Getting a Leg Up on 802.11n

Just when you thought you'd mastered the alphabet soup of wireless networking, along comes 802.11n.

There is no agreed-upon industry standard yet but that isnt stopping some companies from rolling out their visions of what an 802.11n product should be.

We tested an early production sample of the Belkin Wireless Pre-N Router, and were impressed with the speed and range benefits 802.11n technology promises. Though not tested here, pre-802.11n and, eventually, actual products based on the standard, when ratified, are and will be backward compatible and interoperable with standards-based 802.11b and 802.11g products. A potential downside: pre-standard products are not guaranteed to work with later 802.11n devices that come out.

/zimages/6/28571.gifClick here to read why the Wi-Fi Alliance is taking a tough stance on "pre-N" products.

The IEEE (Institute of Electrical and Electronics Engineers) 802.11 working group formed Task Group n (TGn) in September 2003 with the mission of developing a standard with a claimed data rate in excess of 200 Mbps, to deliver real-world usable throughput of at least 100 Mbps. By comparison, the theoretical maximum throughput for standards-based 802.11a and 802.11g products is 54 Mbps, and the highest usable throughput we typically see in our wireless testing lab is around 25 Mbps. Thats quite an ambitious leap, and it wasnt until September 2004 that the first batch of proposals was formally introduced.

Not surprisingly, several groups of industry giants have emerged with separate, distinct proposals that are more advantageous to their planned products—each hoping that their proposal will be the one to be adopted. Some components from each camp will likely end up in the final 802.11n standard when it is ratified; ratification is unlikely to happen before late 2005, at the earliest. Unfortunately, with the number of proposals fielded (over 60), ratification could easily stretch into early 2006.

Agere, Atheros, Intel, Nokia, Philips, and Sony form the core of the TGn Sync group which supports the use of 40-Mhz channels—double the spectrum used by standards-based 802.11a/b/g products. Some countries, such as Japan, dont allow the use of 40-Mhz channels, so, hypothetically speaking, any TGn Sync-based products would have to be built to fall back to 20-Mhz channels.

The other industry group emerging goes by the name WWiSE (World-Wide Spectrum Efficiency) Led by Airgo, a pioneer in MIMO (Multiple-Input Multiple-Output) technology, and including other wireless industry chipset manufacturers such as Broadcom, Conexant (which owns the former Intersils WLAN assets), STMicroelectronics, and Texas Instruments, WWiSE has come up with a proposal that sticks with a 20-MHz channel and utilizes 2X2 MIMO (two transmitters and two receivers in each device) and OFDM—the same underlying technology used in the 802.11a and 802.11g standards. Optional components call for either three or four transmit antennas and 40-MHz channels that could drive data rates up to 540 Mpbs.

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