802.11: Alphabet soup

Wi-Fi's rise through the corporate structure has been meteoric. The technology has quickly progressed from an alternative wireless method to the de facto means to transfer data wirelessly within a LAN. However, before the mass adoption of Wi-Fi in the enterprise occurs, the advantages and disadvantages of 802.11a and the emerging 802.11g must be understood.

The two real choices are the existing 802.11a standard and the emerging 802.11g standard. 802.11b exists, yet doesn't offer the throughput required to meet the needs of an enterprise.

The first 802.11 specification to make the scene is 802.11a. It offers maximum data rates at 54Mbps and operates in the 5GHz frequency range. Because of the higher frequency used, 802.11a works best in the relatively short range of 50 meters to 70 meters. Yet using a higher band also means enterprises can deploy as many as 12 access points without them interfering with one another. This means many more users can be served.

Similarly, the 802.11g specification runs at 54Mbps, but therein the similarities stop. 802.11g, which will likely be ratified in June or August by the IEEE, operates in the 2.4GHz spectrum using a technique called OFMD (orthogonal frequency division multiplexing) that squeezes more bits on to a radio wave; resulting in 54Mbps throughput at a lower cost than 802.11a. However, the 2.4Ghz band or ISM band is a shared frequency used also by cordless phones, microwaves, and a slew of equipment most of which is often found in hospitals. This means 802.11g is likely to experience much more interference than 802.11a. Also the use of the ISM band means 802.11g is limited to a band that is only 30MHz wide, thus limiting the number of access points that can be deployed to three.

Recall that 802.11g is mandated to be backward-compatible with the slower 802.11b standard, thus offering investment protection to those enterprises that have deployed 802.11b equipment that offers a maximum throughput of 11Mbps.

If and when the 802.11g is ratified later this year, the Wi-Fi Alliance will quickly begin qualifying 802.11g products and certifying them as 802.11g-compliant said Brian Grimm, a spokesman for the Wi-Fi alliance.

Dennis Anderson, a senior software engineer in IBM Corp.'s pervasive computing division, said IBM will support 802.11g upon ratification and that the choice of which one depends on needs.

Morikazu Sano, vice president of Buffalo Technology (USA) Inc.'s networking division, agreed. He believed 802.11g will be popular in less dense places and for consumer users. 802.11a he said will remain the domain of enterprises with cramped spaces, and enterprises that want something built today.

Either way, the chipset manufactures are happy. Broadcom Corp. and Intersil Corp. both make 802.11a and 802.11g chipsets and both are at work on a dual-band chipset that supports both.

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