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WiFi & Spread Spectrum

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Wireless local area network (LAN) systems are based on a variety of technologies, but the most widely produced systems belong to the 802.11 family of standards established by the Institute of Electrical and Electronics Engineers (IEEE). Wireless LAN systems that comply with IEEE 802.11b, also known as WiFi, are low-power systems that use the unlicensed bands in the 2.4GHz spectrum to support data transfer at rates of 11 Mbps, 5.5 Mbps, 2 Mbps and 1 Mbps (more about data transfer rates ). Other standards within the 802.11 family include 802.11a, which uses the 5 GHz band and supports data rates up to 54 Mbps; and 802.11g, approved in June 2003, which operates in the same bands as 802.11b but supports data rates up to 54 Mbps. The maximum data transfer rate decreases as the distance between the nodes increases.

Wireless LAN systems can be configured for two largely distinct applications: (1) replacing the wired connections between computers on a local area network (LAN), or (2) bridging or routing between LANs in different buildings through point-to-point or point-to-multipoint links.

802.11b systems are required by regulators to have low output power so as to limit the range and reduce potentially harmful interference with other systems that have priority in the designated frequency bands. The result is that the input power for 802.11b systems is also low – less than two Watts for most PC cards, and typically 4-7 W for access points.

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