IEEE 802.11b-1999
Encyclopedia
IEEE 802.11b-1999 or 802.11b, is an amendment to the IEEE 802.11
specification that extended throughput up to 11 Mbit/s using the same 2.4 GHz
band. This specification under the marketing name of Wi-Fi
has been implemented all over the world. The amendment has been incorporated into the published IEEE 802.11-2007 standard.
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, 802.11g and 802.11n versions to provide wireless connectivity in the home, office and some commercial establishments.
media access method defined in the original standard. Due to the CSMA/CA protocol overhead, in practice the maximum 802.11b throughput that an application can achieve is about 5.9 Mbit/s using TCP
and 7.1 Mbit/s using UDP
.
802.11b products appeared on the market in mid-1999, since 802.11b is a direct extension of the DSSS
(Direct-sequence spread spectrum) modulation technique defined in the original standard. Technically, the 802.11b standard uses Complementary code keying
(CCK) as its modulation technique. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones. Interference issues and user density problems within the 2.4 GHz band have become a major concern and frustration for users.
configuration, wherein an access point
communicates via an omnidirectional antenna
with one or more nomadic or mobile clients that are located in a coverage area around the access point. Typical indoor range is 30 m (100 ft) at 11 Mbit/s and 90 m (300 ft) at 1 Mbit/s. The overall bandwidth is dynamically demand shared across all the users on a channel. With high-gain external antennas, the protocol can also be used in fixed point-to-point arrangements, typically at ranges up to 8 kilometres (5 mi) although some report success at ranges up to 80–120 km (50–75 miles) where line of sight
can be established. This is usually done in place of costly leased line
s or very cumbersome microwave
communications equipment. Designers of such installations who wish to remain within the law must however be careful about legal limitations on effective radiated power
.
802.11b cards can operate at 11 Mbit/s, but will scale back to 5.5, then 2, then 1 Mbit/s (also known as Adaptive Rate Selection), if signal quality becomes an issue.
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...
specification that extended throughput up to 11 Mbit/s using the same 2.4 GHz
GHZ
GHZ or GHz may refer to:# Gigahertz .# Greenberger-Horne-Zeilinger state — a quantum entanglement of three particles.# Galactic Habitable Zone — the region of a galaxy that is favorable to the formation of life....
band. This specification under the marketing name of Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
has been implemented all over the world. The amendment has been incorporated into the published IEEE 802.11-2007 standard.
802.11 is a set of IEEE standards that govern wireless networking transmission methods. They are commonly used today in their 802.11a, 802.11b, 802.11g and 802.11n versions to provide wireless connectivity in the home, office and some commercial establishments.
Description
802.11b has a maximum raw data rate of 11 Mbit/s and uses the same CSMA/CACarrier 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....
media access method defined in the original standard. Due to the CSMA/CA protocol overhead, in practice the maximum 802.11b throughput that an application can achieve is about 5.9 Mbit/s using TCP
Transmission Control Protocol
The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...
and 7.1 Mbit/s using UDP
User Datagram Protocol
The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
.
802.11b products appeared on the market in mid-1999, since 802.11b is a direct extension of the 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...
(Direct-sequence spread spectrum) modulation technique defined in the original standard. Technically, the 802.11b standard uses Complementary code keying
Complementary code keying
Complementary Code Keying is a modulation scheme used with wireless networks that employ the IEEE 802.11b specification. In 1999, CCK was adopted to supplement the Barker code in wireless digital networks to achieve data rate higher than 2 Mbit/s at the expense of shorter distance...
(CCK) as its modulation technique. The dramatic increase in throughput of 802.11b (compared to the original standard) along with simultaneous substantial price reductions led to the rapid acceptance of 802.11b as the definitive wireless LAN technology.
802.11b devices suffer interference from other products operating in the 2.4 GHz band. Devices operating in the 2.4 GHz range include: microwave ovens, Bluetooth devices, baby monitors and cordless telephones. Interference issues and user density problems within the 2.4 GHz band have become a major concern and frustration for users.
Range
802.11b is used in a point-to-multipointPoint-to-multipoint
Point-to-multipoint communication is a term that is used in the telecommunications field which refers to communication which is accomplished via a specific and distinct type of one-to-many connection, providing multiple paths from a single location to multiple locations.Point-to-multipoint is often...
configuration, wherein an access point
Wireless access point
In computer networking, a wireless access point is a device that allows wireless devices to connect to a wired network using Wi-Fi, Bluetooth or related standards...
communicates via an omnidirectional antenna
Omnidirectional antenna
In radio communication, an omnidirectional antenna is an antenna which radiates radio wave power uniformly in all directions in one plane, with the radiated power decreasing with elevation angle above or below the plane, dropping to zero on the antenna's axis. This radiation pattern is often...
with one or more nomadic or mobile clients that are located in a coverage area around the access point. Typical indoor range is 30 m (100 ft) at 11 Mbit/s and 90 m (300 ft) at 1 Mbit/s. The overall bandwidth is dynamically demand shared across all the users on a channel. With high-gain external antennas, the protocol can also be used in fixed point-to-point arrangements, typically at ranges up to 8 kilometres (5 mi) although some report success at ranges up to 80–120 km (50–75 miles) where line of sight
Line-of-sight propagation
Line-of-sight propagation refers to electro-magnetic radiation or acoustic wave propagation. Electromagnetic transmission includes light emissions traveling in a straight line...
can be established. This is usually done in place of costly leased line
Leased line
A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy...
s or very cumbersome microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
communications equipment. Designers of such installations who wish to remain within the law must however be careful about legal limitations on effective radiated power
Effective radiated power
In radio telecommunications, effective radiated power or equivalent radiated power is a standardized theoretical measurement of radio frequency energy using the SI unit watts, and is determined by subtracting system losses and adding system gains...
.
802.11b cards can operate at 11 Mbit/s, but will scale back to 5.5, then 2, then 1 Mbit/s (also known as Adaptive Rate Selection), if signal quality becomes an issue.
Channels and Frequencies
| Channel | Center Frequency | Frequency delta | Channel Width | Overlaps Channels |
|---|---|---|---|---|
| 1 | 2.412 GHz | 5 MHz | 2.401–2.423 GHz | 2 |
| 2 | 2.417 GHz | 5 MHz | 2.406–2.428 GHz | 1,3 |
| 3 | 2.422 GHz | 5 MHz | 2.411–2.433 GHz | 2,4 |
| 4 | 2.427 GHz | 5 MHz | 2.416–2.438 GHz | 3,5 |
| 5 | 2.432 GHz | 5 MHz | 2.421–2.443 GHz | 4,6 |
| 6 | 2.437 GHz | 5 MHz | 2.426–2.448 GHz | 5,7 |
| 7 | 2.442 GHz | 5 MHz | 2.431–2.453 GHz | 6,8 |
| 8 | 2.447 GHz | 5 MHz | 2.436–2.458 GHz | 7,9 |
| 9 | 2.452 GHz | 5 MHz | 2.441–2.463 GHz | 8,10 |
| 10 | 2.457 GHz | 5 MHz | 2.446–2.468 GHz | 9,11 |
| 11 | 2.462 GHz | 5 MHz | 2.451–2.473 GHz | 10,12 |
| 12 | 2.467 GHz | 5 MHz | 2.456–2.478 GHz | 11,13 |
| 13 | 2.472 GHz | 5 MHz | 2.461–2.483 GHz | 12 |
| 14 | 2.484 GHz | 12 MHz | 2.473–2.495 GHz |
- Note: Channel 14 is only allowed in Japan, Channels 12 & 13 are allowed in most parts of the world, except the USA, where only Channels 1 to 11 are legal to use. More information can be found in the List of WLAN channels.
See also
- IEEE 802.11IEEE 802.11IEEE 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...
- IEEE 802.11g-2003IEEE 802.11g-2003IEEE 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...
- Wi-FiWi-FiWi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
- List of WLAN channels