x

Don't Go to War Over .11n

With an expected usable throughput of at least 100 Mbit/s per device, the upcoming 802.11n standard is set to storm the wireless LAN scene – and anyone who thinks different is clearly either smokin', drinkin', or snoozin'.

In the enterprise, 802.11n will help make IT guys more comfortable with the idea that wireless is, after all, a sensible replacement for cable. And in the home, it will bring you one step closer to that wireless TV/DVD/TiVO/iPOD combo you've always dreamt of.

The only problem is that the vendors that are supposed to be drafting the spec are about to fall into the classic standards-group trap: Half of 'em want to do it one way, and half of 'em want to do it another way.

Although the first proposals aren't due to be submitted to the Institute of Electrical and Electronics Engineers Inc. (IEEE) until mid August, two major factions have already emerged. The first, and so far the most public, is nSynch (no, not that nSync). The second, and thus far a mite more secretive, is WWiSE.

The table below summarizes some of the differences – as we understand them today – between the two groups.

Table 1: Comparison of Possible Proposals to 802.11 TGn
nSynch WWiSE Not Declared
Chipset Members Atheros, Agere, Philips, Intel Airgo, Broadcom, Conexant, STMicro, Texas Instruments, IceFyre, Realtek, Engim, Marvell, Atmel, others
Combined Chipset Market Share* 30 percent to 50 percent 50 percent to 70 percent 5 percent
System Members Nortel, Cisco, Sony, Toshiba, Nokia, Matsushita, Samsung Mitsubishi, Motorola Not applicable
IP Licensing RAND RAND-Z Not applicable
Channel Width 10 MHz, 20 MHz, and 40 MHz mandatory 20 MHz mandatory, 40 MHz optional 20 MHz
No. of Channels in 5GHz Band 14 24 Not applicable
MIMO Two antennas mandatory, four antennas optional Four antennas mandatory Various
Raw Data Rate 250 Mbit/s (2x125 Mbit/s), expandable to 500 Mbit/s Unconfirmed info indicates 216 Mbit/s (4x56 Mbit/s) Various
Frequencies 5 GHz mandatory, 2.4 GHz optional 5 GHz mandatory, no info available on 2.4 GHz Not applicable
Source: Unstrung Insider




The technical differences between the two proposals can essentially be summarized as "2x40" versus "4x20." Here's how it works:

nSynch's idea is to develop a device that uses two MIMO (multiple input, multiple output) antennas, in combination with 40MHz channels, to create a device that will provide 250 Mbit/s of raw bandwidth and 175 Mbit/s of usable throughput.

Members of the WWiSE coalition, meanwhile, claim that this plan is flawed. Not only will it reduce the number of available non-overlapping 802.11 channels and be illegal in Japan, they say, but it is also overkill for the job at hand.

Instead, WWiSE will propose a device that uses four MIMO antennas, while sticking with the 20MHz channels currently specified by 802.11 – which will produce, we think, raw bandwidth of around 216 Mbit/s and usable throughput of 162 Mbit/s. This approach, say supporters, is more sophisticated, more spectrally efficient, and will face fewer regulatory obstacles.

nSynch boosters counter with the claim that using four antennas would be unnecessarily complex, more expensive, and inappropriate for mobile devices. And so the argument continues, in a (neverending?) cycle of claim and counterclaim.

One way to resolve the standoff would be for each group to accept optional extensions to the standard that would allow 2x40, 4x40, and 4x20 products.

"I think it makes sense to have a flexible solution to the number of antennas," says Eduado Merli, wireless LAN business manager at STMicroelectronics NV (NYSE: STM), a member of WWiSE. "For some devices, it could make sense to have a lower number of antennas."

And on the channel-width issue, James Zyren, marketing director at Conexant Systems Inc. (Nasdaq: CNXT), says WWiSE will also offer optional extensions. "20MHz channels strike us as the right way to go," he says, "40MHz should be optional."

But too many options make for a messy solution, says Sheung Li, product line manager at Atheros Communications Inc. (Nasdaq: ATHR), a member of nSynch. "The terms 'mandatory' and 'optional' are a red herring," says Li. "The fact is, with this many people supporting it, 40MHz is going to get there.

For those of you good at math, you'll see that if "2x40" and "4x20" were equations, they'd both add up to the same thing. And so it is with 802.11n: Ultimately, both groups are aiming for the same outcome. What's required, then, is compromise.

— Gabriel Brown, Chief Analyst, Unstrung Insider


Chipset vendors' product strategies for the upcoming high-throughput 802.11n standard are analyzed in Wireless LAN Chipsets: MIMO and the Road to 802.11n, which is available as part of an annual subscription (12 monthly issues) to Unstrung Insider, priced at $1,350. Individual reports are available for $900.

Be the first to post a comment regarding this story.
HOME
Sign In
SEARCH
CLOSE
MORE
CLOSE