Update: Intersil promises to double 802.11g WLAN throughput

Computerworld - Intersil Corp. said it has developed a way to turbocharge 802.11g wireless LAN hardware operating in a mixed network with older 802.11b hardware, according to Joe Zyren, the company's director of strategic marketing.
Though 802.11g has a raw data rate of 54Mbit/sec., the final draft of the 802.11g standard approved May 15 by Institute of Electrical and Electronics Engineers Inc. provides for actual data rates of 10Mbit/sec. when 802.11g clients operate in a mixed network with 802.11b clients (see story). Both standards operate in the same 2.4-GHz frequency band
Zyren said Milipitas, Calif.-based Intersil has developed a nonproprietary firmware upgrade called Nitro that will boost throughput of 802.11g hardware in a mixed network to 20Mbit/sec. That would be the same speed offered in a pure 802.11g network. He said Nitro, which Intersil would like to see incorporated in the IEEE 802.11e standard that governs WLAN quality of service, boosts throughput by allowing 802.11g devices to transmit six times as many packets as normal before having to transmit a "Clear To Send Signal" command to 802.11b clients in the network.
Sheung Li, a product marketing manager at Atheros Communications Inc. in Sunnyvale, Calif., said the protection schemes built into the draft 802.11g standards cause the slowdown in 802.11g throughput in mixed networks. Zyren sharply disagreed, however, saying the lower data rates in mixed networks results from the need to accommodate 11b clients, which operate at an actual date rate of about 5Mbit/sec.
"The 'b' clients are what slow the network down," not the protection scheme, Zyren said.
Li replied that that's like saying a car has a certain maximum speed impeded by a red light. "If I ignore the red light, I'm going to kill the 'b' guys," Li said.
Leigh Chinitz, chief technology officer in the wireless LAN division of Proxim Corp. in Sunnyvale, Calif., said the slower speeds for 802.11g clients in a mixed network result from the IEEE's desire to ensure interoperability between 11b and 11g hardware.
Proxim has developed a dual-slot access point that contains both 11b and 11g cards, allowing users to maximize data rates with both standards, Chinitz said. The 11b and 11g standards both have three nonoverlapping channels in the 2.4-GHz band, and enterprises can configure a network using a dual-slot access point that allocates one nonoverlapping channel to the 11g standard and another to the 11b standard.
Alan Reiter, an analyst at Wireless Internet & Mobile Computing in Chevy Chase, Md., said the sharp contrast between raw data rates and actual throughput for802.11g illustrates a problem rife throughout the wireless data industry. The industry, as well as cellular carriers, "quote raw, theoretical data rates that are absolutely misleading," said Reiter.
He urged the industry to clearly offer true data rates in packages, product literature and advertisements.

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