Wireless LANs provide mobility. Who does not want to be able to carry a laptop to the conference room down the hall and still have complete network access without worrying about network cables? Manufacturing companies are even using wireless LANs to monitor shop floor machinery that is not traditionally accessible by network cabling. Increased mobility and accessibility improves communication, productivity, and efficiency. How much more productive could a team meeting be if all participants meeting in the conference room still had access to the network and the files relating to the project being discussed?
Wireless LANs can also provide a cost benefit. Installing and configuring wired communications can be costly, sometimes more than $200 per person. A wireless NIC currently costs around $150. When the person moves, the wireless network connection moves with him. You do not need to reconfigure any wire connections.
The increased mobility and cost-effectiveness make wireless LANs a popular alternative. Gartner Group predicts that wireless LAN revenue will total $487 million this year, and the value of installed wireless LANs will grow to $35.8 billion in 2004. Cahners In-Stat Group predicts that the wireless LAN market will grow 25 percent annually over the next few years, from $771 million in 2000 to $2.2 billion in 2004. Although these estimates are quite different, they share one common theme: A significant number of new wireless LANs will be deployed, and existing installations will be expanded. This growth will occur because increases in speed, decreases in price, and the adoption of a formal standard with broad industry support have all occurred in the past year.
In June 1997, the Institute of Electrical and Electronic Engineers (IEEE) finalized the initial standard for wireless LANs, IEEE 802.11. This standard specifies a 2.4GHz operating frequency with data rates of 1Mbps and 2Mbps. With this standard, you can choose between using frequency hopping or direct sequence, two incompatible forms of spread spectrum modulation. In late 1999, the IEEE published two supplements to the initial 802.11 standard: 802.11a and 802.11b. Like the initial standard, 802.11b operates in the 2.4GHz band, but data rates can be as high as 11Mbps, and only direct sequence modulation is specified.
The 802.11a standard specifies operation in the 5GHz band using orthogonal frequency-division multiplexing (OFDM), with data rates up to 54Mbps. Advantages of this standard include higher capacity and less RF interference than with other types of devices. Even though the 802.11a standard exists, there are few, if any, products on the market. They should be available later this year, though.
To complicate issues, Europe has developed the HiperLAN/2 standard, led by the European Telecommunications Standards Institute. (ETSI). HiperLAN/2 and 802.11a share some similarities—both use OFDM technology to achieve their data rates in the 5GHz range—but they are not interoperable.
802.11a and 802.11b operate in different frequencies, so there is little chance that they will be interoperable. They can coexist on one network, though, because there is no signal overlap. Some vendors claim that they will provide a dual-radio system with 802.11a and 802.11b in the future.
The rest of this article focuses on 802.11b wireless LANs because they comprise the current install base.