IEEE 802.11 WLAN Standards

IEEE 802.11 is a set of standards for wireless network to provide wireless devices with a communication in the 2.4, 3.6 and 5 GHz frequency bands. They are originally developed and maintained by the IEEE (Institute of Electrical and Electronics Engineers) LAN/MAN Standards Committee (LMSC).

The first standard was created by IEEE in 1997 and had been named as 802.11. It uses unregulated radio signaling frequency (2.4 GHz) but only supported up to 2 Mbps maximum network bandwidth. Specific physical layers that enabled three faster radio layers had been defined by subsequent amendments of IEEE 802.11:
802.11b
802.11b was created based on the specification of original 802.11 in July 1999, and it support network bandwidth up to 11 Mbps.
802.11b uses unregulated radio signaling frequency (2.4 GHz) as same as the original 802.11 standard. It provides 3 radio channels. By using this frequency, the manufacturing costs could be lower down. Because of unregulated signal, 802.11b could incur interference from other appliances using the same 2.4 GHz range, such as microwave ovens, cordless phones. However, the interferences can be avoided by installing 802.11b a reasonable distance from other appliances.

• Pros of 802.11b – cost is cheapest; signal range is very good and not easily to be obstructed.
• Cons of 802.11b – maximum speed is still slower; home appliances may interfere on the unregulated frequency band.

802.11a
A second extension to the original 802.11 standard was created and called 802.11a. Due to its higher cost, 802.11a is usually found on business networks whereas 802.11b better serves the home market.
802.11a supports up to 54 Mbps network bandwidth and provides 8 radio channels in the 5 GHz frequency band. Because of this higher frequency, the range of 802.11a networks is also shortened. In addition, the higher frequency also makes the signal of 802.11a to have more difficulty in penetrating walls and other obstacles.

• Pros of 802.11a – faster maximum speed; regulated frequencies can get rid of signal interference from other home appliances.
• Cons of 802.11a – expensive in cost; shorter range signal and more easily to be obstructed.

802.11g
802.11g was created to combine the best of both 802.11a and 802.11b and supports network bandwidth up to 54 Mbps. It uses the 2.4 GHz frequency for wider range. 802.11g is backwards compatible with 802.11b, which means the access point of 802.11g will just work fine with all the wireless network adapters of 802.11b, and vice versa.

• Pros of 802.11g – fast maximum speed; signal range is very good and not easily to be obstructed.
• Cons of 802.11g – cost is higher than 802.11b; other appliances may interfere on the unregulated.

802.11n
802.11n is the newest IEEE standard in the 802.11 family. It improves on 802.11g in the amount of bandwidth by using multiple wireless signals and antennas instead of one. This is a technology called MIMO (multiple-input multiple-output). It will also operate on the 2.4 GHz band. Presently the development of this standard is still in progress. But when this standard is finalized, 802.11n connections will be able to support data rates up to 100 Mbps. 802.11n also offers better range over earlier 802.11 standards due to its increased signal intensity.

• Pros of 802.11g –best signal range and fastest in maximum speed; more ability to resist signal interference from other sources.
• Cons of 802.11g –cost is higher than 802.11g; the use of multiple signals may massively be interfered by nearby 802.11b or 802.11g based networks.