Trouble for Wifi at 600Mbits

Several companies are expected to release next-generation wireless networking products shortly, based on the first draft of a specification offering rated speeds up to 10 times greater than those of current Wifi products.

The 802.11n draft, approved by an IEEE committee, allows for a maximum theoretical speed of 600Mbits/sec; but, as with all networks, the real throughput is likely to be less than half the rated speed. Even that makes 802.11n faster than most wired networks.

However, analysts warned that the new wave of products based on the draft might be incompatible with those using the final specification, which is not expected to be approved until 2007 at the earliest.

So-called ‘pre-N’ vendors have been jumping the gun on the 11n standard for over two years by using multiple in multiple out (Mimo) technology to increase the rated 54Mbits/sec of 11a and 11g Wifi products by a factor of two or more.

The problem goes back further to the days of dial-up modems, when the technology moved faster than the standards process and many people ended up with ‘pre-standard’ modems that could not connect at full speed with new products.

Pre-N Wifi products offer few problems at the moment as they default to standard 11a or 11g when operating with incompatible wireless networks. Usually this means they work at full speed at home or in the office, and at the slower ‘official’ rate in hotspots.

But within a couple of years, if the world and its hotspots move to the approved 11n standard, pre-N modems could still have to revert to slower speeds while owners of compliant devices are swapping data significantly faster (see story left).

Wifi chipset makers Broadcom, Marvell and Atheros are offering draft-compliant 11n that should appear in products over the coming weeks. Rival Airgo issued a statement saying there was no guarantee these products could be firmware upgradable to conform to the final spec. Analysts Gartner warned companies to avoid ‘pre-N’ products, and labelled claims of draft-compliant chipsets as ‘misleading’ and ‘premature’.

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