Computerworld - With wireless Ethernet specifications, the data rate you see on the box isn't the throughput you get. "The efficiencies have been about 50% or 60%" due to network protocol overhead and environmental factors, says Ray Martino, vice president of network products at Holtsville, N.Y.-based Symbol Technologies Inc.
That means a 54M bit/sec. 802.11a connection would deliver, at best, about 26M bit/sec. of throughput, vs. about 5M bit/sec. for 802.11b. While tests show 802.11a to be about five times faster than 802.11b at close proximity, its throughput curve drops more sharply as distance increases. According to a white paper by Sunnyvale, Calif.-based Atheros Communications Inc., throughput drops to 22.5M bit/ sec. at 65 ft. and to 15M bit/sec. at 100 ft. That's still two times faster than 802.11b, but achieving higher data rates will require placing more access points for a given coverage area.
In addition, lab tests conducted by Network World magazine and others cite throughput rates substantially lower that those provided by vendors, ranging from about 12M bit/sec. to 23M bit/sec. And the higher numbers were posted by devices operating in proprietary "turbo" modes. Vendors and analysts anticipate improvements as products mature.
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