Field Guide to Wireless LANs for Administrators and Power Users, A

Summary of IEEE 802.11 PHYs

The naming of the various PHYs defined in the context of IEEE 802.11 is not as descriptive as one might hope. The original RF-based PHYs were named Frequency Hopping Spread Spectrum (FHSS) and Direct Sequence Spread Spectrum (DSSS). In addition to these RF-based PHYs, the IEEE 802.11-1999 specification also specified a diffuse infrared PHY. All of those PHYs operate at either 1 or 2 Mbps. There was no specific “marketing” name for the 1 and 2 Mbps PHYs, other than “IEEE 802.11.”

IEEE 802.11a

The IEEE 802.11a-1999 standard specifies a “High-Speed Physical Layer in the 5 GHz Band.” To quote the standard, the following describes the actual attributes of IEEE 802.11a PHYs:

• The radio frequency LAN system is initially aimed ...