IEEE 802.11 (legacy mode)
Encyclopedia
IEEE 802.11 — 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.
s 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.
IEEE 802.11
IEEE 802.11 is a set of standards for implementing wireless local area network computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are created and maintained by the IEEE LAN/MAN Standards Committee . The base version of the standard IEEE 802.11-2007 has had subsequent...
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 rateData signaling rate
In telecommunication, data signaling rate , also known as gross bit rate, is the aggregate rate at which data pass a point in the transmission path of a data transmission system.Notes:#The DSR is usually expressed in bits per second....
s of 1 and 2 megabits per second (Mbit/s) to be transmitted via infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
(IR) signals or by either frequency hopping or direct-sequence spread spectrum (DSSS)
Direct-sequence spread spectrum
In telecommunications, direct-sequence spread spectrum is a modulation technique. As with other spread spectrum technologies, the transmitted signal takes up more bandwidth than the information signal that is being modulated. The name 'spread spectrum' comes from the fact that the carrier signals...
in the Industrial Scientific Medical frequency band
ISM band
The industrial, scientific and medical radio bands are radio bands reserved internationally for the use of radio frequency energy for industrial, scientific and medical purposes other than communications....
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
Carrier Sense Multiple Access
Carrier Sense Multiple Access is a probabilistic Media Access Control protocol in which a node verifies the absence of other traffic before transmitting on a shared transmission medium, such as an electrical bus, or a band of the electromagnetic spectrum."Carrier Sense" describes the fact that a...
with collision avoidance
Collision avoidance
In spaceflight, collision avoidance is the process of preventing a spacecraft from colliding with any other vehicle or object.-Launch Windows:Collision avoidance, or COLA is a concern during spaceflight launch windows...
(CSMA/CA
Carrier sense multiple access with collision avoidance
Carrier sense multiple access with collision avoidance , in computer networking, is a wireless network multiple access method in which:*a carrier sensing scheme is used....
) 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
Alvarion
Alvarion Ltd. , is a 4G communications company. The company manufactures and exports a range of network solutions, including WiMAX, IEEE, PtMP, TD-LTE and WiFi to service providers and enterprises covering a variety of industries such as mobile broadband, residential and business broadband,...
(PRO.11 and BreezeAccess-II), BreezeCom, Digital / Cabletron (RoamAbout) , Lucent, Netwave Technologies (AirSurfer Plus and AirSurfer Pro), Symbol Technologies
Symbol Technologies
Symbol Technologies is a manufacturer and worldwide supplier of mobile data capture and delivery equipment. The company specializes in barcode scanners, mobile computers, RFID systems and Wireless LAN infrastructure. Symbol Technologies is a wholly owned subsidiary of Motorola, and headquartered in...
(Spectrum24), and Proxim Wireless
Proxim Wireless
Proxim Wireless Corporation , is a San Jose, California-based company that builds scalable broadband wireless networking systems for communities, enterprises, governments, and service providers. It claims to offer WLAN, mesh, point-to-multipoint and point-to-point products through a global channel...
(OpenAir
OpenAir (communications standard)
OpenAir was an early wireless standard promoted by the Wireless LAN Interoperability Forum implemented predominantly by Proxim Wireless devices. It operates in the 2.4GHz band and uses frequency hopping with 0.8 and 1.6 Mb/s bit rates via 2 or 4 frequency-shift keying modulation....
and Rangelan2
Rangelan2
RangeLAN2 was a broad family of wireless devices developed by Proxim Wireless, and is a trademark of that company. It also refers to the RangeLAN2 wireless communications protocol, used by these devices, but the protocol was officially renamed OpenAir...
). 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.