Think of the wireless LAN industry as a band of pilgrims en route to Canterbury. But because the path is long and arduous, discord arises, and smaller groups break off to have adventures and make some money along the way.

---

Also: 802.11n update: TGn Sync vs WWiSE

---

Of course, the Promised Land is 802.11n , the IEEE WLAN specification that will provide 100M bit/sec-plus data throughput rates. But because ratification of the spec isn't expected until late 2006, vendors have begun offering products with enhanced speed, range and coverage using a mix of proprietary technologies.

In December, Belkin began offering what it's calling "pre-N" routers and adapters. Linksys, Netgear and D-Link have since announced multiple-input/multiple-output (MIMO )-based products; and Buffalo Technology, SMC Networks and Actiontec have similar plans in motion.

In one sense, this is good news for small offices and consumers whose current wireless networks fall short, and for early adopters experimenting with network media adapters and Media PCs to stream content between TVs, stereos and PCs. The products all tout double (or more) the throughput and range of today's standards-based 802.11g and 802.11a products, which makes them suitable (at least in theory) to carry multiple streams of high-definition television.

But in another, the rejection of standards turns the WLAN industry on its head, which for several years has enjoyed enormous growth partly because of its adherence to standards and insistence on interoperability.

The new MIMO market breaks down into three camps: Belkin and Linksys offer MIMO gear based on Airgo's chipset; Netgear has partnered with smart antenna vendor Video54 and plans to ship gear this spring; D-Link (and soon SMC) is using Atheros' new Super G with MIMO chipset in products available now.

In a general sense, MIMO uses multiple antennas and radios in the same frequency to transmit data, and is the basis for the 802.11n spec.

Airgo's CEO Greg Raleigh, who wrote the first academic paper on MIMO in 1996 at Stamford and has 26 patents in the field, says "True MIMO" (a term Airgo has patented) requires not only multiple antennas and radios on both the transmit and receive sides of the link but also the ability to do spatial multiplexing. Spacial multiplexing allows for the transmission of multiple distinct datastreams over multiple radios in the same band at the same time, effectively doubling (or tripling) data throughput. Think of it as sipping milk through two (or more) straws at once.

Specifically, Airgo's MIMO chipset transmits two distinct datastreams simultaneously at 54M bit/sec to yield 108M bit/sec. Linksys, which uses the Airgo chip in its new Wireless-G Broadband Router with SRX, says it gets about 40M bit/sec actual throughput.

However, Atheros, and Netgear with Video54, are pushing to broaden the definition of MIMO to not require spacial multiplexing. Atheros CEO Craig Barratt says, "Our position is that MIMO is any system that has multiple antennas at both ends of the link being used concurrently. How you actually use them is subject to various choices in implementation."