Atheros updates Wi-Fi speed booster tech

Will no longer degrade nearby WLANs

By Tony Smith, 17th March 2004

Regcast training : Hyper-V 3.0, VM high availability and disaster recovery

Wi-Fi chip maker Atheros this week has updated its 'standards plus' WLAN speed-boosting technology, Super G, to make devices based on its 802.11g chipsets better network neighbours.

Super G extends 802.11g's maximum throughput of 54Mbps to 108Mbps. Data compression and burst transmission together form one part of the story, the other is the 'bonding' multiple channels into a single, fatter data pipe.

It's this second element, called Turbo mode, that has caused all the fuss. Last November, rival Wi-Fi chip maker Broadcom alleged that Turbo operation slowed down any nearby wireless network that was sticking to the IEEE Wi-Fi standard.

Super G's Turbo mode simultaneously runs data across channels five and six of the 11 22MHz-wide segments into which the Wi-Fi standard subdivides the 2.4GHz band. Because all but three channels overlap there is inevitably some interference with adjacent channels, but this is an issue with almost all Wi-Fi products, and one of the many reasons users never see full speed.

Not so, alleges Broadcom. It claimed Turbo cross-channel interference stretches further than the IEEE standard 'allows', causing problems with networks that have flipped to channel one or 11. As a result, Wi-Fi networks utilising these bands slow down by dropping their data rate in order to reduce the number of errors induced by the interference.

Independent tests confirmed Broadcom's claims. "A Super G wireless LAN running at full speed will interfere with an 11g WLAN also running at full speed. Severe throughput loss in the 11g WLAN can occur up to 30 feet away and significant throughput loss may still be seen around 50 feet," wrote Tim Higgins of web site Small Net Builder.

The upgrade, released this week and dubbed Dynamic Turbo, forces Atheros-based devices to check for traffic in the channels they hope to combine. If the channels are clear, the chipset bonds them. It continually checks for other traffic, and turns off bonding if another network using the bonded channels is detected.

Atheros spins the update not as a fix to the interference problem, but as an innovation that plays to the US Federal Communications Commission's cognitive radio initiative - 'smart' wireless devices that choose the least used part of the available spectrum to operate in.

Indeed, the companies denies that any of its hardware manufacturer customers have received complaints from end users that they have suffered problems with the technology. Not that they would, of course - it's other folks' networks that suffer.

Not that they will now, thanks to the upgrade. Atheros has shipped the software to its customers, who may now update their devices' firmware. D-Link, for one, has already posted the update as a free download on its website. ®