Intersil triples 802.11g data rates
Where 802.11b drags 802.11g down
WLAN chipset maker Intersil yesterday revealed technology to improve 802.11g throughput by as much as 300 per cent.
The technology, Nitro, is fully compatible with the latest draft specification for 802.11g, Intersil claimed. Nitro uses prioritisation algorithms and an enhancement of the protection mechanisms built into 802.11g to achieve 3x throughput.
Intersil is aiming the technology at mixed-standard networks, where 802.11b and 802.11g coverage exists side-by-side. In 802.11g-only environments, the performance gain is rather smaller, around 50 per cent, the company said. The more the number of 802.11b nodes outweighs the number of 802.11g nodes, the better the performance hike Nitro can offer 802.11g users.
Nitro works by essentially giving priority to 802.11g packets. The 802.11b standard uses a modulation technique called CCK, while 802.11g uses the same OFDM modulation implemented by 802.11a for data rates over 20Mbps. However, for compatibility with slower 802.11b data rates, 802.11g systems have to cope with CCK traffic too. The 802.11g specification includes rules to protect 802.11g systems from being dragged down by slow CCK packets. If protection isn't implemented, CCK packets interfere with OFDM packets, generating transmission errors that effectively slow 802.11g networks right down.
Nitro implements and extends 802.11g's protection mechanism to limit CCK traffic on the network while a number of OFDM packets are squirted out on the network.
Intersil will offer Nitro with its Prism GT and Prism Duette chipsets. Existing products based on Prism chipsets, including products from the likes of D-Link and Netgear, can be upgraded with Nitro through a firmware patch.
Of course, Nitro will still not bring 802.11g data rates to the raw 54Mbps throughput, but it should increase performance well beyond the 9Mbps (approx.) data rate provided by 802.11b (raw data rate: 11Mbps) - Intersil claims rates of between 20Mbps and 30Mbps.
Nitro is also designed to work "in conjunction with any 802.11g draft compliant solution", but since Intersil claims that most 802.11g implementations over than its own (natch) don't support protection, ie. are not compliant with the draft spec., we wonder how valuable Nitro is where there are few other Prism-based units on the network. ®
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