Broadcom blames Atheros for bad WLAN performance
Not our fault, Wi-Fi chip maker responds
Broadcom last week fired a broadside against Wi-Fi chipset maker Atheros, alleging the latter's proprietary performance and range-boosting Super G technology slows down nearby standards-based wireless networks.
According to Broadcom, Super G, which doubles 802.11g's 54Mbps raw data rate (but only if you have two products containing Atheros chipsets at either end of the link), interferes with nearby networks, sometimes dragging data rates down to 1Mbps - even when they operate on a different channel.
Broadcom said it would detail its research this week, to allow independent verification of its findings. Atheros reckons no one will be able to do so. It denies the claim, saying its system causes no more network degradation than any other Wi-Fi product.
D-Link, which makes WLAN kit based on Atheros technology follows the chipmaker's line, PC World reports.
At issue is Super G's Turbo mode, which simultaneously runs data across channels five and six of the 11 22MHz-wide segments into which the Wi-Fi specification 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. By choosing channels five and six, says Atheros, it has ensured that channels one and 11 remain clear.
Not so, alleges Broadcom. It says 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.
This sort of thing has happened before, particularly with Bluetooth and Wi-Fi getting in each other's way, though Bluetooth's ability to hop around the 79 1MHz channels it splits the 2.4GHz band into generally ensures that interference is kept to a minimum.
That hasn't stopped Broadcom, for one, touting proprietary co-existence technology. Today it unveiled InConcert, which allows Bluetooth and Wi-Fi to "intelligently share" the 2.4GHz band - but again, only if you have Broadcom Bluetooth and Wi-Fi chips in all the relevant clients and access points. Essentially, InConcert forces both radios to synchronise their transmissions to avoid interference. ®
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