IEEE 802.11g-2003
Encyclopedia
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 802.11g protocol is now Clause 19 of 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.
s. It works in the 2.4 GHz band (like 802.11b) but operates at a maximum raw data rate of 54 Mbit/s, or about 19 Mbit/s net throughput
(identical to 802.11a core, except for some additional legacy overhead for backward compatibility). 802.11g hardware is fully backwards compatible with 802.11b hardware. Details of making b and g work well together occupied much of the lingering technical process. In an 802.11g network, however, the presence of a legacy 802.11b participant will significantly reduce the speed of the overall 802.11g network.
The modulation scheme used in 802.11g is orthogonal frequency-division multiplexing
(OFDM) copied from 802.11a with data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbit/s, and reverts to CCK
(like the 802.11b standard) for 5.5 and 11 Mbit/s and DBPSK
/DQPSK
+DSSS for 1 and 2 Mbit/s. Even though 802.11g operates in the same frequency band as 802.11b, it can achieve higher data rates because of its heritage to 802.11a.
Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, Bluetooth
devices, baby monitors and digital cordless telephones, which can lead to interference issues. Additionally, the success of the standard has caused usage/density problems related to crowding in urban areas. To prevent interference, there are only three non-overlapping usable channels in the U.S. and other countries with similar regulations (channels 1, 6, 11, with 25 MHz separation), and four in Europe (channels 1, 5, 9, 13, with only 20 MHz separation). Even with such separation, some interference due to side lobe
s exists, though it is considerably weaker.
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 to up to 54 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 as 802.11b. 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 802.11g protocol is now Clause 19 of 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.
Descriptions
802.11g is the third modulation standard for wireless LANWireless LAN
A wireless local area network links two or more devices using some wireless distribution method , and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network...
s. It works in the 2.4 GHz band (like 802.11b) but operates at a maximum raw data rate of 54 Mbit/s, or about 19 Mbit/s net throughput
Throughput
In communication networks, such as Ethernet or packet radio, throughput or network throughput is the average rate of successful message delivery over a communication channel. This data may be delivered over a physical or logical link, or pass through a certain network node...
(identical to 802.11a core, except for some additional legacy overhead for backward compatibility). 802.11g hardware is fully backwards compatible with 802.11b hardware. Details of making b and g work well together occupied much of the lingering technical process. In an 802.11g network, however, the presence of a legacy 802.11b participant will significantly reduce the speed of the overall 802.11g network.
The modulation scheme used in 802.11g is orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing
Orthogonal frequency-division multiplexing is a method of encoding digital data on multiple carrier frequencies. OFDM has developed into a popular scheme for wideband digital communication, whether wireless or over copper wires, used in applications such as digital television and audio...
(OFDM) copied from 802.11a with data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbit/s, and reverts to CCK
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...
(like the 802.11b standard) for 5.5 and 11 Mbit/s and DBPSK
Phase-shift keying
Phase-shift keying is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal ....
/DQPSK
Phase-shift keying
Phase-shift keying is a digital modulation scheme that conveys data by changing, or modulating, the phase of a reference signal ....
+DSSS for 1 and 2 Mbit/s. Even though 802.11g operates in the same frequency band as 802.11b, it can achieve higher data rates because of its heritage to 802.11a.
Adoption
The then-proposed 802.11g standard was rapidly adopted by consumers starting in January 2003, well before ratification, due to the desire for higher speeds and reductions in manufacturing costs. By summer 2003, most dual-band 802.11a/b products became dual-band/tri-mode, supporting a and b/g in a single mobile adapter card or access point.Despite its major acceptance, 802.11g suffers from the same interference as 802.11b in the already crowded 2.4 GHz range. Devices operating in this range include microwave ovens, Bluetooth
Bluetooth
Bluetooth is a proprietary open wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security...
devices, baby monitors and digital cordless telephones, which can lead to interference issues. Additionally, the success of the standard has caused usage/density problems related to crowding in urban areas. To prevent interference, there are only three non-overlapping usable channels in the U.S. and other countries with similar regulations (channels 1, 6, 11, with 25 MHz separation), and four in Europe (channels 1, 5, 9, 13, with only 20 MHz separation). Even with such separation, some interference due to side lobe
Side lobe
In antenna engineering, side lobes or sidelobes are the lobes of the far field radiation pattern that are not the main lobe....
s exists, though it is considerably weaker.
Channels and Frequencies
| Channel | Center Frequency | Channel Width | Overlaps Channels |
|---|---|---|---|
| 1 | 2.412 GHz | 2.401 GHz - 2.423 GHz | 2,3,4,5 |
| 2 | 2.417 GHz | 2.406 GHz - 2.428 GHz | 1,3,4,5,6 |
| 3 | 2.422 GHz | 2.411 GHz - 2.433 GHz | 1,2,4,5,6,7 |
| 4 | 2.427 GHz | 2.416 GHz - 2.438 GHz | 1,2,3,5,6,7,8 |
| 5 | 2.432 GHz | 2.421 GHz - 2.443 GHz | 1,2,3,4,6,7,8,9 |
| 6 | 2.437 GHz | 2.426 GHz - 2.448 GHz | 2,3,4,5,7,8,9,10 |
| 7 | 2.442 GHz | 2.431 GHz - 2.453 GHz | 3,4,5,6,8,9,10,11 |
| 8 | 2.447 GHz | 2.436 GHz - 2.458 GHz | 4,5,6,7,9,10,11,12 |
| 9 | 2.452 GHz | 2.441 GHz - 2.463 GHz | 5,6,7,8,10,11,12,13 |
| 10 | 2.457 GHz | 2.446 GHz - 2.468 GHz | 6,7,8,9,11,12,13 |
| 11 | 2.462 GHz | 2.451 GHz - 2.473 GHz | 7,8,9,10,12,13 |
| 12 | 2.467 GHz | 2.456 GHz - 2.478 GHz | 8,9,10,11,13 |
| 13 | 2.472 GHz | 2.461 GHz - 2.483 GHz | 9,10,11,12 |
- Note: Not all channels are legal to use in all countries.
See also
- List of WLAN channels
- OFDM system comparison table
- Spectral efficiency comparison table
- 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...