Current WLAN Standards

The Institute of Electrical and Electronics Engineers (IEEE) 802.11b specifi cation is

802.11a operates in the 5-GHz waveband. Because they operate in different frequencies,

802.11b and 802.11a are incompatible. This means organizations that have already

deployed 802.11b networks, but want the faster speeds available through 802.11a, will

either have to build a new WLAN alongside the existing one or purchase hardware

that allows for both types of wireless cards to coexist. Several manufacturers currently

provide, or are planning to release, dual-mode access points, which can hold both 802.11a

and 802.11b cards. The power output of 802.11a is restricted, and the range tapers off

more quickly than in 802.11b.

At present, 802.11a experiences few of the signal interference and congestion problems

occasionally experienced by 802.11b users, although this may change now that license

restrictions on the 5-GHz frequency band have been lifted and use increases. We can

expect to see an increase in dual-platform access points to ensure compatibility between

equipment.

IEEE 802.11b

This type of equipment is most common for establishing a WLAN in business. Not all

802.11b equipment is compatible, so the Wi-Fi compatibility mark has been developed.

A Wi-Fi mark indicates compatibility between 802.11b products from different

manufacturers. 802.11b equipment that is not Wi-Fi branded should be treated with

caution. The 802.11b standard operates in the 2.4-GHz spectrum and has a nominal data

transfer rate of 11 Mbps; however, in practice, the data transmission rate is approximately

4 to 7 Mbps, around one-tenth the speed of a current wired LAN. This is still adequate for

accessing most data or applications, including Internet access, but would be insuffi cient

for multimedia applications or for instances when a large number of simultaneous users

want to access data in a single WLAN. Some manufacturers are producing 802.11b

solutions with additional functionality that offers throughput at 22 Mbps speed. It is

unclear if this type of equipment will be compatible across vendors.

IEEE 802.11a

the most common standard for WLANs. 802.11a has recently been cleared to operate

without a license in the 5-GHz frequency range. Several other standards are still under

development, including 802.11g, 802.11h, and Ultra Wideband (UWB).