the maximum raw (PHY) data rate from 54… …   Wikipedia

  • IEEE 802.11e-2005 — or 802.11e is an approved amendment to the IEEE 802.11 standard that defines a set of Quality of Service enhancements for wireless LAN applications through modifications to the Media Access Control (MAC) layer. The standard is considered of… …   Wikipedia

  • IEEE 802.11 — is a set of standards for wireless local area network (WLAN) computer communication, developed by the IEEE LAN/MAN Standards Committee (IEEE 802) in the 5 GHz and 2.4 GHz public spectrum bands.General descriptionThe 802.11 family includes over… …   Wikipedia

  • IEEE 802.11g-2003 — or 802.11g, is an amendment to the IEEE 802.11 specification that extended throughput to up to 54 Mbit/s using the same 2.4 GHz band as 802.11b. This specification under the marketing name of Wi Fi has been implemented all over the world. The 802 …   Wikipedia

  • IEEE 802.11 — El estándar IEEE 802.11 define el uso de los dos niveles inferiores de la arquitectura OSI (capas física y de enlace de datos), especificando sus normas de funcionamiento en una WLAN. Los protocolos de la rama 802.x definen la tecnología de redes …   Wikipedia Español

  • 802.1w — IEEE 802.1w is a Rapid Spanning Tree Protocol (RSTP) that can be seen as an evolution of the 802.1 standard. In most cases, RSTP performs better than Cisco Systems proprietary extensions without any additional configuration. 802.1w is also… …   Wikipedia

  • IEEE 1394 — Firewire redirects here. For other uses, see Firewire (disambiguation). IEEE 1394 Interface Type Serial Production history Designer …   Wikipedia

  • IEEE 1394 interface — Infobox Computer Hardware Bus name = IEEE 1394 interface invent date = 1995 invent name = Apple super name = super date = width = 1 numdev = 63 speed = 400–3200 Mbit/s style = s hotplug = Yes external = YesThe IEEE 1394 interface is a serial bus… …   Wikipedia

  • IEEE 1284 — For a history of the Centronics interface, see Centronics. IEEE 1284 is a standard that defines bi directional parallel communications between computers and other devices. An IEEE 1284 36 pin male Centronics printer cable connection. Contents …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”