Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
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 Spread 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
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] transmits at a frequency of 5 GHz with data
rates of 54 Mbps using Orthogonal Frequency Division Multiplexing
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 transmits 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. Refer to list below for possible frequency bands.
Companies which manufacture Wireless ICs:
RF component manufacturers page
IEEE 802.11 Wireless LAN [ISO/IEC 8802-11]
This list does not represent all the different documents in the IEEE 802.xx Family of standards.
The revisions listed above show that new version have been coming out [with a new letter designation].
The differences between the standard are the encoding methods, but in some cases the frequency range also changes.
License-free ISM 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
Each of these bands all have very low ranges, or power requirements.
BWA: Broadband wireless access
MAC: Medium Access Control
PHY: Physical Layer
WEP: Wired equivalent Privacy
WPA: Wi-Fi Protected Access