Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
specifications.
The 802.11 family define a Wireless Local Area Network [WLAN]
using the Ethernet protocol, using Carrier Sense, Multiple Access with
Collision Avoidance (CSMA/CA). The 802.11 wireless LAN
standards provide a number of channels within each frequency band, and a
number of data rates. The highest data rate is listed below. The 802.11
standard also specified infrared [IR], but I think the IrDA standard was more widely used.
Frequency-Hopping Spread Spectrum [FHSS], or direct sequence Sprad
Spectrum [DSSS] are specified. 802.11 specifies a LAN with a minimum of
two stations.
802.11g transmit at a frequency of 2.4 GHz with data rates of
54Mbps [OFDM, DSSS]. IEEE 802.11b and 802.11g are compatible, devices can
coexist in the same network. IEEE 802.11g was released in 2003 and is
backward compatible with the 'b' version. 802.11g operates on the same
frequency bands as 802.11b, 2.4GHz to 2.497GHz. Using CCK [Complementary
Code Keying] modulation, 802.11g operates at data rates of 1, 2, 5.5, and
11Mbps. While OFDM [Orthogonal Frequency Division Multiplexing]
modulation allows data rates of 6, 9, 12, 24, 36, 48 and 54Mbps
[bits-per-second]. However the maximum data drops as the distance is
increased.
The data rate for 802.11g is equal to that of 802.11a, but much greater
than that of 802.11b which only operates at 12Mbps. The transmission
distance [range] is slightly better than 802.11a [25 feet], and about
equal to the range of 802.11b [at 12Mbps and under]. The IEEE802.11g is
an improvement over 802.11b and replaced that standard in the market
place.
However, the IEEE802.11g standard may soon fall as the wireless network
of choice once the 802.11n specification is released. Wireless products
that conform to the draft standard for wireless-n are already available.
Many advise against purchasing pre-released [draft] 802.11n devices
because of potential compatibility issues.
802.11a [Wi-Fi] transmit at a frequency of 5 GHz with data
rates of 54 Mbps using Orthogonal Frequency Division Multiplexing
[OFDM].
802.11b [Wi-Fi]
transmit at a frequency of 2.4 GHz with data rates of 11 Mbps using
direct sequence spread spectrum modulation [DSSS].
802.11h transmit at a frequency of 5GHz with data rates of
100Mbps. IEEE 802.11b and 802.11g are compatible so devices can coexist
in the same network
802.11n transmit at a
frequency of 2.4GHz or 5 GHz with data rates of 600Mbps. IEEE 802.11b and
802.11g are compatible, devices can coexist in the same network.
The 2.4GHz band is part of the ISM [Industrial, Scientific, and Medical] license-free radio bands [see below]. Both 802.11 and Bluetooth operate with in the band. Additional frequencies of the ISM band include the 900MHz band, and 5.8GHz band
Chart of US Frequency Allocations *.pdf {NTIA}
Companies which manufacture Wireless ICs are listed on the RF component manufacturers page
For reference the IEEE 802.xx Family of standards are listed below:
IEEE 802.1 Higher layer LAN protocols
IEEE 802.2 Logical link control
IEEE 802.3 Ethernet.
IEEE 802.4 Token bus
IEEE 802.5 Token Ring, used FDDI.
IEEE 802.6 metropolitan area networks
IEEE 802.7 broadband
IEEE 802.8 fiber optic
IEEE 802.9 isochronous LAN
IEEE 802.10 Security
IEEE 802.11 Wireless LAN [ISO/IEC 8802-11]
IEEE 802.12 demand priority
IEEE 802.13 (not used)
IEEE 802.14 Cable modems (Not active)
IEEE 802.15 Wireless PAN [Personal Area Networks]
IEEE 802.16 Broadband wireless access
IEEE 802.17 Resilient packet ring
IEEE 802.20 Mobile Broadband Wireless Access
[Industrial, Scientific, and Medical], license-free radio bands
6780 kHz ±15.0 kHz
13560 kHz ±17.0 kHz
27120 kHz ±163.0 kHz
40.68 MHz ±20.0 kHz
915 MHz ±13.0 MHz
2450 MHz ±50.0 MHz
5800 MHz ±75.0 MHz
24.125 GHz ±125.0 MHz
61.25 GHz ±250.0 MHz
122.5 GHz ±500.0 MHz
245 GHz ±1.0 GHz
BWA: Broadband wireless access
LOS: Line-of-Sight
NLOS: Non-Line-of-Sight
WEP: Wired Equivalent Privacy
WPA: Wi-Fi Protected Access
Electronic Design Key words: IEEE 802.11g, Ad hoc network, Air, Radio, Wireless Ethernet, 802.11, Wireless Local Area Networks, WEP, OFDM, AES, Wireless LANs, Wireless Personal Area Networks, Wireless PANs, WiMax, Wireless Metropolitan Area Networks, Wireless MANs, Mobile, 802.11g, 802.15, 802.16, Metropolitan area network, MAN, CSMA/CD, Independent Basic Service Set, Station, Mobile, Portable.
|
|
|||||||
| Home | |||||||
|
|
|||||||
|
|
|
|
|
|
|
|
|
| Distributors | Components | Equipment | Software | Standards | Buses | Design | Reference |