Atheros and Broadcom Both Guilty of Wireless Problems

A year ago, I thought 802.11g was a dumb idea, but Ive changed my tune. With a ratified standard, and 802.11b interoperability, Ive become a big fan of the 54Mbps wireless networking scheme. Even Cisco and Microsoft have released 802.11g products, so you know its here for good.

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But this week brought allegations by 802.11 chip maker Broadcom that chips made by rival Atheros can be so noisy—in a proprietary 108Mbit mode—that they block other 2.4GHz wireless devices, including phones, Bluetooth mice and keyboards, and other Wi-Fi devices.

But Broadcoms not innocent here. The two feuding chip makers—and the third big wireless chipmaker, Intersil—are all guilty of putting marketecture ahead of customers. And thats bad news for everyone.

Lets start with Broadcoms allegations, which they laid out in a private meeting room at this years Comdex. The Atheros 802.11g chipset—used primarily by D-Link and NetGear—include the ability to ratchet up the 54Mbps speeds to (they claim) 108Mbps. This "Turbo" mode (called Super G by D-Link) only works when both the access point and the mobile device are running Atheros-based wireless network cards, and when both are set to run at "Super G" mode using configuration software.

Super G gets a significant portion of its performance gain by channel bonding—multiplexing wireless traffic over two channels, instead of one. That doesnt sound like a big deal, because there are 11 selectable channels for 802.11g Wi-Fi, but that number is deceiving. In fact, there are only three non-overlapping channels, 1, 6 and 11.

There wouldnt be much of a problem if the channel bonding simply took over channels 1 and 6, and left 11 alone. But the Atheros implementation centers the two channels in the middle of channel 6, which means part of channel one, and part of channel 11 are used up by the channel bonding scheme.

Next page: An in-depth look at Broadcoms test setup and results.