Achieving speeds previously relegated to wired networks, the IEEE 802.11a wireless local area network (WLAN) standard promises to dramatically alter the landscape of wireless connectivity in the enterprise, home, and outdoor settings. Operating in the interference-free 5GHz band, the 802.11a standard allows speeds of up to 54Mbps in a local area. 802.11a achieves its performance by using Orthogonal Frequency Division Multiplexing (OFDM), error-correcting codes, and constellations ranging from BPSK to 64QAM, supporting in eight different data rates from 6Mbps to 54Mbps to optimize performance under a variety of conditions.

The 802.11 suite of networking protocols has been gaining wide acceptance in the last year as evidenced by the growing popularity of 11Mbps 802.11b systems (also know as WiFi). While 802.11a and 802.11b share the same Media Access Control (MAC), different physical layers allow 802.11a to achieve link rates of 5x those of 802.11b. Additionally 802.11a operates in the U-NII band - which occupies 300MHz of spectrum in the 5GHz band in the U.S., allowing 12 independent channels and avoids interference from other devices in 802.11b's 83.5MHz of spectrum in the 2.4GHz band.

Is 802.11a real? How well does it work?
While 802.11b hooked users on the notion of untethered computing in end of 1999, Atheros Communications is the first to market a volume production 802.11a chipset in Fall '01. The two chip all-CMOS solution delivers higher performance at a cost and power consumption comparable to the existing 802.11b solutions. Similar power consumption at higher data rates results in significantly reduced energy consumption for the transmission or reception of a given amount of information. Atheros' chipset also supports a "turbo" mode yielding 72Mbps operation.

Measured performance data demonstrates that Atheros' 5-GHz 802.11a systems obtain speeds 4-5 times greater than a popular 802.11b wireless LAN in a typical office environment. Coupled with more available spectrum, this results in greatly increased system capacity allowing increased per-user throughput or reduced cost of deployment.

OEB ComSoc Presentation: 802.11a Principles and Performance
The speaker will present the fundamentals of 802.11a network operation. He will then present the results of physical layer testing of Atheros 802.11a reference-design systems in a typical office environment and present its implications to enterprise deployment performance and cost. If you want to understand the future of wireless LANs today, be sure not to miss this meeting.

Jeffrey M. Gilbert, Manager of Advanced Technology at Atheros Communications, is lead architect of their next-generation wireless systems. Previously, he was the Director of Engineering at the Teratech Corporation, a startup developing highly-portable PC-based medical ultrasound imagers. Dr. Gilbert received a Ph.D. from the University of California Berkeley, M.Phil. from Cambridge University, and B.A. from Harvard College.

" 802.11a Wireless Networks: Principles and Performance" was presented by Dr. Jeffrey M. Gilbert of Atheros Communications.