WLANs and PANs (2)

• IEEE 802.11a Standard. IEEE 802.11a standardizes wireless devices operating at 5 GHz. “The specification for 5GHz was developed prior to the changes in 802.11b at 2.4GHz, and hence the odd numbering sequence. Bandwidth will scale from 6 to 54 Mbps. Future implementations of 100 Mbps are still being considered. 802.11a implements dynamic frequency selection, transmit power control and inter-access point protocol, features found in WAN cellular systems” (Gartner Group). Transmit power control enables a wide variety of cell sizes, permitting some applications to enjoy greater frequency reuse (which is important in high-density applications, such as stock exchanges). 801.11a employs between 40 mW and 200 mW of transmit power, compared with the 100 mW nominally used for 2.4 GHz. Despite technical enhancements that attempt to ensure transmission characteristics similar to those for 2.4 GHz, 50 percent more access points will be required to maintain a comparable footprint to a 2.4 GHz installation (0.6 probability).
• IEEE 802.11g Standard. The 802.11g working group is examining an upgrade to the 802.11b standard operating at 2.4 GHz in order to offer higher-speed services. Two alternatives are: (1) use of direct sequence to 20+ Mbps, and (2) use of orthogonal frequency division multiplexing (OFDM) to 54 Mbps. The 802.11g committee is split on which direction to take. Because of the emergence of 802.11a and the fact that a direct sequence improvement would permit users to upgrade, the first option will likely be the appropriate choice (Gartner Group).

Taken From : Enterprise Guide to Gaining Business Value from Mobile Technologies

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