Intersil Adds "Burst Mode" To 802.11g

Intersil has adapted part of the 802.11g draft standard to allow up to three times more throughput in 802.11g networks, the company said Tuesday.

Intersil has adapted part of the 802.11g draft standard to allow up to three times more throughput in 802.11g networks, the company said Tuesday.

The companys Prism "Nitro" technology works with the companys line of Duette and GT components, which have been adopted by companies like Netgear and D-Link. The software is shipping now, although end users will need to contact the OEM for the updated software.

Intersils software works best in crowded networks, where multiple 802.11b and 802.11g access points and cards are competing for bandwidth. Using a technique called "protection" which was built into the 7.1 draft standard of 802.11g, the Nitro technology asks other 802.11b devices to stop transmitting for a brief time, then shoots its own information out into the network in a burst.

"One of the foundations of Intersils design strategy is complete industry standards compliance," said Nick Sargologos, product marketing manager of the wireless networking product group at Intersil. "For a given 802.11x—802.1a, 802,11b, or 802.11g—we are compliant with the proper implementation."

As other vendors have, Intersil is assuming that its compliance with the draft standard of 802.11g will translate into a product which will end up in compliance with the final specification, due to be ratified in June or July. However, the company claims that interoperability wont be an issue.

"Nitro will work with everybody thats g compliant," Sargologos said.

In Intersils tests, the company found that the vast majority of packets being passed wirelessly use the CCK modulation of 802.11b, which passes data at around 11 Mbits/sec. The faster 802.11g specification uses OFDM modulation, also used by 802.11a., but shares the 2.4-GHz band used by 802.11b products. The result? Slower CCK packets clog the wireless airwaves, potentially interfering with 802.11g OFDM packets, even on different channels.

The Nitro technology signals other devices that its preparing to transmit. Using the "protection" technology found within the 802.11g draft specification, the other 802.11b devices stop sending data for a brief window, just milliseconds long. During that "window" the Nitro-equipped Intersil device bursts several packets simultaneously, increasing throughput.

The technology is most effective in crowded environments, where multiple devices are competing for the same wireless bandwidth, Sargologos said. In mixed environments, Intersil estimates the effective throughput will be between 3.6 to 10.6 Mbits/s. In a 802.11g-only environment, the company believes throughput of between 20- and 30-Mbits/s is possible.

However, the Nitro technology is not the same as the "turbo mode" used by other wireless providers, such as Atheros. Atheros 802.11as turbo mode uses multiple channels to stream data in parallel, while the Nitro technology uses a single channel. And although Nitros throughput is high, Intersil recommends that it be used for sending data files, not multimedia, as it lacks the quality-of-service provisions of the upcoming 802.11e standard.

"Nitro" is currently available as a free firmware upgrade, Intersil said.